Bug Summary

File:lib/Analysis/ScalarEvolution.cpp
Location:line 5564, column 7
Description:Called C++ object pointer is null

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/SmallPtrSet.h"
65#include "llvm/ADT/Statistic.h"
66#include "llvm/Analysis/AssumptionCache.h"
67#include "llvm/Analysis/ConstantFolding.h"
68#include "llvm/Analysis/InstructionSimplify.h"
69#include "llvm/Analysis/LoopInfo.h"
70#include "llvm/Analysis/ScalarEvolutionExpressions.h"
71#include "llvm/Analysis/TargetLibraryInfo.h"
72#include "llvm/Analysis/ValueTracking.h"
73#include "llvm/IR/ConstantRange.h"
74#include "llvm/IR/Constants.h"
75#include "llvm/IR/DataLayout.h"
76#include "llvm/IR/DerivedTypes.h"
77#include "llvm/IR/Dominators.h"
78#include "llvm/IR/GetElementPtrTypeIterator.h"
79#include "llvm/IR/GlobalAlias.h"
80#include "llvm/IR/GlobalVariable.h"
81#include "llvm/IR/InstIterator.h"
82#include "llvm/IR/Instructions.h"
83#include "llvm/IR/LLVMContext.h"
84#include "llvm/IR/Metadata.h"
85#include "llvm/IR/Operator.h"
86#include "llvm/IR/PatternMatch.h"
87#include "llvm/Support/CommandLine.h"
88#include "llvm/Support/Debug.h"
89#include "llvm/Support/ErrorHandling.h"
90#include "llvm/Support/MathExtras.h"
91#include "llvm/Support/raw_ostream.h"
92#include "llvm/Support/SaveAndRestore.h"
93#include <algorithm>
94using namespace llvm;
95
96#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
97
98STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = { "scalar-evolution"
, "Number of trip counts computed with array length", 0, 0 }
99 "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = { "scalar-evolution"
, "Number of trip counts computed with array length", 0, 0 };
100STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = { "scalar-evolution"
, "Number of loops with predictable loop counts", 0, 0 }
101 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = { "scalar-evolution"
, "Number of loops with predictable loop counts", 0, 0 };
102STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = { "scalar-evolution"
, "Number of loops without predictable loop counts", 0, 0 }
103 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = { "scalar-evolution"
, "Number of loops without predictable loop counts", 0, 0 };
104STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = { "scalar-evolution"
, "Number of loops with trip counts computed by force", 0, 0 }
105 "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = { "scalar-evolution"
, "Number of loops with trip counts computed by force", 0, 0 };
106
107static cl::opt<unsigned>
108MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
109 cl::desc("Maximum number of iterations SCEV will "
110 "symbolically execute a constant "
111 "derived loop"),
112 cl::init(100));
113
114// FIXME: Enable this with XDEBUG when the test suite is clean.
115static cl::opt<bool>
116VerifySCEV("verify-scev",
117 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
118static cl::opt<bool>
119 VerifySCEVMap("verify-scev-maps",
120 cl::desc("Verify no dangling value in ScalarEvolution's "
121 "ExprValueMap (slow)"));
122
123//===----------------------------------------------------------------------===//
124// SCEV class definitions
125//===----------------------------------------------------------------------===//
126
127//===----------------------------------------------------------------------===//
128// Implementation of the SCEV class.
129//
130
131LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__))
132void SCEV::dump() const {
133 print(dbgs());
134 dbgs() << '\n';
135}
136
137void SCEV::print(raw_ostream &OS) const {
138 switch (static_cast<SCEVTypes>(getSCEVType())) {
139 case scConstant:
140 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
141 return;
142 case scTruncate: {
143 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
144 const SCEV *Op = Trunc->getOperand();
145 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
146 << *Trunc->getType() << ")";
147 return;
148 }
149 case scZeroExtend: {
150 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
151 const SCEV *Op = ZExt->getOperand();
152 OS << "(zext " << *Op->getType() << " " << *Op << " to "
153 << *ZExt->getType() << ")";
154 return;
155 }
156 case scSignExtend: {
157 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
158 const SCEV *Op = SExt->getOperand();
159 OS << "(sext " << *Op->getType() << " " << *Op << " to "
160 << *SExt->getType() << ")";
161 return;
162 }
163 case scAddRecExpr: {
164 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
165 OS << "{" << *AR->getOperand(0);
166 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
167 OS << ",+," << *AR->getOperand(i);
168 OS << "}<";
169 if (AR->hasNoUnsignedWrap())
170 OS << "nuw><";
171 if (AR->hasNoSignedWrap())
172 OS << "nsw><";
173 if (AR->hasNoSelfWrap() &&
174 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
175 OS << "nw><";
176 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
177 OS << ">";
178 return;
179 }
180 case scAddExpr:
181 case scMulExpr:
182 case scUMaxExpr:
183 case scSMaxExpr: {
184 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
185 const char *OpStr = nullptr;
186 switch (NAry->getSCEVType()) {
187 case scAddExpr: OpStr = " + "; break;
188 case scMulExpr: OpStr = " * "; break;
189 case scUMaxExpr: OpStr = " umax "; break;
190 case scSMaxExpr: OpStr = " smax "; break;
191 }
192 OS << "(";
193 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
194 I != E; ++I) {
195 OS << **I;
196 if (std::next(I) != E)
197 OS << OpStr;
198 }
199 OS << ")";
200 switch (NAry->getSCEVType()) {
201 case scAddExpr:
202 case scMulExpr:
203 if (NAry->hasNoUnsignedWrap())
204 OS << "<nuw>";
205 if (NAry->hasNoSignedWrap())
206 OS << "<nsw>";
207 }
208 return;
209 }
210 case scUDivExpr: {
211 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
212 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
213 return;
214 }
215 case scUnknown: {
216 const SCEVUnknown *U = cast<SCEVUnknown>(this);
217 Type *AllocTy;
218 if (U->isSizeOf(AllocTy)) {
219 OS << "sizeof(" << *AllocTy << ")";
220 return;
221 }
222 if (U->isAlignOf(AllocTy)) {
223 OS << "alignof(" << *AllocTy << ")";
224 return;
225 }
226
227 Type *CTy;
228 Constant *FieldNo;
229 if (U->isOffsetOf(CTy, FieldNo)) {
230 OS << "offsetof(" << *CTy << ", ";
231 FieldNo->printAsOperand(OS, false);
232 OS << ")";
233 return;
234 }
235
236 // Otherwise just print it normally.
237 U->getValue()->printAsOperand(OS, false);
238 return;
239 }
240 case scCouldNotCompute:
241 OS << "***COULDNOTCOMPUTE***";
242 return;
243 }
244 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 244);
245}
246
247Type *SCEV::getType() const {
248 switch (static_cast<SCEVTypes>(getSCEVType())) {
249 case scConstant:
250 return cast<SCEVConstant>(this)->getType();
251 case scTruncate:
252 case scZeroExtend:
253 case scSignExtend:
254 return cast<SCEVCastExpr>(this)->getType();
255 case scAddRecExpr:
256 case scMulExpr:
257 case scUMaxExpr:
258 case scSMaxExpr:
259 return cast<SCEVNAryExpr>(this)->getType();
260 case scAddExpr:
261 return cast<SCEVAddExpr>(this)->getType();
262 case scUDivExpr:
263 return cast<SCEVUDivExpr>(this)->getType();
264 case scUnknown:
265 return cast<SCEVUnknown>(this)->getType();
266 case scCouldNotCompute:
267 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 267);
268 }
269 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 269);
270}
271
272bool SCEV::isZero() const {
273 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
274 return SC->getValue()->isZero();
275 return false;
276}
277
278bool SCEV::isOne() const {
279 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
280 return SC->getValue()->isOne();
281 return false;
282}
283
284bool SCEV::isAllOnesValue() const {
285 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
286 return SC->getValue()->isAllOnesValue();
287 return false;
288}
289
290/// isNonConstantNegative - Return true if the specified scev is negated, but
291/// not a constant.
292bool SCEV::isNonConstantNegative() const {
293 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
294 if (!Mul) return false;
295
296 // If there is a constant factor, it will be first.
297 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
298 if (!SC) return false;
299
300 // Return true if the value is negative, this matches things like (-42 * V).
301 return SC->getAPInt().isNegative();
302}
303
304SCEVCouldNotCompute::SCEVCouldNotCompute() :
305 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}
306
307bool SCEVCouldNotCompute::classof(const SCEV *S) {
308 return S->getSCEVType() == scCouldNotCompute;
309}
310
311const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
312 FoldingSetNodeID ID;
313 ID.AddInteger(scConstant);
314 ID.AddPointer(V);
315 void *IP = nullptr;
316 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
317 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
318 UniqueSCEVs.InsertNode(S, IP);
319 return S;
320}
321
322const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
323 return getConstant(ConstantInt::get(getContext(), Val));
324}
325
326const SCEV *
327ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
328 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
329 return getConstant(ConstantInt::get(ITy, V, isSigned));
330}
331
332SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
333 unsigned SCEVTy, const SCEV *op, Type *ty)
334 : SCEV(ID, SCEVTy), Op(op), Ty(ty) {}
335
336SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
337 const SCEV *op, Type *ty)
338 : SCEVCastExpr(ID, scTruncate, op, ty) {
339 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 341, __PRETTY_FUNCTION__))
340 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 341, __PRETTY_FUNCTION__))
341 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 341, __PRETTY_FUNCTION__));
342}
343
344SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
345 const SCEV *op, Type *ty)
346 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
347 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 349, __PRETTY_FUNCTION__))
348 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 349, __PRETTY_FUNCTION__))
349 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 349, __PRETTY_FUNCTION__));
350}
351
352SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
353 const SCEV *op, Type *ty)
354 : SCEVCastExpr(ID, scSignExtend, op, ty) {
355 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 357, __PRETTY_FUNCTION__))
356 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 357, __PRETTY_FUNCTION__))
357 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 357, __PRETTY_FUNCTION__));
358}
359
360void SCEVUnknown::deleted() {
361 // Clear this SCEVUnknown from various maps.
362 SE->forgetMemoizedResults(this);
363
364 // Remove this SCEVUnknown from the uniquing map.
365 SE->UniqueSCEVs.RemoveNode(this);
366
367 // Release the value.
368 setValPtr(nullptr);
369}
370
371void SCEVUnknown::allUsesReplacedWith(Value *New) {
372 // Clear this SCEVUnknown from various maps.
373 SE->forgetMemoizedResults(this);
374
375 // Remove this SCEVUnknown from the uniquing map.
376 SE->UniqueSCEVs.RemoveNode(this);
377
378 // Update this SCEVUnknown to point to the new value. This is needed
379 // because there may still be outstanding SCEVs which still point to
380 // this SCEVUnknown.
381 setValPtr(New);
382}
383
384bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
385 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
386 if (VCE->getOpcode() == Instruction::PtrToInt)
387 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
388 if (CE->getOpcode() == Instruction::GetElementPtr &&
389 CE->getOperand(0)->isNullValue() &&
390 CE->getNumOperands() == 2)
391 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
392 if (CI->isOne()) {
393 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
394 ->getElementType();
395 return true;
396 }
397
398 return false;
399}
400
401bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
402 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
403 if (VCE->getOpcode() == Instruction::PtrToInt)
404 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
405 if (CE->getOpcode() == Instruction::GetElementPtr &&
406 CE->getOperand(0)->isNullValue()) {
407 Type *Ty =
408 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
409 if (StructType *STy = dyn_cast<StructType>(Ty))
410 if (!STy->isPacked() &&
411 CE->getNumOperands() == 3 &&
412 CE->getOperand(1)->isNullValue()) {
413 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
414 if (CI->isOne() &&
415 STy->getNumElements() == 2 &&
416 STy->getElementType(0)->isIntegerTy(1)) {
417 AllocTy = STy->getElementType(1);
418 return true;
419 }
420 }
421 }
422
423 return false;
424}
425
426bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
427 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
428 if (VCE->getOpcode() == Instruction::PtrToInt)
429 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
430 if (CE->getOpcode() == Instruction::GetElementPtr &&
431 CE->getNumOperands() == 3 &&
432 CE->getOperand(0)->isNullValue() &&
433 CE->getOperand(1)->isNullValue()) {
434 Type *Ty =
435 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
436 // Ignore vector types here so that ScalarEvolutionExpander doesn't
437 // emit getelementptrs that index into vectors.
438 if (Ty->isStructTy() || Ty->isArrayTy()) {
439 CTy = Ty;
440 FieldNo = CE->getOperand(2);
441 return true;
442 }
443 }
444
445 return false;
446}
447
448//===----------------------------------------------------------------------===//
449// SCEV Utilities
450//===----------------------------------------------------------------------===//
451
452namespace {
453/// SCEVComplexityCompare - Return true if the complexity of the LHS is less
454/// than the complexity of the RHS. This comparator is used to canonicalize
455/// expressions.
456class SCEVComplexityCompare {
457 const LoopInfo *const LI;
458public:
459 explicit SCEVComplexityCompare(const LoopInfo *li) : LI(li) {}
460
461 // Return true or false if LHS is less than, or at least RHS, respectively.
462 bool operator()(const SCEV *LHS, const SCEV *RHS) const {
463 return compare(LHS, RHS) < 0;
464 }
465
466 // Return negative, zero, or positive, if LHS is less than, equal to, or
467 // greater than RHS, respectively. A three-way result allows recursive
468 // comparisons to be more efficient.
469 int compare(const SCEV *LHS, const SCEV *RHS) const {
470 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
471 if (LHS == RHS)
472 return 0;
473
474 // Primarily, sort the SCEVs by their getSCEVType().
