Bug Summary

File:lib/Analysis/ScalarEvolution.cpp
Warning:line 9392, column 15
Value stored to 'MaxBECount' during its initialization is never read

Annotated Source Code

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/Optional.h"
63#include "llvm/ADT/STLExtras.h"
64#include "llvm/ADT/ScopeExit.h"
65#include "llvm/ADT/Sequence.h"
66#include "llvm/ADT/SmallPtrSet.h"
67#include "llvm/ADT/Statistic.h"
68#include "llvm/Analysis/AssumptionCache.h"
69#include "llvm/Analysis/ConstantFolding.h"
70#include "llvm/Analysis/InstructionSimplify.h"
71#include "llvm/Analysis/LoopInfo.h"
72#include "llvm/Analysis/ScalarEvolutionExpressions.h"
73#include "llvm/Analysis/TargetLibraryInfo.h"
74#include "llvm/Analysis/ValueTracking.h"
75#include "llvm/IR/ConstantRange.h"
76#include "llvm/IR/Constants.h"
77#include "llvm/IR/DataLayout.h"
78#include "llvm/IR/DerivedTypes.h"
79#include "llvm/IR/Dominators.h"
80#include "llvm/IR/GetElementPtrTypeIterator.h"
81#include "llvm/IR/GlobalAlias.h"
82#include "llvm/IR/GlobalVariable.h"
83#include "llvm/IR/InstIterator.h"
84#include "llvm/IR/Instructions.h"
85#include "llvm/IR/LLVMContext.h"
86#include "llvm/IR/Metadata.h"
87#include "llvm/IR/Operator.h"
88#include "llvm/IR/PatternMatch.h"
89#include "llvm/Support/CommandLine.h"
90#include "llvm/Support/Debug.h"
91#include "llvm/Support/ErrorHandling.h"
92#include "llvm/Support/KnownBits.h"
93#include "llvm/Support/MathExtras.h"
94#include "llvm/Support/SaveAndRestore.h"
95#include "llvm/Support/raw_ostream.h"
96#include <algorithm>
97using namespace llvm;
98
99#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
100
101STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
, {0}, false}
102 "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}
;
103STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, false}
104 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, false}
;
105STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, false}
106 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, false}
;
107STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
, {0}, false}
108 "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}
;
109
110static cl::opt<unsigned>
111MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
112 cl::desc("Maximum number of iterations SCEV will "
113 "symbolically execute a constant "
114 "derived loop"),
115 cl::init(100));
116
117// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
118static cl::opt<bool>
119VerifySCEV("verify-scev",
120 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
121static cl::opt<bool>
122 VerifySCEVMap("verify-scev-maps",
123 cl::desc("Verify no dangling value in ScalarEvolution's "
124 "ExprValueMap (slow)"));
125
126static cl::opt<unsigned> MulOpsInlineThreshold(
127 "scev-mulops-inline-threshold", cl::Hidden,
128 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
129 cl::init(32));
130
131static cl::opt<unsigned> AddOpsInlineThreshold(
132 "scev-addops-inline-threshold", cl::Hidden,
133 cl::desc("Threshold for inlining addition operands into a SCEV"),
134 cl::init(500));
135
136static cl::opt<unsigned> MaxSCEVCompareDepth(
137 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
138 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
139 cl::init(32));
140
141static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
142 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
143 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
144 cl::init(2));
145
146static cl::opt<unsigned> MaxValueCompareDepth(
147 "scalar-evolution-max-value-compare-depth", cl::Hidden,
148 cl::desc("Maximum depth of recursive value complexity comparisons"),
149 cl::init(2));
150
151static cl::opt<unsigned>
152 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
153 cl::desc("Maximum depth of recursive arithmetics"),
154 cl::init(32));
155
156static cl::opt<unsigned> MaxConstantEvolvingDepth(
157 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
158 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
159
160//===----------------------------------------------------------------------===//
161// SCEV class definitions
162//===----------------------------------------------------------------------===//
163
164//===----------------------------------------------------------------------===//
165// Implementation of the SCEV class.
166//
167
168#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
169LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
170 print(dbgs());
171 dbgs() << '\n';
172}
173#endif
174
175void SCEV::print(raw_ostream &OS) const {
176 switch (static_cast<SCEVTypes>(getSCEVType())) {
177 case scConstant:
178 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
179 return;
180 case scTruncate: {
181 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
182 const SCEV *Op = Trunc->getOperand();
183 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
184 << *Trunc->getType() << ")";
185 return;
186 }
187 case scZeroExtend: {
188 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
189 const SCEV *Op = ZExt->getOperand();
190 OS << "(zext " << *Op->getType() << " " << *Op << " to "
191 << *ZExt->getType() << ")";
192 return;
193 }
194 case scSignExtend: {
195 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
196 const SCEV *Op = SExt->getOperand();
197 OS << "(sext " << *Op->getType() << " " << *Op << " to "
198 << *SExt->getType() << ")";
199 return;
200 }
201 case scAddRecExpr: {
202 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
203 OS << "{" << *AR->getOperand(0);
204 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
205 OS << ",+," << *AR->getOperand(i);
206 OS << "}<";
207 if (AR->hasNoUnsignedWrap())
208 OS << "nuw><";
209 if (AR->hasNoSignedWrap())
210 OS << "nsw><";
211 if (AR->hasNoSelfWrap() &&
212 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
213 OS << "nw><";
214 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
215 OS << ">";
216 return;
217 }
218 case scAddExpr:
219 case scMulExpr:
220 case scUMaxExpr:
221 case scSMaxExpr: {
222 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
223 const char *OpStr = nullptr;
224 switch (NAry->getSCEVType()) {
225 case scAddExpr: OpStr = " + "; break;
226 case scMulExpr: OpStr = " * "; break;
227 case scUMaxExpr: OpStr = " umax "; break;
228 case scSMaxExpr: OpStr = " smax "; break;
229 }
230 OS << "(";
231 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
232 I != E; ++I) {
233 OS << **I;
234 if (std::next(I) != E)
235 OS << OpStr;
236 }
237 OS << ")";
238 switch (NAry->getSCEVType()) {
239 case scAddExpr:
240 case scMulExpr:
241 if (NAry->hasNoUnsignedWrap())
242 OS << "<nuw>";
243 if (NAry->hasNoSignedWrap())
244 OS << "<nsw>";
245 }
246 return;
247 }
248 case scUDivExpr: {
249 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
250 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
251 return;
252 }
253 case scUnknown: {
254 const SCEVUnknown *U = cast<SCEVUnknown>(this);
255 Type *AllocTy;
256 if (U->isSizeOf(AllocTy)) {
257 OS << "sizeof(" << *AllocTy << ")";
258 return;
259 }
260 if (U->isAlignOf(AllocTy)) {
261 OS << "alignof(" << *AllocTy << ")";
262 return;
263 }
264
265 Type *CTy;
266 Constant *FieldNo;
267 if (U->isOffsetOf(CTy, FieldNo)) {
268 OS << "offsetof(" << *CTy << ", ";
269 FieldNo->printAsOperand(OS, false);
270 OS << ")";
271 return;
272 }
273
274 // Otherwise just print it normally.
275 U->getValue()->printAsOperand(OS, false);
276 return;
277 }
278 case scCouldNotCompute:
279 OS << "***COULDNOTCOMPUTE***";
280 return;
281 }
282 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 282)
;
283}
284
285Type *SCEV::getType() const {
286 switch (static_cast<SCEVTypes>(getSCEVType())) {
287 case scConstant:
288 return cast<SCEVConstant>(this)->getType();
289 case scTruncate:
290 case scZeroExtend:
291 case scSignExtend:
292 return cast<SCEVCastExpr>(this)->getType();
293 case scAddRecExpr:
294 case scMulExpr:
295 case scUMaxExpr:
296 case scSMaxExpr:
297 return cast<SCEVNAryExpr>(this)->getType();
298 case scAddExpr:
299 return cast<SCEVAddExpr>(this)->getType();
300 case scUDivExpr:
301 return cast<SCEVUDivExpr>(this)->getType();
302 case scUnknown:
303 return cast<SCEVUnknown>(this)->getType();
304 case scCouldNotCompute:
305 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 305)
;
306 }
307 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 307)
;
308}
309
310bool SCEV::isZero() const {
311 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
312 return SC->getValue()->isZero();
313 return false;
314}
315
316bool SCEV::isOne() const {
317 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
318 return SC->getValue()->isOne();
319 return false;
320}
321
322bool SCEV::isAllOnesValue() const {
323 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
324 return SC->getValue()->isAllOnesValue();
325 return false;
326}
327
328bool SCEV::isNonConstantNegative() const {
329 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
330 if (!Mul) return false;
331
332 // If there is a constant factor, it will be first.
333 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
334 if (!SC) return false;
335
336 // Return true if the value is negative, this matches things like (-42 * V).
337 return SC->getAPInt().isNegative();
338}
339
340SCEVCouldNotCompute::SCEVCouldNotCompute() :
341 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}
342
343bool SCEVCouldNotCompute::classof(const SCEV *S) {
344 return S->getSCEVType() == scCouldNotCompute;
345}
346
347const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
348 FoldingSetNodeID ID;
349 ID.AddInteger(scConstant);
350 ID.AddPointer(V);
351 void *IP = nullptr;
352 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
353 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
354 UniqueSCEVs.InsertNode(S, IP);
355 return S;
356}
357
358const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
359 return getConstant(ConstantInt::get(getContext(), Val));
360}
361
362const SCEV *
363ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
364 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
365 return getConstant(ConstantInt::get(ITy, V, isSigned));
366}
367
368SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
369 unsigned SCEVTy, const SCEV *op, Type *ty)
370 : SCEV(ID, SCEVTy), Op(op), Ty(ty) {}
371
372SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
373 const SCEV *op, Type *ty)
374 : SCEVCastExpr(ID, scTruncate, op, ty) {
375 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 377, __PRETTY_FUNCTION__))
376 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 377, __PRETTY_FUNCTION__))
377 "Cannot truncate non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 377, __PRETTY_FUNCTION__))
;
378}
379
380SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
381 const SCEV *op, Type *ty)
382 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
383 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 385, __PRETTY_FUNCTION__))
384 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 385, __PRETTY_FUNCTION__))
385 "Cannot zero extend non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 385, __PRETTY_FUNCTION__))
;
386}
387
388SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
389 const SCEV *op, Type *ty)
390 : SCEVCastExpr(ID, scSignExtend, op, ty) {
391 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 393, __PRETTY_FUNCTION__))
392 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 393, __PRETTY_FUNCTION__))
393 "Cannot sign extend non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 393, __PRETTY_FUNCTION__))
;
394}
395
396void SCEVUnknown::deleted() {
397 // Clear this SCEVUnknown from various maps.
398 SE->forgetMemoizedResults(this);
399
400 // Remove this SCEVUnknown from the uniquing map.
401 SE->UniqueSCEVs.RemoveNode(this);
402
403 // Release the value.
404 setValPtr(nullptr);
405}
406
407void SCEVUnknown::allUsesReplacedWith(Value *New) {
408 // Clear this SCEVUnknown from various maps.
409 SE->forgetMemoizedResults(this);
410
411 // Remove this SCEVUnknown from the uniquing map.
412 SE->UniqueSCEVs.RemoveNode(this);
413
414 // Update this SCEVUnknown to point to the new value. This is needed
415 // because there may still be outstanding SCEVs which still point to
416 // this SCEVUnknown.
417 setValPtr(New);
418}
419
420bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
421 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
422 if (VCE->getOpcode() == Instruction::PtrToInt)
423 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
424 if (CE->getOpcode() == Instruction::GetElementPtr &&
425 CE->getOperand(0)->isNullValue() &&
426 CE->getNumOperands() == 2)
427 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
428 if (CI->isOne()) {
429 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
430 ->getElementType();
431 return true;
432 }
433
434 return false;
435}
436
437bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
438 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
439 if (VCE->getOpcode() == Instruction::PtrToInt)
440 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
441 if (CE->getOpcode() == Instruction::GetElementPtr &&
442 CE->getOperand(0)->isNullValue()) {
443 Type *Ty =
444 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
445 if (StructType *STy = dyn_cast<StructType>(Ty))
446 if (!STy->isPacked() &&
447 CE->getNumOperands() == 3 &&
448 CE->getOperand(1)->isNullValue()) {
449 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
450 if (CI->isOne() &&
451 STy->getNumElements() == 2 &&
452 STy->getElementType(0)->isIntegerTy(1)) {
453 AllocTy = STy->getElementType(1);
454 return true;
455 }
456 }
457 }
458
459 return false;
460}
461
462bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
463 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
464 if (VCE->getOpcode() == Instruction::PtrToInt)
465 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
466 if (CE->getOpcode() == Instruction::GetElementPtr &&
467 CE->getNumOperands() == 3 &&
468 CE->getOperand(0)->isNullValue() &&
469 CE->getOperand(1)->isNullValue()) {
470 Type *Ty =
471 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
472 // Ignore vector types here so that ScalarEvolutionExpander doesn't
473 // emit getelementptrs that index into vectors.
474 if (Ty->isStructTy() || Ty->isArrayTy()) {
475 CTy = Ty;
476 FieldNo = CE->getOperand(2);
477 return true;
478 }
479 }
480
481 return false;
482}
483
484//===----------------------------------------------------------------------===//
485// SCEV Utilities
486//===----------------------------------------------------------------------===//
487
488/// Compare the two values \p LV and \p RV in terms of their "complexity" where
489/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
490/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
491/// have been previously deemed to be "equally complex" by this routine. It is
492/// intended to avoid exponential time complexity in cases like:
493///
494/// %a = f(%x, %y)
495/// %b = f(%a, %a)
496/// %c = f(%b, %b)
497///
498/// %d = f(%x, %y)
499/// %e = f(%d, %d)
500/// %f = f(%e, %e)
501///
502/// CompareValueComplexity(%f, %c)
503///
504/// Since we do not continue running this routine on expression trees once we
505/// have seen unequal values, there is no need to track them in the cache.
506static int
507CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache,
508 const LoopInfo *const LI, Value *LV, Value *RV,
509 unsigned Depth) {
510 if (Depth > MaxValueCompareDepth || EqCache.count({LV, RV}))
511 return 0;
512
513 // Order pointer values after integer values. This helps SCEVExpander form
514 // GEPs.
515 bool LIsPointer = LV->getType()->isPointerTy(),
516 RIsPointer = RV->getType()->isPointerTy();
517 if (LIsPointer != RIsPointer)
518 return (int)LIsPointer - (int)RIsPointer;
519
520 // Compare getValueID values.
521 unsigned LID = LV->getValueID(), RID = RV->getValueID();
522 if (LID != RID)
523 return (int)LID - (int)RID;
524
525 // Sort arguments by their position.
526 if (const auto *LA = dyn_cast<Argument>(LV)) {
527 const auto *RA = cast<Argument>(RV);
528 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
529 return (int)LArgNo - (int)RArgNo;
530 }
531
532 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
533 const auto *RGV = cast<GlobalValue>(RV);
534
535 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
536 auto LT = GV->getLinkage();
537 return !(GlobalValue::isPrivateLinkage(LT) ||
538 GlobalValue::isInternalLinkage(LT));
539 };
540
541 // Use the names to distinguish the two values, but only if the
542 // names are semantically important.
543 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
544 return LGV->getName().compare(RGV->getName());
545 }
546
547 // For instructions, compare their loop depth, and their operand count. This
548 // is pretty loose.
549 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
550 const auto *RInst = cast<Instruction>(RV);
551
552 // Compare loop depths.
553 const BasicBlock *LParent = LInst->getParent(),
554 *RParent = RInst->getParent();
555 if (LParent != RParent) {
556 unsigned LDepth = LI->getLoopDepth(LParent),
557 RDepth = LI->getLoopDepth(RParent);
558 if (LDepth != RDepth)
559 return (int)LDepth - (int)RDepth;
560 }
561
562 // Compare the number of operands.
563 unsigned LNumOps = LInst->getNumOperands(),
564 RNumOps = RInst->getNumOperands();
565 if (LNumOps != RNumOps)
566 return (int)LNumOps - (int)RNumOps;
567
568 for (unsigned Idx : seq(0u, LNumOps)) {
569 int Result =
570 CompareValueComplexity(EqCache, LI, LInst->getOperand(Idx),
571 RInst->getOperand(Idx), Depth + 1);
572 if (Result != 0)
573 return Result;
574 }
575 }
576
577 EqCache.insert({LV, RV});
578 return 0;
579}
580
581// Return negative, zero, or positive, if LHS is less than, equal to, or greater
582// than RHS, respectively. A three-way result allows recursive comparisons to be
583// more efficient.
584static int CompareSCEVComplexity(
585 SmallSet<std::pair<const SCEV *, const SCEV *>, 8> &EqCacheSCEV,
586 const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS,
587 DominatorTree &DT, unsigned Depth = 0) {
588 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
589 if (LHS == RHS)
590 return 0;
591
592 // Primarily, sort the SCEVs by their getSCEVType().
593 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
594 if (LType != RType)
595 return (int)LType - (int)RType;
596
597 if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.count({LHS, RHS}))
598 return 0;
599 // Aside from the getSCEVType() ordering, the particular ordering
600 // isn't very important except that it's beneficial to be consistent,
601 // so that (a + b) and (b + a) don't end up as different expressions.
602 switch (static_cast<SCEVTypes>(LType)) {
603 case scUnknown: {
604 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
605 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
606
607 SmallSet<std::pair<Value *, Value *>, 8> EqCache;
608 int X = CompareValueComplexity(EqCache, LI, LU->getValue(), RU->getValue(),
609 Depth + 1);
610 if (X == 0)
611 EqCacheSCEV.insert({LHS, RHS});
612 return X;
613 }
614
615 case scConstant: {
616 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
617 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
618
619 // Compare constant values.
620 const APInt &LA = LC->getAPInt();
621 const APInt &RA = RC->getAPInt();
622 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
623 if (LBitWidth != RBitWidth)
624 return (int)LBitWidth - (int)RBitWidth;
625 return LA.ult(RA) ? -1 : 1;
626 }
627
628 case scAddRecExpr: {
629 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
630 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
631
632 // There is always a dominance between two recs that are used by one SCEV,
633 // so we can safely sort recs by loop header dominance. We require such
634 // order in getAddExpr.
635 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
636 if (LLoop != RLoop) {
637 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
638 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 638, __PRETTY_FUNCTION__))
;
639 if (DT.dominates(LHead, RHead))
640 return 1;
641 else
642 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 643, __PRETTY_FUNCTION__))
643 "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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 643, __PRETTY_FUNCTION__))
;
644 return -1;
645 }
646
647 // Addrec complexity grows with operand count.
648 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
649 if (LNumOps != RNumOps)
650 return (int)LNumOps - (int)RNumOps;
651
652 // Lexicographically compare.
653 for (unsigned i = 0; i != LNumOps; ++i) {
654 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LA->getOperand(i),
655 RA->getOperand(i), DT, Depth + 1);
656 if (X != 0)
657 return X;
658 }
659 EqCacheSCEV.insert({LHS, RHS});
660 return 0;
661 }
662
663 case scAddExpr:
664 case scMulExpr:
665 case scSMaxExpr:
666 case scUMaxExpr: {
667 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
668 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
669
670 // Lexicographically compare n-ary expressions.
671 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
672 if (LNumOps != RNumOps)
673 return (int)LNumOps - (int)RNumOps;
674
675 for (unsigned i = 0; i != LNumOps; ++i) {
676 if (i >= RNumOps)
677 return 1;
678 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getOperand(i),
679 RC->getOperand(i), DT, Depth + 1);
680 if (X != 0)
681 return X;
682 }
683 EqCacheSCEV.insert({LHS, RHS});
684 return 0;
685 }
686
687 case scUDivExpr: {
688 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
689 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
690
691 // Lexicographically compare udiv expressions.
692 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getLHS(), RC->getLHS(),
693 DT, Depth + 1);
694 if (X != 0)
695 return X;
696 X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getRHS(), RC->getRHS(), DT,
697 Depth + 1);
698 if (X == 0)
699 EqCacheSCEV.insert({LHS, RHS});
700 return X;
701 }
702
703 case scTruncate:
704 case scZeroExtend:
705 case scSignExtend: {
706 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
707 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
708
709 // Compare cast expressions by operand.
710 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getOperand(),
711 RC->getOperand(), DT, Depth + 1);
712 if (X == 0)
713 EqCacheSCEV.insert({LHS, RHS});
714 return X;
715 }
716
717 case scCouldNotCompute:
718 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 718)
;
719 }
720 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 720)
;
721}
722
723/// Given a list of SCEV objects, order them by their complexity, and group
724/// objects of the same complexity together by value. When this routine is
725/// finished, we know that any duplicates in the vector are consecutive and that
726/// complexity is monotonically increasing.
727///
728/// Note that we go take special precautions to ensure that we get deterministic
729/// results from this routine. In other words, we don't want the results of
730/// this to depend on where the addresses of various SCEV objects happened to
731/// land in memory.
732///
733static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
734 LoopInfo *LI, DominatorTree &DT) {
735 if (Ops.size() < 2) return; // Noop
736
737 SmallSet<std::pair<const SCEV *, const SCEV *>, 8> EqCache;
738 if (Ops.size() == 2) {
739 // This is the common case, which also happens to be trivially simple.
740 // Special case it.
741 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
742 if (CompareSCEVComplexity(EqCache, LI, RHS, LHS, DT) < 0)
743 std::swap(LHS, RHS);
744 return;
745 }
746
747 // Do the rough sort by complexity.
748 std::stable_sort(Ops.begin(), Ops.end(),
749 [&EqCache, LI, &DT](const SCEV *LHS, const SCEV *RHS) {
750 return
751 CompareSCEVComplexity(EqCache, LI, LHS, RHS, DT) < 0;
752 });
753
754 // Now that we are sorted by complexity, group elements of the same
755 // complexity. Note that this is, at worst, N^2, but the vector is likely to
756 // be extremely short in practice. Note that we take this approach because we
757 // do not want to depend on the addresses of the objects we are grouping.
758 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
759 const SCEV *S = Ops[i];
760 unsigned Complexity = S->getSCEVType();
761
762 // If there are any objects of the same complexity and same value as this
763 // one, group them.
764 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
765 if (Ops[j] == S) { // Found a duplicate.
766 // Move it to immediately after i'th element.
767 std::swap(Ops[i+1], Ops[j]);
768 ++i; // no need to rescan it.
769 if (i == e-2) return; // Done!
770 }
771 }
772 }
773}
774
775// Returns the size of the SCEV S.
776static inline int sizeOfSCEV(const SCEV *S) {
777 struct FindSCEVSize {
778 int Size;
779 FindSCEVSize() : Size(0) {}
780
781 bool follow(const SCEV *S) {
782 ++Size;
783 // Keep looking at all operands of S.
784 return true;
785 }
786 bool isDone() const {
787 return false;
788 }
789 };
790
791 FindSCEVSize F;
792 SCEVTraversal<FindSCEVSize> ST(F);
793 ST.visitAll(S);
794 return F.Size;
795}
796
797namespace {
798
799struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
800public:
801 // Computes the Quotient and Remainder of the division of Numerator by
802 // Denominator.
803 static void divide(ScalarEvolution &SE, const SCEV *Numerator,
804 const SCEV *Denominator, const SCEV **Quotient,
805 const SCEV **Remainder) {
806 assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV"
) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 806, __PRETTY_FUNCTION__))
;
807
808 SCEVDivision D(SE, Numerator, Denominator);
809
810 // Check for the trivial case here to avoid having to check for it in the
811 // rest of the code.
812 if (Numerator == Denominator) {
813 *Quotient = D.One;
814 *Remainder = D.Zero;
815 return;
816 }
817
818 if (Numerator->isZero()) {
819 *Quotient = D.Zero;
820 *Remainder = D.Zero;
821 return;
822 }
823
824 // A simple case when N/1. The quotient is N.
825 if (Denominator->isOne()) {
826 *Quotient = Numerator;
827 *Remainder = D.Zero;
828 return;
829 }
830
831 // Split the Denominator when it is a product.
832 if (const SCEVMulExpr *T = dyn_cast<SCEVMulExpr>(Denominator)) {
833 const SCEV *Q, *R;
834 *Quotient = Numerator;
835 for (const SCEV *Op : T->operands()) {
836 divide(SE, *Quotient, Op, &Q, &R);
837 *Quotient = Q;
838
839 // Bail out when the Numerator is not divisible by one of the terms of
840 // the Denominator.
841 if (!R->isZero()) {
842 *Quotient = D.Zero;
843 *Remainder = Numerator;
844 return;
845 }
846 }
847 *Remainder = D.Zero;
848 return;
849 }
850
851 D.visit(Numerator);
852 *Quotient = D.Quotient;
853 *Remainder = D.Remainder;
854 }
855
856 // Except in the trivial case described above, we do not know how to divide
857 // Expr by Denominator for the following functions with empty implementation.
858 void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
859 void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {}
860 void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {}
861 void visitUDivExpr(const SCEVUDivExpr *Numerator) {}
862 void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {}
863 void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {}
864 void visitUnknown(const SCEVUnknown *Numerator) {}
865 void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {}
866
867 void visitConstant(const SCEVConstant *Numerator) {
868 if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
869 APInt NumeratorVal = Numerator->getAPInt();
870 APInt DenominatorVal = D->getAPInt();
871 uint32_t NumeratorBW = NumeratorVal.getBitWidth();
872 uint32_t DenominatorBW = DenominatorVal.getBitWidth();
873
874 if (NumeratorBW > DenominatorBW)
875 DenominatorVal = DenominatorVal.sext(NumeratorBW);
876 else if (NumeratorBW < DenominatorBW)
877 NumeratorVal = NumeratorVal.sext(DenominatorBW);
878
879 APInt QuotientVal(NumeratorVal.getBitWidth(), 0);
880 APInt RemainderVal(NumeratorVal.getBitWidth(), 0);
881 APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal);
882 Quotient = SE.getConstant(QuotientVal);
883 Remainder = SE.getConstant(RemainderVal);
884 return;
885 }
886 }
887
888 void visitAddRecExpr(const SCEVAddRecExpr *Numerator) {
889 const SCEV *StartQ, *StartR, *StepQ, *StepR;
890 if (!Numerator->isAffine())
891 return cannotDivide(Numerator);
892 divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR);
893 divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR);
894 // Bail out if the types do not match.
895 Type *Ty = Denominator->getType();
896 if (Ty != StartQ->getType() || Ty != StartR->getType() ||
897 Ty != StepQ->getType() || Ty != StepR->getType())
898 return cannotDivide(Numerator);
899 Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(),
900 Numerator->getNoWrapFlags());
901 Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(),
902 Numerator->getNoWrapFlags());
903 }
904
905 void visitAddExpr(const SCEVAddExpr *Numerator) {
906 SmallVector<const SCEV *, 2> Qs, Rs;
907 Type *Ty = Denominator->getType();
908
909 for (const SCEV *Op : Numerator->operands()) {
910 const SCEV *Q, *R;
911 divide(SE, Op, Denominator, &Q, &R);
912
913 // Bail out if types do not match.
914 if (Ty != Q->getType() || Ty != R->getType())
915 return cannotDivide(Numerator);
916
917 Qs.push_back(Q);
918 Rs.push_back(R);
919 }
920
921 if (Qs.size() == 1) {
922 Quotient = Qs[0];
923 Remainder = Rs[0];
924 return;
925 }
926
927 Quotient = SE.getAddExpr(Qs);
928 Remainder = SE.getAddExpr(Rs);
929 }
930
931 void visitMulExpr(const SCEVMulExpr *Numerator) {
932 SmallVector<const SCEV *, 2> Qs;
933 Type *Ty = Denominator->getType();
934
935 bool FoundDenominatorTerm = false;
936 for (const SCEV *Op : Numerator->operands()) {
937 // Bail out if types do not match.
938 if (Ty != Op->getType())
939 return cannotDivide(Numerator);
940
941 if (FoundDenominatorTerm) {
942 Qs.push_back(Op);
943 continue;
944 }
945
946 // Check whether Denominator divides one of the product operands.
947 const SCEV *Q, *R;
948 divide(SE, Op, Denominator, &Q, &R);
949 if (!R->isZero()) {
950 Qs.push_back(Op);
951 continue;
952 }
953
954 // Bail out if types do not match.
955 if (Ty != Q->getType())
956 return cannotDivide(Numerator);
957
958 FoundDenominatorTerm = true;
959 Qs.push_back(Q);
960 }
961
962 if (FoundDenominatorTerm) {
963 Remainder = Zero;
964 if (Qs.size() == 1)
965 Quotient = Qs[0];
966 else
967 Quotient = SE.getMulExpr(Qs);
968 return;
969 }
970
971 if (!isa<SCEVUnknown>(Denominator))
972 return cannotDivide(Numerator);
973
974 // The Remainder is obtained by replacing Denominator by 0 in Numerator.
975 ValueToValueMap RewriteMap;
976 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
977 cast<SCEVConstant>(Zero)->getValue();
978 Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
979
980 if (Remainder->isZero()) {
981 // The Quotient is obtained by replacing Denominator by 1 in Numerator.
982 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
983 cast<SCEVConstant>(One)->getValue();
984 Quotient =
985 SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
986 return;
987 }
988
989 // Quotient is (Numerator - Remainder) divided by Denominator.
990 const SCEV *Q, *R;
991 const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder);
992 // This SCEV does not seem to simplify: fail the division here.
993 if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator))
994 return cannotDivide(Numerator);
995 divide(SE, Diff, Denominator, &Q, &R);
996 if (R != Zero)
997 return cannotDivide(Numerator);
998 Quotient = Q;
999 }
1000
1001private:
1002 SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
1003 const SCEV *Denominator)
1004 : SE(S), Denominator(Denominator) {
1005 Zero = SE.getZero(Denominator->getType());
1006 One = SE.getOne(Denominator->getType());
1007
1008 // We generally do not know how to divide Expr by Denominator. We
1009 // initialize the division to a "cannot divide" state to simplify the rest
1010 // of the code.
1011 cannotDivide(Numerator);
1012 }
1013
1014 // Convenience function for giving up on the division. We set the quotient to
1015 // be equal to zero and the remainder to be equal to the numerator.
1016 void cannotDivide(const SCEV *Numerator) {
1017 Quotient = Zero;
1018 Remainder = Numerator;
1019 }
1020
1021 ScalarEvolution &SE;
1022 const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
1023};
1024
1025}
1026
1027//===----------------------------------------------------------------------===//
1028// Simple SCEV method implementations
1029//===----------------------------------------------------------------------===//
1030
1031/// Compute BC(It, K). The result has width W. Assume, K > 0.
1032static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
1033 ScalarEvolution &SE,
1034 Type *ResultTy) {
1035 // Handle the simplest case efficiently.
