File: | lib/Analysis/ScalarEvolution.cpp |
Warning: | line 8112, column 23 Value stored to 'MultipleInitValues' is never read |
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1 | //===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===// |
2 | // |
3 | // The LLVM Compiler Infrastructure |
4 | // |
5 | // This file is distributed under the University of Illinois Open Source |
6 | // License. See LICENSE.TXT for details. |
7 | // |
8 | //===----------------------------------------------------------------------===// |
9 | // |
10 | // This file contains the implementation of the scalar evolution analysis |
11 | // engine, which is used primarily to analyze expressions involving induction |
12 | // variables in loops. |
13 | // |
14 | // There are several aspects to this library. First is the representation of |
15 | // scalar expressions, which are represented as subclasses of the SCEV class. |
16 | // These classes are used to represent certain types of subexpressions that we |
17 | // can handle. We only create one SCEV of a particular shape, so |
18 | // pointer-comparisons for equality are legal. |
19 | // |
20 | // One important aspect of the SCEV objects is that they are never cyclic, even |
21 | // if there is a cycle in the dataflow for an expression (ie, a PHI node). If |
22 | // the PHI node is one of the idioms that we can represent (e.g., a polynomial |
23 | // recurrence) then we represent it directly as a recurrence node, otherwise we |
24 | // represent it as a SCEVUnknown node. |
25 | // |
26 | // In addition to being able to represent expressions of various types, we also |
27 | // have folders that are used to build the *canonical* representation for a |
28 | // particular expression. These folders are capable of using a variety of |
29 | // rewrite rules to simplify the expressions. |
30 | // |
31 | // Once the folders are defined, we can implement the more interesting |
32 | // higher-level code, such as the code that recognizes PHI nodes of various |
33 | // types, computes the execution count of a loop, etc. |
34 | // |
35 | // TODO: We should use these routines and value representations to implement |
36 | // dependence analysis! |
37 | // |
38 | //===----------------------------------------------------------------------===// |
39 | // |
40 | // There are several good references for the techniques used in this analysis. |
41 | // |
42 | // Chains of recurrences -- a method to expedite the evaluation |
43 | // of closed-form functions |
44 | // Olaf Bachmann, Paul S. Wang, Eugene V. Zima |
45 | // |
46 | // On computational properties of chains of recurrences |
47 | // Eugene V. Zima |
48 | // |
49 | // Symbolic Evaluation of Chains of Recurrences for Loop Optimization |
50 | // Robert A. van Engelen |
51 | // |
52 | // Efficient Symbolic Analysis for Optimizing Compilers |
53 | // Robert A. van Engelen |
54 | // |
55 | // Using the chains of recurrences algebra for data dependence testing and |
56 | // induction variable substitution |
57 | // MS Thesis, Johnie Birch |
58 | // |
59 | //===----------------------------------------------------------------------===// |
60 | |
61 | #include "llvm/Analysis/ScalarEvolution.h" |
62 | #include "llvm/ADT/APInt.h" |
63 | #include "llvm/ADT/ArrayRef.h" |
64 | #include "llvm/ADT/DenseMap.h" |
65 | #include "llvm/ADT/DepthFirstIterator.h" |
66 | #include "llvm/ADT/EquivalenceClasses.h" |
67 | #include "llvm/ADT/FoldingSet.h" |
68 | #include "llvm/ADT/None.h" |
69 | #include "llvm/ADT/Optional.h" |
70 | #include "llvm/ADT/STLExtras.h" |
71 | #include "llvm/ADT/ScopeExit.h" |
72 | #include "llvm/ADT/Sequence.h" |
73 | #include "llvm/ADT/SetVector.h" |
74 | #include "llvm/ADT/SmallPtrSet.h" |
75 | #include "llvm/ADT/SmallSet.h" |
76 | #include "llvm/ADT/SmallVector.h" |
77 | #include "llvm/ADT/Statistic.h" |
78 | #include "llvm/ADT/StringRef.h" |
79 | #include "llvm/Analysis/AssumptionCache.h" |
80 | #include "llvm/Analysis/ConstantFolding.h" |
81 | #include "llvm/Analysis/InstructionSimplify.h" |
82 | #include "llvm/Analysis/LoopInfo.h" |
83 | #include "llvm/Analysis/ScalarEvolutionExpressions.h" |
84 | #include "llvm/Analysis/TargetLibraryInfo.h" |
85 | #include "llvm/Analysis/ValueTracking.h" |
86 | #include "llvm/Config/llvm-config.h" |
87 | #include "llvm/IR/Argument.h" |
88 | #include "llvm/IR/BasicBlock.h" |
89 | #include "llvm/IR/CFG.h" |
90 | #include "llvm/IR/CallSite.h" |
91 | #include "llvm/IR/Constant.h" |
92 | #include "llvm/IR/ConstantRange.h" |
93 | #include "llvm/IR/Constants.h" |
94 | #include "llvm/IR/DataLayout.h" |
95 | #include "llvm/IR/DerivedTypes.h" |
96 | #include "llvm/IR/Dominators.h" |
97 | #include "llvm/IR/Function.h" |
98 | #include "llvm/IR/GlobalAlias.h" |
99 | #include "llvm/IR/GlobalValue.h" |
100 | #include "llvm/IR/GlobalVariable.h" |
101 | #include "llvm/IR/InstIterator.h" |
102 | #include "llvm/IR/InstrTypes.h" |
103 | #include "llvm/IR/Instruction.h" |
104 | #include "llvm/IR/Instructions.h" |
105 | #include "llvm/IR/IntrinsicInst.h" |
106 | #include "llvm/IR/Intrinsics.h" |
107 | #include "llvm/IR/LLVMContext.h" |
108 | #include "llvm/IR/Metadata.h" |
109 | #include "llvm/IR/Operator.h" |
110 | #include "llvm/IR/PatternMatch.h" |
111 | #include "llvm/IR/Type.h" |
112 | #include "llvm/IR/Use.h" |
113 | #include "llvm/IR/User.h" |
114 | #include "llvm/IR/Value.h" |
115 | #include "llvm/IR/Verifier.h" |
116 | #include "llvm/Pass.h" |
117 | #include "llvm/Support/Casting.h" |
118 | #include "llvm/Support/CommandLine.h" |
119 | #include "llvm/Support/Compiler.h" |
120 | #include "llvm/Support/Debug.h" |
121 | #include "llvm/Support/ErrorHandling.h" |
122 | #include "llvm/Support/KnownBits.h" |
123 | #include "llvm/Support/SaveAndRestore.h" |
124 | #include "llvm/Support/raw_ostream.h" |
125 | #include <algorithm> |
126 | #include <cassert> |
127 | #include <climits> |
128 | #include <cstddef> |
129 | #include <cstdint> |
130 | #include <cstdlib> |
131 | #include <map> |
132 | #include <memory> |
133 | #include <tuple> |
134 | #include <utility> |
135 | #include <vector> |
136 | |
137 | using namespace llvm; |
138 | |
139 | #define DEBUG_TYPE"scalar-evolution" "scalar-evolution" |
140 | |
141 | STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution" , "NumArrayLenItCounts", "Number of trip counts computed with array length" , {0}, {false}} |
142 | "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution" , "NumArrayLenItCounts", "Number of trip counts computed with array length" , {0}, {false}}; |
143 | STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution" , "NumTripCountsComputed", "Number of loops with predictable loop counts" , {0}, {false}} |
144 | "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution" , "NumTripCountsComputed", "Number of loops with predictable loop counts" , {0}, {false}}; |
145 | STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution" , "NumTripCountsNotComputed", "Number of loops without predictable loop counts" , {0}, {false}} |
146 | "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution" , "NumTripCountsNotComputed", "Number of loops without predictable loop counts" , {0}, {false}}; |
147 | STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution" , "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force" , {0}, {false}} |
148 | "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution" , "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force" , {0}, {false}}; |
149 | |
150 | static cl::opt<unsigned> |
151 | MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden, |
152 | cl::desc("Maximum number of iterations SCEV will " |
153 | "symbolically execute a constant " |
154 | "derived loop"), |
155 | cl::init(100)); |
156 | |
157 | // FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean. |
158 | static cl::opt<bool> VerifySCEV( |
159 | "verify-scev", cl::Hidden, |
160 | cl::desc("Verify ScalarEvolution's backedge taken counts (slow)")); |
161 | static cl::opt<bool> |
162 | VerifySCEVMap("verify-scev-maps", cl::Hidden, |
163 | cl::desc("Verify no dangling value in ScalarEvolution's " |
164 | "ExprValueMap (slow)")); |
165 | |
166 | static cl::opt<bool> VerifyIR( |
167 | "scev-verify-ir", cl::Hidden, |
168 | cl::desc("Verify IR correctness when making sensitive SCEV queries (slow)"), |
169 | cl::init(false)); |
170 | |
171 | static cl::opt<unsigned> MulOpsInlineThreshold( |
172 | "scev-mulops-inline-threshold", cl::Hidden, |
173 | cl::desc("Threshold for inlining multiplication operands into a SCEV"), |
174 | cl::init(32)); |
175 | |
176 | static cl::opt<unsigned> AddOpsInlineThreshold( |
177 | "scev-addops-inline-threshold", cl::Hidden, |
178 | cl::desc("Threshold for inlining addition operands into a SCEV"), |
179 | cl::init(500)); |
180 | |
181 | static cl::opt<unsigned> MaxSCEVCompareDepth( |
182 | "scalar-evolution-max-scev-compare-depth", cl::Hidden, |
183 | cl::desc("Maximum depth of recursive SCEV complexity comparisons"), |
184 | cl::init(32)); |
185 | |
186 | static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth( |
187 | "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden, |
188 | cl::desc("Maximum depth of recursive SCEV operations implication analysis"), |
189 | cl::init(2)); |
190 | |
191 | static cl::opt<unsigned> MaxValueCompareDepth( |
192 | "scalar-evolution-max-value-compare-depth", cl::Hidden, |
193 | cl::desc("Maximum depth of recursive value complexity comparisons"), |
194 | cl::init(2)); |
195 | |
196 | static cl::opt<unsigned> |
197 | MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden, |
198 | cl::desc("Maximum depth of recursive arithmetics"), |
199 | cl::init(32)); |
200 | |
201 | static cl::opt<unsigned> MaxConstantEvolvingDepth( |
202 | "scalar-evolution-max-constant-evolving-depth", cl::Hidden, |
203 | cl::desc("Maximum depth of recursive constant evolving"), cl::init(32)); |
204 | |
205 | static cl::opt<unsigned> |
206 | MaxExtDepth("scalar-evolution-max-ext-depth", cl::Hidden, |
207 | cl::desc("Maximum depth of recursive SExt/ZExt"), |
208 | cl::init(8)); |
209 | |
210 | static cl::opt<unsigned> |
211 | MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden, |
212 | cl::desc("Max coefficients in AddRec during evolving"), |
213 | cl::init(8)); |
214 | |
215 | //===----------------------------------------------------------------------===// |
216 | // SCEV class definitions |
217 | //===----------------------------------------------------------------------===// |
218 | |
219 | //===----------------------------------------------------------------------===// |
220 | // Implementation of the SCEV class. |
221 | // |
222 | |
223 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
224 | LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const { |
225 | print(dbgs()); |
226 | dbgs() << '\n'; |
227 | } |
228 | #endif |
229 | |
230 | void SCEV::print(raw_ostream &OS) const { |
231 | switch (static_cast<SCEVTypes>(getSCEVType())) { |
232 | case scConstant: |
233 | cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false); |
234 | return; |
235 | case scTruncate: { |
236 | const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this); |
237 | const SCEV *Op = Trunc->getOperand(); |
238 | OS << "(trunc " << *Op->getType() << " " << *Op << " to " |
239 | << *Trunc->getType() << ")"; |
240 | return; |
241 | } |
242 | case scZeroExtend: { |
243 | const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this); |
244 | const SCEV *Op = ZExt->getOperand(); |
245 | OS << "(zext " << *Op->getType() << " " << *Op << " to " |
246 | << *ZExt->getType() << ")"; |
247 | return; |
248 | } |
249 | case scSignExtend: { |
250 | const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this); |
251 | const SCEV *Op = SExt->getOperand(); |
252 | OS << "(sext " << *Op->getType() << " " << *Op << " to " |
253 | << *SExt->getType() << ")"; |
254 | return; |
255 | } |
256 | case scAddRecExpr: { |
257 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this); |
258 | OS << "{" << *AR->getOperand(0); |
259 | for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i) |
260 | OS << ",+," << *AR->getOperand(i); |
261 | OS << "}<"; |
262 | if (AR->hasNoUnsignedWrap()) |
263 | OS << "nuw><"; |
264 | if (AR->hasNoSignedWrap()) |
265 | OS << "nsw><"; |
266 | if (AR->hasNoSelfWrap() && |
267 | !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW))) |
268 | OS << "nw><"; |
269 | AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
270 | OS << ">"; |
271 | return; |
272 | } |
273 | case scAddExpr: |
274 | case scMulExpr: |
275 | case scUMaxExpr: |
276 | case scSMaxExpr: { |
277 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this); |
278 | const char *OpStr = nullptr; |
279 | switch (NAry->getSCEVType()) { |
280 | case scAddExpr: OpStr = " + "; break; |
281 | case scMulExpr: OpStr = " * "; break; |
282 | case scUMaxExpr: OpStr = " umax "; break; |
283 | case scSMaxExpr: OpStr = " smax "; break; |
284 | } |
285 | OS << "("; |
286 | for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end(); |
287 | I != E; ++I) { |
288 | OS << **I; |
289 | if (std::next(I) != E) |
290 | OS << OpStr; |
291 | } |
292 | OS << ")"; |
293 | switch (NAry->getSCEVType()) { |
294 | case scAddExpr: |
295 | case scMulExpr: |
296 | if (NAry->hasNoUnsignedWrap()) |
297 | OS << "<nuw>"; |
298 | if (NAry->hasNoSignedWrap()) |
299 | OS << "<nsw>"; |
300 | } |
301 | return; |
302 | } |
303 | case scUDivExpr: { |
304 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this); |
305 | OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")"; |
306 | return; |
307 | } |
308 | case scUnknown: { |
309 | const SCEVUnknown *U = cast<SCEVUnknown>(this); |
310 | Type *AllocTy; |
311 | if (U->isSizeOf(AllocTy)) { |
312 | OS << "sizeof(" << *AllocTy << ")"; |
313 | return; |
314 | } |
315 | if (U->isAlignOf(AllocTy)) { |
316 | OS << "alignof(" << *AllocTy << ")"; |
317 | return; |
318 | } |
319 | |
320 | Type *CTy; |
321 | Constant *FieldNo; |
322 | if (U->isOffsetOf(CTy, FieldNo)) { |
323 | OS << "offsetof(" << *CTy << ", "; |
324 | FieldNo->printAsOperand(OS, false); |
325 | OS << ")"; |
326 | return; |
327 | } |
328 | |
329 | // Otherwise just print it normally. |
330 | U->getValue()->printAsOperand(OS, false); |
331 | return; |
332 | } |
333 | case scCouldNotCompute: |
334 | OS << "***COULDNOTCOMPUTE***"; |
335 | return; |
336 | } |
337 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 337); |
338 | } |
339 | |
340 | Type *SCEV::getType() const { |
341 | switch (static_cast<SCEVTypes>(getSCEVType())) { |
342 | case scConstant: |
343 | return cast<SCEVConstant>(this)->getType(); |
344 | case scTruncate: |
345 | case scZeroExtend: |
346 | case scSignExtend: |
347 | return cast<SCEVCastExpr>(this)->getType(); |
348 | case scAddRecExpr: |
349 | case scMulExpr: |
350 | case scUMaxExpr: |
351 | case scSMaxExpr: |
352 | return cast<SCEVNAryExpr>(this)->getType(); |
353 | case scAddExpr: |
354 | return cast<SCEVAddExpr>(this)->getType(); |
355 | case scUDivExpr: |
356 | return cast<SCEVUDivExpr>(this)->getType(); |
357 | case scUnknown: |
358 | return cast<SCEVUnknown>(this)->getType(); |
359 | case scCouldNotCompute: |
360 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 360); |
361 | } |
362 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 362); |
363 | } |
364 | |
365 | bool SCEV::isZero() const { |
366 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
367 | return SC->getValue()->isZero(); |
368 | return false; |
369 | } |
370 | |
371 | bool SCEV::isOne() const { |
372 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
373 | return SC->getValue()->isOne(); |
374 | return false; |
375 | } |
376 | |
377 | bool SCEV::isAllOnesValue() const { |
378 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this)) |
379 | return SC->getValue()->isMinusOne(); |
380 | return false; |
381 | } |
382 | |
383 | bool SCEV::isNonConstantNegative() const { |
384 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this); |
385 | if (!Mul) return false; |
386 | |
387 | // If there is a constant factor, it will be first. |
388 | const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0)); |
389 | if (!SC) return false; |
390 | |
391 | // Return true if the value is negative, this matches things like (-42 * V). |
392 | return SC->getAPInt().isNegative(); |
393 | } |
394 | |
395 | SCEVCouldNotCompute::SCEVCouldNotCompute() : |
396 | SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {} |
397 | |
398 | bool SCEVCouldNotCompute::classof(const SCEV *S) { |
399 | return S->getSCEVType() == scCouldNotCompute; |
400 | } |
401 | |
402 | const SCEV *ScalarEvolution::getConstant(ConstantInt *V) { |
403 | FoldingSetNodeID ID; |
404 | ID.AddInteger(scConstant); |
405 | ID.AddPointer(V); |
406 | void *IP = nullptr; |
407 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
408 | SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V); |
409 | UniqueSCEVs.InsertNode(S, IP); |
410 | return S; |
411 | } |
412 | |
413 | const SCEV *ScalarEvolution::getConstant(const APInt &Val) { |
414 | return getConstant(ConstantInt::get(getContext(), Val)); |
415 | } |
416 | |
417 | const SCEV * |
418 | ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) { |
419 | IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty)); |
420 | return getConstant(ConstantInt::get(ITy, V, isSigned)); |
421 | } |
422 | |
423 | SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID, |
424 | unsigned SCEVTy, const SCEV *op, Type *ty) |
425 | : SCEV(ID, SCEVTy), Op(op), Ty(ty) {} |
426 | |
427 | SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID, |
428 | const SCEV *op, Type *ty) |
429 | : SCEVCastExpr(ID, scTruncate, op, ty) { |
430 | assert(Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy () && "Cannot truncate non-integer value!") ? static_cast <void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 431, __PRETTY_FUNCTION__)) |
431 | "Cannot truncate non-integer value!")((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy () && "Cannot truncate non-integer value!") ? static_cast <void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate non-integer value!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 431, __PRETTY_FUNCTION__)); |
432 | } |
433 | |
434 | SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID, |
435 | const SCEV *op, Type *ty) |
436 | : SCEVCastExpr(ID, scZeroExtend, op, ty) { |
437 | assert(Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy () && "Cannot zero extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 438, __PRETTY_FUNCTION__)) |
438 | "Cannot zero extend non-integer value!")((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy () && "Cannot zero extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot zero extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 438, __PRETTY_FUNCTION__)); |
439 | } |
440 | |
441 | SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID, |
442 | const SCEV *op, Type *ty) |
443 | : SCEVCastExpr(ID, scSignExtend, op, ty) { |
444 | assert(Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy () && "Cannot sign extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 445, __PRETTY_FUNCTION__)) |
445 | "Cannot sign extend non-integer value!")((Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy () && "Cannot sign extend non-integer value!") ? static_cast <void> (0) : __assert_fail ("Op->getType()->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot sign extend non-integer value!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 445, __PRETTY_FUNCTION__)); |
446 | } |
447 | |
448 | void SCEVUnknown::deleted() { |
449 | // Clear this SCEVUnknown from various maps. |
450 | SE->forgetMemoizedResults(this); |
451 | |
452 | // Remove this SCEVUnknown from the uniquing map. |
453 | SE->UniqueSCEVs.RemoveNode(this); |
454 | |
455 | // Release the value. |
456 | setValPtr(nullptr); |
457 | } |
458 | |
459 | void SCEVUnknown::allUsesReplacedWith(Value *New) { |
460 | // Remove this SCEVUnknown from the uniquing map. |
461 | SE->UniqueSCEVs.RemoveNode(this); |
462 | |
463 | // Update this SCEVUnknown to point to the new value. This is needed |
464 | // because there may still be outstanding SCEVs which still point to |
465 | // this SCEVUnknown. |
466 | setValPtr(New); |
467 | } |
468 | |
469 | bool SCEVUnknown::isSizeOf(Type *&AllocTy) const { |
470 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
471 | if (VCE->getOpcode() == Instruction::PtrToInt) |
472 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
473 | if (CE->getOpcode() == Instruction::GetElementPtr && |
474 | CE->getOperand(0)->isNullValue() && |
475 | CE->getNumOperands() == 2) |
476 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1))) |
477 | if (CI->isOne()) { |
478 | AllocTy = cast<PointerType>(CE->getOperand(0)->getType()) |
479 | ->getElementType(); |
480 | return true; |
481 | } |
482 | |
483 | return false; |
484 | } |
485 | |
486 | bool SCEVUnknown::isAlignOf(Type *&AllocTy) const { |
487 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
488 | if (VCE->getOpcode() == Instruction::PtrToInt) |
489 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
490 | if (CE->getOpcode() == Instruction::GetElementPtr && |
491 | CE->getOperand(0)->isNullValue()) { |
492 | Type *Ty = |
493 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
494 | if (StructType *STy = dyn_cast<StructType>(Ty)) |
495 | if (!STy->isPacked() && |
496 | CE->getNumOperands() == 3 && |
497 | CE->getOperand(1)->isNullValue()) { |
498 | if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2))) |
499 | if (CI->isOne() && |
500 | STy->getNumElements() == 2 && |
501 | STy->getElementType(0)->isIntegerTy(1)) { |
502 | AllocTy = STy->getElementType(1); |
503 | return true; |
504 | } |
505 | } |
506 | } |
507 | |
508 | return false; |
509 | } |
510 | |
511 | bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const { |
512 | if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue())) |
513 | if (VCE->getOpcode() == Instruction::PtrToInt) |
514 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0))) |
515 | if (CE->getOpcode() == Instruction::GetElementPtr && |
516 | CE->getNumOperands() == 3 && |
517 | CE->getOperand(0)->isNullValue() && |
518 | CE->getOperand(1)->isNullValue()) { |
519 | Type *Ty = |
520 | cast<PointerType>(CE->getOperand(0)->getType())->getElementType(); |
521 | // Ignore vector types here so that ScalarEvolutionExpander doesn't |
522 | // emit getelementptrs that index into vectors. |
523 | if (Ty->isStructTy() || Ty->isArrayTy()) { |
524 | CTy = Ty; |
525 | FieldNo = CE->getOperand(2); |
526 | return true; |
527 | } |
528 | } |
529 | |
530 | return false; |
531 | } |
532 | |
533 | //===----------------------------------------------------------------------===// |
534 | // SCEV Utilities |
535 | //===----------------------------------------------------------------------===// |
536 | |
537 | /// Compare the two values \p LV and \p RV in terms of their "complexity" where |
538 | /// "complexity" is a partial (and somewhat ad-hoc) relation used to order |
539 | /// operands in SCEV expressions. \p EqCache is a set of pairs of values that |
540 | /// have been previously deemed to be "equally complex" by this routine. It is |
541 | /// intended to avoid exponential time complexity in cases like: |
542 | /// |
543 | /// %a = f(%x, %y) |
544 | /// %b = f(%a, %a) |
545 | /// %c = f(%b, %b) |
546 | /// |
547 | /// %d = f(%x, %y) |
548 | /// %e = f(%d, %d) |
549 | /// %f = f(%e, %e) |
550 | /// |
551 | /// CompareValueComplexity(%f, %c) |
552 | /// |
553 | /// Since we do not continue running this routine on expression trees once we |
554 | /// have seen unequal values, there is no need to track them in the cache. |
555 | static int |
556 | CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue, |
557 | const LoopInfo *const LI, Value *LV, Value *RV, |
558 | unsigned Depth) { |
559 | if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV)) |
560 | return 0; |
561 | |
562 | // Order pointer values after integer values. This helps SCEVExpander form |
563 | // GEPs. |
564 | bool LIsPointer = LV->getType()->isPointerTy(), |
565 | RIsPointer = RV->getType()->isPointerTy(); |
566 | if (LIsPointer != RIsPointer) |
567 | return (int)LIsPointer - (int)RIsPointer; |
568 | |
569 | // Compare getValueID values. |
570 | unsigned LID = LV->getValueID(), RID = RV->getValueID(); |
571 | if (LID != RID) |
572 | return (int)LID - (int)RID; |
573 | |
574 | // Sort arguments by their position. |
575 | if (const auto *LA = dyn_cast<Argument>(LV)) { |
576 | const auto *RA = cast<Argument>(RV); |
577 | unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo(); |
578 | return (int)LArgNo - (int)RArgNo; |
579 | } |
580 | |
581 | if (const auto *LGV = dyn_cast<GlobalValue>(LV)) { |
582 | const auto *RGV = cast<GlobalValue>(RV); |
583 | |
584 | const auto IsGVNameSemantic = [&](const GlobalValue *GV) { |
585 | auto LT = GV->getLinkage(); |
586 | return !(GlobalValue::isPrivateLinkage(LT) || |
587 | GlobalValue::isInternalLinkage(LT)); |
588 | }; |
589 | |
590 | // Use the names to distinguish the two values, but only if the |
591 | // names are semantically important. |
592 | if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV)) |
593 | return LGV->getName().compare(RGV->getName()); |
594 | } |
595 | |
596 | // For instructions, compare their loop depth, and their operand count. This |
597 | // is pretty loose. |
598 | if (const auto *LInst = dyn_cast<Instruction>(LV)) { |
599 | const auto *RInst = cast<Instruction>(RV); |
600 | |
601 | // Compare loop depths. |
602 | const BasicBlock *LParent = LInst->getParent(), |
603 | *RParent = RInst->getParent(); |
604 | if (LParent != RParent) { |
605 | unsigned LDepth = LI->getLoopDepth(LParent), |
606 | RDepth = LI->getLoopDepth(RParent); |
607 | if (LDepth != RDepth) |
608 | return (int)LDepth - (int)RDepth; |
609 | } |
610 | |
611 | // Compare the number of operands. |
612 | unsigned LNumOps = LInst->getNumOperands(), |
613 | RNumOps = RInst->getNumOperands(); |
614 | if (LNumOps != RNumOps) |
615 | return (int)LNumOps - (int)RNumOps; |
616 | |
617 | for (unsigned Idx : seq(0u, LNumOps)) { |
618 | int Result = |
619 | CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx), |
620 | RInst->getOperand(Idx), Depth + 1); |
621 | if (Result != 0) |
622 | return Result; |
623 | } |
624 | } |
625 | |
626 | EqCacheValue.unionSets(LV, RV); |
627 | return 0; |
628 | } |
629 | |
630 | // Return negative, zero, or positive, if LHS is less than, equal to, or greater |
631 | // than RHS, respectively. A three-way result allows recursive comparisons to be |
632 | // more efficient. |
633 | static int CompareSCEVComplexity( |
634 | EquivalenceClasses<const SCEV *> &EqCacheSCEV, |
635 | EquivalenceClasses<const Value *> &EqCacheValue, |
636 | const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS, |
637 | DominatorTree &DT, unsigned Depth = 0) { |
638 | // Fast-path: SCEVs are uniqued so we can do a quick equality check. |
639 | if (LHS == RHS) |
640 | return 0; |
641 | |
642 | // Primarily, sort the SCEVs by their getSCEVType(). |
643 | unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType(); |
644 | if (LType != RType) |
645 | return (int)LType - (int)RType; |
646 | |
647 | if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.isEquivalent(LHS, RHS)) |
648 | return 0; |
649 | // Aside from the getSCEVType() ordering, the particular ordering |
650 | // isn't very important except that it's beneficial to be consistent, |
651 | // so that (a + b) and (b + a) don't end up as different expressions. |
652 | switch (static_cast<SCEVTypes>(LType)) { |
653 | case scUnknown: { |
654 | const SCEVUnknown *LU = cast<SCEVUnknown>(LHS); |
655 | const SCEVUnknown *RU = cast<SCEVUnknown>(RHS); |
656 | |
657 | int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(), |
658 | RU->getValue(), Depth + 1); |
659 | if (X == 0) |
660 | EqCacheSCEV.unionSets(LHS, RHS); |
661 | return X; |
662 | } |
663 | |
664 | case scConstant: { |
665 | const SCEVConstant *LC = cast<SCEVConstant>(LHS); |
666 | const SCEVConstant *RC = cast<SCEVConstant>(RHS); |
667 | |
668 | // Compare constant values. |
669 | const APInt &LA = LC->getAPInt(); |
670 | const APInt &RA = RC->getAPInt(); |
671 | unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth(); |
672 | if (LBitWidth != RBitWidth) |
673 | return (int)LBitWidth - (int)RBitWidth; |
674 | return LA.ult(RA) ? -1 : 1; |
675 | } |
676 | |
677 | case scAddRecExpr: { |
678 | const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS); |
679 | const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS); |
680 | |
681 | // There is always a dominance between two recs that are used by one SCEV, |
682 | // so we can safely sort recs by loop header dominance. We require such |
683 | // order in getAddExpr. |
684 | const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop(); |
685 | if (LLoop != RLoop) { |
686 | const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader(); |
687 | assert(LHead != RHead && "Two loops share the same header?")((LHead != RHead && "Two loops share the same header?" ) ? static_cast<void> (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 687, __PRETTY_FUNCTION__)); |
688 | if (DT.dominates(LHead, RHead)) |
689 | return 1; |
690 | else |
691 | assert(DT.dominates(RHead, LHead) &&((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 692, __PRETTY_FUNCTION__)) |
692 | "No dominance between recurrences used by one SCEV?")((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 692, __PRETTY_FUNCTION__)); |
693 | return -1; |
694 | } |
695 | |
696 | // Addrec complexity grows with operand count. |
697 | unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands(); |
698 | if (LNumOps != RNumOps) |
699 | return (int)LNumOps - (int)RNumOps; |
700 | |
701 | // Lexicographically compare. |
702 | for (unsigned i = 0; i != LNumOps; ++i) { |
703 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, |
704 | LA->getOperand(i), RA->getOperand(i), DT, |
705 | Depth + 1); |
706 | if (X != 0) |
707 | return X; |
708 | } |
709 | EqCacheSCEV.unionSets(LHS, RHS); |
710 | return 0; |
711 | } |
712 | |
713 | case scAddExpr: |
714 | case scMulExpr: |
715 | case scSMaxExpr: |
716 | case scUMaxExpr: { |
717 | const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS); |
718 | const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS); |
719 | |
720 | // Lexicographically compare n-ary expressions. |
721 | unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands(); |
722 | if (LNumOps != RNumOps) |
723 | return (int)LNumOps - (int)RNumOps; |
724 | |
725 | for (unsigned i = 0; i != LNumOps; ++i) { |
726 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, |
727 | LC->getOperand(i), RC->getOperand(i), DT, |
728 | Depth + 1); |
729 | if (X != 0) |
730 | return X; |
731 | } |
732 | EqCacheSCEV.unionSets(LHS, RHS); |
733 | return 0; |
734 | } |
735 | |
736 | case scUDivExpr: { |
737 | const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS); |
738 | const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS); |
739 | |
740 | // Lexicographically compare udiv expressions. |
741 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(), |
742 | RC->getLHS(), DT, Depth + 1); |
743 | if (X != 0) |
744 | return X; |
745 | X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(), |
746 | RC->getRHS(), DT, Depth + 1); |
747 | if (X == 0) |
748 | EqCacheSCEV.unionSets(LHS, RHS); |
749 | return X; |
750 | } |
751 | |
752 | case scTruncate: |
753 | case scZeroExtend: |
754 | case scSignExtend: { |
755 | const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS); |
756 | const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS); |
757 | |
758 | // Compare cast expressions by operand. |
759 | int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, |
760 | LC->getOperand(), RC->getOperand(), DT, |
761 | Depth + 1); |
762 | if (X == 0) |
763 | EqCacheSCEV.unionSets(LHS, RHS); |
764 | return X; |
765 | } |
766 | |
767 | case scCouldNotCompute: |
768 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 768); |
769 | } |
770 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 770); |
771 | } |
772 | |
773 | /// Given a list of SCEV objects, order them by their complexity, and group |
774 | /// objects of the same complexity together by value. When this routine is |
775 | /// finished, we know that any duplicates in the vector are consecutive and that |
776 | /// complexity is monotonically increasing. |
777 | /// |
778 | /// Note that we go take special precautions to ensure that we get deterministic |
779 | /// results from this routine. In other words, we don't want the results of |
780 | /// this to depend on where the addresses of various SCEV objects happened to |
781 | /// land in memory. |
782 | static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops, |
783 | LoopInfo *LI, DominatorTree &DT) { |
784 | if (Ops.size() < 2) return; // Noop |
785 | |
786 | EquivalenceClasses<const SCEV *> EqCacheSCEV; |
787 | EquivalenceClasses<const Value *> EqCacheValue; |
788 | if (Ops.size() == 2) { |
789 | // This is the common case, which also happens to be trivially simple. |
790 | // Special case it. |
791 | const SCEV *&LHS = Ops[0], *&RHS = Ops[1]; |
792 | if (CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, RHS, LHS, DT) < 0) |
793 | std::swap(LHS, RHS); |
794 | return; |
795 | } |
796 | |
797 | // Do the rough sort by complexity. |
798 | std::stable_sort(Ops.begin(), Ops.end(), |
799 | [&](const SCEV *LHS, const SCEV *RHS) { |
800 | return CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, |
801 | LHS, RHS, DT) < 0; |
802 | }); |
803 | |
804 | // Now that we are sorted by complexity, group elements of the same |
805 | // complexity. Note that this is, at worst, N^2, but the vector is likely to |
806 | // be extremely short in practice. Note that we take this approach because we |
807 | // do not want to depend on the addresses of the objects we are grouping. |
808 | for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) { |
809 | const SCEV *S = Ops[i]; |
810 | unsigned Complexity = S->getSCEVType(); |
811 | |
812 | // If there are any objects of the same complexity and same value as this |
813 | // one, group them. |
814 | for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) { |
815 | if (Ops[j] == S) { // Found a duplicate. |
816 | // Move it to immediately after i'th element. |
817 | std::swap(Ops[i+1], Ops[j]); |
818 | ++i; // no need to rescan it. |
819 | if (i == e-2) return; // Done! |
820 | } |
821 | } |
822 | } |
823 | } |
824 | |
825 | // Returns the size of the SCEV S. |
826 | static inline int sizeOfSCEV(const SCEV *S) { |
827 | struct FindSCEVSize { |
828 | int Size = 0; |
829 | |
830 | FindSCEVSize() = default; |
831 | |
832 | bool follow(const SCEV *S) { |
833 | ++Size; |
834 | // Keep looking at all operands of S. |
835 | return true; |
836 | } |
837 | |
838 | bool isDone() const { |
839 | return false; |
840 | } |
841 | }; |
842 | |
843 | FindSCEVSize F; |
844 | SCEVTraversal<FindSCEVSize> ST(F); |
845 | ST.visitAll(S); |
846 | return F.Size; |
847 | } |
848 | |
849 | namespace { |
850 | |
851 | struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> { |
852 | public: |
853 | // Computes the Quotient and Remainder of the division of Numerator by |
854 | // Denominator. |
855 | static void divide(ScalarEvolution &SE, const SCEV *Numerator, |
856 | const SCEV *Denominator, const SCEV **Quotient, |
857 | const SCEV **Remainder) { |
858 | assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV" ) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 858, __PRETTY_FUNCTION__)); |
859 | |
860 | SCEVDivision D(SE, Numerator, Denominator); |
861 | |
862 | // Check for the trivial case here to avoid having to check for it in the |
863 | // rest of the code. |
864 | if (Numerator == Denominator) { |
865 | *Quotient = D.One; |
866 | *Remainder = D.Zero; |
867 | return; |
868 | } |
869 | |
870 | if (Numerator->isZero()) { |
871 | *Quotient = D.Zero; |
872 | *Remainder = D.Zero; |
873 | return; |
874 | } |
875 | |
876 | // A simple case when N/1. The quotient is N. |
877 | if (Denominator->isOne()) { |
878 | *Quotient = Numerator; |
879 | *Remainder = D.Zero; |
880 | return; |
881 | } |
882 | |
883 | // Split the Denominator when it is a product. |
884 | if (const SCEVMulExpr *T = dyn_cast<SCEVMulExpr>(Denominator)) { |
885 | const SCEV *Q, *R; |
886 | *Quotient = Numerator; |
887 | for (const SCEV *Op : T->operands()) { |
888 | divide(SE, *Quotient, Op, &Q, &R); |
889 | *Quotient = Q; |
890 | |
891 | // Bail out when the Numerator is not divisible by one of the terms of |
892 | // the Denominator. |
893 | if (!R->isZero()) { |
894 | *Quotient = D.Zero; |
895 | *Remainder = Numerator; |
896 | return; |
897 | } |
898 | } |
899 | *Remainder = D.Zero; |
900 | return; |
901 | } |
902 | |
903 | D.visit(Numerator); |
904 | *Quotient = D.Quotient; |
905 | *Remainder = D.Remainder; |
906 | } |
907 | |
908 | // Except in the trivial case described above, we do not know how to divide |
909 | // Expr by Denominator for the following functions with empty implementation. |
910 | void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {} |
911 | void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {} |
912 | void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {} |
913 | void visitUDivExpr(const SCEVUDivExpr *Numerator) {} |
914 | void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {} |
915 | void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {} |
916 | void visitUnknown(const SCEVUnknown *Numerator) {} |
917 | void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {} |
918 | |
919 | void visitConstant(const SCEVConstant *Numerator) { |
920 | if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) { |
921 | APInt NumeratorVal = Numerator->getAPInt(); |
922 | APInt DenominatorVal = D->getAPInt(); |
923 | uint32_t NumeratorBW = NumeratorVal.getBitWidth(); |
924 | uint32_t DenominatorBW = DenominatorVal.getBitWidth(); |
925 | |
926 | if (NumeratorBW > DenominatorBW) |
927 | DenominatorVal = DenominatorVal.sext(NumeratorBW); |
928 | else if (NumeratorBW < DenominatorBW) |
929 | NumeratorVal = NumeratorVal.sext(DenominatorBW); |
930 | |
931 | APInt QuotientVal(NumeratorVal.getBitWidth(), 0); |
932 | APInt RemainderVal(NumeratorVal.getBitWidth(), 0); |
933 | APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal); |
934 | Quotient = SE.getConstant(QuotientVal); |
935 | Remainder = SE.getConstant(RemainderVal); |
936 | return; |
937 | } |
938 | } |
939 | |
940 | void visitAddRecExpr(const SCEVAddRecExpr *Numerator) { |
941 | const SCEV *StartQ, *StartR, *StepQ, *StepR; |
942 | if (!Numerator->isAffine()) |
943 | return cannotDivide(Numerator); |
944 | divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR); |
945 | divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR); |
946 | // Bail out if the types do not match. |
947 | Type *Ty = Denominator->getType(); |
948 | if (Ty != StartQ->getType() || Ty != StartR->getType() || |
949 | Ty != StepQ->getType() || Ty != StepR->getType()) |
950 | return cannotDivide(Numerator); |
951 | Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(), |
952 | Numerator->getNoWrapFlags()); |
953 | Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(), |
954 | Numerator->getNoWrapFlags()); |
955 | } |
956 | |
957 | void visitAddExpr(const SCEVAddExpr *Numerator) { |
958 | SmallVector<const SCEV *, 2> Qs, Rs; |
959 | Type *Ty = Denominator->getType(); |
960 | |
961 | for (const SCEV *Op : Numerator->operands()) { |
962 | const SCEV *Q, *R; |
963 | divide(SE, Op, Denominator, &Q, &R); |
964 | |
965 | // Bail out if types do not match. |
966 | if (Ty != Q->getType() || Ty != R->getType()) |
967 | return cannotDivide(Numerator); |
968 | |
969 | Qs.push_back(Q); |
970 | Rs.push_back(R); |
971 | } |
972 | |
973 | if (Qs.size() == 1) { |
974 | Quotient = Qs[0]; |
975 | Remainder = Rs[0]; |
976 | return; |
977 | } |
978 | |
979 | Quotient = SE.getAddExpr(Qs); |
980 | Remainder = SE.getAddExpr(Rs); |
981 | } |
982 | |
983 | void visitMulExpr(const SCEVMulExpr *Numerator) { |
984 | SmallVector<const SCEV *, 2> Qs; |
985 | Type *Ty = Denominator->getType(); |
986 | |
987 | bool FoundDenominatorTerm = false; |
988 | for (const SCEV *Op : Numerator->operands()) { |
989 | // Bail out if types do not match. |
990 | if (Ty != Op->getType()) |
991 | return cannotDivide(Numerator); |
992 | |
993 | if (FoundDenominatorTerm) { |
994 | Qs.push_back(Op); |
995 | continue; |
996 | } |
997 | |
998 | // Check whether Denominator divides one of the product operands. |
999 | const SCEV *Q, *R; |
1000 | divide(SE, Op, Denominator, &Q, &R); |
1001 | if (!R->isZero()) { |
1002 | Qs.push_back(Op); |
1003 | continue; |
1004 | } |
1005 | |
1006 | // Bail out if types do not match. |
1007 | if (Ty != Q->getType()) |
1008 | return cannotDivide(Numerator); |
1009 | |
1010 | FoundDenominatorTerm = true; |
1011 | Qs.push_back(Q); |
1012 | } |
1013 | |
1014 | if (FoundDenominatorTerm) { |
1015 | Remainder = Zero; |
1016 | if (Qs.size() == 1) |
1017 | Quotient = Qs[0]; |
1018 | else |
1019 | Quotient = SE.getMulExpr(Qs); |
1020 | return; |
1021 | } |
1022 | |
1023 | if (!isa<SCEVUnknown>(Denominator)) |
1024 | return cannotDivide(Numerator); |
1025 | |
1026 | // The Remainder is obtained by replacing Denominator by 0 in Numerator. |
1027 | ValueToValueMap RewriteMap; |
1028 | RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] = |
1029 | cast<SCEVConstant>(Zero)->getValue(); |
1030 | Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true); |
1031 | |
1032 | if (Remainder->isZero()) { |
1033 | // The Quotient is obtained by replacing Denominator by 1 in Numerator. |
1034 | RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] = |
1035 | cast<SCEVConstant>(One)->getValue(); |
1036 | Quotient = |
1037 | SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true); |
1038 | return; |
1039 | } |
1040 | |
1041 | // Quotient is (Numerator - Remainder) divided by Denominator. |
1042 | const SCEV *Q, *R; |
1043 | const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder); |
1044 | // This SCEV does not seem to simplify: fail the division here. |
1045 | if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator)) |
1046 | return cannotDivide(Numerator); |
1047 | divide(SE, Diff, Denominator, &Q, &R); |
1048 | if (R != Zero) |
1049 | return cannotDivide(Numerator); |
1050 | Quotient = Q; |
1051 | } |
1052 | |
1053 | private: |
1054 | SCEVDivision(ScalarEvolution &S, const SCEV *Numerator, |
1055 | const SCEV *Denominator) |
1056 | : SE(S), Denominator(Denominator) { |
1057 | Zero = SE.getZero(Denominator->getType()); |
1058 | One = SE.getOne(Denominator->getType()); |
1059 | |
1060 | // We generally do not know how to divide Expr by Denominator. We |
1061 | // initialize the division to a "cannot divide" state to simplify the rest |
1062 | // of the code. |
1063 | cannotDivide(Numerator); |
1064 | } |
1065 | |
1066 | // Convenience function for giving up on the division. We set the quotient to |
1067 | // be equal to zero and the remainder to be equal to the numerator. |
1068 | void cannotDivide(const SCEV *Numerator) { |
1069 | Quotient = Zero; |
1070 | Remainder = Numerator; |
1071 | } |
1072 | |
1073 | ScalarEvolution &SE; |
1074 | const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One; |
1075 | }; |
1076 | |
1077 | } // end anonymous namespace |
1078 | |
1079 | //===----------------------------------------------------------------------===// |
1080 | // Simple SCEV method implementations |
1081 | //===----------------------------------------------------------------------===// |
1082 | |
1083 | /// Compute BC(It, K). The result has width W. Assume, K > 0. |
1084 | static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K, |
1085 | ScalarEvolution &SE, |
1086 | Type *ResultTy) { |
1087 | // Handle the simplest case efficiently. |
1088 | if (K == 1) |
1089 | return SE.getTruncateOrZeroExtend(It, ResultTy); |
1090 | |
1091 | // We are using the following formula for BC(It, K): |
1092 | // |
1093 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K! |
1094 | // |
1095 | // Suppose, W is the bitwidth of the return value. We must be prepared for |
1096 | // overflow. Hence, we must assure that the result of our computation is |
1097 | // equal to the accurate one modulo 2^W. Unfortunately, division isn't |
1098 | // safe in modular arithmetic. |
1099 | // |
1100 | // However, this code doesn't use exactly that formula; the formula it uses |
1101 | // is something like the following, where T is the number of factors of 2 in |
1102 | // K! (i.e. trailing zeros in the binary representation of K!), and ^ is |
1103 | // exponentiation: |
1104 | // |
1105 | // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T) |
1106 | // |
1107 | // This formula is trivially equivalent to the previous formula. However, |
1108 | // this formula can be implemented much more efficiently. The trick is that |
1109 | // K! / 2^T is odd, and exact division by an odd number *is* safe in modular |
1110 | // arithmetic. To do exact division in modular arithmetic, all we have |
1111 | // to do is multiply by the inverse. Therefore, this step can be done at |
1112 | // width W. |
1113 | // |
1114 | // The next issue is how to safely do the division by 2^T. The way this |
1115 | // is done is by doing the multiplication step at a width of at least W + T |
1116 | // bits. This way, the bottom W+T bits of the product are accurate. Then, |
1117 | // when we perform the division by 2^T (which is equivalent to a right shift |
1118 | // by T), the bottom W bits are accurate. Extra bits are okay; they'll get |
1119 | // truncated out after the division by 2^T. |
1120 | // |
1121 | // In comparison to just directly using the first formula, this technique |
1122 | // is much more efficient; using the first formula requires W * K bits, |
1123 | // but this formula less than W + K bits. Also, the first formula requires |
1124 | // a division step, whereas this formula only requires multiplies and shifts. |
1125 | // |
1126 | // It doesn't matter whether the subtraction step is done in the calculation |
1127 | // width or the input iteration count's width; if the subtraction overflows, |
1128 | // the result must be zero anyway. We prefer here to do it in the width of |
1129 | // the induction variable because it helps a lot for certain cases; CodeGen |
1130 | // isn't smart enough to ignore the overflow, which leads to much less |
1131 | // efficient code if the width of the subtraction is wider than the native |
1132 | // register width. |
1133 | // |
1134 | // (It's possible to not widen at all by pulling out factors of 2 before |
1135 | // the multiplication; for example, K=2 can be calculated as |
1136 | // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires |
1137 | // extra arithmetic, so it's not an obvious win, and it gets |
1138 | // much more complicated for K > 3.) |
1139 | |
1140 | // Protection from insane SCEVs; this bound is conservative, |
1141 | // but it probably doesn't matter. |
1142 | if (K > 1000) |
1143 | return SE.getCouldNotCompute(); |
1144 | |
1145 | unsigned W = SE.getTypeSizeInBits(ResultTy); |
1146 | |
1147 | // Calculate K! / 2^T and T; we divide out the factors of two before |
1148 | // multiplying for calculating K! / 2^T to avoid overflow. |
1149 | // Other overflow doesn't matter because we only care about the bottom |
1150 | // W bits of the result. |
1151 | APInt OddFactorial(W, 1); |
1152 | unsigned T = 1; |
1153 | for (unsigned i = 3; i <= K; ++i) { |
1154 | APInt Mult(W, i); |
1155 | unsigned TwoFactors = Mult.countTrailingZeros(); |
1156 | T += TwoFactors; |
1157 | Mult.lshrInPlace(TwoFactors); |
1158 | OddFactorial *= Mult; |
1159 | } |
1160 | |
1161 | // We need at least W + T bits for the multiplication step |
1162 | unsigned CalculationBits = W + T; |
1163 | |
1164 | // Calculate 2^T, at width T+W. |
1165 | APInt DivFactor = APInt::getOneBitSet(CalculationBits, T); |
1166 | |
1167 | // Calculate the multiplicative inverse of K! / 2^T; |
1168 | // this multiplication factor will perform the exact division by |
1169 | // K! / 2^T. |
1170 | APInt Mod = APInt::getSignedMinValue(W+1); |
1171 | APInt MultiplyFactor = OddFactorial.zext(W+1); |
1172 | MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod); |
1173 | MultiplyFactor = MultiplyFactor.trunc(W); |
1174 | |
1175 | // Calculate the product, at width T+W |
1176 | IntegerType *CalculationTy = IntegerType::get(SE.getContext(), |
1177 | CalculationBits); |
1178 | const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy); |
1179 | for (unsigned i = 1; i != K; ++i) { |
1180 | const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i)); |
1181 | Dividend = SE.getMulExpr(Dividend, |
1182 | SE.getTruncateOrZeroExtend(S, CalculationTy)); |
1183 | } |
1184 | |
1185 | // Divide by 2^T |
1186 | const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor)); |
1187 | |
1188 | // Truncate the result, and divide by K! / 2^T. |
1189 | |
1190 | return SE.getMulExpr(SE.getConstant(MultiplyFactor), |
1191 | SE.getTruncateOrZeroExtend(DivResult, ResultTy)); |
1192 | } |
1193 | |
1194 | /// Return the value of this chain of recurrences at the specified iteration |
1195 | /// number. We can evaluate this recurrence by multiplying each element in the |
1196 | /// chain by the binomial coefficient corresponding to it. In other words, we |
1197 | /// can evaluate {A,+,B,+,C,+,D} as: |
1198 | /// |
1199 | /// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3) |
1200 | /// |
1201 | /// where BC(It, k) stands for binomial coefficient. |
1202 | const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It, |
1203 | ScalarEvolution &SE) const { |
1204 | const SCEV *Result = getStart(); |
1205 | for (unsigned i = 1, e = getNumOperands(); i != e; ++i) { |
1206 | // The computation is correct in the face of overflow provided that the |
1207 | // multiplication is performed _after_ the evaluation of the binomial |
1208 | // coefficient. |
1209 | const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType()); |
1210 | if (isa<SCEVCouldNotCompute>(Coeff)) |
1211 | return Coeff; |
1212 | |
1213 | Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff)); |
1214 | } |
1215 | return Result; |
1216 | } |
1217 | |
1218 | //===----------------------------------------------------------------------===// |
1219 | // SCEV Expression folder implementations |
1220 | //===----------------------------------------------------------------------===// |
1221 | |
1222 | const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, |
1223 | Type *Ty) { |
1224 | assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits( Ty) && "This is not a truncating conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1225, __PRETTY_FUNCTION__)) |
1225 | "This is not a truncating conversion!")((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits( Ty) && "This is not a truncating conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1225, __PRETTY_FUNCTION__)); |
1226 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1227, __PRETTY_FUNCTION__)) |
1227 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1227, __PRETTY_FUNCTION__)); |
1228 | Ty = getEffectiveSCEVType(Ty); |
1229 | |
1230 | FoldingSetNodeID ID; |
1231 | ID.AddInteger(scTruncate); |
1232 | ID.AddPointer(Op); |
1233 | ID.AddPointer(Ty); |
1234 | void *IP = nullptr; |
1235 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
1236 | |
1237 | // Fold if the operand is constant. |
1238 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
1239 | return getConstant( |
1240 | cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty))); |
1241 | |
1242 | // trunc(trunc(x)) --> trunc(x) |
1243 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) |
1244 | return getTruncateExpr(ST->getOperand(), Ty); |
1245 | |
1246 | // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing |
1247 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) |
1248 | return getTruncateOrSignExtend(SS->getOperand(), Ty); |
1249 | |
1250 | // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing |
1251 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
1252 | return getTruncateOrZeroExtend(SZ->getOperand(), Ty); |
1253 | |
1254 | // trunc(x1 + ... + xN) --> trunc(x1) + ... + trunc(xN) and |
1255 | // trunc(x1 * ... * xN) --> trunc(x1) * ... * trunc(xN), |
1256 | // if after transforming we have at most one truncate, not counting truncates |
1257 | // that replace other casts. |
1258 | if (isa<SCEVAddExpr>(Op) || isa<SCEVMulExpr>(Op)) { |
1259 | auto *CommOp = cast<SCEVCommutativeExpr>(Op); |
1260 | SmallVector<const SCEV *, 4> Operands; |
1261 | unsigned numTruncs = 0; |
1262 | for (unsigned i = 0, e = CommOp->getNumOperands(); i != e && numTruncs < 2; |
1263 | ++i) { |
1264 | const SCEV *S = getTruncateExpr(CommOp->getOperand(i), Ty); |
1265 | if (!isa<SCEVCastExpr>(CommOp->getOperand(i)) && isa<SCEVTruncateExpr>(S)) |
1266 | numTruncs++; |
1267 | Operands.push_back(S); |
1268 | } |
1269 | if (numTruncs < 2) { |
1270 | if (isa<SCEVAddExpr>(Op)) |
1271 | return getAddExpr(Operands); |
1272 | else if (isa<SCEVMulExpr>(Op)) |
1273 | return getMulExpr(Operands); |
1274 | else |
1275 | llvm_unreachable("Unexpected SCEV type for Op.")::llvm::llvm_unreachable_internal("Unexpected SCEV type for Op." , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1275); |
1276 | } |
1277 | // Although we checked in the beginning that ID is not in the cache, it is |
1278 | // possible that during recursion and different modification ID was inserted |
1279 | // into the cache. So if we find it, just return it. |
1280 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) |
1281 | return S; |
1282 | } |
1283 | |
1284 | // If the input value is a chrec scev, truncate the chrec's operands. |
1285 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { |
1286 | SmallVector<const SCEV *, 4> Operands; |
1287 | for (const SCEV *Op : AddRec->operands()) |
1288 | Operands.push_back(getTruncateExpr(Op, Ty)); |
1289 | return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap); |
1290 | } |
1291 | |
1292 | // The cast wasn't folded; create an explicit cast node. We can reuse |
1293 | // the existing insert position since if we get here, we won't have |
1294 | // made any changes which would invalidate it. |
1295 | SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator), |
1296 | Op, Ty); |
1297 | UniqueSCEVs.InsertNode(S, IP); |
1298 | addToLoopUseLists(S); |
1299 | return S; |
1300 | } |
1301 | |
1302 | // Get the limit of a recurrence such that incrementing by Step cannot cause |
1303 | // signed overflow as long as the value of the recurrence within the |
1304 | // loop does not exceed this limit before incrementing. |
1305 | static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step, |
1306 | ICmpInst::Predicate *Pred, |
1307 | ScalarEvolution *SE) { |
1308 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); |
1309 | if (SE->isKnownPositive(Step)) { |
1310 | *Pred = ICmpInst::ICMP_SLT; |
1311 | return SE->getConstant(APInt::getSignedMinValue(BitWidth) - |
1312 | SE->getSignedRangeMax(Step)); |
1313 | } |
1314 | if (SE->isKnownNegative(Step)) { |
1315 | *Pred = ICmpInst::ICMP_SGT; |
1316 | return SE->getConstant(APInt::getSignedMaxValue(BitWidth) - |
1317 | SE->getSignedRangeMin(Step)); |
1318 | } |
1319 | return nullptr; |
1320 | } |
1321 | |
1322 | // Get the limit of a recurrence such that incrementing by Step cannot cause |
1323 | // unsigned overflow as long as the value of the recurrence within the loop does |
1324 | // not exceed this limit before incrementing. |
1325 | static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step, |
1326 | ICmpInst::Predicate *Pred, |
1327 | ScalarEvolution *SE) { |
1328 | unsigned BitWidth = SE->getTypeSizeInBits(Step->getType()); |
1329 | *Pred = ICmpInst::ICMP_ULT; |
1330 | |
1331 | return SE->getConstant(APInt::getMinValue(BitWidth) - |
1332 | SE->getUnsignedRangeMax(Step)); |
1333 | } |
1334 | |
1335 | namespace { |
1336 | |
1337 | struct ExtendOpTraitsBase { |
1338 | typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *, |
1339 | unsigned); |
1340 | }; |
1341 | |
1342 | // Used to make code generic over signed and unsigned overflow. |
1343 | template <typename ExtendOp> struct ExtendOpTraits { |
1344 | // Members present: |
1345 | // |
1346 | // static const SCEV::NoWrapFlags WrapType; |
1347 | // |
1348 | // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr; |
1349 | // |
1350 | // static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
1351 | // ICmpInst::Predicate *Pred, |
1352 | // ScalarEvolution *SE); |
1353 | }; |
1354 | |
1355 | template <> |
1356 | struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase { |
1357 | static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW; |
1358 | |
1359 | static const GetExtendExprTy GetExtendExpr; |
1360 | |
1361 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
1362 | ICmpInst::Predicate *Pred, |
1363 | ScalarEvolution *SE) { |
1364 | return getSignedOverflowLimitForStep(Step, Pred, SE); |
1365 | } |
1366 | }; |
1367 | |
1368 | const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits< |
1369 | SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr; |
1370 | |
1371 | template <> |
1372 | struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase { |
1373 | static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW; |
1374 | |
1375 | static const GetExtendExprTy GetExtendExpr; |
1376 | |
1377 | static const SCEV *getOverflowLimitForStep(const SCEV *Step, |
1378 | ICmpInst::Predicate *Pred, |
1379 | ScalarEvolution *SE) { |
1380 | return getUnsignedOverflowLimitForStep(Step, Pred, SE); |
1381 | } |
1382 | }; |
1383 | |
1384 | const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits< |
1385 | SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr; |
1386 | |
1387 | } // end anonymous namespace |
1388 | |
1389 | // The recurrence AR has been shown to have no signed/unsigned wrap or something |
1390 | // close to it. Typically, if we can prove NSW/NUW for AR, then we can just as |
1391 | // easily prove NSW/NUW for its preincrement or postincrement sibling. This |
1392 | // allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step + |
1393 | // Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the |
1394 | // expression "Step + sext/zext(PreIncAR)" is congruent with |
1395 | // "sext/zext(PostIncAR)" |
1396 | template <typename ExtendOpTy> |
1397 | static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty, |
1398 | ScalarEvolution *SE, unsigned Depth) { |
1399 | auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType; |
1400 | auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr; |
1401 | |
1402 | const Loop *L = AR->getLoop(); |
1403 | const SCEV *Start = AR->getStart(); |
1404 | const SCEV *Step = AR->getStepRecurrence(*SE); |
1405 | |
1406 | // Check for a simple looking step prior to loop entry. |
1407 | const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start); |
1408 | if (!SA) |
1409 | return nullptr; |
1410 | |
1411 | // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV |
1412 | // subtraction is expensive. For this purpose, perform a quick and dirty |
1413 | // difference, by checking for Step in the operand list. |
1414 | SmallVector<const SCEV *, 4> DiffOps; |
1415 | for (const SCEV *Op : SA->operands()) |
1416 | if (Op != Step) |
1417 | DiffOps.push_back(Op); |
1418 | |
1419 | if (DiffOps.size() == SA->getNumOperands()) |
1420 | return nullptr; |
1421 | |
1422 | // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` + |
1423 | // `Step`: |
1424 | |
1425 | // 1. NSW/NUW flags on the step increment. |
1426 | auto PreStartFlags = |
1427 | ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW); |
1428 | const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags); |
1429 | const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>( |
1430 | SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap)); |
1431 | |
1432 | // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies |
1433 | // "S+X does not sign/unsign-overflow". |
1434 | // |
1435 | |
1436 | const SCEV *BECount = SE->getBackedgeTakenCount(L); |
1437 | if (PreAR && PreAR->getNoWrapFlags(WrapType) && |
1438 | !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount)) |
1439 | return PreStart; |
1440 | |
1441 | // 2. Direct overflow check on the step operation's expression. |
1442 | unsigned BitWidth = SE->getTypeSizeInBits(AR->getType()); |
1443 | Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2); |
1444 | const SCEV *OperandExtendedStart = |
1445 | SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth), |
1446 | (SE->*GetExtendExpr)(Step, WideTy, Depth)); |
1447 | if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) { |
1448 | if (PreAR && AR->getNoWrapFlags(WrapType)) { |
1449 | // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW |
1450 | // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then |
1451 | // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact. |
1452 | const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType); |
1453 | } |
1454 | return PreStart; |
1455 | } |
1456 | |
1457 | // 3. Loop precondition. |
1458 | ICmpInst::Predicate Pred; |
1459 | const SCEV *OverflowLimit = |
1460 | ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE); |
1461 | |
1462 | if (OverflowLimit && |
1463 | SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit)) |
1464 | return PreStart; |
1465 | |
1466 | return nullptr; |
1467 | } |
1468 | |
1469 | // Get the normalized zero or sign extended expression for this AddRec's Start. |
1470 | template <typename ExtendOpTy> |
1471 | static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty, |
1472 | ScalarEvolution *SE, |
1473 | unsigned Depth) { |
1474 | auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr; |
1475 | |
1476 | const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth); |
1477 | if (!PreStart) |
1478 | return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth); |
1479 | |
1480 | return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty, |
1481 | Depth), |
1482 | (SE->*GetExtendExpr)(PreStart, Ty, Depth)); |
1483 | } |
1484 | |
1485 | // Try to prove away overflow by looking at "nearby" add recurrences. A |
1486 | // motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it |
1487 | // does not itself wrap then we can conclude that `{1,+,4}` is `nuw`. |
1488 | // |
1489 | // Formally: |
1490 | // |
1491 | // {S,+,X} == {S-T,+,X} + T |
1492 | // => Ext({S,+,X}) == Ext({S-T,+,X} + T) |
1493 | // |
1494 | // If ({S-T,+,X} + T) does not overflow ... (1) |
1495 | // |
1496 | // RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T) |
1497 | // |
1498 | // If {S-T,+,X} does not overflow ... (2) |
1499 | // |
1500 | // RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T) |
1501 | // == {Ext(S-T)+Ext(T),+,Ext(X)} |
1502 | // |
1503 | // If (S-T)+T does not overflow ... (3) |
1504 | // |
1505 | // RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)} |
1506 | // == {Ext(S),+,Ext(X)} == LHS |
1507 | // |
1508 | // Thus, if (1), (2) and (3) are true for some T, then |
1509 | // Ext({S,+,X}) == {Ext(S),+,Ext(X)} |
1510 | // |
1511 | // (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T) |
1512 | // does not overflow" restricted to the 0th iteration. Therefore we only need |
1513 | // to check for (1) and (2). |
1514 | // |
1515 | // In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T |
1516 | // is `Delta` (defined below). |
1517 | template <typename ExtendOpTy> |
1518 | bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start, |
1519 | const SCEV *Step, |
1520 | const Loop *L) { |
1521 | auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType; |
1522 | |
1523 | // We restrict `Start` to a constant to prevent SCEV from spending too much |
1524 | // time here. It is correct (but more expensive) to continue with a |
1525 | // non-constant `Start` and do a general SCEV subtraction to compute |
1526 | // `PreStart` below. |
1527 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start); |
1528 | if (!StartC) |
1529 | return false; |
1530 | |
1531 | APInt StartAI = StartC->getAPInt(); |
1532 | |
1533 | for (unsigned Delta : {-2, -1, 1, 2}) { |
1534 | const SCEV *PreStart = getConstant(StartAI - Delta); |
1535 | |
1536 | FoldingSetNodeID ID; |
1537 | ID.AddInteger(scAddRecExpr); |
1538 | ID.AddPointer(PreStart); |
1539 | ID.AddPointer(Step); |
1540 | ID.AddPointer(L); |
1541 | void *IP = nullptr; |
1542 | const auto *PreAR = |
1543 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
1544 | |
1545 | // Give up if we don't already have the add recurrence we need because |
1546 | // actually constructing an add recurrence is relatively expensive. |
1547 | if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2) |
1548 | const SCEV *DeltaS = getConstant(StartC->getType(), Delta); |
1549 | ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE; |
1550 | const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep( |
1551 | DeltaS, &Pred, this); |
1552 | if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1) |
1553 | return true; |
1554 | } |
1555 | } |
1556 | |
1557 | return false; |
1558 | } |
1559 | |
1560 | // Finds an integer D for an expression (C + x + y + ...) such that the top |
1561 | // level addition in (D + (C - D + x + y + ...)) would not wrap (signed or |
1562 | // unsigned) and the number of trailing zeros of (C - D + x + y + ...) is |
1563 | // maximized, where C is the \p ConstantTerm, x, y, ... are arbitrary SCEVs, and |
1564 | // the (C + x + y + ...) expression is \p WholeAddExpr. |
1565 | static APInt extractConstantWithoutWrapping(ScalarEvolution &SE, |
1566 | const SCEVConstant *ConstantTerm, |
1567 | const SCEVAddExpr *WholeAddExpr) { |
1568 | const APInt C = ConstantTerm->getAPInt(); |
1569 | const unsigned BitWidth = C.getBitWidth(); |
1570 | // Find number of trailing zeros of (x + y + ...) w/o the C first: |
1571 | uint32_t TZ = BitWidth; |
1572 | for (unsigned I = 1, E = WholeAddExpr->getNumOperands(); I < E && TZ; ++I) |
1573 | TZ = std::min(TZ, SE.GetMinTrailingZeros(WholeAddExpr->getOperand(I))); |
1574 | if (TZ) { |
1575 | // Set D to be as many least significant bits of C as possible while still |
1576 | // guaranteeing that adding D to (C - D + x + y + ...) won't cause a wrap: |
1577 | return TZ < BitWidth ? C.trunc(TZ).zext(BitWidth) : C; |
1578 | } |
1579 | return APInt(BitWidth, 0); |
1580 | } |
1581 | |
1582 | // Finds an integer D for an affine AddRec expression {C,+,x} such that the top |
1583 | // level addition in (D + {C-D,+,x}) would not wrap (signed or unsigned) and the |
1584 | // number of trailing zeros of (C - D + x * n) is maximized, where C is the \p |
1585 | // ConstantStart, x is an arbitrary \p Step, and n is the loop trip count. |
1586 | static APInt extractConstantWithoutWrapping(ScalarEvolution &SE, |
1587 | const APInt &ConstantStart, |
1588 | const SCEV *Step) { |
1589 | const unsigned BitWidth = ConstantStart.getBitWidth(); |
1590 | const uint32_t TZ = SE.GetMinTrailingZeros(Step); |
1591 | if (TZ) |
1592 | return TZ < BitWidth ? ConstantStart.trunc(TZ).zext(BitWidth) |
1593 | : ConstantStart; |
1594 | return APInt(BitWidth, 0); |
1595 | } |
1596 | |
1597 | const SCEV * |
1598 | ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) { |
1599 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1600, __PRETTY_FUNCTION__)) |
1600 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1600, __PRETTY_FUNCTION__)); |
1601 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1602, __PRETTY_FUNCTION__)) |
1602 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1602, __PRETTY_FUNCTION__)); |
1603 | Ty = getEffectiveSCEVType(Ty); |
1604 | |
1605 | // Fold if the operand is constant. |
1606 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
1607 | return getConstant( |
1608 | cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty))); |
1609 | |
1610 | // zext(zext(x)) --> zext(x) |
1611 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
1612 | return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1); |
1613 | |
1614 | // Before doing any expensive analysis, check to see if we've already |
1615 | // computed a SCEV for this Op and Ty. |
1616 | FoldingSetNodeID ID; |
1617 | ID.AddInteger(scZeroExtend); |
1618 | ID.AddPointer(Op); |
1619 | ID.AddPointer(Ty); |
1620 | void *IP = nullptr; |
1621 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
1622 | if (Depth > MaxExtDepth) { |
1623 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), |
1624 | Op, Ty); |
1625 | UniqueSCEVs.InsertNode(S, IP); |
1626 | addToLoopUseLists(S); |
1627 | return S; |
1628 | } |
1629 | |
1630 | // zext(trunc(x)) --> zext(x) or x or trunc(x) |
1631 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { |
1632 | // It's possible the bits taken off by the truncate were all zero bits. If |
1633 | // so, we should be able to simplify this further. |
1634 | const SCEV *X = ST->getOperand(); |
1635 | ConstantRange CR = getUnsignedRange(X); |
1636 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); |
1637 | unsigned NewBits = getTypeSizeInBits(Ty); |
1638 | if (CR.truncate(TruncBits).zeroExtend(NewBits).contains( |
1639 | CR.zextOrTrunc(NewBits))) |
1640 | return getTruncateOrZeroExtend(X, Ty); |
1641 | } |
1642 | |
1643 | // If the input value is a chrec scev, and we can prove that the value |
1644 | // did not overflow the old, smaller, value, we can zero extend all of the |
1645 | // operands (often constants). This allows analysis of something like |
1646 | // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; } |
1647 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) |
1648 | if (AR->isAffine()) { |
1649 | const SCEV *Start = AR->getStart(); |
1650 | const SCEV *Step = AR->getStepRecurrence(*this); |
1651 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
1652 | const Loop *L = AR->getLoop(); |
1653 | |
1654 | if (!AR->hasNoUnsignedWrap()) { |
1655 | auto NewFlags = proveNoWrapViaConstantRanges(AR); |
1656 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags); |
1657 | } |
1658 | |
1659 | // If we have special knowledge that this addrec won't overflow, |
1660 | // we don't need to do any further analysis. |
1661 | if (AR->hasNoUnsignedWrap()) |
1662 | return getAddRecExpr( |
1663 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1), |
1664 | getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
1665 | |
1666 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
1667 | // Note that this serves two purposes: It filters out loops that are |
1668 | // simply not analyzable, and it covers the case where this code is |
1669 | // being called from within backedge-taken count analysis, such that |
1670 | // attempting to ask for the backedge-taken count would likely result |