475 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
476 if (LType != RType)
477 return (int)LType - (int)RType;
478
479 // Aside from the getSCEVType() ordering, the particular ordering
480 // isn't very important except that it's beneficial to be consistent,
481 // so that (a + b) and (b + a) don't end up as different expressions.
482 switch (static_cast<SCEVTypes>(LType)) {
483 case scUnknown: {
484 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
485 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
486
487 // Sort SCEVUnknown values with some loose heuristics. TODO: This is
488 // not as complete as it could be.
489 const Value *LV = LU->getValue(), *RV = RU->getValue();
490
491 // Order pointer values after integer values. This helps SCEVExpander
492 // form GEPs.
493 bool LIsPointer = LV->getType()->isPointerTy(),
494 RIsPointer = RV->getType()->isPointerTy();
495 if (LIsPointer != RIsPointer)
496 return (int)LIsPointer - (int)RIsPointer;
497
498 // Compare getValueID values.
499 unsigned LID = LV->getValueID(),
500 RID = RV->getValueID();
501 if (LID != RID)
502 return (int)LID - (int)RID;
503
504 // Sort arguments by their position.
505 if (const Argument *LA = dyn_cast<Argument>(LV)) {
506 const Argument *RA = cast<Argument>(RV);
507 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
508 return (int)LArgNo - (int)RArgNo;
509 }
510
511 // For instructions, compare their loop depth, and their operand
512 // count. This is pretty loose.
513 if (const Instruction *LInst = dyn_cast<Instruction>(LV)) {
514 const Instruction *RInst = cast<Instruction>(RV);
515
516 // Compare loop depths.
517 const BasicBlock *LParent = LInst->getParent(),
518 *RParent = RInst->getParent();
519 if (LParent != RParent) {
520 unsigned LDepth = LI->getLoopDepth(LParent),
521 RDepth = LI->getLoopDepth(RParent);
522 if (LDepth != RDepth)
523 return (int)LDepth - (int)RDepth;
524 }
525
526 // Compare the number of operands.
527 unsigned LNumOps = LInst->getNumOperands(),
528 RNumOps = RInst->getNumOperands();
529 return (int)LNumOps - (int)RNumOps;
530 }
531
532 return 0;
533 }
534
535 case scConstant: {
536 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
537 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
538
539 // Compare constant values.
540 const APInt &LA = LC->getAPInt();
541 const APInt &RA = RC->getAPInt();
542 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
543 if (LBitWidth != RBitWidth)
544 return (int)LBitWidth - (int)RBitWidth;
545 return LA.ult(RA) ? -1 : 1;
546 }
547
548 case scAddRecExpr: {
549 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
550 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
551
552 // Compare addrec loop depths.
553 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
554 if (LLoop != RLoop) {
555 unsigned LDepth = LLoop->getLoopDepth(),
556 RDepth = RLoop->getLoopDepth();
557 if (LDepth != RDepth)
558 return (int)LDepth - (int)RDepth;
559 }
560
561 // Addrec complexity grows with operand count.
562 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
563 if (LNumOps != RNumOps)
564 return (int)LNumOps - (int)RNumOps;
565
566 // Lexicographically compare.
567 for (unsigned i = 0; i != LNumOps; ++i) {
568 long X = compare(LA->getOperand(i), RA->getOperand(i));
569 if (X != 0)
570 return X;
571 }
572
573 return 0;
574 }
575
576 case scAddExpr:
577 case scMulExpr:
578 case scSMaxExpr:
579 case scUMaxExpr: {
580 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
581 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
582
583 // Lexicographically compare n-ary expressions.
584 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
585 if (LNumOps != RNumOps)
586 return (int)LNumOps - (int)RNumOps;
587
588 for (unsigned i = 0; i != LNumOps; ++i) {
589 if (i >= RNumOps)
590 return 1;
591 long X = compare(LC->getOperand(i), RC->getOperand(i));
592 if (X != 0)
593 return X;
594 }
595 return (int)LNumOps - (int)RNumOps;
596 }
597
598 case scUDivExpr: {
599 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
600 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
601
602 // Lexicographically compare udiv expressions.
603 long X = compare(LC->getLHS(), RC->getLHS());
604 if (X != 0)
605 return X;
606 return compare(LC->getRHS(), RC->getRHS());
607 }
608
609 case scTruncate:
610 case scZeroExtend:
611 case scSignExtend: {
612 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
613 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
614
615 // Compare cast expressions by operand.
616 return compare(LC->getOperand(), RC->getOperand());
617 }
618
619 case scCouldNotCompute:
620 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 620);
621 }
622 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 622);
623 }
624};
625} // end anonymous namespace
626
627/// GroupByComplexity - Given a list of SCEV objects, order them by their
628/// complexity, and group objects of the same complexity together by value.
629/// When this routine is finished, we know that any duplicates in the vector are
630/// consecutive and that complexity is monotonically increasing.
631///
632/// Note that we go take special precautions to ensure that we get deterministic
633/// results from this routine. In other words, we don't want the results of
634/// this to depend on where the addresses of various SCEV objects happened to
635/// land in memory.
636///
637static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
638 LoopInfo *LI) {
639 if (Ops.size() < 2) return; // Noop
640 if (Ops.size() == 2) {
641 // This is the common case, which also happens to be trivially simple.
642 // Special case it.
643 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
644 if (SCEVComplexityCompare(LI)(RHS, LHS))
645 std::swap(LHS, RHS);
646 return;
647 }
648
649 // Do the rough sort by complexity.
650 std::stable_sort(Ops.begin(), Ops.end(), SCEVComplexityCompare(LI));
651
652 // Now that we are sorted by complexity, group elements of the same
653 // complexity. Note that this is, at worst, N^2, but the vector is likely to
654 // be extremely short in practice. Note that we take this approach because we
655 // do not want to depend on the addresses of the objects we are grouping.
656 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
657 const SCEV *S = Ops[i];
658 unsigned Complexity = S->getSCEVType();
659
660 // If there are any objects of the same complexity and same value as this
661 // one, group them.
662 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
663 if (Ops[j] == S) { // Found a duplicate.
664 // Move it to immediately after i'th element.
665 std::swap(Ops[i+1], Ops[j]);
666 ++i; // no need to rescan it.
667 if (i == e-2) return; // Done!
668 }
669 }
670 }
671}
672
673// Returns the size of the SCEV S.
674static inline int sizeOfSCEV(const SCEV *S) {
675 struct FindSCEVSize {
676 int Size;
677 FindSCEVSize() : Size(0) {}
678
679 bool follow(const SCEV *S) {
680 ++Size;
681 // Keep looking at all operands of S.
682 return true;
683 }
684 bool isDone() const {
685 return false;
686 }
687 };
688
689 FindSCEVSize F;
690 SCEVTraversal<FindSCEVSize> ST(F);
691 ST.visitAll(S);
692 return F.Size;
693}
694
695namespace {
696
697struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
698public:
699 // Computes the Quotient and Remainder of the division of Numerator by
700 // Denominator.
701 static void divide(ScalarEvolution &SE, const SCEV *Numerator,
702 const SCEV *Denominator, const SCEV **Quotient,
703 const SCEV **Remainder) {
704 assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV"
) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 704, __PRETTY_FUNCTION__));
705
706 SCEVDivision D(SE, Numerator, Denominator);
707
708 // Check for the trivial case here to avoid having to check for it in the
709 // rest of the code.
710 if (Numerator == Denominator) {
711 *Quotient = D.One;
712 *Remainder = D.Zero;
713 return;
714 }
715
716 if (Numerator->isZero()) {
717 *Quotient = D.Zero;
718 *Remainder = D.Zero;
719 return;
720 }
721
722 // A simple case when N/1. The quotient is N.
723 if (Denominator->isOne()) {
724 *Quotient = Numerator;
725 *Remainder = D.Zero;
726 return;
727 }
728
729 // Split the Denominator when it is a product.
730 if (const SCEVMulExpr *T = dyn_cast<const SCEVMulExpr>(Denominator)) {
731 const SCEV *Q, *R;
732 *Quotient = Numerator;
733 for (const SCEV *Op : T->operands()) {
734 divide(SE, *Quotient, Op, &Q, &R);
735 *Quotient = Q;
736
737 // Bail out when the Numerator is not divisible by one of the terms of
738 // the Denominator.
739 if (!R->isZero()) {
740 *Quotient = D.Zero;
741 *Remainder = Numerator;
742 return;
743 }
744 }
745 *Remainder = D.Zero;
746 return;
747 }
748
749 D.visit(Numerator);
750 *Quotient = D.Quotient;
751 *Remainder = D.Remainder;
752 }
753
754 // Except in the trivial case described above, we do not know how to divide
755 // Expr by Denominator for the following functions with empty implementation.
756 void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
757 void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {}
758 void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {}
759 void visitUDivExpr(const SCEVUDivExpr *Numerator) {}
760 void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {}
761 void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {}
762 void visitUnknown(const SCEVUnknown *Numerator) {}
763 void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {}
764
765 void visitConstant(const SCEVConstant *Numerator) {
766 if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
767 APInt NumeratorVal = Numerator->getAPInt();
768 APInt DenominatorVal = D->getAPInt();
769 uint32_t NumeratorBW = NumeratorVal.getBitWidth();
770 uint32_t DenominatorBW = DenominatorVal.getBitWidth();
771
772 if (NumeratorBW > DenominatorBW)
773 DenominatorVal = DenominatorVal.sext(NumeratorBW);
774 else if (NumeratorBW < DenominatorBW)
775 NumeratorVal = NumeratorVal.sext(DenominatorBW);
776
777 APInt QuotientVal(NumeratorVal.getBitWidth(), 0);
778 APInt RemainderVal(NumeratorVal.getBitWidth(), 0);
779 APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal);
780 Quotient = SE.getConstant(QuotientVal);
781 Remainder = SE.getConstant(RemainderVal);
782 return;
783 }
784 }
785
786 void visitAddRecExpr(const SCEVAddRecExpr *Numerator) {
787 const SCEV *StartQ, *StartR, *StepQ, *StepR;
788 if (!Numerator->isAffine())
789 return cannotDivide(Numerator);
790 divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR);
791 divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR);
792 // Bail out if the types do not match.
793 Type *Ty = Denominator->getType();
794 if (Ty != StartQ->getType() || Ty != StartR->getType() ||
795 Ty != StepQ->getType() || Ty != StepR->getType())
796 return cannotDivide(Numerator);
797 Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(),
798 Numerator->getNoWrapFlags());
799 Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(),
800 Numerator->getNoWrapFlags());
801 }
802
803 void visitAddExpr(const SCEVAddExpr *Numerator) {
804 SmallVector<const SCEV *, 2> Qs, Rs;
805 Type *Ty = Denominator->getType();
806
807 for (const SCEV *Op : Numerator->operands()) {
808 const SCEV *Q, *R;
809 divide(SE, Op, Denominator, &Q, &R);
810
811 // Bail out if types do not match.
812 if (Ty != Q->getType() || Ty != R->getType())
813 return cannotDivide(Numerator);
814
815 Qs.push_back(Q);
816 Rs.push_back(R);
817 }
818
819 if (Qs.size() == 1) {
820 Quotient = Qs[0];
821 Remainder = Rs[0];
822 return;
823 }
824
825 Quotient = SE.getAddExpr(Qs);
826 Remainder = SE.getAddExpr(Rs);
827 }
828
829 void visitMulExpr(const SCEVMulExpr *Numerator) {
830 SmallVector<const SCEV *, 2> Qs;
831 Type *Ty = Denominator->getType();
832
833 bool FoundDenominatorTerm = false;
834 for (const SCEV *Op : Numerator->operands()) {
835 // Bail out if types do not match.
836 if (Ty != Op->getType())
837 return cannotDivide(Numerator);
838
839 if (FoundDenominatorTerm) {
840 Qs.push_back(Op);
841 continue;
842 }
843
844 // Check whether Denominator divides one of the product operands.
845 const SCEV *Q, *R;
846 divide(SE, Op, Denominator, &Q, &R);
847 if (!R->isZero()) {
848 Qs.push_back(Op);
849 continue;
850 }
851
852 // Bail out if types do not match.
853 if (Ty != Q->getType())
854 return cannotDivide(Numerator);
855
856 FoundDenominatorTerm = true;
857 Qs.push_back(Q);
858 }
859
860 if (FoundDenominatorTerm) {
861 Remainder = Zero;
862 if (Qs.size() == 1)
863 Quotient = Qs[0];
864 else
865 Quotient = SE.getMulExpr(Qs);
866 return;
867 }
868
869 if (!isa<SCEVUnknown>(Denominator))
870 return cannotDivide(Numerator);
871
872 // The Remainder is obtained by replacing Denominator by 0 in Numerator.
873 ValueToValueMap RewriteMap;
874 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
875 cast<SCEVConstant>(Zero)->getValue();
876 Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
877
878 if (Remainder->isZero()) {
879 // The Quotient is obtained by replacing Denominator by 1 in Numerator.
880 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
881 cast<SCEVConstant>(One)->getValue();
882 Quotient =
883 SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
884 return;
885 }
886
887 // Quotient is (Numerator - Remainder) divided by Denominator.
888 const SCEV *Q, *R;
889 const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder);
890 // This SCEV does not seem to simplify: fail the division here.
891 if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator))
892 return cannotDivide(Numerator);
893 divide(SE, Diff, Denominator, &Q, &R);
894 if (R != Zero)
895 return cannotDivide(Numerator);
896 Quotient = Q;
897 }
898
899private:
900 SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
901 const SCEV *Denominator)
902 : SE(S), Denominator(Denominator) {
903 Zero = SE.getZero(Denominator->getType());
904 One = SE.getOne(Denominator->getType());
905
906 // We generally do not know how to divide Expr by Denominator. We
907 // initialize the division to a "cannot divide" state to simplify the rest
908 // of the code.