1036 if (K == 1)
1037 return SE.getTruncateOrZeroExtend(It, ResultTy);
1038
1039 // We are using the following formula for BC(It, K):
1040 //
1041 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
1042 //
1043 // Suppose, W is the bitwidth of the return value. We must be prepared for
1044 // overflow. Hence, we must assure that the result of our computation is
1045 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
1046 // safe in modular arithmetic.
1047 //
1048 // However, this code doesn't use exactly that formula; the formula it uses
1049 // is something like the following, where T is the number of factors of 2 in
1050 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
1051 // exponentiation:
1052 //
1053 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
1054 //
1055 // This formula is trivially equivalent to the previous formula. However,
1056 // this formula can be implemented much more efficiently. The trick is that
1057 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
1058 // arithmetic. To do exact division in modular arithmetic, all we have
1059 // to do is multiply by the inverse. Therefore, this step can be done at
1060 // width W.
1061 //
1062 // The next issue is how to safely do the division by 2^T. The way this
1063 // is done is by doing the multiplication step at a width of at least W + T
1064 // bits. This way, the bottom W+T bits of the product are accurate. Then,
1065 // when we perform the division by 2^T (which is equivalent to a right shift
1066 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
1067 // truncated out after the division by 2^T.
1068 //
1069 // In comparison to just directly using the first formula, this technique
1070 // is much more efficient; using the first formula requires W * K bits,
1071 // but this formula less than W + K bits. Also, the first formula requires
1072 // a division step, whereas this formula only requires multiplies and shifts.
1073 //
1074 // It doesn't matter whether the subtraction step is done in the calculation
1075 // width or the input iteration count's width; if the subtraction overflows,
1076 // the result must be zero anyway. We prefer here to do it in the width of
1077 // the induction variable because it helps a lot for certain cases; CodeGen
1078 // isn't smart enough to ignore the overflow, which leads to much less
1079 // efficient code if the width of the subtraction is wider than the native
1080 // register width.
1081 //
1082 // (It's possible to not widen at all by pulling out factors of 2 before
1083 // the multiplication; for example, K=2 can be calculated as
1084 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
1085 // extra arithmetic, so it's not an obvious win, and it gets
1086 // much more complicated for K > 3.)
1087
1088 // Protection from insane SCEVs; this bound is conservative,
1089 // but it probably doesn't matter.
1090 if (K > 1000)
1091 return SE.getCouldNotCompute();
1092
1093 unsigned W = SE.getTypeSizeInBits(ResultTy);
1094
1095 // Calculate K! / 2^T and T; we divide out the factors of two before
1096 // multiplying for calculating K! / 2^T to avoid overflow.
1097 // Other overflow doesn't matter because we only care about the bottom
1098 // W bits of the result.
1099 APInt OddFactorial(W, 1);
1100 unsigned T = 1;
1101 for (unsigned i = 3; i <= K; ++i) {
1102 APInt Mult(W, i);
1103 unsigned TwoFactors = Mult.countTrailingZeros();
1104 T += TwoFactors;
1105 Mult.lshrInPlace(TwoFactors);
1106 OddFactorial *= Mult;
1107 }
1108
1109 // We need at least W + T bits for the multiplication step
1110 unsigned CalculationBits = W + T;
1111
1112 // Calculate 2^T, at width T+W.
1113 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1114
1115 // Calculate the multiplicative inverse of K! / 2^T;
1116 // this multiplication factor will perform the exact division by
1117 // K! / 2^T.
1118 APInt Mod = APInt::getSignedMinValue(W+1);
1119 APInt MultiplyFactor = OddFactorial.zext(W+1);
1120 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1121 MultiplyFactor = MultiplyFactor.trunc(W);
1122
1123 // Calculate the product, at width T+W
1124 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1125 CalculationBits);
1126 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1127 for (unsigned i = 1; i != K; ++i) {
1128 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1129 Dividend = SE.getMulExpr(Dividend,
1130 SE.getTruncateOrZeroExtend(S, CalculationTy));
1131 }
1132
1133 // Divide by 2^T
1134 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1135
1136 // Truncate the result, and divide by K! / 2^T.
1137
1138 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1139 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1140}
1141
1142/// Return the value of this chain of recurrences at the specified iteration
1143/// number. We can evaluate this recurrence by multiplying each element in the
1144/// chain by the binomial coefficient corresponding to it. In other words, we
1145/// can evaluate {A,+,B,+,C,+,D} as:
1146///
1147/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1148///
1149/// where BC(It, k) stands for binomial coefficient.
1150///
1151const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1152 ScalarEvolution &SE) const {
1153 const SCEV *Result = getStart();
1154 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1155 // The computation is correct in the face of overflow provided that the
1156 // multiplication is performed _after_ the evaluation of the binomial
1157 // coefficient.
1158 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1159 if (isa<SCEVCouldNotCompute>(Coeff))
1160 return Coeff;
1161
1162 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1163 }
1164 return Result;
1165}
1166
1167//===----------------------------------------------------------------------===//
1168// SCEV Expression folder implementations
1169//===----------------------------------------------------------------------===//
1170
1171const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
1172 Type *Ty) {
1173 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1174, __PRETTY_FUNCTION__))
1174 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1174, __PRETTY_FUNCTION__))
;
1175 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1176, __PRETTY_FUNCTION__))
1176 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1176, __PRETTY_FUNCTION__))
;
1177 Ty = getEffectiveSCEVType(Ty);
1178
1179 FoldingSetNodeID ID;
1180 ID.AddInteger(scTruncate);
1181 ID.AddPointer(Op);
1182 ID.AddPointer(Ty);
1183 void *IP = nullptr;
1184 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1185
1186 // Fold if the operand is constant.
1187 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1188 return getConstant(
1189 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1190
1191 // trunc(trunc(x)) --> trunc(x)
1192 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1193 return getTruncateExpr(ST->getOperand(), Ty);
1194
1195 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1196 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1197 return getTruncateOrSignExtend(SS->getOperand(), Ty);
1198
1199 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1200 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1201 return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
1202
1203 // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can
1204 // eliminate all the truncates, or we replace other casts with truncates.
1205 if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) {
1206 SmallVector<const SCEV *, 4> Operands;
1207 bool hasTrunc = false;
1208 for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) {
1209 const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty);
1210 if (!isa<SCEVCastExpr>(SA->getOperand(i)))
1211 hasTrunc = isa<SCEVTruncateExpr>(S);
1212 Operands.push_back(S);
1213 }
1214 if (!hasTrunc)
1215 return getAddExpr(Operands);
1216 UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
1217 }
1218
1219 // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
1220 // eliminate all the truncates, or we replace other casts with truncates.
1221 if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
1222 SmallVector<const SCEV *, 4> Operands;
1223 bool hasTrunc = false;
1224 for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
1225 const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
1226 if (!isa<SCEVCastExpr>(SM->getOperand(i)))
1227 hasTrunc = isa<SCEVTruncateExpr>(S);
1228 Operands.push_back(S);
1229 }
1230 if (!hasTrunc)
1231 return getMulExpr(Operands);
1232 UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
1233 }
1234
1235 // If the input value is a chrec scev, truncate the chrec's operands.
1236 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1237 SmallVector<const SCEV *, 4> Operands;
1238 for (const SCEV *Op : AddRec->operands())
1239 Operands.push_back(getTruncateExpr(Op, Ty));
1240 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1241 }
1242
1243 // The cast wasn't folded; create an explicit cast node. We can reuse
1244 // the existing insert position since if we get here, we won't have
1245 // made any changes which would invalidate it.
1246 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1247 Op, Ty);
1248 UniqueSCEVs.InsertNode(S, IP);
1249 return S;
1250}
1251
1252// Get the limit of a recurrence such that incrementing by Step cannot cause
1253// signed overflow as long as the value of the recurrence within the
1254// loop does not exceed this limit before incrementing.
1255static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1256 ICmpInst::Predicate *Pred,
1257 ScalarEvolution *SE) {
1258 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1259 if (SE->isKnownPositive(Step)) {
1260 *Pred = ICmpInst::ICMP_SLT;
1261 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1262 SE->getSignedRangeMax(Step));
1263 }
1264 if (SE->isKnownNegative(Step)) {
1265 *Pred = ICmpInst::ICMP_SGT;
1266 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1267 SE->getSignedRangeMin(Step));
1268 }
1269 return nullptr;
1270}
1271
1272// Get the limit of a recurrence such that incrementing by Step cannot cause
1273// unsigned overflow as long as the value of the recurrence within the loop does
1274// not exceed this limit before incrementing.
1275static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1276 ICmpInst::Predicate *Pred,
1277 ScalarEvolution *SE) {
1278 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1279 *Pred = ICmpInst::ICMP_ULT;
1280
1281 return SE->getConstant(APInt::getMinValue(BitWidth) -
1282 SE->getUnsignedRangeMax(Step));
1283}
1284
1285namespace {
1286
1287struct ExtendOpTraitsBase {
1288 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(
1289 const SCEV *, Type *, ScalarEvolution::ExtendCacheTy &Cache);
1290};
1291
1292// Used to make code generic over signed and unsigned overflow.
1293template <typename ExtendOp> struct ExtendOpTraits {
1294 // Members present:
1295 //
1296 // static const SCEV::NoWrapFlags WrapType;
1297 //
1298 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1299 //
1300 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1301 // ICmpInst::Predicate *Pred,
1302 // ScalarEvolution *SE);
1303};
1304
1305template <>
1306struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1307 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1308
1309 static const GetExtendExprTy GetExtendExpr;
1310
1311 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1312 ICmpInst::Predicate *Pred,
1313 ScalarEvolution *SE) {
1314 return getSignedOverflowLimitForStep(Step, Pred, SE);
1315 }
1316};
1317
1318const ExtendOpTraitsBase::GetExtendExprTy
1319 ExtendOpTraits<SCEVSignExtendExpr>::GetExtendExpr =
1320 &ScalarEvolution::getSignExtendExprCached;
1321
1322template <>
1323struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1324 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1325
1326 static const GetExtendExprTy GetExtendExpr;
1327
1328 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1329 ICmpInst::Predicate *Pred,
1330 ScalarEvolution *SE) {
1331 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1332 }
1333};
1334
1335const ExtendOpTraitsBase::GetExtendExprTy
1336 ExtendOpTraits<SCEVZeroExtendExpr>::GetExtendExpr =
1337 &ScalarEvolution::getZeroExtendExprCached;
1338}
1339
1340// The recurrence AR has been shown to have no signed/unsigned wrap or something
1341// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1342// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1343// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1344// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1345// expression "Step + sext/zext(PreIncAR)" is congruent with
1346// "sext/zext(PostIncAR)"
1347template <typename ExtendOpTy>
1348static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1349 ScalarEvolution *SE,
1350 ScalarEvolution::ExtendCacheTy &Cache) {
1351 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1352 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1353
1354 const Loop *L = AR->getLoop();
1355 const SCEV *Start = AR->getStart();
1356 const SCEV *Step = AR->getStepRecurrence(*SE);
1357
1358 // Check for a simple looking step prior to loop entry.
1359 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1360 if (!SA)
1361 return nullptr;
1362
1363 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1364 // subtraction is expensive. For this purpose, perform a quick and dirty
1365 // difference, by checking for Step in the operand list.
1366 SmallVector<const SCEV *, 4> DiffOps;
1367 for (const SCEV *Op : SA->operands())
1368 if (Op != Step)
1369 DiffOps.push_back(Op);
1370
1371 if (DiffOps.size() == SA->getNumOperands())
1372 return nullptr;
1373
1374 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1375 // `Step`:
1376
1377 // 1. NSW/NUW flags on the step increment.
1378 auto PreStartFlags =
1379 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1380 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1381 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1382 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1383
1384 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1385 // "S+X does not sign/unsign-overflow".
1386 //
1387
1388 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1389 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1390 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1391 return PreStart;
1392
1393 // 2. Direct overflow check on the step operation's expression.
1394 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1395 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1396 const SCEV *OperandExtendedStart =
1397 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Cache),
1398 (SE->*GetExtendExpr)(Step, WideTy, Cache));
1399 if ((SE->*GetExtendExpr)(Start, WideTy, Cache) == OperandExtendedStart) {
1400 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1401 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1402 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1403 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1404 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1405 }
1406 return PreStart;
1407 }
1408
1409 // 3. Loop precondition.
1410 ICmpInst::Predicate Pred;
1411 const SCEV *OverflowLimit =
1412 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1413
1414 if (OverflowLimit &&
1415 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1416 return PreStart;
1417
1418 return nullptr;
1419}
1420
1421// Get the normalized zero or sign extended expression for this AddRec's Start.
1422template <typename ExtendOpTy>
1423static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1424 ScalarEvolution *SE,
1425 ScalarEvolution::ExtendCacheTy &Cache) {
1426 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1427
1428 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Cache);
1429 if (!PreStart)
1430 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Cache);
1431
1432 return SE->getAddExpr(
1433 (SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty, Cache),
1434 (SE->*GetExtendExpr)(PreStart, Ty, Cache));
1435}
1436
1437// Try to prove away overflow by looking at "nearby" add recurrences. A
1438// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1439// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1440//
1441// Formally:
1442//
1443// {S,+,X} == {S-T,+,X} + T
1444// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1445//
1446// If ({S-T,+,X} + T) does not overflow ... (1)
1447//
1448// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1449//
1450// If {S-T,+,X} does not overflow ... (2)
1451//
1452// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1453// == {Ext(S-T)+Ext(T),+,Ext(X)}
1454//
1455// If (S-T)+T does not overflow ... (3)
1456//
1457// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1458// == {Ext(S),+,Ext(X)} == LHS
1459//
1460// Thus, if (1), (2) and (3) are true for some T, then
1461// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1462//
1463// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1464// does not overflow" restricted to the 0th iteration. Therefore we only need
1465// to check for (1) and (2).
1466//
1467// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1468// is `Delta` (defined below).
1469//
1470template <typename ExtendOpTy>
1471bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1472 const SCEV *Step,
1473 const Loop *L) {
1474 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1475
1476 // We restrict `Start` to a constant to prevent SCEV from spending too much
1477 // time here. It is correct (but more expensive) to continue with a
1478 // non-constant `Start` and do a general SCEV subtraction to compute
1479 // `PreStart` below.
1480 //
1481 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1482 if (!StartC)
1483 return false;
1484
1485 APInt StartAI = StartC->getAPInt();
1486
1487 for (unsigned Delta : {-2, -1, 1, 2}) {
1488 const SCEV *PreStart = getConstant(StartAI - Delta);
1489
1490 FoldingSetNodeID ID;
1491 ID.AddInteger(scAddRecExpr);
1492 ID.AddPointer(PreStart);
1493 ID.AddPointer(Step);
1494 ID.AddPointer(L);
1495 void *IP = nullptr;
1496 const auto *PreAR =
1497 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1498
1499 // Give up if we don't already have the add recurrence we need because
1500 // actually constructing an add recurrence is relatively expensive.
1501 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1502 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1503 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1504 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1505 DeltaS, &Pred, this);
1506 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1507 return true;
1508 }
1509 }
1510
1511 return false;
1512}
1513
1514const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty) {
1515 // Use the local cache to prevent exponential behavior of
1516 // getZeroExtendExprImpl.
1517 ExtendCacheTy Cache;
1518 return getZeroExtendExprCached(Op, Ty, Cache);
1519}
1520
1521/// Query \p Cache before calling getZeroExtendExprImpl. If there is no
1522/// related entry in the \p Cache, call getZeroExtendExprImpl and save
1523/// the result in the \p Cache.
1524const SCEV *ScalarEvolution::getZeroExtendExprCached(const SCEV *Op, Type *Ty,
1525 ExtendCacheTy &Cache) {
1526 auto It = Cache.find({Op, Ty});
1527 if (It != Cache.end())
1528 return It->second;
1529 const SCEV *ZExt = getZeroExtendExprImpl(Op, Ty, Cache);
1530 auto InsertResult = Cache.insert({{Op, Ty}, ZExt});
1531 assert(InsertResult.second && "Expect the key was not in the cache")((InsertResult.second && "Expect the key was not in the cache"
) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expect the key was not in the cache\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1531, __PRETTY_FUNCTION__))
;
1532 (void)InsertResult;
1533 return ZExt;
1534}
1535
1536/// The real implementation of getZeroExtendExpr.
1537const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
1538 ExtendCacheTy &Cache) {
1539 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1540, __PRETTY_FUNCTION__))
1540 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1540, __PRETTY_FUNCTION__))
;
1541 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1542, __PRETTY_FUNCTION__))
1542 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1542, __PRETTY_FUNCTION__))
;
1543 Ty = getEffectiveSCEVType(Ty);
1544
1545 // Fold if the operand is constant.
1546 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1547 return getConstant(
1548 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1549
1550 // zext(zext(x)) --> zext(x)
1551 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1552 return getZeroExtendExprCached(SZ->getOperand(), Ty, Cache);
1553
1554 // Before doing any expensive analysis, check to see if we've already
1555 // computed a SCEV for this Op and Ty.
1556 FoldingSetNodeID ID;
1557 ID.AddInteger(scZeroExtend);
1558 ID.AddPointer(Op);
1559 ID.AddPointer(Ty);
1560 void *IP = nullptr;
1561 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1562
1563 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1564 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1565 // It's possible the bits taken off by the truncate were all zero bits. If
1566 // so, we should be able to simplify this further.
1567 const SCEV *X = ST->getOperand();
1568 ConstantRange CR = getUnsignedRange(X);
1569 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1570 unsigned NewBits = getTypeSizeInBits(Ty);
1571 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1572 CR.zextOrTrunc(NewBits)))
1573 return getTruncateOrZeroExtend(X, Ty);
1574 }
1575
1576 // If the input value is a chrec scev, and we can prove that the value
1577 // did not overflow the old, smaller, value, we can zero extend all of the
1578 // operands (often constants). This allows analysis of something like
1579 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1580 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1581 if (AR->isAffine()) {
1582 const SCEV *Start = AR->getStart();
1583 const SCEV *Step = AR->getStepRecurrence(*this);
1584 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1585 const Loop *L = AR->getLoop();
1586
1587 if (!AR->hasNoUnsignedWrap()) {
1588 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1589 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1590 }
1591
1592 // If we have special knowledge that this addrec won't overflow,
1593 // we don't need to do any further analysis.
1594 if (AR->hasNoUnsignedWrap())
1595 return getAddRecExpr(
1596 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
1597 getZeroExtendExprCached(Step, Ty, Cache), L, AR->getNoWrapFlags());
1598
1599 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1600 // Note that this serves two purposes: It filters out loops that are
1601 // simply not analyzable, and it covers the case where this code is
1602 // being called from within backedge-taken count analysis, such that
1603 // attempting to ask for the backedge-taken count would likely result
1604 // in infinite recursion. In the later case, the analysis code will
1605 // cope with a conservative value, and it will take care to purge
1606 // that value once it has finished.
1607 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1608 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1609 // Manually compute the final value for AR, checking for
1610 // overflow.
1611
1612 // Check whether the backedge-taken count can be losslessly casted to
1613 // the addrec's type. The count is always unsigned.
1614 const SCEV *CastedMaxBECount =
1615 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1616 const SCEV *RecastedMaxBECount =
1617 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1618 if (MaxBECount == RecastedMaxBECount) {
1619 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1620 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1621 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step);
1622 const SCEV *ZAdd =
1623 getZeroExtendExprCached(getAddExpr(Start, ZMul), WideTy, Cache);
1624 const SCEV *WideStart = getZeroExtendExprCached(Start, WideTy, Cache);
1625 const SCEV *WideMaxBECount =
1626 getZeroExtendExprCached(CastedMaxBECount, WideTy, Cache);
1627 const SCEV *OperandExtendedAdd = getAddExpr(
1628 WideStart, getMulExpr(WideMaxBECount, getZeroExtendExprCached(
1629 Step, WideTy, Cache)));
1630 if (ZAdd == OperandExtendedAdd) {
1631 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1632 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1633 // Return the expression with the addrec on the outside.
1634 return getAddRecExpr(
1635 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
1636 getZeroExtendExprCached(Step, Ty, Cache), L,
1637 AR->getNoWrapFlags());
1638 }
1639 // Similar to above, only this time treat the step value as signed.
1640 // This covers loops that count down.
1641 OperandExtendedAdd =
1642 getAddExpr(WideStart,
1643 getMulExpr(WideMaxBECount,
1644 getSignExtendExpr(Step, WideTy)));
1645 if (ZAdd == OperandExtendedAdd) {
1646 // Cache knowledge of AR NW, which is propagated to this AddRec.
1647 // Negative step causes unsigned wrap, but it still can't self-wrap.
1648 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1649 // Return the expression with the addrec on the outside.
1650 return getAddRecExpr(
1651 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
1652 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1653 }
1654 }
1655 }
1656
1657 // Normally, in the cases we can prove no-overflow via a
1658 // backedge guarding condition, we can also compute a backedge
1659 // taken count for the loop. The exceptions are assumptions and
1660 // guards present in the loop -- SCEV is not great at exploiting
1661 // these to compute max backedge taken counts, but can still use
1662 // these to prove lack of overflow. Use this fact to avoid
1663 // doing extra work that may not pay off.
1664 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1665 !AC.assumptions().empty()) {
1666 // If the backedge is guarded by a comparison with the pre-inc
1667 // value the addrec is safe. Also, if the entry is guarded by
1668 // a comparison with the start value and the backedge is
1669 // guarded by a comparison with the post-inc value, the addrec
1670 // is safe.
1671 if (isKnownPositive(Step)) {
1672 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1673 getUnsignedRangeMax(Step));
1674 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1675 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
1676 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
1677 AR->getPostIncExpr(*this), N))) {
1678 // Cache knowledge of AR NUW, which is propagated to this
1679 // AddRec.
1680 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1681 // Return the expression with the addrec on the outside.
1682 return getAddRecExpr(
1683 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
1684 getZeroExtendExprCached(Step, Ty, Cache), L,
1685 AR->getNoWrapFlags());
1686 }
1687 } else if (isKnownNegative(Step)) {
1688 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1689 getSignedRangeMin(Step));
1690 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1691 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) &&
1692 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
1693 AR->getPostIncExpr(*this), N))) {
1694 // Cache knowledge of AR NW, which is propagated to this
1695 // AddRec. Negative step causes unsigned wrap, but it
1696 // still can't self-wrap.
1697 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1698 // Return the expression with the addrec on the outside.
1699 return getAddRecExpr(
1700 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
1701 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1702 }
1703 }
1704 }
1705
1706 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1707 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1708 return getAddRecExpr(
1709 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Cache),
1710 getZeroExtendExprCached(Step, Ty, Cache), L, AR->getNoWrapFlags());
1711 }
1712 }
1713
1714 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1715 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1716 if (SA->hasNoUnsignedWrap()) {
1717 // If the addition does not unsign overflow then we can, by definition,
1718 // commute the zero extension with the addition operation.
1719 SmallVector<const SCEV *, 4> Ops;
1720 for (const auto *Op : SA->operands())
1721 Ops.push_back(getZeroExtendExprCached(Op, Ty, Cache));
1722 return getAddExpr(Ops, SCEV::FlagNUW);
1723 }
1724 }
1725
1726 // The cast wasn't folded; create an explicit cast node.
1727 // Recompute the insert position, as it may have been invalidated.
1728 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1729 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1730 Op, Ty);
1731 UniqueSCEVs.InsertNode(S, IP);
1732 return S;
1733}
1734
1735const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty) {
1736 // Use the local cache to prevent exponential behavior of
1737 // getSignExtendExprImpl.
1738 ExtendCacheTy Cache;
1739 return getSignExtendExprCached(Op, Ty, Cache);
1740}
1741
1742/// Query \p Cache before calling getSignExtendExprImpl. If there is no
1743/// related entry in the \p Cache, call getSignExtendExprImpl and save
1744/// the result in the \p Cache.
1745const SCEV *ScalarEvolution::getSignExtendExprCached(const SCEV *Op, Type *Ty,
1746 ExtendCacheTy &Cache) {
1747 auto It = Cache.find({Op, Ty});
1748 if (It != Cache.end())
1749 return It->second;
1750 const SCEV *SExt = getSignExtendExprImpl(Op, Ty, Cache);
1751 auto InsertResult = Cache.insert({{Op, Ty}, SExt});
1752 assert(InsertResult.second && "Expect the key was not in the cache")((InsertResult.second && "Expect the key was not in the cache"
) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expect the key was not in the cache\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1752, __PRETTY_FUNCTION__))
;
1753 (void)InsertResult;
1754 return SExt;
1755}
1756
1757/// The real implementation of getSignExtendExpr.
1758const SCEV *ScalarEvolution::getSignExtendExprImpl(const SCEV *Op, Type *Ty,
1759 ExtendCacheTy &Cache) {
1760 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1761, __PRETTY_FUNCTION__))
1761 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1761, __PRETTY_FUNCTION__))
;
1762 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1763, __PRETTY_FUNCTION__))
1763 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1763, __PRETTY_FUNCTION__))
;
1764 Ty = getEffectiveSCEVType(Ty);
1765
1766 // Fold if the operand is constant.
1767 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1768 return getConstant(
1769 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1770
1771 // sext(sext(x)) --> sext(x)
1772 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1773 return getSignExtendExprCached(SS->getOperand(), Ty, Cache);
1774
1775 // sext(zext(x)) --> zext(x)
1776 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1777 return getZeroExtendExpr(SZ->getOperand(), Ty);
1778
1779 // Before doing any expensive analysis, check to see if we've already
1780 // computed a SCEV for this Op and Ty.
1781 FoldingSetNodeID ID;
1782 ID.AddInteger(scSignExtend);
1783 ID.AddPointer(Op);
1784 ID.AddPointer(Ty);
1785 void *IP = nullptr;
1786 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1787
1788 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1789 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1790 // It's possible the bits taken off by the truncate were all sign bits. If
1791 // so, we should be able to simplify this further.
1792 const SCEV *X = ST->getOperand();
1793 ConstantRange CR = getSignedRange(X);
1794 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1795 unsigned NewBits = getTypeSizeInBits(Ty);
1796 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1797 CR.sextOrTrunc(NewBits)))
1798 return getTruncateOrSignExtend(X, Ty);
1799 }
1800
1801 // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2
1802 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1803 if (SA->getNumOperands() == 2) {
1804 auto *SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0));
1805 auto *SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1));
1806 if (SMul && SC1) {
1807 if (auto *SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) {
1808 const APInt &C1 = SC1->getAPInt();
1809 const APInt &C2 = SC2->getAPInt();
1810 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
1811 C2.ugt(C1) && C2.isPowerOf2())
1812 return getAddExpr(getSignExtendExprCached(SC1, Ty, Cache),
1813 getSignExtendExprCached(SMul, Ty, Cache));
1814 }
1815 }
1816 }
1817
1818 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1819 if (SA->hasNoSignedWrap()) {
1820 // If the addition does not sign overflow then we can, by definition,
1821 // commute the sign extension with the addition operation.
1822 SmallVector<const SCEV *, 4> Ops;
1823 for (const auto *Op : SA->operands())
1824 Ops.push_back(getSignExtendExprCached(Op, Ty, Cache));
1825 return getAddExpr(Ops, SCEV::FlagNSW);
1826 }
1827 }
1828 // If the input value is a chrec scev, and we can prove that the value
1829 // did not overflow the old, smaller, value, we can sign extend all of the
1830 // operands (often constants). This allows analysis of something like
1831 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1832 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1833 if (AR->isAffine()) {
1834 const SCEV *Start = AR->getStart();
1835 const SCEV *Step = AR->getStepRecurrence(*this);
1836 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1837 const Loop *L = AR->getLoop();
1838
1839 if (!AR->hasNoSignedWrap()) {
1840 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1841 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1842 }
1843
1844 // If we have special knowledge that this addrec won't overflow,
1845 // we don't need to do any further analysis.
1846 if (AR->hasNoSignedWrap())
1847 return getAddRecExpr(
1848 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
1849 getSignExtendExprCached(Step, Ty, Cache), L, SCEV::FlagNSW);
1850
1851 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1852 // Note that this serves two purposes: It filters out loops that are
1853 // simply not analyzable, and it covers the case where this code is
1854 // being called from within backedge-taken count analysis, such that
1855 // attempting to ask for the backedge-taken count would likely result
1856 // in infinite recursion. In the later case, the analysis code will
1857 // cope with a conservative value, and it will take care to purge
1858 // that value once it has finished.
1859 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1860 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1861 // Manually compute the final value for AR, checking for
1862 // overflow.
1863
1864 // Check whether the backedge-taken count can be losslessly casted to
1865 // the addrec's type. The count is always unsigned.
1866 const SCEV *CastedMaxBECount =
1867 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1868 const SCEV *RecastedMaxBECount =
1869 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1870 if (MaxBECount == RecastedMaxBECount) {
1871 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1872 // Check whether Start+Step*MaxBECount has no signed overflow.
1873 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
1874 const SCEV *SAdd =
1875 getSignExtendExprCached(getAddExpr(Start, SMul), WideTy, Cache);
1876 const SCEV *WideStart = getSignExtendExprCached(Start, WideTy, Cache);
1877 const SCEV *WideMaxBECount =
1878 getZeroExtendExpr(CastedMaxBECount, WideTy);
1879 const SCEV *OperandExtendedAdd = getAddExpr(
1880 WideStart, getMulExpr(WideMaxBECount, getSignExtendExprCached(
1881 Step, WideTy, Cache)));
1882 if (SAdd == OperandExtendedAdd) {
1883 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1884 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1885 // Return the expression with the addrec on the outside.
1886 return getAddRecExpr(
1887 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
1888 getSignExtendExprCached(Step, Ty, Cache), L,
1889 AR->getNoWrapFlags());
1890 }
1891 // Similar to above, only this time treat the step value as unsigned.
1892 // This covers loops that count up with an unsigned step.
1893 OperandExtendedAdd =
1894 getAddExpr(WideStart,
1895 getMulExpr(WideMaxBECount,
1896 getZeroExtendExpr(Step, WideTy)));
1897 if (SAdd == OperandExtendedAdd) {
1898 // If AR wraps around then
1899 //
1900 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
1901 // => SAdd != OperandExtendedAdd
1902 //
1903 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
1904 // (SAdd == OperandExtendedAdd => AR is NW)
1905
1906 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1907
1908 // Return the expression with the addrec on the outside.
1909 return getAddRecExpr(
1910 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
1911 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1912 }
1913 }
1914 }
1915
1916 // Normally, in the cases we can prove no-overflow via a
1917 // backedge guarding condition, we can also compute a backedge
1918 // taken count for the loop. The exceptions are assumptions and
1919 // guards present in the loop -- SCEV is not great at exploiting
1920 // these to compute max backedge taken counts, but can still use
1921 // these to prove lack of overflow. Use this fact to avoid
1922 // doing extra work that may not pay off.
1923
1924 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1925 !AC.assumptions().empty()) {
1926 // If the backedge is guarded by a comparison with the pre-inc
1927 // value the addrec is safe. Also, if the entry is guarded by
1928 // a comparison with the start value and the backedge is
1929 // guarded by a comparison with the post-inc value, the addrec
1930 // is safe.