1671 | // in infinite recursion. In the later case, the analysis code will |
1672 | // cope with a conservative value, and it will take care to purge |
1673 | // that value once it has finished. |
1674 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(L); |
1675 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { |
1676 | // Manually compute the final value for AR, checking for |
1677 | // overflow. |
1678 | |
1679 | // Check whether the backedge-taken count can be losslessly casted to |
1680 | // the addrec's type. The count is always unsigned. |
1681 | const SCEV *CastedMaxBECount = |
1682 | getTruncateOrZeroExtend(MaxBECount, Start->getType()); |
1683 | const SCEV *RecastedMaxBECount = |
1684 | getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType()); |
1685 | if (MaxBECount == RecastedMaxBECount) { |
1686 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); |
1687 | // Check whether Start+Step*MaxBECount has no unsigned overflow. |
1688 | const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step, |
1689 | SCEV::FlagAnyWrap, Depth + 1); |
1690 | const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul, |
1691 | SCEV::FlagAnyWrap, |
1692 | Depth + 1), |
1693 | WideTy, Depth + 1); |
1694 | const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1); |
1695 | const SCEV *WideMaxBECount = |
1696 | getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1); |
1697 | const SCEV *OperandExtendedAdd = |
1698 | getAddExpr(WideStart, |
1699 | getMulExpr(WideMaxBECount, |
1700 | getZeroExtendExpr(Step, WideTy, Depth + 1), |
1701 | SCEV::FlagAnyWrap, Depth + 1), |
1702 | SCEV::FlagAnyWrap, Depth + 1); |
1703 | if (ZAdd == OperandExtendedAdd) { |
1704 | // Cache knowledge of AR NUW, which is propagated to this AddRec. |
1705 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); |
1706 | // Return the expression with the addrec on the outside. |
1707 | return getAddRecExpr( |
1708 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
1709 | Depth + 1), |
1710 | getZeroExtendExpr(Step, Ty, Depth + 1), L, |
1711 | AR->getNoWrapFlags()); |
1712 | } |
1713 | // Similar to above, only this time treat the step value as signed. |
1714 | // This covers loops that count down. |
1715 | OperandExtendedAdd = |
1716 | getAddExpr(WideStart, |
1717 | getMulExpr(WideMaxBECount, |
1718 | getSignExtendExpr(Step, WideTy, Depth + 1), |
1719 | SCEV::FlagAnyWrap, Depth + 1), |
1720 | SCEV::FlagAnyWrap, Depth + 1); |
1721 | if (ZAdd == OperandExtendedAdd) { |
1722 | // Cache knowledge of AR NW, which is propagated to this AddRec. |
1723 | // Negative step causes unsigned wrap, but it still can't self-wrap. |
1724 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); |
1725 | // Return the expression with the addrec on the outside. |
1726 | return getAddRecExpr( |
1727 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
1728 | Depth + 1), |
1729 | getSignExtendExpr(Step, Ty, Depth + 1), L, |
1730 | AR->getNoWrapFlags()); |
1731 | } |
1732 | } |
1733 | } |
1734 | |
1735 | // Normally, in the cases we can prove no-overflow via a |
1736 | // backedge guarding condition, we can also compute a backedge |
1737 | // taken count for the loop. The exceptions are assumptions and |
1738 | // guards present in the loop -- SCEV is not great at exploiting |
1739 | // these to compute max backedge taken counts, but can still use |
1740 | // these to prove lack of overflow. Use this fact to avoid |
1741 | // doing extra work that may not pay off. |
1742 | if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards || |
1743 | !AC.assumptions().empty()) { |
1744 | // If the backedge is guarded by a comparison with the pre-inc |
1745 | // value the addrec is safe. Also, if the entry is guarded by |
1746 | // a comparison with the start value and the backedge is |
1747 | // guarded by a comparison with the post-inc value, the addrec |
1748 | // is safe. |
1749 | if (isKnownPositive(Step)) { |
1750 | const SCEV *N = getConstant(APInt::getMinValue(BitWidth) - |
1751 | getUnsignedRangeMax(Step)); |
1752 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) || |
1753 | isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) { |
1754 | // Cache knowledge of AR NUW, which is propagated to this |
1755 | // AddRec. |
1756 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); |
1757 | // Return the expression with the addrec on the outside. |
1758 | return getAddRecExpr( |
1759 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
1760 | Depth + 1), |
1761 | getZeroExtendExpr(Step, Ty, Depth + 1), L, |
1762 | AR->getNoWrapFlags()); |
1763 | } |
1764 | } else if (isKnownNegative(Step)) { |
1765 | const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) - |
1766 | getSignedRangeMin(Step)); |
1767 | if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) || |
1768 | isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) { |
1769 | // Cache knowledge of AR NW, which is propagated to this |
1770 | // AddRec. Negative step causes unsigned wrap, but it |
1771 | // still can't self-wrap. |
1772 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); |
1773 | // Return the expression with the addrec on the outside. |
1774 | return getAddRecExpr( |
1775 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, |
1776 | Depth + 1), |
1777 | getSignExtendExpr(Step, Ty, Depth + 1), L, |
1778 | AR->getNoWrapFlags()); |
1779 | } |
1780 | } |
1781 | } |
1782 | |
1783 | // zext({C,+,Step}) --> (zext(D) + zext({C-D,+,Step}))<nuw><nsw> |
1784 | // if D + (C - D + Step * n) could be proven to not unsigned wrap |
1785 | // where D maximizes the number of trailing zeros of (C - D + Step * n) |
1786 | if (const auto *SC = dyn_cast<SCEVConstant>(Start)) { |
1787 | const APInt &C = SC->getAPInt(); |
1788 | const APInt &D = extractConstantWithoutWrapping(*this, C, Step); |
1789 | if (D != 0) { |
1790 | const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth); |
1791 | const SCEV *SResidual = |
1792 | getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags()); |
1793 | const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1); |
1794 | return getAddExpr(SZExtD, SZExtR, |
1795 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
1796 | Depth + 1); |
1797 | } |
1798 | } |
1799 | |
1800 | if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) { |
1801 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW); |
1802 | return getAddRecExpr( |
1803 | getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1), |
1804 | getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
1805 | } |
1806 | } |
1807 | |
1808 | // zext(A % B) --> zext(A) % zext(B) |
1809 | { |
1810 | const SCEV *LHS; |
1811 | const SCEV *RHS; |
1812 | if (matchURem(Op, LHS, RHS)) |
1813 | return getURemExpr(getZeroExtendExpr(LHS, Ty, Depth + 1), |
1814 | getZeroExtendExpr(RHS, Ty, Depth + 1)); |
1815 | } |
1816 | |
1817 | // zext(A / B) --> zext(A) / zext(B). |
1818 | if (auto *Div = dyn_cast<SCEVUDivExpr>(Op)) |
1819 | return getUDivExpr(getZeroExtendExpr(Div->getLHS(), Ty, Depth + 1), |
1820 | getZeroExtendExpr(Div->getRHS(), Ty, Depth + 1)); |
1821 | |
1822 | if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { |
1823 | // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw> |
1824 | if (SA->hasNoUnsignedWrap()) { |
1825 | // If the addition does not unsign overflow then we can, by definition, |
1826 | // commute the zero extension with the addition operation. |
1827 | SmallVector<const SCEV *, 4> Ops; |
1828 | for (const auto *Op : SA->operands()) |
1829 | Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1)); |
1830 | return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1); |
1831 | } |
1832 | |
1833 | // zext(C + x + y + ...) --> (zext(D) + zext((C - D) + x + y + ...)) |
1834 | // if D + (C - D + x + y + ...) could be proven to not unsigned wrap |
1835 | // where D maximizes the number of trailing zeros of (C - D + x + y + ...) |
1836 | // |
1837 | // Often address arithmetics contain expressions like |
1838 | // (zext (add (shl X, C1), C2)), for instance, (zext (5 + (4 * X))). |
1839 | // This transformation is useful while proving that such expressions are |
1840 | // equal or differ by a small constant amount, see LoadStoreVectorizer pass. |
1841 | if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) { |
1842 | const APInt &D = extractConstantWithoutWrapping(*this, SC, SA); |
1843 | if (D != 0) { |
1844 | const SCEV *SZExtD = getZeroExtendExpr(getConstant(D), Ty, Depth); |
1845 | const SCEV *SResidual = |
1846 | getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth); |
1847 | const SCEV *SZExtR = getZeroExtendExpr(SResidual, Ty, Depth + 1); |
1848 | return getAddExpr(SZExtD, SZExtR, |
1849 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
1850 | Depth + 1); |
1851 | } |
1852 | } |
1853 | } |
1854 | |
1855 | if (auto *SM = dyn_cast<SCEVMulExpr>(Op)) { |
1856 | // zext((A * B * ...)<nuw>) --> (zext(A) * zext(B) * ...)<nuw> |
1857 | if (SM->hasNoUnsignedWrap()) { |
1858 | // If the multiply does not unsign overflow then we can, by definition, |
1859 | // commute the zero extension with the multiply operation. |
1860 | SmallVector<const SCEV *, 4> Ops; |
1861 | for (const auto *Op : SM->operands()) |
1862 | Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1)); |
1863 | return getMulExpr(Ops, SCEV::FlagNUW, Depth + 1); |
1864 | } |
1865 | |
1866 | // zext(2^K * (trunc X to iN)) to iM -> |
1867 | // 2^K * (zext(trunc X to i{N-K}) to iM)<nuw> |
1868 | // |
1869 | // Proof: |
1870 | // |
1871 | // zext(2^K * (trunc X to iN)) to iM |
1872 | // = zext((trunc X to iN) << K) to iM |
1873 | // = zext((trunc X to i{N-K}) << K)<nuw> to iM |
1874 | // (because shl removes the top K bits) |
1875 | // = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM |
1876 | // = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>. |
1877 | // |
1878 | if (SM->getNumOperands() == 2) |
1879 | if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0))) |
1880 | if (MulLHS->getAPInt().isPowerOf2()) |
1881 | if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) { |
1882 | int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) - |
1883 | MulLHS->getAPInt().logBase2(); |
1884 | Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits); |
1885 | return getMulExpr( |
1886 | getZeroExtendExpr(MulLHS, Ty), |
1887 | getZeroExtendExpr( |
1888 | getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty), |
1889 | SCEV::FlagNUW, Depth + 1); |
1890 | } |
1891 | } |
1892 | |
1893 | // The cast wasn't folded; create an explicit cast node. |
1894 | // Recompute the insert position, as it may have been invalidated. |
1895 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
1896 | SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator), |
1897 | Op, Ty); |
1898 | UniqueSCEVs.InsertNode(S, IP); |
1899 | addToLoopUseLists(S); |
1900 | return S; |
1901 | } |
1902 | |
1903 | const SCEV * |
1904 | ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) { |
1905 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1906, __PRETTY_FUNCTION__)) |
1906 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1906, __PRETTY_FUNCTION__)); |
1907 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1908, __PRETTY_FUNCTION__)) |
1908 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 1908, __PRETTY_FUNCTION__)); |
1909 | Ty = getEffectiveSCEVType(Ty); |
1910 | |
1911 | // Fold if the operand is constant. |
1912 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
1913 | return getConstant( |
1914 | cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty))); |
1915 | |
1916 | // sext(sext(x)) --> sext(x) |
1917 | if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op)) |
1918 | return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1); |
1919 | |
1920 | // sext(zext(x)) --> zext(x) |
1921 | if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op)) |
1922 | return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1); |
1923 | |
1924 | // Before doing any expensive analysis, check to see if we've already |
1925 | // computed a SCEV for this Op and Ty. |
1926 | FoldingSetNodeID ID; |
1927 | ID.AddInteger(scSignExtend); |
1928 | ID.AddPointer(Op); |
1929 | ID.AddPointer(Ty); |
1930 | void *IP = nullptr; |
1931 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
1932 | // Limit recursion depth. |
1933 | if (Depth > MaxExtDepth) { |
1934 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), |
1935 | Op, Ty); |
1936 | UniqueSCEVs.InsertNode(S, IP); |
1937 | addToLoopUseLists(S); |
1938 | return S; |
1939 | } |
1940 | |
1941 | // sext(trunc(x)) --> sext(x) or x or trunc(x) |
1942 | if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) { |
1943 | // It's possible the bits taken off by the truncate were all sign bits. If |
1944 | // so, we should be able to simplify this further. |
1945 | const SCEV *X = ST->getOperand(); |
1946 | ConstantRange CR = getSignedRange(X); |
1947 | unsigned TruncBits = getTypeSizeInBits(ST->getType()); |
1948 | unsigned NewBits = getTypeSizeInBits(Ty); |
1949 | if (CR.truncate(TruncBits).signExtend(NewBits).contains( |
1950 | CR.sextOrTrunc(NewBits))) |
1951 | return getTruncateOrSignExtend(X, Ty); |
1952 | } |
1953 | |
1954 | if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) { |
1955 | // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw> |
1956 | if (SA->hasNoSignedWrap()) { |
1957 | // If the addition does not sign overflow then we can, by definition, |
1958 | // commute the sign extension with the addition operation. |
1959 | SmallVector<const SCEV *, 4> Ops; |
1960 | for (const auto *Op : SA->operands()) |
1961 | Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1)); |
1962 | return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1); |
1963 | } |
1964 | |
1965 | // sext(C + x + y + ...) --> (sext(D) + sext((C - D) + x + y + ...)) |
1966 | // if D + (C - D + x + y + ...) could be proven to not signed wrap |
1967 | // where D maximizes the number of trailing zeros of (C - D + x + y + ...) |
1968 | // |
1969 | // For instance, this will bring two seemingly different expressions: |
1970 | // 1 + sext(5 + 20 * %x + 24 * %y) and |
1971 | // sext(6 + 20 * %x + 24 * %y) |
1972 | // to the same form: |
1973 | // 2 + sext(4 + 20 * %x + 24 * %y) |
1974 | if (const auto *SC = dyn_cast<SCEVConstant>(SA->getOperand(0))) { |
1975 | const APInt &D = extractConstantWithoutWrapping(*this, SC, SA); |
1976 | if (D != 0) { |
1977 | const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth); |
1978 | const SCEV *SResidual = |
1979 | getAddExpr(getConstant(-D), SA, SCEV::FlagAnyWrap, Depth); |
1980 | const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1); |
1981 | return getAddExpr(SSExtD, SSExtR, |
1982 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
1983 | Depth + 1); |
1984 | } |
1985 | } |
1986 | } |
1987 | // If the input value is a chrec scev, and we can prove that the value |
1988 | // did not overflow the old, smaller, value, we can sign extend all of the |
1989 | // operands (often constants). This allows analysis of something like |
1990 | // this: for (signed char X = 0; X < 100; ++X) { int Y = X; } |
1991 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) |
1992 | if (AR->isAffine()) { |
1993 | const SCEV *Start = AR->getStart(); |
1994 | const SCEV *Step = AR->getStepRecurrence(*this); |
1995 | unsigned BitWidth = getTypeSizeInBits(AR->getType()); |
1996 | const Loop *L = AR->getLoop(); |
1997 | |
1998 | if (!AR->hasNoSignedWrap()) { |
1999 | auto NewFlags = proveNoWrapViaConstantRanges(AR); |
2000 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags); |
2001 | } |
2002 | |
2003 | // If we have special knowledge that this addrec won't overflow, |
2004 | // we don't need to do any further analysis. |
2005 | if (AR->hasNoSignedWrap()) |
2006 | return getAddRecExpr( |
2007 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), |
2008 | getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW); |
2009 | |
2010 | // Check whether the backedge-taken count is SCEVCouldNotCompute. |
2011 | // Note that this serves two purposes: It filters out loops that are |
2012 | // simply not analyzable, and it covers the case where this code is |
2013 | // being called from within backedge-taken count analysis, such that |
2014 | // attempting to ask for the backedge-taken count would likely result |
2015 | // in infinite recursion. In the later case, the analysis code will |
2016 | // cope with a conservative value, and it will take care to purge |
2017 | // that value once it has finished. |
2018 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(L); |
2019 | if (!isa<SCEVCouldNotCompute>(MaxBECount)) { |
2020 | // Manually compute the final value for AR, checking for |
2021 | // overflow. |
2022 | |
2023 | // Check whether the backedge-taken count can be losslessly casted to |
2024 | // the addrec's type. The count is always unsigned. |
2025 | const SCEV *CastedMaxBECount = |
2026 | getTruncateOrZeroExtend(MaxBECount, Start->getType()); |
2027 | const SCEV *RecastedMaxBECount = |
2028 | getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType()); |
2029 | if (MaxBECount == RecastedMaxBECount) { |
2030 | Type *WideTy = IntegerType::get(getContext(), BitWidth * 2); |
2031 | // Check whether Start+Step*MaxBECount has no signed overflow. |
2032 | const SCEV *SMul = getMulExpr(CastedMaxBECount, Step, |
2033 | SCEV::FlagAnyWrap, Depth + 1); |
2034 | const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul, |
2035 | SCEV::FlagAnyWrap, |
2036 | Depth + 1), |
2037 | WideTy, Depth + 1); |
2038 | const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1); |
2039 | const SCEV *WideMaxBECount = |
2040 | getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1); |
2041 | const SCEV *OperandExtendedAdd = |
2042 | getAddExpr(WideStart, |
2043 | getMulExpr(WideMaxBECount, |
2044 | getSignExtendExpr(Step, WideTy, Depth + 1), |
2045 | SCEV::FlagAnyWrap, Depth + 1), |
2046 | SCEV::FlagAnyWrap, Depth + 1); |
2047 | if (SAdd == OperandExtendedAdd) { |
2048 | // Cache knowledge of AR NSW, which is propagated to this AddRec. |
2049 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); |
2050 | // Return the expression with the addrec on the outside. |
2051 | return getAddRecExpr( |
2052 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, |
2053 | Depth + 1), |
2054 | getSignExtendExpr(Step, Ty, Depth + 1), L, |
2055 | AR->getNoWrapFlags()); |
2056 | } |
2057 | // Similar to above, only this time treat the step value as unsigned. |
2058 | // This covers loops that count up with an unsigned step. |
2059 | OperandExtendedAdd = |
2060 | getAddExpr(WideStart, |
2061 | getMulExpr(WideMaxBECount, |
2062 | getZeroExtendExpr(Step, WideTy, Depth + 1), |
2063 | SCEV::FlagAnyWrap, Depth + 1), |
2064 | SCEV::FlagAnyWrap, Depth + 1); |
2065 | if (SAdd == OperandExtendedAdd) { |
2066 | // If AR wraps around then |
2067 | // |
2068 | // abs(Step) * MaxBECount > unsigned-max(AR->getType()) |
2069 | // => SAdd != OperandExtendedAdd |
2070 | // |
2071 | // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=> |
2072 | // (SAdd == OperandExtendedAdd => AR is NW) |
2073 | |
2074 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW); |
2075 | |
2076 | // Return the expression with the addrec on the outside. |
2077 | return getAddRecExpr( |
2078 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, |
2079 | Depth + 1), |
2080 | getZeroExtendExpr(Step, Ty, Depth + 1), L, |
2081 | AR->getNoWrapFlags()); |
2082 | } |
2083 | } |
2084 | } |
2085 | |
2086 | // Normally, in the cases we can prove no-overflow via a |
2087 | // backedge guarding condition, we can also compute a backedge |
2088 | // taken count for the loop. The exceptions are assumptions and |
2089 | // guards present in the loop -- SCEV is not great at exploiting |
2090 | // these to compute max backedge taken counts, but can still use |
2091 | // these to prove lack of overflow. Use this fact to avoid |
2092 | // doing extra work that may not pay off. |
2093 | |
2094 | if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards || |
2095 | !AC.assumptions().empty()) { |
2096 | // If the backedge is guarded by a comparison with the pre-inc |
2097 | // value the addrec is safe. Also, if the entry is guarded by |
2098 | // a comparison with the start value and the backedge is |
2099 | // guarded by a comparison with the post-inc value, the addrec |
2100 | // is safe. |
2101 | ICmpInst::Predicate Pred; |
2102 | const SCEV *OverflowLimit = |
2103 | getSignedOverflowLimitForStep(Step, &Pred, this); |
2104 | if (OverflowLimit && |
2105 | (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) || |
2106 | isKnownOnEveryIteration(Pred, AR, OverflowLimit))) { |
2107 | // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec. |
2108 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); |
2109 | return getAddRecExpr( |
2110 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), |
2111 | getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
2112 | } |
2113 | } |
2114 | |
2115 | // sext({C,+,Step}) --> (sext(D) + sext({C-D,+,Step}))<nuw><nsw> |
2116 | // if D + (C - D + Step * n) could be proven to not signed wrap |
2117 | // where D maximizes the number of trailing zeros of (C - D + Step * n) |
2118 | if (const auto *SC = dyn_cast<SCEVConstant>(Start)) { |
2119 | const APInt &C = SC->getAPInt(); |
2120 | const APInt &D = extractConstantWithoutWrapping(*this, C, Step); |
2121 | if (D != 0) { |
2122 | const SCEV *SSExtD = getSignExtendExpr(getConstant(D), Ty, Depth); |
2123 | const SCEV *SResidual = |
2124 | getAddRecExpr(getConstant(C - D), Step, L, AR->getNoWrapFlags()); |
2125 | const SCEV *SSExtR = getSignExtendExpr(SResidual, Ty, Depth + 1); |
2126 | return getAddExpr(SSExtD, SSExtR, |
2127 | (SCEV::NoWrapFlags)(SCEV::FlagNSW | SCEV::FlagNUW), |
2128 | Depth + 1); |
2129 | } |
2130 | } |
2131 | |
2132 | if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) { |
2133 | const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW); |
2134 | return getAddRecExpr( |
2135 | getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1), |
2136 | getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags()); |
2137 | } |
2138 | } |
2139 | |
2140 | // If the input value is provably positive and we could not simplify |
2141 | // away the sext build a zext instead. |
2142 | if (isKnownNonNegative(Op)) |
2143 | return getZeroExtendExpr(Op, Ty, Depth + 1); |
2144 | |
2145 | // The cast wasn't folded; create an explicit cast node. |
2146 | // Recompute the insert position, as it may have been invalidated. |
2147 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
2148 | SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator), |
2149 | Op, Ty); |
2150 | UniqueSCEVs.InsertNode(S, IP); |
2151 | addToLoopUseLists(S); |
2152 | return S; |
2153 | } |
2154 | |
2155 | /// getAnyExtendExpr - Return a SCEV for the given operand extended with |
2156 | /// unspecified bits out to the given type. |
2157 | const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op, |
2158 | Type *Ty) { |
2159 | assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2160, __PRETTY_FUNCTION__)) |
2160 | "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits( Ty) && "This is not an extending conversion!") ? static_cast <void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2160, __PRETTY_FUNCTION__)); |
2161 | assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2162, __PRETTY_FUNCTION__)) |
2162 | "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2162, __PRETTY_FUNCTION__)); |
2163 | Ty = getEffectiveSCEVType(Ty); |
2164 | |
2165 | // Sign-extend negative constants. |
2166 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op)) |
2167 | if (SC->getAPInt().isNegative()) |
2168 | return getSignExtendExpr(Op, Ty); |
2169 | |
2170 | // Peel off a truncate cast. |
2171 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) { |
2172 | const SCEV *NewOp = T->getOperand(); |
2173 | if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty)) |
2174 | return getAnyExtendExpr(NewOp, Ty); |
2175 | return getTruncateOrNoop(NewOp, Ty); |
2176 | } |
2177 | |
2178 | // Next try a zext cast. If the cast is folded, use it. |
2179 | const SCEV *ZExt = getZeroExtendExpr(Op, Ty); |
2180 | if (!isa<SCEVZeroExtendExpr>(ZExt)) |
2181 | return ZExt; |
2182 | |
2183 | // Next try a sext cast. If the cast is folded, use it. |
2184 | const SCEV *SExt = getSignExtendExpr(Op, Ty); |
2185 | if (!isa<SCEVSignExtendExpr>(SExt)) |
2186 | return SExt; |
2187 | |
2188 | // Force the cast to be folded into the operands of an addrec. |
2189 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) { |
2190 | SmallVector<const SCEV *, 4> Ops; |
2191 | for (const SCEV *Op : AR->operands()) |
2192 | Ops.push_back(getAnyExtendExpr(Op, Ty)); |
2193 | return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW); |
2194 | } |
2195 | |
2196 | // If the expression is obviously signed, use the sext cast value. |
2197 | if (isa<SCEVSMaxExpr>(Op)) |
2198 | return SExt; |
2199 | |
2200 | // Absent any other information, use the zext cast value. |
2201 | return ZExt; |
2202 | } |
2203 | |
2204 | /// Process the given Ops list, which is a list of operands to be added under |
2205 | /// the given scale, update the given map. This is a helper function for |
2206 | /// getAddRecExpr. As an example of what it does, given a sequence of operands |
2207 | /// that would form an add expression like this: |
2208 | /// |
2209 | /// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r) |
2210 | /// |
2211 | /// where A and B are constants, update the map with these values: |
2212 | /// |
2213 | /// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0) |
2214 | /// |
2215 | /// and add 13 + A*B*29 to AccumulatedConstant. |
2216 | /// This will allow getAddRecExpr to produce this: |
2217 | /// |
2218 | /// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B) |
2219 | /// |
2220 | /// This form often exposes folding opportunities that are hidden in |
2221 | /// the original operand list. |
2222 | /// |
2223 | /// Return true iff it appears that any interesting folding opportunities |
2224 | /// may be exposed. This helps getAddRecExpr short-circuit extra work in |
2225 | /// the common case where no interesting opportunities are present, and |
2226 | /// is also used as a check to avoid infinite recursion. |
2227 | static bool |
2228 | CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M, |
2229 | SmallVectorImpl<const SCEV *> &NewOps, |
2230 | APInt &AccumulatedConstant, |
2231 | const SCEV *const *Ops, size_t NumOperands, |
2232 | const APInt &Scale, |
2233 | ScalarEvolution &SE) { |
2234 | bool Interesting = false; |
2235 | |
2236 | // Iterate over the add operands. They are sorted, with constants first. |
2237 | unsigned i = 0; |
2238 | while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { |
2239 | ++i; |
2240 | // Pull a buried constant out to the outside. |
2241 | if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero()) |
2242 | Interesting = true; |
2243 | AccumulatedConstant += Scale * C->getAPInt(); |
2244 | } |
2245 | |
2246 | // Next comes everything else. We're especially interested in multiplies |
2247 | // here, but they're in the middle, so just visit the rest with one loop. |
2248 | for (; i != NumOperands; ++i) { |
2249 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]); |
2250 | if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) { |
2251 | APInt NewScale = |
2252 | Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt(); |
2253 | if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) { |
2254 | // A multiplication of a constant with another add; recurse. |
2255 | const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1)); |
2256 | Interesting |= |
2257 | CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, |
2258 | Add->op_begin(), Add->getNumOperands(), |
2259 | NewScale, SE); |
2260 | } else { |
2261 | // A multiplication of a constant with some other value. Update |
2262 | // the map. |
2263 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end()); |
2264 | const SCEV *Key = SE.getMulExpr(MulOps); |
2265 | auto Pair = M.insert({Key, NewScale}); |
2266 | if (Pair.second) { |
2267 | NewOps.push_back(Pair.first->first); |
2268 | } else { |
2269 | Pair.first->second += NewScale; |
2270 | // The map already had an entry for this value, which may indicate |
2271 | // a folding opportunity. |
2272 | Interesting = true; |
2273 | } |
2274 | } |
2275 | } else { |
2276 | // An ordinary operand. Update the map. |
2277 | std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair = |
2278 | M.insert({Ops[i], Scale}); |
2279 | if (Pair.second) { |
2280 | NewOps.push_back(Pair.first->first); |
2281 | } else { |
2282 | Pair.first->second += Scale; |
2283 | // The map already had an entry for this value, which may indicate |
2284 | // a folding opportunity. |
2285 | Interesting = true; |
2286 | } |
2287 | } |
2288 | } |
2289 | |
2290 | return Interesting; |
2291 | } |
2292 | |
2293 | // We're trying to construct a SCEV of type `Type' with `Ops' as operands and |
2294 | // `OldFlags' as can't-wrap behavior. Infer a more aggressive set of |
2295 | // can't-overflow flags for the operation if possible. |
2296 | static SCEV::NoWrapFlags |
2297 | StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type, |
2298 | const SmallVectorImpl<const SCEV *> &Ops, |
2299 | SCEV::NoWrapFlags Flags) { |
2300 | using namespace std::placeholders; |
2301 | |
2302 | using OBO = OverflowingBinaryOperator; |
2303 | |
2304 | bool CanAnalyze = |
2305 | Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr; |
2306 | (void)CanAnalyze; |
2307 | assert(CanAnalyze && "don't call from other places!")((CanAnalyze && "don't call from other places!") ? static_cast <void> (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2307, __PRETTY_FUNCTION__)); |
2308 | |
2309 | int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW; |
2310 | SCEV::NoWrapFlags SignOrUnsignWrap = |
2311 | ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); |
2312 | |
2313 | // If FlagNSW is true and all the operands are non-negative, infer FlagNUW. |
2314 | auto IsKnownNonNegative = [&](const SCEV *S) { |
2315 | return SE->isKnownNonNegative(S); |
2316 | }; |
2317 | |
2318 | if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative)) |
2319 | Flags = |
2320 | ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask); |
2321 | |
2322 | SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask); |
2323 | |
2324 | if (SignOrUnsignWrap != SignOrUnsignMask && |
2325 | (Type == scAddExpr || Type == scMulExpr) && Ops.size() == 2 && |
2326 | isa<SCEVConstant>(Ops[0])) { |
2327 | |
2328 | auto Opcode = [&] { |
2329 | switch (Type) { |
2330 | case scAddExpr: |
2331 | return Instruction::Add; |
2332 | case scMulExpr: |
2333 | return Instruction::Mul; |
2334 | default: |
2335 | llvm_unreachable("Unexpected SCEV op.")::llvm::llvm_unreachable_internal("Unexpected SCEV op.", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2335); |
2336 | } |
2337 | }(); |
2338 | |
2339 | const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt(); |
2340 | |
2341 | // (A <opcode> C) --> (A <opcode> C)<nsw> if the op doesn't sign overflow. |
2342 | if (!(SignOrUnsignWrap & SCEV::FlagNSW)) { |
2343 | auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
2344 | Opcode, C, OBO::NoSignedWrap); |
2345 | if (NSWRegion.contains(SE->getSignedRange(Ops[1]))) |
2346 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); |
2347 | } |
2348 | |
2349 | // (A <opcode> C) --> (A <opcode> C)<nuw> if the op doesn't unsign overflow. |
2350 | if (!(SignOrUnsignWrap & SCEV::FlagNUW)) { |
2351 | auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
2352 | Opcode, C, OBO::NoUnsignedWrap); |
2353 | if (NUWRegion.contains(SE->getUnsignedRange(Ops[1]))) |
2354 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); |
2355 | } |
2356 | } |
2357 | |
2358 | return Flags; |
2359 | } |
2360 | |
2361 | bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) { |
2362 | return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader()); |
2363 | } |
2364 | |
2365 | /// Get a canonical add expression, or something simpler if possible. |
2366 | const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops, |
2367 | SCEV::NoWrapFlags Flags, |
2368 | unsigned Depth) { |
2369 | assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed" ) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2370, __PRETTY_FUNCTION__)) |
2370 | "only nuw or nsw allowed")((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed" ) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2370, __PRETTY_FUNCTION__)); |
2371 | assert(!Ops.empty() && "Cannot get empty add!")((!Ops.empty() && "Cannot get empty add!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2371, __PRETTY_FUNCTION__)); |
2372 | if (Ops.size() == 1) return Ops[0]; |
2373 | #ifndef NDEBUG |
2374 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
2375 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
2376 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVAddExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2377, __PRETTY_FUNCTION__)) |
2377 | "SCEVAddExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVAddExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2377, __PRETTY_FUNCTION__)); |
2378 | #endif |
2379 | |
2380 | // Sort by complexity, this groups all similar expression types together. |
2381 | GroupByComplexity(Ops, &LI, DT); |
2382 | |
2383 | Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags); |
2384 | |
2385 | // If there are any constants, fold them together. |
2386 | unsigned Idx = 0; |
2387 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
2388 | ++Idx; |
2389 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2389, __PRETTY_FUNCTION__)); |
2390 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
2391 | // We found two constants, fold them together! |
2392 | Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt()); |
2393 | if (Ops.size() == 2) return Ops[0]; |
2394 | Ops.erase(Ops.begin()+1); // Erase the folded element |
2395 | LHSC = cast<SCEVConstant>(Ops[0]); |
2396 | } |
2397 | |
2398 | // If we are left with a constant zero being added, strip it off. |
2399 | if (LHSC->getValue()->isZero()) { |
2400 | Ops.erase(Ops.begin()); |
2401 | --Idx; |
2402 | } |
2403 | |
2404 | if (Ops.size() == 1) return Ops[0]; |
2405 | } |
2406 | |
2407 | // Limit recursion calls depth. |
2408 | if (Depth > MaxArithDepth) |
2409 | return getOrCreateAddExpr(Ops, Flags); |
2410 | |
2411 | // Okay, check to see if the same value occurs in the operand list more than |
2412 | // once. If so, merge them together into an multiply expression. Since we |
2413 | // sorted the list, these values are required to be adjacent. |
2414 | Type *Ty = Ops[0]->getType(); |
2415 | bool FoundMatch = false; |
2416 | for (unsigned i = 0, e = Ops.size(); i != e-1; ++i) |
2417 | if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2 |
2418 | // Scan ahead to count how many equal operands there are. |
2419 | unsigned Count = 2; |
2420 | while (i+Count != e && Ops[i+Count] == Ops[i]) |
2421 | ++Count; |
2422 | // Merge the values into a multiply. |
2423 | const SCEV *Scale = getConstant(Ty, Count); |
2424 | const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1); |
2425 | if (Ops.size() == Count) |
2426 | return Mul; |
2427 | Ops[i] = Mul; |
2428 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count); |
2429 | --i; e -= Count - 1; |
2430 | FoundMatch = true; |
2431 | } |
2432 | if (FoundMatch) |
2433 | return getAddExpr(Ops, Flags, Depth + 1); |
2434 | |
2435 | // Check for truncates. If all the operands are truncated from the same |
2436 | // type, see if factoring out the truncate would permit the result to be |
2437 | // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y) |
2438 | // if the contents of the resulting outer trunc fold to something simple. |
2439 | auto FindTruncSrcType = [&]() -> Type * { |
2440 | // We're ultimately looking to fold an addrec of truncs and muls of only |
2441 | // constants and truncs, so if we find any other types of SCEV |
2442 | // as operands of the addrec then we bail and return nullptr here. |
2443 | // Otherwise, we return the type of the operand of a trunc that we find. |
2444 | if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx])) |
2445 | return T->getOperand()->getType(); |
2446 | if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { |
2447 | const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1); |
2448 | if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp)) |
2449 | return T->getOperand()->getType(); |
2450 | } |
2451 | return nullptr; |
2452 | }; |
2453 | if (auto *SrcType = FindTruncSrcType()) { |
2454 | SmallVector<const SCEV *, 8> LargeOps; |
2455 | bool Ok = true; |
2456 | // Check all the operands to see if they can be represented in the |
2457 | // source type of the truncate. |
2458 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
2459 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) { |
2460 | if (T->getOperand()->getType() != SrcType) { |
2461 | Ok = false; |
2462 | break; |
2463 | } |
2464 | LargeOps.push_back(T->getOperand()); |
2465 | } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) { |
2466 | LargeOps.push_back(getAnyExtendExpr(C, SrcType)); |
2467 | } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) { |
2468 | SmallVector<const SCEV *, 8> LargeMulOps; |
2469 | for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) { |
2470 | if (const SCEVTruncateExpr *T = |
2471 | dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) { |
2472 | if (T->getOperand()->getType() != SrcType) { |
2473 | Ok = false; |
2474 | break; |
2475 | } |
2476 | LargeMulOps.push_back(T->getOperand()); |
2477 | } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) { |
2478 | LargeMulOps.push_back(getAnyExtendExpr(C, SrcType)); |
2479 | } else { |
2480 | Ok = false; |
2481 | break; |
2482 | } |
2483 | } |
2484 | if (Ok) |
2485 | LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1)); |
2486 | } else { |
2487 | Ok = false; |
2488 | break; |
2489 | } |
2490 | } |
2491 | if (Ok) { |
2492 | // Evaluate the expression in the larger type. |
2493 | const SCEV *Fold = getAddExpr(LargeOps, SCEV::FlagAnyWrap, Depth + 1); |
2494 | // If it folds to something simple, use it. Otherwise, don't. |
2495 | if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold)) |
2496 | return getTruncateExpr(Fold, Ty); |
2497 | } |
2498 | } |
2499 | |
2500 | // Skip past any other cast SCEVs. |
2501 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr) |
2502 | ++Idx; |
2503 | |
2504 | // If there are add operands they would be next. |
2505 | if (Idx < Ops.size()) { |
2506 | bool DeletedAdd = false; |
2507 | while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) { |
2508 | if (Ops.size() > AddOpsInlineThreshold || |
2509 | Add->getNumOperands() > AddOpsInlineThreshold) |
2510 | break; |
2511 | // If we have an add, expand the add operands onto the end of the operands |
2512 | // list. |
2513 | Ops.erase(Ops.begin()+Idx); |
2514 | Ops.append(Add->op_begin(), Add->op_end()); |
2515 | DeletedAdd = true; |
2516 | } |
2517 | |
2518 | // If we deleted at least one add, we added operands to the end of the list, |
2519 | // and they are not necessarily sorted. Recurse to resort and resimplify |
2520 | // any operands we just acquired. |
2521 | if (DeletedAdd) |
2522 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2523 | } |
2524 | |
2525 | // Skip over the add expression until we get to a multiply. |
2526 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) |
2527 | ++Idx; |
2528 | |
2529 | // Check to see if there are any folding opportunities present with |
2530 | // operands multiplied by constant values. |
2531 | if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) { |
2532 | uint64_t BitWidth = getTypeSizeInBits(Ty); |
2533 | DenseMap<const SCEV *, APInt> M; |
2534 | SmallVector<const SCEV *, 8> NewOps; |
2535 | APInt AccumulatedConstant(BitWidth, 0); |
2536 | if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant, |
2537 | Ops.data(), Ops.size(), |
2538 | APInt(BitWidth, 1), *this)) { |
2539 | struct APIntCompare { |
2540 | bool operator()(const APInt &LHS, const APInt &RHS) const { |
2541 | return LHS.ult(RHS); |
2542 | } |
2543 | }; |
2544 | |
2545 | // Some interesting folding opportunity is present, so its worthwhile to |
2546 | // re-generate the operands list. Group the operands by constant scale, |
2547 | // to avoid multiplying by the same constant scale multiple times. |
2548 | std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists; |
2549 | for (const SCEV *NewOp : NewOps) |
2550 | MulOpLists[M.find(NewOp)->second].push_back(NewOp); |
2551 | // Re-generate the operands list. |
2552 | Ops.clear(); |
2553 | if (AccumulatedConstant != 0) |
2554 | Ops.push_back(getConstant(AccumulatedConstant)); |
2555 | for (auto &MulOp : MulOpLists) |
2556 | if (MulOp.first != 0) |
2557 | Ops.push_back(getMulExpr( |
2558 | getConstant(MulOp.first), |
2559 | getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1), |
2560 | SCEV::FlagAnyWrap, Depth + 1)); |
2561 | if (Ops.empty()) |
2562 | return getZero(Ty); |
2563 | if (Ops.size() == 1) |
2564 | return Ops[0]; |
2565 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2566 | } |
2567 | } |
2568 | |
2569 | // If we are adding something to a multiply expression, make sure the |
2570 | // something is not already an operand of the multiply. If so, merge it into |
2571 | // the multiply. |
2572 | for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) { |
2573 | const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]); |
2574 | for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) { |
2575 | const SCEV *MulOpSCEV = Mul->getOperand(MulOp); |
2576 | if (isa<SCEVConstant>(MulOpSCEV)) |
2577 | continue; |
2578 | for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp) |
2579 | if (MulOpSCEV == Ops[AddOp]) { |
2580 | // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1)) |
2581 | const SCEV *InnerMul = Mul->getOperand(MulOp == 0); |
2582 | if (Mul->getNumOperands() != 2) { |
2583 | // If the multiply has more than two operands, we must get the |
2584 | // Y*Z term. |
2585 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), |
2586 | Mul->op_begin()+MulOp); |
2587 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); |
2588 | InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); |
2589 | } |
2590 | SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul}; |
2591 | const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); |
2592 | const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV, |
2593 | SCEV::FlagAnyWrap, Depth + 1); |
2594 | if (Ops.size() == 2) return OuterMul; |
2595 | if (AddOp < Idx) { |
2596 | Ops.erase(Ops.begin()+AddOp); |
2597 | Ops.erase(Ops.begin()+Idx-1); |
2598 | } else { |
2599 | Ops.erase(Ops.begin()+Idx); |
2600 | Ops.erase(Ops.begin()+AddOp-1); |
2601 | } |
2602 | Ops.push_back(OuterMul); |
2603 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2604 | } |
2605 | |
2606 | // Check this multiply against other multiplies being added together. |
2607 | for (unsigned OtherMulIdx = Idx+1; |
2608 | OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]); |
2609 | ++OtherMulIdx) { |
2610 | const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]); |
2611 | // If MulOp occurs in OtherMul, we can fold the two multiplies |
2612 | // together. |
2613 | for (unsigned OMulOp = 0, e = OtherMul->getNumOperands(); |
2614 | OMulOp != e; ++OMulOp) |
2615 | if (OtherMul->getOperand(OMulOp) == MulOpSCEV) { |
2616 | // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E)) |
2617 | const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0); |
2618 | if (Mul->getNumOperands() != 2) { |
2619 | SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), |
2620 | Mul->op_begin()+MulOp); |
2621 | MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end()); |
2622 | InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); |
2623 | } |
2624 | const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0); |
2625 | if (OtherMul->getNumOperands() != 2) { |
2626 | SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(), |
2627 | OtherMul->op_begin()+OMulOp); |
2628 | MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end()); |
2629 | InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1); |
2630 | } |
2631 | SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2}; |
2632 | const SCEV *InnerMulSum = |
2633 | getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); |
2634 | const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum, |
2635 | SCEV::FlagAnyWrap, Depth + 1); |
2636 | if (Ops.size() == 2) return OuterMul; |
2637 | Ops.erase(Ops.begin()+Idx); |
2638 | Ops.erase(Ops.begin()+OtherMulIdx-1); |
2639 | Ops.push_back(OuterMul); |
2640 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2641 | } |
2642 | } |
2643 | } |
2644 | } |
2645 | |
2646 | // If there are any add recurrences in the operands list, see if any other |
2647 | // added values are loop invariant. If so, we can fold them into the |
2648 | // recurrence. |
2649 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) |
2650 | ++Idx; |
2651 | |
2652 | // Scan over all recurrences, trying to fold loop invariants into them. |
2653 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { |
2654 | // Scan all of the other operands to this add and add them to the vector if |
2655 | // they are loop invariant w.r.t. the recurrence. |
2656 | SmallVector<const SCEV *, 8> LIOps; |
2657 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); |
2658 | const Loop *AddRecLoop = AddRec->getLoop(); |
2659 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
2660 | if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) { |
2661 | LIOps.push_back(Ops[i]); |
2662 | Ops.erase(Ops.begin()+i); |
2663 | --i; --e; |
2664 | } |
2665 | |
2666 | // If we found some loop invariants, fold them into the recurrence. |
2667 | if (!LIOps.empty()) { |
2668 | // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step} |
2669 | LIOps.push_back(AddRec->getStart()); |
2670 | |
2671 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(), |
2672 | AddRec->op_end()); |
2673 | // This follows from the fact that the no-wrap flags on the outer add |
2674 | // expression are applicable on the 0th iteration, when the add recurrence |
2675 | // will be equal to its start value. |
2676 | AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1); |
2677 | |
2678 | // Build the new addrec. Propagate the NUW and NSW flags if both the |
2679 | // outer add and the inner addrec are guaranteed to have no overflow. |
2680 | // Always propagate NW. |
2681 | Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW)); |
2682 | const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags); |
2683 | |
2684 | // If all of the other operands were loop invariant, we are done. |
2685 | if (Ops.size() == 1) return NewRec; |
2686 | |
2687 | // Otherwise, add the folded AddRec by the non-invariant parts. |
2688 | for (unsigned i = 0;; ++i) |
2689 | if (Ops[i] == AddRec) { |
2690 | Ops[i] = NewRec; |
2691 | break; |
2692 | } |
2693 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2694 | } |
2695 | |
2696 | // Okay, if there weren't any loop invariants to be folded, check to see if |
2697 | // there are multiple AddRec's with the same loop induction variable being |
2698 | // added together. If so, we can fold them. |
2699 | for (unsigned OtherIdx = Idx+1; |
2700 | OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
2701 | ++OtherIdx) { |
2702 | // We expect the AddRecExpr's to be sorted in reverse dominance order, |
2703 | // so that the 1st found AddRecExpr is dominated by all others. |
2704 | assert(DT.dominates(((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2707, __PRETTY_FUNCTION__)) |
2705 | cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2707, __PRETTY_FUNCTION__)) |
2706 | AddRec->getLoop()->getHeader()) &&((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2707, __PRETTY_FUNCTION__)) |
2707 | "AddRecExprs are not sorted in reverse dominance order?")((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])-> getLoop()->getHeader(), AddRec->getLoop()->getHeader ()) && "AddRecExprs are not sorted in reverse dominance order?" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2707, __PRETTY_FUNCTION__)); |
2708 | if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) { |
2709 | // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L> |
2710 | SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(), |
2711 | AddRec->op_end()); |
2712 | for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
2713 | ++OtherIdx) { |
2714 | const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]); |
2715 | if (OtherAddRec->getLoop() == AddRecLoop) { |
2716 | for (unsigned i = 0, e = OtherAddRec->getNumOperands(); |
2717 | i != e; ++i) { |
2718 | if (i >= AddRecOps.size()) { |
2719 | AddRecOps.append(OtherAddRec->op_begin()+i, |
2720 | OtherAddRec->op_end()); |
2721 | break; |
2722 | } |
2723 | SmallVector<const SCEV *, 2> TwoOps = { |
2724 | AddRecOps[i], OtherAddRec->getOperand(i)}; |
2725 | AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1); |
2726 | } |
2727 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; |
2728 | } |
2729 | } |
2730 | // Step size has changed, so we cannot guarantee no self-wraparound. |
2731 | Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap); |
2732 | return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2733 | } |
2734 | } |
2735 | |
2736 | // Otherwise couldn't fold anything into this recurrence. Move onto the |
2737 | // next one. |
2738 | } |
2739 | |
2740 | // Okay, it looks like we really DO need an add expr. Check to see if we |
2741 | // already have one, otherwise create a new one. |
2742 | return getOrCreateAddExpr(Ops, Flags); |
2743 | } |
2744 | |
2745 | const SCEV * |
2746 | ScalarEvolution::getOrCreateAddExpr(SmallVectorImpl<const SCEV *> &Ops, |
2747 | SCEV::NoWrapFlags Flags) { |
2748 | FoldingSetNodeID ID; |
2749 | ID.AddInteger(scAddExpr); |
2750 | for (const SCEV *Op : Ops) |
2751 | ID.AddPointer(Op); |
2752 | void *IP = nullptr; |
2753 | SCEVAddExpr *S = |
2754 | static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
2755 | if (!S) { |
2756 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
2757 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
2758 | S = new (SCEVAllocator) |
2759 | SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size()); |
2760 | UniqueSCEVs.InsertNode(S, IP); |
2761 | addToLoopUseLists(S); |
2762 | } |
2763 | S->setNoWrapFlags(Flags); |
2764 | return S; |
2765 | } |
2766 | |
2767 | const SCEV * |
2768 | ScalarEvolution::getOrCreateAddRecExpr(SmallVectorImpl<const SCEV *> &Ops, |
2769 | const Loop *L, SCEV::NoWrapFlags Flags) { |
2770 | FoldingSetNodeID ID; |
2771 | ID.AddInteger(scAddRecExpr); |
2772 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
2773 | ID.AddPointer(Ops[i]); |
2774 | ID.AddPointer(L); |
2775 | void *IP = nullptr; |
2776 | SCEVAddRecExpr *S = |
2777 | static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
2778 | if (!S) { |
2779 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
2780 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
2781 | S = new (SCEVAllocator) |
2782 | SCEVAddRecExpr(ID.Intern(SCEVAllocator), O, Ops.size(), L); |
2783 | UniqueSCEVs.InsertNode(S, IP); |
2784 | addToLoopUseLists(S); |
2785 | } |
2786 | S->setNoWrapFlags(Flags); |
2787 | return S; |
2788 | } |
2789 | |
2790 | const SCEV * |
2791 | ScalarEvolution::getOrCreateMulExpr(SmallVectorImpl<const SCEV *> &Ops, |
2792 | SCEV::NoWrapFlags Flags) { |
2793 | FoldingSetNodeID ID; |
2794 | ID.AddInteger(scMulExpr); |
2795 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
2796 | ID.AddPointer(Ops[i]); |
2797 | void *IP = nullptr; |
2798 | SCEVMulExpr *S = |
2799 | static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP)); |
2800 | if (!S) { |
2801 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
2802 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
2803 | S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator), |
2804 | O, Ops.size()); |
2805 | UniqueSCEVs.InsertNode(S, IP); |
2806 | addToLoopUseLists(S); |
2807 | } |
2808 | S->setNoWrapFlags(Flags); |
2809 | return S; |
2810 | } |
2811 | |
2812 | static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) { |
2813 | uint64_t k = i*j; |
2814 | if (j > 1 && k / j != i) Overflow = true; |
2815 | return k; |
2816 | } |
2817 | |
2818 | /// Compute the result of "n choose k", the binomial coefficient. If an |
2819 | /// intermediate computation overflows, Overflow will be set and the return will |
2820 | /// be garbage. Overflow is not cleared on absence of overflow. |
2821 | static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) { |
2822 | // We use the multiplicative formula: |
2823 | // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 . |
2824 | // At each iteration, we take the n-th term of the numeral and divide by the |
2825 | // (k-n)th term of the denominator. This division will always produce an |
2826 | // integral result, and helps reduce the chance of overflow in the |
2827 | // intermediate computations. However, we can still overflow even when the |
2828 | // final result would fit. |
2829 | |
2830 | if (n == 0 || n == k) return 1; |
2831 | if (k > n) return 0; |
2832 | |
2833 | if (k > n/2) |
2834 | k = n-k; |
2835 | |
2836 | uint64_t r = 1; |
2837 | for (uint64_t i = 1; i <= k; ++i) { |
2838 | r = umul_ov(r, n-(i-1), Overflow); |
2839 | r /= i; |
2840 | } |
2841 | return r; |
2842 | } |
2843 | |
2844 | /// Determine if any of the operands in this SCEV are a constant or if |
2845 | /// any of the add or multiply expressions in this SCEV contain a constant. |
2846 | static bool containsConstantInAddMulChain(const SCEV *StartExpr) { |
2847 | struct FindConstantInAddMulChain { |
2848 | bool FoundConstant = false; |
2849 | |
2850 | bool follow(const SCEV *S) { |
2851 | FoundConstant |= isa<SCEVConstant>(S); |
2852 | return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S); |
2853 | } |
2854 | |
2855 | bool isDone() const { |
2856 | return FoundConstant; |
2857 | } |
2858 | }; |
2859 | |
2860 | FindConstantInAddMulChain F; |
2861 | SCEVTraversal<FindConstantInAddMulChain> ST(F); |
2862 | ST.visitAll(StartExpr); |
2863 | return F.FoundConstant; |
2864 | } |
2865 | |
2866 | /// Get a canonical multiply expression, or something simpler if possible. |
2867 | const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops, |
2868 | SCEV::NoWrapFlags Flags, |
2869 | unsigned Depth) { |
2870 | assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2871, __PRETTY_FUNCTION__)) |
2871 | "only nuw or nsw allowed")((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && "only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2871, __PRETTY_FUNCTION__)); |
2872 | assert(!Ops.empty() && "Cannot get empty mul!")((!Ops.empty() && "Cannot get empty mul!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2872, __PRETTY_FUNCTION__)); |
2873 | if (Ops.size() == 1) return Ops[0]; |
2874 | #ifndef NDEBUG |
2875 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
2876 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
2877 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVMulExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2878, __PRETTY_FUNCTION__)) |
2878 | "SCEVMulExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVMulExpr operand types don't match!") ? static_cast<void > (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 2878, __PRETTY_FUNCTION__)); |
2879 | #endif |
2880 | |
2881 | // Sort by complexity, this groups all similar expression types together. |
2882 | GroupByComplexity(Ops, &LI, DT); |
2883 | |
2884 | Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags); |
2885 | |
2886 | // Limit recursion calls depth. |
2887 | if (Depth > MaxArithDepth) |
2888 | return getOrCreateMulExpr(Ops, Flags); |
2889 | |
2890 | // If there are any constants, fold them together. |
2891 | unsigned Idx = 0; |
2892 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
2893 | |
2894 | if (Ops.size() == 2) |
2895 | // C1*(C2+V) -> C1*C2 + C1*V |
2896 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) |
2897 | // If any of Add's ops are Adds or Muls with a constant, apply this |
2898 | // transformation as well. |
2899 | // |
2900 | // TODO: There are some cases where this transformation is not |
2901 | // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of |
2902 | // this transformation should be narrowed down. |
2903 | if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add)) |
2904 | return getAddExpr(getMulExpr(LHSC, Add->getOperand(0), |
2905 | SCEV::FlagAnyWrap, Depth + 1), |
2906 | getMulExpr(LHSC, Add->getOperand(1), |
2907 | SCEV::FlagAnyWrap, Depth + 1), |
2908 | SCEV::FlagAnyWrap, Depth + 1); |
2909 | |
2910 | ++Idx; |
2911 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
2912 | // We found two constants, fold them together! |
2913 | ConstantInt *Fold = |
2914 | ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt()); |
2915 | Ops[0] = getConstant(Fold); |
2916 | Ops.erase(Ops.begin()+1); // Erase the folded element |
2917 | if (Ops.size() == 1) return Ops[0]; |
2918 | LHSC = cast<SCEVConstant>(Ops[0]); |
2919 | } |
2920 | |
2921 | // If we are left with a constant one being multiplied, strip it off. |
2922 | if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) { |
2923 | Ops.erase(Ops.begin()); |
2924 | --Idx; |
2925 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) { |
2926 | // If we have a multiply of zero, it will always be zero. |
2927 | return Ops[0]; |
2928 | } else if (Ops[0]->isAllOnesValue()) { |
2929 | // If we have a mul by -1 of an add, try distributing the -1 among the |
2930 | // add operands. |
2931 | if (Ops.size() == 2) { |
2932 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) { |
2933 | SmallVector<const SCEV *, 4> NewOps; |
2934 | bool AnyFolded = false; |
2935 | for (const SCEV *AddOp : Add->operands()) { |
2936 | const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap, |
2937 | Depth + 1); |
2938 | if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true; |
2939 | NewOps.push_back(Mul); |
2940 | } |
2941 | if (AnyFolded) |
2942 | return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1); |
2943 | } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) { |
2944 | // Negation preserves a recurrence's no self-wrap property. |
2945 | SmallVector<const SCEV *, 4> Operands; |
2946 | for (const SCEV *AddRecOp : AddRec->operands()) |
2947 | Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap, |
2948 | Depth + 1)); |
2949 | |
2950 | return getAddRecExpr(Operands, AddRec->getLoop(), |
2951 | AddRec->getNoWrapFlags(SCEV::FlagNW)); |
2952 | } |
2953 | } |
2954 | } |
2955 | |
2956 | if (Ops.size() == 1) |
2957 | return Ops[0]; |
2958 | } |
2959 | |
2960 | // Skip over the add expression until we get to a multiply. |
2961 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr) |
2962 | ++Idx; |
2963 | |
2964 | // If there are mul operands inline them all into this expression. |
2965 | if (Idx < Ops.size()) { |
2966 | bool DeletedMul = false; |
2967 | while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) { |
2968 | if (Ops.size() > MulOpsInlineThreshold) |
2969 | break; |
2970 | // If we have an mul, expand the mul operands onto the end of the |
2971 | // operands list. |
2972 | Ops.erase(Ops.begin()+Idx); |
2973 | Ops.append(Mul->op_begin(), Mul->op_end()); |
2974 | DeletedMul = true; |
2975 | } |
2976 | |
2977 | // If we deleted at least one mul, we added operands to the end of the |
2978 | // list, and they are not necessarily sorted. Recurse to resort and |
2979 | // resimplify any operands we just acquired. |
2980 | if (DeletedMul) |
2981 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
2982 | } |
2983 | |
2984 | // If there are any add recurrences in the operands list, see if any other |
2985 | // added values are loop invariant. If so, we can fold them into the |
2986 | // recurrence. |
2987 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr) |
2988 | ++Idx; |
2989 | |
2990 | // Scan over all recurrences, trying to fold loop invariants into them. |
2991 | for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) { |
2992 | // Scan all of the other operands to this mul and add them to the vector |
2993 | // if they are loop invariant w.r.t. the recurrence. |
2994 | SmallVector<const SCEV *, 8> LIOps; |
2995 | const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]); |
2996 | const Loop *AddRecLoop = AddRec->getLoop(); |
2997 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
2998 | if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) { |
2999 | LIOps.push_back(Ops[i]); |
3000 | Ops.erase(Ops.begin()+i); |
3001 | --i; --e; |
3002 | } |
3003 | |
3004 | // If we found some loop invariants, fold them into the recurrence. |
3005 | if (!LIOps.empty()) { |
3006 | // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step} |
3007 | SmallVector<const SCEV *, 4> NewOps; |
3008 | NewOps.reserve(AddRec->getNumOperands()); |
3009 | const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1); |
3010 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) |
3011 | NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i), |
3012 | SCEV::FlagAnyWrap, Depth + 1)); |
3013 | |
3014 | // Build the new addrec. Propagate the NUW and NSW flags if both the |
3015 | // outer mul and the inner addrec are guaranteed to have no overflow. |
3016 | // |
3017 | // No self-wrap cannot be guaranteed after changing the step size, but |
3018 | // will be inferred if either NUW or NSW is true. |
3019 | Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW)); |
3020 | const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags); |
3021 | |
3022 | // If all of the other operands were loop invariant, we are done. |
3023 | if (Ops.size() == 1) return NewRec; |
3024 | |
3025 | // Otherwise, multiply the folded AddRec by the non-invariant parts. |
3026 | for (unsigned i = 0;; ++i) |
3027 | if (Ops[i] == AddRec) { |
3028 | Ops[i] = NewRec; |
3029 | break; |
3030 | } |
3031 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
3032 | } |
3033 | |
3034 | // Okay, if there weren't any loop invariants to be folded, check to see |
3035 | // if there are multiple AddRec's with the same loop induction variable |
3036 | // being multiplied together. If so, we can fold them. |
3037 | |
3038 | // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L> |
3039 | // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [ |
3040 | // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z |
3041 | // ]]],+,...up to x=2n}. |
3042 | // Note that the arguments to choose() are always integers with values |
3043 | // known at compile time, never SCEV objects. |
3044 | // |
3045 | // The implementation avoids pointless extra computations when the two |
3046 | // addrec's are of different length (mathematically, it's equivalent to |
3047 | // an infinite stream of zeros on the right). |
3048 | bool OpsModified = false; |
3049 | for (unsigned OtherIdx = Idx+1; |
3050 | OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]); |
3051 | ++OtherIdx) { |
3052 | const SCEVAddRecExpr *OtherAddRec = |
3053 | dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]); |
3054 | if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop) |
3055 | continue; |
3056 | |
3057 | // Limit max number of arguments to avoid creation of unreasonably big |
3058 | // SCEVAddRecs with very complex operands. |
3059 | if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 > |
3060 | MaxAddRecSize) |
3061 | continue; |
3062 | |
3063 | bool Overflow = false; |
3064 | Type *Ty = AddRec->getType(); |
3065 | bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64; |
3066 | SmallVector<const SCEV*, 7> AddRecOps; |
3067 | for (int x = 0, xe = AddRec->getNumOperands() + |
3068 | OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) { |
3069 | SmallVector <const SCEV *, 7> SumOps; |
3070 | for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) { |
3071 | uint64_t Coeff1 = Choose(x, 2*x - y, Overflow); |
3072 | for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1), |
3073 | ze = std::min(x+1, (int)OtherAddRec->getNumOperands()); |
3074 | z < ze && !Overflow; ++z) { |
3075 | uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow); |
3076 | uint64_t Coeff; |
3077 | if (LargerThan64Bits) |
3078 | Coeff = umul_ov(Coeff1, Coeff2, Overflow); |
3079 | else |
3080 | Coeff = Coeff1*Coeff2; |
3081 | const SCEV *CoeffTerm = getConstant(Ty, Coeff); |
3082 | const SCEV *Term1 = AddRec->getOperand(y-z); |
3083 | const SCEV *Term2 = OtherAddRec->getOperand(z); |
3084 | SumOps.push_back(getMulExpr(CoeffTerm, Term1, Term2, |
3085 | SCEV::FlagAnyWrap, Depth + 1)); |
3086 | } |
3087 | } |
3088 | if (SumOps.empty()) |
3089 | SumOps.push_back(getZero(Ty)); |
3090 | AddRecOps.push_back(getAddExpr(SumOps, SCEV::FlagAnyWrap, Depth + 1)); |
3091 | } |
3092 | if (!Overflow) { |
3093 | const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(), |
3094 | SCEV::FlagAnyWrap); |
3095 | if (Ops.size() == 2) return NewAddRec; |
3096 | Ops[Idx] = NewAddRec; |
3097 | Ops.erase(Ops.begin() + OtherIdx); --OtherIdx; |
3098 | OpsModified = true; |
3099 | AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec); |
3100 | if (!AddRec) |
3101 | break; |
3102 | } |
3103 | } |
3104 | if (OpsModified) |
3105 | return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1); |
3106 | |
3107 | // Otherwise couldn't fold anything into this recurrence. Move onto the |
3108 | // next one. |
3109 | } |
3110 | |
3111 | // Okay, it looks like we really DO need an mul expr. Check to see if we |
3112 | // already have one, otherwise create a new one. |
3113 | return getOrCreateMulExpr(Ops, Flags); |
3114 | } |
3115 | |
3116 | /// Represents an unsigned remainder expression based on unsigned division. |
3117 | const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS, |
3118 | const SCEV *RHS) { |
3119 | assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3121, __PRETTY_FUNCTION__)) |
3120 | getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3121, __PRETTY_FUNCTION__)) |
3121 | "SCEVURemExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVURemExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3121, __PRETTY_FUNCTION__)); |
3122 | |
3123 | // Short-circuit easy cases |
3124 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
3125 | // If constant is one, the result is trivial |
3126 | if (RHSC->getValue()->isOne()) |
3127 | return getZero(LHS->getType()); // X urem 1 --> 0 |
3128 | |
3129 | // If constant is a power of two, fold into a zext(trunc(LHS)). |
3130 | if (RHSC->getAPInt().isPowerOf2()) { |
3131 | Type *FullTy = LHS->getType(); |
3132 | Type *TruncTy = |
3133 | IntegerType::get(getContext(), RHSC->getAPInt().logBase2()); |
3134 | return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy); |
3135 | } |
3136 | } |
3137 | |
3138 | // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y) |
3139 | const SCEV *UDiv = getUDivExpr(LHS, RHS); |
3140 | const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW); |
3141 | return getMinusSCEV(LHS, Mult, SCEV::FlagNUW); |
3142 | } |
3143 | |
3144 | /// Get a canonical unsigned division expression, or something simpler if |
3145 | /// possible. |
3146 | const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS, |
3147 | const SCEV *RHS) { |
3148 | assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3150, __PRETTY_FUNCTION__)) |
3149 | getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3150, __PRETTY_FUNCTION__)) |
3150 | "SCEVUDivExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType (RHS->getType()) && "SCEVUDivExpr operand types don't match!" ) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3150, __PRETTY_FUNCTION__)); |
3151 | |
3152 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
3153 | if (RHSC->getValue()->isOne()) |
3154 | return LHS; // X udiv 1 --> x |
3155 | // If the denominator is zero, the result of the udiv is undefined. Don't |
3156 | // try to analyze it, because the resolution chosen here may differ from |
3157 | // the resolution chosen in other parts of the compiler. |
3158 | if (!RHSC->getValue()->isZero()) { |
3159 | // Determine if the division can be folded into the operands of |
3160 | // its operands. |
3161 | // TODO: Generalize this to non-constants by using known-bits information. |
3162 | Type *Ty = LHS->getType(); |
3163 | unsigned LZ = RHSC->getAPInt().countLeadingZeros(); |
3164 | unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1; |
3165 | // For non-power-of-two values, effectively round the value up to the |
3166 | // nearest power of two. |
3167 | if (!RHSC->getAPInt().isPowerOf2()) |
3168 | ++MaxShiftAmt; |
3169 | IntegerType *ExtTy = |
3170 | IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt); |
3171 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) |
3172 | if (const SCEVConstant *Step = |
3173 | dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) { |
3174 | // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded. |
3175 | const APInt &StepInt = Step->getAPInt(); |
3176 | const APInt &DivInt = RHSC->getAPInt(); |
3177 | if (!StepInt.urem(DivInt) && |
3178 | getZeroExtendExpr(AR, ExtTy) == |
3179 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), |
3180 | getZeroExtendExpr(Step, ExtTy), |
3181 | AR->getLoop(), SCEV::FlagAnyWrap)) { |
3182 | SmallVector<const SCEV *, 4> Operands; |
3183 | for (const SCEV *Op : AR->operands()) |
3184 | Operands.push_back(getUDivExpr(Op, RHS)); |
3185 | return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW); |
3186 | } |
3187 | /// Get a canonical UDivExpr for a recurrence. |
3188 | /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0. |
3189 | // We can currently only fold X%N if X is constant. |
3190 | const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart()); |
3191 | if (StartC && !DivInt.urem(StepInt) && |
3192 | getZeroExtendExpr(AR, ExtTy) == |
3193 | getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy), |
3194 | getZeroExtendExpr(Step, ExtTy), |
3195 | AR->getLoop(), SCEV::FlagAnyWrap)) { |
3196 | const APInt &StartInt = StartC->getAPInt(); |
3197 | const APInt &StartRem = StartInt.urem(StepInt); |
3198 | if (StartRem != 0) |
3199 | LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step, |
3200 | AR->getLoop(), SCEV::FlagNW); |
3201 | } |
3202 | } |
3203 | // (A*B)/C --> A*(B/C) if safe and B/C can be folded. |
3204 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) { |
3205 | SmallVector<const SCEV *, 4> Operands; |
3206 | for (const SCEV *Op : M->operands()) |
3207 | Operands.push_back(getZeroExtendExpr(Op, ExtTy)); |