909 cannotDivide(Numerator);
910 }
911
912 // Convenience function for giving up on the division. We set the quotient to
913 // be equal to zero and the remainder to be equal to the numerator.
914 void cannotDivide(const SCEV *Numerator) {
915 Quotient = Zero;
916 Remainder = Numerator;
917 }
918
919 ScalarEvolution &SE;
920 const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
921};
922
923}
924
925//===----------------------------------------------------------------------===//
926// Simple SCEV method implementations
927//===----------------------------------------------------------------------===//
928
929/// BinomialCoefficient - Compute BC(It, K). The result has width W.
930/// Assume, K > 0.
931static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
932 ScalarEvolution &SE,
933 Type *ResultTy) {
934 // Handle the simplest case efficiently.
935 if (K == 1)
936 return SE.getTruncateOrZeroExtend(It, ResultTy);
937
938 // We are using the following formula for BC(It, K):
939 //
940 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
941 //
942 // Suppose, W is the bitwidth of the return value. We must be prepared for
943 // overflow. Hence, we must assure that the result of our computation is
944 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
945 // safe in modular arithmetic.
946 //
947 // However, this code doesn't use exactly that formula; the formula it uses
948 // is something like the following, where T is the number of factors of 2 in
949 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
950 // exponentiation:
951 //
952 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
953 //
954 // This formula is trivially equivalent to the previous formula. However,
955 // this formula can be implemented much more efficiently. The trick is that
956 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
957 // arithmetic. To do exact division in modular arithmetic, all we have
958 // to do is multiply by the inverse. Therefore, this step can be done at
959 // width W.
960 //
961 // The next issue is how to safely do the division by 2^T. The way this
962 // is done is by doing the multiplication step at a width of at least W + T
963 // bits. This way, the bottom W+T bits of the product are accurate. Then,
964 // when we perform the division by 2^T (which is equivalent to a right shift
965 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
966 // truncated out after the division by 2^T.
967 //
968 // In comparison to just directly using the first formula, this technique
969 // is much more efficient; using the first formula requires W * K bits,
970 // but this formula less than W + K bits. Also, the first formula requires
971 // a division step, whereas this formula only requires multiplies and shifts.
972 //
973 // It doesn't matter whether the subtraction step is done in the calculation
974 // width or the input iteration count's width; if the subtraction overflows,
975 // the result must be zero anyway. We prefer here to do it in the width of
976 // the induction variable because it helps a lot for certain cases; CodeGen
977 // isn't smart enough to ignore the overflow, which leads to much less
978 // efficient code if the width of the subtraction is wider than the native
979 // register width.
980 //
981 // (It's possible to not widen at all by pulling out factors of 2 before
982 // the multiplication; for example, K=2 can be calculated as
983 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
984 // extra arithmetic, so it's not an obvious win, and it gets
985 // much more complicated for K > 3.)
986
987 // Protection from insane SCEVs; this bound is conservative,
988 // but it probably doesn't matter.
989 if (K > 1000)
990 return SE.getCouldNotCompute();
991
992 unsigned W = SE.getTypeSizeInBits(ResultTy);
993
994 // Calculate K! / 2^T and T; we divide out the factors of two before
995 // multiplying for calculating K! / 2^T to avoid overflow.
996 // Other overflow doesn't matter because we only care about the bottom
997 // W bits of the result.
998 APInt OddFactorial(W, 1);
999 unsigned T = 1;
1000 for (unsigned i = 3; i <= K; ++i) {
1001 APInt Mult(W, i);
1002 unsigned TwoFactors = Mult.countTrailingZeros();
1003 T += TwoFactors;
1004 Mult = Mult.lshr(TwoFactors);
1005 OddFactorial *= Mult;
1006 }
1007
1008 // We need at least W + T bits for the multiplication step
1009 unsigned CalculationBits = W + T;
1010
1011 // Calculate 2^T, at width T+W.
1012 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1013
1014 // Calculate the multiplicative inverse of K! / 2^T;
1015 // this multiplication factor will perform the exact division by
1016 // K! / 2^T.
1017 APInt Mod = APInt::getSignedMinValue(W+1);
1018 APInt MultiplyFactor = OddFactorial.zext(W+1);
1019 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1020 MultiplyFactor = MultiplyFactor.trunc(W);
1021
1022 // Calculate the product, at width T+W
1023 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1024 CalculationBits);
1025 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1026 for (unsigned i = 1; i != K; ++i) {
1027 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1028 Dividend = SE.getMulExpr(Dividend,
1029 SE.getTruncateOrZeroExtend(S, CalculationTy));
1030 }
1031
1032 // Divide by 2^T
1033 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1034
1035 // Truncate the result, and divide by K! / 2^T.
1036
1037 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1038 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1039}
1040
1041/// evaluateAtIteration - Return the value of this chain of recurrences at
1042/// the specified iteration number. We can evaluate this recurrence by
1043/// multiplying each element in the chain by the binomial coefficient
1044/// corresponding to it. In other words, we can evaluate {A,+,B,+,C,+,D} as:
1045///
1046/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1047///
1048/// where BC(It, k) stands for binomial coefficient.
1049///
1050const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1051 ScalarEvolution &SE) const {
1052 const SCEV *Result = getStart();
1053 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1054 // The computation is correct in the face of overflow provided that the
1055 // multiplication is performed _after_ the evaluation of the binomial
1056 // coefficient.
1057 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1058 if (isa<SCEVCouldNotCompute>(Coeff))
1059 return Coeff;
1060
1061 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1062 }
1063 return Result;
1064}
1065
1066//===----------------------------------------------------------------------===//
1067// SCEV Expression folder implementations
1068//===----------------------------------------------------------------------===//
1069
1070const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
1071 Type *Ty) {
1072 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1073, __PRETTY_FUNCTION__))
1073 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1073, __PRETTY_FUNCTION__));
1074 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1075, __PRETTY_FUNCTION__))
1075 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1075, __PRETTY_FUNCTION__));
1076 Ty = getEffectiveSCEVType(Ty);
1077
1078 FoldingSetNodeID ID;
1079 ID.AddInteger(scTruncate);
1080 ID.AddPointer(Op);
1081 ID.AddPointer(Ty);
1082 void *IP = nullptr;
1083 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1084
1085 // Fold if the operand is constant.
1086 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1087 return getConstant(
1088 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1089
1090 // trunc(trunc(x)) --> trunc(x)
1091 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1092 return getTruncateExpr(ST->getOperand(), Ty);
1093
1094 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1095 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1096 return getTruncateOrSignExtend(SS->getOperand(), Ty);
1097
1098 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1099 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1100 return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
1101
1102 // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can
1103 // eliminate all the truncates, or we replace other casts with truncates.
1104 if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) {
1105 SmallVector<const SCEV *, 4> Operands;
1106 bool hasTrunc = false;
1107 for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) {
1108 const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty);
1109 if (!isa<SCEVCastExpr>(SA->getOperand(i)))
1110 hasTrunc = isa<SCEVTruncateExpr>(S);
1111 Operands.push_back(S);
1112 }
1113 if (!hasTrunc)
1114 return getAddExpr(Operands);
1115 UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
1116 }
1117
1118 // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
1119 // eliminate all the truncates, or we replace other casts with truncates.
1120 if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
1121 SmallVector<const SCEV *, 4> Operands;
1122 bool hasTrunc = false;
1123 for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
1124 const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
1125 if (!isa<SCEVCastExpr>(SM->getOperand(i)))
1126 hasTrunc = isa<SCEVTruncateExpr>(S);
1127 Operands.push_back(S);
1128 }
1129 if (!hasTrunc)
1130 return getMulExpr(Operands);
1131 UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
1132 }
1133
1134 // If the input value is a chrec scev, truncate the chrec's operands.
1135 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1136 SmallVector<const SCEV *, 4> Operands;
1137 for (const SCEV *Op : AddRec->operands())
1138 Operands.push_back(getTruncateExpr(Op, Ty));
1139 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1140 }
1141
1142 // The cast wasn't folded; create an explicit cast node. We can reuse
1143 // the existing insert position since if we get here, we won't have
1144 // made any changes which would invalidate it.
1145 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1146 Op, Ty);
1147 UniqueSCEVs.InsertNode(S, IP);
1148 return S;
1149}
1150
1151// Get the limit of a recurrence such that incrementing by Step cannot cause
1152// signed overflow as long as the value of the recurrence within the
1153// loop does not exceed this limit before incrementing.
1154static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1155 ICmpInst::Predicate *Pred,
1156 ScalarEvolution *SE) {
1157 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1158 if (SE->isKnownPositive(Step)) {
1159 *Pred = ICmpInst::ICMP_SLT;
1160 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1161 SE->getSignedRange(Step).getSignedMax());
1162 }
1163 if (SE->isKnownNegative(Step)) {
1164 *Pred = ICmpInst::ICMP_SGT;
1165 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1166 SE->getSignedRange(Step).getSignedMin());
1167 }
1168 return nullptr;
1169}
1170
1171// Get the limit of a recurrence such that incrementing by Step cannot cause
1172// unsigned overflow as long as the value of the recurrence within the loop does
1173// not exceed this limit before incrementing.
1174static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1175 ICmpInst::Predicate *Pred,
1176 ScalarEvolution *SE) {
1177 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1178 *Pred = ICmpInst::ICMP_ULT;
1179
1180 return SE->getConstant(APInt::getMinValue(BitWidth) -
1181 SE->getUnsignedRange(Step).getUnsignedMax());
1182}
1183
1184namespace {
1185
1186struct ExtendOpTraitsBase {
1187 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *);
1188};
1189
1190// Used to make code generic over signed and unsigned overflow.
1191template <typename ExtendOp> struct ExtendOpTraits {
1192 // Members present:
1193 //
1194 // static const SCEV::NoWrapFlags WrapType;
1195 //
1196 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1197 //
1198 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1199 // ICmpInst::Predicate *Pred,
1200 // ScalarEvolution *SE);
1201};
1202
1203template <>
1204struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1205 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1206
1207 static const GetExtendExprTy GetExtendExpr;
1208
1209 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1210 ICmpInst::Predicate *Pred,
1211 ScalarEvolution *SE) {
1212 return getSignedOverflowLimitForStep(Step, Pred, SE);
1213 }
1214};
1215
1216const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1217 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1218
1219template <>
1220struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1221 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1222
1223 static const GetExtendExprTy GetExtendExpr;
1224
1225 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1226 ICmpInst::Predicate *Pred,
1227 ScalarEvolution *SE) {
1228 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1229 }
1230};
1231
1232const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1233 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1234}
1235
1236// The recurrence AR has been shown to have no signed/unsigned wrap or something
1237// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1238// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1239// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1240// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1241// expression "Step + sext/zext(PreIncAR)" is congruent with
1242// "sext/zext(PostIncAR)"
1243template <typename ExtendOpTy>
1244static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1245 ScalarEvolution *SE) {
1246 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1247 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1248
1249 const Loop *L = AR->getLoop();
1250 const SCEV *Start = AR->getStart();
1251 const SCEV *Step = AR->getStepRecurrence(*SE);
1252
1253 // Check for a simple looking step prior to loop entry.
1254 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1255 if (!SA)
1256 return nullptr;
1257
1258 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1259 // subtraction is expensive. For this purpose, perform a quick and dirty
1260 // difference, by checking for Step in the operand list.
1261 SmallVector<const SCEV *, 4> DiffOps;
1262 for (const SCEV *Op : SA->operands())
1263 if (Op != Step)
1264 DiffOps.push_back(Op);
1265
1266 if (DiffOps.size() == SA->getNumOperands())
1267 return nullptr;
1268
1269 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1270 // `Step`:
1271
1272 // 1. NSW/NUW flags on the step increment.
1273 auto PreStartFlags =
1274 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1275 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1276 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1277 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1278
1279 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1280 // "S+X does not sign/unsign-overflow".
1281 //
1282
1283 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1284 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1285 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1286 return PreStart;
1287
1288 // 2. Direct overflow check on the step operation's expression.
1289 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1290 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1291 const SCEV *OperandExtendedStart =
1292 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy),
1293 (SE->*GetExtendExpr)(Step, WideTy));
1294 if ((SE->*GetExtendExpr)(Start, WideTy) == OperandExtendedStart) {
1295 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1296 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1297 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1298 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1299 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1300 }
1301 return PreStart;
1302 }
1303
1304 // 3. Loop precondition.
1305 ICmpInst::Predicate Pred;
1306 const SCEV *OverflowLimit =
1307 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1308
1309 if (OverflowLimit &&
1310 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1311 return PreStart;
1312
1313 return nullptr;
1314}
1315
1316// Get the normalized zero or sign extended expression for this AddRec's Start.
1317template <typename ExtendOpTy>
1318static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1319 ScalarEvolution *SE) {
1320 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1321
1322 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE);
1323 if (!PreStart)
1324 return (SE->*GetExtendExpr)(AR->getStart(), Ty);
1325
1326 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty),
1327 (SE->*GetExtendExpr)(PreStart, Ty));
1328}
1329
1330// Try to prove away overflow by looking at "nearby" add recurrences. A
1331// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1332// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1333//
1334// Formally:
1335//
1336// {S,+,X} == {S-T,+,X} + T
1337// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1338//
1339// If ({S-T,+,X} + T) does not overflow ... (1)
1340//
1341// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1342//
1343// If {S-T,+,X} does not overflow ... (2)
1344//
1345// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1346// == {Ext(S-T)+Ext(T),+,Ext(X)}
1347//
1348// If (S-T)+T does not overflow ... (3)
1349//
1350// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1351// == {Ext(S),+,Ext(X)} == LHS
1352//
1353// Thus, if (1), (2) and (3) are true for some T, then
1354// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1355//
1356// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1357// does not overflow" restricted to the 0th iteration. Therefore we only need
1358// to check for (1) and (2).