1931 ICmpInst::Predicate Pred;
1932 const SCEV *OverflowLimit =
1933 getSignedOverflowLimitForStep(Step, &Pred, this);
1934 if (OverflowLimit &&
1935 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
1936 (isLoopEntryGuardedByCond(L, Pred, Start, OverflowLimit) &&
1937 isLoopBackedgeGuardedByCond(L, Pred, AR->getPostIncExpr(*this),
1938 OverflowLimit)))) {
1939 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
1940 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1941 return getAddRecExpr(
1942 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
1943 getSignExtendExprCached(Step, Ty, Cache), L,
1944 AR->getNoWrapFlags());
1945 }
1946 }
1947
1948 // If Start and Step are constants, check if we can apply this
1949 // transformation:
1950 // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2
1951 auto *SC1 = dyn_cast<SCEVConstant>(Start);
1952 auto *SC2 = dyn_cast<SCEVConstant>(Step);
1953 if (SC1 && SC2) {
1954 const APInt &C1 = SC1->getAPInt();
1955 const APInt &C2 = SC2->getAPInt();
1956 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) &&
1957 C2.isPowerOf2()) {
1958 Start = getSignExtendExprCached(Start, Ty, Cache);
1959 const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L,
1960 AR->getNoWrapFlags());
1961 return getAddExpr(Start, getSignExtendExprCached(NewAR, Ty, Cache));
1962 }
1963 }
1964
1965 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
1966 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1967 return getAddRecExpr(
1968 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Cache),
1969 getSignExtendExprCached(Step, Ty, Cache), L, AR->getNoWrapFlags());
1970 }
1971 }
1972
1973 // If the input value is provably positive and we could not simplify
1974 // away the sext build a zext instead.
1975 if (isKnownNonNegative(Op))
1976 return getZeroExtendExpr(Op, Ty);
1977
1978 // The cast wasn't folded; create an explicit cast node.
1979 // Recompute the insert position, as it may have been invalidated.
1980 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1981 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1982 Op, Ty);
1983 UniqueSCEVs.InsertNode(S, IP);
1984 return S;
1985}
1986
1987/// getAnyExtendExpr - Return a SCEV for the given operand extended with
1988/// unspecified bits out to the given type.
1989///
1990const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
1991 Type *Ty) {
1992 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1993, __PRETTY_FUNCTION__))
1993 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1993, __PRETTY_FUNCTION__))
;
1994 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1995, __PRETTY_FUNCTION__))
1995 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 1995, __PRETTY_FUNCTION__))
;
1996 Ty = getEffectiveSCEVType(Ty);
1997
1998 // Sign-extend negative constants.
1999 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2000 if (SC->getAPInt().isNegative())
2001 return getSignExtendExpr(Op, Ty);
2002
2003 // Peel off a truncate cast.
2004 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2005 const SCEV *NewOp = T->getOperand();
2006 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2007 return getAnyExtendExpr(NewOp, Ty);
2008 return getTruncateOrNoop(NewOp, Ty);
2009 }
2010
2011 // Next try a zext cast. If the cast is folded, use it.
2012 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2013 if (!isa<SCEVZeroExtendExpr>(ZExt))
2014 return ZExt;
2015
2016 // Next try a sext cast. If the cast is folded, use it.
2017 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2018 if (!isa<SCEVSignExtendExpr>(SExt))
2019 return SExt;
2020
2021 // Force the cast to be folded into the operands of an addrec.
2022 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2023 SmallVector<const SCEV *, 4> Ops;
2024 for (const SCEV *Op : AR->operands())
2025 Ops.push_back(getAnyExtendExpr(Op, Ty));
2026 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2027 }
2028
2029 // If the expression is obviously signed, use the sext cast value.
2030 if (isa<SCEVSMaxExpr>(Op))
2031 return SExt;
2032
2033 // Absent any other information, use the zext cast value.
2034 return ZExt;
2035}
2036
2037/// Process the given Ops list, which is a list of operands to be added under
2038/// the given scale, update the given map. This is a helper function for
2039/// getAddRecExpr. As an example of what it does, given a sequence of operands
2040/// that would form an add expression like this:
2041///
2042/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2043///
2044/// where A and B are constants, update the map with these values:
2045///
2046/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2047///
2048/// and add 13 + A*B*29 to AccumulatedConstant.
2049/// This will allow getAddRecExpr to produce this:
2050///
2051/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2052///
2053/// This form often exposes folding opportunities that are hidden in
2054/// the original operand list.
2055///
2056/// Return true iff it appears that any interesting folding opportunities
2057/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2058/// the common case where no interesting opportunities are present, and
2059/// is also used as a check to avoid infinite recursion.
2060///
2061static bool
2062CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2063 SmallVectorImpl<const SCEV *> &NewOps,
2064 APInt &AccumulatedConstant,
2065 const SCEV *const *Ops, size_t NumOperands,
2066 const APInt &Scale,
2067 ScalarEvolution &SE) {
2068 bool Interesting = false;
2069
2070 // Iterate over the add operands. They are sorted, with constants first.
2071 unsigned i = 0;
2072 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2073 ++i;
2074 // Pull a buried constant out to the outside.
2075 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2076 Interesting = true;
2077 AccumulatedConstant += Scale * C->getAPInt();
2078 }
2079
2080 // Next comes everything else. We're especially interested in multiplies
2081 // here, but they're in the middle, so just visit the rest with one loop.
2082 for (; i != NumOperands; ++i) {
2083 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2084 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2085 APInt NewScale =
2086 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2087 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2088 // A multiplication of a constant with another add; recurse.
2089 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2090 Interesting |=
2091 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2092 Add->op_begin(), Add->getNumOperands(),
2093 NewScale, SE);
2094 } else {
2095 // A multiplication of a constant with some other value. Update
2096 // the map.
2097 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
2098 const SCEV *Key = SE.getMulExpr(MulOps);
2099 auto Pair = M.insert({Key, NewScale});
2100 if (Pair.second) {
2101 NewOps.push_back(Pair.first->first);
2102 } else {
2103 Pair.first->second += NewScale;
2104 // The map already had an entry for this value, which may indicate
2105 // a folding opportunity.
2106 Interesting = true;
2107 }
2108 }
2109 } else {
2110 // An ordinary operand. Update the map.
2111 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2112 M.insert({Ops[i], Scale});
2113 if (Pair.second) {
2114 NewOps.push_back(Pair.first->first);
2115 } else {
2116 Pair.first->second += Scale;
2117 // The map already had an entry for this value, which may indicate
2118 // a folding opportunity.
2119 Interesting = true;
2120 }
2121 }
2122 }
2123
2124 return Interesting;
2125}
2126
2127// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2128// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2129// can't-overflow flags for the operation if possible.
2130static SCEV::NoWrapFlags
2131StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2132 const SmallVectorImpl<const SCEV *> &Ops,
2133 SCEV::NoWrapFlags Flags) {
2134 using namespace std::placeholders;
2135 typedef OverflowingBinaryOperator OBO;
2136
2137 bool CanAnalyze =
2138 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2139 (void)CanAnalyze;
2140 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2140, __PRETTY_FUNCTION__))
;
2141
2142 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2143 SCEV::NoWrapFlags SignOrUnsignWrap =
2144 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2145
2146 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2147 auto IsKnownNonNegative = [&](const SCEV *S) {
2148 return SE->isKnownNonNegative(S);
2149 };
2150
2151 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2152 Flags =
2153 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2154
2155 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2156
2157 if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr &&
2158 Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) {
2159
2160 // (A + C) --> (A + C)<nsw> if the addition does not sign overflow
2161 // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow
2162
2163 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2164 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2165 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2166 Instruction::Add, C, OBO::NoSignedWrap);
2167 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2168 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2169 }
2170 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2171 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2172 Instruction::Add, C, OBO::NoUnsignedWrap);
2173 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2174 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2175 }
2176 }
2177
2178 return Flags;
2179}
2180
2181bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2182 if (!isLoopInvariant(S, L))
2183 return false;
2184 // If a value depends on a SCEVUnknown which is defined after the loop, we
2185 // conservatively assume that we cannot calculate it at the loop's entry.
2186 struct FindDominatedSCEVUnknown {
2187 bool Found = false;
2188 const Loop *L;
2189 DominatorTree &DT;
2190 LoopInfo &LI;
2191
2192 FindDominatedSCEVUnknown(const Loop *L, DominatorTree &DT, LoopInfo &LI)
2193 : L(L), DT(DT), LI(LI) {}
2194
2195 bool checkSCEVUnknown(const SCEVUnknown *SU) {
2196 if (auto *I = dyn_cast<Instruction>(SU->getValue())) {
2197 if (DT.dominates(L->getHeader(), I->getParent()))
2198 Found = true;
2199 else
2200 assert(DT.dominates(I->getParent(), L->getHeader()) &&((DT.dominates(I->getParent(), L->getHeader()) &&
"No dominance relationship between SCEV and loop?") ? static_cast
<void> (0) : __assert_fail ("DT.dominates(I->getParent(), L->getHeader()) && \"No dominance relationship between SCEV and loop?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2201, __PRETTY_FUNCTION__))
2201 "No dominance relationship between SCEV and loop?")((DT.dominates(I->getParent(), L->getHeader()) &&
"No dominance relationship between SCEV and loop?") ? static_cast
<void> (0) : __assert_fail ("DT.dominates(I->getParent(), L->getHeader()) && \"No dominance relationship between SCEV and loop?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2201, __PRETTY_FUNCTION__))
;
2202 }
2203 return false;
2204 }
2205
2206 bool follow(const SCEV *S) {
2207 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
2208 case scConstant:
2209 return false;
2210 case scAddRecExpr:
2211 case scTruncate:
2212 case scZeroExtend:
2213 case scSignExtend:
2214 case scAddExpr:
2215 case scMulExpr:
2216 case scUMaxExpr:
2217 case scSMaxExpr:
2218 case scUDivExpr:
2219 return true;
2220 case scUnknown:
2221 return checkSCEVUnknown(cast<SCEVUnknown>(S));
2222 case scCouldNotCompute:
2223 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2223)
;
2224 }
2225 return false;
2226 }
2227
2228 bool isDone() { return Found; }
2229 };
2230
2231 FindDominatedSCEVUnknown FSU(L, DT, LI);
2232 SCEVTraversal<FindDominatedSCEVUnknown> ST(FSU);
2233 ST.visitAll(S);
2234 return !FSU.Found;
2235}
2236
2237/// Get a canonical add expression, or something simpler if possible.
2238const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2239 SCEV::NoWrapFlags Flags,
2240 unsigned Depth) {
2241 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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2242, __PRETTY_FUNCTION__))
2242 "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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2242, __PRETTY_FUNCTION__))
;
2243 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2243, __PRETTY_FUNCTION__))
;
2244 if (Ops.size() == 1) return Ops[0];
2245#ifndef NDEBUG
2246 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2247 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2248 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2249, __PRETTY_FUNCTION__))
2249 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2249, __PRETTY_FUNCTION__))
;
2250#endif
2251
2252 // Sort by complexity, this groups all similar expression types together.
2253 GroupByComplexity(Ops, &LI, DT);
2254
2255 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2256
2257 // If there are any constants, fold them together.
2258 unsigned Idx = 0;
2259 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2260 ++Idx;
2261 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2261, __PRETTY_FUNCTION__))
;
2262 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2263 // We found two constants, fold them together!
2264 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2265 if (Ops.size() == 2) return Ops[0];
2266 Ops.erase(Ops.begin()+1); // Erase the folded element
2267 LHSC = cast<SCEVConstant>(Ops[0]);
2268 }
2269
2270 // If we are left with a constant zero being added, strip it off.
2271 if (LHSC->getValue()->isZero()) {
2272 Ops.erase(Ops.begin());
2273 --Idx;
2274 }
2275
2276 if (Ops.size() == 1) return Ops[0];
2277 }
2278
2279 // Limit recursion calls depth.
2280 if (Depth > MaxArithDepth)
2281 return getOrCreateAddExpr(Ops, Flags);
2282
2283 // Okay, check to see if the same value occurs in the operand list more than
2284 // once. If so, merge them together into an multiply expression. Since we
2285 // sorted the list, these values are required to be adjacent.
2286 Type *Ty = Ops[0]->getType();
2287 bool FoundMatch = false;
2288 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2289 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2290 // Scan ahead to count how many equal operands there are.
2291 unsigned Count = 2;
2292 while (i+Count != e && Ops[i+Count] == Ops[i])
2293 ++Count;
2294 // Merge the values into a multiply.
2295 const SCEV *Scale = getConstant(Ty, Count);
2296 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2297 if (Ops.size() == Count)
2298 return Mul;
2299 Ops[i] = Mul;
2300 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2301 --i; e -= Count - 1;
2302 FoundMatch = true;
2303 }
2304 if (FoundMatch)
2305 return getAddExpr(Ops, Flags);
2306
2307 // Check for truncates. If all the operands are truncated from the same
2308 // type, see if factoring out the truncate would permit the result to be
2309 // folded. eg., trunc(x) + m*trunc(n) --> trunc(x + trunc(m)*n)
2310 // if the contents of the resulting outer trunc fold to something simple.
2311 for (; Idx < Ops.size() && isa<SCEVTruncateExpr>(Ops[Idx]); ++Idx) {
2312 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(Ops[Idx]);
2313 Type *DstType = Trunc->getType();
2314 Type *SrcType = Trunc->getOperand()->getType();
2315 SmallVector<const SCEV *, 8> LargeOps;
2316 bool Ok = true;
2317 // Check all the operands to see if they can be represented in the
2318 // source type of the truncate.
2319 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2320 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2321 if (T->getOperand()->getType() != SrcType) {
2322 Ok = false;
2323 break;
2324 }
2325 LargeOps.push_back(T->getOperand());
2326 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2327 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2328 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2329 SmallVector<const SCEV *, 8> LargeMulOps;
2330 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2331 if (const SCEVTruncateExpr *T =
2332 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2333 if (T->getOperand()->getType() != SrcType) {
2334 Ok = false;
2335 break;
2336 }
2337 LargeMulOps.push_back(T->getOperand());
2338 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2339 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2340 } else {
2341 Ok = false;
2342 break;
2343 }
2344 }
2345 if (Ok)
2346 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2347 } else {
2348 Ok = false;
2349 break;
2350 }
2351 }
2352 if (Ok) {
2353 // Evaluate the expression in the larger type.
2354 const SCEV *Fold = getAddExpr(LargeOps, Flags, Depth + 1);
2355 // If it folds to something simple, use it. Otherwise, don't.
2356 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2357 return getTruncateExpr(Fold, DstType);
2358 }
2359 }
2360
2361 // Skip past any other cast SCEVs.
2362 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2363 ++Idx;
2364
2365 // If there are add operands they would be next.
2366 if (Idx < Ops.size()) {
2367 bool DeletedAdd = false;
2368 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2369 if (Ops.size() > AddOpsInlineThreshold ||
2370 Add->getNumOperands() > AddOpsInlineThreshold)
2371 break;
2372 // If we have an add, expand the add operands onto the end of the operands
2373 // list.
2374 Ops.erase(Ops.begin()+Idx);
2375 Ops.append(Add->op_begin(), Add->op_end());
2376 DeletedAdd = true;
2377 }
2378
2379 // If we deleted at least one add, we added operands to the end of the list,
2380 // and they are not necessarily sorted. Recurse to resort and resimplify
2381 // any operands we just acquired.
2382 if (DeletedAdd)
2383 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2384 }
2385
2386 // Skip over the add expression until we get to a multiply.
2387 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2388 ++Idx;
2389
2390 // Check to see if there are any folding opportunities present with
2391 // operands multiplied by constant values.
2392 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2393 uint64_t BitWidth = getTypeSizeInBits(Ty);
2394 DenseMap<const SCEV *, APInt> M;
2395 SmallVector<const SCEV *, 8> NewOps;
2396 APInt AccumulatedConstant(BitWidth, 0);
2397 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2398 Ops.data(), Ops.size(),
2399 APInt(BitWidth, 1), *this)) {
2400 struct APIntCompare {
2401 bool operator()(const APInt &LHS, const APInt &RHS) const {
2402 return LHS.ult(RHS);
2403 }
2404 };
2405
2406 // Some interesting folding opportunity is present, so its worthwhile to
2407 // re-generate the operands list. Group the operands by constant scale,
2408 // to avoid multiplying by the same constant scale multiple times.
2409 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2410 for (const SCEV *NewOp : NewOps)
2411 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2412 // Re-generate the operands list.
2413 Ops.clear();
2414 if (AccumulatedConstant != 0)
2415 Ops.push_back(getConstant(AccumulatedConstant));
2416 for (auto &MulOp : MulOpLists)
2417 if (MulOp.first != 0)
2418 Ops.push_back(getMulExpr(
2419 getConstant(MulOp.first),
2420 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2421 SCEV::FlagAnyWrap, Depth + 1));
2422 if (Ops.empty())
2423 return getZero(Ty);
2424 if (Ops.size() == 1)
2425 return Ops[0];
2426 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2427 }
2428 }
2429
2430 // If we are adding something to a multiply expression, make sure the
2431 // something is not already an operand of the multiply. If so, merge it into
2432 // the multiply.
2433 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2434 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2435 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2436 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2437 if (isa<SCEVConstant>(MulOpSCEV))
2438 continue;
2439 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2440 if (MulOpSCEV == Ops[AddOp]) {
2441 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2442 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2443 if (Mul->getNumOperands() != 2) {
2444 // If the multiply has more than two operands, we must get the
2445 // Y*Z term.
2446 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2447 Mul->op_begin()+MulOp);
2448 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2449 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2450 }
2451 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2452 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2453 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2454 SCEV::FlagAnyWrap, Depth + 1);
2455 if (Ops.size() == 2) return OuterMul;
2456 if (AddOp < Idx) {
2457 Ops.erase(Ops.begin()+AddOp);
2458 Ops.erase(Ops.begin()+Idx-1);
2459 } else {
2460 Ops.erase(Ops.begin()+Idx);
2461 Ops.erase(Ops.begin()+AddOp-1);
2462 }
2463 Ops.push_back(OuterMul);
2464 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2465 }
2466
2467 // Check this multiply against other multiplies being added together.
2468 for (unsigned OtherMulIdx = Idx+1;
2469 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2470 ++OtherMulIdx) {
2471 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2472 // If MulOp occurs in OtherMul, we can fold the two multiplies
2473 // together.
2474 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2475 OMulOp != e; ++OMulOp)
2476 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2477 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2478 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2479 if (Mul->getNumOperands() != 2) {
2480 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2481 Mul->op_begin()+MulOp);
2482 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2483 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2484 }
2485 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2486 if (OtherMul->getNumOperands() != 2) {
2487 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2488 OtherMul->op_begin()+OMulOp);
2489 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2490 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2491 }
2492 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2493 const SCEV *InnerMulSum =
2494 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2495 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2496 SCEV::FlagAnyWrap, Depth + 1);
2497 if (Ops.size() == 2) return OuterMul;
2498 Ops.erase(Ops.begin()+Idx);
2499 Ops.erase(Ops.begin()+OtherMulIdx-1);
2500 Ops.push_back(OuterMul);
2501 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2502 }
2503 }
2504 }
2505 }
2506
2507 // If there are any add recurrences in the operands list, see if any other
2508 // added values are loop invariant. If so, we can fold them into the
2509 // recurrence.
2510 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2511 ++Idx;
2512
2513 // Scan over all recurrences, trying to fold loop invariants into them.
2514 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2515 // Scan all of the other operands to this add and add them to the vector if
2516 // they are loop invariant w.r.t. the recurrence.
2517 SmallVector<const SCEV *, 8> LIOps;
2518 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2519 const Loop *AddRecLoop = AddRec->getLoop();
2520 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2521 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2522 LIOps.push_back(Ops[i]);
2523 Ops.erase(Ops.begin()+i);
2524 --i; --e;
2525 }
2526
2527 // If we found some loop invariants, fold them into the recurrence.
2528 if (!LIOps.empty()) {
2529 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2530 LIOps.push_back(AddRec->getStart());
2531
2532 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2533 AddRec->op_end());
2534 // This follows from the fact that the no-wrap flags on the outer add
2535 // expression are applicable on the 0th iteration, when the add recurrence
2536 // will be equal to its start value.
2537 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2538
2539 // Build the new addrec. Propagate the NUW and NSW flags if both the
2540 // outer add and the inner addrec are guaranteed to have no overflow.
2541 // Always propagate NW.
2542 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2543 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2544
2545 // If all of the other operands were loop invariant, we are done.
2546 if (Ops.size() == 1) return NewRec;
2547
2548 // Otherwise, add the folded AddRec by the non-invariant parts.
2549 for (unsigned i = 0;; ++i)
2550 if (Ops[i] == AddRec) {
2551 Ops[i] = NewRec;
2552 break;
2553 }
2554 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2555 }
2556
2557 // Okay, if there weren't any loop invariants to be folded, check to see if
2558 // there are multiple AddRec's with the same loop induction variable being
2559 // added together. If so, we can fold them.
2560 for (unsigned OtherIdx = Idx+1;
2561 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2562 ++OtherIdx) {
2563 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2564 // so that the 1st found AddRecExpr is dominated by all others.
2565 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2568, __PRETTY_FUNCTION__))
2566 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2568, __PRETTY_FUNCTION__))
2567 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2568, __PRETTY_FUNCTION__))
2568 "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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2568, __PRETTY_FUNCTION__))
;
2569 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2570 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2571 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2572 AddRec->op_end());
2573 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2574 ++OtherIdx) {
2575 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2576 if (OtherAddRec->getLoop() == AddRecLoop) {
2577 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2578 i != e; ++i) {
2579 if (i >= AddRecOps.size()) {
2580 AddRecOps.append(OtherAddRec->op_begin()+i,
2581 OtherAddRec->op_end());
2582 break;
2583 }
2584 SmallVector<const SCEV *, 2> TwoOps = {
2585 AddRecOps[i], OtherAddRec->getOperand(i)};
2586 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2587 }
2588 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2589 }
2590 }
2591 // Step size has changed, so we cannot guarantee no self-wraparound.
2592 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2593 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2594 }
2595 }
2596
2597 // Otherwise couldn't fold anything into this recurrence. Move onto the
2598 // next one.
2599 }
2600
2601 // Okay, it looks like we really DO need an add expr. Check to see if we
2602 // already have one, otherwise create a new one.
2603 return getOrCreateAddExpr(Ops, Flags);
2604}
2605
2606const SCEV *
2607ScalarEvolution::getOrCreateAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2608 SCEV::NoWrapFlags Flags) {
2609 FoldingSetNodeID ID;
2610 ID.AddInteger(scAddExpr);
2611 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2612 ID.AddPointer(Ops[i]);
2613 void *IP = nullptr;
2614 SCEVAddExpr *S =
2615 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2616 if (!S) {
2617 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2618 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2619 S = new (SCEVAllocator)
2620 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2621 UniqueSCEVs.InsertNode(S, IP);
2622 }
2623 S->setNoWrapFlags(Flags);
2624 return S;
2625}
2626
2627const SCEV *
2628ScalarEvolution::getOrCreateMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2629 SCEV::NoWrapFlags Flags) {
2630 FoldingSetNodeID ID;
2631 ID.AddInteger(scMulExpr);
2632 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2633 ID.AddPointer(Ops[i]);
2634 void *IP = nullptr;
2635 SCEVMulExpr *S =
2636 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2637 if (!S) {
2638 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2639 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2640 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2641 O, Ops.size());
2642 UniqueSCEVs.InsertNode(S, IP);
2643 }
2644 S->setNoWrapFlags(Flags);
2645 return S;
2646}
2647
2648static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2649 uint64_t k = i*j;
2650 if (j > 1 && k / j != i) Overflow = true;
2651 return k;
2652}
2653
2654/// Compute the result of "n choose k", the binomial coefficient. If an
2655/// intermediate computation overflows, Overflow will be set and the return will
2656/// be garbage. Overflow is not cleared on absence of overflow.
2657static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2658 // We use the multiplicative formula:
2659 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2660 // At each iteration, we take the n-th term of the numeral and divide by the
2661 // (k-n)th term of the denominator. This division will always produce an
2662 // integral result, and helps reduce the chance of overflow in the
2663 // intermediate computations. However, we can still overflow even when the
2664 // final result would fit.
2665
2666 if (n == 0 || n == k) return 1;
2667 if (k > n) return 0;
2668
2669 if (k > n/2)
2670 k = n-k;
2671
2672 uint64_t r = 1;
2673 for (uint64_t i = 1; i <= k; ++i) {
2674 r = umul_ov(r, n-(i-1), Overflow);
2675 r /= i;
2676 }
2677 return r;
2678}
2679
2680/// Determine if any of the operands in this SCEV are a constant or if
2681/// any of the add or multiply expressions in this SCEV contain a constant.
2682static bool containsConstantSomewhere(const SCEV *StartExpr) {
2683 SmallVector<const SCEV *, 4> Ops;
2684 Ops.push_back(StartExpr);
2685 while (!Ops.empty()) {
2686 const SCEV *CurrentExpr = Ops.pop_back_val();
2687 if (isa<SCEVConstant>(*CurrentExpr))
2688 return true;
2689
2690 if (isa<SCEVAddExpr>(*CurrentExpr) || isa<SCEVMulExpr>(*CurrentExpr)) {
2691 const auto *CurrentNAry = cast<SCEVNAryExpr>(CurrentExpr);
2692 Ops.append(CurrentNAry->op_begin(), CurrentNAry->op_end());
2693 }
2694 }
2695 return false;
2696}
2697
2698/// Get a canonical multiply expression, or something simpler if possible.
2699const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2700 SCEV::NoWrapFlags Flags,
2701 unsigned Depth) {
2702 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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2703, __PRETTY_FUNCTION__))
2703 "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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2703, __PRETTY_FUNCTION__))
;
2704 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2704, __PRETTY_FUNCTION__))
;
2705 if (Ops.size() == 1) return Ops[0];
2706#ifndef NDEBUG
2707 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2708 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2709 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2710, __PRETTY_FUNCTION__))
2710 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2710, __PRETTY_FUNCTION__))
;
2711#endif
2712
2713 // Sort by complexity, this groups all similar expression types together.
2714 GroupByComplexity(Ops, &LI, DT);
2715
2716 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2717
2718 // Limit recursion calls depth.
2719 if (Depth > MaxArithDepth)
2720 return getOrCreateMulExpr(Ops, Flags);
2721
2722 // If there are any constants, fold them together.
2723 unsigned Idx = 0;
2724 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2725
2726 // C1*(C2+V) -> C1*C2 + C1*V
2727 if (Ops.size() == 2)
2728 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2729 // If any of Add's ops are Adds or Muls with a constant,
2730 // apply this transformation as well.
2731 if (Add->getNumOperands() == 2)
2732 if (containsConstantSomewhere(Add))
2733 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2734 SCEV::FlagAnyWrap, Depth + 1),
2735 getMulExpr(LHSC, Add->getOperand(1),
2736 SCEV::FlagAnyWrap, Depth + 1),
2737 SCEV::FlagAnyWrap, Depth + 1);
2738
2739 ++Idx;
2740 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2741 // We found two constants, fold them together!
2742 ConstantInt *Fold =
2743 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2744 Ops[0] = getConstant(Fold);
2745 Ops.erase(Ops.begin()+1); // Erase the folded element
2746 if (Ops.size() == 1) return Ops[0];
2747 LHSC = cast<SCEVConstant>(Ops[0]);
2748 }
2749
2750 // If we are left with a constant one being multiplied, strip it off.
2751 if (cast<SCEVConstant>(Ops[0])->getValue()->equalsInt(1)) {
2752 Ops.erase(Ops.begin());
2753 --Idx;
2754 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2755 // If we have a multiply of zero, it will always be zero.
2756 return Ops[0];
2757 } else if (Ops[0]->isAllOnesValue()) {
2758 // If we have a mul by -1 of an add, try distributing the -1 among the
2759 // add operands.
2760 if (Ops.size() == 2) {
2761 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2762 SmallVector<const SCEV *, 4> NewOps;
2763 bool AnyFolded = false;
2764 for (const SCEV *AddOp : Add->operands()) {
2765 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2766 Depth + 1);
2767 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2768 NewOps.push_back(Mul);
2769 }
2770 if (AnyFolded)
2771 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2772 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2773 // Negation preserves a recurrence's no self-wrap property.
2774 SmallVector<const SCEV *, 4> Operands;
2775 for (const SCEV *AddRecOp : AddRec->operands())
2776 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2777 Depth + 1));
2778
2779 return getAddRecExpr(Operands, AddRec->getLoop(),
2780 AddRec->getNoWrapFlags(SCEV::FlagNW));
2781 }
2782 }
2783 }
2784
2785 if (Ops.size() == 1)
2786 return Ops[0];
2787 }
2788
2789 // Skip over the add expression until we get to a multiply.
2790 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2791 ++Idx;
2792
2793 // If there are mul operands inline them all into this expression.
2794 if (Idx < Ops.size()) {
2795 bool DeletedMul = false;
2796 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2797 if (Ops.size() > MulOpsInlineThreshold)
2798 break;
2799 // If we have an mul, expand the mul operands onto the end of the
2800 // operands list.
2801 Ops.erase(Ops.begin()+Idx);
2802 Ops.append(Mul->op_begin(), Mul->op_end());
2803 DeletedMul = true;
2804 }
2805
2806 // If we deleted at least one mul, we added operands to the end of the
2807 // list, and they are not necessarily sorted. Recurse to resort and
2808 // resimplify any operands we just acquired.
2809 if (DeletedMul)
2810 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2811 }
2812
2813 // If there are any add recurrences in the operands list, see if any other
2814 // added values are loop invariant. If so, we can fold them into the
2815 // recurrence.
2816 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2817 ++Idx;
2818
2819 // Scan over all recurrences, trying to fold loop invariants into them.
2820 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2821 // Scan all of the other operands to this mul and add them to the vector
2822 // if they are loop invariant w.r.t. the recurrence.
2823 SmallVector<const SCEV *, 8> LIOps;
2824 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2825 const Loop *AddRecLoop = AddRec->getLoop();
2826 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2827 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2828 LIOps.push_back(Ops[i]);
2829 Ops.erase(Ops.begin()+i);
2830 --i; --e;
2831 }
2832
2833 // If we found some loop invariants, fold them into the recurrence.
2834 if (!LIOps.empty()) {
2835 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2836 SmallVector<const SCEV *, 4> NewOps;
2837 NewOps.reserve(AddRec->getNumOperands());
2838 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
2839 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2840 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
2841 SCEV::FlagAnyWrap, Depth + 1));
2842
2843 // Build the new addrec. Propagate the NUW and NSW flags if both the
2844 // outer mul and the inner addrec are guaranteed to have no overflow.
2845 //
2846 // No self-wrap cannot be guaranteed after changing the step size, but
2847 // will be inferred if either NUW or NSW is true.