3208 | if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands)) |
3209 | // Find an operand that's safely divisible. |
3210 | for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) { |
3211 | const SCEV *Op = M->getOperand(i); |
3212 | const SCEV *Div = getUDivExpr(Op, RHSC); |
3213 | if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) { |
3214 | Operands = SmallVector<const SCEV *, 4>(M->op_begin(), |
3215 | M->op_end()); |
3216 | Operands[i] = Div; |
3217 | return getMulExpr(Operands); |
3218 | } |
3219 | } |
3220 | } |
3221 | |
3222 | // (A/B)/C --> A/(B*C) if safe and B*C can be folded. |
3223 | if (const SCEVUDivExpr *OtherDiv = dyn_cast<SCEVUDivExpr>(LHS)) { |
3224 | if (auto *DivisorConstant = |
3225 | dyn_cast<SCEVConstant>(OtherDiv->getRHS())) { |
3226 | bool Overflow = false; |
3227 | APInt NewRHS = |
3228 | DivisorConstant->getAPInt().umul_ov(RHSC->getAPInt(), Overflow); |
3229 | if (Overflow) { |
3230 | return getConstant(RHSC->getType(), 0, false); |
3231 | } |
3232 | return getUDivExpr(OtherDiv->getLHS(), getConstant(NewRHS)); |
3233 | } |
3234 | } |
3235 | |
3236 | // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded. |
3237 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) { |
3238 | SmallVector<const SCEV *, 4> Operands; |
3239 | for (const SCEV *Op : A->operands()) |
3240 | Operands.push_back(getZeroExtendExpr(Op, ExtTy)); |
3241 | if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) { |
3242 | Operands.clear(); |
3243 | for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) { |
3244 | const SCEV *Op = getUDivExpr(A->getOperand(i), RHS); |
3245 | if (isa<SCEVUDivExpr>(Op) || |
3246 | getMulExpr(Op, RHS) != A->getOperand(i)) |
3247 | break; |
3248 | Operands.push_back(Op); |
3249 | } |
3250 | if (Operands.size() == A->getNumOperands()) |
3251 | return getAddExpr(Operands); |
3252 | } |
3253 | } |
3254 | |
3255 | // Fold if both operands are constant. |
3256 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { |
3257 | Constant *LHSCV = LHSC->getValue(); |
3258 | Constant *RHSCV = RHSC->getValue(); |
3259 | return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV, |
3260 | RHSCV))); |
3261 | } |
3262 | } |
3263 | } |
3264 | |
3265 | FoldingSetNodeID ID; |
3266 | ID.AddInteger(scUDivExpr); |
3267 | ID.AddPointer(LHS); |
3268 | ID.AddPointer(RHS); |
3269 | void *IP = nullptr; |
3270 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
3271 | SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator), |
3272 | LHS, RHS); |
3273 | UniqueSCEVs.InsertNode(S, IP); |
3274 | addToLoopUseLists(S); |
3275 | return S; |
3276 | } |
3277 | |
3278 | static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) { |
3279 | APInt A = C1->getAPInt().abs(); |
3280 | APInt B = C2->getAPInt().abs(); |
3281 | uint32_t ABW = A.getBitWidth(); |
3282 | uint32_t BBW = B.getBitWidth(); |
3283 | |
3284 | if (ABW > BBW) |
3285 | B = B.zext(ABW); |
3286 | else if (ABW < BBW) |
3287 | A = A.zext(BBW); |
3288 | |
3289 | return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B)); |
3290 | } |
3291 | |
3292 | /// Get a canonical unsigned division expression, or something simpler if |
3293 | /// possible. There is no representation for an exact udiv in SCEV IR, but we |
3294 | /// can attempt to remove factors from the LHS and RHS. We can't do this when |
3295 | /// it's not exact because the udiv may be clearing bits. |
3296 | const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS, |
3297 | const SCEV *RHS) { |
3298 | // TODO: we could try to find factors in all sorts of things, but for now we |
3299 | // just deal with u/exact (multiply, constant). See SCEVDivision towards the |
3300 | // end of this file for inspiration. |
3301 | |
3302 | const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS); |
3303 | if (!Mul || !Mul->hasNoUnsignedWrap()) |
3304 | return getUDivExpr(LHS, RHS); |
3305 | |
3306 | if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) { |
3307 | // If the mulexpr multiplies by a constant, then that constant must be the |
3308 | // first element of the mulexpr. |
3309 | if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) { |
3310 | if (LHSCst == RHSCst) { |
3311 | SmallVector<const SCEV *, 2> Operands; |
3312 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); |
3313 | return getMulExpr(Operands); |
3314 | } |
3315 | |
3316 | // We can't just assume that LHSCst divides RHSCst cleanly, it could be |
3317 | // that there's a factor provided by one of the other terms. We need to |
3318 | // check. |
3319 | APInt Factor = gcd(LHSCst, RHSCst); |
3320 | if (!Factor.isIntN(1)) { |
3321 | LHSCst = |
3322 | cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor))); |
3323 | RHSCst = |
3324 | cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor))); |
3325 | SmallVector<const SCEV *, 2> Operands; |
3326 | Operands.push_back(LHSCst); |
3327 | Operands.append(Mul->op_begin() + 1, Mul->op_end()); |
3328 | LHS = getMulExpr(Operands); |
3329 | RHS = RHSCst; |
3330 | Mul = dyn_cast<SCEVMulExpr>(LHS); |
3331 | if (!Mul) |
3332 | return getUDivExactExpr(LHS, RHS); |
3333 | } |
3334 | } |
3335 | } |
3336 | |
3337 | for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) { |
3338 | if (Mul->getOperand(i) == RHS) { |
3339 | SmallVector<const SCEV *, 2> Operands; |
3340 | Operands.append(Mul->op_begin(), Mul->op_begin() + i); |
3341 | Operands.append(Mul->op_begin() + i + 1, Mul->op_end()); |
3342 | return getMulExpr(Operands); |
3343 | } |
3344 | } |
3345 | |
3346 | return getUDivExpr(LHS, RHS); |
3347 | } |
3348 | |
3349 | /// Get an add recurrence expression for the specified loop. Simplify the |
3350 | /// expression as much as possible. |
3351 | const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step, |
3352 | const Loop *L, |
3353 | SCEV::NoWrapFlags Flags) { |
3354 | SmallVector<const SCEV *, 4> Operands; |
3355 | Operands.push_back(Start); |
3356 | if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step)) |
3357 | if (StepChrec->getLoop() == L) { |
3358 | Operands.append(StepChrec->op_begin(), StepChrec->op_end()); |
3359 | return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW)); |
3360 | } |
3361 | |
3362 | Operands.push_back(Step); |
3363 | return getAddRecExpr(Operands, L, Flags); |
3364 | } |
3365 | |
3366 | /// Get an add recurrence expression for the specified loop. Simplify the |
3367 | /// expression as much as possible. |
3368 | const SCEV * |
3369 | ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, |
3370 | const Loop *L, SCEV::NoWrapFlags Flags) { |
3371 | if (Operands.size() == 1) return Operands[0]; |
3372 | #ifndef NDEBUG |
3373 | Type *ETy = getEffectiveSCEVType(Operands[0]->getType()); |
3374 | for (unsigned i = 1, e = Operands.size(); i != e; ++i) |
3375 | assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&((getEffectiveSCEVType(Operands[i]->getType()) == ETy && "SCEVAddRecExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3376, __PRETTY_FUNCTION__)) |
3376 | "SCEVAddRecExpr operand types don't match!")((getEffectiveSCEVType(Operands[i]->getType()) == ETy && "SCEVAddRecExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3376, __PRETTY_FUNCTION__)); |
3377 | for (unsigned i = 0, e = Operands.size(); i != e; ++i) |
3378 | assert(isLoopInvariant(Operands[i], L) &&((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3379, __PRETTY_FUNCTION__)) |
3379 | "SCEVAddRecExpr operand is not loop-invariant!")((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3379, __PRETTY_FUNCTION__)); |
3380 | #endif |
3381 | |
3382 | if (Operands.back()->isZero()) { |
3383 | Operands.pop_back(); |
3384 | return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X |
3385 | } |
3386 | |
3387 | // It's tempting to want to call getMaxBackedgeTakenCount count here and |
3388 | // use that information to infer NUW and NSW flags. However, computing a |
3389 | // BE count requires calling getAddRecExpr, so we may not yet have a |
3390 | // meaningful BE count at this point (and if we don't, we'd be stuck |
3391 | // with a SCEVCouldNotCompute as the cached BE count). |
3392 | |
3393 | Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags); |
3394 | |
3395 | // Canonicalize nested AddRecs in by nesting them in order of loop depth. |
3396 | if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) { |
3397 | const Loop *NestedLoop = NestedAR->getLoop(); |
3398 | if (L->contains(NestedLoop) |
3399 | ? (L->getLoopDepth() < NestedLoop->getLoopDepth()) |
3400 | : (!NestedLoop->contains(L) && |
3401 | DT.dominates(L->getHeader(), NestedLoop->getHeader()))) { |
3402 | SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(), |
3403 | NestedAR->op_end()); |
3404 | Operands[0] = NestedAR->getStart(); |
3405 | // AddRecs require their operands be loop-invariant with respect to their |
3406 | // loops. Don't perform this transformation if it would break this |
3407 | // requirement. |
3408 | bool AllInvariant = all_of( |
3409 | Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); }); |
3410 | |
3411 | if (AllInvariant) { |
3412 | // Create a recurrence for the outer loop with the same step size. |
3413 | // |
3414 | // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the |
3415 | // inner recurrence has the same property. |
3416 | SCEV::NoWrapFlags OuterFlags = |
3417 | maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags()); |
3418 | |
3419 | NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags); |
3420 | AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) { |
3421 | return isLoopInvariant(Op, NestedLoop); |
3422 | }); |
3423 | |
3424 | if (AllInvariant) { |
3425 | // Ok, both add recurrences are valid after the transformation. |
3426 | // |
3427 | // The inner recurrence keeps its NW flag but only keeps NUW/NSW if |
3428 | // the outer recurrence has the same property. |
3429 | SCEV::NoWrapFlags InnerFlags = |
3430 | maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags); |
3431 | return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags); |
3432 | } |
3433 | } |
3434 | // Reset Operands to its original state. |
3435 | Operands[0] = NestedAR; |
3436 | } |
3437 | } |
3438 | |
3439 | // Okay, it looks like we really DO need an addrec expr. Check to see if we |
3440 | // already have one, otherwise create a new one. |
3441 | return getOrCreateAddRecExpr(Operands, L, Flags); |
3442 | } |
3443 | |
3444 | const SCEV * |
3445 | ScalarEvolution::getGEPExpr(GEPOperator *GEP, |
3446 | const SmallVectorImpl<const SCEV *> &IndexExprs) { |
3447 | const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand()); |
3448 | // getSCEV(Base)->getType() has the same address space as Base->getType() |
3449 | // because SCEV::getType() preserves the address space. |
3450 | Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType()); |
3451 | // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP |
3452 | // instruction to its SCEV, because the Instruction may be guarded by control |
3453 | // flow and the no-overflow bits may not be valid for the expression in any |
3454 | // context. This can be fixed similarly to how these flags are handled for |
3455 | // adds. |
3456 | SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW |
3457 | : SCEV::FlagAnyWrap; |
3458 | |
3459 | const SCEV *TotalOffset = getZero(IntPtrTy); |
3460 | // The array size is unimportant. The first thing we do on CurTy is getting |
3461 | // its element type. |
3462 | Type *CurTy = ArrayType::get(GEP->getSourceElementType(), 0); |
3463 | for (const SCEV *IndexExpr : IndexExprs) { |
3464 | // Compute the (potentially symbolic) offset in bytes for this index. |
3465 | if (StructType *STy = dyn_cast<StructType>(CurTy)) { |
3466 | // For a struct, add the member offset. |
3467 | ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue(); |
3468 | unsigned FieldNo = Index->getZExtValue(); |
3469 | const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo); |
3470 | |
3471 | // Add the field offset to the running total offset. |
3472 | TotalOffset = getAddExpr(TotalOffset, FieldOffset); |
3473 | |
3474 | // Update CurTy to the type of the field at Index. |
3475 | CurTy = STy->getTypeAtIndex(Index); |
3476 | } else { |
3477 | // Update CurTy to its element type. |
3478 | CurTy = cast<SequentialType>(CurTy)->getElementType(); |
3479 | // For an array, add the element offset, explicitly scaled. |
3480 | const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy); |
3481 | // Getelementptr indices are signed. |
3482 | IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy); |
3483 | |
3484 | // Multiply the index by the element size to compute the element offset. |
3485 | const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap); |
3486 | |
3487 | // Add the element offset to the running total offset. |
3488 | TotalOffset = getAddExpr(TotalOffset, LocalOffset); |
3489 | } |
3490 | } |
3491 | |
3492 | // Add the total offset from all the GEP indices to the base. |
3493 | return getAddExpr(BaseExpr, TotalOffset, Wrap); |
3494 | } |
3495 | |
3496 | const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS, |
3497 | const SCEV *RHS) { |
3498 | SmallVector<const SCEV *, 2> Ops = {LHS, RHS}; |
3499 | return getSMaxExpr(Ops); |
3500 | } |
3501 | |
3502 | const SCEV * |
3503 | ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { |
3504 | assert(!Ops.empty() && "Cannot get empty smax!")((!Ops.empty() && "Cannot get empty smax!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty smax!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3504, __PRETTY_FUNCTION__)); |
3505 | if (Ops.size() == 1) return Ops[0]; |
3506 | #ifndef NDEBUG |
3507 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
3508 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
3509 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVSMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3510, __PRETTY_FUNCTION__)) |
3510 | "SCEVSMaxExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVSMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3510, __PRETTY_FUNCTION__)); |
3511 | #endif |
3512 | |
3513 | // Sort by complexity, this groups all similar expression types together. |
3514 | GroupByComplexity(Ops, &LI, DT); |
3515 | |
3516 | // If there are any constants, fold them together. |
3517 | unsigned Idx = 0; |
3518 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
3519 | ++Idx; |
3520 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3520, __PRETTY_FUNCTION__)); |
3521 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
3522 | // We found two constants, fold them together! |
3523 | ConstantInt *Fold = ConstantInt::get( |
3524 | getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt())); |
3525 | Ops[0] = getConstant(Fold); |
3526 | Ops.erase(Ops.begin()+1); // Erase the folded element |
3527 | if (Ops.size() == 1) return Ops[0]; |
3528 | LHSC = cast<SCEVConstant>(Ops[0]); |
3529 | } |
3530 | |
3531 | // If we are left with a constant minimum-int, strip it off. |
3532 | if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) { |
3533 | Ops.erase(Ops.begin()); |
3534 | --Idx; |
3535 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) { |
3536 | // If we have an smax with a constant maximum-int, it will always be |
3537 | // maximum-int. |
3538 | return Ops[0]; |
3539 | } |
3540 | |
3541 | if (Ops.size() == 1) return Ops[0]; |
3542 | } |
3543 | |
3544 | // Find the first SMax |
3545 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr) |
3546 | ++Idx; |
3547 | |
3548 | // Check to see if one of the operands is an SMax. If so, expand its operands |
3549 | // onto our operand list, and recurse to simplify. |
3550 | if (Idx < Ops.size()) { |
3551 | bool DeletedSMax = false; |
3552 | while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) { |
3553 | Ops.erase(Ops.begin()+Idx); |
3554 | Ops.append(SMax->op_begin(), SMax->op_end()); |
3555 | DeletedSMax = true; |
3556 | } |
3557 | |
3558 | if (DeletedSMax) |
3559 | return getSMaxExpr(Ops); |
3560 | } |
3561 | |
3562 | // Okay, check to see if the same value occurs in the operand list twice. If |
3563 | // so, delete one. Since we sorted the list, these values are required to |
3564 | // be adjacent. |
3565 | for (unsigned i = 0, e = Ops.size()-1; i != e; ++i) |
3566 | // X smax Y smax Y --> X smax Y |
3567 | // X smax Y --> X, if X is always greater than Y |
3568 | if (Ops[i] == Ops[i+1] || |
3569 | isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) { |
3570 | Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2); |
3571 | --i; --e; |
3572 | } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) { |
3573 | Ops.erase(Ops.begin()+i, Ops.begin()+i+1); |
3574 | --i; --e; |
3575 | } |
3576 | |
3577 | if (Ops.size() == 1) return Ops[0]; |
3578 | |
3579 | assert(!Ops.empty() && "Reduced smax down to nothing!")((!Ops.empty() && "Reduced smax down to nothing!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3579, __PRETTY_FUNCTION__)); |
3580 | |
3581 | // Okay, it looks like we really DO need an smax expr. Check to see if we |
3582 | // already have one, otherwise create a new one. |
3583 | FoldingSetNodeID ID; |
3584 | ID.AddInteger(scSMaxExpr); |
3585 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
3586 | ID.AddPointer(Ops[i]); |
3587 | void *IP = nullptr; |
3588 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
3589 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
3590 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
3591 | SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator), |
3592 | O, Ops.size()); |
3593 | UniqueSCEVs.InsertNode(S, IP); |
3594 | addToLoopUseLists(S); |
3595 | return S; |
3596 | } |
3597 | |
3598 | const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS, |
3599 | const SCEV *RHS) { |
3600 | SmallVector<const SCEV *, 2> Ops = {LHS, RHS}; |
3601 | return getUMaxExpr(Ops); |
3602 | } |
3603 | |
3604 | const SCEV * |
3605 | ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) { |
3606 | assert(!Ops.empty() && "Cannot get empty umax!")((!Ops.empty() && "Cannot get empty umax!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty umax!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3606, __PRETTY_FUNCTION__)); |
3607 | if (Ops.size() == 1) return Ops[0]; |
3608 | #ifndef NDEBUG |
3609 | Type *ETy = getEffectiveSCEVType(Ops[0]->getType()); |
3610 | for (unsigned i = 1, e = Ops.size(); i != e; ++i) |
3611 | assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVUMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3612, __PRETTY_FUNCTION__)) |
3612 | "SCEVUMaxExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy && "SCEVUMaxExpr operand types don't match!") ? static_cast< void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3612, __PRETTY_FUNCTION__)); |
3613 | #endif |
3614 | |
3615 | // Sort by complexity, this groups all similar expression types together. |
3616 | GroupByComplexity(Ops, &LI, DT); |
3617 | |
3618 | // If there are any constants, fold them together. |
3619 | unsigned Idx = 0; |
3620 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) { |
3621 | ++Idx; |
3622 | assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail ("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3622, __PRETTY_FUNCTION__)); |
3623 | while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) { |
3624 | // We found two constants, fold them together! |
3625 | ConstantInt *Fold = ConstantInt::get( |
3626 | getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt())); |
3627 | Ops[0] = getConstant(Fold); |
3628 | Ops.erase(Ops.begin()+1); // Erase the folded element |
3629 | if (Ops.size() == 1) return Ops[0]; |
3630 | LHSC = cast<SCEVConstant>(Ops[0]); |
3631 | } |
3632 | |
3633 | // If we are left with a constant minimum-int, strip it off. |
3634 | if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) { |
3635 | Ops.erase(Ops.begin()); |
3636 | --Idx; |
3637 | } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) { |
3638 | // If we have an umax with a constant maximum-int, it will always be |
3639 | // maximum-int. |
3640 | return Ops[0]; |
3641 | } |
3642 | |
3643 | if (Ops.size() == 1) return Ops[0]; |
3644 | } |
3645 | |
3646 | // Find the first UMax |
3647 | while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr) |
3648 | ++Idx; |
3649 | |
3650 | // Check to see if one of the operands is a UMax. If so, expand its operands |
3651 | // onto our operand list, and recurse to simplify. |
3652 | if (Idx < Ops.size()) { |
3653 | bool DeletedUMax = false; |
3654 | while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) { |
3655 | Ops.erase(Ops.begin()+Idx); |
3656 | Ops.append(UMax->op_begin(), UMax->op_end()); |
3657 | DeletedUMax = true; |
3658 | } |
3659 | |
3660 | if (DeletedUMax) |
3661 | return getUMaxExpr(Ops); |
3662 | } |
3663 | |
3664 | // Okay, check to see if the same value occurs in the operand list twice. If |
3665 | // so, delete one. Since we sorted the list, these values are required to |
3666 | // be adjacent. |
3667 | for (unsigned i = 0, e = Ops.size()-1; i != e; ++i) |
3668 | // X umax Y umax Y --> X umax Y |
3669 | // X umax Y --> X, if X is always greater than Y |
3670 | if (Ops[i] == Ops[i + 1] || isKnownViaNonRecursiveReasoning( |
3671 | ICmpInst::ICMP_UGE, Ops[i], Ops[i + 1])) { |
3672 | Ops.erase(Ops.begin() + i + 1, Ops.begin() + i + 2); |
3673 | --i; --e; |
3674 | } else if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, Ops[i], |
3675 | Ops[i + 1])) { |
3676 | Ops.erase(Ops.begin() + i, Ops.begin() + i + 1); |
3677 | --i; --e; |
3678 | } |
3679 | |
3680 | if (Ops.size() == 1) return Ops[0]; |
3681 | |
3682 | assert(!Ops.empty() && "Reduced umax down to nothing!")((!Ops.empty() && "Reduced umax down to nothing!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"Reduced umax down to nothing!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3682, __PRETTY_FUNCTION__)); |
3683 | |
3684 | // Okay, it looks like we really DO need a umax expr. Check to see if we |
3685 | // already have one, otherwise create a new one. |
3686 | FoldingSetNodeID ID; |
3687 | ID.AddInteger(scUMaxExpr); |
3688 | for (unsigned i = 0, e = Ops.size(); i != e; ++i) |
3689 | ID.AddPointer(Ops[i]); |
3690 | void *IP = nullptr; |
3691 | if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S; |
3692 | const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size()); |
3693 | std::uninitialized_copy(Ops.begin(), Ops.end(), O); |
3694 | SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator), |
3695 | O, Ops.size()); |
3696 | UniqueSCEVs.InsertNode(S, IP); |
3697 | addToLoopUseLists(S); |
3698 | return S; |
3699 | } |
3700 | |
3701 | const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS, |
3702 | const SCEV *RHS) { |
3703 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; |
3704 | return getSMinExpr(Ops); |
3705 | } |
3706 | |
3707 | const SCEV *ScalarEvolution::getSMinExpr(SmallVectorImpl<const SCEV *> &Ops) { |
3708 | // ~smax(~x, ~y, ~z) == smin(x, y, z). |
3709 | SmallVector<const SCEV *, 2> NotOps; |
3710 | for (auto *S : Ops) |
3711 | NotOps.push_back(getNotSCEV(S)); |
3712 | return getNotSCEV(getSMaxExpr(NotOps)); |
3713 | } |
3714 | |
3715 | const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS, |
3716 | const SCEV *RHS) { |
3717 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; |
3718 | return getUMinExpr(Ops); |
3719 | } |
3720 | |
3721 | const SCEV *ScalarEvolution::getUMinExpr(SmallVectorImpl<const SCEV *> &Ops) { |
3722 | assert(!Ops.empty() && "At least one operand must be!")((!Ops.empty() && "At least one operand must be!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"At least one operand must be!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3722, __PRETTY_FUNCTION__)); |
3723 | // Trivial case. |
3724 | if (Ops.size() == 1) |
3725 | return Ops[0]; |
3726 | |
3727 | // ~umax(~x, ~y, ~z) == umin(x, y, z). |
3728 | SmallVector<const SCEV *, 2> NotOps; |
3729 | for (auto *S : Ops) |
3730 | NotOps.push_back(getNotSCEV(S)); |
3731 | return getNotSCEV(getUMaxExpr(NotOps)); |
3732 | } |
3733 | |
3734 | const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) { |
3735 | // We can bypass creating a target-independent |
3736 | // constant expression and then folding it back into a ConstantInt. |
3737 | // This is just a compile-time optimization. |
3738 | return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy)); |
3739 | } |
3740 | |
3741 | const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy, |
3742 | StructType *STy, |
3743 | unsigned FieldNo) { |
3744 | // We can bypass creating a target-independent |
3745 | // constant expression and then folding it back into a ConstantInt. |
3746 | // This is just a compile-time optimization. |
3747 | return getConstant( |
3748 | IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo)); |
3749 | } |
3750 | |
3751 | const SCEV *ScalarEvolution::getUnknown(Value *V) { |
3752 | // Don't attempt to do anything other than create a SCEVUnknown object |
3753 | // here. createSCEV only calls getUnknown after checking for all other |
3754 | // interesting possibilities, and any other code that calls getUnknown |
3755 | // is doing so in order to hide a value from SCEV canonicalization. |
3756 | |
3757 | FoldingSetNodeID ID; |
3758 | ID.AddInteger(scUnknown); |
3759 | ID.AddPointer(V); |
3760 | void *IP = nullptr; |
3761 | if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) { |
3762 | assert(cast<SCEVUnknown>(S)->getValue() == V &&((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!" ) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3763, __PRETTY_FUNCTION__)) |
3763 | "Stale SCEVUnknown in uniquing map!")((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!" ) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3763, __PRETTY_FUNCTION__)); |
3764 | return S; |
3765 | } |
3766 | SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this, |
3767 | FirstUnknown); |
3768 | FirstUnknown = cast<SCEVUnknown>(S); |
3769 | UniqueSCEVs.InsertNode(S, IP); |
3770 | return S; |
3771 | } |
3772 | |
3773 | //===----------------------------------------------------------------------===// |
3774 | // Basic SCEV Analysis and PHI Idiom Recognition Code |
3775 | // |
3776 | |
3777 | /// Test if values of the given type are analyzable within the SCEV |
3778 | /// framework. This primarily includes integer types, and it can optionally |
3779 | /// include pointer types if the ScalarEvolution class has access to |
3780 | /// target-specific information. |
3781 | bool ScalarEvolution::isSCEVable(Type *Ty) const { |
3782 | // Integers and pointers are always SCEVable. |
3783 | return Ty->isIntOrPtrTy(); |
3784 | } |
3785 | |
3786 | /// Return the size in bits of the specified type, for which isSCEVable must |
3787 | /// return true. |
3788 | uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const { |
3789 | assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast <void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3789, __PRETTY_FUNCTION__)); |
3790 | if (Ty->isPointerTy()) |
3791 | return getDataLayout().getIndexTypeSizeInBits(Ty); |
3792 | return getDataLayout().getTypeSizeInBits(Ty); |
3793 | } |
3794 | |
3795 | /// Return a type with the same bitwidth as the given type and which represents |
3796 | /// how SCEV will treat the given type, for which isSCEVable must return |
3797 | /// true. For pointer types, this is the pointer-sized integer type. |
3798 | Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const { |
3799 | assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast <void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3799, __PRETTY_FUNCTION__)); |
3800 | |
3801 | if (Ty->isIntegerTy()) |
3802 | return Ty; |
3803 | |
3804 | // The only other support type is pointer. |
3805 | assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")((Ty->isPointerTy() && "Unexpected non-pointer non-integer type!" ) ? static_cast<void> (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3805, __PRETTY_FUNCTION__)); |
3806 | return getDataLayout().getIntPtrType(Ty); |
3807 | } |
3808 | |
3809 | Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const { |
3810 | return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2; |
3811 | } |
3812 | |
3813 | const SCEV *ScalarEvolution::getCouldNotCompute() { |
3814 | return CouldNotCompute.get(); |
3815 | } |
3816 | |
3817 | bool ScalarEvolution::checkValidity(const SCEV *S) const { |
3818 | bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) { |
3819 | auto *SU = dyn_cast<SCEVUnknown>(S); |
3820 | return SU && SU->getValue() == nullptr; |
3821 | }); |
3822 | |
3823 | return !ContainsNulls; |
3824 | } |
3825 | |
3826 | bool ScalarEvolution::containsAddRecurrence(const SCEV *S) { |
3827 | HasRecMapType::iterator I = HasRecMap.find(S); |
3828 | if (I != HasRecMap.end()) |
3829 | return I->second; |
3830 | |
3831 | bool FoundAddRec = SCEVExprContains(S, isa<SCEVAddRecExpr, const SCEV *>); |
3832 | HasRecMap.insert({S, FoundAddRec}); |
3833 | return FoundAddRec; |
3834 | } |
3835 | |
3836 | /// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}. |
3837 | /// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an |
3838 | /// offset I, then return {S', I}, else return {\p S, nullptr}. |
3839 | static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) { |
3840 | const auto *Add = dyn_cast<SCEVAddExpr>(S); |
3841 | if (!Add) |
3842 | return {S, nullptr}; |
3843 | |
3844 | if (Add->getNumOperands() != 2) |
3845 | return {S, nullptr}; |
3846 | |
3847 | auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0)); |
3848 | if (!ConstOp) |
3849 | return {S, nullptr}; |
3850 | |
3851 | return {Add->getOperand(1), ConstOp->getValue()}; |
3852 | } |
3853 | |
3854 | /// Return the ValueOffsetPair set for \p S. \p S can be represented |
3855 | /// by the value and offset from any ValueOffsetPair in the set. |
3856 | SetVector<ScalarEvolution::ValueOffsetPair> * |
3857 | ScalarEvolution::getSCEVValues(const SCEV *S) { |
3858 | ExprValueMapType::iterator SI = ExprValueMap.find_as(S); |
3859 | if (SI == ExprValueMap.end()) |
3860 | return nullptr; |
3861 | #ifndef NDEBUG |
3862 | if (VerifySCEVMap) { |
3863 | // Check there is no dangling Value in the set returned. |
3864 | for (const auto &VE : SI->second) |
3865 | assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3865, __PRETTY_FUNCTION__)); |
3866 | } |
3867 | #endif |
3868 | return &SI->second; |
3869 | } |
3870 | |
3871 | /// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V) |
3872 | /// cannot be used separately. eraseValueFromMap should be used to remove |
3873 | /// V from ValueExprMap and ExprValueMap at the same time. |
3874 | void ScalarEvolution::eraseValueFromMap(Value *V) { |
3875 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); |
3876 | if (I != ValueExprMap.end()) { |
3877 | const SCEV *S = I->second; |
3878 | // Remove {V, 0} from the set of ExprValueMap[S] |
3879 | if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S)) |
3880 | SV->remove({V, nullptr}); |
3881 | |
3882 | // Remove {V, Offset} from the set of ExprValueMap[Stripped] |
3883 | const SCEV *Stripped; |
3884 | ConstantInt *Offset; |
3885 | std::tie(Stripped, Offset) = splitAddExpr(S); |
3886 | if (Offset != nullptr) { |
3887 | if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped)) |
3888 | SV->remove({V, Offset}); |
3889 | } |
3890 | ValueExprMap.erase(V); |
3891 | } |
3892 | } |
3893 | |
3894 | /// Check whether value has nuw/nsw/exact set but SCEV does not. |
3895 | /// TODO: In reality it is better to check the poison recursevely |
3896 | /// but this is better than nothing. |
3897 | static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) { |
3898 | if (auto *I = dyn_cast<Instruction>(V)) { |
3899 | if (isa<OverflowingBinaryOperator>(I)) { |
3900 | if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) { |
3901 | if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap()) |
3902 | return true; |
3903 | if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap()) |
3904 | return true; |
3905 | } |
3906 | } else if (isa<PossiblyExactOperator>(I) && I->isExact()) |
3907 | return true; |
3908 | } |
3909 | return false; |
3910 | } |
3911 | |
3912 | /// Return an existing SCEV if it exists, otherwise analyze the expression and |
3913 | /// create a new one. |
3914 | const SCEV *ScalarEvolution::getSCEV(Value *V) { |
3915 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3915, __PRETTY_FUNCTION__)); |
3916 | |
3917 | const SCEV *S = getExistingSCEV(V); |
3918 | if (S == nullptr) { |
3919 | S = createSCEV(V); |
3920 | // During PHI resolution, it is possible to create two SCEVs for the same |
3921 | // V, so it is needed to double check whether V->S is inserted into |
3922 | // ValueExprMap before insert S->{V, 0} into ExprValueMap. |
3923 | std::pair<ValueExprMapType::iterator, bool> Pair = |
3924 | ValueExprMap.insert({SCEVCallbackVH(V, this), S}); |
3925 | if (Pair.second && !SCEVLostPoisonFlags(S, V)) { |
3926 | ExprValueMap[S].insert({V, nullptr}); |
3927 | |
3928 | // If S == Stripped + Offset, add Stripped -> {V, Offset} into |
3929 | // ExprValueMap. |
3930 | const SCEV *Stripped = S; |
3931 | ConstantInt *Offset = nullptr; |
3932 | std::tie(Stripped, Offset) = splitAddExpr(S); |
3933 | // If stripped is SCEVUnknown, don't bother to save |
3934 | // Stripped -> {V, offset}. It doesn't simplify and sometimes even |
3935 | // increase the complexity of the expansion code. |
3936 | // If V is GetElementPtrInst, don't save Stripped -> {V, offset} |
3937 | // because it may generate add/sub instead of GEP in SCEV expansion. |
3938 | if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) && |
3939 | !isa<GetElementPtrInst>(V)) |
3940 | ExprValueMap[Stripped].insert({V, Offset}); |
3941 | } |
3942 | } |
3943 | return S; |
3944 | } |
3945 | |
3946 | const SCEV *ScalarEvolution::getExistingSCEV(Value *V) { |
3947 | assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!" ) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 3947, __PRETTY_FUNCTION__)); |
3948 | |
3949 | ValueExprMapType::iterator I = ValueExprMap.find_as(V); |
3950 | if (I != ValueExprMap.end()) { |
3951 | const SCEV *S = I->second; |
3952 | if (checkValidity(S)) |
3953 | return S; |
3954 | eraseValueFromMap(V); |
3955 | forgetMemoizedResults(S); |
3956 | } |
3957 | return nullptr; |
3958 | } |
3959 | |
3960 | /// Return a SCEV corresponding to -V = -1*V |
3961 | const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V, |
3962 | SCEV::NoWrapFlags Flags) { |
3963 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) |
3964 | return getConstant( |
3965 | cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue()))); |
3966 | |
3967 | Type *Ty = V->getType(); |
3968 | Ty = getEffectiveSCEVType(Ty); |
3969 | return getMulExpr( |
3970 | V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags); |
3971 | } |
3972 | |
3973 | /// Return a SCEV corresponding to ~V = -1-V |
3974 | const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) { |
3975 | if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V)) |
3976 | return getConstant( |
3977 | cast<ConstantInt>(ConstantExpr::getNot(VC->getValue()))); |
3978 | |
3979 | Type *Ty = V->getType(); |
3980 | Ty = getEffectiveSCEVType(Ty); |
3981 | const SCEV *AllOnes = |
3982 | getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))); |
3983 | return getMinusSCEV(AllOnes, V); |
3984 | } |
3985 | |
3986 | const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS, |
3987 | SCEV::NoWrapFlags Flags, |
3988 | unsigned Depth) { |
3989 | // Fast path: X - X --> 0. |
3990 | if (LHS == RHS) |
3991 | return getZero(LHS->getType()); |
3992 | |
3993 | // We represent LHS - RHS as LHS + (-1)*RHS. This transformation |
3994 | // makes it so that we cannot make much use of NUW. |
3995 | auto AddFlags = SCEV::FlagAnyWrap; |
3996 | const bool RHSIsNotMinSigned = |
3997 | !getSignedRangeMin(RHS).isMinSignedValue(); |
3998 | if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) { |
3999 | // Let M be the minimum representable signed value. Then (-1)*RHS |
4000 | // signed-wraps if and only if RHS is M. That can happen even for |
4001 | // a NSW subtraction because e.g. (-1)*M signed-wraps even though |
4002 | // -1 - M does not. So to transfer NSW from LHS - RHS to LHS + |
4003 | // (-1)*RHS, we need to prove that RHS != M. |
4004 | // |
4005 | // If LHS is non-negative and we know that LHS - RHS does not |
4006 | // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap |
4007 | // either by proving that RHS > M or that LHS >= 0. |
4008 | if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) { |
4009 | AddFlags = SCEV::FlagNSW; |
4010 | } |
4011 | } |
4012 | |
4013 | // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS - |
4014 | // RHS is NSW and LHS >= 0. |
4015 | // |
4016 | // The difficulty here is that the NSW flag may have been proven |
4017 | // relative to a loop that is to be found in a recurrence in LHS and |
4018 | // not in RHS. Applying NSW to (-1)*M may then let the NSW have a |
4019 | // larger scope than intended. |
4020 | auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap; |
4021 | |
4022 | return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth); |
4023 | } |
4024 | |
4025 | const SCEV * |
4026 | ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) { |
4027 | Type *SrcTy = V->getType(); |
4028 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4029, __PRETTY_FUNCTION__)) |
4029 | "Cannot truncate or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4029, __PRETTY_FUNCTION__)); |
4030 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
4031 | return V; // No conversion |
4032 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) |
4033 | return getTruncateExpr(V, Ty); |
4034 | return getZeroExtendExpr(V, Ty); |
4035 | } |
4036 | |
4037 | const SCEV * |
4038 | ScalarEvolution::getTruncateOrSignExtend(const SCEV *V, |
4039 | Type *Ty) { |
4040 | Type *SrcTy = V->getType(); |
4041 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4042, __PRETTY_FUNCTION__)) |
4042 | "Cannot truncate or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or zero extend with non-integer arguments!" ) ? static_cast<void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4042, __PRETTY_FUNCTION__)); |
4043 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
4044 | return V; // No conversion |
4045 | if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty)) |
4046 | return getTruncateExpr(V, Ty); |
4047 | return getSignExtendExpr(V, Ty); |
4048 | } |
4049 | |
4050 | const SCEV * |
4051 | ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) { |
4052 | Type *SrcTy = V->getType(); |
4053 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4054, __PRETTY_FUNCTION__)) |
4054 | "Cannot noop or zero extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or zero extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or zero extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4054, __PRETTY_FUNCTION__)); |
4055 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrZeroExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4056, __PRETTY_FUNCTION__)) |
4056 | "getNoopOrZeroExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrZeroExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4056, __PRETTY_FUNCTION__)); |
4057 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
4058 | return V; // No conversion |
4059 | return getZeroExtendExpr(V, Ty); |
4060 | } |
4061 | |
4062 | const SCEV * |
4063 | ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) { |
4064 | Type *SrcTy = V->getType(); |
4065 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4066, __PRETTY_FUNCTION__)) |
4066 | "Cannot noop or sign extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or sign extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or sign extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4066, __PRETTY_FUNCTION__)); |
4067 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrSignExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4068, __PRETTY_FUNCTION__)) |
4068 | "getNoopOrSignExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrSignExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4068, __PRETTY_FUNCTION__)); |
4069 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
4070 | return V; // No conversion |
4071 | return getSignExtendExpr(V, Ty); |
4072 | } |
4073 | |
4074 | const SCEV * |
4075 | ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) { |
4076 | Type *SrcTy = V->getType(); |
4077 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4078, __PRETTY_FUNCTION__)) |
4078 | "Cannot noop or any extend with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot noop or any extend with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot noop or any extend with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4078, __PRETTY_FUNCTION__)); |
4079 | assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrAnyExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4080, __PRETTY_FUNCTION__)) |
4080 | "getNoopOrAnyExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && "getNoopOrAnyExtend cannot truncate!") ? static_cast<void > (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4080, __PRETTY_FUNCTION__)); |
4081 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
4082 | return V; // No conversion |
4083 | return getAnyExtendExpr(V, Ty); |
4084 | } |
4085 | |
4086 | const SCEV * |
4087 | ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) { |
4088 | Type *SrcTy = V->getType(); |
4089 | assert(SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() &&((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4090, __PRETTY_FUNCTION__)) |
4090 | "Cannot truncate or noop with non-integer arguments!")((SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && "Cannot truncate or noop with non-integer arguments!") ? static_cast <void> (0) : __assert_fail ("SrcTy->isIntOrPtrTy() && Ty->isIntOrPtrTy() && \"Cannot truncate or noop with non-integer arguments!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4090, __PRETTY_FUNCTION__)); |
4091 | assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && "getTruncateOrNoop cannot extend!") ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4092, __PRETTY_FUNCTION__)) |
4092 | "getTruncateOrNoop cannot extend!")((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && "getTruncateOrNoop cannot extend!") ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4092, __PRETTY_FUNCTION__)); |
4093 | if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty)) |
4094 | return V; // No conversion |
4095 | return getTruncateExpr(V, Ty); |
4096 | } |
4097 | |
4098 | const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS, |
4099 | const SCEV *RHS) { |
4100 | const SCEV *PromotedLHS = LHS; |
4101 | const SCEV *PromotedRHS = RHS; |
4102 | |
4103 | if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType())) |
4104 | PromotedRHS = getZeroExtendExpr(RHS, LHS->getType()); |
4105 | else |
4106 | PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType()); |
4107 | |
4108 | return getUMaxExpr(PromotedLHS, PromotedRHS); |
4109 | } |
4110 | |
4111 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS, |
4112 | const SCEV *RHS) { |
4113 | SmallVector<const SCEV *, 2> Ops = { LHS, RHS }; |
4114 | return getUMinFromMismatchedTypes(Ops); |
4115 | } |
4116 | |
4117 | const SCEV *ScalarEvolution::getUMinFromMismatchedTypes( |
4118 | SmallVectorImpl<const SCEV *> &Ops) { |
4119 | assert(!Ops.empty() && "At least one operand must be!")((!Ops.empty() && "At least one operand must be!") ? static_cast <void> (0) : __assert_fail ("!Ops.empty() && \"At least one operand must be!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4119, __PRETTY_FUNCTION__)); |
4120 | // Trivial case. |
4121 | if (Ops.size() == 1) |
4122 | return Ops[0]; |
4123 | |
4124 | // Find the max type first. |
4125 | Type *MaxType = nullptr; |
4126 | for (auto *S : Ops) |
4127 | if (MaxType) |
4128 | MaxType = getWiderType(MaxType, S->getType()); |
4129 | else |
4130 | MaxType = S->getType(); |
4131 | |
4132 | // Extend all ops to max type. |
4133 | SmallVector<const SCEV *, 2> PromotedOps; |
4134 | for (auto *S : Ops) |
4135 | PromotedOps.push_back(getNoopOrZeroExtend(S, MaxType)); |
4136 | |
4137 | // Generate umin. |
4138 | return getUMinExpr(PromotedOps); |
4139 | } |
4140 | |
4141 | const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) { |
4142 | // A pointer operand may evaluate to a nonpointer expression, such as null. |
4143 | if (!V->getType()->isPointerTy()) |
4144 | return V; |
4145 | |
4146 | if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) { |
4147 | return getPointerBase(Cast->getOperand()); |
4148 | } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) { |
4149 | const SCEV *PtrOp = nullptr; |
4150 | for (const SCEV *NAryOp : NAry->operands()) { |
4151 | if (NAryOp->getType()->isPointerTy()) { |
4152 | // Cannot find the base of an expression with multiple pointer operands. |
4153 | if (PtrOp) |
4154 | return V; |
4155 | PtrOp = NAryOp; |
4156 | } |
4157 | } |
4158 | if (!PtrOp) |
4159 | return V; |
4160 | return getPointerBase(PtrOp); |
4161 | } |
4162 | return V; |
4163 | } |
4164 | |
4165 | /// Push users of the given Instruction onto the given Worklist. |
4166 | static void |
4167 | PushDefUseChildren(Instruction *I, |
4168 | SmallVectorImpl<Instruction *> &Worklist) { |
4169 | // Push the def-use children onto the Worklist stack. |
4170 | for (User *U : I->users()) |
4171 | Worklist.push_back(cast<Instruction>(U)); |
4172 | } |
4173 | |
4174 | void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) { |
4175 | SmallVector<Instruction *, 16> Worklist; |
4176 | PushDefUseChildren(PN, Worklist); |
4177 | |
4178 | SmallPtrSet<Instruction *, 8> Visited; |
4179 | Visited.insert(PN); |
4180 | while (!Worklist.empty()) { |
4181 | Instruction *I = Worklist.pop_back_val(); |
4182 | if (!Visited.insert(I).second) |
4183 | continue; |
4184 | |
4185 | auto It = ValueExprMap.find_as(static_cast<Value *>(I)); |
4186 | if (It != ValueExprMap.end()) { |
4187 | const SCEV *Old = It->second; |
4188 | |
4189 | // Short-circuit the def-use traversal if the symbolic name |
4190 | // ceases to appear in expressions. |
4191 | if (Old != SymName && !hasOperand(Old, SymName)) |
4192 | continue; |
4193 | |
4194 | // SCEVUnknown for a PHI either means that it has an unrecognized |
4195 | // structure, it's a PHI that's in the progress of being computed |
4196 | // by createNodeForPHI, or it's a single-value PHI. In the first case, |
4197 | // additional loop trip count information isn't going to change anything. |
4198 | // In the second case, createNodeForPHI will perform the necessary |
4199 | // updates on its own when it gets to that point. In the third, we do |
4200 | // want to forget the SCEVUnknown. |
4201 | if (!isa<PHINode>(I) || |
4202 | !isa<SCEVUnknown>(Old) || |
4203 | (I != PN && Old == SymName)) { |
4204 | eraseValueFromMap(It->first); |
4205 | forgetMemoizedResults(Old); |
4206 | } |
4207 | } |
4208 | |
4209 | PushDefUseChildren(I, Worklist); |
4210 | } |
4211 | } |
4212 | |
4213 | namespace { |
4214 | |
4215 | /// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start |
4216 | /// expression in case its Loop is L. If it is not L then |
4217 | /// if IgnoreOtherLoops is true then use AddRec itself |
4218 | /// otherwise rewrite cannot be done. |
4219 | /// If SCEV contains non-invariant unknown SCEV rewrite cannot be done. |
4220 | class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> { |
4221 | public: |
4222 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE, |
4223 | bool IgnoreOtherLoops = true) { |
4224 | SCEVInitRewriter Rewriter(L, SE); |
4225 | const SCEV *Result = Rewriter.visit(S); |
4226 | if (Rewriter.hasSeenLoopVariantSCEVUnknown()) |
4227 | return SE.getCouldNotCompute(); |
4228 | return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops |
4229 | ? SE.getCouldNotCompute() |
4230 | : Result; |
4231 | } |
4232 | |
4233 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
4234 | if (!SE.isLoopInvariant(Expr, L)) |
4235 | SeenLoopVariantSCEVUnknown = true; |
4236 | return Expr; |
4237 | } |
4238 | |
4239 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { |
4240 | // Only re-write AddRecExprs for this loop. |
4241 | if (Expr->getLoop() == L) |
4242 | return Expr->getStart(); |
4243 | SeenOtherLoops = true; |
4244 | return Expr; |
4245 | } |
4246 | |
4247 | bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; } |
4248 | |
4249 | bool hasSeenOtherLoops() { return SeenOtherLoops; } |
4250 | |
4251 | private: |
4252 | explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE) |
4253 | : SCEVRewriteVisitor(SE), L(L) {} |
4254 | |
4255 | const Loop *L; |
4256 | bool SeenLoopVariantSCEVUnknown = false; |
4257 | bool SeenOtherLoops = false; |
4258 | }; |
4259 | |
4260 | /// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post |
4261 | /// increment expression in case its Loop is L. If it is not L then |
4262 | /// use AddRec itself. |
4263 | /// If SCEV contains non-invariant unknown SCEV rewrite cannot be done. |
4264 | class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> { |
4265 | public: |
4266 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) { |
4267 | SCEVPostIncRewriter Rewriter(L, SE); |
4268 | const SCEV *Result = Rewriter.visit(S); |
4269 | return Rewriter.hasSeenLoopVariantSCEVUnknown() |
4270 | ? SE.getCouldNotCompute() |
4271 | : Result; |
4272 | } |
4273 | |
4274 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
4275 | if (!SE.isLoopInvariant(Expr, L)) |
4276 | SeenLoopVariantSCEVUnknown = true; |
4277 | return Expr; |
4278 | } |
4279 | |
4280 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { |
4281 | // Only re-write AddRecExprs for this loop. |
4282 | if (Expr->getLoop() == L) |
4283 | return Expr->getPostIncExpr(SE); |
4284 | SeenOtherLoops = true; |
4285 | return Expr; |
4286 | } |
4287 | |
4288 | bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; } |
4289 | |
4290 | bool hasSeenOtherLoops() { return SeenOtherLoops; } |
4291 | |
4292 | private: |
4293 | explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE) |
4294 | : SCEVRewriteVisitor(SE), L(L) {} |
4295 | |
4296 | const Loop *L; |
4297 | bool SeenLoopVariantSCEVUnknown = false; |
4298 | bool SeenOtherLoops = false; |
4299 | }; |
4300 | |
4301 | /// This class evaluates the compare condition by matching it against the |
4302 | /// condition of loop latch. If there is a match we assume a true value |
4303 | /// for the condition while building SCEV nodes. |
4304 | class SCEVBackedgeConditionFolder |
4305 | : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> { |
4306 | public: |
4307 | static const SCEV *rewrite(const SCEV *S, const Loop *L, |
4308 | ScalarEvolution &SE) { |
4309 | bool IsPosBECond = false; |
4310 | Value *BECond = nullptr; |
4311 | if (BasicBlock *Latch = L->getLoopLatch()) { |
4312 | BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator()); |
4313 | if (BI && BI->isConditional()) { |
4314 | assert(BI->getSuccessor(0) != BI->getSuccessor(1) &&((BI->getSuccessor(0) != BI->getSuccessor(1) && "Both outgoing branches should not target same header!") ? static_cast <void> (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4315, __PRETTY_FUNCTION__)) |
4315 | "Both outgoing branches should not target same header!")((BI->getSuccessor(0) != BI->getSuccessor(1) && "Both outgoing branches should not target same header!") ? static_cast <void> (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4315, __PRETTY_FUNCTION__)); |
4316 | BECond = BI->getCondition(); |
4317 | IsPosBECond = BI->getSuccessor(0) == L->getHeader(); |
4318 | } else { |
4319 | return S; |
4320 | } |
4321 | } |
4322 | SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE); |
4323 | return Rewriter.visit(S); |
4324 | } |
4325 | |
4326 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
4327 | const SCEV *Result = Expr; |
4328 | bool InvariantF = SE.isLoopInvariant(Expr, L); |
4329 | |
4330 | if (!InvariantF) { |
4331 | Instruction *I = cast<Instruction>(Expr->getValue()); |
4332 | switch (I->getOpcode()) { |
4333 | case Instruction::Select: { |
4334 | SelectInst *SI = cast<SelectInst>(I); |
4335 | Optional<const SCEV *> Res = |
4336 | compareWithBackedgeCondition(SI->getCondition()); |
4337 | if (Res.hasValue()) { |
4338 | bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne(); |
4339 | Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue()); |
4340 | } |
4341 | break; |
4342 | } |
4343 | default: { |
4344 | Optional<const SCEV *> Res = compareWithBackedgeCondition(I); |
4345 | if (Res.hasValue()) |
4346 | Result = Res.getValue(); |
4347 | break; |
4348 | } |
4349 | } |
4350 | } |
4351 | return Result; |
4352 | } |
4353 | |
4354 | private: |
4355 | explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond, |
4356 | bool IsPosBECond, ScalarEvolution &SE) |
4357 | : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond), |
4358 | IsPositiveBECond(IsPosBECond) {} |
4359 | |
4360 | Optional<const SCEV *> compareWithBackedgeCondition(Value *IC); |
4361 | |
4362 | const Loop *L; |
4363 | /// Loop back condition. |
4364 | Value *BackedgeCond = nullptr; |
4365 | /// Set to true if loop back is on positive branch condition. |
4366 | bool IsPositiveBECond; |
4367 | }; |
4368 | |
4369 | Optional<const SCEV *> |
4370 | SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) { |
4371 | |
4372 | // If value matches the backedge condition for loop latch, |
4373 | // then return a constant evolution node based on loopback |
4374 | // branch taken. |
4375 | if (BackedgeCond == IC) |
4376 | return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext())) |
4377 | : SE.getZero(Type::getInt1Ty(SE.getContext())); |
4378 | return None; |
4379 | } |
4380 | |
4381 | class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> { |
4382 | public: |
4383 | static const SCEV *rewrite(const SCEV *S, const Loop *L, |
4384 | ScalarEvolution &SE) { |
4385 | SCEVShiftRewriter Rewriter(L, SE); |
4386 | const SCEV *Result = Rewriter.visit(S); |
4387 | return Rewriter.isValid() ? Result : SE.getCouldNotCompute(); |
4388 | } |
4389 | |
4390 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
4391 | // Only allow AddRecExprs for this loop. |
4392 | if (!SE.isLoopInvariant(Expr, L)) |
4393 | Valid = false; |
4394 | return Expr; |
4395 | } |
4396 | |
4397 | const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) { |
4398 | if (Expr->getLoop() == L && Expr->isAffine()) |
4399 | return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE)); |
4400 | Valid = false; |
4401 | return Expr; |
4402 | } |
4403 | |
4404 | bool isValid() { return Valid; } |
4405 | |
4406 | private: |
4407 | explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE) |
4408 | : SCEVRewriteVisitor(SE), L(L) {} |
4409 | |
4410 | const Loop *L; |
4411 | bool Valid = true; |
4412 | }; |
4413 | |
4414 | } // end anonymous namespace |
4415 | |
4416 | SCEV::NoWrapFlags |
4417 | ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) { |
4418 | if (!AR->isAffine()) |
4419 | return SCEV::FlagAnyWrap; |
4420 | |
4421 | using OBO = OverflowingBinaryOperator; |
4422 | |
4423 | SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap; |
4424 | |
4425 | if (!AR->hasNoSignedWrap()) { |
4426 | ConstantRange AddRecRange = getSignedRange(AR); |
4427 | ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this)); |
4428 | |
4429 | auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
4430 | Instruction::Add, IncRange, OBO::NoSignedWrap); |
4431 | if (NSWRegion.contains(AddRecRange)) |
4432 | Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW); |
4433 | } |
4434 | |
4435 | if (!AR->hasNoUnsignedWrap()) { |
4436 | ConstantRange AddRecRange = getUnsignedRange(AR); |
4437 | ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this)); |
4438 | |
4439 | auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion( |
4440 | Instruction::Add, IncRange, OBO::NoUnsignedWrap); |
4441 | if (NUWRegion.contains(AddRecRange)) |
4442 | Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW); |
4443 | } |
4444 | |
4445 | return Result; |
4446 | } |
4447 | |
4448 | namespace { |
4449 | |
4450 | /// Represents an abstract binary operation. This may exist as a |
4451 | /// normal instruction or constant expression, or may have been |
4452 | /// derived from an expression tree. |
4453 | struct BinaryOp { |
4454 | unsigned Opcode; |
4455 | Value *LHS; |
4456 | Value *RHS; |
4457 | bool IsNSW = false; |
4458 | bool IsNUW = false; |
4459 | |
4460 | /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or |
4461 | /// constant expression. |
4462 | Operator *Op = nullptr; |
4463 | |
4464 | explicit BinaryOp(Operator *Op) |
4465 | : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)), |
4466 | Op(Op) { |
4467 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) { |
4468 | IsNSW = OBO->hasNoSignedWrap(); |
4469 | IsNUW = OBO->hasNoUnsignedWrap(); |
4470 | } |
4471 | } |
4472 | |
4473 | explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false, |
4474 | bool IsNUW = false) |
4475 | : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {} |
4476 | }; |
4477 | |
4478 | } // end anonymous namespace |
4479 | |
4480 | /// Try to map \p V into a BinaryOp, and return \c None on failure. |
4481 | static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) { |
4482 | auto *Op = dyn_cast<Operator>(V); |
4483 | if (!Op) |
4484 | return None; |
4485 | |
4486 | // Implementation detail: all the cleverness here should happen without |
4487 | // creating new SCEV expressions -- our caller knowns tricks to avoid creating |
4488 | // SCEV expressions when possible, and we should not break that. |
4489 | |
4490 | switch (Op->getOpcode()) { |
4491 | case Instruction::Add: |
4492 | case Instruction::Sub: |
4493 | case Instruction::Mul: |
4494 | case Instruction::UDiv: |
4495 | case Instruction::URem: |
4496 | case Instruction::And: |
4497 | case Instruction::Or: |
4498 | case Instruction::AShr: |
4499 | case Instruction::Shl: |
4500 | return BinaryOp(Op); |
4501 | |
4502 | case Instruction::Xor: |
4503 | if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1))) |
4504 | // If the RHS of the xor is a signmask, then this is just an add. |
4505 | // Instcombine turns add of signmask into xor as a strength reduction step. |
4506 | if (RHSC->getValue().isSignMask()) |
4507 | return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1)); |
4508 | return BinaryOp(Op); |
4509 | |
4510 | case Instruction::LShr: |
4511 | // Turn logical shift right of a constant into a unsigned divide. |
4512 | if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) { |
4513 | uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth(); |
4514 | |
4515 | // If the shift count is not less than the bitwidth, the result of |
4516 | // the shift is undefined. Don't try to analyze it, because the |
4517 | // resolution chosen here may differ from the resolution chosen in |
4518 | // other parts of the compiler. |
4519 | if (SA->getValue().ult(BitWidth)) { |
4520 | Constant *X = |
4521 | ConstantInt::get(SA->getContext(), |
4522 | APInt::getOneBitSet(BitWidth, SA->getZExtValue())); |
4523 | return BinaryOp(Instruction::UDiv, Op->getOperand(0), X); |
4524 | } |
4525 | } |
4526 | return BinaryOp(Op); |
4527 | |
4528 | case Instruction::ExtractValue: { |
4529 | auto *EVI = cast<ExtractValueInst>(Op); |
4530 | if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0) |
4531 | break; |
4532 | |
4533 | auto *CI = dyn_cast<CallInst>(EVI->getAggregateOperand()); |
4534 | if (!CI) |
4535 | break; |
4536 | |
4537 | if (auto *F = CI->getCalledFunction()) |
4538 | switch (F->getIntrinsicID()) { |
4539 | case Intrinsic::sadd_with_overflow: |
4540 | case Intrinsic::uadd_with_overflow: |
4541 | if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT)) |
4542 | return BinaryOp(Instruction::Add, CI->getArgOperand(0), |
4543 | CI->getArgOperand(1)); |
4544 | |
4545 | // Now that we know that all uses of the arithmetic-result component of |
4546 | // CI are guarded by the overflow check, we can go ahead and pretend |
4547 | // that the arithmetic is non-overflowing. |
4548 | if (F->getIntrinsicID() == Intrinsic::sadd_with_overflow) |
4549 | return BinaryOp(Instruction::Add, CI->getArgOperand(0), |
4550 | CI->getArgOperand(1), /* IsNSW = */ true, |
4551 | /* IsNUW = */ false); |
4552 | else |
4553 | return BinaryOp(Instruction::Add, CI->getArgOperand(0), |
4554 | CI->getArgOperand(1), /* IsNSW = */ false, |
4555 | /* IsNUW*/ true); |
4556 | case Intrinsic::ssub_with_overflow: |
4557 | case Intrinsic::usub_with_overflow: |
4558 | if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT)) |
4559 | return BinaryOp(Instruction::Sub, CI->getArgOperand(0), |
4560 | CI->getArgOperand(1)); |
4561 | |
4562 | // The same reasoning as sadd/uadd above. |
4563 | if (F->getIntrinsicID() == Intrinsic::ssub_with_overflow) |
4564 | return BinaryOp(Instruction::Sub, CI->getArgOperand(0), |
4565 | CI->getArgOperand(1), /* IsNSW = */ true, |
4566 | /* IsNUW = */ false); |
4567 | else |
4568 | return BinaryOp(Instruction::Sub, CI->getArgOperand(0), |
4569 | CI->getArgOperand(1), /* IsNSW = */ false, |
4570 | /* IsNUW = */ true); |
4571 | case Intrinsic::smul_with_overflow: |
4572 | case Intrinsic::umul_with_overflow: |
4573 | return BinaryOp(Instruction::Mul, CI->getArgOperand(0), |
4574 | CI->getArgOperand(1)); |
4575 | default: |
4576 | break; |
4577 | } |
4578 | break; |
4579 | } |
4580 | |
4581 | default: |
4582 | break; |
4583 | } |
4584 | |
4585 | return None; |
4586 | } |
4587 | |
4588 | /// Helper function to createAddRecFromPHIWithCasts. We have a phi |
4589 | /// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via |
4590 | /// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the |
4591 | /// way. This function checks if \p Op, an operand of this SCEVAddExpr, |
4592 | /// follows one of the following patterns: |
4593 | /// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) |
4594 | /// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) |
4595 | /// If the SCEV expression of \p Op conforms with one of the expected patterns |
4596 | /// we return the type of the truncation operation, and indicate whether the |
4597 | /// truncated type should be treated as signed/unsigned by setting |
4598 | /// \p Signed to true/false, respectively. |
4599 | static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI, |
4600 | bool &Signed, ScalarEvolution &SE) { |
4601 | // The case where Op == SymbolicPHI (that is, with no type conversions on |
4602 | // the way) is handled by the regular add recurrence creating logic and |
4603 | // would have already been triggered in createAddRecForPHI. Reaching it here |
4604 | // means that createAddRecFromPHI had failed for this PHI before (e.g., |
4605 | // because one of the other operands of the SCEVAddExpr updating this PHI is |
4606 | // not invariant). |
4607 | // |
4608 | // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in |
4609 | // this case predicates that allow us to prove that Op == SymbolicPHI will |
4610 | // be added. |
4611 | if (Op == SymbolicPHI) |
4612 | return nullptr; |
4613 | |
4614 | unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType()); |
4615 | unsigned NewBits = SE.getTypeSizeInBits(Op->getType()); |
4616 | if (SourceBits != NewBits) |
4617 | return nullptr; |
4618 | |
4619 | const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op); |
4620 | const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op); |
4621 | if (!SExt && !ZExt) |
4622 | return nullptr; |
4623 | const SCEVTruncateExpr *Trunc = |
4624 | SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand()) |
4625 | : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand()); |
4626 | if (!Trunc) |
4627 | return nullptr; |
4628 | const SCEV *X = Trunc->getOperand(); |
4629 | if (X != SymbolicPHI) |
4630 | return nullptr; |
4631 | Signed = SExt != nullptr; |
4632 | return Trunc->getType(); |
4633 | } |
4634 | |
4635 | static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) { |
4636 | if (!PN->getType()->isIntegerTy()) |
4637 | return nullptr; |
4638 | const Loop *L = LI.getLoopFor(PN->getParent()); |
4639 | if (!L || L->getHeader() != PN->getParent()) |
4640 | return nullptr; |
4641 | return L; |
4642 | } |
4643 | |
4644 | // Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the |
4645 | // computation that updates the phi follows the following pattern: |
4646 | // (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum |
4647 | // which correspond to a phi->trunc->sext/zext->add->phi update chain. |
4648 | // If so, try to see if it can be rewritten as an AddRecExpr under some |
4649 | // Predicates. If successful, return them as a pair. Also cache the results |
4650 | // of the analysis. |
4651 | // |
4652 | // Example usage scenario: |
4653 | // Say the Rewriter is called for the following SCEV: |
4654 | // 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step) |
4655 | // where: |
4656 | // %X = phi i64 (%Start, %BEValue) |
4657 | // It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X), |
4658 | // and call this function with %SymbolicPHI = %X. |
4659 | // |
4660 | // The analysis will find that the value coming around the backedge has |
4661 | // the following SCEV: |
4662 | // BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step) |
4663 | // Upon concluding that this matches the desired pattern, the function |
4664 | // will return the pair {NewAddRec, SmallPredsVec} where: |
4665 | // NewAddRec = {%Start,+,%Step} |
4666 | // SmallPredsVec = {P1, P2, P3} as follows: |
4667 | // P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw> |
4668 | // P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64) |
4669 | // P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64) |
4670 | // The returned pair means that SymbolicPHI can be rewritten into NewAddRec |
4671 | // under the predicates {P1,P2,P3}. |
4672 | // This predicated rewrite will be cached in PredicatedSCEVRewrites: |
4673 | // PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)} |
4674 | // |
4675 | // TODO's: |
4676 | // |
4677 | // 1) Extend the Induction descriptor to also support inductions that involve |
4678 | // casts: When needed (namely, when we are called in the context of the |
4679 | // vectorizer induction analysis), a Set of cast instructions will be |
4680 | // populated by this method, and provided back to isInductionPHI. This is |
4681 | // needed to allow the vectorizer to properly record them to be ignored by |
4682 | // the cost model and to avoid vectorizing them (otherwise these casts, |
4683 | // which are redundant under the runtime overflow checks, will be |
4684 | // vectorized, which can be costly). |
4685 | // |
4686 | // 2) Support additional induction/PHISCEV patterns: We also want to support |
4687 | // inductions where the sext-trunc / zext-trunc operations (partly) occur |
4688 | // after the induction update operation (the induction increment): |
4689 | // |
4690 | // (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix) |
4691 | // which correspond to a phi->add->trunc->sext/zext->phi update chain. |
4692 | // |
4693 | // (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix) |
4694 | // which correspond to a phi->trunc->add->sext/zext->phi update chain. |
4695 | // |
4696 | // 3) Outline common code with createAddRecFromPHI to avoid duplication. |
4697 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
4698 | ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) { |
4699 | SmallVector<const SCEVPredicate *, 3> Predicates; |
4700 | |
4701 | // *** Part1: Analyze if we have a phi-with-cast pattern for which we can |
4702 | // return an AddRec expression under some predicate. |
4703 | |
4704 | auto *PN = cast<PHINode>(SymbolicPHI->getValue()); |
4705 | const Loop *L = isIntegerLoopHeaderPHI(PN, LI); |
4706 | assert(L && "Expecting an integer loop header phi")((L && "Expecting an integer loop header phi") ? static_cast <void> (0) : __assert_fail ("L && \"Expecting an integer loop header phi\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4706, __PRETTY_FUNCTION__)); |
4707 | |
4708 | // The loop may have multiple entrances or multiple exits; we can analyze |
4709 | // this phi as an addrec if it has a unique entry value and a unique |
4710 | // backedge value. |
4711 | Value *BEValueV = nullptr, *StartValueV = nullptr; |
4712 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
4713 | Value *V = PN->getIncomingValue(i); |
4714 | if (L->contains(PN->getIncomingBlock(i))) { |
4715 | if (!BEValueV) { |
4716 | BEValueV = V; |
4717 | } else if (BEValueV != V) { |
4718 | BEValueV = nullptr; |
4719 | break; |
4720 | } |
4721 | } else if (!StartValueV) { |
4722 | StartValueV = V; |
4723 | } else if (StartValueV != V) { |
4724 | StartValueV = nullptr; |
4725 | break; |
4726 | } |
4727 | } |
4728 | if (!BEValueV || !StartValueV) |
4729 | return None; |
4730 | |
4731 | const SCEV *BEValue = getSCEV(BEValueV); |
4732 | |
4733 | // If the value coming around the backedge is an add with the symbolic |
4734 | // value we just inserted, possibly with casts that we can ignore under |
4735 | // an appropriate runtime guard, then we found a simple induction variable! |
4736 | const auto *Add = dyn_cast<SCEVAddExpr>(BEValue); |
4737 | if (!Add) |
4738 | return None; |
4739 | |
4740 | // If there is a single occurrence of the symbolic value, possibly |
4741 | // casted, replace it with a recurrence. |
4742 | unsigned FoundIndex = Add->getNumOperands(); |
4743 | Type *TruncTy = nullptr; |
4744 | bool Signed; |
4745 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
4746 | if ((TruncTy = |
4747 | isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this))) |
4748 | if (FoundIndex == e) { |
4749 | FoundIndex = i; |
4750 | break; |
4751 | } |
4752 | |
4753 | if (FoundIndex == Add->getNumOperands()) |
4754 | return None; |
4755 | |
4756 | // Create an add with everything but the specified operand. |
4757 | SmallVector<const SCEV *, 8> Ops; |
4758 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
4759 | if (i != FoundIndex) |
4760 | Ops.push_back(Add->getOperand(i)); |
4761 | const SCEV *Accum = getAddExpr(Ops); |
4762 | |
4763 | // The runtime checks will not be valid if the step amount is |
4764 | // varying inside the loop. |
4765 | if (!isLoopInvariant(Accum, L)) |
4766 | return None; |
4767 | |
4768 | // *** Part2: Create the predicates |
4769 | |
4770 | // Analysis was successful: we have a phi-with-cast pattern for which we |
4771 | // can return an AddRec expression under the following predicates: |
4772 | // |
4773 | // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum) |
4774 | // fits within the truncated type (does not overflow) for i = 0 to n-1. |
4775 | // P2: An Equal predicate that guarantees that |
4776 | // Start = (Ext ix (Trunc iy (Start) to ix) to iy) |
4777 | // P3: An Equal predicate that guarantees that |