1359//
1360// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1361// is `Delta` (defined below).
1362//
1363template <typename ExtendOpTy>
1364bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1365 const SCEV *Step,
1366 const Loop *L) {
1367 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1368
1369 // We restrict `Start` to a constant to prevent SCEV from spending too much
1370 // time here. It is correct (but more expensive) to continue with a
1371 // non-constant `Start` and do a general SCEV subtraction to compute
1372 // `PreStart` below.
1373 //
1374 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1375 if (!StartC)
1376 return false;
1377
1378 APInt StartAI = StartC->getAPInt();
1379
1380 for (unsigned Delta : {-2, -1, 1, 2}) {
1381 const SCEV *PreStart = getConstant(StartAI - Delta);
1382
1383 FoldingSetNodeID ID;
1384 ID.AddInteger(scAddRecExpr);
1385 ID.AddPointer(PreStart);
1386 ID.AddPointer(Step);
1387 ID.AddPointer(L);
1388 void *IP = nullptr;
1389 const auto *PreAR =
1390 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1391
1392 // Give up if we don't already have the add recurrence we need because
1393 // actually constructing an add recurrence is relatively expensive.
1394 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1395 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1396 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1397 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1398 DeltaS, &Pred, this);
1399 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1400 return true;
1401 }
1402 }
1403
1404 return false;
1405}
1406
1407const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op,
1408 Type *Ty) {
1409 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1410, __PRETTY_FUNCTION__))
1410 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1410, __PRETTY_FUNCTION__));
1411 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1412, __PRETTY_FUNCTION__))
1412 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1412, __PRETTY_FUNCTION__));
1413 Ty = getEffectiveSCEVType(Ty);
1414
1415 // Fold if the operand is constant.
1416 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1417 return getConstant(
1418 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1419
1420 // zext(zext(x)) --> zext(x)
1421 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1422 return getZeroExtendExpr(SZ->getOperand(), Ty);
1423
1424 // Before doing any expensive analysis, check to see if we've already
1425 // computed a SCEV for this Op and Ty.
1426 FoldingSetNodeID ID;
1427 ID.AddInteger(scZeroExtend);
1428 ID.AddPointer(Op);
1429 ID.AddPointer(Ty);
1430 void *IP = nullptr;
1431 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1432
1433 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1434 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1435 // It's possible the bits taken off by the truncate were all zero bits. If
1436 // so, we should be able to simplify this further.
1437 const SCEV *X = ST->getOperand();
1438 ConstantRange CR = getUnsignedRange(X);
1439 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1440 unsigned NewBits = getTypeSizeInBits(Ty);
1441 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1442 CR.zextOrTrunc(NewBits)))
1443 return getTruncateOrZeroExtend(X, Ty);
1444 }
1445
1446 // If the input value is a chrec scev, and we can prove that the value
1447 // did not overflow the old, smaller, value, we can zero extend all of the
1448 // operands (often constants). This allows analysis of something like
1449 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1450 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1451 if (AR->isAffine()) {
1452 const SCEV *Start = AR->getStart();
1453 const SCEV *Step = AR->getStepRecurrence(*this);
1454 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1455 const Loop *L = AR->getLoop();
1456
1457 if (!AR->hasNoUnsignedWrap()) {
1458 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1459 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1460 }
1461
1462 // If we have special knowledge that this addrec won't overflow,
1463 // we don't need to do any further analysis.
1464 if (AR->hasNoUnsignedWrap())
1465 return getAddRecExpr(
1466 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1467 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1468
1469 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1470 // Note that this serves two purposes: It filters out loops that are
1471 // simply not analyzable, and it covers the case where this code is
1472 // being called from within backedge-taken count analysis, such that
1473 // attempting to ask for the backedge-taken count would likely result
1474 // in infinite recursion. In the later case, the analysis code will
1475 // cope with a conservative value, and it will take care to purge
1476 // that value once it has finished.
1477 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1478 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1479 // Manually compute the final value for AR, checking for
1480 // overflow.
1481
1482 // Check whether the backedge-taken count can be losslessly casted to
1483 // the addrec's type. The count is always unsigned.
1484 const SCEV *CastedMaxBECount =
1485 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1486 const SCEV *RecastedMaxBECount =
1487 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1488 if (MaxBECount == RecastedMaxBECount) {
1489 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1490 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1491 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step);
1492 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul), WideTy);
1493 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy);
1494 const SCEV *WideMaxBECount =
1495 getZeroExtendExpr(CastedMaxBECount, WideTy);
1496 const SCEV *OperandExtendedAdd =
1497 getAddExpr(WideStart,
1498 getMulExpr(WideMaxBECount,
1499 getZeroExtendExpr(Step, WideTy)));
1500 if (ZAdd == OperandExtendedAdd) {
1501 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1502 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1503 // Return the expression with the addrec on the outside.
1504 return getAddRecExpr(
1505 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1506 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1507 }
1508 // Similar to above, only this time treat the step value as signed.
1509 // This covers loops that count down.
1510 OperandExtendedAdd =
1511 getAddExpr(WideStart,
1512 getMulExpr(WideMaxBECount,
1513 getSignExtendExpr(Step, WideTy)));
1514 if (ZAdd == OperandExtendedAdd) {
1515 // Cache knowledge of AR NW, which is propagated to this AddRec.
1516 // Negative step causes unsigned wrap, but it still can't self-wrap.
1517 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1518 // Return the expression with the addrec on the outside.
1519 return getAddRecExpr(
1520 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1521 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1522 }
1523 }
1524
1525 // If the backedge is guarded by a comparison with the pre-inc value
1526 // the addrec is safe. Also, if the entry is guarded by a comparison
1527 // with the start value and the backedge is guarded by a comparison
1528 // with the post-inc value, the addrec is safe.
1529 if (isKnownPositive(Step)) {
1530 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1531 getUnsignedRange(Step).getUnsignedMax());
1532 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1533 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
1534 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
1535 AR->getPostIncExpr(*this), N))) {
1536 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1537 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1538 // Return the expression with the addrec on the outside.
1539 return getAddRecExpr(
1540 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1541 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1542 }
1543 } else if (isKnownNegative(Step)) {
1544 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1545 getSignedRange(Step).getSignedMin());
1546 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1547 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) &&
1548 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
1549 AR->getPostIncExpr(*this), N))) {
1550 // Cache knowledge of AR NW, which is propagated to this AddRec.
1551 // Negative step causes unsigned wrap, but it still can't self-wrap.
1552 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1553 // Return the expression with the addrec on the outside.
1554 return getAddRecExpr(
1555 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1556 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1557 }
1558 }
1559 }
1560
1561 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1562 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1563 return getAddRecExpr(
1564 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1565 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1566 }
1567 }
1568
1569 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1570 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1571 if (SA->hasNoUnsignedWrap()) {
1572 // If the addition does not unsign overflow then we can, by definition,
1573 // commute the zero extension with the addition operation.
1574 SmallVector<const SCEV *, 4> Ops;
1575 for (const auto *Op : SA->operands())
1576 Ops.push_back(getZeroExtendExpr(Op, Ty));
1577 return getAddExpr(Ops, SCEV::FlagNUW);
1578 }
1579 }
1580
1581 // The cast wasn't folded; create an explicit cast node.
1582 // Recompute the insert position, as it may have been invalidated.
1583 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1584 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1585 Op, Ty);
1586 UniqueSCEVs.InsertNode(S, IP);
1587 return S;
1588}
1589
1590const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
1591 Type *Ty) {
1592 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1593, __PRETTY_FUNCTION__))
1593 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1593, __PRETTY_FUNCTION__));
1594 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1595, __PRETTY_FUNCTION__))
1595 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1595, __PRETTY_FUNCTION__));
1596 Ty = getEffectiveSCEVType(Ty);
1597
1598 // Fold if the operand is constant.
1599 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1600 return getConstant(
1601 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1602
1603 // sext(sext(x)) --> sext(x)
1604 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1605 return getSignExtendExpr(SS->getOperand(), Ty);
1606
1607 // sext(zext(x)) --> zext(x)
1608 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1609 return getZeroExtendExpr(SZ->getOperand(), Ty);
1610
1611 // Before doing any expensive analysis, check to see if we've already
1612 // computed a SCEV for this Op and Ty.
1613 FoldingSetNodeID ID;
1614 ID.AddInteger(scSignExtend);
1615 ID.AddPointer(Op);
1616 ID.AddPointer(Ty);
1617 void *IP = nullptr;
1618 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1619
1620 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1621 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1622 // It's possible the bits taken off by the truncate were all sign bits. If
1623 // so, we should be able to simplify this further.
1624 const SCEV *X = ST->getOperand();
1625 ConstantRange CR = getSignedRange(X);
1626 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1627 unsigned NewBits = getTypeSizeInBits(Ty);
1628 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1629 CR.sextOrTrunc(NewBits)))
1630 return getTruncateOrSignExtend(X, Ty);
1631 }
1632
1633 // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2
1634 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1635 if (SA->getNumOperands() == 2) {
1636 auto *SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0));
1637 auto *SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1));
1638 if (SMul && SC1) {
1639 if (auto *SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) {
1640 const APInt &C1 = SC1->getAPInt();
1641 const APInt &C2 = SC2->getAPInt();
1642 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
1643 C2.ugt(C1) && C2.isPowerOf2())
1644 return getAddExpr(getSignExtendExpr(SC1, Ty),
1645 getSignExtendExpr(SMul, Ty));
1646 }
1647 }
1648 }
1649
1650 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1651 if (SA->hasNoSignedWrap()) {
1652 // If the addition does not sign overflow then we can, by definition,
1653 // commute the sign extension with the addition operation.
1654 SmallVector<const SCEV *, 4> Ops;
1655 for (const auto *Op : SA->operands())
1656 Ops.push_back(getSignExtendExpr(Op, Ty));
1657 return getAddExpr(Ops, SCEV::FlagNSW);
1658 }
1659 }
1660 // If the input value is a chrec scev, and we can prove that the value
1661 // did not overflow the old, smaller, value, we can sign extend all of the
1662 // operands (often constants). This allows analysis of something like
1663 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1664 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1665 if (AR->isAffine()) {
1666 const SCEV *Start = AR->getStart();
1667 const SCEV *Step = AR->getStepRecurrence(*this);
1668 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1669 const Loop *L = AR->getLoop();
1670
1671 if (!AR->hasNoSignedWrap()) {
1672 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1673 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1674 }
1675
1676 // If we have special knowledge that this addrec won't overflow,
1677 // we don't need to do any further analysis.
1678 if (AR->hasNoSignedWrap())
1679 return getAddRecExpr(
1680 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1681 getSignExtendExpr(Step, Ty), L, SCEV::FlagNSW);
1682
1683 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1684 // Note that this serves two purposes: It filters out loops that are
1685 // simply not analyzable, and it covers the case where this code is
1686 // being called from within backedge-taken count analysis, such that
1687 // attempting to ask for the backedge-taken count would likely result
1688 // in infinite recursion. In the later case, the analysis code will
1689 // cope with a conservative value, and it will take care to purge
1690 // that value once it has finished.
1691 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1692 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1693 // Manually compute the final value for AR, checking for
1694 // overflow.
1695
1696 // Check whether the backedge-taken count can be losslessly casted to
1697 // the addrec's type. The count is always unsigned.
1698 const SCEV *CastedMaxBECount =
1699 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1700 const SCEV *RecastedMaxBECount =
1701 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1702 if (MaxBECount == RecastedMaxBECount) {
1703 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1704 // Check whether Start+Step*MaxBECount has no signed overflow.
1705 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
1706 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul), WideTy);
1707 const SCEV *WideStart = getSignExtendExpr(Start, WideTy);
1708 const SCEV *WideMaxBECount =
1709 getZeroExtendExpr(CastedMaxBECount, WideTy);
1710 const SCEV *OperandExtendedAdd =
1711 getAddExpr(WideStart,
1712 getMulExpr(WideMaxBECount,
1713 getSignExtendExpr(Step, WideTy)));
1714 if (SAdd == OperandExtendedAdd) {
1715 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1716 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1717 // Return the expression with the addrec on the outside.
1718 return getAddRecExpr(
1719 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1720 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1721 }
1722 // Similar to above, only this time treat the step value as unsigned.
1723 // This covers loops that count up with an unsigned step.
1724 OperandExtendedAdd =
1725 getAddExpr(WideStart,
1726 getMulExpr(WideMaxBECount,
1727 getZeroExtendExpr(Step, WideTy)));
1728 if (SAdd == OperandExtendedAdd) {
1729 // If AR wraps around then
1730 //
1731 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
1732 // => SAdd != OperandExtendedAdd
1733 //
1734 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
1735 // (SAdd == OperandExtendedAdd => AR is NW)
1736
1737 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1738
1739 // Return the expression with the addrec on the outside.
1740 return getAddRecExpr(
1741 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1742 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1743 }
1744 }
1745
1746 // If the backedge is guarded by a comparison with the pre-inc value
1747 // the addrec is safe. Also, if the entry is guarded by a comparison
1748 // with the start value and the backedge is guarded by a comparison
1749 // with the post-inc value, the addrec is safe.