2848 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
2849 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
2850
2851 // If all of the other operands were loop invariant, we are done.
2852 if (Ops.size() == 1) return NewRec;
2853
2854 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2855 for (unsigned i = 0;; ++i)
2856 if (Ops[i] == AddRec) {
2857 Ops[i] = NewRec;
2858 break;
2859 }
2860 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2861 }
2862
2863 // Okay, if there weren't any loop invariants to be folded, check to see
2864 // if there are multiple AddRec's with the same loop induction variable
2865 // being multiplied together. If so, we can fold them.
2866
2867 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2868 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2869 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2870 // ]]],+,...up to x=2n}.
2871 // Note that the arguments to choose() are always integers with values
2872 // known at compile time, never SCEV objects.
2873 //
2874 // The implementation avoids pointless extra computations when the two
2875 // addrec's are of different length (mathematically, it's equivalent to
2876 // an infinite stream of zeros on the right).
2877 bool OpsModified = false;
2878 for (unsigned OtherIdx = Idx+1;
2879 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2880 ++OtherIdx) {
2881 const SCEVAddRecExpr *OtherAddRec =
2882 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2883 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
2884 continue;
2885
2886 bool Overflow = false;
2887 Type *Ty = AddRec->getType();
2888 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
2889 SmallVector<const SCEV*, 7> AddRecOps;
2890 for (int x = 0, xe = AddRec->getNumOperands() +
2891 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
2892 const SCEV *Term = getZero(Ty);
2893 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
2894 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
2895 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
2896 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
2897 z < ze && !Overflow; ++z) {
2898 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
2899 uint64_t Coeff;
2900 if (LargerThan64Bits)
2901 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
2902 else
2903 Coeff = Coeff1*Coeff2;
2904 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
2905 const SCEV *Term1 = AddRec->getOperand(y-z);
2906 const SCEV *Term2 = OtherAddRec->getOperand(z);
2907 Term = getAddExpr(Term, getMulExpr(CoeffTerm, Term1, Term2,
2908 SCEV::FlagAnyWrap, Depth + 1),
2909 SCEV::FlagAnyWrap, Depth + 1);
2910 }
2911 }
2912 AddRecOps.push_back(Term);
2913 }
2914 if (!Overflow) {
2915 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(),
2916 SCEV::FlagAnyWrap);
2917 if (Ops.size() == 2) return NewAddRec;
2918 Ops[Idx] = NewAddRec;
2919 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2920 OpsModified = true;
2921 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
2922 if (!AddRec)
2923 break;
2924 }
2925 }
2926 if (OpsModified)
2927 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2928
2929 // Otherwise couldn't fold anything into this recurrence. Move onto the
2930 // next one.
2931 }
2932
2933 // Okay, it looks like we really DO need an mul expr. Check to see if we
2934 // already have one, otherwise create a new one.
2935 return getOrCreateMulExpr(Ops, Flags);
2936}
2937
2938/// Get a canonical unsigned division expression, or something simpler if
2939/// possible.
2940const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
2941 const SCEV *RHS) {
2942 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2944, __PRETTY_FUNCTION__))
2943 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2944, __PRETTY_FUNCTION__))
2944 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 2944, __PRETTY_FUNCTION__))
;
2945
2946 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
2947 if (RHSC->getValue()->equalsInt(1))
2948 return LHS; // X udiv 1 --> x
2949 // If the denominator is zero, the result of the udiv is undefined. Don't
2950 // try to analyze it, because the resolution chosen here may differ from
2951 // the resolution chosen in other parts of the compiler.
2952 if (!RHSC->getValue()->isZero()) {
2953 // Determine if the division can be folded into the operands of
2954 // its operands.
2955 // TODO: Generalize this to non-constants by using known-bits information.
2956 Type *Ty = LHS->getType();
2957 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
2958 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
2959 // For non-power-of-two values, effectively round the value up to the
2960 // nearest power of two.
2961 if (!RHSC->getAPInt().isPowerOf2())
2962 ++MaxShiftAmt;
2963 IntegerType *ExtTy =
2964 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
2965 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
2966 if (const SCEVConstant *Step =
2967 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
2968 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
2969 const APInt &StepInt = Step->getAPInt();
2970 const APInt &DivInt = RHSC->getAPInt();
2971 if (!StepInt.urem(DivInt) &&
2972 getZeroExtendExpr(AR, ExtTy) ==
2973 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2974 getZeroExtendExpr(Step, ExtTy),
2975 AR->getLoop(), SCEV::FlagAnyWrap)) {
2976 SmallVector<const SCEV *, 4> Operands;
2977 for (const SCEV *Op : AR->operands())
2978 Operands.push_back(getUDivExpr(Op, RHS));
2979 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
2980 }
2981 /// Get a canonical UDivExpr for a recurrence.
2982 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
2983 // We can currently only fold X%N if X is constant.
2984 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
2985 if (StartC && !DivInt.urem(StepInt) &&
2986 getZeroExtendExpr(AR, ExtTy) ==
2987 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2988 getZeroExtendExpr(Step, ExtTy),
2989 AR->getLoop(), SCEV::FlagAnyWrap)) {
2990 const APInt &StartInt = StartC->getAPInt();
2991 const APInt &StartRem = StartInt.urem(StepInt);
2992 if (StartRem != 0)
2993 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
2994 AR->getLoop(), SCEV::FlagNW);
2995 }
2996 }
2997 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
2998 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
2999 SmallVector<const SCEV *, 4> Operands;
3000 for (const SCEV *Op : M->operands())
3001 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3002 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3003 // Find an operand that's safely divisible.
3004 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3005 const SCEV *Op = M->getOperand(i);
3006 const SCEV *Div = getUDivExpr(Op, RHSC);
3007 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3008 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
3009 M->op_end());
3010 Operands[i] = Div;
3011 return getMulExpr(Operands);
3012 }
3013 }
3014 }
3015 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3016 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3017 SmallVector<const SCEV *, 4> Operands;
3018 for (const SCEV *Op : A->operands())
3019 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3020 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3021 Operands.clear();
3022 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3023 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3024 if (isa<SCEVUDivExpr>(Op) ||
3025 getMulExpr(Op, RHS) != A->getOperand(i))
3026 break;
3027 Operands.push_back(Op);
3028 }
3029 if (Operands.size() == A->getNumOperands())
3030 return getAddExpr(Operands);
3031 }
3032 }
3033
3034 // Fold if both operands are constant.
3035 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3036 Constant *LHSCV = LHSC->getValue();
3037 Constant *RHSCV = RHSC->getValue();
3038 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3039 RHSCV)));
3040 }
3041 }
3042 }
3043
3044 FoldingSetNodeID ID;
3045 ID.AddInteger(scUDivExpr);
3046 ID.AddPointer(LHS);
3047 ID.AddPointer(RHS);
3048 void *IP = nullptr;
3049 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3050 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3051 LHS, RHS);
3052 UniqueSCEVs.InsertNode(S, IP);
3053 return S;
3054}
3055
3056static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3057 APInt A = C1->getAPInt().abs();
3058 APInt B = C2->getAPInt().abs();
3059 uint32_t ABW = A.getBitWidth();
3060 uint32_t BBW = B.getBitWidth();
3061
3062 if (ABW > BBW)
3063 B = B.zext(ABW);
3064 else if (ABW < BBW)
3065 A = A.zext(BBW);
3066
3067 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3068}
3069
3070/// Get a canonical unsigned division expression, or something simpler if
3071/// possible. There is no representation for an exact udiv in SCEV IR, but we
3072/// can attempt to remove factors from the LHS and RHS. We can't do this when
3073/// it's not exact because the udiv may be clearing bits.
3074const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3075 const SCEV *RHS) {
3076 // TODO: we could try to find factors in all sorts of things, but for now we
3077 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3078 // end of this file for inspiration.
3079
3080 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3081 if (!Mul || !Mul->hasNoUnsignedWrap())
3082 return getUDivExpr(LHS, RHS);
3083
3084 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3085 // If the mulexpr multiplies by a constant, then that constant must be the
3086 // first element of the mulexpr.
3087 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3088 if (LHSCst == RHSCst) {
3089 SmallVector<const SCEV *, 2> Operands;
3090 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3091 return getMulExpr(Operands);
3092 }
3093
3094 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3095 // that there's a factor provided by one of the other terms. We need to
3096 // check.
3097 APInt Factor = gcd(LHSCst, RHSCst);
3098 if (!Factor.isIntN(1)) {
3099 LHSCst =
3100 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3101 RHSCst =
3102 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3103 SmallVector<const SCEV *, 2> Operands;
3104 Operands.push_back(LHSCst);
3105 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3106 LHS = getMulExpr(Operands);
3107 RHS = RHSCst;
3108 Mul = dyn_cast<SCEVMulExpr>(LHS);
3109 if (!Mul)
3110 return getUDivExactExpr(LHS, RHS);
3111 }
3112 }
3113 }
3114
3115 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3116 if (Mul->getOperand(i) == RHS) {
3117 SmallVector<const SCEV *, 2> Operands;
3118 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3119 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3120 return getMulExpr(Operands);
3121 }
3122 }
3123
3124 return getUDivExpr(LHS, RHS);
3125}
3126
3127/// Get an add recurrence expression for the specified loop. Simplify the
3128/// expression as much as possible.
3129const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3130 const Loop *L,
3131 SCEV::NoWrapFlags Flags) {
3132 SmallVector<const SCEV *, 4> Operands;
3133 Operands.push_back(Start);
3134 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3135 if (StepChrec->getLoop() == L) {
3136 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3137 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3138 }
3139
3140 Operands.push_back(Step);
3141 return getAddRecExpr(Operands, L, Flags);
3142}
3143
3144/// Get an add recurrence expression for the specified loop. Simplify the
3145/// expression as much as possible.
3146const SCEV *
3147ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3148 const Loop *L, SCEV::NoWrapFlags Flags) {
3149 if (Operands.size() == 1) return Operands[0];
3150#ifndef NDEBUG
3151 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3152 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3153 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3154, __PRETTY_FUNCTION__))
3154 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3154, __PRETTY_FUNCTION__))
;
3155 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3156 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3157, __PRETTY_FUNCTION__))
3157 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3157, __PRETTY_FUNCTION__))
;
3158#endif
3159
3160 if (Operands.back()->isZero()) {
3161 Operands.pop_back();
3162 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3163 }
3164
3165 // It's tempting to want to call getMaxBackedgeTakenCount count here and
3166 // use that information to infer NUW and NSW flags. However, computing a
3167 // BE count requires calling getAddRecExpr, so we may not yet have a
3168 // meaningful BE count at this point (and if we don't, we'd be stuck
3169 // with a SCEVCouldNotCompute as the cached BE count).
3170
3171 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3172
3173 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3174 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3175 const Loop *NestedLoop = NestedAR->getLoop();
3176 if (L->contains(NestedLoop)
3177 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3178 : (!NestedLoop->contains(L) &&
3179 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3180 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
3181 NestedAR->op_end());
3182 Operands[0] = NestedAR->getStart();
3183 // AddRecs require their operands be loop-invariant with respect to their
3184 // loops. Don't perform this transformation if it would break this
3185 // requirement.
3186 bool AllInvariant = all_of(
3187 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3188
3189 if (AllInvariant) {
3190 // Create a recurrence for the outer loop with the same step size.
3191 //
3192 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3193 // inner recurrence has the same property.
3194 SCEV::NoWrapFlags OuterFlags =
3195 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3196
3197 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3198 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3199 return isLoopInvariant(Op, NestedLoop);
3200 });
3201
3202 if (AllInvariant) {
3203 // Ok, both add recurrences are valid after the transformation.
3204 //
3205 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3206 // the outer recurrence has the same property.
3207 SCEV::NoWrapFlags InnerFlags =
3208 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3209 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3210 }
3211 }
3212 // Reset Operands to its original state.
3213 Operands[0] = NestedAR;
3214 }
3215 }
3216
3217 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3218 // already have one, otherwise create a new one.
3219 FoldingSetNodeID ID;
3220 ID.AddInteger(scAddRecExpr);
3221 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3222 ID.AddPointer(Operands[i]);
3223 ID.AddPointer(L);
3224 void *IP = nullptr;
3225 SCEVAddRecExpr *S =
3226 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
3227 if (!S) {
3228 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
3229 std::uninitialized_copy(Operands.begin(), Operands.end(), O);
3230 S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator),
3231 O, Operands.size(), L);
3232 UniqueSCEVs.InsertNode(S, IP);
3233 }
3234 S->setNoWrapFlags(Flags);
3235 return S;
3236}
3237
3238const SCEV *
3239ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3240 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3241 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3242 // getSCEV(Base)->getType() has the same address space as Base->getType()
3243 // because SCEV::getType() preserves the address space.
3244 Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType());
3245 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3246 // instruction to its SCEV, because the Instruction may be guarded by control
3247 // flow and the no-overflow bits may not be valid for the expression in any
3248 // context. This can be fixed similarly to how these flags are handled for
3249 // adds.
3250 SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW
3251 : SCEV::FlagAnyWrap;
3252
3253 const SCEV *TotalOffset = getZero(IntPtrTy);
3254 // The array size is unimportant. The first thing we do on CurTy is getting
3255 // its element type.
3256 Type *CurTy = ArrayType::get(GEP->getSourceElementType(), 0);
3257 for (const SCEV *IndexExpr : IndexExprs) {
3258 // Compute the (potentially symbolic) offset in bytes for this index.
3259 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3260 // For a struct, add the member offset.
3261 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3262 unsigned FieldNo = Index->getZExtValue();
3263 const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo);
3264
3265 // Add the field offset to the running total offset.
3266 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3267
3268 // Update CurTy to the type of the field at Index.
3269 CurTy = STy->getTypeAtIndex(Index);
3270 } else {
3271 // Update CurTy to its element type.
3272 CurTy = cast<SequentialType>(CurTy)->getElementType();
3273 // For an array, add the element offset, explicitly scaled.
3274 const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy);
3275 // Getelementptr indices are signed.
3276 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy);
3277
3278 // Multiply the index by the element size to compute the element offset.
3279 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3280
3281 // Add the element offset to the running total offset.
3282 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3283 }
3284 }
3285
3286 // Add the total offset from all the GEP indices to the base.
3287 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3288}
3289
3290const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS,
3291 const SCEV *RHS) {
3292 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3293 return getSMaxExpr(Ops);
3294}
3295
3296const SCEV *
3297ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3298 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3298, __PRETTY_FUNCTION__))
;
3299 if (Ops.size() == 1) return Ops[0];
3300#ifndef NDEBUG
3301 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3302 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3303 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3304, __PRETTY_FUNCTION__))
3304 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3304, __PRETTY_FUNCTION__))
;
3305#endif
3306
3307 // Sort by complexity, this groups all similar expression types together.
3308 GroupByComplexity(Ops, &LI, DT);
3309
3310 // If there are any constants, fold them together.
3311 unsigned Idx = 0;
3312 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3313 ++Idx;
3314 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3314, __PRETTY_FUNCTION__))
;
3315 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3316 // We found two constants, fold them together!
3317 ConstantInt *Fold = ConstantInt::get(
3318 getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt()));
3319 Ops[0] = getConstant(Fold);
3320 Ops.erase(Ops.begin()+1); // Erase the folded element
3321 if (Ops.size() == 1) return Ops[0];
3322 LHSC = cast<SCEVConstant>(Ops[0]);
3323 }
3324
3325 // If we are left with a constant minimum-int, strip it off.
3326 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
3327 Ops.erase(Ops.begin());
3328 --Idx;
3329 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
3330 // If we have an smax with a constant maximum-int, it will always be
3331 // maximum-int.
3332 return Ops[0];
3333 }
3334
3335 if (Ops.size() == 1) return Ops[0];
3336 }
3337
3338 // Find the first SMax
3339 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
3340 ++Idx;
3341
3342 // Check to see if one of the operands is an SMax. If so, expand its operands
3343 // onto our operand list, and recurse to simplify.
3344 if (Idx < Ops.size()) {
3345 bool DeletedSMax = false;
3346 while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
3347 Ops.erase(Ops.begin()+Idx);
3348 Ops.append(SMax->op_begin(), SMax->op_end());
3349 DeletedSMax = true;
3350 }
3351
3352 if (DeletedSMax)
3353 return getSMaxExpr(Ops);
3354 }
3355
3356 // Okay, check to see if the same value occurs in the operand list twice. If
3357 // so, delete one. Since we sorted the list, these values are required to
3358 // be adjacent.
3359 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3360 // X smax Y smax Y --> X smax Y
3361 // X smax Y --> X, if X is always greater than Y
3362 if (Ops[i] == Ops[i+1] ||
3363 isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
3364 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3365 --i; --e;
3366 } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
3367 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3368 --i; --e;
3369 }
3370
3371 if (Ops.size() == 1) return Ops[0];
3372
3373 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3373, __PRETTY_FUNCTION__))
;
3374
3375 // Okay, it looks like we really DO need an smax expr. Check to see if we
3376 // already have one, otherwise create a new one.
3377 FoldingSetNodeID ID;
3378 ID.AddInteger(scSMaxExpr);
3379 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3380 ID.AddPointer(Ops[i]);
3381 void *IP = nullptr;
3382 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3383 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3384 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3385 SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
3386 O, Ops.size());
3387 UniqueSCEVs.InsertNode(S, IP);
3388 return S;
3389}
3390
3391const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS,
3392 const SCEV *RHS) {
3393 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3394 return getUMaxExpr(Ops);
3395}
3396
3397const SCEV *
3398ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3399 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3399, __PRETTY_FUNCTION__))
;
3400 if (Ops.size() == 1) return Ops[0];
3401#ifndef NDEBUG
3402 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3403 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3404 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3405, __PRETTY_FUNCTION__))
3405 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3405, __PRETTY_FUNCTION__))
;
3406#endif
3407
3408 // Sort by complexity, this groups all similar expression types together.
3409 GroupByComplexity(Ops, &LI, DT);
3410
3411 // If there are any constants, fold them together.
3412 unsigned Idx = 0;
3413 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3414 ++Idx;
3415 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3415, __PRETTY_FUNCTION__))
;
3416 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3417 // We found two constants, fold them together!
3418 ConstantInt *Fold = ConstantInt::get(
3419 getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt()));
3420 Ops[0] = getConstant(Fold);
3421 Ops.erase(Ops.begin()+1); // Erase the folded element
3422 if (Ops.size() == 1) return Ops[0];
3423 LHSC = cast<SCEVConstant>(Ops[0]);
3424 }
3425
3426 // If we are left with a constant minimum-int, strip it off.
3427 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
3428 Ops.erase(Ops.begin());
3429 --Idx;
3430 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
3431 // If we have an umax with a constant maximum-int, it will always be
3432 // maximum-int.
3433 return Ops[0];
3434 }
3435
3436 if (Ops.size() == 1) return Ops[0];
3437 }
3438
3439 // Find the first UMax
3440 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
3441 ++Idx;
3442
3443 // Check to see if one of the operands is a UMax. If so, expand its operands
3444 // onto our operand list, and recurse to simplify.
3445 if (Idx < Ops.size()) {
3446 bool DeletedUMax = false;
3447 while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
3448 Ops.erase(Ops.begin()+Idx);
3449 Ops.append(UMax->op_begin(), UMax->op_end());
3450 DeletedUMax = true;
3451 }
3452
3453 if (DeletedUMax)
3454 return getUMaxExpr(Ops);
3455 }
3456
3457 // Okay, check to see if the same value occurs in the operand list twice. If
3458 // so, delete one. Since we sorted the list, these values are required to
3459 // be adjacent.
3460 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3461 // X umax Y umax Y --> X umax Y
3462 // X umax Y --> X, if X is always greater than Y
3463 if (Ops[i] == Ops[i+1] ||
3464 isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
3465 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3466 --i; --e;
3467 } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
3468 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3469 --i; --e;
3470 }
3471
3472 if (Ops.size() == 1) return Ops[0];
3473
3474 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3474, __PRETTY_FUNCTION__))
;
3475
3476 // Okay, it looks like we really DO need a umax expr. Check to see if we
3477 // already have one, otherwise create a new one.
3478 FoldingSetNodeID ID;
3479 ID.AddInteger(scUMaxExpr);
3480 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3481 ID.AddPointer(Ops[i]);
3482 void *IP = nullptr;
3483 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3484 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3485 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3486 SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
3487 O, Ops.size());
3488 UniqueSCEVs.InsertNode(S, IP);
3489 return S;
3490}
3491
3492const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3493 const SCEV *RHS) {
3494 // ~smax(~x, ~y) == smin(x, y).
3495 return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3496}
3497
3498const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3499 const SCEV *RHS) {
3500 // ~umax(~x, ~y) == umin(x, y)
3501 return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3502}
3503
3504const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3505 // We can bypass creating a target-independent
3506 // constant expression and then folding it back into a ConstantInt.
3507 // This is just a compile-time optimization.
3508 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3509}
3510
3511const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3512 StructType *STy,
3513 unsigned FieldNo) {
3514 // We can bypass creating a target-independent
3515 // constant expression and then folding it back into a ConstantInt.
3516 // This is just a compile-time optimization.
3517 return getConstant(
3518 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3519}
3520
3521const SCEV *ScalarEvolution::getUnknown(Value *V) {
3522 // Don't attempt to do anything other than create a SCEVUnknown object
3523 // here. createSCEV only calls getUnknown after checking for all other
3524 // interesting possibilities, and any other code that calls getUnknown
3525 // is doing so in order to hide a value from SCEV canonicalization.
3526
3527 FoldingSetNodeID ID;
3528 ID.AddInteger(scUnknown);
3529 ID.AddPointer(V);
3530 void *IP = nullptr;
3531 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3532 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3533, __PRETTY_FUNCTION__))
3533 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3533, __PRETTY_FUNCTION__))
;
3534 return S;
3535 }
3536 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3537 FirstUnknown);
3538 FirstUnknown = cast<SCEVUnknown>(S);
3539 UniqueSCEVs.InsertNode(S, IP);
3540 return S;
3541}
3542
3543//===----------------------------------------------------------------------===//
3544// Basic SCEV Analysis and PHI Idiom Recognition Code
3545//
3546
3547/// Test if values of the given type are analyzable within the SCEV
3548/// framework. This primarily includes integer types, and it can optionally
3549/// include pointer types if the ScalarEvolution class has access to
3550/// target-specific information.
3551bool ScalarEvolution::isSCEVable(Type *Ty) const {
3552 // Integers and pointers are always SCEVable.
3553 return Ty->isIntegerTy() || Ty->isPointerTy();
3554}
3555
3556/// Return the size in bits of the specified type, for which isSCEVable must
3557/// return true.
3558uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3559 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3559, __PRETTY_FUNCTION__))
;
3560 return getDataLayout().getTypeSizeInBits(Ty);
3561}
3562
3563/// Return a type with the same bitwidth as the given type and which represents
3564/// how SCEV will treat the given type, for which isSCEVable must return
3565/// true. For pointer types, this is the pointer-sized integer type.
3566Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3567 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3567, __PRETTY_FUNCTION__))
;
3568
3569 if (Ty->isIntegerTy())
3570 return Ty;
3571
3572 // The only other support type is pointer.
3573 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3573, __PRETTY_FUNCTION__))
;
3574 return getDataLayout().getIntPtrType(Ty);
3575}
3576
3577Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3578 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3579}
3580
3581const SCEV *ScalarEvolution::getCouldNotCompute() {
3582 return CouldNotCompute.get();
3583}
3584
3585bool ScalarEvolution::checkValidity(const SCEV *S) const {
3586 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3587 auto *SU = dyn_cast<SCEVUnknown>(S);
3588 return SU && SU->getValue() == nullptr;
3589 });
3590
3591 return !ContainsNulls;
3592}
3593
3594bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3595 HasRecMapType::iterator I = HasRecMap.find(S);
3596 if (I != HasRecMap.end())
3597 return I->second;
3598
3599 bool FoundAddRec = SCEVExprContains(S, isa<SCEVAddRecExpr, const SCEV *>);
3600 HasRecMap.insert({S, FoundAddRec});
3601 return FoundAddRec;
3602}
3603
3604/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3605/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3606/// offset I, then return {S', I}, else return {\p S, nullptr}.
3607static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3608 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3609 if (!Add)
3610 return {S, nullptr};
3611
3612 if (Add->getNumOperands() != 2)
3613 return {S, nullptr};
3614
3615 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3616 if (!ConstOp)
3617 return {S, nullptr};
3618
3619 return {Add->getOperand(1), ConstOp->getValue()};
3620}
3621
3622/// Return the ValueOffsetPair set for \p S. \p S can be represented
3623/// by the value and offset from any ValueOffsetPair in the set.
3624SetVector<ScalarEvolution::ValueOffsetPair> *
3625ScalarEvolution::getSCEVValues(const SCEV *S) {
3626 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3627 if (SI == ExprValueMap.end())
3628 return nullptr;
3629#ifndef NDEBUG
3630 if (VerifySCEVMap) {
3631 // Check there is no dangling Value in the set returned.
3632 for (const auto &VE : SI->second)
3633 assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0)
: __assert_fail ("ValueExprMap.count(VE.first)", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3633, __PRETTY_FUNCTION__))
;
3634 }
3635#endif
3636 return &SI->second;
3637}
3638
3639/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3640/// cannot be used separately. eraseValueFromMap should be used to remove
3641/// V from ValueExprMap and ExprValueMap at the same time.
3642void ScalarEvolution::eraseValueFromMap(Value *V) {
3643 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3644 if (I != ValueExprMap.end()) {
3645 const SCEV *S = I->second;
3646 // Remove {V, 0} from the set of ExprValueMap[S]
3647 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3648 SV->remove({V, nullptr});
3649
3650 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3651 const SCEV *Stripped;
3652 ConstantInt *Offset;
3653 std::tie(Stripped, Offset) = splitAddExpr(S);
3654 if (Offset != nullptr) {
3655 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3656 SV->remove({V, Offset});
3657 }
3658 ValueExprMap.erase(V);
3659 }
3660}
3661
3662/// Return an existing SCEV if it exists, otherwise analyze the expression and
3663/// create a new one.
3664const SCEV *ScalarEvolution::getSCEV(Value *V) {
3665 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3665, __PRETTY_FUNCTION__))
;
3666
3667 const SCEV *S = getExistingSCEV(V);
3668 if (S == nullptr) {
3669 S = createSCEV(V);
3670 // During PHI resolution, it is possible to create two SCEVs for the same
3671 // V, so it is needed to double check whether V->S is inserted into
3672 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3673 std::pair<ValueExprMapType::iterator, bool> Pair =
3674 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3675 if (Pair.second) {
3676 ExprValueMap[S].insert({V, nullptr});
3677
3678 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3679 // ExprValueMap.
3680 const SCEV *Stripped = S;
3681 ConstantInt *Offset = nullptr;
3682 std::tie(Stripped, Offset) = splitAddExpr(S);
3683 // If stripped is SCEVUnknown, don't bother to save
3684 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3685 // increase the complexity of the expansion code.
3686 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3687 // because it may generate add/sub instead of GEP in SCEV expansion.
3688 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3689 !isa<GetElementPtrInst>(V))
3690 ExprValueMap[Stripped].insert({V, Offset});
3691 }
3692 }
3693 return S;
3694}
3695
3696const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3697 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3697, __PRETTY_FUNCTION__))
;
3698
3699 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3700 if (I != ValueExprMap.end()) {
3701 const SCEV *S = I->second;
3702 if (checkValidity(S))
3703 return S;
3704 eraseValueFromMap(V);
3705 forgetMemoizedResults(S);
3706 }
3707 return nullptr;
3708}
3709
3710/// Return a SCEV corresponding to -V = -1*V
3711///
3712const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3713 SCEV::NoWrapFlags Flags) {
3714 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3715 return getConstant(
3716 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3717
3718 Type *Ty = V->getType();
3719 Ty = getEffectiveSCEVType(Ty);
3720 return getMulExpr(
3721 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3722}
3723
3724/// Return a SCEV corresponding to ~V = -1-V
3725const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3726 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3727 return getConstant(
3728 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3729
3730 Type *Ty = V->getType();
3731 Ty = getEffectiveSCEVType(Ty);
3732 const SCEV *AllOnes =
3733 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3734 return getMinusSCEV(AllOnes, V);
3735}
3736
3737const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3738 SCEV::NoWrapFlags Flags,
3739 unsigned Depth) {
3740 // Fast path: X - X --> 0.
3741 if (LHS == RHS)
3742 return getZero(LHS->getType());
3743
3744 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3745 // makes it so that we cannot make much use of NUW.
3746 auto AddFlags = SCEV::FlagAnyWrap;
3747 const bool RHSIsNotMinSigned =
3748 !getSignedRangeMin(RHS).isMinSignedValue();
3749 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3750 // Let M be the minimum representable signed value. Then (-1)*RHS
3751 // signed-wraps if and only if RHS is M. That can happen even for
3752 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3753 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3754 // (-1)*RHS, we need to prove that RHS != M.
3755 //
3756 // If LHS is non-negative and we know that LHS - RHS does not
3757 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3758 // either by proving that RHS > M or that LHS >= 0.
3759 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
3760 AddFlags = SCEV::FlagNSW;
3761 }
3762 }
3763
3764 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
3765 // RHS is NSW and LHS >= 0.
3766 //
3767 // The difficulty here is that the NSW flag may have been proven
3768 // relative to a loop that is to be found in a recurrence in LHS and
3769 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
3770 // larger scope than intended.