4778 | // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy) |
4779 | // |
4780 | // As we next prove, the above predicates guarantee that: |
4781 | // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy) |
4782 | // |
4783 | // |
4784 | // More formally, we want to prove that: |
4785 | // Expr(i+1) = Start + (i+1) * Accum |
4786 | // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum |
4787 | // |
4788 | // Given that: |
4789 | // 1) Expr(0) = Start |
4790 | // 2) Expr(1) = Start + Accum |
4791 | // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2 |
4792 | // 3) Induction hypothesis (step i): |
4793 | // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum |
4794 | // |
4795 | // Proof: |
4796 | // Expr(i+1) = |
4797 | // = Start + (i+1)*Accum |
4798 | // = (Start + i*Accum) + Accum |
4799 | // = Expr(i) + Accum |
4800 | // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum |
4801 | // :: from step i |
4802 | // |
4803 | // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum |
4804 | // |
4805 | // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) |
4806 | // + (Ext ix (Trunc iy (Accum) to ix) to iy) |
4807 | // + Accum :: from P3 |
4808 | // |
4809 | // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy) |
4810 | // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y) |
4811 | // |
4812 | // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum |
4813 | // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum |
4814 | // |
4815 | // By induction, the same applies to all iterations 1<=i<n: |
4816 | // |
4817 | |
4818 | // Create a truncated addrec for which we will add a no overflow check (P1). |
4819 | const SCEV *StartVal = getSCEV(StartValueV); |
4820 | const SCEV *PHISCEV = |
4821 | getAddRecExpr(getTruncateExpr(StartVal, TruncTy), |
4822 | getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap); |
4823 | |
4824 | // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr. |
4825 | // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV |
4826 | // will be constant. |
4827 | // |
4828 | // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't |
4829 | // add P1. |
4830 | if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) { |
4831 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags = |
4832 | Signed ? SCEVWrapPredicate::IncrementNSSW |
4833 | : SCEVWrapPredicate::IncrementNUSW; |
4834 | const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags); |
4835 | Predicates.push_back(AddRecPred); |
4836 | } |
4837 | |
4838 | // Create the Equal Predicates P2,P3: |
4839 | |
4840 | // It is possible that the predicates P2 and/or P3 are computable at |
4841 | // compile time due to StartVal and/or Accum being constants. |
4842 | // If either one is, then we can check that now and escape if either P2 |
4843 | // or P3 is false. |
4844 | |
4845 | // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy) |
4846 | // for each of StartVal and Accum |
4847 | auto getExtendedExpr = [&](const SCEV *Expr, |
4848 | bool CreateSignExtend) -> const SCEV * { |
4849 | assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")((isLoopInvariant(Expr, L) && "Expr is expected to be invariant" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4849, __PRETTY_FUNCTION__)); |
4850 | const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy); |
4851 | const SCEV *ExtendedExpr = |
4852 | CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType()) |
4853 | : getZeroExtendExpr(TruncatedExpr, Expr->getType()); |
4854 | return ExtendedExpr; |
4855 | }; |
4856 | |
4857 | // Given: |
4858 | // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy |
4859 | // = getExtendedExpr(Expr) |
4860 | // Determine whether the predicate P: Expr == ExtendedExpr |
4861 | // is known to be false at compile time |
4862 | auto PredIsKnownFalse = [&](const SCEV *Expr, |
4863 | const SCEV *ExtendedExpr) -> bool { |
4864 | return Expr != ExtendedExpr && |
4865 | isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr); |
4866 | }; |
4867 | |
4868 | const SCEV *StartExtended = getExtendedExpr(StartVal, Signed); |
4869 | if (PredIsKnownFalse(StartVal, StartExtended)) { |
4870 | LLVM_DEBUG(dbgs() << "P2 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "P2 is compile-time false\n" ;; } } while (false); |
4871 | return None; |
4872 | } |
4873 | |
4874 | // The Step is always Signed (because the overflow checks are either |
4875 | // NSSW or NUSW) |
4876 | const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true); |
4877 | if (PredIsKnownFalse(Accum, AccumExtended)) { |
4878 | LLVM_DEBUG(dbgs() << "P3 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "P3 is compile-time false\n" ;; } } while (false); |
4879 | return None; |
4880 | } |
4881 | |
4882 | auto AppendPredicate = [&](const SCEV *Expr, |
4883 | const SCEV *ExtendedExpr) -> void { |
4884 | if (Expr != ExtendedExpr && |
4885 | !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) { |
4886 | const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr); |
4887 | LLVM_DEBUG(dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "Added Predicate: " << *Pred; } } while (false); |
4888 | Predicates.push_back(Pred); |
4889 | } |
4890 | }; |
4891 | |
4892 | AppendPredicate(StartVal, StartExtended); |
4893 | AppendPredicate(Accum, AccumExtended); |
4894 | |
4895 | // *** Part3: Predicates are ready. Now go ahead and create the new addrec in |
4896 | // which the casts had been folded away. The caller can rewrite SymbolicPHI |
4897 | // into NewAR if it will also add the runtime overflow checks specified in |
4898 | // Predicates. |
4899 | auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap); |
4900 | |
4901 | std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite = |
4902 | std::make_pair(NewAR, Predicates); |
4903 | // Remember the result of the analysis for this SCEV at this locayyytion. |
4904 | PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite; |
4905 | return PredRewrite; |
4906 | } |
4907 | |
4908 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
4909 | ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) { |
4910 | auto *PN = cast<PHINode>(SymbolicPHI->getValue()); |
4911 | const Loop *L = isIntegerLoopHeaderPHI(PN, LI); |
4912 | if (!L) |
4913 | return None; |
4914 | |
4915 | // Check to see if we already analyzed this PHI. |
4916 | auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L}); |
4917 | if (I != PredicatedSCEVRewrites.end()) { |
4918 | std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite = |
4919 | I->second; |
4920 | // Analysis was done before and failed to create an AddRec: |
4921 | if (Rewrite.first == SymbolicPHI) |
4922 | return None; |
4923 | // Analysis was done before and succeeded to create an AddRec under |
4924 | // a predicate: |
4925 | assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")((isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4925, __PRETTY_FUNCTION__)); |
4926 | assert(!(Rewrite.second).empty() && "Expected to find Predicates")((!(Rewrite.second).empty() && "Expected to find Predicates" ) ? static_cast<void> (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4926, __PRETTY_FUNCTION__)); |
4927 | return Rewrite; |
4928 | } |
4929 | |
4930 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
4931 | Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI); |
4932 | |
4933 | // Record in the cache that the analysis failed |
4934 | if (!Rewrite) { |
4935 | SmallVector<const SCEVPredicate *, 3> Predicates; |
4936 | PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates}; |
4937 | return None; |
4938 | } |
4939 | |
4940 | return Rewrite; |
4941 | } |
4942 | |
4943 | // FIXME: This utility is currently required because the Rewriter currently |
4944 | // does not rewrite this expression: |
4945 | // {0, +, (sext ix (trunc iy to ix) to iy)} |
4946 | // into {0, +, %step}, |
4947 | // even when the following Equal predicate exists: |
4948 | // "%step == (sext ix (trunc iy to ix) to iy)". |
4949 | bool PredicatedScalarEvolution::areAddRecsEqualWithPreds( |
4950 | const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const { |
4951 | if (AR1 == AR2) |
4952 | return true; |
4953 | |
4954 | auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool { |
4955 | if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) && |
4956 | !Preds.implies(SE.getEqualPredicate(Expr2, Expr1))) |
4957 | return false; |
4958 | return true; |
4959 | }; |
4960 | |
4961 | if (!areExprsEqual(AR1->getStart(), AR2->getStart()) || |
4962 | !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE))) |
4963 | return false; |
4964 | return true; |
4965 | } |
4966 | |
4967 | /// A helper function for createAddRecFromPHI to handle simple cases. |
4968 | /// |
4969 | /// This function tries to find an AddRec expression for the simplest (yet most |
4970 | /// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)). |
4971 | /// If it fails, createAddRecFromPHI will use a more general, but slow, |
4972 | /// technique for finding the AddRec expression. |
4973 | const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN, |
4974 | Value *BEValueV, |
4975 | Value *StartValueV) { |
4976 | const Loop *L = LI.getLoopFor(PN->getParent()); |
4977 | assert(L && L->getHeader() == PN->getParent())((L && L->getHeader() == PN->getParent()) ? static_cast <void> (0) : __assert_fail ("L && L->getHeader() == PN->getParent()" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4977, __PRETTY_FUNCTION__)); |
4978 | assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> ( 0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 4978, __PRETTY_FUNCTION__)); |
4979 | |
4980 | auto BO = MatchBinaryOp(BEValueV, DT); |
4981 | if (!BO) |
4982 | return nullptr; |
4983 | |
4984 | if (BO->Opcode != Instruction::Add) |
4985 | return nullptr; |
4986 | |
4987 | const SCEV *Accum = nullptr; |
4988 | if (BO->LHS == PN && L->isLoopInvariant(BO->RHS)) |
4989 | Accum = getSCEV(BO->RHS); |
4990 | else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS)) |
4991 | Accum = getSCEV(BO->LHS); |
4992 | |
4993 | if (!Accum) |
4994 | return nullptr; |
4995 | |
4996 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
4997 | if (BO->IsNUW) |
4998 | Flags = setFlags(Flags, SCEV::FlagNUW); |
4999 | if (BO->IsNSW) |
5000 | Flags = setFlags(Flags, SCEV::FlagNSW); |
5001 | |
5002 | const SCEV *StartVal = getSCEV(StartValueV); |
5003 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); |
5004 | |
5005 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; |
5006 | |
5007 | // We can add Flags to the post-inc expression only if we |
5008 | // know that it is *undefined behavior* for BEValueV to |
5009 | // overflow. |
5010 | if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) |
5011 | if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L)) |
5012 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); |
5013 | |
5014 | return PHISCEV; |
5015 | } |
5016 | |
5017 | const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) { |
5018 | const Loop *L = LI.getLoopFor(PN->getParent()); |
5019 | if (!L || L->getHeader() != PN->getParent()) |
5020 | return nullptr; |
5021 | |
5022 | // The loop may have multiple entrances or multiple exits; we can analyze |
5023 | // this phi as an addrec if it has a unique entry value and a unique |
5024 | // backedge value. |
5025 | Value *BEValueV = nullptr, *StartValueV = nullptr; |
5026 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
5027 | Value *V = PN->getIncomingValue(i); |
5028 | if (L->contains(PN->getIncomingBlock(i))) { |
5029 | if (!BEValueV) { |
5030 | BEValueV = V; |
5031 | } else if (BEValueV != V) { |
5032 | BEValueV = nullptr; |
5033 | break; |
5034 | } |
5035 | } else if (!StartValueV) { |
5036 | StartValueV = V; |
5037 | } else if (StartValueV != V) { |
5038 | StartValueV = nullptr; |
5039 | break; |
5040 | } |
5041 | } |
5042 | if (!BEValueV || !StartValueV) |
5043 | return nullptr; |
5044 | |
5045 | assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?" ) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5046, __PRETTY_FUNCTION__)) |
5046 | "PHI node already processed?")((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?" ) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5046, __PRETTY_FUNCTION__)); |
5047 | |
5048 | // First, try to find AddRec expression without creating a fictituos symbolic |
5049 | // value for PN. |
5050 | if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV)) |
5051 | return S; |
5052 | |
5053 | // Handle PHI node value symbolically. |
5054 | const SCEV *SymbolicName = getUnknown(PN); |
5055 | ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName}); |
5056 | |
5057 | // Using this symbolic name for the PHI, analyze the value coming around |
5058 | // the back-edge. |
5059 | const SCEV *BEValue = getSCEV(BEValueV); |
5060 | |
5061 | // NOTE: If BEValue is loop invariant, we know that the PHI node just |
5062 | // has a special value for the first iteration of the loop. |
5063 | |
5064 | // If the value coming around the backedge is an add with the symbolic |
5065 | // value we just inserted, then we found a simple induction variable! |
5066 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) { |
5067 | // If there is a single occurrence of the symbolic value, replace it |
5068 | // with a recurrence. |
5069 | unsigned FoundIndex = Add->getNumOperands(); |
5070 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
5071 | if (Add->getOperand(i) == SymbolicName) |
5072 | if (FoundIndex == e) { |
5073 | FoundIndex = i; |
5074 | break; |
5075 | } |
5076 | |
5077 | if (FoundIndex != Add->getNumOperands()) { |
5078 | // Create an add with everything but the specified operand. |
5079 | SmallVector<const SCEV *, 8> Ops; |
5080 | for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i) |
5081 | if (i != FoundIndex) |
5082 | Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i), |
5083 | L, *this)); |
5084 | const SCEV *Accum = getAddExpr(Ops); |
5085 | |
5086 | // This is not a valid addrec if the step amount is varying each |
5087 | // loop iteration, but is not itself an addrec in this loop. |
5088 | if (isLoopInvariant(Accum, L) || |
5089 | (isa<SCEVAddRecExpr>(Accum) && |
5090 | cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) { |
5091 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
5092 | |
5093 | if (auto BO = MatchBinaryOp(BEValueV, DT)) { |
5094 | if (BO->Opcode == Instruction::Add && BO->LHS == PN) { |
5095 | if (BO->IsNUW) |
5096 | Flags = setFlags(Flags, SCEV::FlagNUW); |
5097 | if (BO->IsNSW) |
5098 | Flags = setFlags(Flags, SCEV::FlagNSW); |
5099 | } |
5100 | } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { |
5101 | // If the increment is an inbounds GEP, then we know the address |
5102 | // space cannot be wrapped around. We cannot make any guarantee |
5103 | // about signed or unsigned overflow because pointers are |
5104 | // unsigned but we may have a negative index from the base |
5105 | // pointer. We can guarantee that no unsigned wrap occurs if the |
5106 | // indices form a positive value. |
5107 | if (GEP->isInBounds() && GEP->getOperand(0) == PN) { |
5108 | Flags = setFlags(Flags, SCEV::FlagNW); |
5109 | |
5110 | const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); |
5111 | if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) |
5112 | Flags = setFlags(Flags, SCEV::FlagNUW); |
5113 | } |
5114 | |
5115 | // We cannot transfer nuw and nsw flags from subtraction |
5116 | // operations -- sub nuw X, Y is not the same as add nuw X, -Y |
5117 | // for instance. |
5118 | } |
5119 | |
5120 | const SCEV *StartVal = getSCEV(StartValueV); |
5121 | const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags); |
5122 | |
5123 | // Okay, for the entire analysis of this edge we assumed the PHI |
5124 | // to be symbolic. We now need to go back and purge all of the |
5125 | // entries for the scalars that use the symbolic expression. |
5126 | forgetSymbolicName(PN, SymbolicName); |
5127 | ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV; |
5128 | |
5129 | // We can add Flags to the post-inc expression only if we |
5130 | // know that it is *undefined behavior* for BEValueV to |
5131 | // overflow. |
5132 | if (auto *BEInst = dyn_cast<Instruction>(BEValueV)) |
5133 | if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L)) |
5134 | (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags); |
5135 | |
5136 | return PHISCEV; |
5137 | } |
5138 | } |
5139 | } else { |
5140 | // Otherwise, this could be a loop like this: |
5141 | // i = 0; for (j = 1; ..; ++j) { .... i = j; } |
5142 | // In this case, j = {1,+,1} and BEValue is j. |
5143 | // Because the other in-value of i (0) fits the evolution of BEValue |
5144 | // i really is an addrec evolution. |
5145 | // |
5146 | // We can generalize this saying that i is the shifted value of BEValue |
5147 | // by one iteration: |
5148 | // PHI(f(0), f({1,+,1})) --> f({0,+,1}) |
5149 | const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this); |
5150 | const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false); |
5151 | if (Shifted != getCouldNotCompute() && |
5152 | Start != getCouldNotCompute()) { |
5153 | const SCEV *StartVal = getSCEV(StartValueV); |
5154 | if (Start == StartVal) { |
5155 | // Okay, for the entire analysis of this edge we assumed the PHI |
5156 | // to be symbolic. We now need to go back and purge all of the |
5157 | // entries for the scalars that use the symbolic expression. |
5158 | forgetSymbolicName(PN, SymbolicName); |
5159 | ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted; |
5160 | return Shifted; |
5161 | } |
5162 | } |
5163 | } |
5164 | |
5165 | // Remove the temporary PHI node SCEV that has been inserted while intending |
5166 | // to create an AddRecExpr for this PHI node. We can not keep this temporary |
5167 | // as it will prevent later (possibly simpler) SCEV expressions to be added |
5168 | // to the ValueExprMap. |
5169 | eraseValueFromMap(PN); |
5170 | |
5171 | return nullptr; |
5172 | } |
5173 | |
5174 | // Checks if the SCEV S is available at BB. S is considered available at BB |
5175 | // if S can be materialized at BB without introducing a fault. |
5176 | static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S, |
5177 | BasicBlock *BB) { |
5178 | struct CheckAvailable { |
5179 | bool TraversalDone = false; |
5180 | bool Available = true; |
5181 | |
5182 | const Loop *L = nullptr; // The loop BB is in (can be nullptr) |
5183 | BasicBlock *BB = nullptr; |
5184 | DominatorTree &DT; |
5185 | |
5186 | CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT) |
5187 | : L(L), BB(BB), DT(DT) {} |
5188 | |
5189 | bool setUnavailable() { |
5190 | TraversalDone = true; |
5191 | Available = false; |
5192 | return false; |
5193 | } |
5194 | |
5195 | bool follow(const SCEV *S) { |
5196 | switch (S->getSCEVType()) { |
5197 | case scConstant: case scTruncate: case scZeroExtend: case scSignExtend: |
5198 | case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr: |
5199 | // These expressions are available if their operand(s) is/are. |
5200 | return true; |
5201 | |
5202 | case scAddRecExpr: { |
5203 | // We allow add recurrences that are on the loop BB is in, or some |
5204 | // outer loop. This guarantees availability because the value of the |
5205 | // add recurrence at BB is simply the "current" value of the induction |
5206 | // variable. We can relax this in the future; for instance an add |
5207 | // recurrence on a sibling dominating loop is also available at BB. |
5208 | const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop(); |
5209 | if (L && (ARLoop == L || ARLoop->contains(L))) |
5210 | return true; |
5211 | |
5212 | return setUnavailable(); |
5213 | } |
5214 | |
5215 | case scUnknown: { |
5216 | // For SCEVUnknown, we check for simple dominance. |
5217 | const auto *SU = cast<SCEVUnknown>(S); |
5218 | Value *V = SU->getValue(); |
5219 | |
5220 | if (isa<Argument>(V)) |
5221 | return false; |
5222 | |
5223 | if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB)) |
5224 | return false; |
5225 | |
5226 | return setUnavailable(); |
5227 | } |
5228 | |
5229 | case scUDivExpr: |
5230 | case scCouldNotCompute: |
5231 | // We do not try to smart about these at all. |
5232 | return setUnavailable(); |
5233 | } |
5234 | llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5234); |
5235 | } |
5236 | |
5237 | bool isDone() { return TraversalDone; } |
5238 | }; |
5239 | |
5240 | CheckAvailable CA(L, BB, DT); |
5241 | SCEVTraversal<CheckAvailable> ST(CA); |
5242 | |
5243 | ST.visitAll(S); |
5244 | return CA.Available; |
5245 | } |
5246 | |
5247 | // Try to match a control flow sequence that branches out at BI and merges back |
5248 | // at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful |
5249 | // match. |
5250 | static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge, |
5251 | Value *&C, Value *&LHS, Value *&RHS) { |
5252 | C = BI->getCondition(); |
5253 | |
5254 | BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0)); |
5255 | BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1)); |
5256 | |
5257 | if (!LeftEdge.isSingleEdge()) |
5258 | return false; |
5259 | |
5260 | assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")((RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()" ) ? static_cast<void> (0) : __assert_fail ("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5260, __PRETTY_FUNCTION__)); |
5261 | |
5262 | Use &LeftUse = Merge->getOperandUse(0); |
5263 | Use &RightUse = Merge->getOperandUse(1); |
5264 | |
5265 | if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) { |
5266 | LHS = LeftUse; |
5267 | RHS = RightUse; |
5268 | return true; |
5269 | } |
5270 | |
5271 | if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) { |
5272 | LHS = RightUse; |
5273 | RHS = LeftUse; |
5274 | return true; |
5275 | } |
5276 | |
5277 | return false; |
5278 | } |
5279 | |
5280 | const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) { |
5281 | auto IsReachable = |
5282 | [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); }; |
5283 | if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) { |
5284 | const Loop *L = LI.getLoopFor(PN->getParent()); |
5285 | |
5286 | // We don't want to break LCSSA, even in a SCEV expression tree. |
5287 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
5288 | if (LI.getLoopFor(PN->getIncomingBlock(i)) != L) |
5289 | return nullptr; |
5290 | |
5291 | // Try to match |
5292 | // |
5293 | // br %cond, label %left, label %right |
5294 | // left: |
5295 | // br label %merge |
5296 | // right: |
5297 | // br label %merge |
5298 | // merge: |
5299 | // V = phi [ %x, %left ], [ %y, %right ] |
5300 | // |
5301 | // as "select %cond, %x, %y" |
5302 | |
5303 | BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock(); |
5304 | assert(IDom && "At least the entry block should dominate PN")((IDom && "At least the entry block should dominate PN" ) ? static_cast<void> (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5304, __PRETTY_FUNCTION__)); |
5305 | |
5306 | auto *BI = dyn_cast<BranchInst>(IDom->getTerminator()); |
5307 | Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr; |
5308 | |
5309 | if (BI && BI->isConditional() && |
5310 | BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) && |
5311 | IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) && |
5312 | IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent())) |
5313 | return createNodeForSelectOrPHI(PN, Cond, LHS, RHS); |
5314 | } |
5315 | |
5316 | return nullptr; |
5317 | } |
5318 | |
5319 | const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { |
5320 | if (const SCEV *S = createAddRecFromPHI(PN)) |
5321 | return S; |
5322 | |
5323 | if (const SCEV *S = createNodeFromSelectLikePHI(PN)) |
5324 | return S; |
5325 | |
5326 | // If the PHI has a single incoming value, follow that value, unless the |
5327 | // PHI's incoming blocks are in a different loop, in which case doing so |
5328 | // risks breaking LCSSA form. Instcombine would normally zap these, but |
5329 | // it doesn't have DominatorTree information, so it may miss cases. |
5330 | if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC})) |
5331 | if (LI.replacementPreservesLCSSAForm(PN, V)) |
5332 | return getSCEV(V); |
5333 | |
5334 | // If it's not a loop phi, we can't handle it yet. |
5335 | return getUnknown(PN); |
5336 | } |
5337 | |
5338 | const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I, |
5339 | Value *Cond, |
5340 | Value *TrueVal, |
5341 | Value *FalseVal) { |
5342 | // Handle "constant" branch or select. This can occur for instance when a |
5343 | // loop pass transforms an inner loop and moves on to process the outer loop. |
5344 | if (auto *CI = dyn_cast<ConstantInt>(Cond)) |
5345 | return getSCEV(CI->isOne() ? TrueVal : FalseVal); |
5346 | |
5347 | // Try to match some simple smax or umax patterns. |
5348 | auto *ICI = dyn_cast<ICmpInst>(Cond); |
5349 | if (!ICI) |
5350 | return getUnknown(I); |
5351 | |
5352 | Value *LHS = ICI->getOperand(0); |
5353 | Value *RHS = ICI->getOperand(1); |
5354 | |
5355 | switch (ICI->getPredicate()) { |
5356 | case ICmpInst::ICMP_SLT: |
5357 | case ICmpInst::ICMP_SLE: |
5358 | std::swap(LHS, RHS); |
5359 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
5360 | case ICmpInst::ICMP_SGT: |
5361 | case ICmpInst::ICMP_SGE: |
5362 | // a >s b ? a+x : b+x -> smax(a, b)+x |
5363 | // a >s b ? b+x : a+x -> smin(a, b)+x |
5364 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { |
5365 | const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType()); |
5366 | const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType()); |
5367 | const SCEV *LA = getSCEV(TrueVal); |
5368 | const SCEV *RA = getSCEV(FalseVal); |
5369 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
5370 | const SCEV *RDiff = getMinusSCEV(RA, RS); |
5371 | if (LDiff == RDiff) |
5372 | return getAddExpr(getSMaxExpr(LS, RS), LDiff); |
5373 | LDiff = getMinusSCEV(LA, RS); |
5374 | RDiff = getMinusSCEV(RA, LS); |
5375 | if (LDiff == RDiff) |
5376 | return getAddExpr(getSMinExpr(LS, RS), LDiff); |
5377 | } |
5378 | break; |
5379 | case ICmpInst::ICMP_ULT: |
5380 | case ICmpInst::ICMP_ULE: |
5381 | std::swap(LHS, RHS); |
5382 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
5383 | case ICmpInst::ICMP_UGT: |
5384 | case ICmpInst::ICMP_UGE: |
5385 | // a >u b ? a+x : b+x -> umax(a, b)+x |
5386 | // a >u b ? b+x : a+x -> umin(a, b)+x |
5387 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) { |
5388 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); |
5389 | const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType()); |
5390 | const SCEV *LA = getSCEV(TrueVal); |
5391 | const SCEV *RA = getSCEV(FalseVal); |
5392 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
5393 | const SCEV *RDiff = getMinusSCEV(RA, RS); |
5394 | if (LDiff == RDiff) |
5395 | return getAddExpr(getUMaxExpr(LS, RS), LDiff); |
5396 | LDiff = getMinusSCEV(LA, RS); |
5397 | RDiff = getMinusSCEV(RA, LS); |
5398 | if (LDiff == RDiff) |
5399 | return getAddExpr(getUMinExpr(LS, RS), LDiff); |
5400 | } |
5401 | break; |
5402 | case ICmpInst::ICMP_NE: |
5403 | // n != 0 ? n+x : 1+x -> umax(n, 1)+x |
5404 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && |
5405 | isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { |
5406 | const SCEV *One = getOne(I->getType()); |
5407 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); |
5408 | const SCEV *LA = getSCEV(TrueVal); |
5409 | const SCEV *RA = getSCEV(FalseVal); |
5410 | const SCEV *LDiff = getMinusSCEV(LA, LS); |
5411 | const SCEV *RDiff = getMinusSCEV(RA, One); |
5412 | if (LDiff == RDiff) |
5413 | return getAddExpr(getUMaxExpr(One, LS), LDiff); |
5414 | } |
5415 | break; |
5416 | case ICmpInst::ICMP_EQ: |
5417 | // n == 0 ? 1+x : n+x -> umax(n, 1)+x |
5418 | if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) && |
5419 | isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) { |
5420 | const SCEV *One = getOne(I->getType()); |
5421 | const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType()); |
5422 | const SCEV *LA = getSCEV(TrueVal); |
5423 | const SCEV *RA = getSCEV(FalseVal); |
5424 | const SCEV *LDiff = getMinusSCEV(LA, One); |
5425 | const SCEV *RDiff = getMinusSCEV(RA, LS); |
5426 | if (LDiff == RDiff) |
5427 | return getAddExpr(getUMaxExpr(One, LS), LDiff); |
5428 | } |
5429 | break; |
5430 | default: |
5431 | break; |
5432 | } |
5433 | |
5434 | return getUnknown(I); |
5435 | } |
5436 | |
5437 | /// Expand GEP instructions into add and multiply operations. This allows them |
5438 | /// to be analyzed by regular SCEV code. |
5439 | const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) { |
5440 | // Don't attempt to analyze GEPs over unsized objects. |
5441 | if (!GEP->getSourceElementType()->isSized()) |
5442 | return getUnknown(GEP); |
5443 | |
5444 | SmallVector<const SCEV *, 4> IndexExprs; |
5445 | for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index) |
5446 | IndexExprs.push_back(getSCEV(*Index)); |
5447 | return getGEPExpr(GEP, IndexExprs); |
5448 | } |
5449 | |
5450 | uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) { |
5451 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) |
5452 | return C->getAPInt().countTrailingZeros(); |
5453 | |
5454 | if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S)) |
5455 | return std::min(GetMinTrailingZeros(T->getOperand()), |
5456 | (uint32_t)getTypeSizeInBits(T->getType())); |
5457 | |
5458 | if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) { |
5459 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); |
5460 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) |
5461 | ? getTypeSizeInBits(E->getType()) |
5462 | : OpRes; |
5463 | } |
5464 | |
5465 | if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) { |
5466 | uint32_t OpRes = GetMinTrailingZeros(E->getOperand()); |
5467 | return OpRes == getTypeSizeInBits(E->getOperand()->getType()) |
5468 | ? getTypeSizeInBits(E->getType()) |
5469 | : OpRes; |
5470 | } |
5471 | |
5472 | if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) { |
5473 | // The result is the min of all operands results. |
5474 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); |
5475 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) |
5476 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); |
5477 | return MinOpRes; |
5478 | } |
5479 | |
5480 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) { |
5481 | // The result is the sum of all operands results. |
5482 | uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0)); |
5483 | uint32_t BitWidth = getTypeSizeInBits(M->getType()); |
5484 | for (unsigned i = 1, e = M->getNumOperands(); |
5485 | SumOpRes != BitWidth && i != e; ++i) |
5486 | SumOpRes = |
5487 | std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth); |
5488 | return SumOpRes; |
5489 | } |
5490 | |
5491 | if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) { |
5492 | // The result is the min of all operands results. |
5493 | uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0)); |
5494 | for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i) |
5495 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i))); |
5496 | return MinOpRes; |
5497 | } |
5498 | |
5499 | if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) { |
5500 | // The result is the min of all operands results. |
5501 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); |
5502 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) |
5503 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); |
5504 | return MinOpRes; |
5505 | } |
5506 | |
5507 | if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) { |
5508 | // The result is the min of all operands results. |
5509 | uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0)); |
5510 | for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i) |
5511 | MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i))); |
5512 | return MinOpRes; |
5513 | } |
5514 | |
5515 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
5516 | // For a SCEVUnknown, ask ValueTracking. |
5517 | KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT); |
5518 | return Known.countMinTrailingZeros(); |
5519 | } |
5520 | |
5521 | // SCEVUDivExpr |
5522 | return 0; |
5523 | } |
5524 | |
5525 | uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) { |
5526 | auto I = MinTrailingZerosCache.find(S); |
5527 | if (I != MinTrailingZerosCache.end()) |
5528 | return I->second; |
5529 | |
5530 | uint32_t Result = GetMinTrailingZerosImpl(S); |
5531 | auto InsertPair = MinTrailingZerosCache.insert({S, Result}); |
5532 | assert(InsertPair.second && "Should insert a new key")((InsertPair.second && "Should insert a new key") ? static_cast <void> (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5532, __PRETTY_FUNCTION__)); |
5533 | return InsertPair.first->second; |
5534 | } |
5535 | |
5536 | /// Helper method to assign a range to V from metadata present in the IR. |
5537 | static Optional<ConstantRange> GetRangeFromMetadata(Value *V) { |
5538 | if (Instruction *I = dyn_cast<Instruction>(V)) |
5539 | if (MDNode *MD = I->getMetadata(LLVMContext::MD_range)) |
5540 | return getConstantRangeFromMetadata(*MD); |
5541 | |
5542 | return None; |
5543 | } |
5544 | |
5545 | /// Determine the range for a particular SCEV. If SignHint is |
5546 | /// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges |
5547 | /// with a "cleaner" unsigned (resp. signed) representation. |
5548 | const ConstantRange & |
5549 | ScalarEvolution::getRangeRef(const SCEV *S, |
5550 | ScalarEvolution::RangeSignHint SignHint) { |
5551 | DenseMap<const SCEV *, ConstantRange> &Cache = |
5552 | SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges |
5553 | : SignedRanges; |
5554 | |
5555 | // See if we've computed this range already. |
5556 | DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S); |
5557 | if (I != Cache.end()) |
5558 | return I->second; |
5559 | |
5560 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) |
5561 | return setRange(C, SignHint, ConstantRange(C->getAPInt())); |
5562 | |
5563 | unsigned BitWidth = getTypeSizeInBits(S->getType()); |
5564 | ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true); |
5565 | |
5566 | // If the value has known zeros, the maximum value will have those known zeros |
5567 | // as well. |
5568 | uint32_t TZ = GetMinTrailingZeros(S); |
5569 | if (TZ != 0) { |
5570 | if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) |
5571 | ConservativeResult = |
5572 | ConstantRange(APInt::getMinValue(BitWidth), |
5573 | APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1); |
5574 | else |
5575 | ConservativeResult = ConstantRange( |
5576 | APInt::getSignedMinValue(BitWidth), |
5577 | APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1); |
5578 | } |
5579 | |
5580 | if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { |
5581 | ConstantRange X = getRangeRef(Add->getOperand(0), SignHint); |
5582 | for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i) |
5583 | X = X.add(getRangeRef(Add->getOperand(i), SignHint)); |
5584 | return setRange(Add, SignHint, ConservativeResult.intersectWith(X)); |
5585 | } |
5586 | |
5587 | if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) { |
5588 | ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint); |
5589 | for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i) |
5590 | X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint)); |
5591 | return setRange(Mul, SignHint, ConservativeResult.intersectWith(X)); |
5592 | } |
5593 | |
5594 | if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) { |
5595 | ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint); |
5596 | for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i) |
5597 | X = X.smax(getRangeRef(SMax->getOperand(i), SignHint)); |
5598 | return setRange(SMax, SignHint, ConservativeResult.intersectWith(X)); |
5599 | } |
5600 | |
5601 | if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) { |
5602 | ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint); |
5603 | for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i) |
5604 | X = X.umax(getRangeRef(UMax->getOperand(i), SignHint)); |
5605 | return setRange(UMax, SignHint, ConservativeResult.intersectWith(X)); |
5606 | } |
5607 | |
5608 | if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) { |
5609 | ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint); |
5610 | ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint); |
5611 | return setRange(UDiv, SignHint, |
5612 | ConservativeResult.intersectWith(X.udiv(Y))); |
5613 | } |
5614 | |
5615 | if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) { |
5616 | ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint); |
5617 | return setRange(ZExt, SignHint, |
5618 | ConservativeResult.intersectWith(X.zeroExtend(BitWidth))); |
5619 | } |
5620 | |
5621 | if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) { |
5622 | ConstantRange X = getRangeRef(SExt->getOperand(), SignHint); |
5623 | return setRange(SExt, SignHint, |
5624 | ConservativeResult.intersectWith(X.signExtend(BitWidth))); |
5625 | } |
5626 | |
5627 | if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) { |
5628 | ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint); |
5629 | return setRange(Trunc, SignHint, |
5630 | ConservativeResult.intersectWith(X.truncate(BitWidth))); |
5631 | } |
5632 | |
5633 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) { |
5634 | // If there's no unsigned wrap, the value will never be less than its |
5635 | // initial value. |
5636 | if (AddRec->hasNoUnsignedWrap()) |
5637 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart())) |
5638 | if (!C->getValue()->isZero()) |
5639 | ConservativeResult = ConservativeResult.intersectWith( |
5640 | ConstantRange(C->getAPInt(), APInt(BitWidth, 0))); |
5641 | |
5642 | // If there's no signed wrap, and all the operands have the same sign or |
5643 | // zero, the value won't ever change sign. |
5644 | if (AddRec->hasNoSignedWrap()) { |
5645 | bool AllNonNeg = true; |
5646 | bool AllNonPos = true; |
5647 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) { |
5648 | if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false; |
5649 | if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false; |
5650 | } |
5651 | if (AllNonNeg) |
5652 | ConservativeResult = ConservativeResult.intersectWith( |
5653 | ConstantRange(APInt(BitWidth, 0), |
5654 | APInt::getSignedMinValue(BitWidth))); |
5655 | else if (AllNonPos) |
5656 | ConservativeResult = ConservativeResult.intersectWith( |
5657 | ConstantRange(APInt::getSignedMinValue(BitWidth), |
5658 | APInt(BitWidth, 1))); |
5659 | } |
5660 | |
5661 | // TODO: non-affine addrec |
5662 | if (AddRec->isAffine()) { |
5663 | const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop()); |
5664 | if (!isa<SCEVCouldNotCompute>(MaxBECount) && |
5665 | getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) { |
5666 | auto RangeFromAffine = getRangeForAffineAR( |
5667 | AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount, |
5668 | BitWidth); |
5669 | if (!RangeFromAffine.isFullSet()) |
5670 | ConservativeResult = |
5671 | ConservativeResult.intersectWith(RangeFromAffine); |
5672 | |
5673 | auto RangeFromFactoring = getRangeViaFactoring( |
5674 | AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount, |
5675 | BitWidth); |
5676 | if (!RangeFromFactoring.isFullSet()) |
5677 | ConservativeResult = |
5678 | ConservativeResult.intersectWith(RangeFromFactoring); |
5679 | } |
5680 | } |
5681 | |
5682 | return setRange(AddRec, SignHint, std::move(ConservativeResult)); |
5683 | } |
5684 | |
5685 | if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) { |
5686 | // Check if the IR explicitly contains !range metadata. |
5687 | Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue()); |
5688 | if (MDRange.hasValue()) |
5689 | ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue()); |
5690 | |
5691 | // Split here to avoid paying the compile-time cost of calling both |
5692 | // computeKnownBits and ComputeNumSignBits. This restriction can be lifted |
5693 | // if needed. |
5694 | const DataLayout &DL = getDataLayout(); |
5695 | if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) { |
5696 | // For a SCEVUnknown, ask ValueTracking. |
5697 | KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT); |
5698 | if (Known.One != ~Known.Zero + 1) |
5699 | ConservativeResult = |
5700 | ConservativeResult.intersectWith(ConstantRange(Known.One, |
5701 | ~Known.Zero + 1)); |
5702 | } else { |
5703 | assert(SignHint == ScalarEvolution::HINT_RANGE_SIGNED &&((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!" ) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5704, __PRETTY_FUNCTION__)) |
5704 | "generalize as needed!")((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!" ) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5704, __PRETTY_FUNCTION__)); |
5705 | unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT); |
5706 | if (NS > 1) |
5707 | ConservativeResult = ConservativeResult.intersectWith( |
5708 | ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1), |
5709 | APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1)); |
5710 | } |
5711 | |
5712 | // A range of Phi is a subset of union of all ranges of its input. |
5713 | if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) { |
5714 | // Make sure that we do not run over cycled Phis. |
5715 | if (PendingPhiRanges.insert(Phi).second) { |
5716 | ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false); |
5717 | for (auto &Op : Phi->operands()) { |
5718 | auto OpRange = getRangeRef(getSCEV(Op), SignHint); |
5719 | RangeFromOps = RangeFromOps.unionWith(OpRange); |
5720 | // No point to continue if we already have a full set. |
5721 | if (RangeFromOps.isFullSet()) |
5722 | break; |
5723 | } |
5724 | ConservativeResult = ConservativeResult.intersectWith(RangeFromOps); |
5725 | bool Erased = PendingPhiRanges.erase(Phi); |
5726 | assert(Erased && "Failed to erase Phi properly?")((Erased && "Failed to erase Phi properly?") ? static_cast <void> (0) : __assert_fail ("Erased && \"Failed to erase Phi properly?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5726, __PRETTY_FUNCTION__)); |
5727 | (void) Erased; |
5728 | } |
5729 | } |
5730 | |
5731 | return setRange(U, SignHint, std::move(ConservativeResult)); |
5732 | } |
5733 | |
5734 | return setRange(S, SignHint, std::move(ConservativeResult)); |
5735 | } |
5736 | |
5737 | // Given a StartRange, Step and MaxBECount for an expression compute a range of |
5738 | // values that the expression can take. Initially, the expression has a value |
5739 | // from StartRange and then is changed by Step up to MaxBECount times. Signed |
5740 | // argument defines if we treat Step as signed or unsigned. |
5741 | static ConstantRange getRangeForAffineARHelper(APInt Step, |
5742 | const ConstantRange &StartRange, |
5743 | const APInt &MaxBECount, |
5744 | unsigned BitWidth, bool Signed) { |
5745 | // If either Step or MaxBECount is 0, then the expression won't change, and we |
5746 | // just need to return the initial range. |
5747 | if (Step == 0 || MaxBECount == 0) |
5748 | return StartRange; |
5749 | |
5750 | // If we don't know anything about the initial value (i.e. StartRange is |
5751 | // FullRange), then we don't know anything about the final range either. |
5752 | // Return FullRange. |
5753 | if (StartRange.isFullSet()) |
5754 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5755 | |
5756 | // If Step is signed and negative, then we use its absolute value, but we also |
5757 | // note that we're moving in the opposite direction. |
5758 | bool Descending = Signed && Step.isNegative(); |
5759 | |
5760 | if (Signed) |
5761 | // This is correct even for INT_SMIN. Let's look at i8 to illustrate this: |
5762 | // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128. |
5763 | // This equations hold true due to the well-defined wrap-around behavior of |
5764 | // APInt. |
5765 | Step = Step.abs(); |
5766 | |
5767 | // Check if Offset is more than full span of BitWidth. If it is, the |
5768 | // expression is guaranteed to overflow. |
5769 | if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount)) |
5770 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5771 | |
5772 | // Offset is by how much the expression can change. Checks above guarantee no |
5773 | // overflow here. |
5774 | APInt Offset = Step * MaxBECount; |
5775 | |
5776 | // Minimum value of the final range will match the minimal value of StartRange |
5777 | // if the expression is increasing and will be decreased by Offset otherwise. |
5778 | // Maximum value of the final range will match the maximal value of StartRange |
5779 | // if the expression is decreasing and will be increased by Offset otherwise. |
5780 | APInt StartLower = StartRange.getLower(); |
5781 | APInt StartUpper = StartRange.getUpper() - 1; |
5782 | APInt MovedBoundary = Descending ? (StartLower - std::move(Offset)) |
5783 | : (StartUpper + std::move(Offset)); |
5784 | |
5785 | // It's possible that the new minimum/maximum value will fall into the initial |
5786 | // range (due to wrap around). This means that the expression can take any |
5787 | // value in this bitwidth, and we have to return full range. |
5788 | if (StartRange.contains(MovedBoundary)) |
5789 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5790 | |
5791 | APInt NewLower = |
5792 | Descending ? std::move(MovedBoundary) : std::move(StartLower); |
5793 | APInt NewUpper = |
5794 | Descending ? std::move(StartUpper) : std::move(MovedBoundary); |
5795 | NewUpper += 1; |
5796 | |
5797 | // If we end up with full range, return a proper full range. |
5798 | if (NewLower == NewUpper) |
5799 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5800 | |
5801 | // No overflow detected, return [StartLower, StartUpper + Offset + 1) range. |
5802 | return ConstantRange(std::move(NewLower), std::move(NewUpper)); |
5803 | } |
5804 | |
5805 | ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start, |
5806 | const SCEV *Step, |
5807 | const SCEV *MaxBECount, |
5808 | unsigned BitWidth) { |
5809 | assert(!isa<SCEVCouldNotCompute>(MaxBECount) &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits (MaxBECount->getType()) <= BitWidth && "Precondition!" ) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5811, __PRETTY_FUNCTION__)) |
5810 | getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits (MaxBECount->getType()) <= BitWidth && "Precondition!" ) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5811, __PRETTY_FUNCTION__)) |
5811 | "Precondition!")((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits (MaxBECount->getType()) <= BitWidth && "Precondition!" ) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5811, __PRETTY_FUNCTION__)); |
5812 | |
5813 | MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType()); |
5814 | APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount); |
5815 | |
5816 | // First, consider step signed. |
5817 | ConstantRange StartSRange = getSignedRange(Start); |
5818 | ConstantRange StepSRange = getSignedRange(Step); |
5819 | |
5820 | // If Step can be both positive and negative, we need to find ranges for the |
5821 | // maximum absolute step values in both directions and union them. |
5822 | ConstantRange SR = |
5823 | getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange, |
5824 | MaxBECountValue, BitWidth, /* Signed = */ true); |
5825 | SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(), |
5826 | StartSRange, MaxBECountValue, |
5827 | BitWidth, /* Signed = */ true)); |
5828 | |
5829 | // Next, consider step unsigned. |
5830 | ConstantRange UR = getRangeForAffineARHelper( |
5831 | getUnsignedRangeMax(Step), getUnsignedRange(Start), |
5832 | MaxBECountValue, BitWidth, /* Signed = */ false); |
5833 | |
5834 | // Finally, intersect signed and unsigned ranges. |
5835 | return SR.intersectWith(UR); |
5836 | } |
5837 | |
5838 | ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start, |
5839 | const SCEV *Step, |
5840 | const SCEV *MaxBECount, |
5841 | unsigned BitWidth) { |
5842 | // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q}) |
5843 | // == RangeOf({A,+,P}) union RangeOf({B,+,Q}) |
5844 | |
5845 | struct SelectPattern { |
5846 | Value *Condition = nullptr; |
5847 | APInt TrueValue; |
5848 | APInt FalseValue; |
5849 | |
5850 | explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth, |
5851 | const SCEV *S) { |
5852 | Optional<unsigned> CastOp; |
5853 | APInt Offset(BitWidth, 0); |
5854 | |
5855 | assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&((SE.getTypeSizeInBits(S->getType()) == BitWidth && "Should be!") ? static_cast<void> (0) : __assert_fail ( "SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5856, __PRETTY_FUNCTION__)) |
5856 | "Should be!")((SE.getTypeSizeInBits(S->getType()) == BitWidth && "Should be!") ? static_cast<void> (0) : __assert_fail ( "SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5856, __PRETTY_FUNCTION__)); |
5857 | |
5858 | // Peel off a constant offset: |
5859 | if (auto *SA = dyn_cast<SCEVAddExpr>(S)) { |
5860 | // In the future we could consider being smarter here and handle |
5861 | // {Start+Step,+,Step} too. |
5862 | if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0))) |
5863 | return; |
5864 | |
5865 | Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt(); |
5866 | S = SA->getOperand(1); |
5867 | } |
5868 | |
5869 | // Peel off a cast operation |
5870 | if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) { |
5871 | CastOp = SCast->getSCEVType(); |
5872 | S = SCast->getOperand(); |
5873 | } |
5874 | |
5875 | using namespace llvm::PatternMatch; |
5876 | |
5877 | auto *SU = dyn_cast<SCEVUnknown>(S); |
5878 | const APInt *TrueVal, *FalseVal; |
5879 | if (!SU || |
5880 | !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal), |
5881 | m_APInt(FalseVal)))) { |
5882 | Condition = nullptr; |
5883 | return; |
5884 | } |
5885 | |
5886 | TrueValue = *TrueVal; |
5887 | FalseValue = *FalseVal; |
5888 | |
5889 | // Re-apply the cast we peeled off earlier |
5890 | if (CastOp.hasValue()) |
5891 | switch (*CastOp) { |
5892 | default: |
5893 | llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 5893); |
5894 | |
5895 | case scTruncate: |
5896 | TrueValue = TrueValue.trunc(BitWidth); |
5897 | FalseValue = FalseValue.trunc(BitWidth); |
5898 | break; |
5899 | case scZeroExtend: |
5900 | TrueValue = TrueValue.zext(BitWidth); |
5901 | FalseValue = FalseValue.zext(BitWidth); |
5902 | break; |
5903 | case scSignExtend: |
5904 | TrueValue = TrueValue.sext(BitWidth); |
5905 | FalseValue = FalseValue.sext(BitWidth); |
5906 | break; |
5907 | } |
5908 | |
5909 | // Re-apply the constant offset we peeled off earlier |
5910 | TrueValue += Offset; |
5911 | FalseValue += Offset; |
5912 | } |
5913 | |
5914 | bool isRecognized() { return Condition != nullptr; } |
5915 | }; |
5916 | |
5917 | SelectPattern StartPattern(*this, BitWidth, Start); |
5918 | if (!StartPattern.isRecognized()) |
5919 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5920 | |
5921 | SelectPattern StepPattern(*this, BitWidth, Step); |
5922 | if (!StepPattern.isRecognized()) |
5923 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5924 | |
5925 | if (StartPattern.Condition != StepPattern.Condition) { |
5926 | // We don't handle this case today; but we could, by considering four |
5927 | // possibilities below instead of two. I'm not sure if there are cases where |
5928 | // that will help over what getRange already does, though. |
5929 | return ConstantRange(BitWidth, /* isFullSet = */ true); |
5930 | } |
5931 | |
5932 | // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to |
5933 | // construct arbitrary general SCEV expressions here. This function is called |
5934 | // from deep in the call stack, and calling getSCEV (on a sext instruction, |
5935 | // say) can end up caching a suboptimal value. |
5936 | |
5937 | // FIXME: without the explicit `this` receiver below, MSVC errors out with |
5938 | // C2352 and C2512 (otherwise it isn't needed). |
5939 | |
5940 | const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue); |
5941 | const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue); |
5942 | const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue); |
5943 | const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue); |
5944 | |
5945 | ConstantRange TrueRange = |
5946 | this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth); |
5947 | ConstantRange FalseRange = |
5948 | this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth); |
5949 | |
5950 | return TrueRange.unionWith(FalseRange); |
5951 | } |
5952 | |
5953 | SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) { |
5954 | if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap; |
5955 | const BinaryOperator *BinOp = cast<BinaryOperator>(V); |
5956 | |
5957 | // Return early if there are no flags to propagate to the SCEV. |
5958 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
5959 | if (BinOp->hasNoUnsignedWrap()) |
5960 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW); |
5961 | if (BinOp->hasNoSignedWrap()) |
5962 | Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW); |
5963 | if (Flags == SCEV::FlagAnyWrap) |
5964 | return SCEV::FlagAnyWrap; |
5965 | |
5966 | return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap; |
5967 | } |
5968 | |
5969 | bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) { |
5970 | // Here we check that I is in the header of the innermost loop containing I, |
5971 | // since we only deal with instructions in the loop header. The actual loop we |
5972 | // need to check later will come from an add recurrence, but getting that |
5973 | // requires computing the SCEV of the operands, which can be expensive. This |
5974 | // check we can do cheaply to rule out some cases early. |
5975 | Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent()); |
5976 | if (InnermostContainingLoop == nullptr || |
5977 | InnermostContainingLoop->getHeader() != I->getParent()) |
5978 | return false; |
5979 | |
5980 | // Only proceed if we can prove that I does not yield poison. |
5981 | if (!programUndefinedIfFullPoison(I)) |
5982 | return false; |
5983 | |
5984 | // At this point we know that if I is executed, then it does not wrap |
5985 | // according to at least one of NSW or NUW. If I is not executed, then we do |
5986 | // not know if the calculation that I represents would wrap. Multiple |
5987 | // instructions can map to the same SCEV. If we apply NSW or NUW from I to |
5988 | // the SCEV, we must guarantee no wrapping for that SCEV also when it is |
5989 | // derived from other instructions that map to the same SCEV. We cannot make |
5990 | // that guarantee for cases where I is not executed. So we need to find the |
5991 | // loop that I is considered in relation to and prove that I is executed for |
5992 | // every iteration of that loop. That implies that the value that I |
5993 | // calculates does not wrap anywhere in the loop, so then we can apply the |
5994 | // flags to the SCEV. |
5995 | // |
5996 | // We check isLoopInvariant to disambiguate in case we are adding recurrences |
5997 | // from different loops, so that we know which loop to prove that I is |
5998 | // executed in. |
5999 | for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) { |
6000 | // I could be an extractvalue from a call to an overflow intrinsic. |
6001 | // TODO: We can do better here in some cases. |
6002 | if (!isSCEVable(I->getOperand(OpIndex)->getType())) |
6003 | return false; |
6004 | const SCEV *Op = getSCEV(I->getOperand(OpIndex)); |
6005 | if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) { |
6006 | bool AllOtherOpsLoopInvariant = true; |
6007 | for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands(); |
6008 | ++OtherOpIndex) { |
6009 | if (OtherOpIndex != OpIndex) { |
6010 | const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex)); |
6011 | if (!isLoopInvariant(OtherOp, AddRec->getLoop())) { |
6012 | AllOtherOpsLoopInvariant = false; |
6013 | break; |
6014 | } |
6015 | } |
6016 | } |
6017 | if (AllOtherOpsLoopInvariant && |
6018 | isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop())) |
6019 | return true; |
6020 | } |
6021 | } |
6022 | return false; |
6023 | } |
6024 | |
6025 | bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) { |
6026 | // If we know that \c I can never be poison period, then that's enough. |
6027 | if (isSCEVExprNeverPoison(I)) |
6028 | return true; |
6029 | |
6030 | // For an add recurrence specifically, we assume that infinite loops without |
6031 | // side effects are undefined behavior, and then reason as follows: |
6032 | // |
6033 | // If the add recurrence is poison in any iteration, it is poison on all |
6034 | // future iterations (since incrementing poison yields poison). If the result |
6035 | // of the add recurrence is fed into the loop latch condition and the loop |
6036 | // does not contain any throws or exiting blocks other than the latch, we now |
6037 | // have the ability to "choose" whether the backedge is taken or not (by |
6038 | // choosing a sufficiently evil value for the poison feeding into the branch) |
6039 | // for every iteration including and after the one in which \p I first became |
6040 | // poison. There are two possibilities (let's call the iteration in which \p |
6041 | // I first became poison as K): |
6042 | // |
6043 | // 1. In the set of iterations including and after K, the loop body executes |
6044 | // no side effects. In this case executing the backege an infinte number |
6045 | // of times will yield undefined behavior. |
6046 | // |
6047 | // 2. In the set of iterations including and after K, the loop body executes |
6048 | // at least one side effect. In this case, that specific instance of side |
6049 | // effect is control dependent on poison, which also yields undefined |
6050 | // behavior. |
6051 | |
6052 | auto *ExitingBB = L->getExitingBlock(); |
6053 | auto *LatchBB = L->getLoopLatch(); |
6054 | if (!ExitingBB || !LatchBB || ExitingBB != LatchBB) |
6055 | return false; |
6056 | |
6057 | SmallPtrSet<const Instruction *, 16> Pushed; |
6058 | SmallVector<const Instruction *, 8> PoisonStack; |
6059 | |
6060 | // We start by assuming \c I, the post-inc add recurrence, is poison. Only |
6061 | // things that are known to be fully poison under that assumption go on the |
6062 | // PoisonStack. |
6063 | Pushed.insert(I); |
6064 | PoisonStack.push_back(I); |
6065 | |
6066 | bool LatchControlDependentOnPoison = false; |
6067 | while (!PoisonStack.empty() && !LatchControlDependentOnPoison) { |
6068 | const Instruction *Poison = PoisonStack.pop_back_val(); |
6069 | |
6070 | for (auto *PoisonUser : Poison->users()) { |
6071 | if (propagatesFullPoison(cast<Instruction>(PoisonUser))) { |
6072 | if (Pushed.insert(cast<Instruction>(PoisonUser)).second) |
6073 | PoisonStack.push_back(cast<Instruction>(PoisonUser)); |
6074 | } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) { |
6075 | assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast <void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6075, __PRETTY_FUNCTION__)); |
6076 | if (BI->getParent() == LatchBB) { |
6077 | LatchControlDependentOnPoison = true; |
6078 | break; |
6079 | } |
6080 | } |
6081 | } |
6082 | } |
6083 | |
6084 | return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L); |
6085 | } |
6086 | |
6087 | ScalarEvolution::LoopProperties |
6088 | ScalarEvolution::getLoopProperties(const Loop *L) { |
6089 | using LoopProperties = ScalarEvolution::LoopProperties; |
6090 | |
6091 | auto Itr = LoopPropertiesCache.find(L); |
6092 | if (Itr == LoopPropertiesCache.end()) { |
6093 | auto HasSideEffects = [](Instruction *I) { |
6094 | if (auto *SI = dyn_cast<StoreInst>(I)) |
6095 | return !SI->isSimple(); |
6096 | |
6097 | return I->mayHaveSideEffects(); |
6098 | }; |
6099 | |
6100 | LoopProperties LP = {/* HasNoAbnormalExits */ true, |
6101 | /*HasNoSideEffects*/ true}; |
6102 | |
6103 | for (auto *BB : L->getBlocks()) |
6104 | for (auto &I : *BB) { |
6105 | if (!isGuaranteedToTransferExecutionToSuccessor(&I)) |
6106 | LP.HasNoAbnormalExits = false; |
6107 | if (HasSideEffects(&I)) |
6108 | LP.HasNoSideEffects = false; |
6109 | if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects) |
6110 | break; // We're already as pessimistic as we can get. |
6111 | } |
6112 | |
6113 | auto InsertPair = LoopPropertiesCache.insert({L, LP}); |
6114 | assert(InsertPair.second && "We just checked!")((InsertPair.second && "We just checked!") ? static_cast <void> (0) : __assert_fail ("InsertPair.second && \"We just checked!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6114, __PRETTY_FUNCTION__)); |
6115 | Itr = InsertPair.first; |
6116 | } |
6117 | |
6118 | return Itr->second; |
6119 | } |
6120 | |
6121 | const SCEV *ScalarEvolution::createSCEV(Value *V) { |
6122 | if (!isSCEVable(V->getType())) |
6123 | return getUnknown(V); |
6124 | |
6125 | if (Instruction *I = dyn_cast<Instruction>(V)) { |
6126 | // Don't attempt to analyze instructions in blocks that aren't |
6127 | // reachable. Such instructions don't matter, and they aren't required |
6128 | // to obey basic rules for definitions dominating uses which this |
6129 | // analysis depends on. |
6130 | if (!DT.isReachableFromEntry(I->getParent())) |
6131 | return getUnknown(V); |
6132 | } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) |
6133 | return getConstant(CI); |
6134 | else if (isa<ConstantPointerNull>(V)) |
6135 | return getZero(V->getType()); |
6136 | else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) |
6137 | return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee()); |
6138 | else if (!isa<ConstantExpr>(V)) |
6139 | return getUnknown(V); |
6140 | |
6141 | Operator *U = cast<Operator>(V); |
6142 | if (auto BO = MatchBinaryOp(U, DT)) { |
6143 | switch (BO->Opcode) { |
6144 | case Instruction::Add: { |
6145 | // The simple thing to do would be to just call getSCEV on both operands |
6146 | // and call getAddExpr with the result. However if we're looking at a |
6147 | // bunch of things all added together, this can be quite inefficient, |
6148 | // because it leads to N-1 getAddExpr calls for N ultimate operands. |
6149 | // Instead, gather up all the operands and make a single getAddExpr call. |
6150 | // LLVM IR canonical form means we need only traverse the left operands. |
6151 | SmallVector<const SCEV *, 4> AddOps; |
6152 | do { |
6153 | if (BO->Op) { |
6154 | if (auto *OpSCEV = getExistingSCEV(BO->Op)) { |
6155 | AddOps.push_back(OpSCEV); |
6156 | break; |
6157 | } |
6158 | |
6159 | // If a NUW or NSW flag can be applied to the SCEV for this |
6160 | // addition, then compute the SCEV for this addition by itself |
6161 | // with a separate call to getAddExpr. We need to do that |
6162 | // instead of pushing the operands of the addition onto AddOps, |
6163 | // since the flags are only known to apply to this particular |
6164 | // addition - they may not apply to other additions that can be |
6165 | // formed with operands from AddOps. |
6166 | const SCEV *RHS = getSCEV(BO->RHS); |
6167 | SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op); |
6168 | if (Flags != SCEV::FlagAnyWrap) { |
6169 | const SCEV *LHS = getSCEV(BO->LHS); |
6170 | if (BO->Opcode == Instruction::Sub) |
6171 | AddOps.push_back(getMinusSCEV(LHS, RHS, Flags)); |
6172 | else |
6173 | AddOps.push_back(getAddExpr(LHS, RHS, Flags)); |
6174 | break; |
6175 | } |
6176 | } |
6177 | |
6178 | if (BO->Opcode == Instruction::Sub) |
6179 | AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS))); |
6180 | else |
6181 | AddOps.push_back(getSCEV(BO->RHS)); |
6182 | |
6183 | auto NewBO = MatchBinaryOp(BO->LHS, DT); |
6184 | if (!NewBO || (NewBO->Opcode != Instruction::Add && |
6185 | NewBO->Opcode != Instruction::Sub)) { |
6186 | AddOps.push_back(getSCEV(BO->LHS)); |
6187 | break; |
6188 | } |
6189 | BO = NewBO; |
6190 | } while (true); |
6191 | |
6192 | return getAddExpr(AddOps); |
6193 | } |
6194 | |
6195 | case Instruction::Mul: { |
6196 | SmallVector<const SCEV *, 4> MulOps; |
6197 | do { |
6198 | if (BO->Op) { |
6199 | if (auto *OpSCEV = getExistingSCEV(BO->Op)) { |
6200 | MulOps.push_back(OpSCEV); |
6201 | break; |
6202 | } |
6203 | |
6204 | SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op); |
6205 | if (Flags != SCEV::FlagAnyWrap) { |
6206 | MulOps.push_back( |
6207 | getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags)); |
6208 | break; |
6209 | } |
6210 | } |
6211 | |
6212 | MulOps.push_back(getSCEV(BO->RHS)); |
6213 | auto NewBO = MatchBinaryOp(BO->LHS, DT); |
6214 | if (!NewBO || NewBO->Opcode != Instruction::Mul) { |
6215 | MulOps.push_back(getSCEV(BO->LHS)); |
6216 | break; |
6217 | } |
6218 | BO = NewBO; |
6219 | } while (true); |
6220 | |
6221 | return getMulExpr(MulOps); |
6222 | } |
6223 | case Instruction::UDiv: |
6224 | return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS)); |
6225 | case Instruction::URem: |
6226 | return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS)); |
6227 | case Instruction::Sub: { |
6228 | SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap; |
6229 | if (BO->Op) |
6230 | Flags = getNoWrapFlagsFromUB(BO->Op); |
6231 | return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags); |
6232 | } |
6233 | case Instruction::And: |
6234 | // For an expression like x&255 that merely masks off the high bits, |
6235 | // use zext(trunc(x)) as the SCEV expression. |
6236 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) { |
6237 | if (CI->isZero()) |
6238 | return getSCEV(BO->RHS); |
6239 | if (CI->isMinusOne()) |
6240 | return getSCEV(BO->LHS); |
6241 | const APInt &A = CI->getValue(); |
6242 | |
6243 | // Instcombine's ShrinkDemandedConstant may strip bits out of |
6244 | // constants, obscuring what would otherwise be a low-bits mask. |
6245 | // Use computeKnownBits to compute what ShrinkDemandedConstant |
6246 | // knew about to reconstruct a low-bits mask value. |
6247 | unsigned LZ = A.countLeadingZeros(); |
6248 | unsigned TZ = A.countTrailingZeros(); |
6249 | unsigned BitWidth = A.getBitWidth(); |
6250 | KnownBits Known(BitWidth); |
6251 | computeKnownBits(BO->LHS, Known, getDataLayout(), |
6252 | 0, &AC, nullptr, &DT); |
6253 | |
6254 | APInt EffectiveMask = |
6255 | APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ); |
6256 | if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) { |
6257 | const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ)); |
6258 | const SCEV *LHS = getSCEV(BO->LHS); |
6259 | const SCEV *ShiftedLHS = nullptr; |
6260 | if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) { |
6261 | if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) { |
6262 | // For an expression like (x * 8) & 8, simplify the multiply. |
6263 | unsigned MulZeros = OpC->getAPInt().countTrailingZeros(); |
6264 | unsigned GCD = std::min(MulZeros, TZ); |
6265 | APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD); |
6266 | SmallVector<const SCEV*, 4> MulOps; |
6267 | MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD))); |
6268 | MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end()); |
6269 | auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags()); |
6270 | ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt)); |
6271 | } |
6272 | } |
6273 | if (!ShiftedLHS) |
6274 | ShiftedLHS = getUDivExpr(LHS, MulCount); |
6275 | return getMulExpr( |
6276 | getZeroExtendExpr( |
6277 | getTruncateExpr(ShiftedLHS, |
6278 | IntegerType::get(getContext(), BitWidth - LZ - TZ)), |
6279 | BO->LHS->getType()), |
6280 | MulCount); |
6281 | } |
6282 | } |
6283 | break; |
6284 | |
6285 | case Instruction::Or: |
6286 | // If the RHS of the Or is a constant, we may have something like: |
6287 | // X*4+1 which got turned into X*4|1. Handle this as an Add so loop |
6288 | // optimizations will transparently handle this case. |
6289 | // |
6290 | // In order for this transformation to be safe, the LHS must be of the |
6291 | // form X*(2^n) and the Or constant must be less than 2^n. |
6292 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) { |
6293 | const SCEV *LHS = getSCEV(BO->LHS); |
6294 | const APInt &CIVal = CI->getValue(); |
6295 | if (GetMinTrailingZeros(LHS) >= |
6296 | (CIVal.getBitWidth() - CIVal.countLeadingZeros())) { |
6297 | // Build a plain add SCEV. |
6298 | const SCEV *S = getAddExpr(LHS, getSCEV(CI)); |
6299 | // If the LHS of the add was an addrec and it has no-wrap flags, |
6300 | // transfer the no-wrap flags, since an or won't introduce a wrap. |
6301 | if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) { |
6302 | const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS); |
6303 | const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags( |
6304 | OldAR->getNoWrapFlags()); |
6305 | } |
6306 | return S; |
6307 | } |
6308 | } |
6309 | break; |
6310 | |
6311 | case Instruction::Xor: |
6312 | if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) { |
6313 | // If the RHS of xor is -1, then this is a not operation. |
6314 | if (CI->isMinusOne()) |
6315 | return getNotSCEV(getSCEV(BO->LHS)); |
6316 | |
6317 | // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask. |
6318 | // This is a variant of the check for xor with -1, and it handles |
6319 | // the case where instcombine has trimmed non-demanded bits out |
6320 | // of an xor with -1. |
6321 | if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS)) |
6322 | if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1))) |
6323 | if (LBO->getOpcode() == Instruction::And && |
6324 | LCI->getValue() == CI->getValue()) |
6325 | if (const SCEVZeroExtendExpr *Z = |
6326 | dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) { |
6327 | Type *UTy = BO->LHS->getType(); |
6328 | const SCEV *Z0 = Z->getOperand(); |
6329 | Type *Z0Ty = Z0->getType(); |
6330 | unsigned Z0TySize = getTypeSizeInBits(Z0Ty); |
6331 | |
6332 | // If C is a low-bits mask, the zero extend is serving to |
6333 | // mask off the high bits. Complement the operand and |
6334 | // re-apply the zext. |
6335 | if (CI->getValue().isMask(Z0TySize)) |
6336 | return getZeroExtendExpr(getNotSCEV(Z0), UTy); |
6337 | |
6338 | // If C is a single bit, it may be in the sign-bit position |
6339 | // before the zero-extend. In this case, represent the xor |
6340 | // using an add, which is equivalent, and re-apply the zext. |
6341 | APInt Trunc = CI->getValue().trunc(Z0TySize); |
6342 | if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() && |
6343 | Trunc.isSignMask()) |
6344 | return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)), |
6345 | UTy); |
6346 | } |
6347 | } |
6348 | break; |
6349 | |
6350 | case Instruction::Shl: |
6351 | // Turn shift left of a constant amount into a multiply. |
6352 | if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) { |
6353 | uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth(); |
6354 | |