1750 ICmpInst::Predicate Pred;
1751 const SCEV *OverflowLimit =
1752 getSignedOverflowLimitForStep(Step, &Pred, this);
1753 if (OverflowLimit &&
1754 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
1755 (isLoopEntryGuardedByCond(L, Pred, Start, OverflowLimit) &&
1756 isLoopBackedgeGuardedByCond(L, Pred, AR->getPostIncExpr(*this),
1757 OverflowLimit)))) {
1758 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
1759 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1760 return getAddRecExpr(
1761 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1762 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1763 }
1764 }
1765 // If Start and Step are constants, check if we can apply this
1766 // transformation:
1767 // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2
1768 auto *SC1 = dyn_cast<SCEVConstant>(Start);
1769 auto *SC2 = dyn_cast<SCEVConstant>(Step);
1770 if (SC1 && SC2) {
1771 const APInt &C1 = SC1->getAPInt();
1772 const APInt &C2 = SC2->getAPInt();
1773 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) &&
1774 C2.isPowerOf2()) {
1775 Start = getSignExtendExpr(Start, Ty);
1776 const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L,
1777 AR->getNoWrapFlags());
1778 return getAddExpr(Start, getSignExtendExpr(NewAR, Ty));
1779 }
1780 }
1781
1782 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
1783 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1784 return getAddRecExpr(
1785 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1786 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1787 }
1788 }
1789
1790 // If the input value is provably positive and we could not simplify
1791 // away the sext build a zext instead.
1792 if (isKnownNonNegative(Op))
1793 return getZeroExtendExpr(Op, Ty);
1794
1795 // The cast wasn't folded; create an explicit cast node.
1796 // Recompute the insert position, as it may have been invalidated.
1797 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1798 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1799 Op, Ty);
1800 UniqueSCEVs.InsertNode(S, IP);
1801 return S;
1802}
1803
1804/// getAnyExtendExpr - Return a SCEV for the given operand extended with
1805/// unspecified bits out to the given type.
1806///
1807const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
1808 Type *Ty) {
1809 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1810, __PRETTY_FUNCTION__))
1810 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1810, __PRETTY_FUNCTION__));
1811 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1812, __PRETTY_FUNCTION__))
1812 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1812, __PRETTY_FUNCTION__));
1813 Ty = getEffectiveSCEVType(Ty);
1814
1815 // Sign-extend negative constants.
1816 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1817 if (SC->getAPInt().isNegative())
1818 return getSignExtendExpr(Op, Ty);
1819
1820 // Peel off a truncate cast.
1821 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
1822 const SCEV *NewOp = T->getOperand();
1823 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
1824 return getAnyExtendExpr(NewOp, Ty);
1825 return getTruncateOrNoop(NewOp, Ty);
1826 }
1827
1828 // Next try a zext cast. If the cast is folded, use it.
1829 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
1830 if (!isa<SCEVZeroExtendExpr>(ZExt))
1831 return ZExt;
1832
1833 // Next try a sext cast. If the cast is folded, use it.
1834 const SCEV *SExt = getSignExtendExpr(Op, Ty);
1835 if (!isa<SCEVSignExtendExpr>(SExt))
1836 return SExt;
1837
1838 // Force the cast to be folded into the operands of an addrec.
1839 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
1840 SmallVector<const SCEV *, 4> Ops;
1841 for (const SCEV *Op : AR->operands())
1842 Ops.push_back(getAnyExtendExpr(Op, Ty));
1843 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
1844 }
1845
1846 // If the expression is obviously signed, use the sext cast value.
1847 if (isa<SCEVSMaxExpr>(Op))
1848 return SExt;
1849
1850 // Absent any other information, use the zext cast value.
1851 return ZExt;
1852}
1853
1854/// CollectAddOperandsWithScales - Process the given Ops list, which is
1855/// a list of operands to be added under the given scale, update the given
1856/// map. This is a helper function for getAddRecExpr. As an example of
1857/// what it does, given a sequence of operands that would form an add
1858/// expression like this:
1859///
1860/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
1861///
1862/// where A and B are constants, update the map with these values:
1863///
1864/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
1865///
1866/// and add 13 + A*B*29 to AccumulatedConstant.
1867/// This will allow getAddRecExpr to produce this:
1868///
1869/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
1870///
1871/// This form often exposes folding opportunities that are hidden in
1872/// the original operand list.
1873///
1874/// Return true iff it appears that any interesting folding opportunities
1875/// may be exposed. This helps getAddRecExpr short-circuit extra work in
1876/// the common case where no interesting opportunities are present, and
1877/// is also used as a check to avoid infinite recursion.
1878///
1879static bool
1880CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
1881 SmallVectorImpl<const SCEV *> &NewOps,
1882 APInt &AccumulatedConstant,
1883 const SCEV *const *Ops, size_t NumOperands,
1884 const APInt &Scale,
1885 ScalarEvolution &SE) {
1886 bool Interesting = false;
1887
1888 // Iterate over the add operands. They are sorted, with constants first.
1889 unsigned i = 0;
1890 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
1891 ++i;
1892 // Pull a buried constant out to the outside.
1893 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
1894 Interesting = true;
1895 AccumulatedConstant += Scale * C->getAPInt();
1896 }
1897
1898 // Next comes everything else. We're especially interested in multiplies
1899 // here, but they're in the middle, so just visit the rest with one loop.
1900 for (; i != NumOperands; ++i) {
1901 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
1902 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
1903 APInt NewScale =
1904 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
1905 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
1906 // A multiplication of a constant with another add; recurse.
1907 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
1908 Interesting |=
1909 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
1910 Add->op_begin(), Add->getNumOperands(),
1911 NewScale, SE);
1912 } else {
1913 // A multiplication of a constant with some other value. Update
1914 // the map.
1915 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
1916 const SCEV *Key = SE.getMulExpr(MulOps);
1917 auto Pair = M.insert({Key, NewScale});
1918 if (Pair.second) {
1919 NewOps.push_back(Pair.first->first);
1920 } else {
1921 Pair.first->second += NewScale;
1922 // The map already had an entry for this value, which may indicate
1923 // a folding opportunity.
1924 Interesting = true;
1925 }
1926 }
1927 } else {
1928 // An ordinary operand. Update the map.
1929 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
1930 M.insert({Ops[i], Scale});
1931 if (Pair.second) {
1932 NewOps.push_back(Pair.first->first);
1933 } else {
1934 Pair.first->second += Scale;
1935 // The map already had an entry for this value, which may indicate
1936 // a folding opportunity.
1937 Interesting = true;
1938 }
1939 }
1940 }
1941
1942 return Interesting;
1943}
1944
1945// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
1946// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
1947// can't-overflow flags for the operation if possible.
1948static SCEV::NoWrapFlags
1949StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
1950 const SmallVectorImpl<const SCEV *> &Ops,
1951 SCEV::NoWrapFlags Flags) {
1952 using namespace std::placeholders;
1953 typedef OverflowingBinaryOperator OBO;
1954
1955 bool CanAnalyze =
1956 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
1957 (void)CanAnalyze;
1958 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 1958, __PRETTY_FUNCTION__));
1959
1960 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
1961 SCEV::NoWrapFlags SignOrUnsignWrap =
1962 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
1963
1964 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
1965 auto IsKnownNonNegative = [&](const SCEV *S) {
1966 return SE->isKnownNonNegative(S);
1967 };
1968
1969 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
1970 Flags =
1971 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
1972
1973 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
1974
1975 if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr &&
1976 Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) {
1977
1978 // (A + C) --> (A + C)<nsw> if the addition does not sign overflow
1979 // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow
1980
1981 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
1982 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
1983 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
1984 Instruction::Add, C, OBO::NoSignedWrap);
1985 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
1986 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
1987 }
1988 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
1989 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
1990 Instruction::Add, C, OBO::NoUnsignedWrap);
1991 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
1992 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
1993 }
1994 }
1995
1996 return Flags;
1997}
1998
1999/// getAddExpr - Get a canonical add expression, or something simpler if
2000/// possible.
2001const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2002 SCEV::NoWrapFlags Flags) {
2003 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2004, __PRETTY_FUNCTION__))
2004 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2004, __PRETTY_FUNCTION__));
2005 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2005, __PRETTY_FUNCTION__));
2006 if (Ops.size() == 1) return Ops[0];
2007#ifndef NDEBUG
2008 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2009 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2010 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2011, __PRETTY_FUNCTION__))
2011 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2011, __PRETTY_FUNCTION__));
2012#endif
2013
2014 // Sort by complexity, this groups all similar expression types together.
2015 GroupByComplexity(Ops, &LI);
2016
2017 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2018
2019 // If there are any constants, fold them together.
2020 unsigned Idx = 0;
2021 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2022 ++Idx;
2023 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2023, __PRETTY_FUNCTION__));
2024 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2025 // We found two constants, fold them together!
2026 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2027 if (Ops.size() == 2) return Ops[0];
2028 Ops.erase(Ops.begin()+1); // Erase the folded element
2029 LHSC = cast<SCEVConstant>(Ops[0]);
2030 }
2031
2032 // If we are left with a constant zero being added, strip it off.
2033 if (LHSC->getValue()->isZero()) {
2034 Ops.erase(Ops.begin());
2035 --Idx;
2036 }
2037
2038 if (Ops.size() == 1) return Ops[0];
2039 }
2040
2041 // Okay, check to see if the same value occurs in the operand list more than
2042 // once. If so, merge them together into an multiply expression. Since we
2043 // sorted the list, these values are required to be adjacent.
2044 Type *Ty = Ops[0]->getType();
2045 bool FoundMatch = false;
2046 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2047 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2048 // Scan ahead to count how many equal operands there are.
2049 unsigned Count = 2;
2050 while (i+Count != e && Ops[i+Count] == Ops[i])
2051 ++Count;
2052 // Merge the values into a multiply.
2053 const SCEV *Scale = getConstant(Ty, Count);
2054 const SCEV *Mul = getMulExpr(Scale, Ops[i]);
2055 if (Ops.size() == Count)
2056 return Mul;
2057 Ops[i] = Mul;
2058 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2059 --i; e -= Count - 1;
2060 FoundMatch = true;
2061 }
2062 if (FoundMatch)
2063 return getAddExpr(Ops, Flags);
2064
2065 // Check for truncates. If all the operands are truncated from the same
2066 // type, see if factoring out the truncate would permit the result to be
2067 // folded. eg., trunc(x) + m*trunc(n) --> trunc(x + trunc(m)*n)
2068 // if the contents of the resulting outer trunc fold to something simple.
2069 for (; Idx < Ops.size() && isa<SCEVTruncateExpr>(Ops[Idx]); ++Idx) {
2070 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(Ops[Idx]);
2071 Type *DstType = Trunc->getType();
2072 Type *SrcType = Trunc->getOperand()->getType();
2073 SmallVector<const SCEV *, 8> LargeOps;
2074 bool Ok = true;
2075 // Check all the operands to see if they can be represented in the
2076 // source type of the truncate.
2077 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2078 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2079 if (T->getOperand()->getType() != SrcType) {
2080 Ok = false;
2081 break;
2082 }
2083 LargeOps.push_back(T->getOperand());
2084 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2085 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2086 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2087 SmallVector<const SCEV *, 8> LargeMulOps;
2088 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2089 if (const SCEVTruncateExpr *T =
2090 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2091 if (T->getOperand()->getType() != SrcType) {
2092 Ok = false;
2093 break;
2094 }
2095 LargeMulOps.push_back(T->getOperand());
2096 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2097 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2098 } else {
2099 Ok = false;
2100 break;
2101 }
2102 }
2103 if (Ok)
2104 LargeOps.push_back(getMulExpr(LargeMulOps));
2105 } else {
2106 Ok = false;
2107 break;
2108 }
2109 }
2110 if (Ok) {
2111 // Evaluate the expression in the larger type.
2112 const SCEV *Fold = getAddExpr(LargeOps, Flags);
2113 // If it folds to something simple, use it. Otherwise, don't.
2114 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2115 return getTruncateExpr(Fold, DstType);
2116 }
2117 }
2118
2119 // Skip past any other cast SCEVs.
2120 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2121 ++Idx;
2122
2123 // If there are add operands they would be next.
2124 if (Idx < Ops.size()) {
2125 bool DeletedAdd = false;
2126 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2127 // If we have an add, expand the add operands onto the end of the operands
2128 // list.
2129 Ops.erase(Ops.begin()+Idx);
2130 Ops.append(Add->op_begin(), Add->op_end());
2131 DeletedAdd = true;
2132 }
2133
2134 // If we deleted at least one add, we added operands to the end of the list,
2135 // and they are not necessarily sorted. Recurse to resort and resimplify
2136 // any operands we just acquired.
2137 if (DeletedAdd)
2138 return getAddExpr(Ops);
2139 }
2140
2141 // Skip over the add expression until we get to a multiply.
2142 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2143 ++Idx;
2144
2145 // Check to see if there are any folding opportunities present with
2146 // operands multiplied by constant values.
2147 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2148 uint64_t BitWidth = getTypeSizeInBits(Ty);
2149 DenseMap<const SCEV *, APInt> M;
2150 SmallVector<const SCEV *, 8> NewOps;
2151 APInt AccumulatedConstant(BitWidth, 0);
2152 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2153 Ops.data(), Ops.size(),
2154 APInt(BitWidth, 1), *this)) {
2155 struct APIntCompare {
2156 bool operator()(const APInt &LHS, const APInt &RHS) const {
2157 return LHS.ult(RHS);
2158 }
2159 };
2160
2161 // Some interesting folding opportunity is present, so its worthwhile to
2162 // re-generate the operands list. Group the operands by constant scale,
2163 // to avoid multiplying by the same constant scale multiple times.
2164 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2165 for (const SCEV *NewOp : NewOps)
2166 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2167 // Re-generate the operands list.