3771 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3772
3773 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
3774}
3775
3776const SCEV *
3777ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) {
3778 Type *SrcTy = V->getType();
3779 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3781, __PRETTY_FUNCTION__))
3780 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3781, __PRETTY_FUNCTION__))
3781 "Cannot truncate or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3781, __PRETTY_FUNCTION__))
;
3782 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3783 return V; // No conversion
3784 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3785 return getTruncateExpr(V, Ty);
3786 return getZeroExtendExpr(V, Ty);
3787}
3788
3789const SCEV *
3790ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
3791 Type *Ty) {
3792 Type *SrcTy = V->getType();
3793 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3795, __PRETTY_FUNCTION__))
3794 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3795, __PRETTY_FUNCTION__))
3795 "Cannot truncate or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3795, __PRETTY_FUNCTION__))
;
3796 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3797 return V; // No conversion
3798 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3799 return getTruncateExpr(V, Ty);
3800 return getSignExtendExpr(V, Ty);
3801}
3802
3803const SCEV *
3804ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
3805 Type *SrcTy = V->getType();
3806 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3808, __PRETTY_FUNCTION__))
3807 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3808, __PRETTY_FUNCTION__))
3808 "Cannot noop or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3808, __PRETTY_FUNCTION__))
;
3809 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3810, __PRETTY_FUNCTION__))
3810 "getNoopOrZeroExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrZeroExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3810, __PRETTY_FUNCTION__))
;
3811 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3812 return V; // No conversion
3813 return getZeroExtendExpr(V, Ty);
3814}
3815
3816const SCEV *
3817ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
3818 Type *SrcTy = V->getType();
3819 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3821, __PRETTY_FUNCTION__))
3820 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3821, __PRETTY_FUNCTION__))
3821 "Cannot noop or sign extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3821, __PRETTY_FUNCTION__))
;
3822 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3823, __PRETTY_FUNCTION__))
3823 "getNoopOrSignExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrSignExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3823, __PRETTY_FUNCTION__))
;
3824 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3825 return V; // No conversion
3826 return getSignExtendExpr(V, Ty);
3827}
3828
3829const SCEV *
3830ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
3831 Type *SrcTy = V->getType();
3832 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3834, __PRETTY_FUNCTION__))
3833 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3834, __PRETTY_FUNCTION__))
3834 "Cannot noop or any extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3834, __PRETTY_FUNCTION__))
;
3835 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3836, __PRETTY_FUNCTION__))
3836 "getNoopOrAnyExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrAnyExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3836, __PRETTY_FUNCTION__))
;
3837 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3838 return V; // No conversion
3839 return getAnyExtendExpr(V, Ty);
3840}
3841
3842const SCEV *
3843ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
3844 Type *SrcTy = V->getType();
3845 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3847, __PRETTY_FUNCTION__))
3846 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3847, __PRETTY_FUNCTION__))
3847 "Cannot truncate or noop with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3847, __PRETTY_FUNCTION__))
;
3848 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3849, __PRETTY_FUNCTION__))
3849 "getTruncateOrNoop cannot extend!")((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
"getTruncateOrNoop cannot extend!") ? static_cast<void>
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 3849, __PRETTY_FUNCTION__))
;
3850 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3851 return V; // No conversion
3852 return getTruncateExpr(V, Ty);
3853}
3854
3855const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
3856 const SCEV *RHS) {
3857 const SCEV *PromotedLHS = LHS;
3858 const SCEV *PromotedRHS = RHS;
3859
3860 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3861 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3862 else
3863 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3864
3865 return getUMaxExpr(PromotedLHS, PromotedRHS);
3866}
3867
3868const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3869 const SCEV *RHS) {
3870 const SCEV *PromotedLHS = LHS;
3871 const SCEV *PromotedRHS = RHS;
3872
3873 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3874 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3875 else
3876 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3877
3878 return getUMinExpr(PromotedLHS, PromotedRHS);
3879}
3880
3881const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
3882 // A pointer operand may evaluate to a nonpointer expression, such as null.
3883 if (!V->getType()->isPointerTy())
3884 return V;
3885
3886 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
3887 return getPointerBase(Cast->getOperand());
3888 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
3889 const SCEV *PtrOp = nullptr;
3890 for (const SCEV *NAryOp : NAry->operands()) {
3891 if (NAryOp->getType()->isPointerTy()) {
3892 // Cannot find the base of an expression with multiple pointer operands.
3893 if (PtrOp)
3894 return V;
3895 PtrOp = NAryOp;
3896 }
3897 }
3898 if (!PtrOp)
3899 return V;
3900 return getPointerBase(PtrOp);
3901 }
3902 return V;
3903}
3904
3905/// Push users of the given Instruction onto the given Worklist.
3906static void
3907PushDefUseChildren(Instruction *I,
3908 SmallVectorImpl<Instruction *> &Worklist) {
3909 // Push the def-use children onto the Worklist stack.
3910 for (User *U : I->users())
3911 Worklist.push_back(cast<Instruction>(U));
3912}
3913
3914void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
3915 SmallVector<Instruction *, 16> Worklist;
3916 PushDefUseChildren(PN, Worklist);
3917
3918 SmallPtrSet<Instruction *, 8> Visited;
3919 Visited.insert(PN);
3920 while (!Worklist.empty()) {
3921 Instruction *I = Worklist.pop_back_val();
3922 if (!Visited.insert(I).second)
3923 continue;
3924
3925 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
3926 if (It != ValueExprMap.end()) {
3927 const SCEV *Old = It->second;
3928
3929 // Short-circuit the def-use traversal if the symbolic name
3930 // ceases to appear in expressions.
3931 if (Old != SymName && !hasOperand(Old, SymName))
3932 continue;
3933
3934 // SCEVUnknown for a PHI either means that it has an unrecognized
3935 // structure, it's a PHI that's in the progress of being computed
3936 // by createNodeForPHI, or it's a single-value PHI. In the first case,
3937 // additional loop trip count information isn't going to change anything.
3938 // In the second case, createNodeForPHI will perform the necessary
3939 // updates on its own when it gets to that point. In the third, we do
3940 // want to forget the SCEVUnknown.
3941 if (!isa<PHINode>(I) ||
3942 !isa<SCEVUnknown>(Old) ||
3943 (I != PN && Old == SymName)) {
3944 eraseValueFromMap(It->first);
3945 forgetMemoizedResults(Old);
3946 }
3947 }
3948
3949 PushDefUseChildren(I, Worklist);
3950 }
3951}
3952
3953namespace {
3954class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
3955public:
3956 static const SCEV *rewrite(const SCEV *S, const Loop *L,
3957 ScalarEvolution &SE) {
3958 SCEVInitRewriter Rewriter(L, SE);
3959 const SCEV *Result = Rewriter.visit(S);
3960 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
3961 }
3962
3963 SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
3964 : SCEVRewriteVisitor(SE), L(L), Valid(true) {}
3965
3966 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
3967 if (!SE.isLoopInvariant(Expr, L))
3968 Valid = false;
3969 return Expr;
3970 }
3971
3972 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
3973 // Only allow AddRecExprs for this loop.
3974 if (Expr->getLoop() == L)
3975 return Expr->getStart();
3976 Valid = false;
3977 return Expr;
3978 }
3979
3980 bool isValid() { return Valid; }
3981
3982private:
3983 const Loop *L;
3984 bool Valid;
3985};
3986
3987class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
3988public:
3989 static const SCEV *rewrite(const SCEV *S, const Loop *L,
3990 ScalarEvolution &SE) {
3991 SCEVShiftRewriter Rewriter(L, SE);
3992 const SCEV *Result = Rewriter.visit(S);
3993 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
3994 }
3995
3996 SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
3997 : SCEVRewriteVisitor(SE), L(L), Valid(true) {}
3998
3999 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4000 // Only allow AddRecExprs for this loop.
4001 if (!SE.isLoopInvariant(Expr, L))
4002 Valid = false;
4003 return Expr;
4004 }
4005
4006 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4007 if (Expr->getLoop() == L && Expr->isAffine())
4008 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4009 Valid = false;
4010 return Expr;
4011 }
4012 bool isValid() { return Valid; }
4013
4014private:
4015 const Loop *L;
4016 bool Valid;
4017};
4018} // end anonymous namespace
4019
4020SCEV::NoWrapFlags
4021ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4022 if (!AR->isAffine())
4023 return SCEV::FlagAnyWrap;
4024
4025 typedef OverflowingBinaryOperator OBO;
4026 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4027
4028 if (!AR->hasNoSignedWrap()) {
4029 ConstantRange AddRecRange = getSignedRange(AR);
4030 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4031
4032 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4033 Instruction::Add, IncRange, OBO::NoSignedWrap);
4034 if (NSWRegion.contains(AddRecRange))
4035 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4036 }
4037
4038 if (!AR->hasNoUnsignedWrap()) {
4039 ConstantRange AddRecRange = getUnsignedRange(AR);
4040 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4041
4042 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4043 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4044 if (NUWRegion.contains(AddRecRange))
4045 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4046 }
4047
4048 return Result;
4049}
4050
4051namespace {
4052/// Represents an abstract binary operation. This may exist as a
4053/// normal instruction or constant expression, or may have been
4054/// derived from an expression tree.
4055struct BinaryOp {
4056 unsigned Opcode;
4057 Value *LHS;
4058 Value *RHS;
4059 bool IsNSW;
4060 bool IsNUW;
4061
4062 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4063 /// constant expression.
4064 Operator *Op;
4065
4066 explicit BinaryOp(Operator *Op)
4067 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4068 IsNSW(false), IsNUW(false), Op(Op) {
4069 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4070 IsNSW = OBO->hasNoSignedWrap();
4071 IsNUW = OBO->hasNoUnsignedWrap();
4072 }
4073 }
4074
4075 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4076 bool IsNUW = false)
4077 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW),
4078 Op(nullptr) {}
4079};
4080}
4081
4082
4083/// Try to map \p V into a BinaryOp, and return \c None on failure.
4084static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4085 auto *Op = dyn_cast<Operator>(V);
4086 if (!Op)
4087 return None;
4088
4089 // Implementation detail: all the cleverness here should happen without
4090 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4091 // SCEV expressions when possible, and we should not break that.
4092
4093 switch (Op->getOpcode()) {
4094 case Instruction::Add:
4095 case Instruction::Sub:
4096 case Instruction::Mul:
4097 case Instruction::UDiv:
4098 case Instruction::And:
4099 case Instruction::Or:
4100 case Instruction::AShr:
4101 case Instruction::Shl:
4102 return BinaryOp(Op);
4103
4104 case Instruction::Xor:
4105 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4106 // If the RHS of the xor is a signmask, then this is just an add.
4107 // Instcombine turns add of signmask into xor as a strength reduction step.
4108 if (RHSC->getValue().isSignMask())
4109 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4110 return BinaryOp(Op);
4111
4112 case Instruction::LShr:
4113 // Turn logical shift right of a constant into a unsigned divide.
4114 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4115 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4116
4117 // If the shift count is not less than the bitwidth, the result of
4118 // the shift is undefined. Don't try to analyze it, because the
4119 // resolution chosen here may differ from the resolution chosen in
4120 // other parts of the compiler.
4121 if (SA->getValue().ult(BitWidth)) {
4122 Constant *X =
4123 ConstantInt::get(SA->getContext(),
4124 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4125 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4126 }
4127 }
4128 return BinaryOp(Op);
4129
4130 case Instruction::ExtractValue: {
4131 auto *EVI = cast<ExtractValueInst>(Op);
4132 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
4133 break;
4134
4135 auto *CI = dyn_cast<CallInst>(EVI->getAggregateOperand());
4136 if (!CI)
4137 break;
4138
4139 if (auto *F = CI->getCalledFunction())
4140 switch (F->getIntrinsicID()) {
4141 case Intrinsic::sadd_with_overflow:
4142 case Intrinsic::uadd_with_overflow: {
4143 if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT))
4144 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4145 CI->getArgOperand(1));
4146
4147 // Now that we know that all uses of the arithmetic-result component of
4148 // CI are guarded by the overflow check, we can go ahead and pretend
4149 // that the arithmetic is non-overflowing.
4150 if (F->getIntrinsicID() == Intrinsic::sadd_with_overflow)
4151 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4152 CI->getArgOperand(1), /* IsNSW = */ true,
4153 /* IsNUW = */ false);
4154 else
4155 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4156 CI->getArgOperand(1), /* IsNSW = */ false,
4157 /* IsNUW*/ true);
4158 }
4159
4160 case Intrinsic::ssub_with_overflow:
4161 case Intrinsic::usub_with_overflow:
4162 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4163 CI->getArgOperand(1));
4164
4165 case Intrinsic::smul_with_overflow:
4166 case Intrinsic::umul_with_overflow:
4167 return BinaryOp(Instruction::Mul, CI->getArgOperand(0),
4168 CI->getArgOperand(1));
4169 default:
4170 break;
4171 }
4172 }
4173
4174 default:
4175 break;
4176 }
4177
4178 return None;
4179}
4180
4181/// A helper function for createAddRecFromPHI to handle simple cases.
4182///
4183/// This function tries to find an AddRec expression for the simplest (yet most
4184/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
4185/// If it fails, createAddRecFromPHI will use a more general, but slow,
4186/// technique for finding the AddRec expression.
4187const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
4188 Value *BEValueV,
4189 Value *StartValueV) {
4190 const Loop *L = LI.getLoopFor(PN->getParent());
4191 assert(L && L->getHeader() == PN->getParent())((L && L->getHeader() == PN->getParent()) ? static_cast
<void> (0) : __assert_fail ("L && L->getHeader() == PN->getParent()"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4191, __PRETTY_FUNCTION__))
;
4192 assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> (
0) : __assert_fail ("BEValueV && StartValueV", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4192, __PRETTY_FUNCTION__))
;
4193
4194 auto BO = MatchBinaryOp(BEValueV, DT);
4195 if (!BO)
4196 return nullptr;
4197
4198 if (BO->Opcode != Instruction::Add)
4199 return nullptr;
4200
4201 const SCEV *Accum = nullptr;
4202 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
4203 Accum = getSCEV(BO->RHS);
4204 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
4205 Accum = getSCEV(BO->LHS);
4206
4207 if (!Accum)
4208 return nullptr;
4209
4210 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4211 if (BO->IsNUW)
4212 Flags = setFlags(Flags, SCEV::FlagNUW);
4213 if (BO->IsNSW)
4214 Flags = setFlags(Flags, SCEV::FlagNSW);
4215
4216 const SCEV *StartVal = getSCEV(StartValueV);
4217 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4218
4219 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4220
4221 // We can add Flags to the post-inc expression only if we
4222 // know that it is *undefined behavior* for BEValueV to
4223 // overflow.
4224 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4225 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4226 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4227
4228 return PHISCEV;
4229}
4230
4231const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
4232 const Loop *L = LI.getLoopFor(PN->getParent());
4233 if (!L || L->getHeader() != PN->getParent())
4234 return nullptr;
4235
4236 // The loop may have multiple entrances or multiple exits; we can analyze
4237 // this phi as an addrec if it has a unique entry value and a unique
4238 // backedge value.
4239 Value *BEValueV = nullptr, *StartValueV = nullptr;
4240 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4241 Value *V = PN->getIncomingValue(i);
4242 if (L->contains(PN->getIncomingBlock(i))) {
4243 if (!BEValueV) {
4244 BEValueV = V;
4245 } else if (BEValueV != V) {
4246 BEValueV = nullptr;
4247 break;
4248 }
4249 } else if (!StartValueV) {
4250 StartValueV = V;
4251 } else if (StartValueV != V) {
4252 StartValueV = nullptr;
4253 break;
4254 }
4255 }
4256 if (!BEValueV || !StartValueV)
4257 return nullptr;
4258
4259 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4260, __PRETTY_FUNCTION__))
4260 "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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4260, __PRETTY_FUNCTION__))
;
4261
4262 // First, try to find AddRec expression without creating a fictituos symbolic
4263 // value for PN.
4264 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
4265 return S;
4266
4267 // Handle PHI node value symbolically.
4268 const SCEV *SymbolicName = getUnknown(PN);
4269 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
4270
4271 // Using this symbolic name for the PHI, analyze the value coming around
4272 // the back-edge.
4273 const SCEV *BEValue = getSCEV(BEValueV);
4274
4275 // NOTE: If BEValue is loop invariant, we know that the PHI node just
4276 // has a special value for the first iteration of the loop.
4277
4278 // If the value coming around the backedge is an add with the symbolic
4279 // value we just inserted, then we found a simple induction variable!
4280 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
4281 // If there is a single occurrence of the symbolic value, replace it
4282 // with a recurrence.
4283 unsigned FoundIndex = Add->getNumOperands();
4284 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4285 if (Add->getOperand(i) == SymbolicName)
4286 if (FoundIndex == e) {
4287 FoundIndex = i;
4288 break;
4289 }
4290
4291 if (FoundIndex != Add->getNumOperands()) {
4292 // Create an add with everything but the specified operand.
4293 SmallVector<const SCEV *, 8> Ops;
4294 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4295 if (i != FoundIndex)
4296 Ops.push_back(Add->getOperand(i));
4297 const SCEV *Accum = getAddExpr(Ops);
4298
4299 // This is not a valid addrec if the step amount is varying each
4300 // loop iteration, but is not itself an addrec in this loop.
4301 if (isLoopInvariant(Accum, L) ||
4302 (isa<SCEVAddRecExpr>(Accum) &&
4303 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
4304 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4305
4306 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
4307 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
4308 if (BO->IsNUW)
4309 Flags = setFlags(Flags, SCEV::FlagNUW);
4310 if (BO->IsNSW)
4311 Flags = setFlags(Flags, SCEV::FlagNSW);
4312 }
4313 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
4314 // If the increment is an inbounds GEP, then we know the address
4315 // space cannot be wrapped around. We cannot make any guarantee
4316 // about signed or unsigned overflow because pointers are
4317 // unsigned but we may have a negative index from the base
4318 // pointer. We can guarantee that no unsigned wrap occurs if the
4319 // indices form a positive value.
4320 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
4321 Flags = setFlags(Flags, SCEV::FlagNW);
4322
4323 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
4324 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
4325 Flags = setFlags(Flags, SCEV::FlagNUW);
4326 }
4327
4328 // We cannot transfer nuw and nsw flags from subtraction
4329 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
4330 // for instance.
4331 }
4332
4333 const SCEV *StartVal = getSCEV(StartValueV);
4334 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4335
4336 // Okay, for the entire analysis of this edge we assumed the PHI
4337 // to be symbolic. We now need to go back and purge all of the
4338 // entries for the scalars that use the symbolic expression.
4339 forgetSymbolicName(PN, SymbolicName);
4340 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4341
4342 // We can add Flags to the post-inc expression only if we
4343 // know that it is *undefined behavior* for BEValueV to
4344 // overflow.
4345 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4346 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4347 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4348
4349 return PHISCEV;
4350 }
4351 }
4352 } else {
4353 // Otherwise, this could be a loop like this:
4354 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
4355 // In this case, j = {1,+,1} and BEValue is j.
4356 // Because the other in-value of i (0) fits the evolution of BEValue
4357 // i really is an addrec evolution.
4358 //
4359 // We can generalize this saying that i is the shifted value of BEValue
4360 // by one iteration:
4361 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
4362 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
4363 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this);
4364 if (Shifted != getCouldNotCompute() &&
4365 Start != getCouldNotCompute()) {
4366 const SCEV *StartVal = getSCEV(StartValueV);
4367 if (Start == StartVal) {
4368 // Okay, for the entire analysis of this edge we assumed the PHI
4369 // to be symbolic. We now need to go back and purge all of the
4370 // entries for the scalars that use the symbolic expression.
4371 forgetSymbolicName(PN, SymbolicName);
4372 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
4373 return Shifted;
4374 }
4375 }
4376 }
4377
4378 // Remove the temporary PHI node SCEV that has been inserted while intending
4379 // to create an AddRecExpr for this PHI node. We can not keep this temporary
4380 // as it will prevent later (possibly simpler) SCEV expressions to be added
4381 // to the ValueExprMap.
4382 eraseValueFromMap(PN);
4383
4384 return nullptr;
4385}
4386
4387// Checks if the SCEV S is available at BB. S is considered available at BB
4388// if S can be materialized at BB without introducing a fault.
4389static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
4390 BasicBlock *BB) {
4391 struct CheckAvailable {
4392 bool TraversalDone = false;
4393 bool Available = true;
4394
4395 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
4396 BasicBlock *BB = nullptr;
4397 DominatorTree &DT;
4398
4399 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
4400 : L(L), BB(BB), DT(DT) {}
4401
4402 bool setUnavailable() {
4403 TraversalDone = true;
4404 Available = false;
4405 return false;
4406 }
4407
4408 bool follow(const SCEV *S) {
4409 switch (S->getSCEVType()) {
4410 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
4411 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
4412 // These expressions are available if their operand(s) is/are.
4413 return true;
4414
4415 case scAddRecExpr: {
4416 // We allow add recurrences that are on the loop BB is in, or some
4417 // outer loop. This guarantees availability because the value of the
4418 // add recurrence at BB is simply the "current" value of the induction
4419 // variable. We can relax this in the future; for instance an add
4420 // recurrence on a sibling dominating loop is also available at BB.
4421 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
4422 if (L && (ARLoop == L || ARLoop->contains(L)))
4423 return true;
4424
4425 return setUnavailable();
4426 }
4427
4428 case scUnknown: {
4429 // For SCEVUnknown, we check for simple dominance.
4430 const auto *SU = cast<SCEVUnknown>(S);
4431 Value *V = SU->getValue();
4432
4433 if (isa<Argument>(V))
4434 return false;
4435
4436 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
4437 return false;
4438
4439 return setUnavailable();
4440 }
4441
4442 case scUDivExpr:
4443 case scCouldNotCompute:
4444 // We do not try to smart about these at all.
4445 return setUnavailable();
4446 }
4447 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4447)
;
4448 }
4449
4450 bool isDone() { return TraversalDone; }
4451 };
4452
4453 CheckAvailable CA(L, BB, DT);
4454 SCEVTraversal<CheckAvailable> ST(CA);
4455
4456 ST.visitAll(S);
4457 return CA.Available;
4458}
4459
4460// Try to match a control flow sequence that branches out at BI and merges back
4461// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
4462// match.
4463static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
4464 Value *&C, Value *&LHS, Value *&RHS) {
4465 C = BI->getCondition();
4466
4467 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
4468 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
4469
4470 if (!LeftEdge.isSingleEdge())
4471 return false;
4472
4473 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()\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4473, __PRETTY_FUNCTION__))
;
4474
4475 Use &LeftUse = Merge->getOperandUse(0);
4476 Use &RightUse = Merge->getOperandUse(1);
4477
4478 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
4479 LHS = LeftUse;
4480 RHS = RightUse;
4481 return true;
4482 }
4483
4484 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
4485 LHS = RightUse;
4486 RHS = LeftUse;
4487 return true;
4488 }
4489
4490 return false;
4491}
4492
4493const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
4494 auto IsReachable =
4495 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
4496 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
4497 const Loop *L = LI.getLoopFor(PN->getParent());
4498
4499 // We don't want to break LCSSA, even in a SCEV expression tree.
4500 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
4501 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
4502 return nullptr;
4503
4504 // Try to match
4505 //
4506 // br %cond, label %left, label %right
4507 // left:
4508 // br label %merge
4509 // right:
4510 // br label %merge
4511 // merge:
4512 // V = phi [ %x, %left ], [ %y, %right ]
4513 //
4514 // as "select %cond, %x, %y"
4515
4516 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
4517 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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4517, __PRETTY_FUNCTION__))
;
4518
4519 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
4520 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
4521
4522 if (BI && BI->isConditional() &&
4523 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
4524 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
4525 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
4526 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
4527 }
4528
4529 return nullptr;
4530}
4531
4532const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
4533 if (const SCEV *S = createAddRecFromPHI(PN))
4534 return S;
4535
4536 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
4537 return S;
4538
4539 // If the PHI has a single incoming value, follow that value, unless the
4540 // PHI's incoming blocks are in a different loop, in which case doing so
4541 // risks breaking LCSSA form. Instcombine would normally zap these, but
4542 // it doesn't have DominatorTree information, so it may miss cases.
4543 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
4544 if (LI.replacementPreservesLCSSAForm(PN, V))
4545 return getSCEV(V);
4546
4547 // If it's not a loop phi, we can't handle it yet.
4548 return getUnknown(PN);
4549}
4550
4551const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
4552 Value *Cond,
4553 Value *TrueVal,
4554 Value *FalseVal) {
4555 // Handle "constant" branch or select. This can occur for instance when a
4556 // loop pass transforms an inner loop and moves on to process the outer loop.
4557 if (auto *CI = dyn_cast<ConstantInt>(Cond))
4558 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
4559
4560 // Try to match some simple smax or umax patterns.
4561 auto *ICI = dyn_cast<ICmpInst>(Cond);
4562 if (!ICI)
4563 return getUnknown(I);
4564
4565 Value *LHS = ICI->getOperand(0);
4566 Value *RHS = ICI->getOperand(1);
4567
4568 switch (ICI->getPredicate()) {
4569 case ICmpInst::ICMP_SLT:
4570 case ICmpInst::ICMP_SLE:
4571 std::swap(LHS, RHS);
4572 LLVM_FALLTHROUGH[[clang::fallthrough]];
4573 case ICmpInst::ICMP_SGT:
4574 case ICmpInst::ICMP_SGE:
4575 // a >s b ? a+x : b+x -> smax(a, b)+x
4576 // a >s b ? b+x : a+x -> smin(a, b)+x
4577 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
4578 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
4579 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
4580 const SCEV *LA = getSCEV(TrueVal);
4581 const SCEV *RA = getSCEV(FalseVal);
4582 const SCEV *LDiff = getMinusSCEV(LA, LS);
4583 const SCEV *RDiff = getMinusSCEV(RA, RS);
4584 if (LDiff == RDiff)
4585 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
4586 LDiff = getMinusSCEV(LA, RS);
4587 RDiff = getMinusSCEV(RA, LS);
4588 if (LDiff == RDiff)
4589 return getAddExpr(getSMinExpr(LS, RS), LDiff);
4590 }
4591 break;
4592 case ICmpInst::ICMP_ULT:
4593 case ICmpInst::ICMP_ULE:
4594 std::swap(LHS, RHS);
4595 LLVM_FALLTHROUGH[[clang::fallthrough]];
4596 case ICmpInst::ICMP_UGT:
4597 case ICmpInst::ICMP_UGE:
4598 // a >u b ? a+x : b+x -> umax(a, b)+x
4599 // a >u b ? b+x : a+x -> umin(a, b)+x
4600 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
4601 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4602 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
4603 const SCEV *LA = getSCEV(TrueVal);
4604 const SCEV *RA = getSCEV(FalseVal);
4605 const SCEV *LDiff = getMinusSCEV(LA, LS);
4606 const SCEV *RDiff = getMinusSCEV(RA, RS);
4607 if (LDiff == RDiff)
4608 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
4609 LDiff = getMinusSCEV(LA, RS);
4610 RDiff = getMinusSCEV(RA, LS);
4611 if (LDiff == RDiff)
4612 return getAddExpr(getUMinExpr(LS, RS), LDiff);
4613 }
4614 break;
4615 case ICmpInst::ICMP_NE:
4616 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
4617 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
4618 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
4619 const SCEV *One = getOne(I->getType());
4620 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4621 const SCEV *LA = getSCEV(TrueVal);
4622 const SCEV *RA = getSCEV(FalseVal);
4623 const SCEV *LDiff = getMinusSCEV(LA, LS);
4624 const SCEV *RDiff = getMinusSCEV(RA, One);
4625 if (LDiff == RDiff)
4626 return getAddExpr(getUMaxExpr(One, LS), LDiff);
4627 }
4628 break;
4629 case ICmpInst::ICMP_EQ:
4630 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
4631 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
4632 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
4633 const SCEV *One = getOne(I->getType());
4634 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4635 const SCEV *LA = getSCEV(TrueVal);
4636 const SCEV *RA = getSCEV(FalseVal);
4637 const SCEV *LDiff = getMinusSCEV(LA, One);
4638 const SCEV *RDiff = getMinusSCEV(RA, LS);
4639 if (LDiff == RDiff)
4640 return getAddExpr(getUMaxExpr(One, LS), LDiff);
4641 }
4642 break;
4643 default:
4644 break;
4645 }
4646
4647 return getUnknown(I);
4648}
4649
4650/// Expand GEP instructions into add and multiply operations. This allows them
4651/// to be analyzed by regular SCEV code.
4652const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
4653 // Don't attempt to analyze GEPs over unsized objects.
4654 if (!GEP->getSourceElementType()->isSized())
4655 return getUnknown(GEP);
4656
4657 SmallVector<const SCEV *, 4> IndexExprs;
4658 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
4659 IndexExprs.push_back(getSCEV(*Index));
4660 return getGEPExpr(GEP, IndexExprs);
4661}
4662
4663uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
4664 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
4665 return C->getAPInt().countTrailingZeros();
4666
4667 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
4668 return std::min(GetMinTrailingZeros(T->getOperand()),
4669 (uint32_t)getTypeSizeInBits(T->getType()));
4670
4671 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
4672 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
4673 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
4674 ? getTypeSizeInBits(E->getType())
4675 : OpRes;
4676 }
4677
4678 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
4679 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
4680 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
4681 ? getTypeSizeInBits(E->getType())
4682 : OpRes;
4683 }
4684
4685 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
4686 // The result is the min of all operands results.
4687 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
4688 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
4689 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
4690 return MinOpRes;
4691 }
4692
4693 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
4694 // The result is the sum of all operands results.
4695 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
4696 uint32_t BitWidth = getTypeSizeInBits(M->getType());
4697 for (unsigned i = 1, e = M->getNumOperands();
4698 SumOpRes != BitWidth && i != e; ++i)
4699 SumOpRes =
4700 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
4701 return SumOpRes;
4702 }
4703
4704 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
4705 // The result is the min of all operands results.
4706 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
4707 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
4708 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
4709 return MinOpRes;
4710 }
4711
4712 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
4713 // The result is the min of all operands results.
4714 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
4715 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
4716 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
4717 return MinOpRes;
4718 }
4719
4720 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
4721 // The result is the min of all operands results.
4722 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
4723 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
4724 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
4725 return MinOpRes;
4726 }
4727
4728 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
4729 // For a SCEVUnknown, ask ValueTracking.
4730 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
4731 return Known.countMinTrailingZeros();
4732 }
4733
4734 // SCEVUDivExpr
4735 return 0;
4736}
4737
4738uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
4739 auto I = MinTrailingZerosCache.find(S);
4740 if (I != MinTrailingZerosCache.end())
4741 return I->second;
4742
4743 uint32_t Result = GetMinTrailingZerosImpl(S);
4744 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
4745 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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4745, __PRETTY_FUNCTION__))
;
4746 return InsertPair.first->second;
4747}
4748
4749/// Helper method to assign a range to V from metadata present in the IR.
4750static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
4751 if (Instruction *I = dyn_cast<Instruction>(V))
4752 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
4753 return getConstantRangeFromMetadata(*MD);
4754
4755 return None;
4756}
4757
4758/// Determine the range for a particular SCEV. If SignHint is
4759/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
4760/// with a "cleaner" unsigned (resp. signed) representation.
4761const ConstantRange &
4762ScalarEvolution::getRangeRef(const SCEV *S,
4763 ScalarEvolution::RangeSignHint SignHint) {
4764 DenseMap<const SCEV *, ConstantRange> &Cache =
4765 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
4766 : SignedRanges;
4767
4768 // See if we've computed this range already.
4769 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
4770 if (I != Cache.end())
4771 return I->second;
4772
4773 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
4774 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
4775
4776 unsigned BitWidth = getTypeSizeInBits(S->getType());
4777 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
4778
4779 // If the value has known zeros, the maximum value will have those known zeros
4780 // as well.