6355 | // If the shift count is not less than the bitwidth, the result of |
6356 | // the shift is undefined. Don't try to analyze it, because the |
6357 | // resolution chosen here may differ from the resolution chosen in |
6358 | // other parts of the compiler. |
6359 | if (SA->getValue().uge(BitWidth)) |
6360 | break; |
6361 | |
6362 | // It is currently not resolved how to interpret NSW for left |
6363 | // shift by BitWidth - 1, so we avoid applying flags in that |
6364 | // case. Remove this check (or this comment) once the situation |
6365 | // is resolved. See |
6366 | // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html |
6367 | // and http://reviews.llvm.org/D8890 . |
6368 | auto Flags = SCEV::FlagAnyWrap; |
6369 | if (BO->Op && SA->getValue().ult(BitWidth - 1)) |
6370 | Flags = getNoWrapFlagsFromUB(BO->Op); |
6371 | |
6372 | Constant *X = ConstantInt::get( |
6373 | getContext(), APInt::getOneBitSet(BitWidth, SA->getZExtValue())); |
6374 | return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags); |
6375 | } |
6376 | break; |
6377 | |
6378 | case Instruction::AShr: { |
6379 | // AShr X, C, where C is a constant. |
6380 | ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS); |
6381 | if (!CI) |
6382 | break; |
6383 | |
6384 | Type *OuterTy = BO->LHS->getType(); |
6385 | uint64_t BitWidth = getTypeSizeInBits(OuterTy); |
6386 | // If the shift count is not less than the bitwidth, the result of |
6387 | // the shift is undefined. Don't try to analyze it, because the |
6388 | // resolution chosen here may differ from the resolution chosen in |
6389 | // other parts of the compiler. |
6390 | if (CI->getValue().uge(BitWidth)) |
6391 | break; |
6392 | |
6393 | if (CI->isZero()) |
6394 | return getSCEV(BO->LHS); // shift by zero --> noop |
6395 | |
6396 | uint64_t AShrAmt = CI->getZExtValue(); |
6397 | Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt); |
6398 | |
6399 | Operator *L = dyn_cast<Operator>(BO->LHS); |
6400 | if (L && L->getOpcode() == Instruction::Shl) { |
6401 | // X = Shl A, n |
6402 | // Y = AShr X, m |
6403 | // Both n and m are constant. |
6404 | |
6405 | const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0)); |
6406 | if (L->getOperand(1) == BO->RHS) |
6407 | // For a two-shift sext-inreg, i.e. n = m, |
6408 | // use sext(trunc(x)) as the SCEV expression. |
6409 | return getSignExtendExpr( |
6410 | getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy); |
6411 | |
6412 | ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1)); |
6413 | if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) { |
6414 | uint64_t ShlAmt = ShlAmtCI->getZExtValue(); |
6415 | if (ShlAmt > AShrAmt) { |
6416 | // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV |
6417 | // expression. We already checked that ShlAmt < BitWidth, so |
6418 | // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as |
6419 | // ShlAmt - AShrAmt < Amt. |
6420 | APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt, |
6421 | ShlAmt - AShrAmt); |
6422 | return getSignExtendExpr( |
6423 | getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy), |
6424 | getConstant(Mul)), OuterTy); |
6425 | } |
6426 | } |
6427 | } |
6428 | break; |
6429 | } |
6430 | } |
6431 | } |
6432 | |
6433 | switch (U->getOpcode()) { |
6434 | case Instruction::Trunc: |
6435 | return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType()); |
6436 | |
6437 | case Instruction::ZExt: |
6438 | return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType()); |
6439 | |
6440 | case Instruction::SExt: |
6441 | if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) { |
6442 | // The NSW flag of a subtract does not always survive the conversion to |
6443 | // A + (-1)*B. By pushing sign extension onto its operands we are much |
6444 | // more likely to preserve NSW and allow later AddRec optimisations. |
6445 | // |
6446 | // NOTE: This is effectively duplicating this logic from getSignExtend: |
6447 | // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw> |
6448 | // but by that point the NSW information has potentially been lost. |
6449 | if (BO->Opcode == Instruction::Sub && BO->IsNSW) { |
6450 | Type *Ty = U->getType(); |
6451 | auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty); |
6452 | auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty); |
6453 | return getMinusSCEV(V1, V2, SCEV::FlagNSW); |
6454 | } |
6455 | } |
6456 | return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType()); |
6457 | |
6458 | case Instruction::BitCast: |
6459 | // BitCasts are no-op casts so we just eliminate the cast. |
6460 | if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType())) |
6461 | return getSCEV(U->getOperand(0)); |
6462 | break; |
6463 | |
6464 | // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can |
6465 | // lead to pointer expressions which cannot safely be expanded to GEPs, |
6466 | // because ScalarEvolution doesn't respect the GEP aliasing rules when |
6467 | // simplifying integer expressions. |
6468 | |
6469 | case Instruction::GetElementPtr: |
6470 | return createNodeForGEP(cast<GEPOperator>(U)); |
6471 | |
6472 | case Instruction::PHI: |
6473 | return createNodeForPHI(cast<PHINode>(U)); |
6474 | |
6475 | case Instruction::Select: |
6476 | // U can also be a select constant expr, which let fall through. Since |
6477 | // createNodeForSelect only works for a condition that is an `ICmpInst`, and |
6478 | // constant expressions cannot have instructions as operands, we'd have |
6479 | // returned getUnknown for a select constant expressions anyway. |
6480 | if (isa<Instruction>(U)) |
6481 | return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0), |
6482 | U->getOperand(1), U->getOperand(2)); |
6483 | break; |
6484 | |
6485 | case Instruction::Call: |
6486 | case Instruction::Invoke: |
6487 | if (Value *RV = CallSite(U).getReturnedArgOperand()) |
6488 | return getSCEV(RV); |
6489 | break; |
6490 | } |
6491 | |
6492 | return getUnknown(V); |
6493 | } |
6494 | |
6495 | //===----------------------------------------------------------------------===// |
6496 | // Iteration Count Computation Code |
6497 | // |
6498 | |
6499 | static unsigned getConstantTripCount(const SCEVConstant *ExitCount) { |
6500 | if (!ExitCount) |
6501 | return 0; |
6502 | |
6503 | ConstantInt *ExitConst = ExitCount->getValue(); |
6504 | |
6505 | // Guard against huge trip counts. |
6506 | if (ExitConst->getValue().getActiveBits() > 32) |
6507 | return 0; |
6508 | |
6509 | // In case of integer overflow, this returns 0, which is correct. |
6510 | return ((unsigned)ExitConst->getZExtValue()) + 1; |
6511 | } |
6512 | |
6513 | unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) { |
6514 | if (BasicBlock *ExitingBB = L->getExitingBlock()) |
6515 | return getSmallConstantTripCount(L, ExitingBB); |
6516 | |
6517 | // No trip count information for multiple exits. |
6518 | return 0; |
6519 | } |
6520 | |
6521 | unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L, |
6522 | BasicBlock *ExitingBlock) { |
6523 | assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!" ) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6523, __PRETTY_FUNCTION__)); |
6524 | assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6525, __PRETTY_FUNCTION__)) |
6525 | "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6525, __PRETTY_FUNCTION__)); |
6526 | const SCEVConstant *ExitCount = |
6527 | dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock)); |
6528 | return getConstantTripCount(ExitCount); |
6529 | } |
6530 | |
6531 | unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) { |
6532 | const auto *MaxExitCount = |
6533 | dyn_cast<SCEVConstant>(getMaxBackedgeTakenCount(L)); |
6534 | return getConstantTripCount(MaxExitCount); |
6535 | } |
6536 | |
6537 | unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) { |
6538 | if (BasicBlock *ExitingBB = L->getExitingBlock()) |
6539 | return getSmallConstantTripMultiple(L, ExitingBB); |
6540 | |
6541 | // No trip multiple information for multiple exits. |
6542 | return 0; |
6543 | } |
6544 | |
6545 | /// Returns the largest constant divisor of the trip count of this loop as a |
6546 | /// normal unsigned value, if possible. This means that the actual trip count is |
6547 | /// always a multiple of the returned value (don't forget the trip count could |
6548 | /// very well be zero as well!). |
6549 | /// |
6550 | /// Returns 1 if the trip count is unknown or not guaranteed to be the |
6551 | /// multiple of a constant (which is also the case if the trip count is simply |
6552 | /// constant, use getSmallConstantTripCount for that case), Will also return 1 |
6553 | /// if the trip count is very large (>= 2^32). |
6554 | /// |
6555 | /// As explained in the comments for getSmallConstantTripCount, this assumes |
6556 | /// that control exits the loop via ExitingBlock. |
6557 | unsigned |
6558 | ScalarEvolution::getSmallConstantTripMultiple(const Loop *L, |
6559 | BasicBlock *ExitingBlock) { |
6560 | assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!" ) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6560, __PRETTY_FUNCTION__)); |
6561 | assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6562, __PRETTY_FUNCTION__)) |
6562 | "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6562, __PRETTY_FUNCTION__)); |
6563 | const SCEV *ExitCount = getExitCount(L, ExitingBlock); |
6564 | if (ExitCount == getCouldNotCompute()) |
6565 | return 1; |
6566 | |
6567 | // Get the trip count from the BE count by adding 1. |
6568 | const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType())); |
6569 | |
6570 | const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr); |
6571 | if (!TC) |
6572 | // Attempt to factor more general cases. Returns the greatest power of |
6573 | // two divisor. If overflow happens, the trip count expression is still |
6574 | // divisible by the greatest power of 2 divisor returned. |
6575 | return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr)); |
6576 | |
6577 | ConstantInt *Result = TC->getValue(); |
6578 | |
6579 | // Guard against huge trip counts (this requires checking |
6580 | // for zero to handle the case where the trip count == -1 and the |
6581 | // addition wraps). |
6582 | if (!Result || Result->getValue().getActiveBits() > 32 || |
6583 | Result->getValue().getActiveBits() == 0) |
6584 | return 1; |
6585 | |
6586 | return (unsigned)Result->getZExtValue(); |
6587 | } |
6588 | |
6589 | /// Get the expression for the number of loop iterations for which this loop is |
6590 | /// guaranteed not to exit via ExitingBlock. Otherwise return |
6591 | /// SCEVCouldNotCompute. |
6592 | const SCEV *ScalarEvolution::getExitCount(const Loop *L, |
6593 | BasicBlock *ExitingBlock) { |
6594 | return getBackedgeTakenInfo(L).getExact(ExitingBlock, this); |
6595 | } |
6596 | |
6597 | const SCEV * |
6598 | ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L, |
6599 | SCEVUnionPredicate &Preds) { |
6600 | return getPredicatedBackedgeTakenInfo(L).getExact(L, this, &Preds); |
6601 | } |
6602 | |
6603 | const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) { |
6604 | return getBackedgeTakenInfo(L).getExact(L, this); |
6605 | } |
6606 | |
6607 | /// Similar to getBackedgeTakenCount, except return the least SCEV value that is |
6608 | /// known never to be less than the actual backedge taken count. |
6609 | const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) { |
6610 | return getBackedgeTakenInfo(L).getMax(this); |
6611 | } |
6612 | |
6613 | bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) { |
6614 | return getBackedgeTakenInfo(L).isMaxOrZero(this); |
6615 | } |
6616 | |
6617 | /// Push PHI nodes in the header of the given loop onto the given Worklist. |
6618 | static void |
6619 | PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) { |
6620 | BasicBlock *Header = L->getHeader(); |
6621 | |
6622 | // Push all Loop-header PHIs onto the Worklist stack. |
6623 | for (PHINode &PN : Header->phis()) |
6624 | Worklist.push_back(&PN); |
6625 | } |
6626 | |
6627 | const ScalarEvolution::BackedgeTakenInfo & |
6628 | ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) { |
6629 | auto &BTI = getBackedgeTakenInfo(L); |
6630 | if (BTI.hasFullInfo()) |
6631 | return BTI; |
6632 | |
6633 | auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()}); |
6634 | |
6635 | if (!Pair.second) |
6636 | return Pair.first->second; |
6637 | |
6638 | BackedgeTakenInfo Result = |
6639 | computeBackedgeTakenCount(L, /*AllowPredicates=*/true); |
6640 | |
6641 | return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result); |
6642 | } |
6643 | |
6644 | const ScalarEvolution::BackedgeTakenInfo & |
6645 | ScalarEvolution::getBackedgeTakenInfo(const Loop *L) { |
6646 | // Initially insert an invalid entry for this loop. If the insertion |
6647 | // succeeds, proceed to actually compute a backedge-taken count and |
6648 | // update the value. The temporary CouldNotCompute value tells SCEV |
6649 | // code elsewhere that it shouldn't attempt to request a new |
6650 | // backedge-taken count, which could result in infinite recursion. |
6651 | std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair = |
6652 | BackedgeTakenCounts.insert({L, BackedgeTakenInfo()}); |
6653 | if (!Pair.second) |
6654 | return Pair.first->second; |
6655 | |
6656 | // computeBackedgeTakenCount may allocate memory for its result. Inserting it |
6657 | // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result |
6658 | // must be cleared in this scope. |
6659 | BackedgeTakenInfo Result = computeBackedgeTakenCount(L); |
6660 | |
6661 | // In product build, there are no usage of statistic. |
6662 | (void)NumTripCountsComputed; |
6663 | (void)NumTripCountsNotComputed; |
6664 | #if LLVM_ENABLE_STATS1 || !defined(NDEBUG) |
6665 | const SCEV *BEExact = Result.getExact(L, this); |
6666 | if (BEExact != getCouldNotCompute()) { |
6667 | assert(isLoopInvariant(BEExact, L) &&((isLoopInvariant(BEExact, L) && isLoopInvariant(Result .getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6669, __PRETTY_FUNCTION__)) |
6668 | isLoopInvariant(Result.getMax(this), L) &&((isLoopInvariant(BEExact, L) && isLoopInvariant(Result .getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6669, __PRETTY_FUNCTION__)) |
6669 | "Computed backedge-taken count isn't loop invariant for loop!")((isLoopInvariant(BEExact, L) && isLoopInvariant(Result .getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!" ) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(BEExact, L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6669, __PRETTY_FUNCTION__)); |
6670 | ++NumTripCountsComputed; |
6671 | } |
6672 | else if (Result.getMax(this) == getCouldNotCompute() && |
6673 | isa<PHINode>(L->getHeader()->begin())) { |
6674 | // Only count loops that have phi nodes as not being computable. |
6675 | ++NumTripCountsNotComputed; |
6676 | } |
6677 | #endif // LLVM_ENABLE_STATS || !defined(NDEBUG) |
6678 | |
6679 | // Now that we know more about the trip count for this loop, forget any |
6680 | // existing SCEV values for PHI nodes in this loop since they are only |
6681 | // conservative estimates made without the benefit of trip count |
6682 | // information. This is similar to the code in forgetLoop, except that |
6683 | // it handles SCEVUnknown PHI nodes specially. |
6684 | if (Result.hasAnyInfo()) { |
6685 | SmallVector<Instruction *, 16> Worklist; |
6686 | PushLoopPHIs(L, Worklist); |
6687 | |
6688 | SmallPtrSet<Instruction *, 8> Discovered; |
6689 | while (!Worklist.empty()) { |
6690 | Instruction *I = Worklist.pop_back_val(); |
6691 | |
6692 | ValueExprMapType::iterator It = |
6693 | ValueExprMap.find_as(static_cast<Value *>(I)); |
6694 | if (It != ValueExprMap.end()) { |
6695 | const SCEV *Old = It->second; |
6696 | |
6697 | // SCEVUnknown for a PHI either means that it has an unrecognized |
6698 | // structure, or it's a PHI that's in the progress of being computed |
6699 | // by createNodeForPHI. In the former case, additional loop trip |
6700 | // count information isn't going to change anything. In the later |
6701 | // case, createNodeForPHI will perform the necessary updates on its |
6702 | // own when it gets to that point. |
6703 | if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) { |
6704 | eraseValueFromMap(It->first); |
6705 | forgetMemoizedResults(Old); |
6706 | } |
6707 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
6708 | ConstantEvolutionLoopExitValue.erase(PN); |
6709 | } |
6710 | |
6711 | // Since we don't need to invalidate anything for correctness and we're |
6712 | // only invalidating to make SCEV's results more precise, we get to stop |
6713 | // early to avoid invalidating too much. This is especially important in |
6714 | // cases like: |
6715 | // |
6716 | // %v = f(pn0, pn1) // pn0 and pn1 used through some other phi node |
6717 | // loop0: |
6718 | // %pn0 = phi |
6719 | // ... |
6720 | // loop1: |
6721 | // %pn1 = phi |
6722 | // ... |
6723 | // |
6724 | // where both loop0 and loop1's backedge taken count uses the SCEV |
6725 | // expression for %v. If we don't have the early stop below then in cases |
6726 | // like the above, getBackedgeTakenInfo(loop1) will clear out the trip |
6727 | // count for loop0 and getBackedgeTakenInfo(loop0) will clear out the trip |
6728 | // count for loop1, effectively nullifying SCEV's trip count cache. |
6729 | for (auto *U : I->users()) |
6730 | if (auto *I = dyn_cast<Instruction>(U)) { |
6731 | auto *LoopForUser = LI.getLoopFor(I->getParent()); |
6732 | if (LoopForUser && L->contains(LoopForUser) && |
6733 | Discovered.insert(I).second) |
6734 | Worklist.push_back(I); |
6735 | } |
6736 | } |
6737 | } |
6738 | |
6739 | // Re-lookup the insert position, since the call to |
6740 | // computeBackedgeTakenCount above could result in a |
6741 | // recusive call to getBackedgeTakenInfo (on a different |
6742 | // loop), which would invalidate the iterator computed |
6743 | // earlier. |
6744 | return BackedgeTakenCounts.find(L)->second = std::move(Result); |
6745 | } |
6746 | |
6747 | void ScalarEvolution::forgetLoop(const Loop *L) { |
6748 | // Drop any stored trip count value. |
6749 | auto RemoveLoopFromBackedgeMap = |
6750 | [](DenseMap<const Loop *, BackedgeTakenInfo> &Map, const Loop *L) { |
6751 | auto BTCPos = Map.find(L); |
6752 | if (BTCPos != Map.end()) { |
6753 | BTCPos->second.clear(); |
6754 | Map.erase(BTCPos); |
6755 | } |
6756 | }; |
6757 | |
6758 | SmallVector<const Loop *, 16> LoopWorklist(1, L); |
6759 | SmallVector<Instruction *, 32> Worklist; |
6760 | SmallPtrSet<Instruction *, 16> Visited; |
6761 | |
6762 | // Iterate over all the loops and sub-loops to drop SCEV information. |
6763 | while (!LoopWorklist.empty()) { |
6764 | auto *CurrL = LoopWorklist.pop_back_val(); |
6765 | |
6766 | RemoveLoopFromBackedgeMap(BackedgeTakenCounts, CurrL); |
6767 | RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts, CurrL); |
6768 | |
6769 | // Drop information about predicated SCEV rewrites for this loop. |
6770 | for (auto I = PredicatedSCEVRewrites.begin(); |
6771 | I != PredicatedSCEVRewrites.end();) { |
6772 | std::pair<const SCEV *, const Loop *> Entry = I->first; |
6773 | if (Entry.second == CurrL) |
6774 | PredicatedSCEVRewrites.erase(I++); |
6775 | else |
6776 | ++I; |
6777 | } |
6778 | |
6779 | auto LoopUsersItr = LoopUsers.find(CurrL); |
6780 | if (LoopUsersItr != LoopUsers.end()) { |
6781 | for (auto *S : LoopUsersItr->second) |
6782 | forgetMemoizedResults(S); |
6783 | LoopUsers.erase(LoopUsersItr); |
6784 | } |
6785 | |
6786 | // Drop information about expressions based on loop-header PHIs. |
6787 | PushLoopPHIs(CurrL, Worklist); |
6788 | |
6789 | while (!Worklist.empty()) { |
6790 | Instruction *I = Worklist.pop_back_val(); |
6791 | if (!Visited.insert(I).second) |
6792 | continue; |
6793 | |
6794 | ValueExprMapType::iterator It = |
6795 | ValueExprMap.find_as(static_cast<Value *>(I)); |
6796 | if (It != ValueExprMap.end()) { |
6797 | eraseValueFromMap(It->first); |
6798 | forgetMemoizedResults(It->second); |
6799 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
6800 | ConstantEvolutionLoopExitValue.erase(PN); |
6801 | } |
6802 | |
6803 | PushDefUseChildren(I, Worklist); |
6804 | } |
6805 | |
6806 | LoopPropertiesCache.erase(CurrL); |
6807 | // Forget all contained loops too, to avoid dangling entries in the |
6808 | // ValuesAtScopes map. |
6809 | LoopWorklist.append(CurrL->begin(), CurrL->end()); |
6810 | } |
6811 | } |
6812 | |
6813 | void ScalarEvolution::forgetTopmostLoop(const Loop *L) { |
6814 | while (Loop *Parent = L->getParentLoop()) |
6815 | L = Parent; |
6816 | forgetLoop(L); |
6817 | } |
6818 | |
6819 | void ScalarEvolution::forgetValue(Value *V) { |
6820 | Instruction *I = dyn_cast<Instruction>(V); |
6821 | if (!I) return; |
6822 | |
6823 | // Drop information about expressions based on loop-header PHIs. |
6824 | SmallVector<Instruction *, 16> Worklist; |
6825 | Worklist.push_back(I); |
6826 | |
6827 | SmallPtrSet<Instruction *, 8> Visited; |
6828 | while (!Worklist.empty()) { |
6829 | I = Worklist.pop_back_val(); |
6830 | if (!Visited.insert(I).second) |
6831 | continue; |
6832 | |
6833 | ValueExprMapType::iterator It = |
6834 | ValueExprMap.find_as(static_cast<Value *>(I)); |
6835 | if (It != ValueExprMap.end()) { |
6836 | eraseValueFromMap(It->first); |
6837 | forgetMemoizedResults(It->second); |
6838 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
6839 | ConstantEvolutionLoopExitValue.erase(PN); |
6840 | } |
6841 | |
6842 | PushDefUseChildren(I, Worklist); |
6843 | } |
6844 | } |
6845 | |
6846 | /// Get the exact loop backedge taken count considering all loop exits. A |
6847 | /// computable result can only be returned for loops with all exiting blocks |
6848 | /// dominating the latch. howFarToZero assumes that the limit of each loop test |
6849 | /// is never skipped. This is a valid assumption as long as the loop exits via |
6850 | /// that test. For precise results, it is the caller's responsibility to specify |
6851 | /// the relevant loop exiting block using getExact(ExitingBlock, SE). |
6852 | const SCEV * |
6853 | ScalarEvolution::BackedgeTakenInfo::getExact(const Loop *L, ScalarEvolution *SE, |
6854 | SCEVUnionPredicate *Preds) const { |
6855 | // If any exits were not computable, the loop is not computable. |
6856 | if (!isComplete() || ExitNotTaken.empty()) |
6857 | return SE->getCouldNotCompute(); |
6858 | |
6859 | const BasicBlock *Latch = L->getLoopLatch(); |
6860 | // All exiting blocks we have collected must dominate the only backedge. |
6861 | if (!Latch) |
6862 | return SE->getCouldNotCompute(); |
6863 | |
6864 | // All exiting blocks we have gathered dominate loop's latch, so exact trip |
6865 | // count is simply a minimum out of all these calculated exit counts. |
6866 | SmallVector<const SCEV *, 2> Ops; |
6867 | for (auto &ENT : ExitNotTaken) { |
6868 | const SCEV *BECount = ENT.ExactNotTaken; |
6869 | assert(BECount != SE->getCouldNotCompute() && "Bad exit SCEV!")((BECount != SE->getCouldNotCompute() && "Bad exit SCEV!" ) ? static_cast<void> (0) : __assert_fail ("BECount != SE->getCouldNotCompute() && \"Bad exit SCEV!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6869, __PRETTY_FUNCTION__)); |
6870 | assert(SE->DT.dominates(ENT.ExitingBlock, Latch) &&((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate " "latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6872, __PRETTY_FUNCTION__)) |
6871 | "We should only have known counts for exiting blocks that dominate "((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate " "latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6872, __PRETTY_FUNCTION__)) |
6872 | "latch!")((SE->DT.dominates(ENT.ExitingBlock, Latch) && "We should only have known counts for exiting blocks that dominate " "latch!") ? static_cast<void> (0) : __assert_fail ("SE->DT.dominates(ENT.ExitingBlock, Latch) && \"We should only have known counts for exiting blocks that dominate \" \"latch!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6872, __PRETTY_FUNCTION__)); |
6873 | |
6874 | Ops.push_back(BECount); |
6875 | |
6876 | if (Preds && !ENT.hasAlwaysTruePredicate()) |
6877 | Preds->add(ENT.Predicate.get()); |
6878 | |
6879 | assert((Preds || ENT.hasAlwaysTruePredicate()) &&(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!" ) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6880, __PRETTY_FUNCTION__)) |
6880 | "Predicate should be always true!")(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!" ) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6880, __PRETTY_FUNCTION__)); |
6881 | } |
6882 | |
6883 | return SE->getUMinFromMismatchedTypes(Ops); |
6884 | } |
6885 | |
6886 | /// Get the exact not taken count for this loop exit. |
6887 | const SCEV * |
6888 | ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock, |
6889 | ScalarEvolution *SE) const { |
6890 | for (auto &ENT : ExitNotTaken) |
6891 | if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate()) |
6892 | return ENT.ExactNotTaken; |
6893 | |
6894 | return SE->getCouldNotCompute(); |
6895 | } |
6896 | |
6897 | /// getMax - Get the max backedge taken count for the loop. |
6898 | const SCEV * |
6899 | ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const { |
6900 | auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) { |
6901 | return !ENT.hasAlwaysTruePredicate(); |
6902 | }; |
6903 | |
6904 | if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax()) |
6905 | return SE->getCouldNotCompute(); |
6906 | |
6907 | assert((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) &&(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant >(getMax())) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6908, __PRETTY_FUNCTION__)) |
6908 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant >(getMax())) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6908, __PRETTY_FUNCTION__)); |
6909 | return getMax(); |
6910 | } |
6911 | |
6912 | bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const { |
6913 | auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) { |
6914 | return !ENT.hasAlwaysTruePredicate(); |
6915 | }; |
6916 | return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue); |
6917 | } |
6918 | |
6919 | bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S, |
6920 | ScalarEvolution *SE) const { |
6921 | if (getMax() && getMax() != SE->getCouldNotCompute() && |
6922 | SE->hasOperand(getMax(), S)) |
6923 | return true; |
6924 | |
6925 | for (auto &ENT : ExitNotTaken) |
6926 | if (ENT.ExactNotTaken != SE->getCouldNotCompute() && |
6927 | SE->hasOperand(ENT.ExactNotTaken, S)) |
6928 | return true; |
6929 | |
6930 | return false; |
6931 | } |
6932 | |
6933 | ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E) |
6934 | : ExactNotTaken(E), MaxNotTaken(E) { |
6935 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6937, __PRETTY_FUNCTION__)) |
6936 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6937, __PRETTY_FUNCTION__)) |
6937 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6937, __PRETTY_FUNCTION__)); |
6938 | } |
6939 | |
6940 | ScalarEvolution::ExitLimit::ExitLimit( |
6941 | const SCEV *E, const SCEV *M, bool MaxOrZero, |
6942 | ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList) |
6943 | : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) { |
6944 | assert((isa<SCEVCouldNotCompute>(ExactNotTaken) ||(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute >(MaxNotTaken)) && "Exact is not allowed to be less precise than Max" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6946, __PRETTY_FUNCTION__)) |
6945 | !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute >(MaxNotTaken)) && "Exact is not allowed to be less precise than Max" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6946, __PRETTY_FUNCTION__)) |
6946 | "Exact is not allowed to be less precise than Max")(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute >(MaxNotTaken)) && "Exact is not allowed to be less precise than Max" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6946, __PRETTY_FUNCTION__)); |
6947 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6949, __PRETTY_FUNCTION__)) |
6948 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6949, __PRETTY_FUNCTION__)) |
6949 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6949, __PRETTY_FUNCTION__)); |
6950 | for (auto *PredSet : PredSetList) |
6951 | for (auto *P : *PredSet) |
6952 | addPredicate(P); |
6953 | } |
6954 | |
6955 | ScalarEvolution::ExitLimit::ExitLimit( |
6956 | const SCEV *E, const SCEV *M, bool MaxOrZero, |
6957 | const SmallPtrSetImpl<const SCEVPredicate *> &PredSet) |
6958 | : ExitLimit(E, M, MaxOrZero, {&PredSet}) { |
6959 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6961, __PRETTY_FUNCTION__)) |
6960 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6961, __PRETTY_FUNCTION__)) |
6961 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6961, __PRETTY_FUNCTION__)); |
6962 | } |
6963 | |
6964 | ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M, |
6965 | bool MaxOrZero) |
6966 | : ExitLimit(E, M, MaxOrZero, None) { |
6967 | assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6969, __PRETTY_FUNCTION__)) |
6968 | isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6969, __PRETTY_FUNCTION__)) |
6969 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant >(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6969, __PRETTY_FUNCTION__)); |
6970 | } |
6971 | |
6972 | /// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each |
6973 | /// computable exit into a persistent ExitNotTakenInfo array. |
6974 | ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo( |
6975 | SmallVectorImpl<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo> |
6976 | &&ExitCounts, |
6977 | bool Complete, const SCEV *MaxCount, bool MaxOrZero) |
6978 | : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) { |
6979 | using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo; |
6980 | |
6981 | ExitNotTaken.reserve(ExitCounts.size()); |
6982 | std::transform( |
6983 | ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken), |
6984 | [&](const EdgeExitInfo &EEI) { |
6985 | BasicBlock *ExitBB = EEI.first; |
6986 | const ExitLimit &EL = EEI.second; |
6987 | if (EL.Predicates.empty()) |
6988 | return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, nullptr); |
6989 | |
6990 | std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate); |
6991 | for (auto *Pred : EL.Predicates) |
6992 | Predicate->add(Pred); |
6993 | |
6994 | return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, std::move(Predicate)); |
6995 | }); |
6996 | assert((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) &&(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant >(MaxCount)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6997, __PRETTY_FUNCTION__)) |
6997 | "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant >(MaxCount)) && "No point in having a non-constant max backedge taken count!" ) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 6997, __PRETTY_FUNCTION__)); |
6998 | } |
6999 | |
7000 | /// Invalidate this result and free the ExitNotTakenInfo array. |
7001 | void ScalarEvolution::BackedgeTakenInfo::clear() { |
7002 | ExitNotTaken.clear(); |
7003 | } |
7004 | |
7005 | /// Compute the number of times the backedge of the specified loop will execute. |
7006 | ScalarEvolution::BackedgeTakenInfo |
7007 | ScalarEvolution::computeBackedgeTakenCount(const Loop *L, |
7008 | bool AllowPredicates) { |
7009 | SmallVector<BasicBlock *, 8> ExitingBlocks; |
7010 | L->getExitingBlocks(ExitingBlocks); |
7011 | |
7012 | using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo; |
7013 | |
7014 | SmallVector<EdgeExitInfo, 4> ExitCounts; |
7015 | bool CouldComputeBECount = true; |
7016 | BasicBlock *Latch = L->getLoopLatch(); // may be NULL. |
7017 | const SCEV *MustExitMaxBECount = nullptr; |
7018 | const SCEV *MayExitMaxBECount = nullptr; |
7019 | bool MustExitMaxOrZero = false; |
7020 | |
7021 | // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts |
7022 | // and compute maxBECount. |
7023 | // Do a union of all the predicates here. |
7024 | for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) { |
7025 | BasicBlock *ExitBB = ExitingBlocks[i]; |
7026 | ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates); |
7027 | |
7028 | assert((AllowPredicates || EL.Predicates.empty()) &&(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!" ) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7029, __PRETTY_FUNCTION__)) |
7029 | "Predicated exit limit when predicates are not allowed!")(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!" ) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7029, __PRETTY_FUNCTION__)); |
7030 | |
7031 | // 1. For each exit that can be computed, add an entry to ExitCounts. |
7032 | // CouldComputeBECount is true only if all exits can be computed. |
7033 | if (EL.ExactNotTaken == getCouldNotCompute()) |
7034 | // We couldn't compute an exact value for this exit, so |
7035 | // we won't be able to compute an exact value for the loop. |
7036 | CouldComputeBECount = false; |
7037 | else |
7038 | ExitCounts.emplace_back(ExitBB, EL); |
7039 | |
7040 | // 2. Derive the loop's MaxBECount from each exit's max number of |
7041 | // non-exiting iterations. Partition the loop exits into two kinds: |
7042 | // LoopMustExits and LoopMayExits. |
7043 | // |
7044 | // If the exit dominates the loop latch, it is a LoopMustExit otherwise it |
7045 | // is a LoopMayExit. If any computable LoopMustExit is found, then |
7046 | // MaxBECount is the minimum EL.MaxNotTaken of computable |
7047 | // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum |
7048 | // EL.MaxNotTaken, where CouldNotCompute is considered greater than any |
7049 | // computable EL.MaxNotTaken. |
7050 | if (EL.MaxNotTaken != getCouldNotCompute() && Latch && |
7051 | DT.dominates(ExitBB, Latch)) { |
7052 | if (!MustExitMaxBECount) { |
7053 | MustExitMaxBECount = EL.MaxNotTaken; |
7054 | MustExitMaxOrZero = EL.MaxOrZero; |
7055 | } else { |
7056 | MustExitMaxBECount = |
7057 | getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken); |
7058 | } |
7059 | } else if (MayExitMaxBECount != getCouldNotCompute()) { |
7060 | if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute()) |
7061 | MayExitMaxBECount = EL.MaxNotTaken; |
7062 | else { |
7063 | MayExitMaxBECount = |
7064 | getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken); |
7065 | } |
7066 | } |
7067 | } |
7068 | const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount : |
7069 | (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute()); |
7070 | // The loop backedge will be taken the maximum or zero times if there's |
7071 | // a single exit that must be taken the maximum or zero times. |
7072 | bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1); |
7073 | return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount, |
7074 | MaxBECount, MaxOrZero); |
7075 | } |
7076 | |
7077 | ScalarEvolution::ExitLimit |
7078 | ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock, |
7079 | bool AllowPredicates) { |
7080 | assert(L->contains(ExitingBlock) && "Exit count for non-loop block?")((L->contains(ExitingBlock) && "Exit count for non-loop block?" ) ? static_cast<void> (0) : __assert_fail ("L->contains(ExitingBlock) && \"Exit count for non-loop block?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7080, __PRETTY_FUNCTION__)); |
7081 | // If our exiting block does not dominate the latch, then its connection with |
7082 | // loop's exit limit may be far from trivial. |
7083 | const BasicBlock *Latch = L->getLoopLatch(); |
7084 | if (!Latch || !DT.dominates(ExitingBlock, Latch)) |
7085 | return getCouldNotCompute(); |
7086 | |
7087 | bool IsOnlyExit = (L->getExitingBlock() != nullptr); |
7088 | Instruction *Term = ExitingBlock->getTerminator(); |
7089 | if (BranchInst *BI = dyn_cast<BranchInst>(Term)) { |
7090 | assert(BI->isConditional() && "If unconditional, it can't be in loop!")((BI->isConditional() && "If unconditional, it can't be in loop!" ) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"If unconditional, it can't be in loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7090, __PRETTY_FUNCTION__)); |
7091 | bool ExitIfTrue = !L->contains(BI->getSuccessor(0)); |
7092 | assert(ExitIfTrue == L->contains(BI->getSuccessor(1)) &&((ExitIfTrue == L->contains(BI->getSuccessor(1)) && "It should have one successor in loop and one exit block!") ? static_cast<void> (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7093, __PRETTY_FUNCTION__)) |
7093 | "It should have one successor in loop and one exit block!")((ExitIfTrue == L->contains(BI->getSuccessor(1)) && "It should have one successor in loop and one exit block!") ? static_cast<void> (0) : __assert_fail ("ExitIfTrue == L->contains(BI->getSuccessor(1)) && \"It should have one successor in loop and one exit block!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7093, __PRETTY_FUNCTION__)); |
7094 | // Proceed to the next level to examine the exit condition expression. |
7095 | return computeExitLimitFromCond( |
7096 | L, BI->getCondition(), ExitIfTrue, |
7097 | /*ControlsExit=*/IsOnlyExit, AllowPredicates); |
7098 | } |
7099 | |
7100 | if (SwitchInst *SI = dyn_cast<SwitchInst>(Term)) { |
7101 | // For switch, make sure that there is a single exit from the loop. |
7102 | BasicBlock *Exit = nullptr; |
7103 | for (auto *SBB : successors(ExitingBlock)) |
7104 | if (!L->contains(SBB)) { |
7105 | if (Exit) // Multiple exit successors. |
7106 | return getCouldNotCompute(); |
7107 | Exit = SBB; |
7108 | } |
7109 | assert(Exit && "Exiting block must have at least one exit")((Exit && "Exiting block must have at least one exit" ) ? static_cast<void> (0) : __assert_fail ("Exit && \"Exiting block must have at least one exit\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7109, __PRETTY_FUNCTION__)); |
7110 | return computeExitLimitFromSingleExitSwitch(L, SI, Exit, |
7111 | /*ControlsExit=*/IsOnlyExit); |
7112 | } |
7113 | |
7114 | return getCouldNotCompute(); |
7115 | } |
7116 | |
7117 | ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond( |
7118 | const Loop *L, Value *ExitCond, bool ExitIfTrue, |
7119 | bool ControlsExit, bool AllowPredicates) { |
7120 | ScalarEvolution::ExitLimitCacheTy Cache(L, ExitIfTrue, AllowPredicates); |
7121 | return computeExitLimitFromCondCached(Cache, L, ExitCond, ExitIfTrue, |
7122 | ControlsExit, AllowPredicates); |
7123 | } |
7124 | |
7125 | Optional<ScalarEvolution::ExitLimit> |
7126 | ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond, |
7127 | bool ExitIfTrue, bool ControlsExit, |
7128 | bool AllowPredicates) { |
7129 | (void)this->L; |
7130 | (void)this->ExitIfTrue; |
7131 | (void)this->AllowPredicates; |
7132 | |
7133 | assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7135, __PRETTY_FUNCTION__)) |
7134 | this->AllowPredicates == AllowPredicates &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7135, __PRETTY_FUNCTION__)) |
7135 | "Variance in assumed invariant key components!")((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7135, __PRETTY_FUNCTION__)); |
7136 | auto Itr = TripCountMap.find({ExitCond, ControlsExit}); |
7137 | if (Itr == TripCountMap.end()) |
7138 | return None; |
7139 | return Itr->second; |
7140 | } |
7141 | |
7142 | void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond, |
7143 | bool ExitIfTrue, |
7144 | bool ControlsExit, |
7145 | bool AllowPredicates, |
7146 | const ExitLimit &EL) { |
7147 | assert(this->L == L && this->ExitIfTrue == ExitIfTrue &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7149, __PRETTY_FUNCTION__)) |
7148 | this->AllowPredicates == AllowPredicates &&((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7149, __PRETTY_FUNCTION__)) |
7149 | "Variance in assumed invariant key components!")((this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && "Variance in assumed invariant key components!") ? static_cast <void> (0) : __assert_fail ("this->L == L && this->ExitIfTrue == ExitIfTrue && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7149, __PRETTY_FUNCTION__)); |
7150 | |
7151 | auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL}); |
7152 | assert(InsertResult.second && "Expected successful insertion!")((InsertResult.second && "Expected successful insertion!" ) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expected successful insertion!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7152, __PRETTY_FUNCTION__)); |
7153 | (void)InsertResult; |
7154 | (void)ExitIfTrue; |
7155 | } |
7156 | |
7157 | ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached( |
7158 | ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue, |
7159 | bool ControlsExit, bool AllowPredicates) { |
7160 | |
7161 | if (auto MaybeEL = |
7162 | Cache.find(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates)) |
7163 | return *MaybeEL; |
7164 | |
7165 | ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, ExitIfTrue, |
7166 | ControlsExit, AllowPredicates); |
7167 | Cache.insert(L, ExitCond, ExitIfTrue, ControlsExit, AllowPredicates, EL); |
7168 | return EL; |
7169 | } |
7170 | |
7171 | ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl( |
7172 | ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, bool ExitIfTrue, |
7173 | bool ControlsExit, bool AllowPredicates) { |
7174 | // Check if the controlling expression for this loop is an And or Or. |
7175 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) { |
7176 | if (BO->getOpcode() == Instruction::And) { |
7177 | // Recurse on the operands of the and. |
7178 | bool EitherMayExit = !ExitIfTrue; |
7179 | ExitLimit EL0 = computeExitLimitFromCondCached( |
7180 | Cache, L, BO->getOperand(0), ExitIfTrue, |
7181 | ControlsExit && !EitherMayExit, AllowPredicates); |
7182 | ExitLimit EL1 = computeExitLimitFromCondCached( |
7183 | Cache, L, BO->getOperand(1), ExitIfTrue, |
7184 | ControlsExit && !EitherMayExit, AllowPredicates); |
7185 | const SCEV *BECount = getCouldNotCompute(); |
7186 | const SCEV *MaxBECount = getCouldNotCompute(); |
7187 | if (EitherMayExit) { |
7188 | // Both conditions must be true for the loop to continue executing. |
7189 | // Choose the less conservative count. |
7190 | if (EL0.ExactNotTaken == getCouldNotCompute() || |
7191 | EL1.ExactNotTaken == getCouldNotCompute()) |
7192 | BECount = getCouldNotCompute(); |
7193 | else |
7194 | BECount = |
7195 | getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken); |
7196 | if (EL0.MaxNotTaken == getCouldNotCompute()) |
7197 | MaxBECount = EL1.MaxNotTaken; |
7198 | else if (EL1.MaxNotTaken == getCouldNotCompute()) |
7199 | MaxBECount = EL0.MaxNotTaken; |
7200 | else |
7201 | MaxBECount = |
7202 | getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken); |
7203 | } else { |
7204 | // Both conditions must be true at the same time for the loop to exit. |
7205 | // For now, be conservative. |
7206 | if (EL0.MaxNotTaken == EL1.MaxNotTaken) |
7207 | MaxBECount = EL0.MaxNotTaken; |
7208 | if (EL0.ExactNotTaken == EL1.ExactNotTaken) |
7209 | BECount = EL0.ExactNotTaken; |
7210 | } |
7211 | |
7212 | // There are cases (e.g. PR26207) where computeExitLimitFromCond is able |
7213 | // to be more aggressive when computing BECount than when computing |
7214 | // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and |
7215 | // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken |
7216 | // to not. |
7217 | if (isa<SCEVCouldNotCompute>(MaxBECount) && |
7218 | !isa<SCEVCouldNotCompute>(BECount)) |
7219 | MaxBECount = getConstant(getUnsignedRangeMax(BECount)); |
7220 | |
7221 | return ExitLimit(BECount, MaxBECount, false, |
7222 | {&EL0.Predicates, &EL1.Predicates}); |
7223 | } |
7224 | if (BO->getOpcode() == Instruction::Or) { |
7225 | // Recurse on the operands of the or. |
7226 | bool EitherMayExit = ExitIfTrue; |
7227 | ExitLimit EL0 = computeExitLimitFromCondCached( |
7228 | Cache, L, BO->getOperand(0), ExitIfTrue, |
7229 | ControlsExit && !EitherMayExit, AllowPredicates); |
7230 | ExitLimit EL1 = computeExitLimitFromCondCached( |
7231 | Cache, L, BO->getOperand(1), ExitIfTrue, |
7232 | ControlsExit && !EitherMayExit, AllowPredicates); |
7233 | const SCEV *BECount = getCouldNotCompute(); |
7234 | const SCEV *MaxBECount = getCouldNotCompute(); |
7235 | if (EitherMayExit) { |
7236 | // Both conditions must be false for the loop to continue executing. |
7237 | // Choose the less conservative count. |
7238 | if (EL0.ExactNotTaken == getCouldNotCompute() || |
7239 | EL1.ExactNotTaken == getCouldNotCompute()) |
7240 | BECount = getCouldNotCompute(); |
7241 | else |
7242 | BECount = |
7243 | getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken); |
7244 | if (EL0.MaxNotTaken == getCouldNotCompute()) |
7245 | MaxBECount = EL1.MaxNotTaken; |
7246 | else if (EL1.MaxNotTaken == getCouldNotCompute()) |
7247 | MaxBECount = EL0.MaxNotTaken; |
7248 | else |
7249 | MaxBECount = |
7250 | getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken); |
7251 | } else { |
7252 | // Both conditions must be false at the same time for the loop to exit. |
7253 | // For now, be conservative. |
7254 | if (EL0.MaxNotTaken == EL1.MaxNotTaken) |
7255 | MaxBECount = EL0.MaxNotTaken; |
7256 | if (EL0.ExactNotTaken == EL1.ExactNotTaken) |
7257 | BECount = EL0.ExactNotTaken; |
7258 | } |
7259 | |
7260 | return ExitLimit(BECount, MaxBECount, false, |
7261 | {&EL0.Predicates, &EL1.Predicates}); |
7262 | } |
7263 | } |
7264 | |
7265 | // With an icmp, it may be feasible to compute an exact backedge-taken count. |
7266 | // Proceed to the next level to examine the icmp. |
7267 | if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) { |
7268 | ExitLimit EL = |
7269 | computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit); |
7270 | if (EL.hasFullInfo() || !AllowPredicates) |
7271 | return EL; |
7272 | |
7273 | // Try again, but use SCEV predicates this time. |
7274 | return computeExitLimitFromICmp(L, ExitCondICmp, ExitIfTrue, ControlsExit, |
7275 | /*AllowPredicates=*/true); |
7276 | } |
7277 | |
7278 | // Check for a constant condition. These are normally stripped out by |
7279 | // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to |
7280 | // preserve the CFG and is temporarily leaving constant conditions |
7281 | // in place. |
7282 | if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) { |
7283 | if (ExitIfTrue == !CI->getZExtValue()) |
7284 | // The backedge is always taken. |
7285 | return getCouldNotCompute(); |
7286 | else |
7287 | // The backedge is never taken. |
7288 | return getZero(CI->getType()); |
7289 | } |
7290 | |
7291 | // If it's not an integer or pointer comparison then compute it the hard way. |
7292 | return computeExitCountExhaustively(L, ExitCond, ExitIfTrue); |
7293 | } |
7294 | |
7295 | ScalarEvolution::ExitLimit |
7296 | ScalarEvolution::computeExitLimitFromICmp(const Loop *L, |
7297 | ICmpInst *ExitCond, |
7298 | bool ExitIfTrue, |
7299 | bool ControlsExit, |
7300 | bool AllowPredicates) { |
7301 | // If the condition was exit on true, convert the condition to exit on false |
7302 | ICmpInst::Predicate Pred; |
7303 | if (!ExitIfTrue) |
7304 | Pred = ExitCond->getPredicate(); |
7305 | else |
7306 | Pred = ExitCond->getInversePredicate(); |
7307 | const ICmpInst::Predicate OriginalPred = Pred; |
7308 | |
7309 | // Handle common loops like: for (X = "string"; *X; ++X) |
7310 | if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0))) |
7311 | if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) { |
7312 | ExitLimit ItCnt = |
7313 | computeLoadConstantCompareExitLimit(LI, RHS, L, Pred); |
7314 | if (ItCnt.hasAnyInfo()) |
7315 | return ItCnt; |
7316 | } |
7317 | |
7318 | const SCEV *LHS = getSCEV(ExitCond->getOperand(0)); |
7319 | const SCEV *RHS = getSCEV(ExitCond->getOperand(1)); |
7320 | |
7321 | // Try to evaluate any dependencies out of the loop. |
7322 | LHS = getSCEVAtScope(LHS, L); |
7323 | RHS = getSCEVAtScope(RHS, L); |
7324 | |
7325 | // At this point, we would like to compute how many iterations of the |
7326 | // loop the predicate will return true for these inputs. |
7327 | if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) { |
7328 | // If there is a loop-invariant, force it into the RHS. |
7329 | std::swap(LHS, RHS); |
7330 | Pred = ICmpInst::getSwappedPredicate(Pred); |
7331 | } |
7332 | |
7333 | // Simplify the operands before analyzing them. |
7334 | (void)SimplifyICmpOperands(Pred, LHS, RHS); |
7335 | |
7336 | // If we have a comparison of a chrec against a constant, try to use value |
7337 | // ranges to answer this query. |
7338 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) |
7339 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS)) |
7340 | if (AddRec->getLoop() == L) { |
7341 | // Form the constant range. |
7342 | ConstantRange CompRange = |
7343 | ConstantRange::makeExactICmpRegion(Pred, RHSC->getAPInt()); |
7344 | |
7345 | const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this); |
7346 | if (!isa<SCEVCouldNotCompute>(Ret)) return Ret; |
7347 | } |
7348 | |
7349 | switch (Pred) { |
7350 | case ICmpInst::ICMP_NE: { // while (X != Y) |
7351 | // Convert to: while (X-Y != 0) |
7352 | ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit, |
7353 | AllowPredicates); |
7354 | if (EL.hasAnyInfo()) return EL; |
7355 | break; |
7356 | } |
7357 | case ICmpInst::ICMP_EQ: { // while (X == Y) |
7358 | // Convert to: while (X-Y == 0) |
7359 | ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L); |
7360 | if (EL.hasAnyInfo()) return EL; |
7361 | break; |
7362 | } |
7363 | case ICmpInst::ICMP_SLT: |
7364 | case ICmpInst::ICMP_ULT: { // while (X < Y) |
7365 | bool IsSigned = Pred == ICmpInst::ICMP_SLT; |
7366 | ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit, |
7367 | AllowPredicates); |
7368 | if (EL.hasAnyInfo()) return EL; |
7369 | break; |
7370 | } |
7371 | case ICmpInst::ICMP_SGT: |
7372 | case ICmpInst::ICMP_UGT: { // while (X > Y) |
7373 | bool IsSigned = Pred == ICmpInst::ICMP_SGT; |
7374 | ExitLimit EL = |
7375 | howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit, |
7376 | AllowPredicates); |
7377 | if (EL.hasAnyInfo()) return EL; |
7378 | break; |
7379 | } |
7380 | default: |
7381 | break; |
7382 | } |
7383 | |
7384 | auto *ExhaustiveCount = |
7385 | computeExitCountExhaustively(L, ExitCond, ExitIfTrue); |
7386 | |
7387 | if (!isa<SCEVCouldNotCompute>(ExhaustiveCount)) |
7388 | return ExhaustiveCount; |
7389 | |
7390 | return computeShiftCompareExitLimit(ExitCond->getOperand(0), |
7391 | ExitCond->getOperand(1), L, OriginalPred); |
7392 | } |
7393 | |
7394 | ScalarEvolution::ExitLimit |
7395 | ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L, |
7396 | SwitchInst *Switch, |
7397 | BasicBlock *ExitingBlock, |
7398 | bool ControlsExit) { |
7399 | assert(!L->contains(ExitingBlock) && "Not an exiting block!")((!L->contains(ExitingBlock) && "Not an exiting block!" ) ? static_cast<void> (0) : __assert_fail ("!L->contains(ExitingBlock) && \"Not an exiting block!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7399, __PRETTY_FUNCTION__)); |
7400 | |
7401 | // Give up if the exit is the default dest of a switch. |
7402 | if (Switch->getDefaultDest() == ExitingBlock) |
7403 | return getCouldNotCompute(); |
7404 | |
7405 | assert(L->contains(Switch->getDefaultDest()) &&((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7406, __PRETTY_FUNCTION__)) |
7406 | "Default case must not exit the loop!")((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!" ) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7406, __PRETTY_FUNCTION__)); |
7407 | const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L); |
7408 | const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock)); |
7409 | |
7410 | // while (X != Y) --> while (X-Y != 0) |
7411 | ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit); |
7412 | if (EL.hasAnyInfo()) |
7413 | return EL; |
7414 | |
7415 | return getCouldNotCompute(); |
7416 | } |
7417 | |
7418 | static ConstantInt * |
7419 | EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C, |
7420 | ScalarEvolution &SE) { |
7421 | const SCEV *InVal = SE.getConstant(C); |
7422 | const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE); |
7423 | assert(isa<SCEVConstant>(Val) &&((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7424, __PRETTY_FUNCTION__)) |
7424 | "Evaluation of SCEV at constant didn't fold correctly?")((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?" ) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7424, __PRETTY_FUNCTION__)); |
7425 | return cast<SCEVConstant>(Val)->getValue(); |
7426 | } |
7427 | |
7428 | /// Given an exit condition of 'icmp op load X, cst', try to see if we can |
7429 | /// compute the backedge execution count. |
7430 | ScalarEvolution::ExitLimit |
7431 | ScalarEvolution::computeLoadConstantCompareExitLimit( |
7432 | LoadInst *LI, |
7433 | Constant *RHS, |
7434 | const Loop *L, |
7435 | ICmpInst::Predicate predicate) { |
7436 | if (LI->isVolatile()) return getCouldNotCompute(); |
7437 | |
7438 | // Check to see if the loaded pointer is a getelementptr of a global. |
7439 | // TODO: Use SCEV instead of manually grubbing with GEPs. |
7440 | GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)); |
7441 | if (!GEP) return getCouldNotCompute(); |
7442 | |
7443 | // Make sure that it is really a constant global we are gepping, with an |
7444 | // initializer, and make sure the first IDX is really 0. |
7445 | GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)); |
7446 | if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() || |
7447 | GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) || |
7448 | !cast<Constant>(GEP->getOperand(1))->isNullValue()) |
7449 | return getCouldNotCompute(); |
7450 | |
7451 | // Okay, we allow one non-constant index into the GEP instruction. |
7452 | Value *VarIdx = nullptr; |
7453 | std::vector<Constant*> Indexes; |
7454 | unsigned VarIdxNum = 0; |
7455 | for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i) |
7456 | if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { |
7457 | Indexes.push_back(CI); |
7458 | } else if (!isa<ConstantInt>(GEP->getOperand(i))) { |
7459 | if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's. |
7460 | VarIdx = GEP->getOperand(i); |
7461 | VarIdxNum = i-2; |
7462 | Indexes.push_back(nullptr); |
7463 | } |
7464 | |
7465 | // Loop-invariant loads may be a byproduct of loop optimization. Skip them. |
7466 | if (!VarIdx) |
7467 | return getCouldNotCompute(); |
7468 | |
7469 | // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant. |
7470 | // Check to see if X is a loop variant variable value now. |
7471 | const SCEV *Idx = getSCEV(VarIdx); |
7472 | Idx = getSCEVAtScope(Idx, L); |
7473 | |
7474 | // We can only recognize very limited forms of loop index expressions, in |
7475 | // particular, only affine AddRec's like {C1,+,C2}. |
7476 | const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx); |
7477 | if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) || |
7478 | !isa<SCEVConstant>(IdxExpr->getOperand(0)) || |
7479 | !isa<SCEVConstant>(IdxExpr->getOperand(1))) |
7480 | return getCouldNotCompute(); |
7481 | |
7482 | unsigned MaxSteps = MaxBruteForceIterations; |
7483 | for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) { |
7484 | ConstantInt *ItCst = ConstantInt::get( |
7485 | cast<IntegerType>(IdxExpr->getType()), IterationNum); |
7486 | ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this); |
7487 | |
7488 | // Form the GEP offset. |
7489 | Indexes[VarIdxNum] = Val; |
7490 | |
7491 | Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(), |
7492 | Indexes); |
7493 | if (!Result) break; // Cannot compute! |
7494 | |
7495 | // Evaluate the condition for this iteration. |
7496 | Result = ConstantExpr::getICmp(predicate, Result, RHS); |
7497 | if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure |
7498 | if (cast<ConstantInt>(Result)->getValue().isMinValue()) { |
7499 | ++NumArrayLenItCounts; |
7500 | return getConstant(ItCst); // Found terminating iteration! |
7501 | } |
7502 | } |
7503 | return getCouldNotCompute(); |
7504 | } |
7505 | |
7506 | ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit( |
7507 | Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) { |
7508 | ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV); |
7509 | if (!RHS) |
7510 | return getCouldNotCompute(); |
7511 | |
7512 | const BasicBlock *Latch = L->getLoopLatch(); |
7513 | if (!Latch) |
7514 | return getCouldNotCompute(); |
7515 | |
7516 | const BasicBlock *Predecessor = L->getLoopPredecessor(); |
7517 | if (!Predecessor) |
7518 | return getCouldNotCompute(); |
7519 | |
7520 | // Return true if V is of the form "LHS `shift_op` <positive constant>". |
7521 | // Return LHS in OutLHS and shift_opt in OutOpCode. |
7522 | auto MatchPositiveShift = |
7523 | [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) { |
7524 | |
7525 | using namespace PatternMatch; |
7526 | |
7527 | ConstantInt *ShiftAmt; |
7528 | if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) |
7529 | OutOpCode = Instruction::LShr; |
7530 | else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) |
7531 | OutOpCode = Instruction::AShr; |
7532 | else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt)))) |
7533 | OutOpCode = Instruction::Shl; |
7534 | else |
7535 | return false; |
7536 | |
7537 | return ShiftAmt->getValue().isStrictlyPositive(); |
7538 | }; |
7539 | |
7540 | // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in |
7541 | // |
7542 | // loop: |
7543 | // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ] |
7544 | // %iv.shifted = lshr i32 %iv, <positive constant> |
7545 | // |
7546 | // Return true on a successful match. Return the corresponding PHI node (%iv |
7547 | // above) in PNOut and the opcode of the shift operation in OpCodeOut. |
7548 | auto MatchShiftRecurrence = |
7549 | [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) { |
7550 | Optional<Instruction::BinaryOps> PostShiftOpCode; |
7551 | |
7552 | { |
7553 | Instruction::BinaryOps OpC; |
7554 | Value *V; |
7555 | |
7556 | // If we encounter a shift instruction, "peel off" the shift operation, |
7557 | // and remember that we did so. Later when we inspect %iv's backedge |
7558 | // value, we will make sure that the backedge value uses the same |
7559 | // operation. |
7560 | // |
7561 | // Note: the peeled shift operation does not have to be the same |
7562 | // instruction as the one feeding into the PHI's backedge value. We only |
7563 | // really care about it being the same *kind* of shift instruction -- |
7564 | // that's all that is required for our later inferences to hold. |
7565 | if (MatchPositiveShift(LHS, V, OpC)) { |
7566 | PostShiftOpCode = OpC; |
7567 | LHS = V; |
7568 | } |
7569 | } |
7570 | |
7571 | PNOut = dyn_cast<PHINode>(LHS); |
7572 | if (!PNOut || PNOut->getParent() != L->getHeader()) |
7573 | return false; |
7574 | |
7575 | Value *BEValue = PNOut->getIncomingValueForBlock(Latch); |
7576 | Value *OpLHS; |
7577 | |
7578 | return |
7579 | // The backedge value for the PHI node must be a shift by a positive |
7580 | // amount |
7581 | MatchPositiveShift(BEValue, OpLHS, OpCodeOut) && |
7582 | |
7583 | // of the PHI node itself |
7584 | OpLHS == PNOut && |
7585 | |
7586 | // and the kind of shift should be match the kind of shift we peeled |
7587 | // off, if any. |
7588 | (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut); |
7589 | }; |
7590 | |
7591 | PHINode *PN; |
7592 | Instruction::BinaryOps OpCode; |
7593 | if (!MatchShiftRecurrence(LHS, PN, OpCode)) |
7594 | return getCouldNotCompute(); |
7595 | |
7596 | const DataLayout &DL = getDataLayout(); |
7597 | |
7598 | // The key rationale for this optimization is that for some kinds of shift |
7599 | // recurrences, the value of the recurrence "stabilizes" to either 0 or -1 |
7600 | // within a finite number of iterations. If the condition guarding the |
7601 | // backedge (in the sense that the backedge is taken if the condition is true) |
7602 | // is false for the value the shift recurrence stabilizes to, then we know |
7603 | // that the backedge is taken only a finite number of times. |
7604 | |
7605 | ConstantInt *StableValue = nullptr; |
7606 | switch (OpCode) { |
7607 | default: |
7608 | llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7608); |
7609 | |
7610 | case Instruction::AShr: { |
7611 | // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most |
7612 | // bitwidth(K) iterations. |
7613 | Value *FirstValue = PN->getIncomingValueForBlock(Predecessor); |
7614 | KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr, |
7615 | Predecessor->getTerminator(), &DT); |
7616 | auto *Ty = cast<IntegerType>(RHS->getType()); |
7617 | if (Known.isNonNegative()) |
7618 | StableValue = ConstantInt::get(Ty, 0); |
7619 | else if (Known.isNegative()) |
7620 | StableValue = ConstantInt::get(Ty, -1, true); |
7621 | else |
7622 | return getCouldNotCompute(); |
7623 | |
7624 | break; |
7625 | } |
7626 | case Instruction::LShr: |
7627 | case Instruction::Shl: |
7628 | // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>} |
7629 | // stabilize to 0 in at most bitwidth(K) iterations. |
7630 | StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0); |
7631 | break; |
7632 | } |
7633 | |
7634 | auto *Result = |
7635 | ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI); |
7636 | assert(Result->getType()->isIntegerTy(1) &&((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction" ) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7637, __PRETTY_FUNCTION__)) |
7637 | "Otherwise cannot be an operand to a branch instruction")((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction" ) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7637, __PRETTY_FUNCTION__)); |
7638 | |
7639 | if (Result->isZeroValue()) { |
7640 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); |
7641 | const SCEV *UpperBound = |
7642 | getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth); |
7643 | return ExitLimit(getCouldNotCompute(), UpperBound, false); |
7644 | } |
7645 | |
7646 | return getCouldNotCompute(); |
7647 | } |
7648 | |
7649 | /// Return true if we can constant fold an instruction of the specified type, |
7650 | /// assuming that all operands were constants. |
7651 | static bool CanConstantFold(const Instruction *I) { |
7652 | if (isa<BinaryOperator>(I) || isa<CmpInst>(I) || |
7653 | isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) || |
7654 | isa<LoadInst>(I)) |
7655 | return true; |
7656 | |
7657 | if (const CallInst *CI = dyn_cast<CallInst>(I)) |
7658 | if (const Function *F = CI->getCalledFunction()) |
7659 | return canConstantFoldCallTo(CI, F); |
7660 | return false; |
7661 | } |
7662 | |
7663 | /// Determine whether this instruction can constant evolve within this loop |
7664 | /// assuming its operands can all constant evolve. |
7665 | static bool canConstantEvolve(Instruction *I, const Loop *L) { |
7666 | // An instruction outside of the loop can't be derived from a loop PHI. |
7667 | if (!L->contains(I)) return false; |
7668 | |
7669 | if (isa<PHINode>(I)) { |
7670 | // We don't currently keep track of the control flow needed to evaluate |
7671 | // PHIs, so we cannot handle PHIs inside of loops. |
7672 | return L->getHeader() == I->getParent(); |
7673 | } |
7674 | |
7675 | // If we won't be able to constant fold this expression even if the operands |
7676 | // are constants, bail early. |
7677 | return CanConstantFold(I); |
7678 | } |
7679 | |
7680 | /// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by |
7681 | /// recursing through each instruction operand until reaching a loop header phi. |
7682 | static PHINode * |
7683 | getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L, |
7684 | DenseMap<Instruction *, PHINode *> &PHIMap, |
7685 | unsigned Depth) { |
7686 | if (Depth > MaxConstantEvolvingDepth) |
7687 | return nullptr; |
7688 | |
7689 | // Otherwise, we can evaluate this instruction if all of its operands are |
7690 | // constant or derived from a PHI node themselves. |
7691 | PHINode *PHI = nullptr; |
7692 | for (Value *Op : UseInst->operands()) { |
7693 | if (isa<Constant>(Op)) continue; |
7694 | |
7695 | Instruction *OpInst = dyn_cast<Instruction>(Op); |
7696 | if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr; |
7697 | |
7698 | PHINode *P = dyn_cast<PHINode>(OpInst); |
7699 | if (!P) |
7700 | // If this operand is already visited, reuse the prior result. |
7701 | // We may have P != PHI if this is the deepest point at which the |
7702 | // inconsistent paths meet. |
7703 | P = PHIMap.lookup(OpInst); |
7704 | if (!P) { |
7705 | // Recurse and memoize the results, whether a phi is found or not. |
7706 | // This recursive call invalidates pointers into PHIMap. |
7707 | P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1); |
7708 | PHIMap[OpInst] = P; |
7709 | } |
7710 | if (!P) |
7711 | return nullptr; // Not evolving from PHI |
7712 | if (PHI && PHI != P) |
7713 | return nullptr; // Evolving from multiple different PHIs. |
7714 | PHI = P; |
7715 | } |
7716 | // This is a expression evolving from a constant PHI! |
7717 | return PHI; |
7718 | } |
7719 | |
7720 | /// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node |
7721 | /// in the loop that V is derived from. We allow arbitrary operations along the |
7722 | /// way, but the operands of an operation must either be constants or a value |
7723 | /// derived from a constant PHI. If this expression does not fit with these |
7724 | /// constraints, return null. |
7725 | static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) { |
7726 | Instruction *I = dyn_cast<Instruction>(V); |
7727 | if (!I || !canConstantEvolve(I, L)) return nullptr; |
7728 | |
7729 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
7730 | return PN; |
7731 | |
7732 | // Record non-constant instructions contained by the loop. |
7733 | DenseMap<Instruction *, PHINode *> PHIMap; |
7734 | return getConstantEvolvingPHIOperands(I, L, PHIMap, 0); |
7735 | } |
7736 | |
7737 | /// EvaluateExpression - Given an expression that passes the |
7738 | /// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node |
7739 | /// in the loop has the value PHIVal. If we can't fold this expression for some |
7740 | /// reason, return null. |
7741 | static Constant *EvaluateExpression(Value *V, const Loop *L, |
7742 | DenseMap<Instruction *, Constant *> &Vals, |
7743 | const DataLayout &DL, |
7744 | const TargetLibraryInfo *TLI) { |
7745 | // Convenient constant check, but redundant for recursive calls. |
7746 | if (Constant *C = dyn_cast<Constant>(V)) return C; |
7747 | Instruction *I = dyn_cast<Instruction>(V); |
7748 | if (!I) return nullptr; |
7749 | |
7750 | if (Constant *C = Vals.lookup(I)) return C; |
7751 | |
7752 | // An instruction inside the loop depends on a value outside the loop that we |
7753 | // weren't given a mapping for, or a value such as a call inside the loop. |
7754 | if (!canConstantEvolve(I, L)) return nullptr; |
7755 | |
7756 | // An unmapped PHI can be due to a branch or another loop inside this loop, |
7757 | // or due to this not being the initial iteration through a loop where we |
7758 | // couldn't compute the evolution of this particular PHI last time. |
7759 | if (isa<PHINode>(I)) return nullptr; |
7760 | |
7761 | std::vector<Constant*> Operands(I->getNumOperands()); |
7762 | |
7763 | for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { |
7764 | Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i)); |
7765 | if (!Operand) { |
7766 | Operands[i] = dyn_cast<Constant>(I->getOperand(i)); |
7767 | if (!Operands[i]) return nullptr; |
7768 | continue; |
7769 | } |
7770 | Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI); |
7771 | Vals[Operand] = C; |
7772 | if (!C) return nullptr; |
7773 | Operands[i] = C; |
7774 | } |
7775 | |
7776 | if (CmpInst *CI = dyn_cast<CmpInst>(I)) |
7777 | return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0], |
7778 | Operands[1], DL, TLI); |
7779 | if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
7780 | if (!LI->isVolatile()) |
7781 | return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL); |
7782 | } |
7783 | return ConstantFoldInstOperands(I, Operands, DL, TLI); |
7784 | } |
7785 | |
7786 | |
7787 | // If every incoming value to PN except the one for BB is a specific Constant, |
7788 | // return that, else return nullptr. |
7789 | static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) { |
7790 | Constant *IncomingVal = nullptr; |
7791 | |
7792 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
7793 | if (PN->getIncomingBlock(i) == BB) |
7794 | continue; |
7795 | |
7796 | auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i)); |
7797 | if (!CurrentVal) |
7798 | return nullptr; |
7799 | |
7800 | if (IncomingVal != CurrentVal) { |
7801 | if (IncomingVal) |
7802 | return nullptr; |
7803 | IncomingVal = CurrentVal; |
7804 | } |
7805 | } |
7806 | |
7807 | return IncomingVal; |
7808 | } |
7809 | |
7810 | /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is |
7811 | /// in the header of its containing loop, we know the loop executes a |
7812 | /// constant number of times, and the PHI node is just a recurrence |
7813 | /// involving constants, fold it. |
7814 | Constant * |
7815 | ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN, |
7816 | const APInt &BEs, |
7817 | const Loop *L) { |
7818 | auto I = ConstantEvolutionLoopExitValue.find(PN); |
7819 | if (I != ConstantEvolutionLoopExitValue.end()) |
7820 | return I->second; |
7821 | |
7822 | if (BEs.ugt(MaxBruteForceIterations)) |
7823 | return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it. |
7824 | |
7825 | Constant *&RetVal = ConstantEvolutionLoopExitValue[PN]; |
7826 | |
7827 | DenseMap<Instruction *, Constant *> CurrentIterVals; |
7828 | BasicBlock *Header = L->getHeader(); |
7829 | assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!" ) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7829, __PRETTY_FUNCTION__)); |
7830 | |
7831 | BasicBlock *Latch = L->getLoopLatch(); |
7832 | if (!Latch) |
7833 | return nullptr; |
7834 | |
7835 | for (PHINode &PHI : Header->phis()) { |
7836 | if (auto *StartCST = getOtherIncomingValue(&PHI, Latch)) |
7837 | CurrentIterVals[&PHI] = StartCST; |
7838 | } |
7839 | if (!CurrentIterVals.count(PN)) |
7840 | return RetVal = nullptr; |
7841 | |
7842 | Value *BEValue = PN->getIncomingValueForBlock(Latch); |
7843 | |
7844 | // Execute the loop symbolically to determine the exit value. |
7845 | assert(BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) &&((BEs.getActiveBits() < 8 * sizeof(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!" ) ? static_cast<void> (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7846, __PRETTY_FUNCTION__)) |
7846 | "BEs is <= MaxBruteForceIterations which is an 'unsigned'!")((BEs.getActiveBits() < 8 * sizeof(unsigned) && "BEs is <= MaxBruteForceIterations which is an 'unsigned'!" ) ? static_cast<void> (0) : __assert_fail ("BEs.getActiveBits() < CHAR_BIT * sizeof(unsigned) && \"BEs is <= MaxBruteForceIterations which is an 'unsigned'!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7846, __PRETTY_FUNCTION__)); |