2168 Ops.clear();
2169 if (AccumulatedConstant != 0)
2170 Ops.push_back(getConstant(AccumulatedConstant));
2171 for (auto &MulOp : MulOpLists)
2172 if (MulOp.first != 0)
2173 Ops.push_back(getMulExpr(getConstant(MulOp.first),
2174 getAddExpr(MulOp.second)));
2175 if (Ops.empty())
2176 return getZero(Ty);
2177 if (Ops.size() == 1)
2178 return Ops[0];
2179 return getAddExpr(Ops);
2180 }
2181 }
2182
2183 // If we are adding something to a multiply expression, make sure the
2184 // something is not already an operand of the multiply. If so, merge it into
2185 // the multiply.
2186 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2187 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2188 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2189 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2190 if (isa<SCEVConstant>(MulOpSCEV))
2191 continue;
2192 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2193 if (MulOpSCEV == Ops[AddOp]) {
2194 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2195 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2196 if (Mul->getNumOperands() != 2) {
2197 // If the multiply has more than two operands, we must get the
2198 // Y*Z term.
2199 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2200 Mul->op_begin()+MulOp);
2201 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2202 InnerMul = getMulExpr(MulOps);
2203 }
2204 const SCEV *One = getOne(Ty);
2205 const SCEV *AddOne = getAddExpr(One, InnerMul);
2206 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV);
2207 if (Ops.size() == 2) return OuterMul;
2208 if (AddOp < Idx) {
2209 Ops.erase(Ops.begin()+AddOp);
2210 Ops.erase(Ops.begin()+Idx-1);
2211 } else {
2212 Ops.erase(Ops.begin()+Idx);
2213 Ops.erase(Ops.begin()+AddOp-1);
2214 }
2215 Ops.push_back(OuterMul);
2216 return getAddExpr(Ops);
2217 }
2218
2219 // Check this multiply against other multiplies being added together.
2220 for (unsigned OtherMulIdx = Idx+1;
2221 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2222 ++OtherMulIdx) {
2223 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2224 // If MulOp occurs in OtherMul, we can fold the two multiplies
2225 // together.
2226 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2227 OMulOp != e; ++OMulOp)
2228 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2229 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2230 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2231 if (Mul->getNumOperands() != 2) {
2232 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2233 Mul->op_begin()+MulOp);
2234 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2235 InnerMul1 = getMulExpr(MulOps);
2236 }
2237 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2238 if (OtherMul->getNumOperands() != 2) {
2239 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2240 OtherMul->op_begin()+OMulOp);
2241 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2242 InnerMul2 = getMulExpr(MulOps);
2243 }
2244 const SCEV *InnerMulSum = getAddExpr(InnerMul1,InnerMul2);
2245 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum);
2246 if (Ops.size() == 2) return OuterMul;
2247 Ops.erase(Ops.begin()+Idx);
2248 Ops.erase(Ops.begin()+OtherMulIdx-1);
2249 Ops.push_back(OuterMul);
2250 return getAddExpr(Ops);
2251 }
2252 }
2253 }
2254 }
2255
2256 // If there are any add recurrences in the operands list, see if any other
2257 // added values are loop invariant. If so, we can fold them into the
2258 // recurrence.
2259 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2260 ++Idx;
2261
2262 // Scan over all recurrences, trying to fold loop invariants into them.
2263 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2264 // Scan all of the other operands to this add and add them to the vector if
2265 // they are loop invariant w.r.t. the recurrence.
2266 SmallVector<const SCEV *, 8> LIOps;
2267 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2268 const Loop *AddRecLoop = AddRec->getLoop();
2269 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2270 if (isLoopInvariant(Ops[i], AddRecLoop)) {
2271 LIOps.push_back(Ops[i]);
2272 Ops.erase(Ops.begin()+i);
2273 --i; --e;
2274 }
2275
2276 // If we found some loop invariants, fold them into the recurrence.
2277 if (!LIOps.empty()) {
2278 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2279 LIOps.push_back(AddRec->getStart());
2280
2281 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2282 AddRec->op_end());
2283 AddRecOps[0] = getAddExpr(LIOps);
2284
2285 // Build the new addrec. Propagate the NUW and NSW flags if both the
2286 // outer add and the inner addrec are guaranteed to have no overflow.
2287 // Always propagate NW.
2288 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2289 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2290
2291 // If all of the other operands were loop invariant, we are done.
2292 if (Ops.size() == 1) return NewRec;
2293
2294 // Otherwise, add the folded AddRec by the non-invariant parts.
2295 for (unsigned i = 0;; ++i)
2296 if (Ops[i] == AddRec) {
2297 Ops[i] = NewRec;
2298 break;
2299 }
2300 return getAddExpr(Ops);
2301 }
2302
2303 // Okay, if there weren't any loop invariants to be folded, check to see if
2304 // there are multiple AddRec's with the same loop induction variable being
2305 // added together. If so, we can fold them.
2306 for (unsigned OtherIdx = Idx+1;
2307 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2308 ++OtherIdx)
2309 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2310 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2311 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2312 AddRec->op_end());
2313 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2314 ++OtherIdx)
2315 if (const auto *OtherAddRec = dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]))
2316 if (OtherAddRec->getLoop() == AddRecLoop) {
2317 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2318 i != e; ++i) {
2319 if (i >= AddRecOps.size()) {
2320 AddRecOps.append(OtherAddRec->op_begin()+i,
2321 OtherAddRec->op_end());
2322 break;
2323 }
2324 AddRecOps[i] = getAddExpr(AddRecOps[i],
2325 OtherAddRec->getOperand(i));
2326 }
2327 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2328 }
2329 // Step size has changed, so we cannot guarantee no self-wraparound.
2330 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2331 return getAddExpr(Ops);
2332 }
2333
2334 // Otherwise couldn't fold anything into this recurrence. Move onto the
2335 // next one.
2336 }
2337
2338 // Okay, it looks like we really DO need an add expr. Check to see if we
2339 // already have one, otherwise create a new one.
2340 FoldingSetNodeID ID;
2341 ID.AddInteger(scAddExpr);
2342 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2343 ID.AddPointer(Ops[i]);
2344 void *IP = nullptr;
2345 SCEVAddExpr *S =
2346 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2347 if (!S) {
2348 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2349 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2350 S = new (SCEVAllocator) SCEVAddExpr(ID.Intern(SCEVAllocator),
2351 O, Ops.size());
2352 UniqueSCEVs.InsertNode(S, IP);
2353 }
2354 S->setNoWrapFlags(Flags);
2355 return S;
2356}
2357
2358static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2359 uint64_t k = i*j;
2360 if (j > 1 && k / j != i) Overflow = true;
2361 return k;
2362}
2363
2364/// Compute the result of "n choose k", the binomial coefficient. If an
2365/// intermediate computation overflows, Overflow will be set and the return will
2366/// be garbage. Overflow is not cleared on absence of overflow.
2367static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2368 // We use the multiplicative formula:
2369 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2370 // At each iteration, we take the n-th term of the numeral and divide by the
2371 // (k-n)th term of the denominator. This division will always produce an
2372 // integral result, and helps reduce the chance of overflow in the
2373 // intermediate computations. However, we can still overflow even when the
2374 // final result would fit.
2375
2376 if (n == 0 || n == k) return 1;
2377 if (k > n) return 0;
2378
2379 if (k > n/2)
2380 k = n-k;
2381
2382 uint64_t r = 1;
2383 for (uint64_t i = 1; i <= k; ++i) {
2384 r = umul_ov(r, n-(i-1), Overflow);
2385 r /= i;
2386 }
2387 return r;
2388}
2389
2390/// Determine if any of the operands in this SCEV are a constant or if
2391/// any of the add or multiply expressions in this SCEV contain a constant.
2392static bool containsConstantSomewhere(const SCEV *StartExpr) {
2393 SmallVector<const SCEV *, 4> Ops;
2394 Ops.push_back(StartExpr);
2395 while (!Ops.empty()) {
2396 const SCEV *CurrentExpr = Ops.pop_back_val();
2397 if (isa<SCEVConstant>(*CurrentExpr))
2398 return true;
2399
2400 if (isa<SCEVAddExpr>(*CurrentExpr) || isa<SCEVMulExpr>(*CurrentExpr)) {
2401 const auto *CurrentNAry = cast<SCEVNAryExpr>(CurrentExpr);
2402 Ops.append(CurrentNAry->op_begin(), CurrentNAry->op_end());
2403 }
2404 }
2405 return false;
2406}
2407
2408/// getMulExpr - Get a canonical multiply expression, or something simpler if
2409/// possible.
2410const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2411 SCEV::NoWrapFlags Flags) {
2412 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2413, __PRETTY_FUNCTION__))
2413 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2413, __PRETTY_FUNCTION__));
2414 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2414, __PRETTY_FUNCTION__));
2415 if (Ops.size() == 1) return Ops[0];
2416#ifndef NDEBUG
2417 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2418 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2419 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2420, __PRETTY_FUNCTION__))
2420 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2420, __PRETTY_FUNCTION__));
2421#endif
2422
2423 // Sort by complexity, this groups all similar expression types together.
2424 GroupByComplexity(Ops, &LI);
2425
2426 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2427
2428 // If there are any constants, fold them together.
2429 unsigned Idx = 0;
2430 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2431
2432 // C1*(C2+V) -> C1*C2 + C1*V
2433 if (Ops.size() == 2)
2434 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2435 // If any of Add's ops are Adds or Muls with a constant,
2436 // apply this transformation as well.
2437 if (Add->getNumOperands() == 2)
2438 if (containsConstantSomewhere(Add))
2439 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0)),
2440 getMulExpr(LHSC, Add->getOperand(1)));
2441
2442 ++Idx;
2443 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2444 // We found two constants, fold them together!
2445 ConstantInt *Fold =
2446 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2447 Ops[0] = getConstant(Fold);
2448 Ops.erase(Ops.begin()+1); // Erase the folded element
2449 if (Ops.size() == 1) return Ops[0];
2450 LHSC = cast<SCEVConstant>(Ops[0]);
2451 }
2452
2453 // If we are left with a constant one being multiplied, strip it off.
2454 if (cast<SCEVConstant>(Ops[0])->getValue()->equalsInt(1)) {
2455 Ops.erase(Ops.begin());
2456 --Idx;
2457 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2458 // If we have a multiply of zero, it will always be zero.
2459 return Ops[0];
2460 } else if (Ops[0]->isAllOnesValue()) {
2461 // If we have a mul by -1 of an add, try distributing the -1 among the
2462 // add operands.
2463 if (Ops.size() == 2) {
2464 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2465 SmallVector<const SCEV *, 4> NewOps;
2466 bool AnyFolded = false;
2467 for (const SCEV *AddOp : Add->operands()) {
2468 const SCEV *Mul = getMulExpr(Ops[0], AddOp);
2469 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2470 NewOps.push_back(Mul);
2471 }
2472 if (AnyFolded)
2473 return getAddExpr(NewOps);
2474 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2475 // Negation preserves a recurrence's no self-wrap property.
2476 SmallVector<const SCEV *, 4> Operands;
2477 for (const SCEV *AddRecOp : AddRec->operands())
2478 Operands.push_back(getMulExpr(Ops[0], AddRecOp));
2479
2480 return getAddRecExpr(Operands, AddRec->getLoop(),
2481 AddRec->getNoWrapFlags(SCEV::FlagNW));
2482 }
2483 }
2484 }
2485
2486 if (Ops.size() == 1)
2487 return Ops[0];
2488 }
2489
2490 // Skip over the add expression until we get to a multiply.
2491 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2492 ++Idx;
2493
2494 // If there are mul operands inline them all into this expression.
2495 if (Idx < Ops.size()) {
2496 bool DeletedMul = false;
2497 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2498 // If we have an mul, expand the mul operands onto the end of the operands
2499 // list.
2500 Ops.erase(Ops.begin()+Idx);
2501 Ops.append(Mul->op_begin(), Mul->op_end());
2502 DeletedMul = true;
2503 }
2504
2505 // If we deleted at least one mul, we added operands to the end of the list,
2506 // and they are not necessarily sorted. Recurse to resort and resimplify
2507 // any operands we just acquired.
2508 if (DeletedMul)
2509 return getMulExpr(Ops);
2510 }
2511
2512 // If there are any add recurrences in the operands list, see if any other
2513 // added values are loop invariant. If so, we can fold them into the
2514 // recurrence.
2515 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2516 ++Idx;
2517
2518 // Scan over all recurrences, trying to fold loop invariants into them.
2519 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2520 // Scan all of the other operands to this mul and add them to the vector if
2521 // they are loop invariant w.r.t. the recurrence.
2522 SmallVector<const SCEV *, 8> LIOps;
2523 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2524 const Loop *AddRecLoop = AddRec->getLoop();
2525 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2526 if (isLoopInvariant(Ops[i], AddRecLoop)) {
2527 LIOps.push_back(Ops[i]);
2528 Ops.erase(Ops.begin()+i);
2529 --i; --e;
2530 }
2531
2532 // If we found some loop invariants, fold them into the recurrence.
2533 if (!LIOps.empty()) {
2534 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2535 SmallVector<const SCEV *, 4> NewOps;
2536 NewOps.reserve(AddRec->getNumOperands());
2537 const SCEV *Scale = getMulExpr(LIOps);
2538 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2539 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i)));
2540
2541 // Build the new addrec. Propagate the NUW and NSW flags if both the
2542 // outer mul and the inner addrec are guaranteed to have no overflow.
2543 //
2544 // No self-wrap cannot be guaranteed after changing the step size, but
2545 // will be inferred if either NUW or NSW is true.
2546 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
2547 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
2548
2549 // If all of the other operands were loop invariant, we are done.