4781 uint32_t TZ = GetMinTrailingZeros(S);
4782 if (TZ != 0) {
4783 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
4784 ConservativeResult =
4785 ConstantRange(APInt::getMinValue(BitWidth),
4786 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
4787 else
4788 ConservativeResult = ConstantRange(
4789 APInt::getSignedMinValue(BitWidth),
4790 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
4791 }
4792
4793 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
4794 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
4795 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
4796 X = X.add(getRangeRef(Add->getOperand(i), SignHint));
4797 return setRange(Add, SignHint, ConservativeResult.intersectWith(X));
4798 }
4799
4800 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
4801 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
4802 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
4803 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
4804 return setRange(Mul, SignHint, ConservativeResult.intersectWith(X));
4805 }
4806
4807 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
4808 ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint);
4809 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
4810 X = X.smax(getRangeRef(SMax->getOperand(i), SignHint));
4811 return setRange(SMax, SignHint, ConservativeResult.intersectWith(X));
4812 }
4813
4814 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
4815 ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
4816 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
4817 X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
4818 return setRange(UMax, SignHint, ConservativeResult.intersectWith(X));
4819 }
4820
4821 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
4822 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
4823 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
4824 return setRange(UDiv, SignHint,
4825 ConservativeResult.intersectWith(X.udiv(Y)));
4826 }
4827
4828 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
4829 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
4830 return setRange(ZExt, SignHint,
4831 ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
4832 }
4833
4834 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
4835 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
4836 return setRange(SExt, SignHint,
4837 ConservativeResult.intersectWith(X.signExtend(BitWidth)));
4838 }
4839
4840 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
4841 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
4842 return setRange(Trunc, SignHint,
4843 ConservativeResult.intersectWith(X.truncate(BitWidth)));
4844 }
4845
4846 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
4847 // If there's no unsigned wrap, the value will never be less than its
4848 // initial value.
4849 if (AddRec->hasNoUnsignedWrap())
4850 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
4851 if (!C->getValue()->isZero())
4852 ConservativeResult = ConservativeResult.intersectWith(
4853 ConstantRange(C->getAPInt(), APInt(BitWidth, 0)));
4854
4855 // If there's no signed wrap, and all the operands have the same sign or
4856 // zero, the value won't ever change sign.
4857 if (AddRec->hasNoSignedWrap()) {
4858 bool AllNonNeg = true;
4859 bool AllNonPos = true;
4860 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
4861 if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
4862 if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
4863 }
4864 if (AllNonNeg)
4865 ConservativeResult = ConservativeResult.intersectWith(
4866 ConstantRange(APInt(BitWidth, 0),
4867 APInt::getSignedMinValue(BitWidth)));
4868 else if (AllNonPos)
4869 ConservativeResult = ConservativeResult.intersectWith(
4870 ConstantRange(APInt::getSignedMinValue(BitWidth),
4871 APInt(BitWidth, 1)));
4872 }
4873
4874 // TODO: non-affine addrec
4875 if (AddRec->isAffine()) {
4876 const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
4877 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
4878 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
4879 auto RangeFromAffine = getRangeForAffineAR(
4880 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
4881 BitWidth);
4882 if (!RangeFromAffine.isFullSet())
4883 ConservativeResult =
4884 ConservativeResult.intersectWith(RangeFromAffine);
4885
4886 auto RangeFromFactoring = getRangeViaFactoring(
4887 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
4888 BitWidth);
4889 if (!RangeFromFactoring.isFullSet())
4890 ConservativeResult =
4891 ConservativeResult.intersectWith(RangeFromFactoring);
4892 }
4893 }
4894
4895 return setRange(AddRec, SignHint, std::move(ConservativeResult));
4896 }
4897
4898 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
4899 // Check if the IR explicitly contains !range metadata.
4900 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
4901 if (MDRange.hasValue())
4902 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue());
4903
4904 // Split here to avoid paying the compile-time cost of calling both
4905 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
4906 // if needed.
4907 const DataLayout &DL = getDataLayout();
4908 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
4909 // For a SCEVUnknown, ask ValueTracking.
4910 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
4911 if (Known.One != ~Known.Zero + 1)
4912 ConservativeResult =
4913 ConservativeResult.intersectWith(ConstantRange(Known.One,
4914 ~Known.Zero + 1));
4915 } else {
4916 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4917, __PRETTY_FUNCTION__))
4917 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 4917, __PRETTY_FUNCTION__))
;
4918 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
4919 if (NS > 1)
4920 ConservativeResult = ConservativeResult.intersectWith(
4921 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
4922 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1));
4923 }
4924
4925 return setRange(U, SignHint, std::move(ConservativeResult));
4926 }
4927
4928 return setRange(S, SignHint, std::move(ConservativeResult));
4929}
4930
4931// Given a StartRange, Step and MaxBECount for an expression compute a range of
4932// values that the expression can take. Initially, the expression has a value
4933// from StartRange and then is changed by Step up to MaxBECount times. Signed
4934// argument defines if we treat Step as signed or unsigned.
4935static ConstantRange getRangeForAffineARHelper(APInt Step,
4936 const ConstantRange &StartRange,
4937 const APInt &MaxBECount,
4938 unsigned BitWidth, bool Signed) {
4939 // If either Step or MaxBECount is 0, then the expression won't change, and we
4940 // just need to return the initial range.
4941 if (Step == 0 || MaxBECount == 0)
4942 return StartRange;
4943
4944 // If we don't know anything about the initial value (i.e. StartRange is
4945 // FullRange), then we don't know anything about the final range either.
4946 // Return FullRange.
4947 if (StartRange.isFullSet())
4948 return ConstantRange(BitWidth, /* isFullSet = */ true);
4949
4950 // If Step is signed and negative, then we use its absolute value, but we also
4951 // note that we're moving in the opposite direction.
4952 bool Descending = Signed && Step.isNegative();
4953
4954 if (Signed)
4955 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
4956 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
4957 // This equations hold true due to the well-defined wrap-around behavior of
4958 // APInt.
4959 Step = Step.abs();
4960
4961 // Check if Offset is more than full span of BitWidth. If it is, the
4962 // expression is guaranteed to overflow.
4963 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
4964 return ConstantRange(BitWidth, /* isFullSet = */ true);
4965
4966 // Offset is by how much the expression can change. Checks above guarantee no
4967 // overflow here.
4968 APInt Offset = Step * MaxBECount;
4969
4970 // Minimum value of the final range will match the minimal value of StartRange
4971 // if the expression is increasing and will be decreased by Offset otherwise.
4972 // Maximum value of the final range will match the maximal value of StartRange
4973 // if the expression is decreasing and will be increased by Offset otherwise.
4974 APInt StartLower = StartRange.getLower();
4975 APInt StartUpper = StartRange.getUpper() - 1;
4976 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
4977 : (StartUpper + std::move(Offset));
4978
4979 // It's possible that the new minimum/maximum value will fall into the initial
4980 // range (due to wrap around). This means that the expression can take any
4981 // value in this bitwidth, and we have to return full range.
4982 if (StartRange.contains(MovedBoundary))
4983 return ConstantRange(BitWidth, /* isFullSet = */ true);
4984
4985 APInt NewLower =
4986 Descending ? std::move(MovedBoundary) : std::move(StartLower);
4987 APInt NewUpper =
4988 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
4989 NewUpper += 1;
4990
4991 // If we end up with full range, return a proper full range.
4992 if (NewLower == NewUpper)
4993 return ConstantRange(BitWidth, /* isFullSet = */ true);
4994
4995 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
4996 return ConstantRange(std::move(NewLower), std::move(NewUpper));
4997}
4998
4999ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
5000 const SCEV *Step,
5001 const SCEV *MaxBECount,
5002 unsigned BitWidth) {
5003 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5005, __PRETTY_FUNCTION__))
5004 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5005, __PRETTY_FUNCTION__))
5005 "Precondition!")((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5005, __PRETTY_FUNCTION__))
;
5006
5007 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
5008 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
5009
5010 // First, consider step signed.
5011 ConstantRange StartSRange = getSignedRange(Start);
5012 ConstantRange StepSRange = getSignedRange(Step);
5013
5014 // If Step can be both positive and negative, we need to find ranges for the
5015 // maximum absolute step values in both directions and union them.
5016 ConstantRange SR =
5017 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
5018 MaxBECountValue, BitWidth, /* Signed = */ true);
5019 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
5020 StartSRange, MaxBECountValue,
5021 BitWidth, /* Signed = */ true));
5022
5023 // Next, consider step unsigned.
5024 ConstantRange UR = getRangeForAffineARHelper(
5025 getUnsignedRangeMax(Step), getUnsignedRange(Start),
5026 MaxBECountValue, BitWidth, /* Signed = */ false);
5027
5028 // Finally, intersect signed and unsigned ranges.
5029 return SR.intersectWith(UR);
5030}
5031
5032ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
5033 const SCEV *Step,
5034 const SCEV *MaxBECount,
5035 unsigned BitWidth) {
5036 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
5037 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
5038
5039 struct SelectPattern {
5040 Value *Condition = nullptr;
5041 APInt TrueValue;
5042 APInt FalseValue;
5043
5044 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
5045 const SCEV *S) {
5046 Optional<unsigned> CastOp;
5047 APInt Offset(BitWidth, 0);
5048
5049 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5050, __PRETTY_FUNCTION__))
5050 "Should be!")((SE.getTypeSizeInBits(S->getType()) == BitWidth &&
"Should be!") ? static_cast<void> (0) : __assert_fail (
"SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5050, __PRETTY_FUNCTION__))
;
5051
5052 // Peel off a constant offset:
5053 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
5054 // In the future we could consider being smarter here and handle
5055 // {Start+Step,+,Step} too.
5056 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
5057 return;
5058
5059 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
5060 S = SA->getOperand(1);
5061 }
5062
5063 // Peel off a cast operation
5064 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
5065 CastOp = SCast->getSCEVType();
5066 S = SCast->getOperand();
5067 }
5068
5069 using namespace llvm::PatternMatch;
5070
5071 auto *SU = dyn_cast<SCEVUnknown>(S);
5072 const APInt *TrueVal, *FalseVal;
5073 if (!SU ||
5074 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
5075 m_APInt(FalseVal)))) {
5076 Condition = nullptr;
5077 return;
5078 }
5079
5080 TrueValue = *TrueVal;
5081 FalseValue = *FalseVal;
5082
5083 // Re-apply the cast we peeled off earlier
5084 if (CastOp.hasValue())
5085 switch (*CastOp) {
5086 default:
5087 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5087)
;
5088
5089 case scTruncate:
5090 TrueValue = TrueValue.trunc(BitWidth);
5091 FalseValue = FalseValue.trunc(BitWidth);
5092 break;
5093 case scZeroExtend:
5094 TrueValue = TrueValue.zext(BitWidth);
5095 FalseValue = FalseValue.zext(BitWidth);
5096 break;
5097 case scSignExtend:
5098 TrueValue = TrueValue.sext(BitWidth);
5099 FalseValue = FalseValue.sext(BitWidth);
5100 break;
5101 }
5102
5103 // Re-apply the constant offset we peeled off earlier
5104 TrueValue += Offset;
5105 FalseValue += Offset;
5106 }
5107
5108 bool isRecognized() { return Condition != nullptr; }
5109 };
5110
5111 SelectPattern StartPattern(*this, BitWidth, Start);
5112 if (!StartPattern.isRecognized())
5113 return ConstantRange(BitWidth, /* isFullSet = */ true);
5114
5115 SelectPattern StepPattern(*this, BitWidth, Step);
5116 if (!StepPattern.isRecognized())
5117 return ConstantRange(BitWidth, /* isFullSet = */ true);
5118
5119 if (StartPattern.Condition != StepPattern.Condition) {
5120 // We don't handle this case today; but we could, by considering four
5121 // possibilities below instead of two. I'm not sure if there are cases where
5122 // that will help over what getRange already does, though.
5123 return ConstantRange(BitWidth, /* isFullSet = */ true);
5124 }
5125
5126 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
5127 // construct arbitrary general SCEV expressions here. This function is called
5128 // from deep in the call stack, and calling getSCEV (on a sext instruction,
5129 // say) can end up caching a suboptimal value.
5130
5131 // FIXME: without the explicit `this` receiver below, MSVC errors out with
5132 // C2352 and C2512 (otherwise it isn't needed).
5133
5134 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
5135 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
5136 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
5137 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
5138
5139 ConstantRange TrueRange =
5140 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
5141 ConstantRange FalseRange =
5142 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
5143
5144 return TrueRange.unionWith(FalseRange);
5145}
5146
5147SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
5148 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
5149 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
5150
5151 // Return early if there are no flags to propagate to the SCEV.
5152 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5153 if (BinOp->hasNoUnsignedWrap())
5154 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
5155 if (BinOp->hasNoSignedWrap())
5156 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
5157 if (Flags == SCEV::FlagAnyWrap)
5158 return SCEV::FlagAnyWrap;
5159
5160 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
5161}
5162
5163bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
5164 // Here we check that I is in the header of the innermost loop containing I,
5165 // since we only deal with instructions in the loop header. The actual loop we
5166 // need to check later will come from an add recurrence, but getting that
5167 // requires computing the SCEV of the operands, which can be expensive. This
5168 // check we can do cheaply to rule out some cases early.
5169 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
5170 if (InnermostContainingLoop == nullptr ||
5171 InnermostContainingLoop->getHeader() != I->getParent())
5172 return false;
5173
5174 // Only proceed if we can prove that I does not yield poison.
5175 if (!programUndefinedIfFullPoison(I))
5176 return false;
5177
5178 // At this point we know that if I is executed, then it does not wrap
5179 // according to at least one of NSW or NUW. If I is not executed, then we do
5180 // not know if the calculation that I represents would wrap. Multiple
5181 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
5182 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
5183 // derived from other instructions that map to the same SCEV. We cannot make
5184 // that guarantee for cases where I is not executed. So we need to find the
5185 // loop that I is considered in relation to and prove that I is executed for
5186 // every iteration of that loop. That implies that the value that I
5187 // calculates does not wrap anywhere in the loop, so then we can apply the
5188 // flags to the SCEV.
5189 //
5190 // We check isLoopInvariant to disambiguate in case we are adding recurrences
5191 // from different loops, so that we know which loop to prove that I is
5192 // executed in.
5193 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
5194 // I could be an extractvalue from a call to an overflow intrinsic.
5195 // TODO: We can do better here in some cases.
5196 if (!isSCEVable(I->getOperand(OpIndex)->getType()))
5197 return false;
5198 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
5199 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
5200 bool AllOtherOpsLoopInvariant = true;
5201 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
5202 ++OtherOpIndex) {
5203 if (OtherOpIndex != OpIndex) {
5204 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
5205 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
5206 AllOtherOpsLoopInvariant = false;
5207 break;
5208 }
5209 }
5210 }
5211 if (AllOtherOpsLoopInvariant &&
5212 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
5213 return true;
5214 }
5215 }
5216 return false;
5217}
5218
5219bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) {
5220 // If we know that \c I can never be poison period, then that's enough.
5221 if (isSCEVExprNeverPoison(I))
5222 return true;
5223
5224 // For an add recurrence specifically, we assume that infinite loops without
5225 // side effects are undefined behavior, and then reason as follows:
5226 //
5227 // If the add recurrence is poison in any iteration, it is poison on all
5228 // future iterations (since incrementing poison yields poison). If the result
5229 // of the add recurrence is fed into the loop latch condition and the loop
5230 // does not contain any throws or exiting blocks other than the latch, we now
5231 // have the ability to "choose" whether the backedge is taken or not (by
5232 // choosing a sufficiently evil value for the poison feeding into the branch)
5233 // for every iteration including and after the one in which \p I first became
5234 // poison. There are two possibilities (let's call the iteration in which \p
5235 // I first became poison as K):
5236 //
5237 // 1. In the set of iterations including and after K, the loop body executes
5238 // no side effects. In this case executing the backege an infinte number
5239 // of times will yield undefined behavior.
5240 //
5241 // 2. In the set of iterations including and after K, the loop body executes
5242 // at least one side effect. In this case, that specific instance of side
5243 // effect is control dependent on poison, which also yields undefined
5244 // behavior.
5245
5246 auto *ExitingBB = L->getExitingBlock();
5247 auto *LatchBB = L->getLoopLatch();
5248 if (!ExitingBB || !LatchBB || ExitingBB != LatchBB)
5249 return false;
5250
5251 SmallPtrSet<const Instruction *, 16> Pushed;
5252 SmallVector<const Instruction *, 8> PoisonStack;
5253
5254 // We start by assuming \c I, the post-inc add recurrence, is poison. Only
5255 // things that are known to be fully poison under that assumption go on the
5256 // PoisonStack.
5257 Pushed.insert(I);
5258 PoisonStack.push_back(I);
5259
5260 bool LatchControlDependentOnPoison = false;
5261 while (!PoisonStack.empty() && !LatchControlDependentOnPoison) {
5262 const Instruction *Poison = PoisonStack.pop_back_val();
5263
5264 for (auto *PoisonUser : Poison->users()) {
5265 if (propagatesFullPoison(cast<Instruction>(PoisonUser))) {
5266 if (Pushed.insert(cast<Instruction>(PoisonUser)).second)
5267 PoisonStack.push_back(cast<Instruction>(PoisonUser));
5268 } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) {
5269 assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5269, __PRETTY_FUNCTION__))
;
5270 if (BI->getParent() == LatchBB) {
5271 LatchControlDependentOnPoison = true;
5272 break;
5273 }
5274 }
5275 }
5276 }
5277
5278 return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L);
5279}
5280
5281ScalarEvolution::LoopProperties
5282ScalarEvolution::getLoopProperties(const Loop *L) {
5283 typedef ScalarEvolution::LoopProperties LoopProperties;
5284
5285 auto Itr = LoopPropertiesCache.find(L);
5286 if (Itr == LoopPropertiesCache.end()) {
5287 auto HasSideEffects = [](Instruction *I) {
5288 if (auto *SI = dyn_cast<StoreInst>(I))
5289 return !SI->isSimple();
5290
5291 return I->mayHaveSideEffects();
5292 };
5293
5294 LoopProperties LP = {/* HasNoAbnormalExits */ true,
5295 /*HasNoSideEffects*/ true};
5296
5297 for (auto *BB : L->getBlocks())
5298 for (auto &I : *BB) {
5299 if (!isGuaranteedToTransferExecutionToSuccessor(&I))
5300 LP.HasNoAbnormalExits = false;
5301 if (HasSideEffects(&I))
5302 LP.HasNoSideEffects = false;
5303 if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects)
5304 break; // We're already as pessimistic as we can get.
5305 }
5306
5307 auto InsertPair = LoopPropertiesCache.insert({L, LP});
5308 assert(InsertPair.second && "We just checked!")((InsertPair.second && "We just checked!") ? static_cast
<void> (0) : __assert_fail ("InsertPair.second && \"We just checked!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5308, __PRETTY_FUNCTION__))
;
5309 Itr = InsertPair.first;
5310 }
5311
5312 return Itr->second;
5313}
5314
5315const SCEV *ScalarEvolution::createSCEV(Value *V) {
5316 if (!isSCEVable(V->getType()))
5317 return getUnknown(V);
5318
5319 if (Instruction *I = dyn_cast<Instruction>(V)) {
5320 // Don't attempt to analyze instructions in blocks that aren't
5321 // reachable. Such instructions don't matter, and they aren't required
5322 // to obey basic rules for definitions dominating uses which this
5323 // analysis depends on.
5324 if (!DT.isReachableFromEntry(I->getParent()))
5325 return getUnknown(V);
5326 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
5327 return getConstant(CI);
5328 else if (isa<ConstantPointerNull>(V))
5329 return getZero(V->getType());
5330 else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
5331 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
5332 else if (!isa<ConstantExpr>(V))
5333 return getUnknown(V);
5334
5335 Operator *U = cast<Operator>(V);
5336 if (auto BO = MatchBinaryOp(U, DT)) {
5337 switch (BO->Opcode) {
5338 case Instruction::Add: {
5339 // The simple thing to do would be to just call getSCEV on both operands
5340 // and call getAddExpr with the result. However if we're looking at a
5341 // bunch of things all added together, this can be quite inefficient,
5342 // because it leads to N-1 getAddExpr calls for N ultimate operands.
5343 // Instead, gather up all the operands and make a single getAddExpr call.
5344 // LLVM IR canonical form means we need only traverse the left operands.
5345 SmallVector<const SCEV *, 4> AddOps;
5346 do {
5347 if (BO->Op) {
5348 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
5349 AddOps.push_back(OpSCEV);
5350 break;
5351 }
5352
5353 // If a NUW or NSW flag can be applied to the SCEV for this
5354 // addition, then compute the SCEV for this addition by itself
5355 // with a separate call to getAddExpr. We need to do that
5356 // instead of pushing the operands of the addition onto AddOps,
5357 // since the flags are only known to apply to this particular
5358 // addition - they may not apply to other additions that can be
5359 // formed with operands from AddOps.
5360 const SCEV *RHS = getSCEV(BO->RHS);
5361 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
5362 if (Flags != SCEV::FlagAnyWrap) {
5363 const SCEV *LHS = getSCEV(BO->LHS);
5364 if (BO->Opcode == Instruction::Sub)
5365 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
5366 else
5367 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
5368 break;
5369 }
5370 }
5371
5372 if (BO->Opcode == Instruction::Sub)
5373 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
5374 else
5375 AddOps.push_back(getSCEV(BO->RHS));
5376
5377 auto NewBO = MatchBinaryOp(BO->LHS, DT);
5378 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
5379 NewBO->Opcode != Instruction::Sub)) {
5380 AddOps.push_back(getSCEV(BO->LHS));
5381 break;
5382 }
5383 BO = NewBO;
5384 } while (true);
5385
5386 return getAddExpr(AddOps);
5387 }
5388
5389 case Instruction::Mul: {
5390 SmallVector<const SCEV *, 4> MulOps;
5391 do {
5392 if (BO->Op) {
5393 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
5394 MulOps.push_back(OpSCEV);
5395 break;
5396 }
5397
5398 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
5399 if (Flags != SCEV::FlagAnyWrap) {
5400 MulOps.push_back(
5401 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
5402 break;
5403 }
5404 }
5405
5406 MulOps.push_back(getSCEV(BO->RHS));
5407 auto NewBO = MatchBinaryOp(BO->LHS, DT);
5408 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
5409 MulOps.push_back(getSCEV(BO->LHS));
5410 break;
5411 }
5412 BO = NewBO;
5413 } while (true);
5414
5415 return getMulExpr(MulOps);
5416 }
5417 case Instruction::UDiv:
5418 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
5419 case Instruction::Sub: {
5420 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5421 if (BO->Op)
5422 Flags = getNoWrapFlagsFromUB(BO->Op);
5423 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
5424 }
5425 case Instruction::And:
5426 // For an expression like x&255 that merely masks off the high bits,
5427 // use zext(trunc(x)) as the SCEV expression.
5428 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5429 if (CI->isNullValue())
5430 return getSCEV(BO->RHS);
5431 if (CI->isAllOnesValue())
5432 return getSCEV(BO->LHS);
5433 const APInt &A = CI->getValue();
5434
5435 // Instcombine's ShrinkDemandedConstant may strip bits out of
5436 // constants, obscuring what would otherwise be a low-bits mask.
5437 // Use computeKnownBits to compute what ShrinkDemandedConstant
5438 // knew about to reconstruct a low-bits mask value.
5439 unsigned LZ = A.countLeadingZeros();
5440 unsigned TZ = A.countTrailingZeros();
5441 unsigned BitWidth = A.getBitWidth();
5442 KnownBits Known(BitWidth);
5443 computeKnownBits(BO->LHS, Known, getDataLayout(),
5444 0, &AC, nullptr, &DT);
5445
5446 APInt EffectiveMask =
5447 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
5448 if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) {
5449 const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ));
5450 const SCEV *LHS = getSCEV(BO->LHS);
5451 const SCEV *ShiftedLHS = nullptr;
5452 if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) {
5453 if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) {
5454 // For an expression like (x * 8) & 8, simplify the multiply.
5455 unsigned MulZeros = OpC->getAPInt().countTrailingZeros();
5456 unsigned GCD = std::min(MulZeros, TZ);
5457 APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD);
5458 SmallVector<const SCEV*, 4> MulOps;
5459 MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD)));
5460 MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end());
5461 auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags());
5462 ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt));
5463 }
5464 }
5465 if (!ShiftedLHS)
5466 ShiftedLHS = getUDivExpr(LHS, MulCount);
5467 return getMulExpr(
5468 getZeroExtendExpr(
5469 getTruncateExpr(ShiftedLHS,
5470 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
5471 BO->LHS->getType()),
5472 MulCount);
5473 }
5474 }
5475 break;
5476
5477 case Instruction::Or:
5478 // If the RHS of the Or is a constant, we may have something like:
5479 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
5480 // optimizations will transparently handle this case.
5481 //
5482 // In order for this transformation to be safe, the LHS must be of the
5483 // form X*(2^n) and the Or constant must be less than 2^n.
5484 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5485 const SCEV *LHS = getSCEV(BO->LHS);
5486 const APInt &CIVal = CI->getValue();
5487 if (GetMinTrailingZeros(LHS) >=
5488 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
5489 // Build a plain add SCEV.
5490 const SCEV *S = getAddExpr(LHS, getSCEV(CI));
5491 // If the LHS of the add was an addrec and it has no-wrap flags,
5492 // transfer the no-wrap flags, since an or won't introduce a wrap.
5493 if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
5494 const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
5495 const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
5496 OldAR->getNoWrapFlags());
5497 }
5498 return S;
5499 }
5500 }
5501 break;
5502
5503 case Instruction::Xor:
5504 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5505 // If the RHS of xor is -1, then this is a not operation.
5506 if (CI->isAllOnesValue())
5507 return getNotSCEV(getSCEV(BO->LHS));
5508
5509 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
5510 // This is a variant of the check for xor with -1, and it handles
5511 // the case where instcombine has trimmed non-demanded bits out
5512 // of an xor with -1.
5513 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
5514 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
5515 if (LBO->getOpcode() == Instruction::And &&
5516 LCI->getValue() == CI->getValue())
5517 if (const SCEVZeroExtendExpr *Z =
5518 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
5519 Type *UTy = BO->LHS->getType();
5520 const SCEV *Z0 = Z->getOperand();
5521 Type *Z0Ty = Z0->getType();
5522 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
5523
5524 // If C is a low-bits mask, the zero extend is serving to
5525 // mask off the high bits. Complement the operand and
5526 // re-apply the zext.
5527 if (CI->getValue().isMask(Z0TySize))
5528 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
5529
5530 // If C is a single bit, it may be in the sign-bit position
5531 // before the zero-extend. In this case, represent the xor
5532 // using an add, which is equivalent, and re-apply the zext.
5533 APInt Trunc = CI->getValue().trunc(Z0TySize);
5534 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
5535 Trunc.isSignMask())
5536 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
5537 UTy);
5538 }
5539 }
5540 break;
5541
5542 case Instruction::Shl:
5543 // Turn shift left of a constant amount into a multiply.
5544 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
5545 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
5546
5547 // If the shift count is not less than the bitwidth, the result of
5548 // the shift is undefined. Don't try to analyze it, because the
5549 // resolution chosen here may differ from the resolution chosen in
5550 // other parts of the compiler.
5551 if (SA->getValue().uge(BitWidth))
5552 break;
5553
5554 // It is currently not resolved how to interpret NSW for left
5555 // shift by BitWidth - 1, so we avoid applying flags in that
5556 // case. Remove this check (or this comment) once the situation
5557 // is resolved. See
5558 // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html
5559 // and http://reviews.llvm.org/D8890 .
5560 auto Flags = SCEV::FlagAnyWrap;
5561 if (BO->Op && SA->getValue().ult(BitWidth - 1))
5562 Flags = getNoWrapFlagsFromUB(BO->Op);
5563
5564 Constant *X = ConstantInt::get(getContext(),
5565 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
5566 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
5567 }
5568 break;
5569
5570 case Instruction::AShr:
5571 // AShr X, C, where C is a constant.
5572 ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS);
5573 if (!CI)
5574 break;
5575
5576 Type *OuterTy = BO->LHS->getType();
5577 uint64_t BitWidth = getTypeSizeInBits(OuterTy);
5578 // If the shift count is not less than the bitwidth, the result of
5579 // the shift is undefined. Don't try to analyze it, because the
5580 // resolution chosen here may differ from the resolution chosen in
5581 // other parts of the compiler.
5582 if (CI->getValue().uge(BitWidth))
5583 break;
5584
5585 if (CI->isNullValue())
5586 return getSCEV(BO->LHS); // shift by zero --> noop
5587
5588 uint64_t AShrAmt = CI->getZExtValue();
5589 Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt);
5590
5591 Operator *L = dyn_cast<Operator>(BO->LHS);
5592 if (L && L->getOpcode() == Instruction::Shl) {
5593 // X = Shl A, n
5594 // Y = AShr X, m
5595 // Both n and m are constant.
5596
5597 const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0));
5598 if (L->getOperand(1) == BO->RHS)
5599 // For a two-shift sext-inreg, i.e. n = m,
5600 // use sext(trunc(x)) as the SCEV expression.
5601 return getSignExtendExpr(
5602 getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy);
5603
5604 ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1));
5605 if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) {
5606 uint64_t ShlAmt = ShlAmtCI->getZExtValue();
5607 if (ShlAmt > AShrAmt) {
5608 // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV
5609 // expression. We already checked that ShlAmt < BitWidth, so
5610 // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as
5611 // ShlAmt - AShrAmt < Amt.
5612 APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt,
5613 ShlAmt - AShrAmt);
5614 return getSignExtendExpr(
5615 getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy),
5616 getConstant(Mul)), OuterTy);
5617 }
5618 }
5619 }
5620 break;
5621 }
5622 }
5623
5624 switch (U->getOpcode()) {
5625 case Instruction::Trunc:
5626 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
5627
5628 case Instruction::ZExt:
5629 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
5630
5631 case Instruction::SExt:
5632 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
5633
5634 case Instruction::BitCast:
5635 // BitCasts are no-op casts so we just eliminate the cast.
5636 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
5637 return getSCEV(U->getOperand(0));
5638 break;
5639
5640 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
5641 // lead to pointer expressions which cannot safely be expanded to GEPs,
5642 // because ScalarEvolution doesn't respect the GEP aliasing rules when
5643 // simplifying integer expressions.
5644
5645 case Instruction::GetElementPtr:
5646 return createNodeForGEP(cast<GEPOperator>(U));
5647
5648 case Instruction::PHI:
5649 return createNodeForPHI(cast<PHINode>(U));
5650
5651 case Instruction::Select:
5652 // U can also be a select constant expr, which let fall through. Since
5653 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
5654 // constant expressions cannot have instructions as operands, we'd have
5655 // returned getUnknown for a select constant expressions anyway.
5656 if (isa<Instruction>(U))
5657 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
5658 U->getOperand(1), U->getOperand(2));
5659 break;
5660
5661 case Instruction::Call:
5662 case Instruction::Invoke:
5663 if (Value *RV = CallSite(U).getReturnedArgOperand())
5664 return getSCEV(RV);
5665 break;
5666 }
5667
5668 return getUnknown(V);
5669}
5670
5671
5672
5673//===----------------------------------------------------------------------===//
5674// Iteration Count Computation Code
5675//
5676
5677static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
5678 if (!ExitCount)
5679 return 0;
5680
5681 ConstantInt *ExitConst = ExitCount->getValue();
5682
5683 // Guard against huge trip counts.