7847 | |
7848 | unsigned NumIterations = BEs.getZExtValue(); // must be in range |
7849 | unsigned IterationNum = 0; |
7850 | const DataLayout &DL = getDataLayout(); |
7851 | for (; ; ++IterationNum) { |
7852 | if (IterationNum == NumIterations) |
7853 | return RetVal = CurrentIterVals[PN]; // Got exit value! |
7854 | |
7855 | // Compute the value of the PHIs for the next iteration. |
7856 | // EvaluateExpression adds non-phi values to the CurrentIterVals map. |
7857 | DenseMap<Instruction *, Constant *> NextIterVals; |
7858 | Constant *NextPHI = |
7859 | EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); |
7860 | if (!NextPHI) |
7861 | return nullptr; // Couldn't evaluate! |
7862 | NextIterVals[PN] = NextPHI; |
7863 | |
7864 | bool StoppedEvolving = NextPHI == CurrentIterVals[PN]; |
7865 | |
7866 | // Also evaluate the other PHI nodes. However, we don't get to stop if we |
7867 | // cease to be able to evaluate one of them or if they stop evolving, |
7868 | // because that doesn't necessarily prevent us from computing PN. |
7869 | SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute; |
7870 | for (const auto &I : CurrentIterVals) { |
7871 | PHINode *PHI = dyn_cast<PHINode>(I.first); |
7872 | if (!PHI || PHI == PN || PHI->getParent() != Header) continue; |
7873 | PHIsToCompute.emplace_back(PHI, I.second); |
7874 | } |
7875 | // We use two distinct loops because EvaluateExpression may invalidate any |
7876 | // iterators into CurrentIterVals. |
7877 | for (const auto &I : PHIsToCompute) { |
7878 | PHINode *PHI = I.first; |
7879 | Constant *&NextPHI = NextIterVals[PHI]; |
7880 | if (!NextPHI) { // Not already computed. |
7881 | Value *BEValue = PHI->getIncomingValueForBlock(Latch); |
7882 | NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); |
7883 | } |
7884 | if (NextPHI != I.second) |
7885 | StoppedEvolving = false; |
7886 | } |
7887 | |
7888 | // If all entries in CurrentIterVals == NextIterVals then we can stop |
7889 | // iterating, the loop can't continue to change. |
7890 | if (StoppedEvolving) |
7891 | return RetVal = CurrentIterVals[PN]; |
7892 | |
7893 | CurrentIterVals.swap(NextIterVals); |
7894 | } |
7895 | } |
7896 | |
7897 | const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L, |
7898 | Value *Cond, |
7899 | bool ExitWhen) { |
7900 | PHINode *PN = getConstantEvolvingPHI(Cond, L); |
7901 | if (!PN) return getCouldNotCompute(); |
7902 | |
7903 | // If the loop is canonicalized, the PHI will have exactly two entries. |
7904 | // That's the only form we support here. |
7905 | if (PN->getNumIncomingValues() != 2) return getCouldNotCompute(); |
7906 | |
7907 | DenseMap<Instruction *, Constant *> CurrentIterVals; |
7908 | BasicBlock *Header = L->getHeader(); |
7909 | assert(PN->getParent() == Header && "Can't evaluate PHI not in loop header!")((PN->getParent() == Header && "Can't evaluate PHI not in loop header!" ) ? static_cast<void> (0) : __assert_fail ("PN->getParent() == Header && \"Can't evaluate PHI not in loop header!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7909, __PRETTY_FUNCTION__)); |
7910 | |
7911 | BasicBlock *Latch = L->getLoopLatch(); |
7912 | assert(Latch && "Should follow from NumIncomingValues == 2!")((Latch && "Should follow from NumIncomingValues == 2!" ) ? static_cast<void> (0) : __assert_fail ("Latch && \"Should follow from NumIncomingValues == 2!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 7912, __PRETTY_FUNCTION__)); |
7913 | |
7914 | for (PHINode &PHI : Header->phis()) { |
7915 | if (auto *StartCST = getOtherIncomingValue(&PHI, Latch)) |
7916 | CurrentIterVals[&PHI] = StartCST; |
7917 | } |
7918 | if (!CurrentIterVals.count(PN)) |
7919 | return getCouldNotCompute(); |
7920 | |
7921 | // Okay, we find a PHI node that defines the trip count of this loop. Execute |
7922 | // the loop symbolically to determine when the condition gets a value of |
7923 | // "ExitWhen". |
7924 | unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis. |
7925 | const DataLayout &DL = getDataLayout(); |
7926 | for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){ |
7927 | auto *CondVal = dyn_cast_or_null<ConstantInt>( |
7928 | EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI)); |
7929 | |
7930 | // Couldn't symbolically evaluate. |
7931 | if (!CondVal) return getCouldNotCompute(); |
7932 | |
7933 | if (CondVal->getValue() == uint64_t(ExitWhen)) { |
7934 | ++NumBruteForceTripCountsComputed; |
7935 | return getConstant(Type::getInt32Ty(getContext()), IterationNum); |
7936 | } |
7937 | |
7938 | // Update all the PHI nodes for the next iteration. |
7939 | DenseMap<Instruction *, Constant *> NextIterVals; |
7940 | |
7941 | // Create a list of which PHIs we need to compute. We want to do this before |
7942 | // calling EvaluateExpression on them because that may invalidate iterators |
7943 | // into CurrentIterVals. |
7944 | SmallVector<PHINode *, 8> PHIsToCompute; |
7945 | for (const auto &I : CurrentIterVals) { |
7946 | PHINode *PHI = dyn_cast<PHINode>(I.first); |
7947 | if (!PHI || PHI->getParent() != Header) continue; |
7948 | PHIsToCompute.push_back(PHI); |
7949 | } |
7950 | for (PHINode *PHI : PHIsToCompute) { |
7951 | Constant *&NextPHI = NextIterVals[PHI]; |
7952 | if (NextPHI) continue; // Already computed! |
7953 | |
7954 | Value *BEValue = PHI->getIncomingValueForBlock(Latch); |
7955 | NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI); |
7956 | } |
7957 | CurrentIterVals.swap(NextIterVals); |
7958 | } |
7959 | |
7960 | // Too many iterations were needed to evaluate. |
7961 | return getCouldNotCompute(); |
7962 | } |
7963 | |
7964 | const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) { |
7965 | SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values = |
7966 | ValuesAtScopes[V]; |
7967 | // Check to see if we've folded this expression at this loop before. |
7968 | for (auto &LS : Values) |
7969 | if (LS.first == L) |
7970 | return LS.second ? LS.second : V; |
7971 | |
7972 | Values.emplace_back(L, nullptr); |
7973 | |
7974 | // Otherwise compute it. |
7975 | const SCEV *C = computeSCEVAtScope(V, L); |
7976 | for (auto &LS : reverse(ValuesAtScopes[V])) |
7977 | if (LS.first == L) { |
7978 | LS.second = C; |
7979 | break; |
7980 | } |
7981 | return C; |
7982 | } |
7983 | |
7984 | /// This builds up a Constant using the ConstantExpr interface. That way, we |
7985 | /// will return Constants for objects which aren't represented by a |
7986 | /// SCEVConstant, because SCEVConstant is restricted to ConstantInt. |
7987 | /// Returns NULL if the SCEV isn't representable as a Constant. |
7988 | static Constant *BuildConstantFromSCEV(const SCEV *V) { |
7989 | switch (static_cast<SCEVTypes>(V->getSCEVType())) { |
7990 | case scCouldNotCompute: |
7991 | case scAddRecExpr: |
7992 | break; |
7993 | case scConstant: |
7994 | return cast<SCEVConstant>(V)->getValue(); |
7995 | case scUnknown: |
7996 | return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue()); |
7997 | case scSignExtend: { |
7998 | const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V); |
7999 | if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand())) |
8000 | return ConstantExpr::getSExt(CastOp, SS->getType()); |
8001 | break; |
8002 | } |
8003 | case scZeroExtend: { |
8004 | const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V); |
8005 | if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand())) |
8006 | return ConstantExpr::getZExt(CastOp, SZ->getType()); |
8007 | break; |
8008 | } |
8009 | case scTruncate: { |
8010 | const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V); |
8011 | if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand())) |
8012 | return ConstantExpr::getTrunc(CastOp, ST->getType()); |
8013 | break; |
8014 | } |
8015 | case scAddExpr: { |
8016 | const SCEVAddExpr *SA = cast<SCEVAddExpr>(V); |
8017 | if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) { |
8018 | if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) { |
8019 | unsigned AS = PTy->getAddressSpace(); |
8020 | Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS); |
8021 | C = ConstantExpr::getBitCast(C, DestPtrTy); |
8022 | } |
8023 | for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) { |
8024 | Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i)); |
8025 | if (!C2) return nullptr; |
8026 | |
8027 | // First pointer! |
8028 | if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) { |
8029 | unsigned AS = C2->getType()->getPointerAddressSpace(); |
8030 | std::swap(C, C2); |
8031 | Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS); |
8032 | // The offsets have been converted to bytes. We can add bytes to an |
8033 | // i8* by GEP with the byte count in the first index. |
8034 | C = ConstantExpr::getBitCast(C, DestPtrTy); |
8035 | } |
8036 | |
8037 | // Don't bother trying to sum two pointers. We probably can't |
8038 | // statically compute a load that results from it anyway. |
8039 | if (C2->getType()->isPointerTy()) |
8040 | return nullptr; |
8041 | |
8042 | if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) { |
8043 | if (PTy->getElementType()->isStructTy()) |
8044 | C2 = ConstantExpr::getIntegerCast( |
8045 | C2, Type::getInt32Ty(C->getContext()), true); |
8046 | C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2); |
8047 | } else |
8048 | C = ConstantExpr::getAdd(C, C2); |
8049 | } |
8050 | return C; |
8051 | } |
8052 | break; |
8053 | } |
8054 | case scMulExpr: { |
8055 | const SCEVMulExpr *SM = cast<SCEVMulExpr>(V); |
8056 | if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) { |
8057 | // Don't bother with pointers at all. |
8058 | if (C->getType()->isPointerTy()) return nullptr; |
8059 | for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) { |
8060 | Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i)); |
8061 | if (!C2 || C2->getType()->isPointerTy()) return nullptr; |
8062 | C = ConstantExpr::getMul(C, C2); |
8063 | } |
8064 | return C; |
8065 | } |
8066 | break; |
8067 | } |
8068 | case scUDivExpr: { |
8069 | const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V); |
8070 | if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS())) |
8071 | if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS())) |
8072 | if (LHS->getType() == RHS->getType()) |
8073 | return ConstantExpr::getUDiv(LHS, RHS); |
8074 | break; |
8075 | } |
8076 | case scSMaxExpr: |
8077 | case scUMaxExpr: |
8078 | break; // TODO: smax, umax. |
8079 | } |
8080 | return nullptr; |
8081 | } |
8082 | |
8083 | const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) { |
8084 | if (isa<SCEVConstant>(V)) return V; |
8085 | |
8086 | // If this instruction is evolved from a constant-evolving PHI, compute the |
8087 | // exit value from the loop without using SCEVs. |
8088 | if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) { |
8089 | if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) { |
8090 | const Loop *LI = this->LI[I->getParent()]; |
8091 | if (LI && LI->getParentLoop() == L) // Looking for loop exit value. |
8092 | if (PHINode *PN = dyn_cast<PHINode>(I)) |
8093 | if (PN->getParent() == LI->getHeader()) { |
8094 | // Okay, there is no closed form solution for the PHI node. Check |
8095 | // to see if the loop that contains it has a known backedge-taken |
8096 | // count. If so, we may be able to force computation of the exit |
8097 | // value. |
8098 | const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI); |
8099 | if (const SCEVConstant *BTCC = |
8100 | dyn_cast<SCEVConstant>(BackedgeTakenCount)) { |
8101 | |
8102 | // This trivial case can show up in some degenerate cases where |
8103 | // the incoming IR has not yet been fully simplified. |
8104 | if (BTCC->getValue()->isZero()) { |
8105 | Value *InitValue = nullptr; |
8106 | bool MultipleInitValues = false; |
8107 | for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) { |
8108 | if (!LI->contains(PN->getIncomingBlock(i))) { |
8109 | if (!InitValue) |
8110 | InitValue = PN->getIncomingValue(i); |
8111 | else if (InitValue != PN->getIncomingValue(i)) { |
8112 | MultipleInitValues = true; |
Value stored to 'MultipleInitValues' is never read | |
8113 | break; |
8114 | } |
8115 | } |
8116 | if (!MultipleInitValues && InitValue) |
8117 | return getSCEV(InitValue); |
8118 | } |
8119 | } |
8120 | // Okay, we know how many times the containing loop executes. If |
8121 | // this is a constant evolving PHI node, get the final value at |
8122 | // the specified iteration number. |
8123 | Constant *RV = |
8124 | getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI); |
8125 | if (RV) return getSCEV(RV); |
8126 | } |
8127 | } |
8128 | |
8129 | // Okay, this is an expression that we cannot symbolically evaluate |
8130 | // into a SCEV. Check to see if it's possible to symbolically evaluate |
8131 | // the arguments into constants, and if so, try to constant propagate the |
8132 | // result. This is particularly useful for computing loop exit values. |
8133 | if (CanConstantFold(I)) { |
8134 | SmallVector<Constant *, 4> Operands; |
8135 | bool MadeImprovement = false; |
8136 | for (Value *Op : I->operands()) { |
8137 | if (Constant *C = dyn_cast<Constant>(Op)) { |
8138 | Operands.push_back(C); |
8139 | continue; |
8140 | } |
8141 | |
8142 | // If any of the operands is non-constant and if they are |
8143 | // non-integer and non-pointer, don't even try to analyze them |
8144 | // with scev techniques. |
8145 | if (!isSCEVable(Op->getType())) |
8146 | return V; |
8147 | |
8148 | const SCEV *OrigV = getSCEV(Op); |
8149 | const SCEV *OpV = getSCEVAtScope(OrigV, L); |
8150 | MadeImprovement |= OrigV != OpV; |
8151 | |
8152 | Constant *C = BuildConstantFromSCEV(OpV); |
8153 | if (!C) return V; |
8154 | if (C->getType() != Op->getType()) |
8155 | C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false, |
8156 | Op->getType(), |
8157 | false), |
8158 | C, Op->getType()); |
8159 | Operands.push_back(C); |
8160 | } |
8161 | |
8162 | // Check to see if getSCEVAtScope actually made an improvement. |
8163 | if (MadeImprovement) { |
8164 | Constant *C = nullptr; |
8165 | const DataLayout &DL = getDataLayout(); |
8166 | if (const CmpInst *CI = dyn_cast<CmpInst>(I)) |
8167 | C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0], |
8168 | Operands[1], DL, &TLI); |
8169 | else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) { |
8170 | if (!LI->isVolatile()) |
8171 | C = ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL); |
8172 | } else |
8173 | C = ConstantFoldInstOperands(I, Operands, DL, &TLI); |
8174 | if (!C) return V; |
8175 | return getSCEV(C); |
8176 | } |
8177 | } |
8178 | } |
8179 | |
8180 | // This is some other type of SCEVUnknown, just return it. |
8181 | return V; |
8182 | } |
8183 | |
8184 | if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) { |
8185 | // Avoid performing the look-up in the common case where the specified |
8186 | // expression has no loop-variant portions. |
8187 | for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) { |
8188 | const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L); |
8189 | if (OpAtScope != Comm->getOperand(i)) { |
8190 | // Okay, at least one of these operands is loop variant but might be |
8191 | // foldable. Build a new instance of the folded commutative expression. |
8192 | SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(), |
8193 | Comm->op_begin()+i); |
8194 | NewOps.push_back(OpAtScope); |
8195 | |
8196 | for (++i; i != e; ++i) { |
8197 | OpAtScope = getSCEVAtScope(Comm->getOperand(i), L); |
8198 | NewOps.push_back(OpAtScope); |
8199 | } |
8200 | if (isa<SCEVAddExpr>(Comm)) |
8201 | return getAddExpr(NewOps); |
8202 | if (isa<SCEVMulExpr>(Comm)) |
8203 | return getMulExpr(NewOps); |
8204 | if (isa<SCEVSMaxExpr>(Comm)) |
8205 | return getSMaxExpr(NewOps); |
8206 | if (isa<SCEVUMaxExpr>(Comm)) |
8207 | return getUMaxExpr(NewOps); |
8208 | llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8208); |
8209 | } |
8210 | } |
8211 | // If we got here, all operands are loop invariant. |
8212 | return Comm; |
8213 | } |
8214 | |
8215 | if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) { |
8216 | const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L); |
8217 | const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L); |
8218 | if (LHS == Div->getLHS() && RHS == Div->getRHS()) |
8219 | return Div; // must be loop invariant |
8220 | return getUDivExpr(LHS, RHS); |
8221 | } |
8222 | |
8223 | // If this is a loop recurrence for a loop that does not contain L, then we |
8224 | // are dealing with the final value computed by the loop. |
8225 | if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) { |
8226 | // First, attempt to evaluate each operand. |
8227 | // Avoid performing the look-up in the common case where the specified |
8228 | // expression has no loop-variant portions. |
8229 | for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) { |
8230 | const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L); |
8231 | if (OpAtScope == AddRec->getOperand(i)) |
8232 | continue; |
8233 | |
8234 | // Okay, at least one of these operands is loop variant but might be |
8235 | // foldable. Build a new instance of the folded commutative expression. |
8236 | SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(), |
8237 | AddRec->op_begin()+i); |
8238 | NewOps.push_back(OpAtScope); |
8239 | for (++i; i != e; ++i) |
8240 | NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L)); |
8241 | |
8242 | const SCEV *FoldedRec = |
8243 | getAddRecExpr(NewOps, AddRec->getLoop(), |
8244 | AddRec->getNoWrapFlags(SCEV::FlagNW)); |
8245 | AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec); |
8246 | // The addrec may be folded to a nonrecurrence, for example, if the |
8247 | // induction variable is multiplied by zero after constant folding. Go |
8248 | // ahead and return the folded value. |
8249 | if (!AddRec) |
8250 | return FoldedRec; |
8251 | break; |
8252 | } |
8253 | |
8254 | // If the scope is outside the addrec's loop, evaluate it by using the |
8255 | // loop exit value of the addrec. |
8256 | if (!AddRec->getLoop()->contains(L)) { |
8257 | // To evaluate this recurrence, we need to know how many times the AddRec |
8258 | // loop iterates. Compute this now. |
8259 | const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop()); |
8260 | if (BackedgeTakenCount == getCouldNotCompute()) return AddRec; |
8261 | |
8262 | // Then, evaluate the AddRec. |
8263 | return AddRec->evaluateAtIteration(BackedgeTakenCount, *this); |
8264 | } |
8265 | |
8266 | return AddRec; |
8267 | } |
8268 | |
8269 | if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) { |
8270 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); |
8271 | if (Op == Cast->getOperand()) |
8272 | return Cast; // must be loop invariant |
8273 | return getZeroExtendExpr(Op, Cast->getType()); |
8274 | } |
8275 | |
8276 | if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) { |
8277 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); |
8278 | if (Op == Cast->getOperand()) |
8279 | return Cast; // must be loop invariant |
8280 | return getSignExtendExpr(Op, Cast->getType()); |
8281 | } |
8282 | |
8283 | if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) { |
8284 | const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L); |
8285 | if (Op == Cast->getOperand()) |
8286 | return Cast; // must be loop invariant |
8287 | return getTruncateExpr(Op, Cast->getType()); |
8288 | } |
8289 | |
8290 | llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8290); |
8291 | } |
8292 | |
8293 | const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) { |
8294 | return getSCEVAtScope(getSCEV(V), L); |
8295 | } |
8296 | |
8297 | const SCEV *ScalarEvolution::stripInjectiveFunctions(const SCEV *S) const { |
8298 | if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) |
8299 | return stripInjectiveFunctions(ZExt->getOperand()); |
8300 | if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) |
8301 | return stripInjectiveFunctions(SExt->getOperand()); |
8302 | return S; |
8303 | } |
8304 | |
8305 | /// Finds the minimum unsigned root of the following equation: |
8306 | /// |
8307 | /// A * X = B (mod N) |
8308 | /// |
8309 | /// where N = 2^BW and BW is the common bit width of A and B. The signedness of |
8310 | /// A and B isn't important. |
8311 | /// |
8312 | /// If the equation does not have a solution, SCEVCouldNotCompute is returned. |
8313 | static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const SCEV *B, |
8314 | ScalarEvolution &SE) { |
8315 | uint32_t BW = A.getBitWidth(); |
8316 | assert(BW == SE.getTypeSizeInBits(B->getType()))((BW == SE.getTypeSizeInBits(B->getType())) ? static_cast< void> (0) : __assert_fail ("BW == SE.getTypeSizeInBits(B->getType())" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8316, __PRETTY_FUNCTION__)); |
8317 | assert(A != 0 && "A must be non-zero.")((A != 0 && "A must be non-zero.") ? static_cast<void > (0) : __assert_fail ("A != 0 && \"A must be non-zero.\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8317, __PRETTY_FUNCTION__)); |
8318 | |
8319 | // 1. D = gcd(A, N) |
8320 | // |
8321 | // The gcd of A and N may have only one prime factor: 2. The number of |
8322 | // trailing zeros in A is its multiplicity |
8323 | uint32_t Mult2 = A.countTrailingZeros(); |
8324 | // D = 2^Mult2 |
8325 | |
8326 | // 2. Check if B is divisible by D. |
8327 | // |
8328 | // B is divisible by D if and only if the multiplicity of prime factor 2 for B |
8329 | // is not less than multiplicity of this prime factor for D. |
8330 | if (SE.GetMinTrailingZeros(B) < Mult2) |
8331 | return SE.getCouldNotCompute(); |
8332 | |
8333 | // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic |
8334 | // modulo (N / D). |
8335 | // |
8336 | // If D == 1, (N / D) == N == 2^BW, so we need one extra bit to represent |
8337 | // (N / D) in general. The inverse itself always fits into BW bits, though, |
8338 | // so we immediately truncate it. |
8339 | APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D |
8340 | APInt Mod(BW + 1, 0); |
8341 | Mod.setBit(BW - Mult2); // Mod = N / D |
8342 | APInt I = AD.multiplicativeInverse(Mod).trunc(BW); |
8343 | |
8344 | // 4. Compute the minimum unsigned root of the equation: |
8345 | // I * (B / D) mod (N / D) |
8346 | // To simplify the computation, we factor out the divide by D: |
8347 | // (I * B mod N) / D |
8348 | const SCEV *D = SE.getConstant(APInt::getOneBitSet(BW, Mult2)); |
8349 | return SE.getUDivExactExpr(SE.getMulExpr(B, SE.getConstant(I)), D); |
8350 | } |
8351 | |
8352 | /// For a given quadratic addrec, generate coefficients of the corresponding |
8353 | /// quadratic equation, multiplied by a common value to ensure that they are |
8354 | /// integers. |
8355 | /// The returned value is a tuple { A, B, C, M, BitWidth }, where |
8356 | /// Ax^2 + Bx + C is the quadratic function, M is the value that A, B and C |
8357 | /// were multiplied by, and BitWidth is the bit width of the original addrec |
8358 | /// coefficients. |
8359 | /// This function returns None if the addrec coefficients are not compile- |
8360 | /// time constants. |
8361 | static Optional<std::tuple<APInt, APInt, APInt, APInt, unsigned>> |
8362 | GetQuadraticEquation(const SCEVAddRecExpr *AddRec) { |
8363 | assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!")((AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getNumOperands() == 3 && \"This is not a quadratic chrec!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8363, __PRETTY_FUNCTION__)); |
8364 | const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0)); |
8365 | const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1)); |
8366 | const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2)); |
8367 | LLVM_DEBUG(dbgs() << __func__ << ": analyzing quadratic addrec: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: " << *AddRec << '\n'; } } while (false) |
8368 | << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": analyzing quadratic addrec: " << *AddRec << '\n'; } } while (false); |
8369 | |
8370 | // We currently can only solve this if the coefficients are constants. |
8371 | if (!LC || !MC || !NC) { |
8372 | LLVM_DEBUG(dbgs() << __func__ << ": coefficients are not constant\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": coefficients are not constant\n" ; } } while (false); |
8373 | return None; |
8374 | } |
8375 | |
8376 | APInt L = LC->getAPInt(); |
8377 | APInt M = MC->getAPInt(); |
8378 | APInt N = NC->getAPInt(); |
8379 | assert(!N.isNullValue() && "This is not a quadratic addrec")((!N.isNullValue() && "This is not a quadratic addrec" ) ? static_cast<void> (0) : __assert_fail ("!N.isNullValue() && \"This is not a quadratic addrec\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8379, __PRETTY_FUNCTION__)); |
8380 | |
8381 | unsigned BitWidth = LC->getAPInt().getBitWidth(); |
8382 | unsigned NewWidth = BitWidth + 1; |
8383 | LLVM_DEBUG(dbgs() << __func__ << ": addrec coeff bw: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: " << BitWidth << '\n'; } } while (false) |
8384 | << BitWidth << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": addrec coeff bw: " << BitWidth << '\n'; } } while (false); |
8385 | // The sign-extension (as opposed to a zero-extension) here matches the |
8386 | // extension used in SolveQuadraticEquationWrap (with the same motivation). |
8387 | N = N.sext(NewWidth); |
8388 | M = M.sext(NewWidth); |
8389 | L = L.sext(NewWidth); |
8390 | |
8391 | // The increments are M, M+N, M+2N, ..., so the accumulated values are |
8392 | // L+M, (L+M)+(M+N), (L+M)+(M+N)+(M+2N), ..., that is, |
8393 | // L+M, L+2M+N, L+3M+3N, ... |
8394 | // After n iterations the accumulated value Acc is L + nM + n(n-1)/2 N. |
8395 | // |
8396 | // The equation Acc = 0 is then |
8397 | // L + nM + n(n-1)/2 N = 0, or 2L + 2M n + n(n-1) N = 0. |
8398 | // In a quadratic form it becomes: |
8399 | // N n^2 + (2M-N) n + 2L = 0. |
8400 | |
8401 | APInt A = N; |
8402 | APInt B = 2 * M - A; |
8403 | APInt C = 2 * L; |
8404 | APInt T = APInt(NewWidth, 2); |
8405 | LLVM_DEBUG(dbgs() << __func__ << ": equation " << A << "x^2 + " << Bdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": equation " << A << "x^2 + " << B << "x + " << C << ", coeff bw: " << NewWidth << ", multiplied by " << T << '\n'; } } while (false) |
8406 | << "x + " << C << ", coeff bw: " << NewWidthdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": equation " << A << "x^2 + " << B << "x + " << C << ", coeff bw: " << NewWidth << ", multiplied by " << T << '\n'; } } while (false) |
8407 | << ", multiplied by " << T << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": equation " << A << "x^2 + " << B << "x + " << C << ", coeff bw: " << NewWidth << ", multiplied by " << T << '\n'; } } while (false); |
8408 | return std::make_tuple(A, B, C, T, BitWidth); |
8409 | } |
8410 | |
8411 | /// Helper function to compare optional APInts: |
8412 | /// (a) if X and Y both exist, return min(X, Y), |
8413 | /// (b) if neither X nor Y exist, return None, |
8414 | /// (c) if exactly one of X and Y exists, return that value. |
8415 | static Optional<APInt> MinOptional(Optional<APInt> X, Optional<APInt> Y) { |
8416 | if (X.hasValue() && Y.hasValue()) { |
8417 | unsigned W = std::max(X->getBitWidth(), Y->getBitWidth()); |
8418 | APInt XW = X->sextOrSelf(W); |
8419 | APInt YW = Y->sextOrSelf(W); |
8420 | return XW.slt(YW) ? *X : *Y; |
8421 | } |
8422 | if (!X.hasValue() && !Y.hasValue()) |
8423 | return None; |
8424 | return X.hasValue() ? *X : *Y; |
8425 | } |
8426 | |
8427 | /// Helper function to truncate an optional APInt to a given BitWidth. |
8428 | /// When solving addrec-related equations, it is preferable to return a value |
8429 | /// that has the same bit width as the original addrec's coefficients. If the |
8430 | /// solution fits in the original bit width, truncate it (except for i1). |
8431 | /// Returning a value of a different bit width may inhibit some optimizations. |
8432 | /// |
8433 | /// In general, a solution to a quadratic equation generated from an addrec |
8434 | /// may require BW+1 bits, where BW is the bit width of the addrec's |
8435 | /// coefficients. The reason is that the coefficients of the quadratic |
8436 | /// equation are BW+1 bits wide (to avoid truncation when converting from |
8437 | /// the addrec to the equation). |
8438 | static Optional<APInt> TruncIfPossible(Optional<APInt> X, unsigned BitWidth) { |
8439 | if (!X.hasValue()) |
8440 | return None; |
8441 | unsigned W = X->getBitWidth(); |
8442 | if (BitWidth > 1 && BitWidth < W && X->isIntN(BitWidth)) |
8443 | return X->trunc(BitWidth); |
8444 | return X; |
8445 | } |
8446 | |
8447 | /// Let c(n) be the value of the quadratic chrec {L,+,M,+,N} after n |
8448 | /// iterations. The values L, M, N are assumed to be signed, and they |
8449 | /// should all have the same bit widths. |
8450 | /// Find the least n >= 0 such that c(n) = 0 in the arithmetic modulo 2^BW, |
8451 | /// where BW is the bit width of the addrec's coefficients. |
8452 | /// If the calculated value is a BW-bit integer (for BW > 1), it will be |
8453 | /// returned as such, otherwise the bit width of the returned value may |
8454 | /// be greater than BW. |
8455 | /// |
8456 | /// This function returns None if |
8457 | /// (a) the addrec coefficients are not constant, or |
8458 | /// (b) SolveQuadraticEquationWrap was unable to find a solution. For cases |
8459 | /// like x^2 = 5, no integer solutions exist, in other cases an integer |
8460 | /// solution may exist, but SolveQuadraticEquationWrap may fail to find it. |
8461 | static Optional<APInt> |
8462 | SolveQuadraticAddRecExact(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) { |
8463 | APInt A, B, C, M; |
8464 | unsigned BitWidth; |
8465 | auto T = GetQuadraticEquation(AddRec); |
8466 | if (!T.hasValue()) |
8467 | return None; |
8468 | |
8469 | std::tie(A, B, C, M, BitWidth) = *T; |
8470 | LLVM_DEBUG(dbgs() << __func__ << ": solving for unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": solving for unsigned overflow\n" ; } } while (false); |
8471 | Optional<APInt> X = APIntOps::SolveQuadraticEquationWrap(A, B, C, BitWidth+1); |
8472 | if (!X.hasValue()) |
8473 | return None; |
8474 | |
8475 | ConstantInt *CX = ConstantInt::get(SE.getContext(), *X); |
8476 | ConstantInt *V = EvaluateConstantChrecAtConstant(AddRec, CX, SE); |
8477 | if (!V->isZero()) |
8478 | return None; |
8479 | |
8480 | return TruncIfPossible(X, BitWidth); |
8481 | } |
8482 | |
8483 | /// Let c(n) be the value of the quadratic chrec {0,+,M,+,N} after n |
8484 | /// iterations. The values M, N are assumed to be signed, and they |
8485 | /// should all have the same bit widths. |
8486 | /// Find the least n such that c(n) does not belong to the given range, |
8487 | /// while c(n-1) does. |
8488 | /// |
8489 | /// This function returns None if |
8490 | /// (a) the addrec coefficients are not constant, or |
8491 | /// (b) SolveQuadraticEquationWrap was unable to find a solution for the |
8492 | /// bounds of the range. |
8493 | static Optional<APInt> |
8494 | SolveQuadraticAddRecRange(const SCEVAddRecExpr *AddRec, |
8495 | const ConstantRange &Range, ScalarEvolution &SE) { |
8496 | assert(AddRec->getOperand(0)->isZero() &&((AddRec->getOperand(0)->isZero() && "Starting value of addrec should be 0" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8497, __PRETTY_FUNCTION__)) |
8497 | "Starting value of addrec should be 0")((AddRec->getOperand(0)->isZero() && "Starting value of addrec should be 0" ) ? static_cast<void> (0) : __assert_fail ("AddRec->getOperand(0)->isZero() && \"Starting value of addrec should be 0\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8497, __PRETTY_FUNCTION__)); |
8498 | LLVM_DEBUG(dbgs() << __func__ << ": solving boundary crossing for range "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": solving boundary crossing for range " << Range << ", addrec " << *AddRec << '\n'; } } while (false) |
8499 | << Range << ", addrec " << *AddRec << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << __func__ << ": solving boundary crossing for range " << Range << ", addrec " << *AddRec << '\n'; } } while (false); |
8500 | // This case is handled in getNumIterationsInRange. Here we can assume that |
8501 | // we start in the range. |
8502 | assert(Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) &&((Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType ()), 0)) && "Addrec's initial value should be in range" ) ? static_cast<void> (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8503, __PRETTY_FUNCTION__)) |
8503 | "Addrec's initial value should be in range")((Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType ()), 0)) && "Addrec's initial value should be in range" ) ? static_cast<void> (0) : __assert_fail ("Range.contains(APInt(SE.getTypeSizeInBits(AddRec->getType()), 0)) && \"Addrec's initial value should be in range\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8503, __PRETTY_FUNCTION__)); |
8504 | |
8505 | APInt A, B, C, M; |
8506 | unsigned BitWidth; |
8507 | auto T = GetQuadraticEquation(AddRec); |
8508 | if (!T.hasValue()) |
8509 | return None; |
8510 | |
8511 | // Be careful about the return value: there can be two reasons for not |
8512 | // returning an actual number. First, if no solutions to the equations |
8513 | // were found, and second, if the solutions don't leave the given range. |
8514 | // The first case means that the actual solution is "unknown", the second |
8515 | // means that it's known, but not valid. If the solution is unknown, we |
8516 | // cannot make any conclusions. |
8517 | // Return a pair: the optional solution and a flag indicating if the |
8518 | // solution was found. |
8519 | auto SolveForBoundary = [&](APInt Bound) -> std::pair<Optional<APInt>,bool> { |
8520 | // Solve for signed overflow and unsigned overflow, pick the lower |
8521 | // solution. |
8522 | LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: checking boundary "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: checking boundary " << Bound << " (before multiplying by " << M << ")\n"; } } while (false) |
8523 | << Bound << " (before multiplying by " << M << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: checking boundary " << Bound << " (before multiplying by " << M << ")\n"; } } while (false); |
8524 | Bound *= M; // The quadratic equation multiplier. |
8525 | |
8526 | Optional<APInt> SO = None; |
8527 | if (BitWidth > 1) { |
8528 | LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "signed overflow\n"; } } while (false) |
8529 | "signed overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "signed overflow\n"; } } while (false); |
8530 | SO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, BitWidth); |
8531 | } |
8532 | LLVM_DEBUG(dbgs() << "SolveQuadraticAddRecRange: solving for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "unsigned overflow\n"; } } while (false) |
8533 | "unsigned overflow\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { dbgs() << "SolveQuadraticAddRecRange: solving for " "unsigned overflow\n"; } } while (false); |
8534 | Optional<APInt> UO = APIntOps::SolveQuadraticEquationWrap(A, B, -Bound, |
8535 | BitWidth+1); |
8536 | |
8537 | auto LeavesRange = [&] (const APInt &X) { |
8538 | ConstantInt *C0 = ConstantInt::get(SE.getContext(), X); |
8539 | ConstantInt *V0 = EvaluateConstantChrecAtConstant(AddRec, C0, SE); |
8540 | if (Range.contains(V0->getValue())) |
8541 | return false; |
8542 | // X should be at least 1, so X-1 is non-negative. |
8543 | ConstantInt *C1 = ConstantInt::get(SE.getContext(), X-1); |
8544 | ConstantInt *V1 = EvaluateConstantChrecAtConstant(AddRec, C1, SE); |
8545 | if (Range.contains(V1->getValue())) |
8546 | return true; |
8547 | return false; |
8548 | }; |
8549 | |
8550 | // If SolveQuadraticEquationWrap returns None, it means that there can |
8551 | // be a solution, but the function failed to find it. We cannot treat it |
8552 | // as "no solution". |
8553 | if (!SO.hasValue() || !UO.hasValue()) |
8554 | return { None, false }; |
8555 | |
8556 | // Check the smaller value first to see if it leaves the range. |
8557 | // At this point, both SO and UO must have values. |
8558 | Optional<APInt> Min = MinOptional(SO, UO); |
8559 | if (LeavesRange(*Min)) |
8560 | return { Min, true }; |
8561 | Optional<APInt> Max = Min == SO ? UO : SO; |
8562 | if (LeavesRange(*Max)) |
8563 | return { Max, true }; |
8564 | |
8565 | // Solutions were found, but were eliminated, hence the "true". |
8566 | return { None, true }; |
8567 | }; |
8568 | |
8569 | std::tie(A, B, C, M, BitWidth) = *T; |
8570 | // Lower bound is inclusive, subtract 1 to represent the exiting value. |
8571 | APInt Lower = Range.getLower().sextOrSelf(A.getBitWidth()) - 1; |
8572 | APInt Upper = Range.getUpper().sextOrSelf(A.getBitWidth()); |
8573 | auto SL = SolveForBoundary(Lower); |
8574 | auto SU = SolveForBoundary(Upper); |
8575 | // If any of the solutions was unknown, no meaninigful conclusions can |
8576 | // be made. |
8577 | if (!SL.second || !SU.second) |
8578 | return None; |
8579 | |
8580 | // Claim: The correct solution is not some value between Min and Max. |
8581 | // |
8582 | // Justification: Assuming that Min and Max are different values, one of |
8583 | // them is when the first signed overflow happens, the other is when the |
8584 | // first unsigned overflow happens. Crossing the range boundary is only |
8585 | // possible via an overflow (treating 0 as a special case of it, modeling |
8586 | // an overflow as crossing k*2^W for some k). |
8587 | // |
8588 | // The interesting case here is when Min was eliminated as an invalid |
8589 | // solution, but Max was not. The argument is that if there was another |
8590 | // overflow between Min and Max, it would also have been eliminated if |
8591 | // it was considered. |
8592 | // |
8593 | // For a given boundary, it is possible to have two overflows of the same |
8594 | // type (signed/unsigned) without having the other type in between: this |
8595 | // can happen when the vertex of the parabola is between the iterations |
8596 | // corresponding to the overflows. This is only possible when the two |
8597 | // overflows cross k*2^W for the same k. In such case, if the second one |
8598 | // left the range (and was the first one to do so), the first overflow |
8599 | // would have to enter the range, which would mean that either we had left |
8600 | // the range before or that we started outside of it. Both of these cases |
8601 | // are contradictions. |
8602 | // |
8603 | // Claim: In the case where SolveForBoundary returns None, the correct |
8604 | // solution is not some value between the Max for this boundary and the |
8605 | // Min of the other boundary. |
8606 | // |
8607 | // Justification: Assume that we had such Max_A and Min_B corresponding |
8608 | // to range boundaries A and B and such that Max_A < Min_B. If there was |
8609 | // a solution between Max_A and Min_B, it would have to be caused by an |
8610 | // overflow corresponding to either A or B. It cannot correspond to B, |
8611 | // since Min_B is the first occurrence of such an overflow. If it |
8612 | // corresponded to A, it would have to be either a signed or an unsigned |
8613 | // overflow that is larger than both eliminated overflows for A. But |
8614 | // between the eliminated overflows and this overflow, the values would |
8615 | // cover the entire value space, thus crossing the other boundary, which |
8616 | // is a contradiction. |
8617 | |
8618 | return TruncIfPossible(MinOptional(SL.first, SU.first), BitWidth); |
8619 | } |
8620 | |
8621 | ScalarEvolution::ExitLimit |
8622 | ScalarEvolution::howFarToZero(const SCEV *V, const Loop *L, bool ControlsExit, |
8623 | bool AllowPredicates) { |
8624 | |
8625 | // This is only used for loops with a "x != y" exit test. The exit condition |
8626 | // is now expressed as a single expression, V = x-y. So the exit test is |
8627 | // effectively V != 0. We know and take advantage of the fact that this |
8628 | // expression only being used in a comparison by zero context. |
8629 | |
8630 | SmallPtrSet<const SCEVPredicate *, 4> Predicates; |
8631 | // If the value is a constant |
8632 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { |
8633 | // If the value is already zero, the branch will execute zero times. |
8634 | if (C->getValue()->isZero()) return C; |
8635 | return getCouldNotCompute(); // Otherwise it will loop infinitely. |
8636 | } |
8637 | |
8638 | const SCEVAddRecExpr *AddRec = |
8639 | dyn_cast<SCEVAddRecExpr>(stripInjectiveFunctions(V)); |
8640 | |
8641 | if (!AddRec && AllowPredicates) |
8642 | // Try to make this an AddRec using runtime tests, in the first X |
8643 | // iterations of this loop, where X is the SCEV expression found by the |
8644 | // algorithm below. |
8645 | AddRec = convertSCEVToAddRecWithPredicates(V, L, Predicates); |
8646 | |
8647 | if (!AddRec || AddRec->getLoop() != L) |
8648 | return getCouldNotCompute(); |
8649 | |
8650 | // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of |
8651 | // the quadratic equation to solve it. |
8652 | if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) { |
8653 | // We can only use this value if the chrec ends up with an exact zero |
8654 | // value at this index. When solving for "X*X != 5", for example, we |
8655 | // should not accept a root of 2. |
8656 | if (auto S = SolveQuadraticAddRecExact(AddRec, *this)) { |
8657 | const auto *R = cast<SCEVConstant>(getConstant(S.getValue())); |
8658 | return ExitLimit(R, R, false, Predicates); |
8659 | } |
8660 | return getCouldNotCompute(); |
8661 | } |
8662 | |
8663 | // Otherwise we can only handle this if it is affine. |
8664 | if (!AddRec->isAffine()) |
8665 | return getCouldNotCompute(); |
8666 | |
8667 | // If this is an affine expression, the execution count of this branch is |
8668 | // the minimum unsigned root of the following equation: |
8669 | // |
8670 | // Start + Step*N = 0 (mod 2^BW) |
8671 | // |
8672 | // equivalent to: |
8673 | // |
8674 | // Step*N = -Start (mod 2^BW) |
8675 | // |
8676 | // where BW is the common bit width of Start and Step. |
8677 | |
8678 | // Get the initial value for the loop. |
8679 | const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop()); |
8680 | const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop()); |
8681 | |
8682 | // For now we handle only constant steps. |
8683 | // |
8684 | // TODO: Handle a nonconstant Step given AddRec<NUW>. If the |
8685 | // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap |
8686 | // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step. |
8687 | // We have not yet seen any such cases. |
8688 | const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step); |
8689 | if (!StepC || StepC->getValue()->isZero()) |
8690 | return getCouldNotCompute(); |
8691 | |
8692 | // For positive steps (counting up until unsigned overflow): |
8693 | // N = -Start/Step (as unsigned) |
8694 | // For negative steps (counting down to zero): |
8695 | // N = Start/-Step |
8696 | // First compute the unsigned distance from zero in the direction of Step. |
8697 | bool CountDown = StepC->getAPInt().isNegative(); |
8698 | const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start); |
8699 | |
8700 | // Handle unitary steps, which cannot wraparound. |
8701 | // 1*N = -Start; -1*N = Start (mod 2^BW), so: |
8702 | // N = Distance (as unsigned) |
8703 | if (StepC->getValue()->isOne() || StepC->getValue()->isMinusOne()) { |
8704 | APInt MaxBECount = getUnsignedRangeMax(Distance); |
8705 | |
8706 | // When a loop like "for (int i = 0; i != n; ++i) { /* body */ }" is rotated, |
8707 | // we end up with a loop whose backedge-taken count is n - 1. Detect this |
8708 | // case, and see if we can improve the bound. |
8709 | // |
8710 | // Explicitly handling this here is necessary because getUnsignedRange |
8711 | // isn't context-sensitive; it doesn't know that we only care about the |
8712 | // range inside the loop. |
8713 | const SCEV *Zero = getZero(Distance->getType()); |
8714 | const SCEV *One = getOne(Distance->getType()); |
8715 | const SCEV *DistancePlusOne = getAddExpr(Distance, One); |
8716 | if (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, DistancePlusOne, Zero)) { |
8717 | // If Distance + 1 doesn't overflow, we can compute the maximum distance |
8718 | // as "unsigned_max(Distance + 1) - 1". |
8719 | ConstantRange CR = getUnsignedRange(DistancePlusOne); |
8720 | MaxBECount = APIntOps::umin(MaxBECount, CR.getUnsignedMax() - 1); |
8721 | } |
8722 | return ExitLimit(Distance, getConstant(MaxBECount), false, Predicates); |
8723 | } |
8724 | |
8725 | // If the condition controls loop exit (the loop exits only if the expression |
8726 | // is true) and the addition is no-wrap we can use unsigned divide to |
8727 | // compute the backedge count. In this case, the step may not divide the |
8728 | // distance, but we don't care because if the condition is "missed" the loop |
8729 | // will have undefined behavior due to wrapping. |
8730 | if (ControlsExit && AddRec->hasNoSelfWrap() && |
8731 | loopHasNoAbnormalExits(AddRec->getLoop())) { |
8732 | const SCEV *Exact = |
8733 | getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step); |
8734 | const SCEV *Max = |
8735 | Exact == getCouldNotCompute() |
8736 | ? Exact |
8737 | : getConstant(getUnsignedRangeMax(Exact)); |
8738 | return ExitLimit(Exact, Max, false, Predicates); |
8739 | } |
8740 | |
8741 | // Solve the general equation. |
8742 | const SCEV *E = SolveLinEquationWithOverflow(StepC->getAPInt(), |
8743 | getNegativeSCEV(Start), *this); |
8744 | const SCEV *M = E == getCouldNotCompute() |
8745 | ? E |
8746 | : getConstant(getUnsignedRangeMax(E)); |
8747 | return ExitLimit(E, M, false, Predicates); |
8748 | } |
8749 | |
8750 | ScalarEvolution::ExitLimit |
8751 | ScalarEvolution::howFarToNonZero(const SCEV *V, const Loop *L) { |
8752 | // Loops that look like: while (X == 0) are very strange indeed. We don't |
8753 | // handle them yet except for the trivial case. This could be expanded in the |
8754 | // future as needed. |
8755 | |
8756 | // If the value is a constant, check to see if it is known to be non-zero |
8757 | // already. If so, the backedge will execute zero times. |
8758 | if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) { |
8759 | if (!C->getValue()->isZero()) |
8760 | return getZero(C->getType()); |
8761 | return getCouldNotCompute(); // Otherwise it will loop infinitely. |
8762 | } |
8763 | |
8764 | // We could implement others, but I really doubt anyone writes loops like |
8765 | // this, and if they did, they would already be constant folded. |
8766 | return getCouldNotCompute(); |
8767 | } |
8768 | |
8769 | std::pair<BasicBlock *, BasicBlock *> |
8770 | ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) { |
8771 | // If the block has a unique predecessor, then there is no path from the |
8772 | // predecessor to the block that does not go through the direct edge |
8773 | // from the predecessor to the block. |
8774 | if (BasicBlock *Pred = BB->getSinglePredecessor()) |
8775 | return {Pred, BB}; |
8776 | |
8777 | // A loop's header is defined to be a block that dominates the loop. |
8778 | // If the header has a unique predecessor outside the loop, it must be |
8779 | // a block that has exactly one successor that can reach the loop. |
8780 | if (Loop *L = LI.getLoopFor(BB)) |
8781 | return {L->getLoopPredecessor(), L->getHeader()}; |
8782 | |
8783 | return {nullptr, nullptr}; |
8784 | } |
8785 | |
8786 | /// SCEV structural equivalence is usually sufficient for testing whether two |
8787 | /// expressions are equal, however for the purposes of looking for a condition |
8788 | /// guarding a loop, it can be useful to be a little more general, since a |
8789 | /// front-end may have replicated the controlling expression. |
8790 | static bool HasSameValue(const SCEV *A, const SCEV *B) { |
8791 | // Quick check to see if they are the same SCEV. |
8792 | if (A == B) return true; |
8793 | |
8794 | auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) { |
8795 | // Not all instructions that are "identical" compute the same value. For |
8796 | // instance, two distinct alloca instructions allocating the same type are |
8797 | // identical and do not read memory; but compute distinct values. |
8798 | return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A)); |
8799 | }; |
8800 | |
8801 | // Otherwise, if they're both SCEVUnknown, it's possible that they hold |
8802 | // two different instructions with the same value. Check for this case. |
8803 | if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A)) |
8804 | if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B)) |
8805 | if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue())) |
8806 | if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue())) |
8807 | if (ComputesEqualValues(AI, BI)) |
8808 | return true; |
8809 | |
8810 | // Otherwise assume they may have a different value. |
8811 | return false; |
8812 | } |
8813 | |
8814 | bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred, |
8815 | const SCEV *&LHS, const SCEV *&RHS, |
8816 | unsigned Depth) { |
8817 | bool Changed = false; |
8818 | // Simplifies ICMP to trivial true or false by turning it into '0 == 0' or |
8819 | // '0 != 0'. |
8820 | auto TrivialCase = [&](bool TriviallyTrue) { |
8821 | LHS = RHS = getConstant(ConstantInt::getFalse(getContext())); |
8822 | Pred = TriviallyTrue ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE; |
8823 | return true; |
8824 | }; |
8825 | // If we hit the max recursion limit bail out. |
8826 | if (Depth >= 3) |
8827 | return false; |
8828 | |
8829 | // Canonicalize a constant to the right side. |
8830 | if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) { |
8831 | // Check for both operands constant. |
8832 | if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) { |
8833 | if (ConstantExpr::getICmp(Pred, |
8834 | LHSC->getValue(), |
8835 | RHSC->getValue())->isNullValue()) |
8836 | return TrivialCase(false); |
8837 | else |
8838 | return TrivialCase(true); |
8839 | } |
8840 | // Otherwise swap the operands to put the constant on the right. |
8841 | std::swap(LHS, RHS); |
8842 | Pred = ICmpInst::getSwappedPredicate(Pred); |
8843 | Changed = true; |
8844 | } |
8845 | |
8846 | // If we're comparing an addrec with a value which is loop-invariant in the |
8847 | // addrec's loop, put the addrec on the left. Also make a dominance check, |
8848 | // as both operands could be addrecs loop-invariant in each other's loop. |
8849 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) { |
8850 | const Loop *L = AR->getLoop(); |
8851 | if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) { |
8852 | std::swap(LHS, RHS); |
8853 | Pred = ICmpInst::getSwappedPredicate(Pred); |
8854 | Changed = true; |
8855 | } |
8856 | } |
8857 | |
8858 | // If there's a constant operand, canonicalize comparisons with boundary |
8859 | // cases, and canonicalize *-or-equal comparisons to regular comparisons. |
8860 | if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) { |
8861 | const APInt &RA = RC->getAPInt(); |
8862 | |
8863 | bool SimplifiedByConstantRange = false; |
8864 | |
8865 | if (!ICmpInst::isEquality(Pred)) { |
8866 | ConstantRange ExactCR = ConstantRange::makeExactICmpRegion(Pred, RA); |
8867 | if (ExactCR.isFullSet()) |
8868 | return TrivialCase(true); |
8869 | else if (ExactCR.isEmptySet()) |
8870 | return TrivialCase(false); |
8871 | |
8872 | APInt NewRHS; |
8873 | CmpInst::Predicate NewPred; |
8874 | if (ExactCR.getEquivalentICmp(NewPred, NewRHS) && |
8875 | ICmpInst::isEquality(NewPred)) { |
8876 | // We were able to convert an inequality to an equality. |
8877 | Pred = NewPred; |
8878 | RHS = getConstant(NewRHS); |
8879 | Changed = SimplifiedByConstantRange = true; |
8880 | } |
8881 | } |
8882 | |
8883 | if (!SimplifiedByConstantRange) { |
8884 | switch (Pred) { |
8885 | default: |
8886 | break; |
8887 | case ICmpInst::ICMP_EQ: |
8888 | case ICmpInst::ICMP_NE: |
8889 | // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b. |
8890 | if (!RA) |
8891 | if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS)) |
8892 | if (const SCEVMulExpr *ME = |
8893 | dyn_cast<SCEVMulExpr>(AE->getOperand(0))) |
8894 | if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 && |
8895 | ME->getOperand(0)->isAllOnesValue()) { |
8896 | RHS = AE->getOperand(1); |
8897 | LHS = ME->getOperand(1); |
8898 | Changed = true; |
8899 | } |
8900 | break; |
8901 | |
8902 | |
8903 | // The "Should have been caught earlier!" messages refer to the fact |
8904 | // that the ExactCR.isFullSet() or ExactCR.isEmptySet() check above |
8905 | // should have fired on the corresponding cases, and canonicalized the |
8906 | // check to trivial case. |
8907 | |
8908 | case ICmpInst::ICMP_UGE: |
8909 | assert(!RA.isMinValue() && "Should have been caught earlier!")((!RA.isMinValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMinValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8909, __PRETTY_FUNCTION__)); |
8910 | Pred = ICmpInst::ICMP_UGT; |
8911 | RHS = getConstant(RA - 1); |
8912 | Changed = true; |
8913 | break; |
8914 | case ICmpInst::ICMP_ULE: |
8915 | assert(!RA.isMaxValue() && "Should have been caught earlier!")((!RA.isMaxValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMaxValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8915, __PRETTY_FUNCTION__)); |
8916 | Pred = ICmpInst::ICMP_ULT; |
8917 | RHS = getConstant(RA + 1); |
8918 | Changed = true; |
8919 | break; |
8920 | case ICmpInst::ICMP_SGE: |
8921 | assert(!RA.isMinSignedValue() && "Should have been caught earlier!")((!RA.isMinSignedValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMinSignedValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8921, __PRETTY_FUNCTION__)); |
8922 | Pred = ICmpInst::ICMP_SGT; |
8923 | RHS = getConstant(RA - 1); |
8924 | Changed = true; |
8925 | break; |
8926 | case ICmpInst::ICMP_SLE: |
8927 | assert(!RA.isMaxSignedValue() && "Should have been caught earlier!")((!RA.isMaxSignedValue() && "Should have been caught earlier!" ) ? static_cast<void> (0) : __assert_fail ("!RA.isMaxSignedValue() && \"Should have been caught earlier!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 8927, __PRETTY_FUNCTION__)); |
8928 | Pred = ICmpInst::ICMP_SLT; |
8929 | RHS = getConstant(RA + 1); |
8930 | Changed = true; |
8931 | break; |
8932 | } |
8933 | } |
8934 | } |
8935 | |
8936 | // Check for obvious equality. |
8937 | if (HasSameValue(LHS, RHS)) { |
8938 | if (ICmpInst::isTrueWhenEqual(Pred)) |
8939 | return TrivialCase(true); |
8940 | if (ICmpInst::isFalseWhenEqual(Pred)) |
8941 | return TrivialCase(false); |
8942 | } |
8943 | |
8944 | // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by |
8945 | // adding or subtracting 1 from one of the operands. |
8946 | switch (Pred) { |
8947 | case ICmpInst::ICMP_SLE: |
8948 | if (!getSignedRangeMax(RHS).isMaxSignedValue()) { |
8949 | RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS, |
8950 | SCEV::FlagNSW); |
8951 | Pred = ICmpInst::ICMP_SLT; |
8952 | Changed = true; |
8953 | } else if (!getSignedRangeMin(LHS).isMinSignedValue()) { |
8954 | LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS, |
8955 | SCEV::FlagNSW); |
8956 | Pred = ICmpInst::ICMP_SLT; |
8957 | Changed = true; |
8958 | } |
8959 | break; |
8960 | case ICmpInst::ICMP_SGE: |
8961 | if (!getSignedRangeMin(RHS).isMinSignedValue()) { |
8962 | RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS, |
8963 | SCEV::FlagNSW); |
8964 | Pred = ICmpInst::ICMP_SGT; |
8965 | Changed = true; |
8966 | } else if (!getSignedRangeMax(LHS).isMaxSignedValue()) { |
8967 | LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS, |
8968 | SCEV::FlagNSW); |
8969 | Pred = ICmpInst::ICMP_SGT; |
8970 | Changed = true; |
8971 | } |
8972 | break; |
8973 | case ICmpInst::ICMP_ULE: |
8974 | if (!getUnsignedRangeMax(RHS).isMaxValue()) { |
8975 | RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS, |
8976 | SCEV::FlagNUW); |
8977 | Pred = ICmpInst::ICMP_ULT; |
8978 | Changed = true; |
8979 | } else if (!getUnsignedRangeMin(LHS).isMinValue()) { |
8980 | LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS); |
8981 | Pred = ICmpInst::ICMP_ULT; |
8982 | Changed = true; |
8983 | } |
8984 | break; |
8985 | case ICmpInst::ICMP_UGE: |
8986 | if (!getUnsignedRangeMin(RHS).isMinValue()) { |
8987 | RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS); |
8988 | Pred = ICmpInst::ICMP_UGT; |
8989 | Changed = true; |
8990 | } else if (!getUnsignedRangeMax(LHS).isMaxValue()) { |
8991 | LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS, |
8992 | SCEV::FlagNUW); |
8993 | Pred = ICmpInst::ICMP_UGT; |
8994 | Changed = true; |
8995 | } |
8996 | break; |
8997 | default: |
8998 | break; |
8999 | } |
9000 | |
9001 | // TODO: More simplifications are possible here. |
9002 | |
9003 | // Recursively simplify until we either hit a recursion limit or nothing |
9004 | // changes. |
9005 | if (Changed) |
9006 | return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1); |
9007 | |
9008 | return Changed; |
9009 | } |
9010 | |
9011 | bool ScalarEvolution::isKnownNegative(const SCEV *S) { |
9012 | return getSignedRangeMax(S).isNegative(); |
9013 | } |
9014 | |
9015 | bool ScalarEvolution::isKnownPositive(const SCEV *S) { |
9016 | return getSignedRangeMin(S).isStrictlyPositive(); |
9017 | } |
9018 | |
9019 | bool ScalarEvolution::isKnownNonNegative(const SCEV *S) { |
9020 | return !getSignedRangeMin(S).isNegative(); |
9021 | } |
9022 | |
9023 | bool ScalarEvolution::isKnownNonPositive(const SCEV *S) { |
9024 | return !getSignedRangeMax(S).isStrictlyPositive(); |
9025 | } |
9026 | |
9027 | bool ScalarEvolution::isKnownNonZero(const SCEV *S) { |
9028 | return isKnownNegative(S) || isKnownPositive(S); |
9029 | } |
9030 | |
9031 | std::pair<const SCEV *, const SCEV *> |
9032 | ScalarEvolution::SplitIntoInitAndPostInc(const Loop *L, const SCEV *S) { |
9033 | // Compute SCEV on entry of loop L. |
9034 | const SCEV *Start = SCEVInitRewriter::rewrite(S, L, *this); |
9035 | if (Start == getCouldNotCompute()) |
9036 | return { Start, Start }; |
9037 | // Compute post increment SCEV for loop L. |
9038 | const SCEV *PostInc = SCEVPostIncRewriter::rewrite(S, L, *this); |
9039 | assert(PostInc != getCouldNotCompute() && "Unexpected could not compute")((PostInc != getCouldNotCompute() && "Unexpected could not compute" ) ? static_cast<void> (0) : __assert_fail ("PostInc != getCouldNotCompute() && \"Unexpected could not compute\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9039, __PRETTY_FUNCTION__)); |
9040 | return { Start, PostInc }; |
9041 | } |
9042 | |
9043 | bool ScalarEvolution::isKnownViaInduction(ICmpInst::Predicate Pred, |
9044 | const SCEV *LHS, const SCEV *RHS) { |
9045 | // First collect all loops. |
9046 | SmallPtrSet<const Loop *, 8> LoopsUsed; |
9047 | getUsedLoops(LHS, LoopsUsed); |
9048 | getUsedLoops(RHS, LoopsUsed); |
9049 | |
9050 | if (LoopsUsed.empty()) |
9051 | return false; |
9052 | |
9053 | // Domination relationship must be a linear order on collected loops. |
9054 | #ifndef NDEBUG |
9055 | for (auto *L1 : LoopsUsed) |
9056 | for (auto *L2 : LoopsUsed) |
9057 | assert((DT.dominates(L1->getHeader(), L2->getHeader()) ||(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT .dominates(L2->getHeader(), L1->getHeader())) && "Domination relationship is not a linear order") ? static_cast <void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9059, __PRETTY_FUNCTION__)) |
9058 | DT.dominates(L2->getHeader(), L1->getHeader())) &&(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT .dominates(L2->getHeader(), L1->getHeader())) && "Domination relationship is not a linear order") ? static_cast <void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9059, __PRETTY_FUNCTION__)) |
9059 | "Domination relationship is not a linear order")(((DT.dominates(L1->getHeader(), L2->getHeader()) || DT .dominates(L2->getHeader(), L1->getHeader())) && "Domination relationship is not a linear order") ? static_cast <void> (0) : __assert_fail ("(DT.dominates(L1->getHeader(), L2->getHeader()) || DT.dominates(L2->getHeader(), L1->getHeader())) && \"Domination relationship is not a linear order\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9059, __PRETTY_FUNCTION__)); |
9060 | #endif |
9061 | |
9062 | const Loop *MDL = |
9063 | *std::max_element(LoopsUsed.begin(), LoopsUsed.end(), |
9064 | [&](const Loop *L1, const Loop *L2) { |
9065 | return DT.properlyDominates(L1->getHeader(), L2->getHeader()); |
9066 | }); |
9067 | |
9068 | // Get init and post increment value for LHS. |
9069 | auto SplitLHS = SplitIntoInitAndPostInc(MDL, LHS); |
9070 | // if LHS contains unknown non-invariant SCEV then bail out. |
9071 | if (SplitLHS.first == getCouldNotCompute()) |
9072 | return false; |
9073 | assert (SplitLHS.second != getCouldNotCompute() && "Unexpected CNC")((SplitLHS.second != getCouldNotCompute() && "Unexpected CNC" ) ? static_cast<void> (0) : __assert_fail ("SplitLHS.second != getCouldNotCompute() && \"Unexpected CNC\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9073, __PRETTY_FUNCTION__)); |
9074 | // Get init and post increment value for RHS. |
9075 | auto SplitRHS = SplitIntoInitAndPostInc(MDL, RHS); |
9076 | // if RHS contains unknown non-invariant SCEV then bail out. |
9077 | if (SplitRHS.first == getCouldNotCompute()) |
9078 | return false; |
9079 | assert (SplitRHS.second != getCouldNotCompute() && "Unexpected CNC")((SplitRHS.second != getCouldNotCompute() && "Unexpected CNC" ) ? static_cast<void> (0) : __assert_fail ("SplitRHS.second != getCouldNotCompute() && \"Unexpected CNC\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9079, __PRETTY_FUNCTION__)); |
9080 | // It is possible that init SCEV contains an invariant load but it does |
9081 | // not dominate MDL and is not available at MDL loop entry, so we should |
9082 | // check it here. |
9083 | if (!isAvailableAtLoopEntry(SplitLHS.first, MDL) || |
9084 | !isAvailableAtLoopEntry(SplitRHS.first, MDL)) |
9085 | return false; |
9086 | |
9087 | return isLoopEntryGuardedByCond(MDL, Pred, SplitLHS.first, SplitRHS.first) && |
9088 | isLoopBackedgeGuardedByCond(MDL, Pred, SplitLHS.second, |
9089 | SplitRHS.second); |
9090 | } |
9091 | |
9092 | bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred, |
9093 | const SCEV *LHS, const SCEV *RHS) { |
9094 | // Canonicalize the inputs first. |
9095 | (void)SimplifyICmpOperands(Pred, LHS, RHS); |
9096 | |
9097 | if (isKnownViaInduction(Pred, LHS, RHS)) |
9098 | return true; |
9099 | |
9100 | if (isKnownPredicateViaSplitting(Pred, LHS, RHS)) |
9101 | return true; |
9102 | |
9103 | // Otherwise see what can be done with some simple reasoning. |
9104 | return isKnownViaNonRecursiveReasoning(Pred, LHS, RHS); |
9105 | } |
9106 | |
9107 | bool ScalarEvolution::isKnownOnEveryIteration(ICmpInst::Predicate Pred, |
9108 | const SCEVAddRecExpr *LHS, |
9109 | const SCEV *RHS) { |
9110 | const Loop *L = LHS->getLoop(); |
9111 | return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) && |
9112 | isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS); |
9113 | } |
9114 | |
9115 | bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS, |
9116 | ICmpInst::Predicate Pred, |
9117 | bool &Increasing) { |
9118 | bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing); |
9119 | |
9120 | #ifndef NDEBUG |
9121 | // Verify an invariant: inverting the predicate should turn a monotonically |
9122 | // increasing change to a monotonically decreasing one, and vice versa. |
9123 | bool IncreasingSwapped; |
9124 | bool ResultSwapped = isMonotonicPredicateImpl( |
9125 | LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped); |
9126 | |
9127 | assert(Result == ResultSwapped && "should be able to analyze both!")((Result == ResultSwapped && "should be able to analyze both!" ) ? static_cast<void> (0) : __assert_fail ("Result == ResultSwapped && \"should be able to analyze both!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9127, __PRETTY_FUNCTION__)); |
9128 | if (ResultSwapped) |
9129 | assert(Increasing == !IncreasingSwapped &&((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate" ) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9130, __PRETTY_FUNCTION__)) |
9130 | "monotonicity should flip as we flip the predicate")((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate" ) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9130, __PRETTY_FUNCTION__)); |
9131 | #endif |
9132 | |
9133 | return Result; |
9134 | } |
9135 | |
9136 | bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS, |
9137 | ICmpInst::Predicate Pred, |
9138 | bool &Increasing) { |
9139 | |
9140 | // A zero step value for LHS means the induction variable is essentially a |
9141 | // loop invariant value. We don't really depend on the predicate actually |
9142 | // flipping from false to true (for increasing predicates, and the other way |
9143 | // around for decreasing predicates), all we care about is that *if* the |
9144 | // predicate changes then it only changes from false to true. |
9145 | // |
9146 | // A zero step value in itself is not very useful, but there may be places |
9147 | // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be |
9148 | // as general as possible. |
9149 | |
9150 | switch (Pred) { |
9151 | default: |
9152 | return false; // Conservative answer |
9153 | |
9154 | case ICmpInst::ICMP_UGT: |
9155 | case ICmpInst::ICMP_UGE: |
9156 | case ICmpInst::ICMP_ULT: |
9157 | case ICmpInst::ICMP_ULE: |
9158 | if (!LHS->hasNoUnsignedWrap()) |
9159 | return false; |
9160 | |
9161 | Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE; |
9162 | return true; |
9163 | |
9164 | case ICmpInst::ICMP_SGT: |
9165 | case ICmpInst::ICMP_SGE: |
9166 | case ICmpInst::ICMP_SLT: |
9167 | case ICmpInst::ICMP_SLE: { |
9168 | if (!LHS->hasNoSignedWrap()) |
9169 | return false; |
9170 | |
9171 | const SCEV *Step = LHS->getStepRecurrence(*this); |
9172 | |
9173 | if (isKnownNonNegative(Step)) { |
9174 | Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE; |
9175 | return true; |
9176 | } |
9177 | |
9178 | if (isKnownNonPositive(Step)) { |
9179 | Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE; |
9180 | return true; |
9181 | } |
9182 | |
9183 | return false; |
9184 | } |
9185 | |
9186 | } |
9187 | |
9188 | llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9188); |
9189 | } |
9190 | |
9191 | bool ScalarEvolution::isLoopInvariantPredicate( |
9192 | ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L, |
9193 | ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS, |
9194 | const SCEV *&InvariantRHS) { |
9195 | |
9196 | // If there is a loop-invariant, force it into the RHS, otherwise bail out. |
9197 | if (!isLoopInvariant(RHS, L)) { |
9198 | if (!isLoopInvariant(LHS, L)) |
9199 | return false; |
9200 | |
9201 | std::swap(LHS, RHS); |
9202 | Pred = ICmpInst::getSwappedPredicate(Pred); |
9203 | } |
9204 | |
9205 | const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS); |
9206 | if (!ArLHS || ArLHS->getLoop() != L) |
9207 | return false; |
9208 | |
9209 | bool Increasing; |
9210 | if (!isMonotonicPredicate(ArLHS, Pred, Increasing)) |
9211 | return false; |
9212 | |
9213 | // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to |
9214 | // true as the loop iterates, and the backedge is control dependent on |
9215 | // "ArLHS `Pred` RHS" == true then we can reason as follows: |
9216 | // |
9217 | // * if the predicate was false in the first iteration then the predicate |
9218 | // is never evaluated again, since the loop exits without taking the |
9219 | // backedge. |
9220 | // * if the predicate was true in the first iteration then it will |
9221 | // continue to be true for all future iterations since it is |
9222 | // monotonically increasing. |
9223 | // |
9224 | // For both the above possibilities, we can replace the loop varying |
9225 | // predicate with its value on the first iteration of the loop (which is |
9226 | // loop invariant). |
9227 | // |
9228 | // A similar reasoning applies for a monotonically decreasing predicate, by |
9229 | // replacing true with false and false with true in the above two bullets. |
9230 | |
9231 | auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred); |
9232 | |
9233 | if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS)) |
9234 | return false; |
9235 | |
9236 | InvariantPred = Pred; |
9237 | InvariantLHS = ArLHS->getStart(); |
9238 | InvariantRHS = RHS; |
9239 | return true; |
9240 | } |
9241 | |
9242 | bool ScalarEvolution::isKnownPredicateViaConstantRanges( |
9243 | ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) { |
9244 | if (HasSameValue(LHS, RHS)) |
9245 | return ICmpInst::isTrueWhenEqual(Pred); |
9246 | |
9247 | // This code is split out from isKnownPredicate because it is called from |
9248 | // within isLoopEntryGuardedByCond. |
9249 | |
9250 | auto CheckRanges = |
9251 | [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) { |
9252 | return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS) |
9253 | .contains(RangeLHS); |
9254 | }; |
9255 | |
9256 | // The check at the top of the function catches the case where the values are |
9257 | // known to be equal. |
9258 | if (Pred == CmpInst::ICMP_EQ) |
9259 | return false; |
9260 | |
9261 | if (Pred == CmpInst::ICMP_NE) |
9262 | return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) || |
9263 | CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) || |
9264 | isKnownNonZero(getMinusSCEV(LHS, RHS)); |
9265 | |
9266 | if (CmpInst::isSigned(Pred)) |
9267 | return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)); |
9268 | |
9269 | return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)); |
9270 | } |
9271 | |
9272 | bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred, |
9273 | const SCEV *LHS, |
9274 | const SCEV *RHS) { |
9275 | // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer. |
9276 | // Return Y via OutY. |
9277 | auto MatchBinaryAddToConst = |
9278 | [this](const SCEV *Result, const SCEV *X, APInt &OutY, |
9279 | SCEV::NoWrapFlags ExpectedFlags) { |
9280 | const SCEV *NonConstOp, *ConstOp; |
9281 | SCEV::NoWrapFlags FlagsPresent; |
9282 | |
9283 | if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) || |
9284 | !isa<SCEVConstant>(ConstOp) || NonConstOp != X) |
9285 | return false; |
9286 | |
9287 | OutY = cast<SCEVConstant>(ConstOp)->getAPInt(); |
9288 | return (FlagsPresent & ExpectedFlags) == ExpectedFlags; |
9289 | }; |
9290 | |
9291 | APInt C; |
9292 | |
9293 | switch (Pred) { |
9294 | default: |
9295 | break; |
9296 | |
9297 | case ICmpInst::ICMP_SGE: |
9298 | std::swap(LHS, RHS); |
9299 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
9300 | case ICmpInst::ICMP_SLE: |