2550 if (Ops.size() == 1) return NewRec;
2551
2552 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2553 for (unsigned i = 0;; ++i)
2554 if (Ops[i] == AddRec) {
2555 Ops[i] = NewRec;
2556 break;
2557 }
2558 return getMulExpr(Ops);
2559 }
2560
2561 // Okay, if there weren't any loop invariants to be folded, check to see if
2562 // there are multiple AddRec's with the same loop induction variable being
2563 // multiplied together. If so, we can fold them.
2564
2565 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2566 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2567 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2568 // ]]],+,...up to x=2n}.
2569 // Note that the arguments to choose() are always integers with values
2570 // known at compile time, never SCEV objects.
2571 //
2572 // The implementation avoids pointless extra computations when the two
2573 // addrec's are of different length (mathematically, it's equivalent to
2574 // an infinite stream of zeros on the right).
2575 bool OpsModified = false;
2576 for (unsigned OtherIdx = Idx+1;
2577 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2578 ++OtherIdx) {
2579 const SCEVAddRecExpr *OtherAddRec =
2580 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2581 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
2582 continue;
2583
2584 bool Overflow = false;
2585 Type *Ty = AddRec->getType();
2586 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
2587 SmallVector<const SCEV*, 7> AddRecOps;
2588 for (int x = 0, xe = AddRec->getNumOperands() +
2589 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
2590 const SCEV *Term = getZero(Ty);
2591 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
2592 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
2593 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
2594 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
2595 z < ze && !Overflow; ++z) {
2596 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
2597 uint64_t Coeff;
2598 if (LargerThan64Bits)
2599 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
2600 else
2601 Coeff = Coeff1*Coeff2;
2602 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
2603 const SCEV *Term1 = AddRec->getOperand(y-z);
2604 const SCEV *Term2 = OtherAddRec->getOperand(z);
2605 Term = getAddExpr(Term, getMulExpr(CoeffTerm, Term1,Term2));
2606 }
2607 }
2608 AddRecOps.push_back(Term);
2609 }
2610 if (!Overflow) {
2611 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(),
2612 SCEV::FlagAnyWrap);
2613 if (Ops.size() == 2) return NewAddRec;
2614 Ops[Idx] = NewAddRec;
2615 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2616 OpsModified = true;
2617 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
2618 if (!AddRec)
2619 break;
2620 }
2621 }
2622 if (OpsModified)
2623 return getMulExpr(Ops);
2624
2625 // Otherwise couldn't fold anything into this recurrence. Move onto the
2626 // next one.
2627 }
2628
2629 // Okay, it looks like we really DO need an mul expr. Check to see if we
2630 // already have one, otherwise create a new one.
2631 FoldingSetNodeID ID;
2632 ID.AddInteger(scMulExpr);
2633 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2634 ID.AddPointer(Ops[i]);
2635 void *IP = nullptr;
2636 SCEVMulExpr *S =
2637 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2638 if (!S) {
2639 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2640 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2641 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2642 O, Ops.size());
2643 UniqueSCEVs.InsertNode(S, IP);
2644 }
2645 S->setNoWrapFlags(Flags);
2646 return S;
2647}
2648
2649/// getUDivExpr - Get a canonical unsigned division expression, or something
2650/// simpler if possible.
2651const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
2652 const SCEV *RHS) {
2653 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2655, __PRETTY_FUNCTION__))
2654 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2655, __PRETTY_FUNCTION__))
2655 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2655, __PRETTY_FUNCTION__));
2656
2657 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
2658 if (RHSC->getValue()->equalsInt(1))
2659 return LHS; // X udiv 1 --> x
2660 // If the denominator is zero, the result of the udiv is undefined. Don't
2661 // try to analyze it, because the resolution chosen here may differ from
2662 // the resolution chosen in other parts of the compiler.
2663 if (!RHSC->getValue()->isZero()) {
2664 // Determine if the division can be folded into the operands of
2665 // its operands.
2666 // TODO: Generalize this to non-constants by using known-bits information.
2667 Type *Ty = LHS->getType();
2668 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
2669 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
2670 // For non-power-of-two values, effectively round the value up to the
2671 // nearest power of two.
2672 if (!RHSC->getAPInt().isPowerOf2())
2673 ++MaxShiftAmt;
2674 IntegerType *ExtTy =
2675 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
2676 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
2677 if (const SCEVConstant *Step =
2678 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
2679 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
2680 const APInt &StepInt = Step->getAPInt();
2681 const APInt &DivInt = RHSC->getAPInt();
2682 if (!StepInt.urem(DivInt) &&
2683 getZeroExtendExpr(AR, ExtTy) ==
2684 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2685 getZeroExtendExpr(Step, ExtTy),
2686 AR->getLoop(), SCEV::FlagAnyWrap)) {
2687 SmallVector<const SCEV *, 4> Operands;
2688 for (const SCEV *Op : AR->operands())
2689 Operands.push_back(getUDivExpr(Op, RHS));
2690 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
2691 }
2692 /// Get a canonical UDivExpr for a recurrence.
2693 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
2694 // We can currently only fold X%N if X is constant.
2695 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
2696 if (StartC && !DivInt.urem(StepInt) &&
2697 getZeroExtendExpr(AR, ExtTy) ==
2698 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2699 getZeroExtendExpr(Step, ExtTy),
2700 AR->getLoop(), SCEV::FlagAnyWrap)) {
2701 const APInt &StartInt = StartC->getAPInt();
2702 const APInt &StartRem = StartInt.urem(StepInt);
2703 if (StartRem != 0)
2704 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
2705 AR->getLoop(), SCEV::FlagNW);
2706 }
2707 }
2708 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
2709 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
2710 SmallVector<const SCEV *, 4> Operands;
2711 for (const SCEV *Op : M->operands())
2712 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
2713 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
2714 // Find an operand that's safely divisible.
2715 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
2716 const SCEV *Op = M->getOperand(i);
2717 const SCEV *Div = getUDivExpr(Op, RHSC);
2718 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
2719 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
2720 M->op_end());
2721 Operands[i] = Div;
2722 return getMulExpr(Operands);
2723 }
2724 }
2725 }
2726 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
2727 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
2728 SmallVector<const SCEV *, 4> Operands;
2729 for (const SCEV *Op : A->operands())
2730 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
2731 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
2732 Operands.clear();
2733 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
2734 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
2735 if (isa<SCEVUDivExpr>(Op) ||
2736 getMulExpr(Op, RHS) != A->getOperand(i))
2737 break;
2738 Operands.push_back(Op);
2739 }
2740 if (Operands.size() == A->getNumOperands())
2741 return getAddExpr(Operands);
2742 }
2743 }
2744
2745 // Fold if both operands are constant.
2746 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
2747 Constant *LHSCV = LHSC->getValue();
2748 Constant *RHSCV = RHSC->getValue();
2749 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
2750 RHSCV)));
2751 }
2752 }
2753 }
2754
2755 FoldingSetNodeID ID;
2756 ID.AddInteger(scUDivExpr);
2757 ID.AddPointer(LHS);
2758 ID.AddPointer(RHS);
2759 void *IP = nullptr;
2760 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2761 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
2762 LHS, RHS);
2763 UniqueSCEVs.InsertNode(S, IP);
2764 return S;
2765}
2766
2767static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
2768 APInt A = C1->getAPInt().abs();
2769 APInt B = C2->getAPInt().abs();
2770 uint32_t ABW = A.getBitWidth();
2771 uint32_t BBW = B.getBitWidth();
2772
2773 if (ABW > BBW)
2774 B = B.zext(ABW);
2775 else if (ABW < BBW)
2776 A = A.zext(BBW);
2777
2778 return APIntOps::GreatestCommonDivisor(A, B);
2779}
2780
2781/// getUDivExactExpr - Get a canonical unsigned division expression, or
2782/// something simpler if possible. There is no representation for an exact udiv
2783/// in SCEV IR, but we can attempt to remove factors from the LHS and RHS.
2784/// We can't do this when it's not exact because the udiv may be clearing bits.
2785const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
2786 const SCEV *RHS) {
2787 // TODO: we could try to find factors in all sorts of things, but for now we
2788 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
2789 // end of this file for inspiration.
2790
2791 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
2792 if (!Mul)
2793 return getUDivExpr(LHS, RHS);
2794
2795 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
2796 // If the mulexpr multiplies by a constant, then that constant must be the
2797 // first element of the mulexpr.
2798 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
2799 if (LHSCst == RHSCst) {
2800 SmallVector<const SCEV *, 2> Operands;
2801 Operands.append(Mul->op_begin() + 1, Mul->op_end());
2802 return getMulExpr(Operands);
2803 }
2804
2805 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
2806 // that there's a factor provided by one of the other terms. We need to
2807 // check.
2808 APInt Factor = gcd(LHSCst, RHSCst);
2809 if (!Factor.isIntN(1)) {
2810 LHSCst =
2811 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
2812 RHSCst =
2813 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
2814 SmallVector<const SCEV *, 2> Operands;
2815 Operands.push_back(LHSCst);
2816 Operands.append(Mul->op_begin() + 1, Mul->op_end());
2817 LHS = getMulExpr(Operands);
2818 RHS = RHSCst;
2819 Mul = dyn_cast<SCEVMulExpr>(LHS);
2820 if (!Mul)
2821 return getUDivExactExpr(LHS, RHS);
2822 }
2823 }
2824 }
2825
2826 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
2827 if (Mul->getOperand(i) == RHS) {
2828 SmallVector<const SCEV *, 2> Operands;
2829 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
2830 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
2831 return getMulExpr(Operands);
2832 }
2833 }
2834
2835 return getUDivExpr(LHS, RHS);
2836}
2837
2838/// getAddRecExpr - Get an add recurrence expression for the specified loop.
2839/// Simplify the expression as much as possible.
2840const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
2841 const Loop *L,
2842 SCEV::NoWrapFlags Flags) {
2843 SmallVector<const SCEV *, 4> Operands;
2844 Operands.push_back(Start);
2845 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
2846 if (StepChrec->getLoop() == L) {
2847 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
2848 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
2849 }
2850
2851 Operands.push_back(Step);
2852 return getAddRecExpr(Operands, L, Flags);
2853}
2854
2855/// getAddRecExpr - Get an add recurrence expression for the specified loop.
2856/// Simplify the expression as much as possible.
2857const SCEV *
2858ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
2859 const Loop *L, SCEV::NoWrapFlags Flags) {
2860 if (Operands.size() == 1) return Operands[0];
2861#ifndef NDEBUG
2862 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
2863 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
2864 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2865, __PRETTY_FUNCTION__))
2865 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2865, __PRETTY_FUNCTION__));
2866 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
2867 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2868, __PRETTY_FUNCTION__))
2868 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 2868, __PRETTY_FUNCTION__));
2869#endif
2870
2871 if (Operands.back()->isZero()) {
2872 Operands.pop_back();
2873 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
2874 }
2875
2876 // It's tempting to want to call getMaxBackedgeTakenCount count here and
2877 // use that information to infer NUW and NSW flags. However, computing a
2878 // BE count requires calling getAddRecExpr, so we may not yet have a
2879 // meaningful BE count at this point (and if we don't, we'd be stuck
2880 // with a SCEVCouldNotCompute as the cached BE count).
2881
2882 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
2883
2884 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
2885 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
2886 const Loop *NestedLoop = NestedAR->getLoop();
2887 if (L->contains(NestedLoop)
2888 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
2889 : (!NestedLoop->contains(L) &&
2890 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
2891 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
2892 NestedAR->op_end());
2893 Operands[0] = NestedAR->getStart();
2894 // AddRecs require their operands be loop-invariant with respect to their
2895 // loops. Don't perform this transformation if it would break this
2896 // requirement.
2897 bool AllInvariant = all_of(
2898 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
2899
2900 if (AllInvariant) {
2901 // Create a recurrence for the outer loop with the same step size.
2902 //
2903 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
2904 // inner recurrence has the same property.
2905 SCEV::NoWrapFlags OuterFlags =
2906 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
2907
2908 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
2909 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
2910 return isLoopInvariant(Op, NestedLoop);
2911 });
2912
2913 if (AllInvariant) {
2914 // Ok, both add recurrences are valid after the transformation.
2915 //
2916 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
2917 // the outer recurrence has the same property.
2918 SCEV::NoWrapFlags InnerFlags =
2919 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
2920 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
2921 }
2922 }
2923 // Reset Operands to its original state.
2924 Operands[0] = NestedAR;
2925 }
2926 }
2927
2928 // Okay, it looks like we really DO need an addrec expr. Check to see if we
2929 // already have one, otherwise create a new one.
2930 FoldingSetNodeID ID;
2931 ID.AddInteger(scAddRecExpr);
2932 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
2933 ID.AddPointer(Operands[i]);
2934 ID.AddPointer(L);
2935 void *IP = nullptr;
2936 SCEVAddRecExpr *S =
2937 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2938 if (!S) {
2939 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
2940 std::uninitialized_copy(Operands.begin(), Operands.end(), O);
2941 S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator),
2942 O, Operands.size(), L);
2943 UniqueSCEVs.InsertNode(S, IP);
2944 }
2945 S->setNoWrapFlags(Flags);
2946 return S;
2947}
2948
2949const SCEV *
2950ScalarEvolution::getGEPExpr(Type *PointeeType, const SCEV *BaseExpr,
2951 const SmallVectorImpl<const SCEV *> &IndexExprs,
2952 bool InBounds) {
2953 // getSCEV(Base)->getType() has the same address space as Base->getType()
2954 // because SCEV::getType() preserves the address space.
2955 Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType());
2956 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
2957 // instruction to its SCEV, because the Instruction may be guarded by control
2958 // flow and the no-overflow bits may not be valid for the expression in any
2959 // context. This can be fixed similarly to how these flags are handled for
2960 // adds.