5684 if (ExitConst->getValue().getActiveBits() > 32)
5685 return 0;
5686
5687 // In case of integer overflow, this returns 0, which is correct.
5688 return ((unsigned)ExitConst->getZExtValue()) + 1;
5689}
5690
5691unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) {
5692 if (BasicBlock *ExitingBB = L->getExitingBlock())
5693 return getSmallConstantTripCount(L, ExitingBB);
5694
5695 // No trip count information for multiple exits.
5696 return 0;
5697}
5698
5699unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L,
5700 BasicBlock *ExitingBlock) {
5701 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5701, __PRETTY_FUNCTION__))
;
5702 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5703, __PRETTY_FUNCTION__))
5703 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5703, __PRETTY_FUNCTION__))
;
5704 const SCEVConstant *ExitCount =
5705 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
5706 return getConstantTripCount(ExitCount);
5707}
5708
5709unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
5710 const auto *MaxExitCount =
5711 dyn_cast<SCEVConstant>(getMaxBackedgeTakenCount(L));
5712 return getConstantTripCount(MaxExitCount);
5713}
5714
5715unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) {
5716 if (BasicBlock *ExitingBB = L->getExitingBlock())
5717 return getSmallConstantTripMultiple(L, ExitingBB);
5718
5719 // No trip multiple information for multiple exits.
5720 return 0;
5721}
5722
5723/// Returns the largest constant divisor of the trip count of this loop as a
5724/// normal unsigned value, if possible. This means that the actual trip count is
5725/// always a multiple of the returned value (don't forget the trip count could
5726/// very well be zero as well!).
5727///
5728/// Returns 1 if the trip count is unknown or not guaranteed to be the
5729/// multiple of a constant (which is also the case if the trip count is simply
5730/// constant, use getSmallConstantTripCount for that case), Will also return 1
5731/// if the trip count is very large (>= 2^32).
5732///
5733/// As explained in the comments for getSmallConstantTripCount, this assumes
5734/// that control exits the loop via ExitingBlock.
5735unsigned
5736ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
5737 BasicBlock *ExitingBlock) {
5738 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5738, __PRETTY_FUNCTION__))
;
5739 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5740, __PRETTY_FUNCTION__))
5740 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5740, __PRETTY_FUNCTION__))
;
5741 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
5742 if (ExitCount == getCouldNotCompute())
5743 return 1;
5744
5745 // Get the trip count from the BE count by adding 1.
5746 const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType()));
5747
5748 const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr);
5749 if (!TC)
5750 // Attempt to factor more general cases. Returns the greatest power of
5751 // two divisor. If overflow happens, the trip count expression is still
5752 // divisible by the greatest power of 2 divisor returned.
5753 return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr));
5754
5755 ConstantInt *Result = TC->getValue();
5756
5757 // Guard against huge trip counts (this requires checking
5758 // for zero to handle the case where the trip count == -1 and the
5759 // addition wraps).
5760 if (!Result || Result->getValue().getActiveBits() > 32 ||
5761 Result->getValue().getActiveBits() == 0)
5762 return 1;
5763
5764 return (unsigned)Result->getZExtValue();
5765}
5766
5767/// Get the expression for the number of loop iterations for which this loop is
5768/// guaranteed not to exit via ExitingBlock. Otherwise return
5769/// SCEVCouldNotCompute.
5770const SCEV *ScalarEvolution::getExitCount(const Loop *L,
5771 BasicBlock *ExitingBlock) {
5772 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
5773}
5774
5775const SCEV *
5776ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
5777 SCEVUnionPredicate &Preds) {
5778 return getPredicatedBackedgeTakenInfo(L).getExact(this, &Preds);
5779}
5780
5781const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
5782 return getBackedgeTakenInfo(L).getExact(this);
5783}
5784
5785/// Similar to getBackedgeTakenCount, except return the least SCEV value that is
5786/// known never to be less than the actual backedge taken count.
5787const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
5788 return getBackedgeTakenInfo(L).getMax(this);
5789}
5790
5791bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) {
5792 return getBackedgeTakenInfo(L).isMaxOrZero(this);
5793}
5794
5795/// Push PHI nodes in the header of the given loop onto the given Worklist.
5796static void
5797PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
5798 BasicBlock *Header = L->getHeader();
5799
5800 // Push all Loop-header PHIs onto the Worklist stack.
5801 for (BasicBlock::iterator I = Header->begin();
5802 PHINode *PN = dyn_cast<PHINode>(I); ++I)
5803 Worklist.push_back(PN);
5804}
5805
5806const ScalarEvolution::BackedgeTakenInfo &
5807ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
5808 auto &BTI = getBackedgeTakenInfo(L);
5809 if (BTI.hasFullInfo())
5810 return BTI;
5811
5812 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
5813
5814 if (!Pair.second)
5815 return Pair.first->second;
5816
5817 BackedgeTakenInfo Result =
5818 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
5819
5820 return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result);
5821}
5822
5823const ScalarEvolution::BackedgeTakenInfo &
5824ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
5825 // Initially insert an invalid entry for this loop. If the insertion
5826 // succeeds, proceed to actually compute a backedge-taken count and
5827 // update the value. The temporary CouldNotCompute value tells SCEV
5828 // code elsewhere that it shouldn't attempt to request a new
5829 // backedge-taken count, which could result in infinite recursion.
5830 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
5831 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
5832 if (!Pair.second)
5833 return Pair.first->second;
5834
5835 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
5836 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
5837 // must be cleared in this scope.
5838 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
5839
5840 if (Result.getExact(this) != getCouldNotCompute()) {
5841 assert(isLoopInvariant(Result.getExact(this), L) &&((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant
(Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5843, __PRETTY_FUNCTION__))
5842 isLoopInvariant(Result.getMax(this), L) &&((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant
(Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5843, __PRETTY_FUNCTION__))
5843 "Computed backedge-taken count isn't loop invariant for loop!")((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant
(Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5843, __PRETTY_FUNCTION__))
;
5844 ++NumTripCountsComputed;
5845 }
5846 else if (Result.getMax(this) == getCouldNotCompute() &&
5847 isa<PHINode>(L->getHeader()->begin())) {
5848 // Only count loops that have phi nodes as not being computable.
5849 ++NumTripCountsNotComputed;
5850 }
5851
5852 // Now that we know more about the trip count for this loop, forget any
5853 // existing SCEV values for PHI nodes in this loop since they are only
5854 // conservative estimates made without the benefit of trip count
5855 // information. This is similar to the code in forgetLoop, except that
5856 // it handles SCEVUnknown PHI nodes specially.
5857 if (Result.hasAnyInfo()) {
5858 SmallVector<Instruction *, 16> Worklist;
5859 PushLoopPHIs(L, Worklist);
5860
5861 SmallPtrSet<Instruction *, 8> Visited;
5862 while (!Worklist.empty()) {
5863 Instruction *I = Worklist.pop_back_val();
5864 if (!Visited.insert(I).second)
5865 continue;
5866
5867 ValueExprMapType::iterator It =
5868 ValueExprMap.find_as(static_cast<Value *>(I));
5869 if (It != ValueExprMap.end()) {
5870 const SCEV *Old = It->second;
5871
5872 // SCEVUnknown for a PHI either means that it has an unrecognized
5873 // structure, or it's a PHI that's in the progress of being computed
5874 // by createNodeForPHI. In the former case, additional loop trip
5875 // count information isn't going to change anything. In the later
5876 // case, createNodeForPHI will perform the necessary updates on its
5877 // own when it gets to that point.
5878 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
5879 eraseValueFromMap(It->first);
5880 forgetMemoizedResults(Old);
5881 }
5882 if (PHINode *PN = dyn_cast<PHINode>(I))
5883 ConstantEvolutionLoopExitValue.erase(PN);
5884 }
5885
5886 PushDefUseChildren(I, Worklist);
5887 }
5888 }
5889
5890 // Re-lookup the insert position, since the call to
5891 // computeBackedgeTakenCount above could result in a
5892 // recusive call to getBackedgeTakenInfo (on a different
5893 // loop), which would invalidate the iterator computed
5894 // earlier.
5895 return BackedgeTakenCounts.find(L)->second = std::move(Result);
5896}
5897
5898void ScalarEvolution::forgetLoop(const Loop *L) {
5899 // Drop any stored trip count value.
5900 auto RemoveLoopFromBackedgeMap =
5901 [L](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
5902 auto BTCPos = Map.find(L);
5903 if (BTCPos != Map.end()) {
5904 BTCPos->second.clear();
5905 Map.erase(BTCPos);
5906 }
5907 };
5908
5909 RemoveLoopFromBackedgeMap(BackedgeTakenCounts);
5910 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts);
5911
5912 // Drop information about expressions based on loop-header PHIs.
5913 SmallVector<Instruction *, 16> Worklist;
5914 PushLoopPHIs(L, Worklist);
5915
5916 SmallPtrSet<Instruction *, 8> Visited;
5917 while (!Worklist.empty()) {
5918 Instruction *I = Worklist.pop_back_val();
5919 if (!Visited.insert(I).second)
5920 continue;
5921
5922 ValueExprMapType::iterator It =
5923 ValueExprMap.find_as(static_cast<Value *>(I));
5924 if (It != ValueExprMap.end()) {
5925 eraseValueFromMap(It->first);
5926 forgetMemoizedResults(It->second);
5927 if (PHINode *PN = dyn_cast<PHINode>(I))
5928 ConstantEvolutionLoopExitValue.erase(PN);
5929 }
5930
5931 PushDefUseChildren(I, Worklist);
5932 }
5933
5934 // Forget all contained loops too, to avoid dangling entries in the
5935 // ValuesAtScopes map.
5936 for (Loop *I : *L)
5937 forgetLoop(I);
5938
5939 LoopPropertiesCache.erase(L);
5940}
5941
5942void ScalarEvolution::forgetValue(Value *V) {
5943 Instruction *I = dyn_cast<Instruction>(V);
5944 if (!I) return;
5945
5946 // Drop information about expressions based on loop-header PHIs.
5947 SmallVector<Instruction *, 16> Worklist;
5948 Worklist.push_back(I);
5949
5950 SmallPtrSet<Instruction *, 8> Visited;
5951 while (!Worklist.empty()) {
5952 I = Worklist.pop_back_val();
5953 if (!Visited.insert(I).second)
5954 continue;
5955
5956 ValueExprMapType::iterator It =
5957 ValueExprMap.find_as(static_cast<Value *>(I));
5958 if (It != ValueExprMap.end()) {
5959 eraseValueFromMap(It->first);
5960 forgetMemoizedResults(It->second);
5961 if (PHINode *PN = dyn_cast<PHINode>(I))
5962 ConstantEvolutionLoopExitValue.erase(PN);
5963 }
5964
5965 PushDefUseChildren(I, Worklist);
5966 }
5967}
5968
5969/// Get the exact loop backedge taken count considering all loop exits. A
5970/// computable result can only be returned for loops with a single exit.
5971/// Returning the minimum taken count among all exits is incorrect because one
5972/// of the loop's exit limit's may have been skipped. howFarToZero assumes that
5973/// the limit of each loop test is never skipped. This is a valid assumption as
5974/// long as the loop exits via that test. For precise results, it is the
5975/// caller's responsibility to specify the relevant loop exit using
5976/// getExact(ExitingBlock, SE).
5977const SCEV *
5978ScalarEvolution::BackedgeTakenInfo::getExact(ScalarEvolution *SE,
5979 SCEVUnionPredicate *Preds) const {
5980 // If any exits were not computable, the loop is not computable.
5981 if (!isComplete() || ExitNotTaken.empty())
5982 return SE->getCouldNotCompute();
5983
5984 const SCEV *BECount = nullptr;
5985 for (auto &ENT : ExitNotTaken) {
5986 assert(ENT.ExactNotTaken != SE->getCouldNotCompute() && "bad exit SCEV")((ENT.ExactNotTaken != SE->getCouldNotCompute() &&
"bad exit SCEV") ? static_cast<void> (0) : __assert_fail
("ENT.ExactNotTaken != SE->getCouldNotCompute() && \"bad exit SCEV\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5986, __PRETTY_FUNCTION__))
;
5987
5988 if (!BECount)
5989 BECount = ENT.ExactNotTaken;
5990 else if (BECount != ENT.ExactNotTaken)
5991 return SE->getCouldNotCompute();
5992 if (Preds && !ENT.hasAlwaysTruePredicate())
5993 Preds->add(ENT.Predicate.get());
5994
5995 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5996, __PRETTY_FUNCTION__))
5996 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5996, __PRETTY_FUNCTION__))
;
5997 }
5998
5999 assert(BECount && "Invalid not taken count for loop exit")((BECount && "Invalid not taken count for loop exit")
? static_cast<void> (0) : __assert_fail ("BECount && \"Invalid not taken count for loop exit\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 5999, __PRETTY_FUNCTION__))
;
6000 return BECount;
6001}
6002
6003/// Get the exact not taken count for this loop exit.
6004const SCEV *
6005ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
6006 ScalarEvolution *SE) const {
6007 for (auto &ENT : ExitNotTaken)
6008 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6009 return ENT.ExactNotTaken;
6010
6011 return SE->getCouldNotCompute();
6012}
6013
6014/// getMax - Get the max backedge taken count for the loop.
6015const SCEV *
6016ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
6017 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6018 return !ENT.hasAlwaysTruePredicate();
6019 };
6020
6021 if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax())
6022 return SE->getCouldNotCompute();
6023
6024 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6025, __PRETTY_FUNCTION__))
6025 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6025, __PRETTY_FUNCTION__))
;
6026 return getMax();
6027}
6028
6029bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const {
6030 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6031 return !ENT.hasAlwaysTruePredicate();
6032 };
6033 return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
6034}
6035
6036bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
6037 ScalarEvolution *SE) const {
6038 if (getMax() && getMax() != SE->getCouldNotCompute() &&
6039 SE->hasOperand(getMax(), S))
6040 return true;
6041
6042 for (auto &ENT : ExitNotTaken)
6043 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
6044 SE->hasOperand(ENT.ExactNotTaken, S))
6045 return true;
6046
6047 return false;
6048}
6049
6050ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
6051 : ExactNotTaken(E), MaxNotTaken(E), MaxOrZero(false) {
6052 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6054, __PRETTY_FUNCTION__))
6053 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6054, __PRETTY_FUNCTION__))
6054 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6054, __PRETTY_FUNCTION__))
;
6055}
6056
6057ScalarEvolution::ExitLimit::ExitLimit(
6058 const SCEV *E, const SCEV *M, bool MaxOrZero,
6059 ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList)
6060 : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) {
6061 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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6063, __PRETTY_FUNCTION__))
6062 !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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6063, __PRETTY_FUNCTION__))
6063 "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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6063, __PRETTY_FUNCTION__))
;
6064 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6066, __PRETTY_FUNCTION__))
6065 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6066, __PRETTY_FUNCTION__))
6066 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6066, __PRETTY_FUNCTION__))
;
6067 for (auto *PredSet : PredSetList)
6068 for (auto *P : *PredSet)
6069 addPredicate(P);
6070}
6071
6072ScalarEvolution::ExitLimit::ExitLimit(
6073 const SCEV *E, const SCEV *M, bool MaxOrZero,
6074 const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
6075 : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
6076 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6078, __PRETTY_FUNCTION__))
6077 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6078, __PRETTY_FUNCTION__))
6078 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6078, __PRETTY_FUNCTION__))
;
6079}
6080
6081ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
6082 bool MaxOrZero)
6083 : ExitLimit(E, M, MaxOrZero, None) {
6084 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6086, __PRETTY_FUNCTION__))
6085 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6086, __PRETTY_FUNCTION__))
6086 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6086, __PRETTY_FUNCTION__))
;
6087}
6088
6089/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
6090/// computable exit into a persistent ExitNotTakenInfo array.
6091ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
6092 SmallVectorImpl<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo>
6093 &&ExitCounts,
6094 bool Complete, const SCEV *MaxCount, bool MaxOrZero)
6095 : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) {
6096 typedef ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo EdgeExitInfo;
6097 ExitNotTaken.reserve(ExitCounts.size());
6098 std::transform(
6099 ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken),
6100 [&](const EdgeExitInfo &EEI) {
6101 BasicBlock *ExitBB = EEI.first;
6102 const ExitLimit &EL = EEI.second;
6103 if (EL.Predicates.empty())
6104 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, nullptr);
6105
6106 std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate);
6107 for (auto *Pred : EL.Predicates)
6108 Predicate->add(Pred);
6109
6110 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, std::move(Predicate));
6111 });
6112 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6113, __PRETTY_FUNCTION__))
6113 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6113, __PRETTY_FUNCTION__))
;
6114}
6115
6116/// Invalidate this result and free the ExitNotTakenInfo array.
6117void ScalarEvolution::BackedgeTakenInfo::clear() {
6118 ExitNotTaken.clear();
6119}
6120
6121/// Compute the number of times the backedge of the specified loop will execute.
6122ScalarEvolution::BackedgeTakenInfo
6123ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
6124 bool AllowPredicates) {
6125 SmallVector<BasicBlock *, 8> ExitingBlocks;
6126 L->getExitingBlocks(ExitingBlocks);
6127
6128 typedef ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo EdgeExitInfo;
6129
6130 SmallVector<EdgeExitInfo, 4> ExitCounts;
6131 bool CouldComputeBECount = true;
6132 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
6133 const SCEV *MustExitMaxBECount = nullptr;
6134 const SCEV *MayExitMaxBECount = nullptr;
6135 bool MustExitMaxOrZero = false;
6136
6137 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
6138 // and compute maxBECount.
6139 // Do a union of all the predicates here.
6140 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
6141 BasicBlock *ExitBB = ExitingBlocks[i];
6142 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
6143
6144 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6145, __PRETTY_FUNCTION__))
6145 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6145, __PRETTY_FUNCTION__))
;
6146
6147 // 1. For each exit that can be computed, add an entry to ExitCounts.
6148 // CouldComputeBECount is true only if all exits can be computed.
6149 if (EL.ExactNotTaken == getCouldNotCompute())
6150 // We couldn't compute an exact value for this exit, so
6151 // we won't be able to compute an exact value for the loop.
6152 CouldComputeBECount = false;
6153 else
6154 ExitCounts.emplace_back(ExitBB, EL);
6155
6156 // 2. Derive the loop's MaxBECount from each exit's max number of
6157 // non-exiting iterations. Partition the loop exits into two kinds:
6158 // LoopMustExits and LoopMayExits.
6159 //
6160 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
6161 // is a LoopMayExit. If any computable LoopMustExit is found, then
6162 // MaxBECount is the minimum EL.MaxNotTaken of computable
6163 // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum
6164 // EL.MaxNotTaken, where CouldNotCompute is considered greater than any
6165 // computable EL.MaxNotTaken.
6166 if (EL.MaxNotTaken != getCouldNotCompute() && Latch &&
6167 DT.dominates(ExitBB, Latch)) {
6168 if (!MustExitMaxBECount) {
6169 MustExitMaxBECount = EL.MaxNotTaken;
6170 MustExitMaxOrZero = EL.MaxOrZero;
6171 } else {
6172 MustExitMaxBECount =
6173 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken);
6174 }
6175 } else if (MayExitMaxBECount != getCouldNotCompute()) {
6176 if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute())
6177 MayExitMaxBECount = EL.MaxNotTaken;
6178 else {
6179 MayExitMaxBECount =
6180 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken);
6181 }
6182 }
6183 }
6184 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
6185 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
6186 // The loop backedge will be taken the maximum or zero times if there's
6187 // a single exit that must be taken the maximum or zero times.
6188 bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1);
6189 return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount,
6190 MaxBECount, MaxOrZero);
6191}
6192
6193ScalarEvolution::ExitLimit
6194ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
6195 bool AllowPredicates) {
6196
6197 // Okay, we've chosen an exiting block. See what condition causes us to exit
6198 // at this block and remember the exit block and whether all other targets
6199 // lead to the loop header.
6200 bool MustExecuteLoopHeader = true;
6201 BasicBlock *Exit = nullptr;
6202 for (auto *SBB : successors(ExitingBlock))
6203 if (!L->contains(SBB)) {
6204 if (Exit) // Multiple exit successors.
6205 return getCouldNotCompute();
6206 Exit = SBB;
6207 } else if (SBB != L->getHeader()) {
6208 MustExecuteLoopHeader = false;
6209 }
6210
6211 // At this point, we know we have a conditional branch that determines whether
6212 // the loop is exited. However, we don't know if the branch is executed each
6213 // time through the loop. If not, then the execution count of the branch will
6214 // not be equal to the trip count of the loop.
6215 //
6216 // Currently we check for this by checking to see if the Exit branch goes to
6217 // the loop header. If so, we know it will always execute the same number of
6218 // times as the loop. We also handle the case where the exit block *is* the
6219 // loop header. This is common for un-rotated loops.
6220 //
6221 // If both of those tests fail, walk up the unique predecessor chain to the
6222 // header, stopping if there is an edge that doesn't exit the loop. If the
6223 // header is reached, the execution count of the branch will be equal to the
6224 // trip count of the loop.
6225 //
6226 // More extensive analysis could be done to handle more cases here.
6227 //
6228 if (!MustExecuteLoopHeader && ExitingBlock != L->getHeader()) {
6229 // The simple checks failed, try climbing the unique predecessor chain
6230 // up to the header.
6231 bool Ok = false;
6232 for (BasicBlock *BB = ExitingBlock; BB; ) {
6233 BasicBlock *Pred = BB->getUniquePredecessor();
6234 if (!Pred)
6235 return getCouldNotCompute();
6236 TerminatorInst *PredTerm = Pred->getTerminator();
6237 for (const BasicBlock *PredSucc : PredTerm->successors()) {
6238 if (PredSucc == BB)
6239 continue;
6240 // If the predecessor has a successor that isn't BB and isn't
6241 // outside the loop, assume the worst.
6242 if (L->contains(PredSucc))
6243 return getCouldNotCompute();
6244 }
6245 if (Pred == L->getHeader()) {
6246 Ok = true;
6247 break;
6248 }
6249 BB = Pred;
6250 }
6251 if (!Ok)
6252 return getCouldNotCompute();
6253 }
6254
6255 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
6256 TerminatorInst *Term = ExitingBlock->getTerminator();
6257 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
6258 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6258, __PRETTY_FUNCTION__))
;
6259 // Proceed to the next level to examine the exit condition expression.
6260 return computeExitLimitFromCond(
6261 L, BI->getCondition(), BI->getSuccessor(0), BI->getSuccessor(1),
6262 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
6263 }
6264
6265 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term))
6266 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
6267 /*ControlsExit=*/IsOnlyExit);
6268
6269 return getCouldNotCompute();
6270}
6271
6272ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond(
6273 const Loop *L, Value *ExitCond, BasicBlock *TBB, BasicBlock *FBB,
6274 bool ControlsExit, bool AllowPredicates) {
6275 ScalarEvolution::ExitLimitCacheTy Cache(L, TBB, FBB, AllowPredicates);
6276 return computeExitLimitFromCondCached(Cache, L, ExitCond, TBB, FBB,
6277 ControlsExit, AllowPredicates);
6278}
6279
6280Optional<ScalarEvolution::ExitLimit>
6281ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond,
6282 BasicBlock *TBB, BasicBlock *FBB,
6283 bool ControlsExit, bool AllowPredicates) {
6284 (void)this->L;
6285 (void)this->TBB;
6286 (void)this->FBB;
6287 (void)this->AllowPredicates;
6288
6289 assert(this->L == L && this->TBB == TBB && this->FBB == FBB &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6291, __PRETTY_FUNCTION__))
6290 this->AllowPredicates == AllowPredicates &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6291, __PRETTY_FUNCTION__))
6291 "Variance in assumed invariant key components!")((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6291, __PRETTY_FUNCTION__))
;
6292 auto Itr = TripCountMap.find({ExitCond, ControlsExit});
6293 if (Itr == TripCountMap.end())
6294 return None;
6295 return Itr->second;
6296}
6297
6298void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond,
6299 BasicBlock *TBB, BasicBlock *FBB,
6300 bool ControlsExit,
6301 bool AllowPredicates,
6302 const ExitLimit &EL) {
6303 assert(this->L == L && this->TBB == TBB && this->FBB == FBB &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6305, __PRETTY_FUNCTION__))
6304 this->AllowPredicates == AllowPredicates &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6305, __PRETTY_FUNCTION__))
6305 "Variance in assumed invariant key components!")((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6305, __PRETTY_FUNCTION__))
;
6306
6307 auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL});
6308 assert(InsertResult.second && "Expected successful insertion!")((InsertResult.second && "Expected successful insertion!"
) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expected successful insertion!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6308, __PRETTY_FUNCTION__))
;
6309 (void)InsertResult;
6310}
6311
6312ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached(
6313 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, BasicBlock *TBB,
6314 BasicBlock *FBB, bool ControlsExit, bool AllowPredicates) {
6315
6316 if (auto MaybeEL =
6317 Cache.find(L, ExitCond, TBB, FBB, ControlsExit, AllowPredicates))
6318 return *MaybeEL;
6319
6320 ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, TBB, FBB,
6321 ControlsExit, AllowPredicates);
6322 Cache.insert(L, ExitCond, TBB, FBB, ControlsExit, AllowPredicates, EL);
6323 return EL;
6324}
6325
6326ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
6327 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, BasicBlock *TBB,
6328 BasicBlock *FBB, bool ControlsExit, bool AllowPredicates) {
6329 // Check if the controlling expression for this loop is an And or Or.
6330 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
6331 if (BO->getOpcode() == Instruction::And) {
6332 // Recurse on the operands of the and.
6333 bool EitherMayExit = L->contains(TBB);
6334 ExitLimit EL0 = computeExitLimitFromCondCached(
6335 Cache, L, BO->getOperand(0), TBB, FBB, ControlsExit && !EitherMayExit,
6336 AllowPredicates);
6337 ExitLimit EL1 = computeExitLimitFromCondCached(
6338 Cache, L, BO->getOperand(1), TBB, FBB, ControlsExit && !EitherMayExit,
6339 AllowPredicates);
6340 const SCEV *BECount = getCouldNotCompute();
6341 const SCEV *MaxBECount = getCouldNotCompute();
6342 if (EitherMayExit) {
6343 // Both conditions must be true for the loop to continue executing.
6344 // Choose the less conservative count.
6345 if (EL0.ExactNotTaken == getCouldNotCompute() ||
6346 EL1.ExactNotTaken == getCouldNotCompute())
6347 BECount = getCouldNotCompute();
6348 else
6349 BECount =
6350 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
6351 if (EL0.MaxNotTaken == getCouldNotCompute())
6352 MaxBECount = EL1.MaxNotTaken;
6353 else if (EL1.MaxNotTaken == getCouldNotCompute())
6354 MaxBECount = EL0.MaxNotTaken;
6355 else
6356 MaxBECount =
6357 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
6358 } else {
6359 // Both conditions must be true at the same time for the loop to exit.
6360 // For now, be conservative.
6361 assert(L->contains(FBB) && "Loop block has no successor in loop!")((L->contains(FBB) && "Loop block has no successor in loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(FBB) && \"Loop block has no successor in loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6361, __PRETTY_FUNCTION__))
;
6362 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
6363 MaxBECount = EL0.MaxNotTaken;
6364 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
6365 BECount = EL0.ExactNotTaken;
6366 }
6367
6368 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
6369 // to be more aggressive when computing BECount than when computing
6370 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
6371 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
6372 // to not.
6373 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
6374 !isa<SCEVCouldNotCompute>(BECount))
6375 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
6376
6377 return ExitLimit(BECount, MaxBECount, false,
6378 {&EL0.Predicates, &EL1.Predicates});
6379 }
6380 if (BO->getOpcode() == Instruction::Or) {
6381 // Recurse on the operands of the or.
6382 bool EitherMayExit = L->contains(FBB);
6383 ExitLimit EL0 = computeExitLimitFromCondCached(
6384 Cache, L, BO->getOperand(0), TBB, FBB, ControlsExit && !EitherMayExit,
6385 AllowPredicates);
6386 ExitLimit EL1 = computeExitLimitFromCondCached(
6387 Cache, L, BO->getOperand(1), TBB, FBB, ControlsExit && !EitherMayExit,
6388 AllowPredicates);
6389 const SCEV *BECount = getCouldNotCompute();
6390 const SCEV *MaxBECount = getCouldNotCompute();
6391 if (EitherMayExit) {
6392 // Both conditions must be false for the loop to continue executing.
6393 // Choose the less conservative count.
6394 if (EL0.ExactNotTaken == getCouldNotCompute() ||
6395 EL1.ExactNotTaken == getCouldNotCompute())
6396 BECount = getCouldNotCompute();
6397 else
6398 BECount =
6399 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
6400 if (EL0.MaxNotTaken == getCouldNotCompute())
6401 MaxBECount = EL1.MaxNotTaken;
6402 else if (EL1.MaxNotTaken == getCouldNotCompute())
6403 MaxBECount = EL0.MaxNotTaken;
6404 else
6405 MaxBECount =
6406 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
6407 } else {
6408 // Both conditions must be false at the same time for the loop to exit.
6409 // For now, be conservative.
6410 assert(L->contains(TBB) && "Loop block has no successor in loop!")((L->contains(TBB) && "Loop block has no successor in loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(TBB) && \"Loop block has no successor in loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6410, __PRETTY_FUNCTION__))
;
6411 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
6412 MaxBECount = EL0.MaxNotTaken;
6413 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
6414 BECount = EL0.ExactNotTaken;
6415 }
6416
6417 return ExitLimit(BECount, MaxBECount, false,
6418 {&EL0.Predicates, &EL1.Predicates});
6419 }
6420 }
6421
6422 // With an icmp, it may be feasible to compute an exact backedge-taken count.
6423 // Proceed to the next level to examine the icmp.
6424 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
6425 ExitLimit EL =
6426 computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit);
6427 if (EL.hasFullInfo() || !AllowPredicates)
6428 return EL;
6429
6430 // Try again, but use SCEV predicates this time.
6431 return computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit,
6432 /*AllowPredicates=*/true);
6433 }
6434
6435 // Check for a constant condition. These are normally stripped out by
6436 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
6437 // preserve the CFG and is temporarily leaving constant conditions
6438 // in place.
6439 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
6440 if (L->contains(FBB) == !CI->getZExtValue())
6441 // The backedge is always taken.
6442 return getCouldNotCompute();
6443 else
6444 // The backedge is never taken.
6445 return getZero(CI->getType());
6446 }
6447
6448 // If it's not an integer or pointer comparison then compute it the hard way.