9301 | // X s<= (X + C)<nsw> if C >= 0 |
9302 | if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative()) |
9303 | return true; |
9304 | |
9305 | // (X + C)<nsw> s<= X if C <= 0 |
9306 | if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && |
9307 | !C.isStrictlyPositive()) |
9308 | return true; |
9309 | break; |
9310 | |
9311 | case ICmpInst::ICMP_SGT: |
9312 | std::swap(LHS, RHS); |
9313 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
9314 | case ICmpInst::ICMP_SLT: |
9315 | // X s< (X + C)<nsw> if C > 0 |
9316 | if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && |
9317 | C.isStrictlyPositive()) |
9318 | return true; |
9319 | |
9320 | // (X + C)<nsw> s< X if C < 0 |
9321 | if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative()) |
9322 | return true; |
9323 | break; |
9324 | } |
9325 | |
9326 | return false; |
9327 | } |
9328 | |
9329 | bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred, |
9330 | const SCEV *LHS, |
9331 | const SCEV *RHS) { |
9332 | if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate) |
9333 | return false; |
9334 | |
9335 | // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on |
9336 | // the stack can result in exponential time complexity. |
9337 | SaveAndRestore<bool> Restore(ProvingSplitPredicate, true); |
9338 | |
9339 | // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L |
9340 | // |
9341 | // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use |
9342 | // isKnownPredicate. isKnownPredicate is more powerful, but also more |
9343 | // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the |
9344 | // interesting cases seen in practice. We can consider "upgrading" L >= 0 to |
9345 | // use isKnownPredicate later if needed. |
9346 | return isKnownNonNegative(RHS) && |
9347 | isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) && |
9348 | isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS); |
9349 | } |
9350 | |
9351 | bool ScalarEvolution::isImpliedViaGuard(BasicBlock *BB, |
9352 | ICmpInst::Predicate Pred, |
9353 | const SCEV *LHS, const SCEV *RHS) { |
9354 | // No need to even try if we know the module has no guards. |
9355 | if (!HasGuards) |
9356 | return false; |
9357 | |
9358 | return any_of(*BB, [&](Instruction &I) { |
9359 | using namespace llvm::PatternMatch; |
9360 | |
9361 | Value *Condition; |
9362 | return match(&I, m_Intrinsic<Intrinsic::experimental_guard>( |
9363 | m_Value(Condition))) && |
9364 | isImpliedCond(Pred, LHS, RHS, Condition, false); |
9365 | }); |
9366 | } |
9367 | |
9368 | /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is |
9369 | /// protected by a conditional between LHS and RHS. This is used to |
9370 | /// to eliminate casts. |
9371 | bool |
9372 | ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L, |
9373 | ICmpInst::Predicate Pred, |
9374 | const SCEV *LHS, const SCEV *RHS) { |
9375 | // Interpret a null as meaning no loop, where there is obviously no guard |
9376 | // (interprocedural conditions notwithstanding). |
9377 | if (!L) return true; |
9378 | |
9379 | if (VerifyIR) |
9380 | assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9381, __PRETTY_FUNCTION__)) |
9381 | "This cannot be done on broken IR!")((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9381, __PRETTY_FUNCTION__)); |
9382 | |
9383 | |
9384 | if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS)) |
9385 | return true; |
9386 | |
9387 | BasicBlock *Latch = L->getLoopLatch(); |
9388 | if (!Latch) |
9389 | return false; |
9390 | |
9391 | BranchInst *LoopContinuePredicate = |
9392 | dyn_cast<BranchInst>(Latch->getTerminator()); |
9393 | if (LoopContinuePredicate && LoopContinuePredicate->isConditional() && |
9394 | isImpliedCond(Pred, LHS, RHS, |
9395 | LoopContinuePredicate->getCondition(), |
9396 | LoopContinuePredicate->getSuccessor(0) != L->getHeader())) |
9397 | return true; |
9398 | |
9399 | // We don't want more than one activation of the following loops on the stack |
9400 | // -- that can lead to O(n!) time complexity. |
9401 | if (WalkingBEDominatingConds) |
9402 | return false; |
9403 | |
9404 | SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true); |
9405 | |
9406 | // See if we can exploit a trip count to prove the predicate. |
9407 | const auto &BETakenInfo = getBackedgeTakenInfo(L); |
9408 | const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this); |
9409 | if (LatchBECount != getCouldNotCompute()) { |
9410 | // We know that Latch branches back to the loop header exactly |
9411 | // LatchBECount times. This means the backdege condition at Latch is |
9412 | // equivalent to "{0,+,1} u< LatchBECount". |
9413 | Type *Ty = LatchBECount->getType(); |
9414 | auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW); |
9415 | const SCEV *LoopCounter = |
9416 | getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags); |
9417 | if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter, |
9418 | LatchBECount)) |
9419 | return true; |
9420 | } |
9421 | |
9422 | // Check conditions due to any @llvm.assume intrinsics. |
9423 | for (auto &AssumeVH : AC.assumptions()) { |
9424 | if (!AssumeVH) |
9425 | continue; |
9426 | auto *CI = cast<CallInst>(AssumeVH); |
9427 | if (!DT.dominates(CI, Latch->getTerminator())) |
9428 | continue; |
9429 | |
9430 | if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false)) |
9431 | return true; |
9432 | } |
9433 | |
9434 | // If the loop is not reachable from the entry block, we risk running into an |
9435 | // infinite loop as we walk up into the dom tree. These loops do not matter |
9436 | // anyway, so we just return a conservative answer when we see them. |
9437 | if (!DT.isReachableFromEntry(L->getHeader())) |
9438 | return false; |
9439 | |
9440 | if (isImpliedViaGuard(Latch, Pred, LHS, RHS)) |
9441 | return true; |
9442 | |
9443 | for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()]; |
9444 | DTN != HeaderDTN; DTN = DTN->getIDom()) { |
9445 | assert(DTN && "should reach the loop header before reaching the root!")((DTN && "should reach the loop header before reaching the root!" ) ? static_cast<void> (0) : __assert_fail ("DTN && \"should reach the loop header before reaching the root!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9445, __PRETTY_FUNCTION__)); |
9446 | |
9447 | BasicBlock *BB = DTN->getBlock(); |
9448 | if (isImpliedViaGuard(BB, Pred, LHS, RHS)) |
9449 | return true; |
9450 | |
9451 | BasicBlock *PBB = BB->getSinglePredecessor(); |
9452 | if (!PBB) |
9453 | continue; |
9454 | |
9455 | BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator()); |
9456 | if (!ContinuePredicate || !ContinuePredicate->isConditional()) |
9457 | continue; |
9458 | |
9459 | Value *Condition = ContinuePredicate->getCondition(); |
9460 | |
9461 | // If we have an edge `E` within the loop body that dominates the only |
9462 | // latch, the condition guarding `E` also guards the backedge. This |
9463 | // reasoning works only for loops with a single latch. |
9464 | |
9465 | BasicBlockEdge DominatingEdge(PBB, BB); |
9466 | if (DominatingEdge.isSingleEdge()) { |
9467 | // We're constructively (and conservatively) enumerating edges within the |
9468 | // loop body that dominate the latch. The dominator tree better agree |
9469 | // with us on this: |
9470 | assert(DT.dominates(DominatingEdge, Latch) && "should be!")((DT.dominates(DominatingEdge, Latch) && "should be!" ) ? static_cast<void> (0) : __assert_fail ("DT.dominates(DominatingEdge, Latch) && \"should be!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9470, __PRETTY_FUNCTION__)); |
9471 | |
9472 | if (isImpliedCond(Pred, LHS, RHS, Condition, |
9473 | BB != ContinuePredicate->getSuccessor(0))) |
9474 | return true; |
9475 | } |
9476 | } |
9477 | |
9478 | return false; |
9479 | } |
9480 | |
9481 | bool |
9482 | ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L, |
9483 | ICmpInst::Predicate Pred, |
9484 | const SCEV *LHS, const SCEV *RHS) { |
9485 | // Interpret a null as meaning no loop, where there is obviously no guard |
9486 | // (interprocedural conditions notwithstanding). |
9487 | if (!L) return false; |
9488 | |
9489 | if (VerifyIR) |
9490 | assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()) &&((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9491, __PRETTY_FUNCTION__)) |
9491 | "This cannot be done on broken IR!")((!verifyFunction(*L->getHeader()->getParent(), &dbgs ()) && "This cannot be done on broken IR!") ? static_cast <void> (0) : __assert_fail ("!verifyFunction(*L->getHeader()->getParent(), &dbgs()) && \"This cannot be done on broken IR!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9491, __PRETTY_FUNCTION__)); |
9492 | |
9493 | // Both LHS and RHS must be available at loop entry. |
9494 | assert(isAvailableAtLoopEntry(LHS, L) &&((isAvailableAtLoopEntry(LHS, L) && "LHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9495, __PRETTY_FUNCTION__)) |
9495 | "LHS is not available at Loop Entry")((isAvailableAtLoopEntry(LHS, L) && "LHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(LHS, L) && \"LHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9495, __PRETTY_FUNCTION__)); |
9496 | assert(isAvailableAtLoopEntry(RHS, L) &&((isAvailableAtLoopEntry(RHS, L) && "RHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9497, __PRETTY_FUNCTION__)) |
9497 | "RHS is not available at Loop Entry")((isAvailableAtLoopEntry(RHS, L) && "RHS is not available at Loop Entry" ) ? static_cast<void> (0) : __assert_fail ("isAvailableAtLoopEntry(RHS, L) && \"RHS is not available at Loop Entry\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9497, __PRETTY_FUNCTION__)); |
9498 | |
9499 | if (isKnownViaNonRecursiveReasoning(Pred, LHS, RHS)) |
9500 | return true; |
9501 | |
9502 | // If we cannot prove strict comparison (e.g. a > b), maybe we can prove |
9503 | // the facts (a >= b && a != b) separately. A typical situation is when the |
9504 | // non-strict comparison is known from ranges and non-equality is known from |
9505 | // dominating predicates. If we are proving strict comparison, we always try |
9506 | // to prove non-equality and non-strict comparison separately. |
9507 | auto NonStrictPredicate = ICmpInst::getNonStrictPredicate(Pred); |
9508 | const bool ProvingStrictComparison = (Pred != NonStrictPredicate); |
9509 | bool ProvedNonStrictComparison = false; |
9510 | bool ProvedNonEquality = false; |
9511 | |
9512 | if (ProvingStrictComparison) { |
9513 | ProvedNonStrictComparison = |
9514 | isKnownViaNonRecursiveReasoning(NonStrictPredicate, LHS, RHS); |
9515 | ProvedNonEquality = |
9516 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_NE, LHS, RHS); |
9517 | if (ProvedNonStrictComparison && ProvedNonEquality) |
9518 | return true; |
9519 | } |
9520 | |
9521 | // Try to prove (Pred, LHS, RHS) using isImpliedViaGuard. |
9522 | auto ProveViaGuard = [&](BasicBlock *Block) { |
9523 | if (isImpliedViaGuard(Block, Pred, LHS, RHS)) |
9524 | return true; |
9525 | if (ProvingStrictComparison) { |
9526 | if (!ProvedNonStrictComparison) |
9527 | ProvedNonStrictComparison = |
9528 | isImpliedViaGuard(Block, NonStrictPredicate, LHS, RHS); |
9529 | if (!ProvedNonEquality) |
9530 | ProvedNonEquality = |
9531 | isImpliedViaGuard(Block, ICmpInst::ICMP_NE, LHS, RHS); |
9532 | if (ProvedNonStrictComparison && ProvedNonEquality) |
9533 | return true; |
9534 | } |
9535 | return false; |
9536 | }; |
9537 | |
9538 | // Try to prove (Pred, LHS, RHS) using isImpliedCond. |
9539 | auto ProveViaCond = [&](Value *Condition, bool Inverse) { |
9540 | if (isImpliedCond(Pred, LHS, RHS, Condition, Inverse)) |
9541 | return true; |
9542 | if (ProvingStrictComparison) { |
9543 | if (!ProvedNonStrictComparison) |
9544 | ProvedNonStrictComparison = |
9545 | isImpliedCond(NonStrictPredicate, LHS, RHS, Condition, Inverse); |
9546 | if (!ProvedNonEquality) |
9547 | ProvedNonEquality = |
9548 | isImpliedCond(ICmpInst::ICMP_NE, LHS, RHS, Condition, Inverse); |
9549 | if (ProvedNonStrictComparison && ProvedNonEquality) |
9550 | return true; |
9551 | } |
9552 | return false; |
9553 | }; |
9554 | |
9555 | // Starting at the loop predecessor, climb up the predecessor chain, as long |
9556 | // as there are predecessors that can be found that have unique successors |
9557 | // leading to the original header. |
9558 | for (std::pair<BasicBlock *, BasicBlock *> |
9559 | Pair(L->getLoopPredecessor(), L->getHeader()); |
9560 | Pair.first; |
9561 | Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) { |
9562 | |
9563 | if (ProveViaGuard(Pair.first)) |
9564 | return true; |
9565 | |
9566 | BranchInst *LoopEntryPredicate = |
9567 | dyn_cast<BranchInst>(Pair.first->getTerminator()); |
9568 | if (!LoopEntryPredicate || |
9569 | LoopEntryPredicate->isUnconditional()) |
9570 | continue; |
9571 | |
9572 | if (ProveViaCond(LoopEntryPredicate->getCondition(), |
9573 | LoopEntryPredicate->getSuccessor(0) != Pair.second)) |
9574 | return true; |
9575 | } |
9576 | |
9577 | // Check conditions due to any @llvm.assume intrinsics. |
9578 | for (auto &AssumeVH : AC.assumptions()) { |
9579 | if (!AssumeVH) |
9580 | continue; |
9581 | auto *CI = cast<CallInst>(AssumeVH); |
9582 | if (!DT.dominates(CI, L->getHeader())) |
9583 | continue; |
9584 | |
9585 | if (ProveViaCond(CI->getArgOperand(0), false)) |
9586 | return true; |
9587 | } |
9588 | |
9589 | return false; |
9590 | } |
9591 | |
9592 | bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, |
9593 | const SCEV *LHS, const SCEV *RHS, |
9594 | Value *FoundCondValue, |
9595 | bool Inverse) { |
9596 | if (!PendingLoopPredicates.insert(FoundCondValue).second) |
9597 | return false; |
9598 | |
9599 | auto ClearOnExit = |
9600 | make_scope_exit([&]() { PendingLoopPredicates.erase(FoundCondValue); }); |
9601 | |
9602 | // Recursively handle And and Or conditions. |
9603 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) { |
9604 | if (BO->getOpcode() == Instruction::And) { |
9605 | if (!Inverse) |
9606 | return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) || |
9607 | isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse); |
9608 | } else if (BO->getOpcode() == Instruction::Or) { |
9609 | if (Inverse) |
9610 | return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) || |
9611 | isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse); |
9612 | } |
9613 | } |
9614 | |
9615 | ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue); |
9616 | if (!ICI) return false; |
9617 | |
9618 | // Now that we found a conditional branch that dominates the loop or controls |
9619 | // the loop latch. Check to see if it is the comparison we are looking for. |
9620 | ICmpInst::Predicate FoundPred; |
9621 | if (Inverse) |
9622 | FoundPred = ICI->getInversePredicate(); |
9623 | else |
9624 | FoundPred = ICI->getPredicate(); |
9625 | |
9626 | const SCEV *FoundLHS = getSCEV(ICI->getOperand(0)); |
9627 | const SCEV *FoundRHS = getSCEV(ICI->getOperand(1)); |
9628 | |
9629 | return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS); |
9630 | } |
9631 | |
9632 | bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS, |
9633 | const SCEV *RHS, |
9634 | ICmpInst::Predicate FoundPred, |
9635 | const SCEV *FoundLHS, |
9636 | const SCEV *FoundRHS) { |
9637 | // Balance the types. |
9638 | if (getTypeSizeInBits(LHS->getType()) < |
9639 | getTypeSizeInBits(FoundLHS->getType())) { |
9640 | if (CmpInst::isSigned(Pred)) { |
9641 | LHS = getSignExtendExpr(LHS, FoundLHS->getType()); |
9642 | RHS = getSignExtendExpr(RHS, FoundLHS->getType()); |
9643 | } else { |
9644 | LHS = getZeroExtendExpr(LHS, FoundLHS->getType()); |
9645 | RHS = getZeroExtendExpr(RHS, FoundLHS->getType()); |
9646 | } |
9647 | } else if (getTypeSizeInBits(LHS->getType()) > |
9648 | getTypeSizeInBits(FoundLHS->getType())) { |
9649 | if (CmpInst::isSigned(FoundPred)) { |
9650 | FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType()); |
9651 | FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType()); |
9652 | } else { |
9653 | FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType()); |
9654 | FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType()); |
9655 | } |
9656 | } |
9657 | |
9658 | // Canonicalize the query to match the way instcombine will have |
9659 | // canonicalized the comparison. |
9660 | if (SimplifyICmpOperands(Pred, LHS, RHS)) |
9661 | if (LHS == RHS) |
9662 | return CmpInst::isTrueWhenEqual(Pred); |
9663 | if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS)) |
9664 | if (FoundLHS == FoundRHS) |
9665 | return CmpInst::isFalseWhenEqual(FoundPred); |
9666 | |
9667 | // Check to see if we can make the LHS or RHS match. |
9668 | if (LHS == FoundRHS || RHS == FoundLHS) { |
9669 | if (isa<SCEVConstant>(RHS)) { |
9670 | std::swap(FoundLHS, FoundRHS); |
9671 | FoundPred = ICmpInst::getSwappedPredicate(FoundPred); |
9672 | } else { |
9673 | std::swap(LHS, RHS); |
9674 | Pred = ICmpInst::getSwappedPredicate(Pred); |
9675 | } |
9676 | } |
9677 | |
9678 | // Check whether the found predicate is the same as the desired predicate. |
9679 | if (FoundPred == Pred) |
9680 | return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS); |
9681 | |
9682 | // Check whether swapping the found predicate makes it the same as the |
9683 | // desired predicate. |
9684 | if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) { |
9685 | if (isa<SCEVConstant>(RHS)) |
9686 | return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS); |
9687 | else |
9688 | return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred), |
9689 | RHS, LHS, FoundLHS, FoundRHS); |
9690 | } |
9691 | |
9692 | // Unsigned comparison is the same as signed comparison when both the operands |
9693 | // are non-negative. |
9694 | if (CmpInst::isUnsigned(FoundPred) && |
9695 | CmpInst::getSignedPredicate(FoundPred) == Pred && |
9696 | isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS)) |
9697 | return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS); |
9698 | |
9699 | // Check if we can make progress by sharpening ranges. |
9700 | if (FoundPred == ICmpInst::ICMP_NE && |
9701 | (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) { |
9702 | |
9703 | const SCEVConstant *C = nullptr; |
9704 | const SCEV *V = nullptr; |
9705 | |
9706 | if (isa<SCEVConstant>(FoundLHS)) { |
9707 | C = cast<SCEVConstant>(FoundLHS); |
9708 | V = FoundRHS; |
9709 | } else { |
9710 | C = cast<SCEVConstant>(FoundRHS); |
9711 | V = FoundLHS; |
9712 | } |
9713 | |
9714 | // The guarding predicate tells us that C != V. If the known range |
9715 | // of V is [C, t), we can sharpen the range to [C + 1, t). The |
9716 | // range we consider has to correspond to same signedness as the |
9717 | // predicate we're interested in folding. |
9718 | |
9719 | APInt Min = ICmpInst::isSigned(Pred) ? |
9720 | getSignedRangeMin(V) : getUnsignedRangeMin(V); |
9721 | |
9722 | if (Min == C->getAPInt()) { |
9723 | // Given (V >= Min && V != Min) we conclude V >= (Min + 1). |
9724 | // This is true even if (Min + 1) wraps around -- in case of |
9725 | // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)). |
9726 | |
9727 | APInt SharperMin = Min + 1; |
9728 | |
9729 | switch (Pred) { |
9730 | case ICmpInst::ICMP_SGE: |
9731 | case ICmpInst::ICMP_UGE: |
9732 | // We know V `Pred` SharperMin. If this implies LHS `Pred` |
9733 | // RHS, we're done. |
9734 | if (isImpliedCondOperands(Pred, LHS, RHS, V, |
9735 | getConstant(SharperMin))) |
9736 | return true; |
9737 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
9738 | |
9739 | case ICmpInst::ICMP_SGT: |
9740 | case ICmpInst::ICMP_UGT: |
9741 | // We know from the range information that (V `Pred` Min || |
9742 | // V == Min). We know from the guarding condition that !(V |
9743 | // == Min). This gives us |
9744 | // |
9745 | // V `Pred` Min || V == Min && !(V == Min) |
9746 | // => V `Pred` Min |
9747 | // |
9748 | // If V `Pred` Min implies LHS `Pred` RHS, we're done. |
9749 | |
9750 | if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min))) |
9751 | return true; |
9752 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
9753 | |
9754 | default: |
9755 | // No change |
9756 | break; |
9757 | } |
9758 | } |
9759 | } |
9760 | |
9761 | // Check whether the actual condition is beyond sufficient. |
9762 | if (FoundPred == ICmpInst::ICMP_EQ) |
9763 | if (ICmpInst::isTrueWhenEqual(Pred)) |
9764 | if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS)) |
9765 | return true; |
9766 | if (Pred == ICmpInst::ICMP_NE) |
9767 | if (!ICmpInst::isTrueWhenEqual(FoundPred)) |
9768 | if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS)) |
9769 | return true; |
9770 | |
9771 | // Otherwise assume the worst. |
9772 | return false; |
9773 | } |
9774 | |
9775 | bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr, |
9776 | const SCEV *&L, const SCEV *&R, |
9777 | SCEV::NoWrapFlags &Flags) { |
9778 | const auto *AE = dyn_cast<SCEVAddExpr>(Expr); |
9779 | if (!AE || AE->getNumOperands() != 2) |
9780 | return false; |
9781 | |
9782 | L = AE->getOperand(0); |
9783 | R = AE->getOperand(1); |
9784 | Flags = AE->getNoWrapFlags(); |
9785 | return true; |
9786 | } |
9787 | |
9788 | Optional<APInt> ScalarEvolution::computeConstantDifference(const SCEV *More, |
9789 | const SCEV *Less) { |
9790 | // We avoid subtracting expressions here because this function is usually |
9791 | // fairly deep in the call stack (i.e. is called many times). |
9792 | |
9793 | if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) { |
9794 | const auto *LAR = cast<SCEVAddRecExpr>(Less); |
9795 | const auto *MAR = cast<SCEVAddRecExpr>(More); |
9796 | |
9797 | if (LAR->getLoop() != MAR->getLoop()) |
9798 | return None; |
9799 | |
9800 | // We look at affine expressions only; not for correctness but to keep |
9801 | // getStepRecurrence cheap. |
9802 | if (!LAR->isAffine() || !MAR->isAffine()) |
9803 | return None; |
9804 | |
9805 | if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this)) |
9806 | return None; |
9807 | |
9808 | Less = LAR->getStart(); |
9809 | More = MAR->getStart(); |
9810 | |
9811 | // fall through |
9812 | } |
9813 | |
9814 | if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) { |
9815 | const auto &M = cast<SCEVConstant>(More)->getAPInt(); |
9816 | const auto &L = cast<SCEVConstant>(Less)->getAPInt(); |
9817 | return M - L; |
9818 | } |
9819 | |
9820 | SCEV::NoWrapFlags Flags; |
9821 | const SCEV *LLess = nullptr, *RLess = nullptr; |
9822 | const SCEV *LMore = nullptr, *RMore = nullptr; |
9823 | const SCEVConstant *C1 = nullptr, *C2 = nullptr; |
9824 | // Compare (X + C1) vs X. |
9825 | if (splitBinaryAdd(Less, LLess, RLess, Flags)) |
9826 | if ((C1 = dyn_cast<SCEVConstant>(LLess))) |
9827 | if (RLess == More) |
9828 | return -(C1->getAPInt()); |
9829 | |
9830 | // Compare X vs (X + C2). |
9831 | if (splitBinaryAdd(More, LMore, RMore, Flags)) |
9832 | if ((C2 = dyn_cast<SCEVConstant>(LMore))) |
9833 | if (RMore == Less) |
9834 | return C2->getAPInt(); |
9835 | |
9836 | // Compare (X + C1) vs (X + C2). |
9837 | if (C1 && C2 && RLess == RMore) |
9838 | return C2->getAPInt() - C1->getAPInt(); |
9839 | |
9840 | return None; |
9841 | } |
9842 | |
9843 | bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow( |
9844 | ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, |
9845 | const SCEV *FoundLHS, const SCEV *FoundRHS) { |
9846 | if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT) |
9847 | return false; |
9848 | |
9849 | const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS); |
9850 | if (!AddRecLHS) |
9851 | return false; |
9852 | |
9853 | const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS); |
9854 | if (!AddRecFoundLHS) |
9855 | return false; |
9856 | |
9857 | // We'd like to let SCEV reason about control dependencies, so we constrain |
9858 | // both the inequalities to be about add recurrences on the same loop. This |
9859 | // way we can use isLoopEntryGuardedByCond later. |
9860 | |
9861 | const Loop *L = AddRecFoundLHS->getLoop(); |
9862 | if (L != AddRecLHS->getLoop()) |
9863 | return false; |
9864 | |
9865 | // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1) |
9866 | // |
9867 | // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C) |
9868 | // ... (2) |
9869 | // |
9870 | // Informal proof for (2), assuming (1) [*]: |
9871 | // |
9872 | // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**] |
9873 | // |
9874 | // Then |
9875 | // |
9876 | // FoundLHS s< FoundRHS s< INT_MIN - C |
9877 | // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ] |
9878 | // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ] |
9879 | // <=> (FoundLHS + INT_MIN + C + INT_MIN) s< |
9880 | // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ] |
9881 | // <=> FoundLHS + C s< FoundRHS + C |
9882 | // |
9883 | // [*]: (1) can be proved by ruling out overflow. |
9884 | // |
9885 | // [**]: This can be proved by analyzing all the four possibilities: |
9886 | // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and |
9887 | // (A s>= 0, B s>= 0). |
9888 | // |
9889 | // Note: |
9890 | // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C" |
9891 | // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS |
9892 | // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS |
9893 | // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is |
9894 | // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS + |
9895 | // C)". |
9896 | |
9897 | Optional<APInt> LDiff = computeConstantDifference(LHS, FoundLHS); |
9898 | Optional<APInt> RDiff = computeConstantDifference(RHS, FoundRHS); |
9899 | if (!LDiff || !RDiff || *LDiff != *RDiff) |
9900 | return false; |
9901 | |
9902 | if (LDiff->isMinValue()) |
9903 | return true; |
9904 | |
9905 | APInt FoundRHSLimit; |
9906 | |
9907 | if (Pred == CmpInst::ICMP_ULT) { |
9908 | FoundRHSLimit = -(*RDiff); |
9909 | } else { |
9910 | assert(Pred == CmpInst::ICMP_SLT && "Checked above!")((Pred == CmpInst::ICMP_SLT && "Checked above!") ? static_cast <void> (0) : __assert_fail ("Pred == CmpInst::ICMP_SLT && \"Checked above!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9910, __PRETTY_FUNCTION__)); |
9911 | FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - *RDiff; |
9912 | } |
9913 | |
9914 | // Try to prove (1) or (2), as needed. |
9915 | return isAvailableAtLoopEntry(FoundRHS, L) && |
9916 | isLoopEntryGuardedByCond(L, Pred, FoundRHS, |
9917 | getConstant(FoundRHSLimit)); |
9918 | } |
9919 | |
9920 | bool ScalarEvolution::isImpliedViaMerge(ICmpInst::Predicate Pred, |
9921 | const SCEV *LHS, const SCEV *RHS, |
9922 | const SCEV *FoundLHS, |
9923 | const SCEV *FoundRHS, unsigned Depth) { |
9924 | const PHINode *LPhi = nullptr, *RPhi = nullptr; |
9925 | |
9926 | auto ClearOnExit = make_scope_exit([&]() { |
9927 | if (LPhi) { |
9928 | bool Erased = PendingMerges.erase(LPhi); |
9929 | assert(Erased && "Failed to erase LPhi!")((Erased && "Failed to erase LPhi!") ? static_cast< void> (0) : __assert_fail ("Erased && \"Failed to erase LPhi!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9929, __PRETTY_FUNCTION__)); |
9930 | (void)Erased; |
9931 | } |
9932 | if (RPhi) { |
9933 | bool Erased = PendingMerges.erase(RPhi); |
9934 | assert(Erased && "Failed to erase RPhi!")((Erased && "Failed to erase RPhi!") ? static_cast< void> (0) : __assert_fail ("Erased && \"Failed to erase RPhi!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9934, __PRETTY_FUNCTION__)); |
9935 | (void)Erased; |
9936 | } |
9937 | }); |
9938 | |
9939 | // Find respective Phis and check that they are not being pending. |
9940 | if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS)) |
9941 | if (auto *Phi = dyn_cast<PHINode>(LU->getValue())) { |
9942 | if (!PendingMerges.insert(Phi).second) |
9943 | return false; |
9944 | LPhi = Phi; |
9945 | } |
9946 | if (const SCEVUnknown *RU = dyn_cast<SCEVUnknown>(RHS)) |
9947 | if (auto *Phi = dyn_cast<PHINode>(RU->getValue())) { |
9948 | // If we detect a loop of Phi nodes being processed by this method, for |
9949 | // example: |
9950 | // |
9951 | // %a = phi i32 [ %some1, %preheader ], [ %b, %latch ] |
9952 | // %b = phi i32 [ %some2, %preheader ], [ %a, %latch ] |
9953 | // |
9954 | // we don't want to deal with a case that complex, so return conservative |
9955 | // answer false. |
9956 | if (!PendingMerges.insert(Phi).second) |
9957 | return false; |
9958 | RPhi = Phi; |
9959 | } |
9960 | |
9961 | // If none of LHS, RHS is a Phi, nothing to do here. |
9962 | if (!LPhi && !RPhi) |
9963 | return false; |
9964 | |
9965 | // If there is a SCEVUnknown Phi we are interested in, make it left. |
9966 | if (!LPhi) { |
9967 | std::swap(LHS, RHS); |
9968 | std::swap(FoundLHS, FoundRHS); |
9969 | std::swap(LPhi, RPhi); |
9970 | Pred = ICmpInst::getSwappedPredicate(Pred); |
9971 | } |
9972 | |
9973 | assert(LPhi && "LPhi should definitely be a SCEVUnknown Phi!")((LPhi && "LPhi should definitely be a SCEVUnknown Phi!" ) ? static_cast<void> (0) : __assert_fail ("LPhi && \"LPhi should definitely be a SCEVUnknown Phi!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 9973, __PRETTY_FUNCTION__)); |
9974 | const BasicBlock *LBB = LPhi->getParent(); |
9975 | const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS); |
9976 | |
9977 | auto ProvedEasily = [&](const SCEV *S1, const SCEV *S2) { |
9978 | return isKnownViaNonRecursiveReasoning(Pred, S1, S2) || |
9979 | isImpliedCondOperandsViaRanges(Pred, S1, S2, FoundLHS, FoundRHS) || |
9980 | isImpliedViaOperations(Pred, S1, S2, FoundLHS, FoundRHS, Depth); |
9981 | }; |
9982 | |
9983 | if (RPhi && RPhi->getParent() == LBB) { |
9984 | // Case one: RHS is also a SCEVUnknown Phi from the same basic block. |
9985 | // If we compare two Phis from the same block, and for each entry block |
9986 | // the predicate is true for incoming values from this block, then the |
9987 | // predicate is also true for the Phis. |
9988 | for (const BasicBlock *IncBB : predecessors(LBB)) { |
9989 | const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB)); |
9990 | const SCEV *R = getSCEV(RPhi->getIncomingValueForBlock(IncBB)); |
9991 | if (!ProvedEasily(L, R)) |
9992 | return false; |
9993 | } |
9994 | } else if (RAR && RAR->getLoop()->getHeader() == LBB) { |
9995 | // Case two: RHS is also a Phi from the same basic block, and it is an |
9996 | // AddRec. It means that there is a loop which has both AddRec and Unknown |
9997 | // PHIs, for it we can compare incoming values of AddRec from above the loop |
9998 | // and latch with their respective incoming values of LPhi. |
9999 | // TODO: Generalize to handle loops with many inputs in a header. |
10000 | if (LPhi->getNumIncomingValues() != 2) return false; |
10001 | |
10002 | auto *RLoop = RAR->getLoop(); |
10003 | auto *Predecessor = RLoop->getLoopPredecessor(); |
10004 | assert(Predecessor && "Loop with AddRec with no predecessor?")((Predecessor && "Loop with AddRec with no predecessor?" ) ? static_cast<void> (0) : __assert_fail ("Predecessor && \"Loop with AddRec with no predecessor?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10004, __PRETTY_FUNCTION__)); |
10005 | const SCEV *L1 = getSCEV(LPhi->getIncomingValueForBlock(Predecessor)); |
10006 | if (!ProvedEasily(L1, RAR->getStart())) |
10007 | return false; |
10008 | auto *Latch = RLoop->getLoopLatch(); |
10009 | assert(Latch && "Loop with AddRec with no latch?")((Latch && "Loop with AddRec with no latch?") ? static_cast <void> (0) : __assert_fail ("Latch && \"Loop with AddRec with no latch?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10009, __PRETTY_FUNCTION__)); |
10010 | const SCEV *L2 = getSCEV(LPhi->getIncomingValueForBlock(Latch)); |
10011 | if (!ProvedEasily(L2, RAR->getPostIncExpr(*this))) |
10012 | return false; |
10013 | } else { |
10014 | // In all other cases go over inputs of LHS and compare each of them to RHS, |
10015 | // the predicate is true for (LHS, RHS) if it is true for all such pairs. |
10016 | // At this point RHS is either a non-Phi, or it is a Phi from some block |
10017 | // different from LBB. |
10018 | for (const BasicBlock *IncBB : predecessors(LBB)) { |
10019 | // Check that RHS is available in this block. |
10020 | if (!dominates(RHS, IncBB)) |
10021 | return false; |
10022 | const SCEV *L = getSCEV(LPhi->getIncomingValueForBlock(IncBB)); |
10023 | if (!ProvedEasily(L, RHS)) |
10024 | return false; |
10025 | } |
10026 | } |
10027 | return true; |
10028 | } |
10029 | |
10030 | bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred, |
10031 | const SCEV *LHS, const SCEV *RHS, |
10032 | const SCEV *FoundLHS, |
10033 | const SCEV *FoundRHS) { |
10034 | if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS)) |
10035 | return true; |
10036 | |
10037 | if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS)) |
10038 | return true; |
10039 | |
10040 | return isImpliedCondOperandsHelper(Pred, LHS, RHS, |
10041 | FoundLHS, FoundRHS) || |
10042 | // ~x < ~y --> x > y |
10043 | isImpliedCondOperandsHelper(Pred, LHS, RHS, |
10044 | getNotSCEV(FoundRHS), |
10045 | getNotSCEV(FoundLHS)); |
10046 | } |
10047 | |
10048 | /// If Expr computes ~A, return A else return nullptr |
10049 | static const SCEV *MatchNotExpr(const SCEV *Expr) { |
10050 | const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr); |
10051 | if (!Add || Add->getNumOperands() != 2 || |
10052 | !Add->getOperand(0)->isAllOnesValue()) |
10053 | return nullptr; |
10054 | |
10055 | const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1)); |
10056 | if (!AddRHS || AddRHS->getNumOperands() != 2 || |
10057 | !AddRHS->getOperand(0)->isAllOnesValue()) |
10058 | return nullptr; |
10059 | |
10060 | return AddRHS->getOperand(1); |
10061 | } |
10062 | |
10063 | /// Is MaybeMaxExpr an SMax or UMax of Candidate and some other values? |
10064 | template<typename MaxExprType> |
10065 | static bool IsMaxConsistingOf(const SCEV *MaybeMaxExpr, |
10066 | const SCEV *Candidate) { |
10067 | const MaxExprType *MaxExpr = dyn_cast<MaxExprType>(MaybeMaxExpr); |
10068 | if (!MaxExpr) return false; |
10069 | |
10070 | return find(MaxExpr->operands(), Candidate) != MaxExpr->op_end(); |
10071 | } |
10072 | |
10073 | /// Is MaybeMinExpr an SMin or UMin of Candidate and some other values? |
10074 | template<typename MaxExprType> |
10075 | static bool IsMinConsistingOf(ScalarEvolution &SE, |
10076 | const SCEV *MaybeMinExpr, |
10077 | const SCEV *Candidate) { |
10078 | const SCEV *MaybeMaxExpr = MatchNotExpr(MaybeMinExpr); |
10079 | if (!MaybeMaxExpr) |
10080 | return false; |
10081 | |
10082 | return IsMaxConsistingOf<MaxExprType>(MaybeMaxExpr, SE.getNotSCEV(Candidate)); |
10083 | } |
10084 | |
10085 | static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE, |
10086 | ICmpInst::Predicate Pred, |
10087 | const SCEV *LHS, const SCEV *RHS) { |
10088 | // If both sides are affine addrecs for the same loop, with equal |
10089 | // steps, and we know the recurrences don't wrap, then we only |
10090 | // need to check the predicate on the starting values. |
10091 | |
10092 | if (!ICmpInst::isRelational(Pred)) |
10093 | return false; |
10094 | |
10095 | const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS); |
10096 | if (!LAR) |
10097 | return false; |
10098 | const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS); |
10099 | if (!RAR) |
10100 | return false; |
10101 | if (LAR->getLoop() != RAR->getLoop()) |
10102 | return false; |
10103 | if (!LAR->isAffine() || !RAR->isAffine()) |
10104 | return false; |
10105 | |
10106 | if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE)) |
10107 | return false; |
10108 | |
10109 | SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ? |
10110 | SCEV::FlagNSW : SCEV::FlagNUW; |
10111 | if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW)) |
10112 | return false; |
10113 | |
10114 | return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart()); |
10115 | } |
10116 | |
10117 | /// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max |
10118 | /// expression? |
10119 | static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE, |
10120 | ICmpInst::Predicate Pred, |
10121 | const SCEV *LHS, const SCEV *RHS) { |
10122 | switch (Pred) { |
10123 | default: |
10124 | return false; |
10125 | |
10126 | case ICmpInst::ICMP_SGE: |
10127 | std::swap(LHS, RHS); |
10128 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
10129 | case ICmpInst::ICMP_SLE: |
10130 | return |
10131 | // min(A, ...) <= A |
10132 | IsMinConsistingOf<SCEVSMaxExpr>(SE, LHS, RHS) || |
10133 | // A <= max(A, ...) |
10134 | IsMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS); |
10135 | |
10136 | case ICmpInst::ICMP_UGE: |
10137 | std::swap(LHS, RHS); |
10138 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
10139 | case ICmpInst::ICMP_ULE: |
10140 | return |
10141 | // min(A, ...) <= A |
10142 | IsMinConsistingOf<SCEVUMaxExpr>(SE, LHS, RHS) || |
10143 | // A <= max(A, ...) |
10144 | IsMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS); |
10145 | } |
10146 | |
10147 | llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10147); |
10148 | } |
10149 | |
10150 | bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred, |
10151 | const SCEV *LHS, const SCEV *RHS, |
10152 | const SCEV *FoundLHS, |
10153 | const SCEV *FoundRHS, |
10154 | unsigned Depth) { |
10155 | assert(getTypeSizeInBits(LHS->getType()) ==((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS ->getType()) && "LHS and RHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10157, __PRETTY_FUNCTION__)) |
10156 | getTypeSizeInBits(RHS->getType()) &&((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS ->getType()) && "LHS and RHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10157, __PRETTY_FUNCTION__)) |
10157 | "LHS and RHS have different sizes?")((getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS ->getType()) && "LHS and RHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(LHS->getType()) == getTypeSizeInBits(RHS->getType()) && \"LHS and RHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10157, __PRETTY_FUNCTION__)); |
10158 | assert(getTypeSizeInBits(FoundLHS->getType()) ==((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits (FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10160, __PRETTY_FUNCTION__)) |
10159 | getTypeSizeInBits(FoundRHS->getType()) &&((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits (FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10160, __PRETTY_FUNCTION__)) |
10160 | "FoundLHS and FoundRHS have different sizes?")((getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits (FoundRHS->getType()) && "FoundLHS and FoundRHS have different sizes?" ) ? static_cast<void> (0) : __assert_fail ("getTypeSizeInBits(FoundLHS->getType()) == getTypeSizeInBits(FoundRHS->getType()) && \"FoundLHS and FoundRHS have different sizes?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10160, __PRETTY_FUNCTION__)); |
10161 | // We want to avoid hurting the compile time with analysis of too big trees. |
10162 | if (Depth > MaxSCEVOperationsImplicationDepth) |
10163 | return false; |
10164 | // We only want to work with ICMP_SGT comparison so far. |
10165 | // TODO: Extend to ICMP_UGT? |
10166 | if (Pred == ICmpInst::ICMP_SLT) { |
10167 | Pred = ICmpInst::ICMP_SGT; |
10168 | std::swap(LHS, RHS); |
10169 | std::swap(FoundLHS, FoundRHS); |
10170 | } |
10171 | if (Pred != ICmpInst::ICMP_SGT) |
10172 | return false; |
10173 | |
10174 | auto GetOpFromSExt = [&](const SCEV *S) { |
10175 | if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S)) |
10176 | return Ext->getOperand(); |
10177 | // TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off |
10178 | // the constant in some cases. |
10179 | return S; |
10180 | }; |
10181 | |
10182 | // Acquire values from extensions. |
10183 | auto *OrigLHS = LHS; |
10184 | auto *OrigFoundLHS = FoundLHS; |
10185 | LHS = GetOpFromSExt(LHS); |
10186 | FoundLHS = GetOpFromSExt(FoundLHS); |
10187 | |
10188 | // Is the SGT predicate can be proved trivially or using the found context. |
10189 | auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) { |
10190 | return isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGT, S1, S2) || |
10191 | isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS, |
10192 | FoundRHS, Depth + 1); |
10193 | }; |
10194 | |
10195 | if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) { |
10196 | // We want to avoid creation of any new non-constant SCEV. Since we are |
10197 | // going to compare the operands to RHS, we should be certain that we don't |
10198 | // need any size extensions for this. So let's decline all cases when the |
10199 | // sizes of types of LHS and RHS do not match. |
10200 | // TODO: Maybe try to get RHS from sext to catch more cases? |
10201 | if (getTypeSizeInBits(LHS->getType()) != getTypeSizeInBits(RHS->getType())) |
10202 | return false; |
10203 | |
10204 | // Should not overflow. |
10205 | if (!LHSAddExpr->hasNoSignedWrap()) |
10206 | return false; |
10207 | |
10208 | auto *LL = LHSAddExpr->getOperand(0); |
10209 | auto *LR = LHSAddExpr->getOperand(1); |
10210 | auto *MinusOne = getNegativeSCEV(getOne(RHS->getType())); |
10211 | |
10212 | // Checks that S1 >= 0 && S2 > RHS, trivially or using the found context. |
10213 | auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) { |
10214 | return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS); |
10215 | }; |
10216 | // Try to prove the following rule: |
10217 | // (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS). |
10218 | // (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS). |
10219 | if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL)) |
10220 | return true; |
10221 | } else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) { |
10222 | Value *LL, *LR; |
10223 | // FIXME: Once we have SDiv implemented, we can get rid of this matching. |
10224 | |
10225 | using namespace llvm::PatternMatch; |
10226 | |
10227 | if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) { |
10228 | // Rules for division. |
10229 | // We are going to perform some comparisons with Denominator and its |
10230 | // derivative expressions. In general case, creating a SCEV for it may |
10231 | // lead to a complex analysis of the entire graph, and in particular it |
10232 | // can request trip count recalculation for the same loop. This would |
10233 | // cache as SCEVCouldNotCompute to avoid the infinite recursion. To avoid |
10234 | // this, we only want to create SCEVs that are constants in this section. |
10235 | // So we bail if Denominator is not a constant. |
10236 | if (!isa<ConstantInt>(LR)) |
10237 | return false; |
10238 | |
10239 | auto *Denominator = cast<SCEVConstant>(getSCEV(LR)); |
10240 | |
10241 | // We want to make sure that LHS = FoundLHS / Denominator. If it is so, |
10242 | // then a SCEV for the numerator already exists and matches with FoundLHS. |
10243 | auto *Numerator = getExistingSCEV(LL); |
10244 | if (!Numerator || Numerator->getType() != FoundLHS->getType()) |
10245 | return false; |
10246 | |
10247 | // Make sure that the numerator matches with FoundLHS and the denominator |
10248 | // is positive. |
10249 | if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator)) |
10250 | return false; |
10251 | |
10252 | auto *DTy = Denominator->getType(); |
10253 | auto *FRHSTy = FoundRHS->getType(); |
10254 | if (DTy->isPointerTy() != FRHSTy->isPointerTy()) |
10255 | // One of types is a pointer and another one is not. We cannot extend |
10256 | // them properly to a wider type, so let us just reject this case. |
10257 | // TODO: Usage of getEffectiveSCEVType for DTy, FRHSTy etc should help |
10258 | // to avoid this check. |
10259 | return false; |
10260 | |
10261 | // Given that: |
10262 | // FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0. |
10263 | auto *WTy = getWiderType(DTy, FRHSTy); |
10264 | auto *DenominatorExt = getNoopOrSignExtend(Denominator, WTy); |
10265 | auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, WTy); |
10266 | |
10267 | // Try to prove the following rule: |
10268 | // (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS). |
10269 | // For example, given that FoundLHS > 2. It means that FoundLHS is at |
10270 | // least 3. If we divide it by Denominator < 4, we will have at least 1. |
10271 | auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(WTy, 2)); |
10272 | if (isKnownNonPositive(RHS) && |
10273 | IsSGTViaContext(FoundRHSExt, DenomMinusTwo)) |
10274 | return true; |
10275 | |
10276 | // Try to prove the following rule: |
10277 | // (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS). |
10278 | // For example, given that FoundLHS > -3. Then FoundLHS is at least -2. |
10279 | // If we divide it by Denominator > 2, then: |
10280 | // 1. If FoundLHS is negative, then the result is 0. |
10281 | // 2. If FoundLHS is non-negative, then the result is non-negative. |
10282 | // Anyways, the result is non-negative. |
10283 | auto *MinusOne = getNegativeSCEV(getOne(WTy)); |
10284 | auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt); |
10285 | if (isKnownNegative(RHS) && |
10286 | IsSGTViaContext(FoundRHSExt, NegDenomMinusOne)) |
10287 | return true; |
10288 | } |
10289 | } |
10290 | |
10291 | // If our expression contained SCEVUnknown Phis, and we split it down and now |
10292 | // need to prove something for them, try to prove the predicate for every |
10293 | // possible incoming values of those Phis. |
10294 | if (isImpliedViaMerge(Pred, OrigLHS, RHS, OrigFoundLHS, FoundRHS, Depth + 1)) |
10295 | return true; |
10296 | |
10297 | return false; |
10298 | } |
10299 | |
10300 | bool |
10301 | ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred, |
10302 | const SCEV *LHS, const SCEV *RHS) { |
10303 | return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) || |
10304 | IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) || |
10305 | IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) || |
10306 | isKnownPredicateViaNoOverflow(Pred, LHS, RHS); |
10307 | } |
10308 | |
10309 | bool |
10310 | ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, |
10311 | const SCEV *LHS, const SCEV *RHS, |
10312 | const SCEV *FoundLHS, |
10313 | const SCEV *FoundRHS) { |
10314 | switch (Pred) { |
10315 | default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10315); |
10316 | case ICmpInst::ICMP_EQ: |
10317 | case ICmpInst::ICMP_NE: |
10318 | if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS)) |
10319 | return true; |
10320 | break; |
10321 | case ICmpInst::ICMP_SLT: |
10322 | case ICmpInst::ICMP_SLE: |
10323 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) && |
10324 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS)) |
10325 | return true; |
10326 | break; |
10327 | case ICmpInst::ICMP_SGT: |
10328 | case ICmpInst::ICMP_SGE: |
10329 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) && |
10330 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS)) |
10331 | return true; |
10332 | break; |
10333 | case ICmpInst::ICMP_ULT: |
10334 | case ICmpInst::ICMP_ULE: |
10335 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) && |
10336 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS)) |
10337 | return true; |
10338 | break; |
10339 | case ICmpInst::ICMP_UGT: |
10340 | case ICmpInst::ICMP_UGE: |
10341 | if (isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) && |
10342 | isKnownViaNonRecursiveReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS)) |
10343 | return true; |
10344 | break; |
10345 | } |
10346 | |
10347 | // Maybe it can be proved via operations? |
10348 | if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS)) |
10349 | return true; |
10350 | |
10351 | return false; |
10352 | } |
10353 | |
10354 | bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred, |
10355 | const SCEV *LHS, |
10356 | const SCEV *RHS, |
10357 | const SCEV *FoundLHS, |
10358 | const SCEV *FoundRHS) { |
10359 | if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS)) |
10360 | // The restriction on `FoundRHS` be lifted easily -- it exists only to |
10361 | // reduce the compile time impact of this optimization. |
10362 | return false; |
10363 | |
10364 | Optional<APInt> Addend = computeConstantDifference(LHS, FoundLHS); |
10365 | if (!Addend) |
10366 | return false; |
10367 | |
10368 | const APInt &ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt(); |
10369 | |
10370 | // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the |
10371 | // antecedent "`FoundLHS` `Pred` `FoundRHS`". |
10372 | ConstantRange FoundLHSRange = |
10373 | ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS); |
10374 | |
10375 | // Since `LHS` is `FoundLHS` + `Addend`, we can compute a range for `LHS`: |
10376 | ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(*Addend)); |
10377 | |
10378 | // We can also compute the range of values for `LHS` that satisfy the |
10379 | // consequent, "`LHS` `Pred` `RHS`": |
10380 | const APInt &ConstRHS = cast<SCEVConstant>(RHS)->getAPInt(); |
10381 | ConstantRange SatisfyingLHSRange = |
10382 | ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS); |
10383 | |
10384 | // The antecedent implies the consequent if every value of `LHS` that |
10385 | // satisfies the antecedent also satisfies the consequent. |
10386 | return SatisfyingLHSRange.contains(LHSRange); |
10387 | } |
10388 | |
10389 | bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride, |
10390 | bool IsSigned, bool NoWrap) { |
10391 | assert(isKnownPositive(Stride) && "Positive stride expected!")((isKnownPositive(Stride) && "Positive stride expected!" ) ? static_cast<void> (0) : __assert_fail ("isKnownPositive(Stride) && \"Positive stride expected!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10391, __PRETTY_FUNCTION__)); |
10392 | |
10393 | if (NoWrap) return false; |
10394 | |
10395 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); |
10396 | const SCEV *One = getOne(Stride->getType()); |
10397 | |
10398 | if (IsSigned) { |
10399 | APInt MaxRHS = getSignedRangeMax(RHS); |
10400 | APInt MaxValue = APInt::getSignedMaxValue(BitWidth); |
10401 | APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One)); |
10402 | |
10403 | // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow! |
10404 | return (std::move(MaxValue) - MaxStrideMinusOne).slt(MaxRHS); |
10405 | } |
10406 | |
10407 | APInt MaxRHS = getUnsignedRangeMax(RHS); |
10408 | APInt MaxValue = APInt::getMaxValue(BitWidth); |
10409 | APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One)); |
10410 | |
10411 | // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow! |
10412 | return (std::move(MaxValue) - MaxStrideMinusOne).ult(MaxRHS); |
10413 | } |
10414 | |
10415 | bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride, |
10416 | bool IsSigned, bool NoWrap) { |
10417 | if (NoWrap) return false; |
10418 | |
10419 | unsigned BitWidth = getTypeSizeInBits(RHS->getType()); |
10420 | const SCEV *One = getOne(Stride->getType()); |
10421 | |
10422 | if (IsSigned) { |
10423 | APInt MinRHS = getSignedRangeMin(RHS); |
10424 | APInt MinValue = APInt::getSignedMinValue(BitWidth); |
10425 | APInt MaxStrideMinusOne = getSignedRangeMax(getMinusSCEV(Stride, One)); |
10426 | |
10427 | // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow! |
10428 | return (std::move(MinValue) + MaxStrideMinusOne).sgt(MinRHS); |
10429 | } |
10430 | |
10431 | APInt MinRHS = getUnsignedRangeMin(RHS); |
10432 | APInt MinValue = APInt::getMinValue(BitWidth); |
10433 | APInt MaxStrideMinusOne = getUnsignedRangeMax(getMinusSCEV(Stride, One)); |
10434 | |
10435 | // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow! |
10436 | return (std::move(MinValue) + MaxStrideMinusOne).ugt(MinRHS); |
10437 | } |
10438 | |
10439 | const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step, |
10440 | bool Equality) { |
10441 | const SCEV *One = getOne(Step->getType()); |
10442 | Delta = Equality ? getAddExpr(Delta, Step) |
10443 | : getAddExpr(Delta, getMinusSCEV(Step, One)); |
10444 | return getUDivExpr(Delta, Step); |
10445 | } |
10446 | |
10447 | const SCEV *ScalarEvolution::computeMaxBECountForLT(const SCEV *Start, |
10448 | const SCEV *Stride, |
10449 | const SCEV *End, |
10450 | unsigned BitWidth, |
10451 | bool IsSigned) { |
10452 | |
10453 | assert(!isKnownNonPositive(Stride) &&((!isKnownNonPositive(Stride) && "Stride is expected strictly positive!" ) ? static_cast<void> (0) : __assert_fail ("!isKnownNonPositive(Stride) && \"Stride is expected strictly positive!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10454, __PRETTY_FUNCTION__)) |
10454 | "Stride is expected strictly positive!")((!isKnownNonPositive(Stride) && "Stride is expected strictly positive!" ) ? static_cast<void> (0) : __assert_fail ("!isKnownNonPositive(Stride) && \"Stride is expected strictly positive!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10454, __PRETTY_FUNCTION__)); |
10455 | // Calculate the maximum backedge count based on the range of values |
10456 | // permitted by Start, End, and Stride. |
10457 | const SCEV *MaxBECount; |
10458 | APInt MinStart = |
10459 | IsSigned ? getSignedRangeMin(Start) : getUnsignedRangeMin(Start); |
10460 | |
10461 | APInt StrideForMaxBECount = |
10462 | IsSigned ? getSignedRangeMin(Stride) : getUnsignedRangeMin(Stride); |
10463 | |
10464 | // We already know that the stride is positive, so we paper over conservatism |
10465 | // in our range computation by forcing StrideForMaxBECount to be at least one. |
10466 | // In theory this is unnecessary, but we expect MaxBECount to be a |
10467 | // SCEVConstant, and (udiv <constant> 0) is not constant folded by SCEV (there |
10468 | // is nothing to constant fold it to). |
10469 | APInt One(BitWidth, 1, IsSigned); |
10470 | StrideForMaxBECount = APIntOps::smax(One, StrideForMaxBECount); |
10471 | |
10472 | APInt MaxValue = IsSigned ? APInt::getSignedMaxValue(BitWidth) |
10473 | : APInt::getMaxValue(BitWidth); |
10474 | APInt Limit = MaxValue - (StrideForMaxBECount - 1); |
10475 | |
10476 | // Although End can be a MAX expression we estimate MaxEnd considering only |
10477 | // the case End = RHS of the loop termination condition. This is safe because |
10478 | // in the other case (End - Start) is zero, leading to a zero maximum backedge |
10479 | // taken count. |
10480 | APInt MaxEnd = IsSigned ? APIntOps::smin(getSignedRangeMax(End), Limit) |
10481 | : APIntOps::umin(getUnsignedRangeMax(End), Limit); |
10482 | |
10483 | MaxBECount = computeBECount(getConstant(MaxEnd - MinStart) /* Delta */, |
10484 | getConstant(StrideForMaxBECount) /* Step */, |
10485 | false /* Equality */); |
10486 | |
10487 | return MaxBECount; |
10488 | } |
10489 | |
10490 | ScalarEvolution::ExitLimit |
10491 | ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS, |
10492 | const Loop *L, bool IsSigned, |
10493 | bool ControlsExit, bool AllowPredicates) { |
10494 | SmallPtrSet<const SCEVPredicate *, 4> Predicates; |
10495 | |
10496 | const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS); |
10497 | bool PredicatedIV = false; |
10498 | |
10499 | if (!IV && AllowPredicates) { |
10500 | // Try to make this an AddRec using runtime tests, in the first X |
10501 | // iterations of this loop, where X is the SCEV expression found by the |
10502 | // algorithm below. |
10503 | IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates); |
10504 | PredicatedIV = true; |
10505 | } |
10506 | |
10507 | // Avoid weird loops |
10508 | if (!IV || IV->getLoop() != L || !IV->isAffine()) |
10509 | return getCouldNotCompute(); |
10510 | |
10511 | bool NoWrap = ControlsExit && |
10512 | IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW); |
10513 | |
10514 | const SCEV *Stride = IV->getStepRecurrence(*this); |
10515 | |
10516 | bool PositiveStride = isKnownPositive(Stride); |
10517 | |
10518 | // Avoid negative or zero stride values. |
10519 | if (!PositiveStride) { |
10520 | // We can compute the correct backedge taken count for loops with unknown |
10521 | // strides if we can prove that the loop is not an infinite loop with side |
10522 | // effects. Here's the loop structure we are trying to handle - |
10523 | // |
10524 | // i = start |
10525 | // do { |
10526 | // A[i] = i; |
10527 | // i += s; |
10528 | // } while (i < end); |
10529 | // |
10530 | // The backedge taken count for such loops is evaluated as - |
10531 | // (max(end, start + stride) - start - 1) /u stride |
10532 | // |
10533 | // The additional preconditions that we need to check to prove correctness |
10534 | // of the above formula is as follows - |
10535 | // |
10536 | // a) IV is either nuw or nsw depending upon signedness (indicated by the |
10537 | // NoWrap flag). |
10538 | // b) loop is single exit with no side effects. |
10539 | // |
10540 | // |
10541 | // Precondition a) implies that if the stride is negative, this is a single |
10542 | // trip loop. The backedge taken count formula reduces to zero in this case. |
10543 | // |
10544 | // Precondition b) implies that the unknown stride cannot be zero otherwise |
10545 | // we have UB. |
10546 | // |
10547 | // The positive stride case is the same as isKnownPositive(Stride) returning |
10548 | // true (original behavior of the function). |
10549 | // |
10550 | // We want to make sure that the stride is truly unknown as there are edge |
10551 | // cases where ScalarEvolution propagates no wrap flags to the |
10552 | // post-increment/decrement IV even though the increment/decrement operation |
10553 | // itself is wrapping. The computed backedge taken count may be wrong in |
10554 | // such cases. This is prevented by checking that the stride is not known to |
10555 | // be either positive or non-positive. For example, no wrap flags are |
10556 | // propagated to the post-increment IV of this loop with a trip count of 2 - |
10557 | // |
10558 | // unsigned char i; |
10559 | // for(i=127; i<128; i+=129) |
10560 | // A[i] = i; |
10561 | // |
10562 | if (PredicatedIV || !NoWrap || isKnownNonPositive(Stride) || |
10563 | !loopHasNoSideEffects(L)) |
10564 | return getCouldNotCompute(); |
10565 | } else if (!Stride->isOne() && |
10566 | doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap)) |
10567 | // Avoid proven overflow cases: this will ensure that the backedge taken |
10568 | // count will not generate any unsigned overflow. Relaxed no-overflow |
10569 | // conditions exploit NoWrapFlags, allowing to optimize in presence of |
10570 | // undefined behaviors like the case of C language. |
10571 | return getCouldNotCompute(); |
10572 | |
10573 | ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT |
10574 | : ICmpInst::ICMP_ULT; |
10575 | const SCEV *Start = IV->getStart(); |
10576 | const SCEV *End = RHS; |
10577 | // When the RHS is not invariant, we do not know the end bound of the loop and |
10578 | // cannot calculate the ExactBECount needed by ExitLimit. However, we can |
10579 | // calculate the MaxBECount, given the start, stride and max value for the end |
10580 | // bound of the loop (RHS), and the fact that IV does not overflow (which is |
10581 | // checked above). |
10582 | if (!isLoopInvariant(RHS, L)) { |
10583 | const SCEV *MaxBECount = computeMaxBECountForLT( |
10584 | Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned); |
10585 | return ExitLimit(getCouldNotCompute() /* ExactNotTaken */, MaxBECount, |
10586 | false /*MaxOrZero*/, Predicates); |
10587 | } |
10588 | // If the backedge is taken at least once, then it will be taken |
10589 | // (End-Start)/Stride times (rounded up to a multiple of Stride), where Start |
10590 | // is the LHS value of the less-than comparison the first time it is evaluated |
10591 | // and End is the RHS. |
10592 | const SCEV *BECountIfBackedgeTaken = |
10593 | computeBECount(getMinusSCEV(End, Start), Stride, false); |
10594 | // If the loop entry is guarded by the result of the backedge test of the |
10595 | // first loop iteration, then we know the backedge will be taken at least |
10596 | // once and so the backedge taken count is as above. If not then we use the |
10597 | // expression (max(End,Start)-Start)/Stride to describe the backedge count, |
10598 | // as if the backedge is taken at least once max(End,Start) is End and so the |
10599 | // result is as above, and if not max(End,Start) is Start so we get a backedge |
10600 | // count of zero. |
10601 | const SCEV *BECount; |
10602 | if (isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS)) |
10603 | BECount = BECountIfBackedgeTaken; |
10604 | else { |
10605 | End = IsSigned ? getSMaxExpr(RHS, Start) : getUMaxExpr(RHS, Start); |
10606 | BECount = computeBECount(getMinusSCEV(End, Start), Stride, false); |
10607 | } |
10608 | |
10609 | const SCEV *MaxBECount; |
10610 | bool MaxOrZero = false; |
10611 | if (isa<SCEVConstant>(BECount)) |
10612 | MaxBECount = BECount; |
10613 | else if (isa<SCEVConstant>(BECountIfBackedgeTaken)) { |
10614 | // If we know exactly how many times the backedge will be taken if it's |
10615 | // taken at least once, then the backedge count will either be that or |
10616 | // zero. |
10617 | MaxBECount = BECountIfBackedgeTaken; |
10618 | MaxOrZero = true; |
10619 | } else { |
10620 | MaxBECount = computeMaxBECountForLT( |
10621 | Start, Stride, RHS, getTypeSizeInBits(LHS->getType()), IsSigned); |
10622 | } |
10623 | |
10624 | if (isa<SCEVCouldNotCompute>(MaxBECount) && |
10625 | !isa<SCEVCouldNotCompute>(BECount)) |
10626 | MaxBECount = getConstant(getUnsignedRangeMax(BECount)); |
10627 | |
10628 | return ExitLimit(BECount, MaxBECount, MaxOrZero, Predicates); |
10629 | } |
10630 | |
10631 | ScalarEvolution::ExitLimit |
10632 | ScalarEvolution::howManyGreaterThans(const SCEV *LHS, const SCEV *RHS, |
10633 | const Loop *L, bool IsSigned, |
10634 | bool ControlsExit, bool AllowPredicates) { |
10635 | SmallPtrSet<const SCEVPredicate *, 4> Predicates; |
10636 | // We handle only IV > Invariant |
10637 | if (!isLoopInvariant(RHS, L)) |
10638 | return getCouldNotCompute(); |
10639 | |
10640 | const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS); |
10641 | if (!IV && AllowPredicates) |
10642 | // Try to make this an AddRec using runtime tests, in the first X |
10643 | // iterations of this loop, where X is the SCEV expression found by the |
10644 | // algorithm below. |
10645 | IV = convertSCEVToAddRecWithPredicates(LHS, L, Predicates); |
10646 | |
10647 | // Avoid weird loops |
10648 | if (!IV || IV->getLoop() != L || !IV->isAffine()) |
10649 | return getCouldNotCompute(); |
10650 | |
10651 | bool NoWrap = ControlsExit && |
10652 | IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW); |
10653 | |
10654 | const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this)); |
10655 | |
10656 | // Avoid negative or zero stride values |
10657 | if (!isKnownPositive(Stride)) |
10658 | return getCouldNotCompute(); |
10659 | |
10660 | // Avoid proven overflow cases: this will ensure that the backedge taken count |
10661 | // will not generate any unsigned overflow. Relaxed no-overflow conditions |
10662 | // exploit NoWrapFlags, allowing to optimize in presence of undefined |
10663 | // behaviors like the case of C language. |
10664 | if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap)) |
10665 | return getCouldNotCompute(); |
10666 | |
10667 | ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT |
10668 | : ICmpInst::ICMP_UGT; |
10669 | |
10670 | const SCEV *Start = IV->getStart(); |
10671 | const SCEV *End = RHS; |
10672 | if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) |
10673 | End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start); |
10674 | |
10675 | const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false); |
10676 | |
10677 | APInt MaxStart = IsSigned ? getSignedRangeMax(Start) |
10678 | : getUnsignedRangeMax(Start); |
10679 | |
10680 | APInt MinStride = IsSigned ? getSignedRangeMin(Stride) |
10681 | : getUnsignedRangeMin(Stride); |
10682 | |
10683 | unsigned BitWidth = getTypeSizeInBits(LHS->getType()); |
10684 | APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1) |
10685 | : APInt::getMinValue(BitWidth) + (MinStride - 1); |
10686 | |
10687 | // Although End can be a MIN expression we estimate MinEnd considering only |
10688 | // the case End = RHS. This is safe because in the other case (Start - End) |
10689 | // is zero, leading to a zero maximum backedge taken count. |
10690 | APInt MinEnd = |
10691 | IsSigned ? APIntOps::smax(getSignedRangeMin(RHS), Limit) |
10692 | : APIntOps::umax(getUnsignedRangeMin(RHS), Limit); |
10693 | |
10694 | |
10695 | const SCEV *MaxBECount = getCouldNotCompute(); |
10696 | if (isa<SCEVConstant>(BECount)) |
10697 | MaxBECount = BECount; |
10698 | else |
10699 | MaxBECount = computeBECount(getConstant(MaxStart - MinEnd), |
10700 | getConstant(MinStride), false); |
10701 | |
10702 | if (isa<SCEVCouldNotCompute>(MaxBECount)) |
10703 | MaxBECount = BECount; |
10704 | |
10705 | return ExitLimit(BECount, MaxBECount, false, Predicates); |
10706 | } |
10707 | |
10708 | const SCEV *SCEVAddRecExpr::getNumIterationsInRange(const ConstantRange &Range, |
10709 | ScalarEvolution &SE) const { |
10710 | if (Range.isFullSet()) // Infinite loop. |
10711 | return SE.getCouldNotCompute(); |
10712 | |
10713 | // If the start is a non-zero constant, shift the range to simplify things. |
10714 | if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart())) |
10715 | if (!SC->getValue()->isZero()) { |
10716 | SmallVector<const SCEV *, 4> Operands(op_begin(), op_end()); |
10717 | Operands[0] = SE.getZero(SC->getType()); |
10718 | const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(), |
10719 | getNoWrapFlags(FlagNW)); |
10720 | if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted)) |
10721 | return ShiftedAddRec->getNumIterationsInRange( |
10722 | Range.subtract(SC->getAPInt()), SE); |
10723 | // This is strange and shouldn't happen. |
10724 | return SE.getCouldNotCompute(); |
10725 | } |
10726 | |
10727 | // The only time we can solve this is when we have all constant indices. |
10728 | // Otherwise, we cannot determine the overflow conditions. |
10729 | if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); })) |
10730 | return SE.getCouldNotCompute(); |
10731 | |
10732 | // Okay at this point we know that all elements of the chrec are constants and |
10733 | // that the start element is zero. |
10734 | |
10735 | // First check to see if the range contains zero. If not, the first |
10736 | // iteration exits. |
10737 | unsigned BitWidth = SE.getTypeSizeInBits(getType()); |
10738 | if (!Range.contains(APInt(BitWidth, 0))) |
10739 | return SE.getZero(getType()); |
10740 | |
10741 | if (isAffine()) { |
10742 | // If this is an affine expression then we have this situation: |
10743 | // Solve {0,+,A} in Range === Ax in Range |
10744 | |
10745 | // We know that zero is in the range. If A is positive then we know that |
10746 | // the upper value of the range must be the first possible exit value. |
10747 | // If A is negative then the lower of the range is the last possible loop |
10748 | // value. Also note that we already checked for a full range. |
10749 | APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt(); |
10750 | APInt End = A.sge(1) ? (Range.getUpper() - 1) : Range.getLower(); |
10751 | |
10752 | // The exit value should be (End+A)/A. |
10753 | APInt ExitVal = (End + A).udiv(A); |
10754 | ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal); |
10755 | |
10756 | // Evaluate at the exit value. If we really did fall out of the valid |
10757 | // range, then we computed our trip count, otherwise wrap around or other |
10758 | // things must have happened. |
10759 | ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE); |
10760 | if (Range.contains(Val->getValue())) |
10761 | return SE.getCouldNotCompute(); // Something strange happened |
10762 | |
10763 | // Ensure that the previous value is in the range. This is a sanity check. |
10764 | assert(Range.contains(((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10767, __PRETTY_FUNCTION__)) |
10765 | EvaluateConstantChrecAtConstant(this,((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10767, __PRETTY_FUNCTION__)) |
10766 | ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) &&((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10767, __PRETTY_FUNCTION__)) |
10767 | "Linear scev computation is off in a bad way!")((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt ::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && "Linear scev computation is off in a bad way!") ? static_cast <void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - 1), SE)->getValue()) && \"Linear scev computation is off in a bad way!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10767, __PRETTY_FUNCTION__)); |
10768 | return SE.getConstant(ExitValue); |
10769 | } |
10770 | |
10771 | if (isQuadratic()) { |
10772 | if (auto S = SolveQuadraticAddRecRange(this, Range, SE)) |
10773 | return SE.getConstant(S.getValue()); |
10774 | } |
10775 | |
10776 | return SE.getCouldNotCompute(); |
10777 | } |
10778 | |
10779 | const SCEVAddRecExpr * |
10780 | SCEVAddRecExpr::getPostIncExpr(ScalarEvolution &SE) const { |
10781 | assert(getNumOperands() > 1 && "AddRec with zero step?")((getNumOperands() > 1 && "AddRec with zero step?" ) ? static_cast<void> (0) : __assert_fail ("getNumOperands() > 1 && \"AddRec with zero step?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10781, __PRETTY_FUNCTION__)); |
10782 | // There is a temptation to just call getAddExpr(this, getStepRecurrence(SE)), |
10783 | // but in this case we cannot guarantee that the value returned will be an |
10784 | // AddRec because SCEV does not have a fixed point where it stops |
10785 | // simplification: it is legal to return ({rec1} + {rec2}). For example, it |
10786 | // may happen if we reach arithmetic depth limit while simplifying. So we |
10787 | // construct the returned value explicitly. |
10788 | SmallVector<const SCEV *, 3> Ops; |
10789 | // If this is {A,+,B,+,C,...,+,N}, then its step is {B,+,C,+,...,+,N}, and |
10790 | // (this + Step) is {A+B,+,B+C,+...,+,N}. |
10791 | for (unsigned i = 0, e = getNumOperands() - 1; i < e; ++i) |
10792 | Ops.push_back(SE.getAddExpr(getOperand(i), getOperand(i + 1))); |
10793 | // We know that the last operand is not a constant zero (otherwise it would |
10794 | // have been popped out earlier). This guarantees us that if the result has |
10795 | // the same last operand, then it will also not be popped out, meaning that |
10796 | // the returned value will be an AddRec. |
10797 | const SCEV *Last = getOperand(getNumOperands() - 1); |
10798 | assert(!Last->isZero() && "Recurrency with zero step?")((!Last->isZero() && "Recurrency with zero step?") ? static_cast<void> (0) : __assert_fail ("!Last->isZero() && \"Recurrency with zero step?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 10798, __PRETTY_FUNCTION__)); |
10799 | Ops.push_back(Last); |
10800 | return cast<SCEVAddRecExpr>(SE.getAddRecExpr(Ops, getLoop(), |
10801 | SCEV::FlagAnyWrap)); |
10802 | } |
10803 | |
10804 | // Return true when S contains at least an undef value. |
10805 | static inline bool containsUndefs(const SCEV *S) { |