6449 return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
6450}
6451
6452ScalarEvolution::ExitLimit
6453ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
6454 ICmpInst *ExitCond,
6455 BasicBlock *TBB,
6456 BasicBlock *FBB,
6457 bool ControlsExit,
6458 bool AllowPredicates) {
6459
6460 // If the condition was exit on true, convert the condition to exit on false
6461 ICmpInst::Predicate Cond;
6462 if (!L->contains(FBB))
6463 Cond = ExitCond->getPredicate();
6464 else
6465 Cond = ExitCond->getInversePredicate();
6466
6467 // Handle common loops like: for (X = "string"; *X; ++X)
6468 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
6469 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
6470 ExitLimit ItCnt =
6471 computeLoadConstantCompareExitLimit(LI, RHS, L, Cond);
6472 if (ItCnt.hasAnyInfo())
6473 return ItCnt;
6474 }
6475
6476 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
6477 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
6478
6479 // Try to evaluate any dependencies out of the loop.
6480 LHS = getSCEVAtScope(LHS, L);
6481 RHS = getSCEVAtScope(RHS, L);
6482
6483 // At this point, we would like to compute how many iterations of the
6484 // loop the predicate will return true for these inputs.
6485 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
6486 // If there is a loop-invariant, force it into the RHS.
6487 std::swap(LHS, RHS);
6488 Cond = ICmpInst::getSwappedPredicate(Cond);
6489 }
6490
6491 // Simplify the operands before analyzing them.
6492 (void)SimplifyICmpOperands(Cond, LHS, RHS);
6493
6494 // If we have a comparison of a chrec against a constant, try to use value
6495 // ranges to answer this query.
6496 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
6497 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
6498 if (AddRec->getLoop() == L) {
6499 // Form the constant range.
6500 ConstantRange CompRange =
6501 ConstantRange::makeExactICmpRegion(Cond, RHSC->getAPInt());
6502
6503 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
6504 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
6505 }
6506
6507 switch (Cond) {
6508 case ICmpInst::ICMP_NE: { // while (X != Y)
6509 // Convert to: while (X-Y != 0)
6510 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
6511 AllowPredicates);
6512 if (EL.hasAnyInfo()) return EL;
6513 break;
6514 }
6515 case ICmpInst::ICMP_EQ: { // while (X == Y)
6516 // Convert to: while (X-Y == 0)
6517 ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L);
6518 if (EL.hasAnyInfo()) return EL;
6519 break;
6520 }
6521 case ICmpInst::ICMP_SLT:
6522 case ICmpInst::ICMP_ULT: { // while (X < Y)
6523 bool IsSigned = Cond == ICmpInst::ICMP_SLT;
6524 ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
6525 AllowPredicates);
6526 if (EL.hasAnyInfo()) return EL;
6527 break;
6528 }
6529 case ICmpInst::ICMP_SGT:
6530 case ICmpInst::ICMP_UGT: { // while (X > Y)
6531 bool IsSigned = Cond == ICmpInst::ICMP_SGT;
6532 ExitLimit EL =
6533 howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
6534 AllowPredicates);
6535 if (EL.hasAnyInfo()) return EL;
6536 break;
6537 }
6538 default:
6539 break;
6540 }
6541
6542 auto *ExhaustiveCount =
6543 computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
6544
6545 if (!isa<SCEVCouldNotCompute>(ExhaustiveCount))
6546 return ExhaustiveCount;
6547
6548 return computeShiftCompareExitLimit(ExitCond->getOperand(0),
6549 ExitCond->getOperand(1), L, Cond);
6550}
6551
6552ScalarEvolution::ExitLimit
6553ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
6554 SwitchInst *Switch,
6555 BasicBlock *ExitingBlock,
6556 bool ControlsExit) {
6557 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6557, __PRETTY_FUNCTION__))
;
6558
6559 // Give up if the exit is the default dest of a switch.
6560 if (Switch->getDefaultDest() == ExitingBlock)
6561 return getCouldNotCompute();
6562
6563 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6564, __PRETTY_FUNCTION__))
6564 "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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6564, __PRETTY_FUNCTION__))
;
6565 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
6566 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
6567
6568 // while (X != Y) --> while (X-Y != 0)
6569 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
6570 if (EL.hasAnyInfo())
6571 return EL;
6572
6573 return getCouldNotCompute();
6574}
6575
6576static ConstantInt *
6577EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
6578 ScalarEvolution &SE) {
6579 const SCEV *InVal = SE.getConstant(C);
6580 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
6581 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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6582, __PRETTY_FUNCTION__))
6582 "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?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6582, __PRETTY_FUNCTION__))
;
6583 return cast<SCEVConstant>(Val)->getValue();
6584}
6585
6586/// Given an exit condition of 'icmp op load X, cst', try to see if we can
6587/// compute the backedge execution count.
6588ScalarEvolution::ExitLimit
6589ScalarEvolution::computeLoadConstantCompareExitLimit(
6590 LoadInst *LI,
6591 Constant *RHS,
6592 const Loop *L,
6593 ICmpInst::Predicate predicate) {
6594
6595 if (LI->isVolatile()) return getCouldNotCompute();
6596
6597 // Check to see if the loaded pointer is a getelementptr of a global.
6598 // TODO: Use SCEV instead of manually grubbing with GEPs.
6599 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
6600 if (!GEP) return getCouldNotCompute();
6601
6602 // Make sure that it is really a constant global we are gepping, with an
6603 // initializer, and make sure the first IDX is really 0.
6604 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
6605 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
6606 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
6607 !cast<Constant>(GEP->getOperand(1))->isNullValue())
6608 return getCouldNotCompute();
6609
6610 // Okay, we allow one non-constant index into the GEP instruction.
6611 Value *VarIdx = nullptr;
6612 std::vector<Constant*> Indexes;
6613 unsigned VarIdxNum = 0;
6614 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
6615 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
6616 Indexes.push_back(CI);
6617 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
6618 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
6619 VarIdx = GEP->getOperand(i);
6620 VarIdxNum = i-2;
6621 Indexes.push_back(nullptr);
6622 }
6623
6624 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
6625 if (!VarIdx)
6626 return getCouldNotCompute();
6627
6628 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
6629 // Check to see if X is a loop variant variable value now.
6630 const SCEV *Idx = getSCEV(VarIdx);
6631 Idx = getSCEVAtScope(Idx, L);
6632
6633 // We can only recognize very limited forms of loop index expressions, in
6634 // particular, only affine AddRec's like {C1,+,C2}.
6635 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
6636 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
6637 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
6638 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
6639 return getCouldNotCompute();
6640
6641 unsigned MaxSteps = MaxBruteForceIterations;
6642 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
6643 ConstantInt *ItCst = ConstantInt::get(
6644 cast<IntegerType>(IdxExpr->getType()), IterationNum);
6645 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
6646
6647 // Form the GEP offset.
6648 Indexes[VarIdxNum] = Val;
6649
6650 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
6651 Indexes);
6652 if (!Result) break; // Cannot compute!
6653
6654 // Evaluate the condition for this iteration.
6655 Result = ConstantExpr::getICmp(predicate, Result, RHS);
6656 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
6657 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
6658 ++NumArrayLenItCounts;
6659 return getConstant(ItCst); // Found terminating iteration!
6660 }
6661 }
6662 return getCouldNotCompute();
6663}
6664
6665ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
6666 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
6667 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
6668 if (!RHS)
6669 return getCouldNotCompute();
6670
6671 const BasicBlock *Latch = L->getLoopLatch();
6672 if (!Latch)
6673 return getCouldNotCompute();
6674
6675 const BasicBlock *Predecessor = L->getLoopPredecessor();
6676 if (!Predecessor)
6677 return getCouldNotCompute();
6678
6679 // Return true if V is of the form "LHS `shift_op` <positive constant>".
6680 // Return LHS in OutLHS and shift_opt in OutOpCode.
6681 auto MatchPositiveShift =
6682 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
6683
6684 using namespace PatternMatch;
6685
6686 ConstantInt *ShiftAmt;
6687 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6688 OutOpCode = Instruction::LShr;
6689 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6690 OutOpCode = Instruction::AShr;
6691 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6692 OutOpCode = Instruction::Shl;
6693 else
6694 return false;
6695
6696 return ShiftAmt->getValue().isStrictlyPositive();
6697 };
6698
6699 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
6700 //
6701 // loop:
6702 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
6703 // %iv.shifted = lshr i32 %iv, <positive constant>
6704 //
6705 // Return true on a successful match. Return the corresponding PHI node (%iv
6706 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
6707 auto MatchShiftRecurrence =
6708 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
6709 Optional<Instruction::BinaryOps> PostShiftOpCode;
6710
6711 {
6712 Instruction::BinaryOps OpC;
6713 Value *V;
6714
6715 // If we encounter a shift instruction, "peel off" the shift operation,
6716 // and remember that we did so. Later when we inspect %iv's backedge
6717 // value, we will make sure that the backedge value uses the same
6718 // operation.
6719 //
6720 // Note: the peeled shift operation does not have to be the same
6721 // instruction as the one feeding into the PHI's backedge value. We only
6722 // really care about it being the same *kind* of shift instruction --
6723 // that's all that is required for our later inferences to hold.
6724 if (MatchPositiveShift(LHS, V, OpC)) {
6725 PostShiftOpCode = OpC;
6726 LHS = V;
6727 }
6728 }
6729
6730 PNOut = dyn_cast<PHINode>(LHS);
6731 if (!PNOut || PNOut->getParent() != L->getHeader())
6732 return false;
6733
6734 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
6735 Value *OpLHS;
6736
6737 return
6738 // The backedge value for the PHI node must be a shift by a positive
6739 // amount
6740 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
6741
6742 // of the PHI node itself
6743 OpLHS == PNOut &&
6744
6745 // and the kind of shift should be match the kind of shift we peeled
6746 // off, if any.
6747 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
6748 };
6749
6750 PHINode *PN;
6751 Instruction::BinaryOps OpCode;
6752 if (!MatchShiftRecurrence(LHS, PN, OpCode))
6753 return getCouldNotCompute();
6754
6755 const DataLayout &DL = getDataLayout();
6756
6757 // The key rationale for this optimization is that for some kinds of shift
6758 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
6759 // within a finite number of iterations. If the condition guarding the
6760 // backedge (in the sense that the backedge is taken if the condition is true)
6761 // is false for the value the shift recurrence stabilizes to, then we know
6762 // that the backedge is taken only a finite number of times.
6763
6764 ConstantInt *StableValue = nullptr;
6765 switch (OpCode) {
6766 default:
6767 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6767)
;
6768
6769 case Instruction::AShr: {
6770 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
6771 // bitwidth(K) iterations.
6772 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
6773 KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr,
6774 Predecessor->getTerminator(), &DT);
6775 auto *Ty = cast<IntegerType>(RHS->getType());
6776 if (Known.isNonNegative())
6777 StableValue = ConstantInt::get(Ty, 0);
6778 else if (Known.isNegative())
6779 StableValue = ConstantInt::get(Ty, -1, true);
6780 else
6781 return getCouldNotCompute();
6782
6783 break;
6784 }
6785 case Instruction::LShr:
6786 case Instruction::Shl:
6787 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
6788 // stabilize to 0 in at most bitwidth(K) iterations.
6789 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
6790 break;
6791 }
6792
6793 auto *Result =
6794 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
6795 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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6796, __PRETTY_FUNCTION__))
6796 "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\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6796, __PRETTY_FUNCTION__))
;
6797
6798 if (Result->isZeroValue()) {
6799 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
6800 const SCEV *UpperBound =
6801 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
6802 return ExitLimit(getCouldNotCompute(), UpperBound, false);
6803 }
6804
6805 return getCouldNotCompute();
6806}
6807
6808/// Return true if we can constant fold an instruction of the specified type,
6809/// assuming that all operands were constants.
6810static bool CanConstantFold(const Instruction *I) {
6811 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
6812 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
6813 isa<LoadInst>(I))
6814 return true;
6815
6816 if (const CallInst *CI = dyn_cast<CallInst>(I))
6817 if (const Function *F = CI->getCalledFunction())
6818 return canConstantFoldCallTo(CI, F);
6819 return false;
6820}
6821
6822/// Determine whether this instruction can constant evolve within this loop
6823/// assuming its operands can all constant evolve.
6824static bool canConstantEvolve(Instruction *I, const Loop *L) {
6825 // An instruction outside of the loop can't be derived from a loop PHI.
6826 if (!L->contains(I)) return false;
6827
6828 if (isa<PHINode>(I)) {
6829 // We don't currently keep track of the control flow needed to evaluate
6830 // PHIs, so we cannot handle PHIs inside of loops.
6831 return L->getHeader() == I->getParent();
6832 }
6833
6834 // If we won't be able to constant fold this expression even if the operands
6835 // are constants, bail early.
6836 return CanConstantFold(I);
6837}
6838
6839/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
6840/// recursing through each instruction operand until reaching a loop header phi.
6841static PHINode *
6842getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
6843 DenseMap<Instruction *, PHINode *> &PHIMap,
6844 unsigned Depth) {
6845 if (Depth > MaxConstantEvolvingDepth)
6846 return nullptr;
6847
6848 // Otherwise, we can evaluate this instruction if all of its operands are
6849 // constant or derived from a PHI node themselves.
6850 PHINode *PHI = nullptr;
6851 for (Value *Op : UseInst->operands()) {
6852 if (isa<Constant>(Op)) continue;
6853
6854 Instruction *OpInst = dyn_cast<Instruction>(Op);
6855 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
6856
6857 PHINode *P = dyn_cast<PHINode>(OpInst);
6858 if (!P)
6859 // If this operand is already visited, reuse the prior result.
6860 // We may have P != PHI if this is the deepest point at which the
6861 // inconsistent paths meet.
6862 P = PHIMap.lookup(OpInst);
6863 if (!P) {
6864 // Recurse and memoize the results, whether a phi is found or not.
6865 // This recursive call invalidates pointers into PHIMap.
6866 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap, Depth + 1);
6867 PHIMap[OpInst] = P;
6868 }
6869 if (!P)
6870 return nullptr; // Not evolving from PHI
6871 if (PHI && PHI != P)
6872 return nullptr; // Evolving from multiple different PHIs.
6873 PHI = P;
6874 }
6875 // This is a expression evolving from a constant PHI!
6876 return PHI;
6877}
6878
6879/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
6880/// in the loop that V is derived from. We allow arbitrary operations along the
6881/// way, but the operands of an operation must either be constants or a value
6882/// derived from a constant PHI. If this expression does not fit with these
6883/// constraints, return null.
6884static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
6885 Instruction *I = dyn_cast<Instruction>(V);
6886 if (!I || !canConstantEvolve(I, L)) return nullptr;
6887
6888 if (PHINode *PN = dyn_cast<PHINode>(I))
6889 return PN;
6890
6891 // Record non-constant instructions contained by the loop.
6892 DenseMap<Instruction *, PHINode *> PHIMap;
6893 return getConstantEvolvingPHIOperands(I, L, PHIMap, 0);
6894}
6895
6896/// EvaluateExpression - Given an expression that passes the
6897/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
6898/// in the loop has the value PHIVal. If we can't fold this expression for some
6899/// reason, return null.
6900static Constant *EvaluateExpression(Value *V, const Loop *L,
6901 DenseMap<Instruction *, Constant *> &Vals,
6902 const DataLayout &DL,
6903 const TargetLibraryInfo *TLI) {
6904 // Convenient constant check, but redundant for recursive calls.
6905 if (Constant *C = dyn_cast<Constant>(V)) return C;
6906 Instruction *I = dyn_cast<Instruction>(V);
6907 if (!I) return nullptr;
6908
6909 if (Constant *C = Vals.lookup(I)) return C;
6910
6911 // An instruction inside the loop depends on a value outside the loop that we
6912 // weren't given a mapping for, or a value such as a call inside the loop.
6913 if (!canConstantEvolve(I, L)) return nullptr;
6914
6915 // An unmapped PHI can be due to a branch or another loop inside this loop,
6916 // or due to this not being the initial iteration through a loop where we
6917 // couldn't compute the evolution of this particular PHI last time.
6918 if (isa<PHINode>(I)) return nullptr;
6919
6920 std::vector<Constant*> Operands(I->getNumOperands());
6921
6922 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
6923 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
6924 if (!Operand) {
6925 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
6926 if (!Operands[i]) return nullptr;
6927 continue;
6928 }
6929 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
6930 Vals[Operand] = C;
6931 if (!C) return nullptr;
6932 Operands[i] = C;
6933 }
6934
6935 if (CmpInst *CI = dyn_cast<CmpInst>(I))
6936 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
6937 Operands[1], DL, TLI);
6938 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6939 if (!LI->isVolatile())
6940 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
6941 }
6942 return ConstantFoldInstOperands(I, Operands, DL, TLI);
6943}
6944
6945
6946// If every incoming value to PN except the one for BB is a specific Constant,
6947// return that, else return nullptr.
6948static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
6949 Constant *IncomingVal = nullptr;
6950
6951 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
6952 if (PN->getIncomingBlock(i) == BB)
6953 continue;
6954
6955 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
6956 if (!CurrentVal)
6957 return nullptr;
6958
6959 if (IncomingVal != CurrentVal) {
6960 if (IncomingVal)
6961 return nullptr;
6962 IncomingVal = CurrentVal;
6963 }
6964 }
6965
6966 return IncomingVal;
6967}
6968
6969/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
6970/// in the header of its containing loop, we know the loop executes a
6971/// constant number of times, and the PHI node is just a recurrence
6972/// involving constants, fold it.
6973Constant *
6974ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
6975 const APInt &BEs,
6976 const Loop *L) {
6977 auto I = ConstantEvolutionLoopExitValue.find(PN);
6978 if (I != ConstantEvolutionLoopExitValue.end())
6979 return I->second;
6980
6981 if (BEs.ugt(MaxBruteForceIterations))
6982 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
6983
6984 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
6985
6986 DenseMap<Instruction *, Constant *> CurrentIterVals;
6987 BasicBlock *Header = L->getHeader();
6988 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 6988, __PRETTY_FUNCTION__))
;
6989
6990 BasicBlock *Latch = L->getLoopLatch();
6991 if (!Latch)
6992 return nullptr;
6993
6994 for (auto &I : *Header) {
6995 PHINode *PHI = dyn_cast<PHINode>(&I);
6996 if (!PHI) break;
6997 auto *StartCST = getOtherIncomingValue(PHI, Latch);
6998 if (!StartCST) continue;
6999 CurrentIterVals[PHI] = StartCST;
7000 }
7001 if (!CurrentIterVals.count(PN))
7002 return RetVal = nullptr;
7003
7004 Value *BEValue = PN->getIncomingValueForBlock(Latch);
7005
7006 // Execute the loop symbolically to determine the exit value.
7007 if (BEs.getActiveBits() >= 32)
7008 return RetVal = nullptr; // More than 2^32-1 iterations?? Not doing it!
7009
7010 unsigned NumIterations = BEs.getZExtValue(); // must be in range
7011 unsigned IterationNum = 0;
7012 const DataLayout &DL = getDataLayout();
7013 for (; ; ++IterationNum) {
7014 if (IterationNum == NumIterations)
7015 return RetVal = CurrentIterVals[PN]; // Got exit value!
7016
7017 // Compute the value of the PHIs for the next iteration.
7018 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
7019 DenseMap<Instruction *, Constant *> NextIterVals;
7020 Constant *NextPHI =
7021 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7022 if (!NextPHI)
7023 return nullptr; // Couldn't evaluate!
7024 NextIterVals[PN] = NextPHI;
7025
7026 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
7027
7028 // Also evaluate the other PHI nodes. However, we don't get to stop if we
7029 // cease to be able to evaluate one of them or if they stop evolving,
7030 // because that doesn't necessarily prevent us from computing PN.
7031 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
7032 for (const auto &I : CurrentIterVals) {
7033 PHINode *PHI = dyn_cast<PHINode>(I.first);
7034 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
7035 PHIsToCompute.emplace_back(PHI, I.second);
7036 }
7037 // We use two distinct loops because EvaluateExpression may invalidate any
7038 // iterators into CurrentIterVals.
7039 for (const auto &I : PHIsToCompute) {
7040 PHINode *PHI = I.first;
7041 Constant *&NextPHI = NextIterVals[PHI];
7042 if (!NextPHI) { // Not already computed.
7043 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
7044 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7045 }
7046 if (NextPHI != I.second)
7047 StoppedEvolving = false;
7048 }
7049
7050 // If all entries in CurrentIterVals == NextIterVals then we can stop
7051 // iterating, the loop can't continue to change.
7052 if (StoppedEvolving)
7053 return RetVal = CurrentIterVals[PN];
7054
7055 CurrentIterVals.swap(NextIterVals);
7056 }
7057}
7058
7059const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
7060 Value *Cond,
7061 bool ExitWhen) {
7062 PHINode *PN = getConstantEvolvingPHI(Cond, L);
7063 if (!PN) return getCouldNotCompute();
7064
7065 // If the loop is canonicalized, the PHI will have exactly two entries.
7066 // That's the only form we support here.
7067 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
7068
7069 DenseMap<Instruction *, Constant *> CurrentIterVals;
7070 BasicBlock *Header = L->getHeader();
7071 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 7071, __PRETTY_FUNCTION__))
;
7072
7073 BasicBlock *Latch = L->getLoopLatch();
7074 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!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 7074, __PRETTY_FUNCTION__))
;
7075
7076 for (auto &I : *Header) {
7077 PHINode *PHI = dyn_cast<PHINode>(&I);
7078 if (!PHI)
7079 break;
7080 auto *StartCST = getOtherIncomingValue(PHI, Latch);
7081 if (!StartCST) continue;
7082 CurrentIterVals[PHI] = StartCST;
7083 }
7084 if (!CurrentIterVals.count(PN))
7085 return getCouldNotCompute();
7086
7087 // Okay, we find a PHI node that defines the trip count of this loop. Execute
7088 // the loop symbolically to determine when the condition gets a value of
7089 // "ExitWhen".
7090 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
7091 const DataLayout &DL = getDataLayout();
7092 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
7093 auto *CondVal = dyn_cast_or_null<ConstantInt>(
7094 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
7095
7096 // Couldn't symbolically evaluate.
7097 if (!CondVal) return getCouldNotCompute();
7098
7099 if (CondVal->getValue() == uint64_t(ExitWhen)) {
7100 ++NumBruteForceTripCountsComputed;
7101 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
7102 }
7103
7104 // Update all the PHI nodes for the next iteration.
7105 DenseMap<Instruction *, Constant *> NextIterVals;
7106
7107 // Create a list of which PHIs we need to compute. We want to do this before
7108 // calling EvaluateExpression on them because that may invalidate iterators
7109 // into CurrentIterVals.
7110 SmallVector<PHINode *, 8> PHIsToCompute;
7111 for (const auto &I : CurrentIterVals) {
7112 PHINode *PHI = dyn_cast<PHINode>(I.first);
7113 if (!PHI || PHI->getParent() != Header) continue;
7114 PHIsToCompute.push_back(PHI);
7115 }
7116 for (PHINode *PHI : PHIsToCompute) {
7117 Constant *&NextPHI = NextIterVals[PHI];
7118 if (NextPHI) continue; // Already computed!
7119
7120 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
7121 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
7122 }
7123 CurrentIterVals.swap(NextIterVals);
7124 }
7125
7126 // Too many iterations were needed to evaluate.
7127 return getCouldNotCompute();
7128}
7129
7130const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
7131 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
7132 ValuesAtScopes[V];
7133 // Check to see if we've folded this expression at this loop before.
7134 for (auto &LS : Values)
7135 if (LS.first == L)
7136 return LS.second ? LS.second : V;
7137
7138 Values.emplace_back(L, nullptr);
7139
7140 // Otherwise compute it.
7141 const SCEV *C = computeSCEVAtScope(V, L);
7142 for (auto &LS : reverse(ValuesAtScopes[V]))
7143 if (LS.first == L) {
7144 LS.second = C;
7145 break;
7146 }
7147 return C;
7148}
7149
7150/// This builds up a Constant using the ConstantExpr interface. That way, we
7151/// will return Constants for objects which aren't represented by a
7152/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
7153/// Returns NULL if the SCEV isn't representable as a Constant.
7154static Constant *BuildConstantFromSCEV(const SCEV *V) {
7155 switch (static_cast<SCEVTypes>(V->getSCEVType())) {
7156 case scCouldNotCompute:
7157 case scAddRecExpr:
7158 break;
7159 case scConstant:
7160 return cast<SCEVConstant>(V)->getValue();
7161 case scUnknown:
7162 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
7163 case scSignExtend: {
7164 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
7165 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
7166 return ConstantExpr::getSExt(CastOp, SS->getType());
7167 break;
7168 }
7169 case scZeroExtend: {
7170 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
7171 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
7172 return ConstantExpr::getZExt(CastOp, SZ->getType());
7173 break;
7174 }
7175 case scTruncate: {
7176 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
7177 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
7178 return ConstantExpr::getTrunc(CastOp, ST->getType());
7179 break;
7180 }
7181 case scAddExpr: {
7182 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
7183 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
7184 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
7185 unsigned AS = PTy->getAddressSpace();
7186 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
7187 C = ConstantExpr::getBitCast(C, DestPtrTy);
7188 }
7189 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
7190 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
7191 if (!C2) return nullptr;
7192
7193 // First pointer!
7194 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
7195 unsigned AS = C2->getType()->getPointerAddressSpace();
7196 std::swap(C, C2);
7197 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
7198 // The offsets have been converted to bytes. We can add bytes to an
7199 // i8* by GEP with the byte count in the first index.
7200 C = ConstantExpr::getBitCast(C, DestPtrTy);
7201 }
7202
7203 // Don't bother trying to sum two pointers. We probably can't
7204 // statically compute a load that results from it anyway.
7205 if (C2->getType()->isPointerTy())
7206 return nullptr;
7207
7208 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
7209 if (PTy->getElementType()->isStructTy())
7210 C2 = ConstantExpr::getIntegerCast(
7211 C2, Type::getInt32Ty(C->getContext()), true);
7212 C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2);
7213 } else
7214 C = ConstantExpr::getAdd(C, C2);
7215 }
7216 return C;
7217 }
7218 break;
7219 }
7220 case scMulExpr: {
7221 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
7222 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
7223 // Don't bother with pointers at all.
7224 if (C->getType()->isPointerTy()) return nullptr;
7225 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
7226 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
7227 if (!C2 || C2->getType()->isPointerTy()) return nullptr;
7228 C = ConstantExpr::getMul(C, C2);
7229 }
7230 return C;
7231 }
7232 break;
7233 }
7234 case scUDivExpr: {
7235 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
7236 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
7237 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
7238 if (LHS->getType() == RHS->getType())
7239 return ConstantExpr::getUDiv(LHS, RHS);
7240 break;
7241 }
7242 case scSMaxExpr:
7243 case scUMaxExpr:
7244 break; // TODO: smax, umax.
7245 }
7246 return nullptr;
7247}
7248
7249const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
7250 if (isa<SCEVConstant>(V)) return V;
7251
7252 // If this instruction is evolved from a constant-evolving PHI, compute the
7253 // exit value from the loop without using SCEVs.
7254 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
7255 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
7256 const Loop *LI = this->LI[I->getParent()];
7257 if (LI && LI->getParentLoop() == L) // Looking for loop exit value.
7258 if (PHINode *PN = dyn_cast<PHINode>(I))
7259 if (PN->getParent() == LI->getHeader()) {
7260 // Okay, there is no closed form solution for the PHI node. Check
7261 // to see if the loop that contains it has a known backedge-taken
7262 // count. If so, we may be able to force computation of the exit
7263 // value.
7264 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI);
7265 if (const SCEVConstant *BTCC =
7266 dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
7267 // Okay, we know how many times the containing loop executes. If
7268 // this is a constant evolving PHI node, get the final value at
7269 // the specified iteration number.
7270 Constant *RV =
7271 getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI);
7272 if (RV) return getSCEV(RV);
7273 }
7274 }
7275
7276 // Okay, this is an expression that we cannot symbolically evaluate
7277 // into a SCEV. Check to see if it's possible to symbolically evaluate
7278 // the arguments into constants, and if so, try to constant propagate the
7279 // result. This is particularly useful for computing loop exit values.
7280 if (CanConstantFold(I)) {
7281 SmallVector<Constant *, 4> Operands;
7282 bool MadeImprovement = false;
7283 for (Value *Op : I->operands()) {
7284 if (Constant *C = dyn_cast<Constant>(Op)) {
7285 Operands.push_back(C);
7286 continue;
7287 }
7288
7289 // If any of the operands is non-constant and if they are
7290 // non-integer and non-pointer, don't even try to analyze them
7291 // with scev techniques.
7292 if (!isSCEVable(Op->getType()))
7293 return V;
7294
7295 const SCEV *OrigV = getSCEV(Op);
7296 const SCEV *OpV = getSCEVAtScope(OrigV, L);
7297 MadeImprovement |= OrigV != OpV;
7298
7299 Constant *C = BuildConstantFromSCEV(OpV);
7300 if (!C) return V;
7301 if (C->getType() != Op->getType())
7302 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
7303 Op->getType(),
7304 false),
7305 C, Op->getType());
7306 Operands.push_back(C);
7307 }
7308
7309 // Check to see if getSCEVAtScope actually made an improvement.
7310 if (MadeImprovement) {
7311 Constant *C = nullptr;
7312 const DataLayout &DL = getDataLayout();
7313 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
7314 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
7315 Operands[1], DL, &TLI);
7316 else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
7317 if (!LI->isVolatile())
7318 C = ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
7319 } else
7320 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
7321 if (!C) return V;
7322 return getSCEV(C);
7323 }
7324 }
7325 }
7326
7327 // This is some other type of SCEVUnknown, just return it.
7328 return V;
7329 }
7330
7331 if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
7332 // Avoid performing the look-up in the common case where the specified
7333 // expression has no loop-variant portions.
7334 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
7335 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
7336 if (OpAtScope != Comm->getOperand(i)) {
7337 // Okay, at least one of these operands is loop variant but might be
7338 // foldable. Build a new instance of the folded commutative expression.
7339 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
7340 Comm->op_begin()+i);
7341 NewOps.push_back(OpAtScope);
7342
7343 for (++i; i != e; ++i) {
7344 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
7345 NewOps.push_back(OpAtScope);
7346 }
7347 if (isa<SCEVAddExpr>(Comm))
7348 return getAddExpr(NewOps);
7349 if (isa<SCEVMulExpr>(Comm))
7350 return getMulExpr(NewOps);
7351 if (isa<SCEVSMaxExpr>(Comm))
7352 return getSMaxExpr(NewOps);
7353 if (isa<SCEVUMaxExpr>(Comm))
7354 return getUMaxExpr(NewOps);
7355 llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Analysis/ScalarEvolution.cpp"
, 7355)
;
7356 }
7357 }
7358 // If we got here, all operands are loop invariant.
7359 return Comm;
7360 }
7361
7362 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
7363 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
7364 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
7365 if (LHS == Div->getLHS() && RHS == Div->getRHS())
7366 return Div; // must be loop invariant
7367 return getUDivExpr(LHS, RHS);
7368 }
7369
7370 // If this is a loop recurrence for a loop that does not contain L, then we
7371 // are dealing with the final value computed by the loop