10806 | return SCEVExprContains(S, [](const SCEV *S) { |
10807 | if (const auto *SU = dyn_cast<SCEVUnknown>(S)) |
10808 | return isa<UndefValue>(SU->getValue()); |
10809 | else if (const auto *SC = dyn_cast<SCEVConstant>(S)) |
10810 | return isa<UndefValue>(SC->getValue()); |
10811 | return false; |
10812 | }); |
10813 | } |
10814 | |
10815 | namespace { |
10816 | |
10817 | // Collect all steps of SCEV expressions. |
10818 | struct SCEVCollectStrides { |
10819 | ScalarEvolution &SE; |
10820 | SmallVectorImpl<const SCEV *> &Strides; |
10821 | |
10822 | SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S) |
10823 | : SE(SE), Strides(S) {} |
10824 | |
10825 | bool follow(const SCEV *S) { |
10826 | if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) |
10827 | Strides.push_back(AR->getStepRecurrence(SE)); |
10828 | return true; |
10829 | } |
10830 | |
10831 | bool isDone() const { return false; } |
10832 | }; |
10833 | |
10834 | // Collect all SCEVUnknown and SCEVMulExpr expressions. |
10835 | struct SCEVCollectTerms { |
10836 | SmallVectorImpl<const SCEV *> &Terms; |
10837 | |
10838 | SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T) : Terms(T) {} |
10839 | |
10840 | bool follow(const SCEV *S) { |
10841 | if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S) || |
10842 | isa<SCEVSignExtendExpr>(S)) { |
10843 | if (!containsUndefs(S)) |
10844 | Terms.push_back(S); |
10845 | |
10846 | // Stop recursion: once we collected a term, do not walk its operands. |
10847 | return false; |
10848 | } |
10849 | |
10850 | // Keep looking. |
10851 | return true; |
10852 | } |
10853 | |
10854 | bool isDone() const { return false; } |
10855 | }; |
10856 | |
10857 | // Check if a SCEV contains an AddRecExpr. |
10858 | struct SCEVHasAddRec { |
10859 | bool &ContainsAddRec; |
10860 | |
10861 | SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) { |
10862 | ContainsAddRec = false; |
10863 | } |
10864 | |
10865 | bool follow(const SCEV *S) { |
10866 | if (isa<SCEVAddRecExpr>(S)) { |
10867 | ContainsAddRec = true; |
10868 | |
10869 | // Stop recursion: once we collected a term, do not walk its operands. |
10870 | return false; |
10871 | } |
10872 | |
10873 | // Keep looking. |
10874 | return true; |
10875 | } |
10876 | |
10877 | bool isDone() const { return false; } |
10878 | }; |
10879 | |
10880 | // Find factors that are multiplied with an expression that (possibly as a |
10881 | // subexpression) contains an AddRecExpr. In the expression: |
10882 | // |
10883 | // 8 * (100 + %p * %q * (%a + {0, +, 1}_loop)) |
10884 | // |
10885 | // "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)" |
10886 | // that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size |
10887 | // parameters as they form a product with an induction variable. |
10888 | // |
10889 | // This collector expects all array size parameters to be in the same MulExpr. |
10890 | // It might be necessary to later add support for collecting parameters that are |
10891 | // spread over different nested MulExpr. |
10892 | struct SCEVCollectAddRecMultiplies { |
10893 | SmallVectorImpl<const SCEV *> &Terms; |
10894 | ScalarEvolution &SE; |
10895 | |
10896 | SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE) |
10897 | : Terms(T), SE(SE) {} |
10898 | |
10899 | bool follow(const SCEV *S) { |
10900 | if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) { |
10901 | bool HasAddRec = false; |
10902 | SmallVector<const SCEV *, 0> Operands; |
10903 | for (auto Op : Mul->operands()) { |
10904 | const SCEVUnknown *Unknown = dyn_cast<SCEVUnknown>(Op); |
10905 | if (Unknown && !isa<CallInst>(Unknown->getValue())) { |
10906 | Operands.push_back(Op); |
10907 | } else if (Unknown) { |
10908 | HasAddRec = true; |
10909 | } else { |
10910 | bool ContainsAddRec; |
10911 | SCEVHasAddRec ContiansAddRec(ContainsAddRec); |
10912 | visitAll(Op, ContiansAddRec); |
10913 | HasAddRec |= ContainsAddRec; |
10914 | } |
10915 | } |
10916 | if (Operands.size() == 0) |
10917 | return true; |
10918 | |
10919 | if (!HasAddRec) |
10920 | return false; |
10921 | |
10922 | Terms.push_back(SE.getMulExpr(Operands)); |
10923 | // Stop recursion: once we collected a term, do not walk its operands. |
10924 | return false; |
10925 | } |
10926 | |
10927 | // Keep looking. |
10928 | return true; |
10929 | } |
10930 | |
10931 | bool isDone() const { return false; } |
10932 | }; |
10933 | |
10934 | } // end anonymous namespace |
10935 | |
10936 | /// Find parametric terms in this SCEVAddRecExpr. We first for parameters in |
10937 | /// two places: |
10938 | /// 1) The strides of AddRec expressions. |
10939 | /// 2) Unknowns that are multiplied with AddRec expressions. |
10940 | void ScalarEvolution::collectParametricTerms(const SCEV *Expr, |
10941 | SmallVectorImpl<const SCEV *> &Terms) { |
10942 | SmallVector<const SCEV *, 4> Strides; |
10943 | SCEVCollectStrides StrideCollector(*this, Strides); |
10944 | visitAll(Expr, StrideCollector); |
10945 | |
10946 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) |
10947 | dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) |
10948 | for (const SCEV *S : Strides)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) |
10949 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false) |
10950 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Strides:\n"; for ( const SCEV *S : Strides) dbgs() << *S << "\n"; }; } } while (false); |
10951 | |
10952 | for (const SCEV *S : Strides) { |
10953 | SCEVCollectTerms TermCollector(Terms); |
10954 | visitAll(S, TermCollector); |
10955 | } |
10956 | |
10957 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
10958 | dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
10959 | for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
10960 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
10961 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false); |
10962 | |
10963 | SCEVCollectAddRecMultiplies MulCollector(Terms, *this); |
10964 | visitAll(Expr, MulCollector); |
10965 | } |
10966 | |
10967 | static bool findArrayDimensionsRec(ScalarEvolution &SE, |
10968 | SmallVectorImpl<const SCEV *> &Terms, |
10969 | SmallVectorImpl<const SCEV *> &Sizes) { |
10970 | int Last = Terms.size() - 1; |
10971 | const SCEV *Step = Terms[Last]; |
10972 | |
10973 | // End of recursion. |
10974 | if (Last == 0) { |
10975 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) { |
10976 | SmallVector<const SCEV *, 2> Qs; |
10977 | for (const SCEV *Op : M->operands()) |
10978 | if (!isa<SCEVConstant>(Op)) |
10979 | Qs.push_back(Op); |
10980 | |
10981 | Step = SE.getMulExpr(Qs); |
10982 | } |
10983 | |
10984 | Sizes.push_back(Step); |
10985 | return true; |
10986 | } |
10987 | |
10988 | for (const SCEV *&Term : Terms) { |
10989 | // Normalize the terms before the next call to findArrayDimensionsRec. |
10990 | const SCEV *Q, *R; |
10991 | SCEVDivision::divide(SE, Term, Step, &Q, &R); |
10992 | |
10993 | // Bail out when GCD does not evenly divide one of the terms. |
10994 | if (!R->isZero()) |
10995 | return false; |
10996 | |
10997 | Term = Q; |
10998 | } |
10999 | |
11000 | // Remove all SCEVConstants. |
11001 | Terms.erase( |
11002 | remove_if(Terms, [](const SCEV *E) { return isa<SCEVConstant>(E); }), |
11003 | Terms.end()); |
11004 | |
11005 | if (Terms.size() > 0) |
11006 | if (!findArrayDimensionsRec(SE, Terms, Sizes)) |
11007 | return false; |
11008 | |
11009 | Sizes.push_back(Step); |
11010 | return true; |
11011 | } |
11012 | |
11013 | // Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter. |
11014 | static inline bool containsParameters(SmallVectorImpl<const SCEV *> &Terms) { |
11015 | for (const SCEV *T : Terms) |
11016 | if (SCEVExprContains(T, isa<SCEVUnknown, const SCEV *>)) |
11017 | return true; |
11018 | return false; |
11019 | } |
11020 | |
11021 | // Return the number of product terms in S. |
11022 | static inline int numberOfTerms(const SCEV *S) { |
11023 | if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S)) |
11024 | return Expr->getNumOperands(); |
11025 | return 1; |
11026 | } |
11027 | |
11028 | static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) { |
11029 | if (isa<SCEVConstant>(T)) |
11030 | return nullptr; |
11031 | |
11032 | if (isa<SCEVUnknown>(T)) |
11033 | return T; |
11034 | |
11035 | if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) { |
11036 | SmallVector<const SCEV *, 2> Factors; |
11037 | for (const SCEV *Op : M->operands()) |
11038 | if (!isa<SCEVConstant>(Op)) |
11039 | Factors.push_back(Op); |
11040 | |
11041 | return SE.getMulExpr(Factors); |
11042 | } |
11043 | |
11044 | return T; |
11045 | } |
11046 | |
11047 | /// Return the size of an element read or written by Inst. |
11048 | const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) { |
11049 | Type *Ty; |
11050 | if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) |
11051 | Ty = Store->getValueOperand()->getType(); |
11052 | else if (LoadInst *Load = dyn_cast<LoadInst>(Inst)) |
11053 | Ty = Load->getType(); |
11054 | else |
11055 | return nullptr; |
11056 | |
11057 | Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty)); |
11058 | return getSizeOfExpr(ETy, Ty); |
11059 | } |
11060 | |
11061 | void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms, |
11062 | SmallVectorImpl<const SCEV *> &Sizes, |
11063 | const SCEV *ElementSize) { |
11064 | if (Terms.size() < 1 || !ElementSize) |
11065 | return; |
11066 | |
11067 | // Early return when Terms do not contain parameters: we do not delinearize |
11068 | // non parametric SCEVs. |
11069 | if (!containsParameters(Terms)) |
11070 | return; |
11071 | |
11072 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
11073 | dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
11074 | for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
11075 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false) |
11076 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while (false); |
11077 | |
11078 | // Remove duplicates. |
11079 | array_pod_sort(Terms.begin(), Terms.end()); |
11080 | Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end()); |
11081 | |
11082 | // Put larger terms first. |
11083 | llvm::sort(Terms, [](const SCEV *LHS, const SCEV *RHS) { |
11084 | return numberOfTerms(LHS) > numberOfTerms(RHS); |
11085 | }); |
11086 | |
11087 | // Try to divide all terms by the element size. If term is not divisible by |
11088 | // element size, proceed with the original term. |
11089 | for (const SCEV *&Term : Terms) { |
11090 | const SCEV *Q, *R; |
11091 | SCEVDivision::divide(*this, Term, ElementSize, &Q, &R); |
11092 | if (!Q->isZero()) |
11093 | Term = Q; |
11094 | } |
11095 | |
11096 | SmallVector<const SCEV *, 4> NewTerms; |
11097 | |
11098 | // Remove constant factors. |
11099 | for (const SCEV *T : Terms) |
11100 | if (const SCEV *NewT = removeConstantFactors(*this, T)) |
11101 | NewTerms.push_back(NewT); |
11102 | |
11103 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) |
11104 | dbgs() << "Terms after sorting:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) |
11105 | for (const SCEV *T : NewTerms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) |
11106 | dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false) |
11107 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Terms after sorting:\n" ; for (const SCEV *T : NewTerms) dbgs() << *T << "\n" ; }; } } while (false); |
11108 | |
11109 | if (NewTerms.empty() || !findArrayDimensionsRec(*this, NewTerms, Sizes)) { |
11110 | Sizes.clear(); |
11111 | return; |
11112 | } |
11113 | |
11114 | // The last element to be pushed into Sizes is the size of an element. |
11115 | Sizes.push_back(ElementSize); |
11116 | |
11117 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) |
11118 | dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) |
11119 | for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) |
11120 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false) |
11121 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while (false); |
11122 | } |
11123 | |
11124 | void ScalarEvolution::computeAccessFunctions( |
11125 | const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts, |
11126 | SmallVectorImpl<const SCEV *> &Sizes) { |
11127 | // Early exit in case this SCEV is not an affine multivariate function. |
11128 | if (Sizes.empty()) |
11129 | return; |
11130 | |
11131 | if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr)) |
11132 | if (!AR->isAffine()) |
11133 | return; |
11134 | |
11135 | const SCEV *Res = Expr; |
11136 | int Last = Sizes.size() - 1; |
11137 | for (int i = Last; i >= 0; i--) { |
11138 | const SCEV *Q, *R; |
11139 | SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R); |
11140 | |
11141 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) |
11142 | dbgs() << "Res: " << *Res << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) |
11143 | dbgs() << "Sizes[i]: " << *Sizes[i] << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) |
11144 | dbgs() << "Res divided by Sizes[i]:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) |
11145 | dbgs() << "Quotient: " << *Q << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) |
11146 | dbgs() << "Remainder: " << *R << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false) |
11147 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Res: " << *Res << "\n"; dbgs() << "Sizes[i]: " << *Sizes[ i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n" ; dbgs() << "Quotient: " << *Q << "\n"; dbgs () << "Remainder: " << *R << "\n"; }; } } while (false); |
11148 | |
11149 | Res = Q; |
11150 | |
11151 | // Do not record the last subscript corresponding to the size of elements in |
11152 | // the array. |
11153 | if (i == Last) { |
11154 | |
11155 | // Bail out if the remainder is too complex. |
11156 | if (isa<SCEVAddRecExpr>(R)) { |
11157 | Subscripts.clear(); |
11158 | Sizes.clear(); |
11159 | return; |
11160 | } |
11161 | |
11162 | continue; |
11163 | } |
11164 | |
11165 | // Record the access function for the current subscript. |
11166 | Subscripts.push_back(R); |
11167 | } |
11168 | |
11169 | // Also push in last position the remainder of the last division: it will be |
11170 | // the access function of the innermost dimension. |
11171 | Subscripts.push_back(Res); |
11172 | |
11173 | std::reverse(Subscripts.begin(), Subscripts.end()); |
11174 | |
11175 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) |
11176 | dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) |
11177 | for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) |
11178 | dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false) |
11179 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for (const SCEV *S : Subscripts) dbgs() << *S << "\n" ; }; } } while (false); |
11180 | } |
11181 | |
11182 | /// Splits the SCEV into two vectors of SCEVs representing the subscripts and |
11183 | /// sizes of an array access. Returns the remainder of the delinearization that |
11184 | /// is the offset start of the array. The SCEV->delinearize algorithm computes |
11185 | /// the multiples of SCEV coefficients: that is a pattern matching of sub |
11186 | /// expressions in the stride and base of a SCEV corresponding to the |
11187 | /// computation of a GCD (greatest common divisor) of base and stride. When |
11188 | /// SCEV->delinearize fails, it returns the SCEV unchanged. |
11189 | /// |
11190 | /// For example: when analyzing the memory access A[i][j][k] in this loop nest |
11191 | /// |
11192 | /// void foo(long n, long m, long o, double A[n][m][o]) { |
11193 | /// |
11194 | /// for (long i = 0; i < n; i++) |
11195 | /// for (long j = 0; j < m; j++) |
11196 | /// for (long k = 0; k < o; k++) |
11197 | /// A[i][j][k] = 1.0; |
11198 | /// } |
11199 | /// |
11200 | /// the delinearization input is the following AddRec SCEV: |
11201 | /// |
11202 | /// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k> |
11203 | /// |
11204 | /// From this SCEV, we are able to say that the base offset of the access is %A |
11205 | /// because it appears as an offset that does not divide any of the strides in |
11206 | /// the loops: |
11207 | /// |
11208 | /// CHECK: Base offset: %A |
11209 | /// |
11210 | /// and then SCEV->delinearize determines the size of some of the dimensions of |
11211 | /// the array as these are the multiples by which the strides are happening: |
11212 | /// |
11213 | /// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes. |
11214 | /// |
11215 | /// Note that the outermost dimension remains of UnknownSize because there are |
11216 | /// no strides that would help identifying the size of the last dimension: when |
11217 | /// the array has been statically allocated, one could compute the size of that |
11218 | /// dimension by dividing the overall size of the array by the size of the known |
11219 | /// dimensions: %m * %o * 8. |
11220 | /// |
11221 | /// Finally delinearize provides the access functions for the array reference |
11222 | /// that does correspond to A[i][j][k] of the above C testcase: |
11223 | /// |
11224 | /// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>] |
11225 | /// |
11226 | /// The testcases are checking the output of a function pass: |
11227 | /// DelinearizationPass that walks through all loads and stores of a function |
11228 | /// asking for the SCEV of the memory access with respect to all enclosing |
11229 | /// loops, calling SCEV->delinearize on that and printing the results. |
11230 | void ScalarEvolution::delinearize(const SCEV *Expr, |
11231 | SmallVectorImpl<const SCEV *> &Subscripts, |
11232 | SmallVectorImpl<const SCEV *> &Sizes, |
11233 | const SCEV *ElementSize) { |
11234 | // First step: collect parametric terms. |
11235 | SmallVector<const SCEV *, 4> Terms; |
11236 | collectParametricTerms(Expr, Terms); |
11237 | |
11238 | if (Terms.empty()) |
11239 | return; |
11240 | |
11241 | // Second step: find subscript sizes. |
11242 | findArrayDimensions(Terms, Sizes, ElementSize); |
11243 | |
11244 | if (Sizes.empty()) |
11245 | return; |
11246 | |
11247 | // Third step: compute the access functions for each subscript. |
11248 | computeAccessFunctions(Expr, Subscripts, Sizes); |
11249 | |
11250 | if (Subscripts.empty()) |
11251 | return; |
11252 | |
11253 | LLVM_DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11254 | dbgs() << "succeeded to delinearize " << *Expr << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11255 | dbgs() << "ArrayDecl[UnknownSize]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11256 | for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11257 | dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11258 | |
11259 | dbgs() << "\nArrayRef";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11260 | for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11261 | dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11262 | dbgs() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false) |
11263 | })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("scalar-evolution")) { { dbgs() << "succeeded to delinearize " << *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]" ; for (const SCEV *S : Sizes) dbgs() << "[" << *S << "]"; dbgs() << "\nArrayRef"; for (const SCEV * S : Subscripts) dbgs() << "[" << *S << "]"; dbgs() << "\n"; }; } } while (false); |
11264 | } |
11265 | |
11266 | //===----------------------------------------------------------------------===// |
11267 | // SCEVCallbackVH Class Implementation |
11268 | //===----------------------------------------------------------------------===// |
11269 | |
11270 | void ScalarEvolution::SCEVCallbackVH::deleted() { |
11271 | assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!" ) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11271, __PRETTY_FUNCTION__)); |
11272 | if (PHINode *PN = dyn_cast<PHINode>(getValPtr())) |
11273 | SE->ConstantEvolutionLoopExitValue.erase(PN); |
11274 | SE->eraseValueFromMap(getValPtr()); |
11275 | // this now dangles! |
11276 | } |
11277 | |
11278 | void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) { |
11279 | assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!" ) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11279, __PRETTY_FUNCTION__)); |
11280 | |
11281 | // Forget all the expressions associated with users of the old value, |
11282 | // so that future queries will recompute the expressions using the new |
11283 | // value. |
11284 | Value *Old = getValPtr(); |
11285 | SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end()); |
11286 | SmallPtrSet<User *, 8> Visited; |
11287 | while (!Worklist.empty()) { |
11288 | User *U = Worklist.pop_back_val(); |
11289 | // Deleting the Old value will cause this to dangle. Postpone |
11290 | // that until everything else is done. |
11291 | if (U == Old) |
11292 | continue; |
11293 | if (!Visited.insert(U).second) |
11294 | continue; |
11295 | if (PHINode *PN = dyn_cast<PHINode>(U)) |
11296 | SE->ConstantEvolutionLoopExitValue.erase(PN); |
11297 | SE->eraseValueFromMap(U); |
11298 | Worklist.insert(Worklist.end(), U->user_begin(), U->user_end()); |
11299 | } |
11300 | // Delete the Old value. |
11301 | if (PHINode *PN = dyn_cast<PHINode>(Old)) |
11302 | SE->ConstantEvolutionLoopExitValue.erase(PN); |
11303 | SE->eraseValueFromMap(Old); |
11304 | // this now dangles! |
11305 | } |
11306 | |
11307 | ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se) |
11308 | : CallbackVH(V), SE(se) {} |
11309 | |
11310 | //===----------------------------------------------------------------------===// |
11311 | // ScalarEvolution Class Implementation |
11312 | //===----------------------------------------------------------------------===// |
11313 | |
11314 | ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI, |
11315 | AssumptionCache &AC, DominatorTree &DT, |
11316 | LoopInfo &LI) |
11317 | : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI), |
11318 | CouldNotCompute(new SCEVCouldNotCompute()), ValuesAtScopes(64), |
11319 | LoopDispositions(64), BlockDispositions(64) { |
11320 | // To use guards for proving predicates, we need to scan every instruction in |
11321 | // relevant basic blocks, and not just terminators. Doing this is a waste of |
11322 | // time if the IR does not actually contain any calls to |
11323 | // @llvm.experimental.guard, so do a quick check and remember this beforehand. |
11324 | // |
11325 | // This pessimizes the case where a pass that preserves ScalarEvolution wants |
11326 | // to _add_ guards to the module when there weren't any before, and wants |
11327 | // ScalarEvolution to optimize based on those guards. For now we prefer to be |
11328 | // efficient in lieu of being smart in that rather obscure case. |
11329 | |
11330 | auto *GuardDecl = F.getParent()->getFunction( |
11331 | Intrinsic::getName(Intrinsic::experimental_guard)); |
11332 | HasGuards = GuardDecl && !GuardDecl->use_empty(); |
11333 | } |
11334 | |
11335 | ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg) |
11336 | : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT), |
11337 | LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)), |
11338 | ValueExprMap(std::move(Arg.ValueExprMap)), |
11339 | PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)), |
11340 | PendingPhiRanges(std::move(Arg.PendingPhiRanges)), |
11341 | PendingMerges(std::move(Arg.PendingMerges)), |
11342 | MinTrailingZerosCache(std::move(Arg.MinTrailingZerosCache)), |
11343 | BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)), |
11344 | PredicatedBackedgeTakenCounts( |
11345 | std::move(Arg.PredicatedBackedgeTakenCounts)), |
11346 | ConstantEvolutionLoopExitValue( |
11347 | std::move(Arg.ConstantEvolutionLoopExitValue)), |
11348 | ValuesAtScopes(std::move(Arg.ValuesAtScopes)), |
11349 | LoopDispositions(std::move(Arg.LoopDispositions)), |
11350 | LoopPropertiesCache(std::move(Arg.LoopPropertiesCache)), |
11351 | BlockDispositions(std::move(Arg.BlockDispositions)), |
11352 | UnsignedRanges(std::move(Arg.UnsignedRanges)), |
11353 | SignedRanges(std::move(Arg.SignedRanges)), |
11354 | UniqueSCEVs(std::move(Arg.UniqueSCEVs)), |
11355 | UniquePreds(std::move(Arg.UniquePreds)), |
11356 | SCEVAllocator(std::move(Arg.SCEVAllocator)), |
11357 | LoopUsers(std::move(Arg.LoopUsers)), |
11358 | PredicatedSCEVRewrites(std::move(Arg.PredicatedSCEVRewrites)), |
11359 | FirstUnknown(Arg.FirstUnknown) { |
11360 | Arg.FirstUnknown = nullptr; |
11361 | } |
11362 | |
11363 | ScalarEvolution::~ScalarEvolution() { |
11364 | // Iterate through all the SCEVUnknown instances and call their |
11365 | // destructors, so that they release their references to their values. |
11366 | for (SCEVUnknown *U = FirstUnknown; U;) { |
11367 | SCEVUnknown *Tmp = U; |
11368 | U = U->Next; |
11369 | Tmp->~SCEVUnknown(); |
11370 | } |
11371 | FirstUnknown = nullptr; |
11372 | |
11373 | ExprValueMap.clear(); |
11374 | ValueExprMap.clear(); |
11375 | HasRecMap.clear(); |
11376 | |
11377 | // Free any extra memory created for ExitNotTakenInfo in the unlikely event |
11378 | // that a loop had multiple computable exits. |
11379 | for (auto &BTCI : BackedgeTakenCounts) |
11380 | BTCI.second.clear(); |
11381 | for (auto &BTCI : PredicatedBackedgeTakenCounts) |
11382 | BTCI.second.clear(); |
11383 | |
11384 | assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage" ) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11384, __PRETTY_FUNCTION__)); |
11385 | assert(PendingPhiRanges.empty() && "getRangeRef garbage")((PendingPhiRanges.empty() && "getRangeRef garbage") ? static_cast<void> (0) : __assert_fail ("PendingPhiRanges.empty() && \"getRangeRef garbage\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11385, __PRETTY_FUNCTION__)); |
11386 | assert(PendingMerges.empty() && "isImpliedViaMerge garbage")((PendingMerges.empty() && "isImpliedViaMerge garbage" ) ? static_cast<void> (0) : __assert_fail ("PendingMerges.empty() && \"isImpliedViaMerge garbage\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11386, __PRETTY_FUNCTION__)); |
11387 | assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!" ) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11387, __PRETTY_FUNCTION__)); |
11388 | assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!" ) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11388, __PRETTY_FUNCTION__)); |
11389 | } |
11390 | |
11391 | bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) { |
11392 | return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L)); |
11393 | } |
11394 | |
11395 | static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE, |
11396 | const Loop *L) { |
11397 | // Print all inner loops first |
11398 | for (Loop *I : *L) |
11399 | PrintLoopInfo(OS, SE, I); |
11400 | |
11401 | OS << "Loop "; |
11402 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
11403 | OS << ": "; |
11404 | |
11405 | SmallVector<BasicBlock *, 8> ExitBlocks; |
11406 | L->getExitBlocks(ExitBlocks); |
11407 | if (ExitBlocks.size() != 1) |
11408 | OS << "<multiple exits> "; |
11409 | |
11410 | if (SE->hasLoopInvariantBackedgeTakenCount(L)) { |
11411 | OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L); |
11412 | } else { |
11413 | OS << "Unpredictable backedge-taken count. "; |
11414 | } |
11415 | |
11416 | OS << "\n" |
11417 | "Loop "; |
11418 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
11419 | OS << ": "; |
11420 | |
11421 | if (!isa<SCEVCouldNotCompute>(SE->getMaxBackedgeTakenCount(L))) { |
11422 | OS << "max backedge-taken count is " << *SE->getMaxBackedgeTakenCount(L); |
11423 | if (SE->isBackedgeTakenCountMaxOrZero(L)) |
11424 | OS << ", actual taken count either this or zero."; |
11425 | } else { |
11426 | OS << "Unpredictable max backedge-taken count. "; |
11427 | } |
11428 | |
11429 | OS << "\n" |
11430 | "Loop "; |
11431 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
11432 | OS << ": "; |
11433 | |
11434 | SCEVUnionPredicate Pred; |
11435 | auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred); |
11436 | if (!isa<SCEVCouldNotCompute>(PBT)) { |
11437 | OS << "Predicated backedge-taken count is " << *PBT << "\n"; |
11438 | OS << " Predicates:\n"; |
11439 | Pred.print(OS, 4); |
11440 | } else { |
11441 | OS << "Unpredictable predicated backedge-taken count. "; |
11442 | } |
11443 | OS << "\n"; |
11444 | |
11445 | if (SE->hasLoopInvariantBackedgeTakenCount(L)) { |
11446 | OS << "Loop "; |
11447 | L->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
11448 | OS << ": "; |
11449 | OS << "Trip multiple is " << SE->getSmallConstantTripMultiple(L) << "\n"; |
11450 | } |
11451 | } |
11452 | |
11453 | static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) { |
11454 | switch (LD) { |
11455 | case ScalarEvolution::LoopVariant: |
11456 | return "Variant"; |
11457 | case ScalarEvolution::LoopInvariant: |
11458 | return "Invariant"; |
11459 | case ScalarEvolution::LoopComputable: |
11460 | return "Computable"; |
11461 | } |
11462 | llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11462); |
11463 | } |
11464 | |
11465 | void ScalarEvolution::print(raw_ostream &OS) const { |
11466 | // ScalarEvolution's implementation of the print method is to print |
11467 | // out SCEV values of all instructions that are interesting. Doing |
11468 | // this potentially causes it to create new SCEV objects though, |
11469 | // which technically conflicts with the const qualifier. This isn't |
11470 | // observable from outside the class though, so casting away the |
11471 | // const isn't dangerous. |
11472 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); |
11473 | |
11474 | OS << "Classifying expressions for: "; |
11475 | F.printAsOperand(OS, /*PrintType=*/false); |
11476 | OS << "\n"; |
11477 | for (Instruction &I : instructions(F)) |
11478 | if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) { |
11479 | OS << I << '\n'; |
11480 | OS << " --> "; |
11481 | const SCEV *SV = SE.getSCEV(&I); |
11482 | SV->print(OS); |
11483 | if (!isa<SCEVCouldNotCompute>(SV)) { |
11484 | OS << " U: "; |
11485 | SE.getUnsignedRange(SV).print(OS); |
11486 | OS << " S: "; |
11487 | SE.getSignedRange(SV).print(OS); |
11488 | } |
11489 | |
11490 | const Loop *L = LI.getLoopFor(I.getParent()); |
11491 | |
11492 | const SCEV *AtUse = SE.getSCEVAtScope(SV, L); |
11493 | if (AtUse != SV) { |
11494 | OS << " --> "; |
11495 | AtUse->print(OS); |
11496 | if (!isa<SCEVCouldNotCompute>(AtUse)) { |
11497 | OS << " U: "; |
11498 | SE.getUnsignedRange(AtUse).print(OS); |
11499 | OS << " S: "; |
11500 | SE.getSignedRange(AtUse).print(OS); |
11501 | } |
11502 | } |
11503 | |
11504 | if (L) { |
11505 | OS << "\t\t" "Exits: "; |
11506 | const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop()); |
11507 | if (!SE.isLoopInvariant(ExitValue, L)) { |
11508 | OS << "<<Unknown>>"; |
11509 | } else { |
11510 | OS << *ExitValue; |
11511 | } |
11512 | |
11513 | bool First = true; |
11514 | for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) { |
11515 | if (First) { |
11516 | OS << "\t\t" "LoopDispositions: { "; |
11517 | First = false; |
11518 | } else { |
11519 | OS << ", "; |
11520 | } |
11521 | |
11522 | Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
11523 | OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter)); |
11524 | } |
11525 | |
11526 | for (auto *InnerL : depth_first(L)) { |
11527 | if (InnerL == L) |
11528 | continue; |
11529 | if (First) { |
11530 | OS << "\t\t" "LoopDispositions: { "; |
11531 | First = false; |
11532 | } else { |
11533 | OS << ", "; |
11534 | } |
11535 | |
11536 | InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false); |
11537 | OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL)); |
11538 | } |
11539 | |
11540 | OS << " }"; |
11541 | } |
11542 | |
11543 | OS << "\n"; |
11544 | } |
11545 | |
11546 | OS << "Determining loop execution counts for: "; |
11547 | F.printAsOperand(OS, /*PrintType=*/false); |
11548 | OS << "\n"; |
11549 | for (Loop *I : LI) |
11550 | PrintLoopInfo(OS, &SE, I); |
11551 | } |
11552 | |
11553 | ScalarEvolution::LoopDisposition |
11554 | ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) { |
11555 | auto &Values = LoopDispositions[S]; |
11556 | for (auto &V : Values) { |
11557 | if (V.getPointer() == L) |
11558 | return V.getInt(); |
11559 | } |
11560 | Values.emplace_back(L, LoopVariant); |
11561 | LoopDisposition D = computeLoopDisposition(S, L); |
11562 | auto &Values2 = LoopDispositions[S]; |
11563 | for (auto &V : make_range(Values2.rbegin(), Values2.rend())) { |
11564 | if (V.getPointer() == L) { |
11565 | V.setInt(D); |
11566 | break; |
11567 | } |
11568 | } |
11569 | return D; |
11570 | } |
11571 | |
11572 | ScalarEvolution::LoopDisposition |
11573 | ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) { |
11574 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { |
11575 | case scConstant: |
11576 | return LoopInvariant; |
11577 | case scTruncate: |
11578 | case scZeroExtend: |
11579 | case scSignExtend: |
11580 | return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L); |
11581 | case scAddRecExpr: { |
11582 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); |
11583 | |
11584 | // If L is the addrec's loop, it's computable. |
11585 | if (AR->getLoop() == L) |
11586 | return LoopComputable; |
11587 | |
11588 | // Add recurrences are never invariant in the function-body (null loop). |
11589 | if (!L) |
11590 | return LoopVariant; |
11591 | |
11592 | // Everything that is not defined at loop entry is variant. |
11593 | if (DT.dominates(L->getHeader(), AR->getLoop()->getHeader())) |
11594 | return LoopVariant; |
11595 | assert(!L->contains(AR->getLoop()) && "Containing loop's header does not"((!L->contains(AR->getLoop()) && "Containing loop's header does not" " dominate the contained loop's header?") ? static_cast<void > (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11596, __PRETTY_FUNCTION__)) |
11596 | " dominate the contained loop's header?")((!L->contains(AR->getLoop()) && "Containing loop's header does not" " dominate the contained loop's header?") ? static_cast<void > (0) : __assert_fail ("!L->contains(AR->getLoop()) && \"Containing loop's header does not\" \" dominate the contained loop's header?\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11596, __PRETTY_FUNCTION__)); |
11597 | |
11598 | // This recurrence is invariant w.r.t. L if AR's loop contains L. |
11599 | if (AR->getLoop()->contains(L)) |
11600 | return LoopInvariant; |
11601 | |
11602 | // This recurrence is variant w.r.t. L if any of its operands |
11603 | // are variant. |
11604 | for (auto *Op : AR->operands()) |
11605 | if (!isLoopInvariant(Op, L)) |
11606 | return LoopVariant; |
11607 | |
11608 | // Otherwise it's loop-invariant. |
11609 | return LoopInvariant; |
11610 | } |
11611 | case scAddExpr: |
11612 | case scMulExpr: |
11613 | case scUMaxExpr: |
11614 | case scSMaxExpr: { |
11615 | bool HasVarying = false; |
11616 | for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) { |
11617 | LoopDisposition D = getLoopDisposition(Op, L); |
11618 | if (D == LoopVariant) |
11619 | return LoopVariant; |
11620 | if (D == LoopComputable) |
11621 | HasVarying = true; |
11622 | } |
11623 | return HasVarying ? LoopComputable : LoopInvariant; |
11624 | } |
11625 | case scUDivExpr: { |
11626 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S); |
11627 | LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L); |
11628 | if (LD == LoopVariant) |
11629 | return LoopVariant; |
11630 | LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L); |
11631 | if (RD == LoopVariant) |
11632 | return LoopVariant; |
11633 | return (LD == LoopInvariant && RD == LoopInvariant) ? |
11634 | LoopInvariant : LoopComputable; |
11635 | } |
11636 | case scUnknown: |
11637 | // All non-instruction values are loop invariant. All instructions are loop |
11638 | // invariant if they are not contained in the specified loop. |
11639 | // Instructions are never considered invariant in the function body |
11640 | // (null loop) because they are defined within the "loop". |
11641 | if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) |
11642 | return (L && !L->contains(I)) ? LoopInvariant : LoopVariant; |
11643 | return LoopInvariant; |
11644 | case scCouldNotCompute: |
11645 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11645); |
11646 | } |
11647 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11647); |
11648 | } |
11649 | |
11650 | bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) { |
11651 | return getLoopDisposition(S, L) == LoopInvariant; |
11652 | } |
11653 | |
11654 | bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) { |
11655 | return getLoopDisposition(S, L) == LoopComputable; |
11656 | } |
11657 | |
11658 | ScalarEvolution::BlockDisposition |
11659 | ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) { |
11660 | auto &Values = BlockDispositions[S]; |
11661 | for (auto &V : Values) { |
11662 | if (V.getPointer() == BB) |
11663 | return V.getInt(); |
11664 | } |
11665 | Values.emplace_back(BB, DoesNotDominateBlock); |
11666 | BlockDisposition D = computeBlockDisposition(S, BB); |
11667 | auto &Values2 = BlockDispositions[S]; |
11668 | for (auto &V : make_range(Values2.rbegin(), Values2.rend())) { |
11669 | if (V.getPointer() == BB) { |
11670 | V.setInt(D); |
11671 | break; |
11672 | } |
11673 | } |
11674 | return D; |
11675 | } |
11676 | |
11677 | ScalarEvolution::BlockDisposition |
11678 | ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) { |
11679 | switch (static_cast<SCEVTypes>(S->getSCEVType())) { |
11680 | case scConstant: |
11681 | return ProperlyDominatesBlock; |
11682 | case scTruncate: |
11683 | case scZeroExtend: |
11684 | case scSignExtend: |
11685 | return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB); |
11686 | case scAddRecExpr: { |
11687 | // This uses a "dominates" query instead of "properly dominates" query |
11688 | // to test for proper dominance too, because the instruction which |
11689 | // produces the addrec's value is a PHI, and a PHI effectively properly |
11690 | // dominates its entire containing block. |
11691 | const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S); |
11692 | if (!DT.dominates(AR->getLoop()->getHeader(), BB)) |
11693 | return DoesNotDominateBlock; |
11694 | |
11695 | // Fall through into SCEVNAryExpr handling. |
11696 | LLVM_FALLTHROUGH[[clang::fallthrough]]; |
11697 | } |
11698 | case scAddExpr: |
11699 | case scMulExpr: |
11700 | case scUMaxExpr: |
11701 | case scSMaxExpr: { |
11702 | const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S); |
11703 | bool Proper = true; |
11704 | for (const SCEV *NAryOp : NAry->operands()) { |
11705 | BlockDisposition D = getBlockDisposition(NAryOp, BB); |
11706 | if (D == DoesNotDominateBlock) |
11707 | return DoesNotDominateBlock; |
11708 | if (D == DominatesBlock) |
11709 | Proper = false; |
11710 | } |
11711 | return Proper ? ProperlyDominatesBlock : DominatesBlock; |
11712 | } |
11713 | case scUDivExpr: { |
11714 | const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S); |
11715 | const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS(); |
11716 | BlockDisposition LD = getBlockDisposition(LHS, BB); |
11717 | if (LD == DoesNotDominateBlock) |
11718 | return DoesNotDominateBlock; |
11719 | BlockDisposition RD = getBlockDisposition(RHS, BB); |
11720 | if (RD == DoesNotDominateBlock) |
11721 | return DoesNotDominateBlock; |
11722 | return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ? |
11723 | ProperlyDominatesBlock : DominatesBlock; |
11724 | } |
11725 | case scUnknown: |
11726 | if (Instruction *I = |
11727 | dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) { |
11728 | if (I->getParent() == BB) |
11729 | return DominatesBlock; |
11730 | if (DT.properlyDominates(I->getParent(), BB)) |
11731 | return ProperlyDominatesBlock; |
11732 | return DoesNotDominateBlock; |
11733 | } |
11734 | return ProperlyDominatesBlock; |
11735 | case scCouldNotCompute: |
11736 | llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11736); |
11737 | } |
11738 | llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11738); |
11739 | } |
11740 | |
11741 | bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) { |
11742 | return getBlockDisposition(S, BB) >= DominatesBlock; |
11743 | } |
11744 | |
11745 | bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) { |
11746 | return getBlockDisposition(S, BB) == ProperlyDominatesBlock; |
11747 | } |
11748 | |
11749 | bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const { |
11750 | return SCEVExprContains(S, [&](const SCEV *Expr) { return Expr == Op; }); |
11751 | } |
11752 | |
11753 | bool ScalarEvolution::ExitLimit::hasOperand(const SCEV *S) const { |
11754 | auto IsS = [&](const SCEV *X) { return S == X; }; |
11755 | auto ContainsS = [&](const SCEV *X) { |
11756 | return !isa<SCEVCouldNotCompute>(X) && SCEVExprContains(X, IsS); |
11757 | }; |
11758 | return ContainsS(ExactNotTaken) || ContainsS(MaxNotTaken); |
11759 | } |
11760 | |
11761 | void |
11762 | ScalarEvolution::forgetMemoizedResults(const SCEV *S) { |
11763 | ValuesAtScopes.erase(S); |
11764 | LoopDispositions.erase(S); |
11765 | BlockDispositions.erase(S); |
11766 | UnsignedRanges.erase(S); |
11767 | SignedRanges.erase(S); |
11768 | ExprValueMap.erase(S); |
11769 | HasRecMap.erase(S); |
11770 | MinTrailingZerosCache.erase(S); |
11771 | |
11772 | for (auto I = PredicatedSCEVRewrites.begin(); |
11773 | I != PredicatedSCEVRewrites.end();) { |
11774 | std::pair<const SCEV *, const Loop *> Entry = I->first; |
11775 | if (Entry.first == S) |
11776 | PredicatedSCEVRewrites.erase(I++); |
11777 | else |
11778 | ++I; |
11779 | } |
11780 | |
11781 | auto RemoveSCEVFromBackedgeMap = |
11782 | [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) { |
11783 | for (auto I = Map.begin(), E = Map.end(); I != E;) { |
11784 | BackedgeTakenInfo &BEInfo = I->second; |
11785 | if (BEInfo.hasOperand(S, this)) { |
11786 | BEInfo.clear(); |
11787 | Map.erase(I++); |
11788 | } else |
11789 | ++I; |
11790 | } |
11791 | }; |
11792 | |
11793 | RemoveSCEVFromBackedgeMap(BackedgeTakenCounts); |
11794 | RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts); |
11795 | } |
11796 | |
11797 | void |
11798 | ScalarEvolution::getUsedLoops(const SCEV *S, |
11799 | SmallPtrSetImpl<const Loop *> &LoopsUsed) { |
11800 | struct FindUsedLoops { |
11801 | FindUsedLoops(SmallPtrSetImpl<const Loop *> &LoopsUsed) |
11802 | : LoopsUsed(LoopsUsed) {} |
11803 | SmallPtrSetImpl<const Loop *> &LoopsUsed; |
11804 | bool follow(const SCEV *S) { |
11805 | if (auto *AR = dyn_cast<SCEVAddRecExpr>(S)) |
11806 | LoopsUsed.insert(AR->getLoop()); |
11807 | return true; |
11808 | } |
11809 | |
11810 | bool isDone() const { return false; } |
11811 | }; |
11812 | |
11813 | FindUsedLoops F(LoopsUsed); |
11814 | SCEVTraversal<FindUsedLoops>(F).visitAll(S); |
11815 | } |
11816 | |
11817 | void ScalarEvolution::addToLoopUseLists(const SCEV *S) { |
11818 | SmallPtrSet<const Loop *, 8> LoopsUsed; |
11819 | getUsedLoops(S, LoopsUsed); |
11820 | for (auto *L : LoopsUsed) |
11821 | LoopUsers[L].push_back(S); |
11822 | } |
11823 | |
11824 | void ScalarEvolution::verify() const { |
11825 | ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this); |
11826 | ScalarEvolution SE2(F, TLI, AC, DT, LI); |
11827 | |
11828 | SmallVector<Loop *, 8> LoopStack(LI.begin(), LI.end()); |
11829 | |
11830 | // Map's SCEV expressions from one ScalarEvolution "universe" to another. |
11831 | struct SCEVMapper : public SCEVRewriteVisitor<SCEVMapper> { |
11832 | SCEVMapper(ScalarEvolution &SE) : SCEVRewriteVisitor<SCEVMapper>(SE) {} |
11833 | |
11834 | const SCEV *visitConstant(const SCEVConstant *Constant) { |
11835 | return SE.getConstant(Constant->getAPInt()); |
11836 | } |
11837 | |
11838 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
11839 | return SE.getUnknown(Expr->getValue()); |
11840 | } |
11841 | |
11842 | const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) { |
11843 | return SE.getCouldNotCompute(); |
11844 | } |
11845 | }; |
11846 | |
11847 | SCEVMapper SCM(SE2); |
11848 | |
11849 | while (!LoopStack.empty()) { |
11850 | auto *L = LoopStack.pop_back_val(); |
11851 | LoopStack.insert(LoopStack.end(), L->begin(), L->end()); |
11852 | |
11853 | auto *CurBECount = SCM.visit( |
11854 | const_cast<ScalarEvolution *>(this)->getBackedgeTakenCount(L)); |
11855 | auto *NewBECount = SE2.getBackedgeTakenCount(L); |
11856 | |
11857 | if (CurBECount == SE2.getCouldNotCompute() || |
11858 | NewBECount == SE2.getCouldNotCompute()) { |
11859 | // NB! This situation is legal, but is very suspicious -- whatever pass |
11860 | // change the loop to make a trip count go from could not compute to |
11861 | // computable or vice-versa *should have* invalidated SCEV. However, we |
11862 | // choose not to assert here (for now) since we don't want false |
11863 | // positives. |
11864 | continue; |
11865 | } |
11866 | |
11867 | if (containsUndefs(CurBECount) || containsUndefs(NewBECount)) { |
11868 | // SCEV treats "undef" as an unknown but consistent value (i.e. it does |
11869 | // not propagate undef aggressively). This means we can (and do) fail |
11870 | // verification in cases where a transform makes the trip count of a loop |
11871 | // go from "undef" to "undef+1" (say). The transform is fine, since in |
11872 | // both cases the loop iterates "undef" times, but SCEV thinks we |
11873 | // increased the trip count of the loop by 1 incorrectly. |
11874 | continue; |
11875 | } |
11876 | |
11877 | if (SE.getTypeSizeInBits(CurBECount->getType()) > |
11878 | SE.getTypeSizeInBits(NewBECount->getType())) |
11879 | NewBECount = SE2.getZeroExtendExpr(NewBECount, CurBECount->getType()); |
11880 | else if (SE.getTypeSizeInBits(CurBECount->getType()) < |
11881 | SE.getTypeSizeInBits(NewBECount->getType())) |
11882 | CurBECount = SE2.getZeroExtendExpr(CurBECount, NewBECount->getType()); |
11883 | |
11884 | auto *ConstantDelta = |
11885 | dyn_cast<SCEVConstant>(SE2.getMinusSCEV(CurBECount, NewBECount)); |
11886 | |
11887 | if (ConstantDelta && ConstantDelta->getAPInt() != 0) { |
11888 | dbgs() << "Trip Count Changed!\n"; |
11889 | dbgs() << "Old: " << *CurBECount << "\n"; |
11890 | dbgs() << "New: " << *NewBECount << "\n"; |
11891 | dbgs() << "Delta: " << *ConstantDelta << "\n"; |
11892 | std::abort(); |
11893 | } |
11894 | } |
11895 | } |
11896 | |
11897 | bool ScalarEvolution::invalidate( |
11898 | Function &F, const PreservedAnalyses &PA, |
11899 | FunctionAnalysisManager::Invalidator &Inv) { |
11900 | // Invalidate the ScalarEvolution object whenever it isn't preserved or one |
11901 | // of its dependencies is invalidated. |
11902 | auto PAC = PA.getChecker<ScalarEvolutionAnalysis>(); |
11903 | return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()) || |
11904 | Inv.invalidate<AssumptionAnalysis>(F, PA) || |
11905 | Inv.invalidate<DominatorTreeAnalysis>(F, PA) || |
11906 | Inv.invalidate<LoopAnalysis>(F, PA); |
11907 | } |
11908 | |
11909 | AnalysisKey ScalarEvolutionAnalysis::Key; |
11910 | |
11911 | ScalarEvolution ScalarEvolutionAnalysis::run(Function &F, |
11912 | FunctionAnalysisManager &AM) { |
11913 | return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F), |
11914 | AM.getResult<AssumptionAnalysis>(F), |
11915 | AM.getResult<DominatorTreeAnalysis>(F), |
11916 | AM.getResult<LoopAnalysis>(F)); |
11917 | } |
11918 | |
11919 | PreservedAnalyses |
11920 | ScalarEvolutionPrinterPass::run(Function &F, FunctionAnalysisManager &AM) { |
11921 | AM.getResult<ScalarEvolutionAnalysis>(F).print(OS); |
11922 | return PreservedAnalyses::all(); |
11923 | } |
11924 | |
11925 | INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry &Registry) { |
11926 | "Scalar Evolution Analysis", false, true)static void *initializeScalarEvolutionWrapperPassPassOnce(PassRegistry &Registry) { |
11927 | INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry); |
11928 | INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry); |
11929 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry); |
11930 | INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry); |
11931 | INITIALIZE_PASS_END(ScalarEvolutionWrapperPass, "scalar-evolution",PassInfo *PI = new PassInfo( "Scalar Evolution Analysis", "scalar-evolution" , &ScalarEvolutionWrapperPass::ID, PassInfo::NormalCtor_t (callDefaultCtor<ScalarEvolutionWrapperPass>), false, true ); Registry.registerPass(*PI, true); return PI; } static llvm ::once_flag InitializeScalarEvolutionWrapperPassPassFlag; void llvm::initializeScalarEvolutionWrapperPassPass(PassRegistry & Registry) { llvm::call_once(InitializeScalarEvolutionWrapperPassPassFlag , initializeScalarEvolutionWrapperPassPassOnce, std::ref(Registry )); } |
11932 | "Scalar Evolution Analysis", false, true)PassInfo *PI = new PassInfo( "Scalar Evolution Analysis", "scalar-evolution" , &ScalarEvolutionWrapperPass::ID, PassInfo::NormalCtor_t (callDefaultCtor<ScalarEvolutionWrapperPass>), false, true ); Registry.registerPass(*PI, true); return PI; } static llvm ::once_flag InitializeScalarEvolutionWrapperPassPassFlag; void llvm::initializeScalarEvolutionWrapperPassPass(PassRegistry & Registry) { llvm::call_once(InitializeScalarEvolutionWrapperPassPassFlag , initializeScalarEvolutionWrapperPassPassOnce, std::ref(Registry )); } |
11933 | |
11934 | char ScalarEvolutionWrapperPass::ID = 0; |
11935 | |
11936 | ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) { |
11937 | initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry()); |
11938 | } |
11939 | |
11940 | bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) { |
11941 | SE.reset(new ScalarEvolution( |
11942 | F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(), |
11943 | getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F), |
11944 | getAnalysis<DominatorTreeWrapperPass>().getDomTree(), |
11945 | getAnalysis<LoopInfoWrapperPass>().getLoopInfo())); |
11946 | return false; |
11947 | } |
11948 | |
11949 | void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); } |
11950 | |
11951 | void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const { |
11952 | SE->print(OS); |
11953 | } |
11954 | |
11955 | void ScalarEvolutionWrapperPass::verifyAnalysis() const { |
11956 | if (!VerifySCEV) |
11957 | return; |
11958 | |
11959 | SE->verify(); |
11960 | } |
11961 | |
11962 | void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { |
11963 | AU.setPreservesAll(); |
11964 | AU.addRequiredTransitive<AssumptionCacheTracker>(); |
11965 | AU.addRequiredTransitive<LoopInfoWrapperPass>(); |
11966 | AU.addRequiredTransitive<DominatorTreeWrapperPass>(); |
11967 | AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>(); |
11968 | } |
11969 | |
11970 | const SCEVPredicate *ScalarEvolution::getEqualPredicate(const SCEV *LHS, |
11971 | const SCEV *RHS) { |
11972 | FoldingSetNodeID ID; |
11973 | assert(LHS->getType() == RHS->getType() &&((LHS->getType() == RHS->getType() && "Type mismatch between LHS and RHS" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11974, __PRETTY_FUNCTION__)) |
11974 | "Type mismatch between LHS and RHS")((LHS->getType() == RHS->getType() && "Type mismatch between LHS and RHS" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"Type mismatch between LHS and RHS\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 11974, __PRETTY_FUNCTION__)); |
11975 | // Unique this node based on the arguments |
11976 | ID.AddInteger(SCEVPredicate::P_Equal); |
11977 | ID.AddPointer(LHS); |
11978 | ID.AddPointer(RHS); |
11979 | void *IP = nullptr; |
11980 | if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP)) |
11981 | return S; |
11982 | SCEVEqualPredicate *Eq = new (SCEVAllocator) |
11983 | SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS); |
11984 | UniquePreds.InsertNode(Eq, IP); |
11985 | return Eq; |
11986 | } |
11987 | |
11988 | const SCEVPredicate *ScalarEvolution::getWrapPredicate( |
11989 | const SCEVAddRecExpr *AR, |
11990 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags) { |
11991 | FoldingSetNodeID ID; |
11992 | // Unique this node based on the arguments |
11993 | ID.AddInteger(SCEVPredicate::P_Wrap); |
11994 | ID.AddPointer(AR); |
11995 | ID.AddInteger(AddedFlags); |
11996 | void *IP = nullptr; |
11997 | if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP)) |
11998 | return S; |
11999 | auto *OF = new (SCEVAllocator) |
12000 | SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags); |
12001 | UniquePreds.InsertNode(OF, IP); |
12002 | return OF; |
12003 | } |
12004 | |
12005 | namespace { |
12006 | |
12007 | class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> { |
12008 | public: |
12009 | |
12010 | /// Rewrites \p S in the context of a loop L and the SCEV predication |
12011 | /// infrastructure. |
12012 | /// |
12013 | /// If \p Pred is non-null, the SCEV expression is rewritten to respect the |
12014 | /// equivalences present in \p Pred. |
12015 | /// |
12016 | /// If \p NewPreds is non-null, rewrite is free to add further predicates to |
12017 | /// \p NewPreds such that the result will be an AddRecExpr. |
12018 | static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE, |
12019 | SmallPtrSetImpl<const SCEVPredicate *> *NewPreds, |
12020 | SCEVUnionPredicate *Pred) { |
12021 | SCEVPredicateRewriter Rewriter(L, SE, NewPreds, Pred); |
12022 | return Rewriter.visit(S); |
12023 | } |
12024 | |
12025 | const SCEV *visitUnknown(const SCEVUnknown *Expr) { |
12026 | if (Pred) { |
12027 | auto ExprPreds = Pred->getPredicatesForExpr(Expr); |
12028 | for (auto *Pred : ExprPreds) |
12029 | if (const auto *IPred = dyn_cast<SCEVEqualPredicate>(Pred)) |
12030 | if (IPred->getLHS() == Expr) |
12031 | return IPred->getRHS(); |
12032 | } |
12033 | return convertToAddRecWithPreds(Expr); |
12034 | } |
12035 | |
12036 | const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) { |
12037 | const SCEV *Operand = visit(Expr->getOperand()); |
12038 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand); |
12039 | if (AR && AR->getLoop() == L && AR->isAffine()) { |
12040 | // This couldn't be folded because the operand didn't have the nuw |
12041 | // flag. Add the nusw flag as an assumption that we could make. |
12042 | const SCEV *Step = AR->getStepRecurrence(SE); |
12043 | Type *Ty = Expr->getType(); |
12044 | if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW)) |
12045 | return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty), |
12046 | SE.getSignExtendExpr(Step, Ty), L, |
12047 | AR->getNoWrapFlags()); |
12048 | } |
12049 | return SE.getZeroExtendExpr(Operand, Expr->getType()); |
12050 | } |
12051 | |
12052 | const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) { |
12053 | const SCEV *Operand = visit(Expr->getOperand()); |
12054 | const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Operand); |
12055 | if (AR && AR->getLoop() == L && AR->isAffine()) { |
12056 | // This couldn't be folded because the operand didn't have the nsw |
12057 | // flag. Add the nssw flag as an assumption that we could make. |
12058 | const SCEV *Step = AR->getStepRecurrence(SE); |
12059 | Type *Ty = Expr->getType(); |
12060 | if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW)) |
12061 | return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty), |
12062 | SE.getSignExtendExpr(Step, Ty), L, |
12063 | AR->getNoWrapFlags()); |
12064 | } |
12065 | return SE.getSignExtendExpr(Operand, Expr->getType()); |
12066 | } |
12067 | |
12068 | private: |
12069 | explicit SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE, |
12070 | SmallPtrSetImpl<const SCEVPredicate *> *NewPreds, |
12071 | SCEVUnionPredicate *Pred) |
12072 | : SCEVRewriteVisitor(SE), NewPreds(NewPreds), Pred(Pred), L(L) {} |
12073 | |
12074 | bool addOverflowAssumption(const SCEVPredicate *P) { |
12075 | if (!NewPreds) { |
12076 | // Check if we've already made this assumption. |
12077 | return Pred && Pred->implies(P); |
12078 | } |
12079 | NewPreds->insert(P); |
12080 | return true; |
12081 | } |
12082 | |
12083 | bool addOverflowAssumption(const SCEVAddRecExpr *AR, |
12084 | SCEVWrapPredicate::IncrementWrapFlags AddedFlags) { |
12085 | auto *A = SE.getWrapPredicate(AR, AddedFlags); |
12086 | return addOverflowAssumption(A); |
12087 | } |
12088 | |
12089 | // If \p Expr represents a PHINode, we try to see if it can be represented |
12090 | // as an AddRec, possibly under a predicate (PHISCEVPred). If it is possible |
12091 | // to add this predicate as a runtime overflow check, we return the AddRec. |
12092 | // If \p Expr does not meet these conditions (is not a PHI node, or we |
12093 | // couldn't create an AddRec for it, or couldn't add the predicate), we just |
12094 | // return \p Expr. |
12095 | const SCEV *convertToAddRecWithPreds(const SCEVUnknown *Expr) { |
12096 | if (!isa<PHINode>(Expr->getValue())) |
12097 | return Expr; |
12098 | Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>> |
12099 | PredicatedRewrite = SE.createAddRecFromPHIWithCasts(Expr); |
12100 | if (!PredicatedRewrite) |
12101 | return Expr; |
12102 | for (auto *P : PredicatedRewrite->second){ |
12103 | // Wrap predicates from outer loops are not supported. |
12104 | if (auto *WP = dyn_cast<const SCEVWrapPredicate>(P)) { |
12105 | auto *AR = cast<const SCEVAddRecExpr>(WP->getExpr()); |
12106 | if (L != AR->getLoop()) |
12107 | return Expr; |
12108 | } |
12109 | if (!addOverflowAssumption(P)) |
12110 | return Expr; |
12111 | } |
12112 | return PredicatedRewrite->first; |
12113 | } |
12114 | |
12115 | SmallPtrSetImpl<const SCEVPredicate *> *NewPreds; |
12116 | SCEVUnionPredicate *Pred; |
12117 | const Loop *L; |
12118 | }; |
12119 | |
12120 | } // end anonymous namespace |
12121 | |
12122 | const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L, |
12123 | SCEVUnionPredicate &Preds) { |
12124 | return SCEVPredicateRewriter::rewrite(S, L, *this, nullptr, &Preds); |
12125 | } |
12126 | |
12127 | const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates( |
12128 | const SCEV *S, const Loop *L, |
12129 | SmallPtrSetImpl<const SCEVPredicate *> &Preds) { |
12130 | SmallPtrSet<const SCEVPredicate *, 4> TransformPreds; |
12131 | S = SCEVPredicateRewriter::rewrite(S, L, *this, &TransformPreds, nullptr); |
12132 | auto *AddRec = dyn_cast<SCEVAddRecExpr>(S); |
12133 | |
12134 | if (!AddRec) |
12135 | return nullptr; |
12136 | |
12137 | // Since the transformation was successful, we can now transfer the SCEV |
12138 | // predicates. |
12139 | for (auto *P : TransformPreds) |
12140 | Preds.insert(P); |
12141 | |
12142 | return AddRec; |
12143 | } |
12144 | |
12145 | /// SCEV predicates |
12146 | SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID, |
12147 | SCEVPredicateKind Kind) |
12148 | : FastID(ID), Kind(Kind) {} |
12149 | |
12150 | SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID, |
12151 | const SCEV *LHS, const SCEV *RHS) |
12152 | : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) { |
12153 | assert(LHS->getType() == RHS->getType() && "LHS and RHS types don't match")((LHS->getType() == RHS->getType() && "LHS and RHS types don't match" ) ? static_cast<void> (0) : __assert_fail ("LHS->getType() == RHS->getType() && \"LHS and RHS types don't match\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 12153, __PRETTY_FUNCTION__)); |
12154 | assert(LHS != RHS && "LHS and RHS are the same SCEV")((LHS != RHS && "LHS and RHS are the same SCEV") ? static_cast <void> (0) : __assert_fail ("LHS != RHS && \"LHS and RHS are the same SCEV\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 12154, __PRETTY_FUNCTION__)); |
12155 | } |
12156 | |
12157 | bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const { |
12158 | const auto *Op = dyn_cast<SCEVEqualPredicate>(N); |
12159 | |
12160 | if (!Op) |
12161 | return false; |
12162 | |
12163 | return Op->LHS == LHS && Op->RHS == RHS; |
12164 | } |
12165 | |
12166 | bool SCEVEqualPredicate::isAlwaysTrue() const { return false; } |
12167 | |
12168 | const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; } |
12169 | |
12170 | void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const { |
12171 | OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n"; |
12172 | } |
12173 | |
12174 | SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID, |
12175 | const SCEVAddRecExpr *AR, |
12176 | IncrementWrapFlags Flags) |
12177 | : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {} |
12178 | |
12179 | const SCEV *SCEVWrapPredicate::getExpr() const { return AR; } |
12180 | |
12181 | bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const { |
12182 | const auto *Op = dyn_cast<SCEVWrapPredicate>(N); |
12183 | |
12184 | return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags; |
12185 | } |
12186 | |
12187 | bool SCEVWrapPredicate::isAlwaysTrue() const { |
12188 | SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags(); |
12189 | IncrementWrapFlags IFlags = Flags; |
12190 | |
12191 | if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags) |
12192 | IFlags = clearFlags(IFlags, IncrementNSSW); |
12193 | |
12194 | return IFlags == IncrementAnyWrap; |
12195 | } |
12196 | |
12197 | void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const { |
12198 | OS.indent(Depth) << *getExpr() << " Added Flags: "; |
12199 | if (SCEVWrapPredicate::IncrementNUSW & getFlags()) |
12200 | OS << "<nusw>"; |
12201 | if (SCEVWrapPredicate::IncrementNSSW & getFlags()) |
12202 | OS << "<nssw>"; |
12203 | OS << "\n"; |
12204 | } |
12205 | |
12206 | SCEVWrapPredicate::IncrementWrapFlags |
12207 | SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR, |
12208 | ScalarEvolution &SE) { |
12209 | IncrementWrapFlags ImpliedFlags = IncrementAnyWrap; |
12210 | SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags(); |
12211 | |
12212 | // We can safely transfer the NSW flag as NSSW. |
12213 | if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags) |
12214 | ImpliedFlags = IncrementNSSW; |
12215 | |
12216 | if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) { |
12217 | // If the increment is positive, the SCEV NUW flag will also imply the |
12218 | // WrapPredicate NUSW flag. |
12219 | if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE))) |
12220 | if (Step->getValue()->getValue().isNonNegative()) |
12221 | ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW); |
12222 | } |
12223 | |
12224 | return ImpliedFlags; |
12225 | } |
12226 | |
12227 | /// Union predicates don't get cached so create a dummy set ID for it. |
12228 | SCEVUnionPredicate::SCEVUnionPredicate() |
12229 | : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {} |
12230 | |
12231 | bool SCEVUnionPredicate::isAlwaysTrue() const { |
12232 | return all_of(Preds, |
12233 | [](const SCEVPredicate *I) { return I->isAlwaysTrue(); }); |
12234 | } |
12235 | |
12236 | ArrayRef<const SCEVPredicate *> |
12237 | SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) { |
12238 | auto I = SCEVToPreds.find(Expr); |
12239 | if (I == SCEVToPreds.end()) |
12240 | return ArrayRef<const SCEVPredicate *>(); |
12241 | return I->second; |
12242 | } |
12243 | |
12244 | bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const { |
12245 | if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) |
12246 | return all_of(Set->Preds, |
12247 | [this](const SCEVPredicate *I) { return this->implies(I); }); |
12248 | |
12249 | auto ScevPredsIt = SCEVToPreds.find(N->getExpr()); |
12250 | if (ScevPredsIt == SCEVToPreds.end()) |
12251 | return false; |
12252 | auto &SCEVPreds = ScevPredsIt->second; |
12253 | |
12254 | return any_of(SCEVPreds, |
12255 | [N](const SCEVPredicate *I) { return I->implies(N); }); |
12256 | } |
12257 | |
12258 | const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; } |
12259 | |
12260 | void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const { |
12261 | for (auto Pred : Preds) |
12262 | Pred->print(OS, Depth); |
12263 | } |
12264 | |
12265 | void SCEVUnionPredicate::add(const SCEVPredicate *N) { |
12266 | if (const auto *Set = dyn_cast<SCEVUnionPredicate>(N)) { |
12267 | for (auto Pred : Set->Preds) |
12268 | add(Pred); |
12269 | return; |
12270 | } |
12271 | |
12272 | if (implies(N)) |
12273 | return; |
12274 | |
12275 | const SCEV *Key = N->getExpr(); |
12276 | assert(Key && "Only SCEVUnionPredicate doesn't have an "((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!" ) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 12277, __PRETTY_FUNCTION__)) |
12277 | " associated expression!")((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!" ) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\"" , "/build/llvm-toolchain-snapshot-8~svn350071/lib/Analysis/ScalarEvolution.cpp" , 12277, __PRETTY_FUNCTION__)); |
12278 | |
12279 | SCEVToPreds[Key].push_back(N); |
12280 | Preds.push_back(N); |
12281 | } |
12282 | |
12283 | PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE, |
12284 | Loop &L) |
12285 | : SE(SE), L(L) {} |
12286 | |
12287 | const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) { |
12288 | const SCEV *Expr = SE.getSCEV(V); |
12289 | RewriteEntry &Entry = RewriteMap[Expr]; |
12290 | |
12291 | // If we already have an entry and the version matches, return it. |
12292 | if (Entry.second && Generation == Entry.first) |
12293 | return Entry.second; |
12294 | |
12295 | // We found an entry but it's stale. Rewrite the stale entry |
12296 | // according to the current predicate. |
12297 | if (Entry.second) |
12298 | Expr = Entry.second; |
12299 | |
12300 | const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds); |
12301 | Entry = {Generation, NewSCEV}; |
12302 | |
12303 | return NewSCEV; |
12304 | } |
12305 | |
12306 | const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() { |
12307 | if (!BackedgeCount) { |
12308 | SCEVUnionPredicate BackedgePred; |
12309 | BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred); |
12310 | addPredicate(BackedgePred); |
12311 | } |
12312 | return BackedgeCount; |
12313 | } |
12314 | |
12315 | void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) { |
12316 | if (Preds.implies(&Pred)) |
12317 | return; |
12318 | Preds.add(&Pred); |
12319 | updateGeneration(); |
12320 | } |
12321 | |
12322 | const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const { |
12323 | return Preds; |
12324 | } |
12325 | |
12326 | void PredicatedScalarEvolution::updateGeneration() { |
12327 | // If the generation number wrapped recompute everything. |
12328 | if (++Generation == 0) { |
12329 | for (auto &II : RewriteMap) { |
12330 | const SCEV *Rewritten = II.second.second; |
12331 | II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)}; |
12332 | } |
12333 | } |
12334 | } |
12335 | |
12336 | void PredicatedScalarEvolution::setNoOverflow( |
12337 | Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) { |
12338 | const SCEV *Expr = getSCEV(V); |
12339 | const auto *AR = cast<SCEVAddRecExpr>(Expr); |
12340 | |
12341 | auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE); |
12342 | |
12343 | // Clear the statically implied flags. |
12344 | Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags); |
12345 | addPredicate(*SE.getWrapPredicate(AR, Flags)); |
12346 | |
12347 | auto II = FlagsMap.insert({V, Flags}); |
12348 | if (!II.second) |
12349 | II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second); |
12350 | } |
12351 | |
12352 | bool PredicatedScalarEvolution::hasNoOverflow( |
12353 | Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) { |
12354 | const SCEV *Expr = getSCEV(V); |
12355 | const auto *AR = cast<SCEVAddRecExpr>(Expr); |
12356 | |
12357 | Flags = SCEVWrapPredicate::clearFlags( |
12358 | Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE)); |
12359 | |
12360 | auto II = FlagsMap.find(V); |
12361 | |
12362 | if (II != FlagsMap.end()) |
12363 | Flags = SCEVWrapPredicate::clearFlags(Flags, II->second); |
12364 | |
12365 | return Flags == SCEVWrapPredicate::IncrementAnyWrap; |
12366 | } |
12367 | |
12368 | const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) { |
12369 | const SCEV *Expr = this->getSCEV(V); |
12370 | SmallPtrSet<const SCEVPredicate *, 4> NewPreds; |
12371 | auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, NewPreds); |
12372 | |
12373 | if (!New) |
12374 | return nullptr; |
12375 | |
12376 | for (auto *P : NewPreds) |
12377 | Preds.add(P); |
12378 | |
12379 | updateGeneration(); |
12380 | RewriteMap[SE.getSCEV(V)] = {Generation, New}; |
12381 | return New; |
12382 | } |
12383 | |
12384 | PredicatedScalarEvolution::PredicatedScalarEvolution( |
12385 | const PredicatedScalarEvolution &Init) |
12386 | : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds), |
12387 | Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) { |
12388 | for (const auto &I : Init.FlagsMap) |
12389 | FlagsMap.insert(I); |
12390 | } |
12391 | |
12392 | void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const { |
12393 | // For each block. |
12394 | for (auto *BB : L.getBlocks()) |
12395 | for (auto &I : *BB) { |
12396 | if (!SE.isSCEVable(I.getType())) |
12397 | continue; |
12398 | |
12399 | auto *Expr = SE.getSCEV(&I); |
12400 | auto II = RewriteMap.find(Expr); |
12401 | |
12402 | if (II == RewriteMap.end()) |
12403 | continue; |
12404 | |
12405 | // Don't print things that are not interesting. |
12406 | if (II->second.second == Expr) |
12407 | continue; |
12408 | |
12409 | OS.indent(Depth) << "[PSE]" << I << ":\n"; |
12410 | OS.indent(Depth + 2) << *Expr << "\n"; |
12411 | OS.indent(Depth + 2) << "--> " << *II->second.second << "\n"; |
12412 | } |
12413 | } |
12414 | |
12415 | // Match the mathematical pattern A - (A / B) * B, where A and B can be |
12416 | // arbitrary expressions. |
12417 | // It's not always easy, as A and B can be folded (imagine A is X / 2, and B is |
12418 | // 4, A / B becomes X / 8). |
12419 | bool ScalarEvolution::matchURem(const SCEV *Expr, const SCEV *&LHS, |
12420 | const SCEV *&RHS) { |
12421 | const auto *Add = dyn_cast<SCEVAddExpr>(Expr); |
12422 | if (Add == nullptr || Add->getNumOperands() != 2) |
12423 | return false; |
12424 | |
12425 | const SCEV *A = Add->getOperand(1); |
12426 | const auto *Mul = dyn_cast<SCEVMulExpr>(Add->getOperand(0)); |
12427 | |
12428 | if (Mul == nullptr) |
12429 | return false; |
12430 | |
12431 | const auto MatchURemWithDivisor = [&](const SCEV *B) { |
12432 | // (SomeExpr + (-(SomeExpr / B) * B)). |
12433 | if (Expr == getURemExpr(A, B)) { |
12434 | LHS = A; |
12435 | RHS = B; |
12436 | return true; |
12437 | } |
12438 | return false; |
12439 | }; |
12440 | |
12441 | // (SomeExpr + (-1 * (SomeExpr / B) * B)). |
12442 | if (Mul->getNumOperands() == 3 && isa<SCEVConstant>(Mul->getOperand(0))) |
12443 | return MatchURemWithDivisor(Mul->getOperand(1)) || |
12444 | MatchURemWithDivisor(Mul->getOperand(2)); |
12445 | |
12446 | // (SomeExpr + ((-SomeExpr / B) * B)) or (SomeExpr + ((SomeExpr / B) * -B)). |
12447 | if (Mul->getNumOperands() == 2) |
12448 | return MatchURemWithDivisor(Mul->getOperand(1)) || |
12449 | MatchURemWithDivisor(Mul->getOperand(0)) || |
12450 | MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(1))) || |
12451 | MatchURemWithDivisor(getNegativeSCEV(Mul->getOperand(0))); |
12452 | return false; |
12453 | } |