2961 SCEV::NoWrapFlags Wrap = InBounds ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
2962
2963 const SCEV *TotalOffset = getZero(IntPtrTy);
2964 // The address space is unimportant. The first thing we do on CurTy is getting
2965 // its element type.
2966 Type *CurTy = PointerType::getUnqual(PointeeType);
2967 for (const SCEV *IndexExpr : IndexExprs) {
2968 // Compute the (potentially symbolic) offset in bytes for this index.
2969 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
2970 // For a struct, add the member offset.
2971 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
2972 unsigned FieldNo = Index->getZExtValue();
2973 const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo);
2974
2975 // Add the field offset to the running total offset.
2976 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
2977
2978 // Update CurTy to the type of the field at Index.
2979 CurTy = STy->getTypeAtIndex(Index);
2980 } else {
2981 // Update CurTy to its element type.
2982 CurTy = cast<SequentialType>(CurTy)->getElementType();
2983 // For an array, add the element offset, explicitly scaled.
2984 const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy);
2985 // Getelementptr indices are signed.
2986 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy);
2987
2988 // Multiply the index by the element size to compute the element offset.
2989 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
2990
2991 // Add the element offset to the running total offset.
2992 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
2993 }
2994 }
2995
2996 // Add the total offset from all the GEP indices to the base.
2997 return getAddExpr(BaseExpr, TotalOffset, Wrap);
2998}
2999
3000const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS,
3001 const SCEV *RHS) {
3002 SmallVector<const SCEV *, 2> Ops;
3003 Ops.push_back(LHS);
3004 Ops.push_back(RHS);
3005 return getSMaxExpr(Ops);
3006}
3007
3008const SCEV *
3009ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3010 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3010, __PRETTY_FUNCTION__));
3011 if (Ops.size() == 1) return Ops[0];
3012#ifndef NDEBUG
3013 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3014 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3015 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3016, __PRETTY_FUNCTION__))
3016 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3016, __PRETTY_FUNCTION__));
3017#endif
3018
3019 // Sort by complexity, this groups all similar expression types together.
3020 GroupByComplexity(Ops, &LI);
3021
3022 // If there are any constants, fold them together.
3023 unsigned Idx = 0;
3024 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3025 ++Idx;
3026 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3026, __PRETTY_FUNCTION__));
3027 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3028 // We found two constants, fold them together!
3029 ConstantInt *Fold = ConstantInt::get(
3030 getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt()));
3031 Ops[0] = getConstant(Fold);
3032 Ops.erase(Ops.begin()+1); // Erase the folded element
3033 if (Ops.size() == 1) return Ops[0];
3034 LHSC = cast<SCEVConstant>(Ops[0]);
3035 }
3036
3037 // If we are left with a constant minimum-int, strip it off.
3038 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
3039 Ops.erase(Ops.begin());
3040 --Idx;
3041 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
3042 // If we have an smax with a constant maximum-int, it will always be
3043 // maximum-int.
3044 return Ops[0];
3045 }
3046
3047 if (Ops.size() == 1) return Ops[0];
3048 }
3049
3050 // Find the first SMax
3051 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
3052 ++Idx;
3053
3054 // Check to see if one of the operands is an SMax. If so, expand its operands
3055 // onto our operand list, and recurse to simplify.
3056 if (Idx < Ops.size()) {
3057 bool DeletedSMax = false;
3058 while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
3059 Ops.erase(Ops.begin()+Idx);
3060 Ops.append(SMax->op_begin(), SMax->op_end());
3061 DeletedSMax = true;
3062 }
3063
3064 if (DeletedSMax)
3065 return getSMaxExpr(Ops);
3066 }
3067
3068 // Okay, check to see if the same value occurs in the operand list twice. If
3069 // so, delete one. Since we sorted the list, these values are required to
3070 // be adjacent.
3071 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3072 // X smax Y smax Y --> X smax Y
3073 // X smax Y --> X, if X is always greater than Y
3074 if (Ops[i] == Ops[i+1] ||
3075 isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
3076 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3077 --i; --e;
3078 } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
3079 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3080 --i; --e;
3081 }
3082
3083 if (Ops.size() == 1) return Ops[0];
3084
3085 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3085, __PRETTY_FUNCTION__));
3086
3087 // Okay, it looks like we really DO need an smax expr. Check to see if we
3088 // already have one, otherwise create a new one.
3089 FoldingSetNodeID ID;
3090 ID.AddInteger(scSMaxExpr);
3091 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3092 ID.AddPointer(Ops[i]);
3093 void *IP = nullptr;
3094 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3095 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3096 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3097 SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
3098 O, Ops.size());
3099 UniqueSCEVs.InsertNode(S, IP);
3100 return S;
3101}
3102
3103const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS,
3104 const SCEV *RHS) {
3105 SmallVector<const SCEV *, 2> Ops;
3106 Ops.push_back(LHS);
3107 Ops.push_back(RHS);
3108 return getUMaxExpr(Ops);
3109}
3110
3111const SCEV *
3112ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3113 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3113, __PRETTY_FUNCTION__));
3114 if (Ops.size() == 1) return Ops[0];
3115#ifndef NDEBUG
3116 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3117 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3118 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3119, __PRETTY_FUNCTION__))
3119 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3119, __PRETTY_FUNCTION__));
3120#endif
3121
3122 // Sort by complexity, this groups all similar expression types together.
3123 GroupByComplexity(Ops, &LI);
3124
3125 // If there are any constants, fold them together.
3126 unsigned Idx = 0;
3127 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3128 ++Idx;
3129 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3129, __PRETTY_FUNCTION__));
3130 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3131 // We found two constants, fold them together!
3132 ConstantInt *Fold = ConstantInt::get(
3133 getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt()));
3134 Ops[0] = getConstant(Fold);
3135 Ops.erase(Ops.begin()+1); // Erase the folded element
3136 if (Ops.size() == 1) return Ops[0];
3137 LHSC = cast<SCEVConstant>(Ops[0]);
3138 }
3139
3140 // If we are left with a constant minimum-int, strip it off.
3141 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
3142 Ops.erase(Ops.begin());
3143 --Idx;
3144 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
3145 // If we have an umax with a constant maximum-int, it will always be
3146 // maximum-int.
3147 return Ops[0];
3148 }
3149
3150 if (Ops.size() == 1) return Ops[0];
3151 }
3152
3153 // Find the first UMax
3154 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
3155 ++Idx;
3156
3157 // Check to see if one of the operands is a UMax. If so, expand its operands
3158 // onto our operand list, and recurse to simplify.
3159 if (Idx < Ops.size()) {
3160 bool DeletedUMax = false;
3161 while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
3162 Ops.erase(Ops.begin()+Idx);
3163 Ops.append(UMax->op_begin(), UMax->op_end());
3164 DeletedUMax = true;
3165 }
3166
3167 if (DeletedUMax)
3168 return getUMaxExpr(Ops);
3169 }
3170
3171 // Okay, check to see if the same value occurs in the operand list twice. If
3172 // so, delete one. Since we sorted the list, these values are required to
3173 // be adjacent.
3174 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3175 // X umax Y umax Y --> X umax Y
3176 // X umax Y --> X, if X is always greater than Y
3177 if (Ops[i] == Ops[i+1] ||
3178 isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
3179 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3180 --i; --e;
3181 } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
3182 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3183 --i; --e;
3184 }
3185
3186 if (Ops.size() == 1) return Ops[0];
3187
3188 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3188, __PRETTY_FUNCTION__));
3189
3190 // Okay, it looks like we really DO need a umax expr. Check to see if we
3191 // already have one, otherwise create a new one.
3192 FoldingSetNodeID ID;
3193 ID.AddInteger(scUMaxExpr);
3194 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3195 ID.AddPointer(Ops[i]);
3196 void *IP = nullptr;
3197 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3198 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3199 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3200 SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
3201 O, Ops.size());
3202 UniqueSCEVs.InsertNode(S, IP);
3203 return S;
3204}
3205
3206const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3207 const SCEV *RHS) {
3208 // ~smax(~x, ~y) == smin(x, y).
3209 return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3210}
3211
3212const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3213 const SCEV *RHS) {
3214 // ~umax(~x, ~y) == umin(x, y)
3215 return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3216}
3217
3218const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3219 // We can bypass creating a target-independent
3220 // constant expression and then folding it back into a ConstantInt.
3221 // This is just a compile-time optimization.
3222 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3223}
3224
3225const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3226 StructType *STy,
3227 unsigned FieldNo) {
3228 // We can bypass creating a target-independent
3229 // constant expression and then folding it back into a ConstantInt.
3230 // This is just a compile-time optimization.
3231 return getConstant(
3232 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3233}
3234
3235const SCEV *ScalarEvolution::getUnknown(Value *V) {
3236 // Don't attempt to do anything other than create a SCEVUnknown object
3237 // here. createSCEV only calls getUnknown after checking for all other
3238 // interesting possibilities, and any other code that calls getUnknown
3239 // is doing so in order to hide a value from SCEV canonicalization.
3240
3241 FoldingSetNodeID ID;
3242 ID.AddInteger(scUnknown);
3243 ID.AddPointer(V);
3244 void *IP = nullptr;
3245 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3246 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3247, __PRETTY_FUNCTION__))
3247 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3247, __PRETTY_FUNCTION__));
3248 return S;
3249 }
3250 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3251 FirstUnknown);
3252 FirstUnknown = cast<SCEVUnknown>(S);
3253 UniqueSCEVs.InsertNode(S, IP);
3254 return S;
3255}
3256
3257//===----------------------------------------------------------------------===//
3258// Basic SCEV Analysis and PHI Idiom Recognition Code
3259//
3260
3261/// isSCEVable - Test if values of the given type are analyzable within
3262/// the SCEV framework. This primarily includes integer types, and it
3263/// can optionally include pointer types if the ScalarEvolution class
3264/// has access to target-specific information.
3265bool ScalarEvolution::isSCEVable(Type *Ty) const {
3266 // Integers and pointers are always SCEVable.
3267 return Ty->isIntegerTy() || Ty->isPointerTy();
3268}
3269
3270/// getTypeSizeInBits - Return the size in bits of the specified type,
3271/// for which isSCEVable must return true.
3272uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3273 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3273, __PRETTY_FUNCTION__));
3274 return getDataLayout().getTypeSizeInBits(Ty);
3275}
3276
3277/// getEffectiveSCEVType - Return a type with the same bitwidth as
3278/// the given type and which represents how SCEV will treat the given
3279/// type, for which isSCEVable must return true. For pointer types,
3280/// this is the pointer-sized integer type.
3281Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3282 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3282, __PRETTY_FUNCTION__));
3283
3284 if (Ty->isIntegerTy())
3285 return Ty;
3286
3287 // The only other support type is pointer.
3288 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3288, __PRETTY_FUNCTION__));
3289 return getDataLayout().getIntPtrType(Ty);
3290}
3291
3292const SCEV *ScalarEvolution::getCouldNotCompute() {
3293 return CouldNotCompute.get();
3294}
3295
3296
3297bool ScalarEvolution::checkValidity(const SCEV *S) const {
3298 // Helper class working with SCEVTraversal to figure out if a SCEV contains
3299 // a SCEVUnknown with null value-pointer. FindInvalidSCEVUnknown::FindOne
3300 // is set iff if find such SCEVUnknown.
3301 //
3302 struct FindInvalidSCEVUnknown {
3303 bool FindOne;
3304 FindInvalidSCEVUnknown() { FindOne = false; }
3305 bool follow(const SCEV *S) {
3306 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
3307 case scConstant:
3308 return false;
3309 case scUnknown:
3310 if (!cast<SCEVUnknown>(S)->getValue())
3311 FindOne = true;
3312 return false;
3313 default:
3314 return true;
3315 }
3316 }
3317 bool isDone() const { return FindOne; }
3318 };
3319
3320 FindInvalidSCEVUnknown F;
3321 SCEVTraversal<FindInvalidSCEVUnknown> ST(F);
3322 ST.visitAll(S);
3323
3324 return !F.FindOne;
3325}
3326
3327namespace {
3328// Helper class working with SCEVTraversal to figure out if a SCEV contains
3329// a sub SCEV of scAddRecExpr type. FindInvalidSCEVUnknown::FoundOne is set
3330// iff if such sub scAddRecExpr type SCEV is found.
3331struct FindAddRecurrence {
3332 bool FoundOne;
3333 FindAddRecurrence() : FoundOne(false) {}
3334
3335 bool follow(const SCEV *S) {
3336 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
3337 case scAddRecExpr:
3338 FoundOne = true;
3339 case scConstant:
3340 case scUnknown:
3341 case scCouldNotCompute:
3342 return false;
3343 default:
3344 return true;
3345 }
3346 }
3347 bool isDone() const { return FoundOne; }
3348};
3349}
3350
3351bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3352 HasRecMapType::iterator I = HasRecMap.find_as(S);
3353 if (I != HasRecMap.end())
3354 return I->second;
3355
3356 FindAddRecurrence F;
3357 SCEVTraversal<FindAddRecurrence> ST(F);
3358 ST.visitAll(S);
3359 HasRecMap.insert({S, F.FoundOne});
3360 return F.FoundOne;
3361}
3362
3363/// getSCEVValues - Return the Value set from S.
3364SetVector<Value *> *ScalarEvolution::getSCEVValues(const SCEV *S) {
3365 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3366 if (SI == ExprValueMap.end())
3367 return nullptr;
3368#ifndef NDEBUG
3369 if (VerifySCEVMap) {
3370 // Check there is no dangling Value in the set returned.
3371 for (const auto &VE : SI->second)
3372 assert(ValueExprMap.count(VE))((ValueExprMap.count(VE)) ? static_cast<void> (0) : __assert_fail
("ValueExprMap.count(VE)", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3372, __PRETTY_FUNCTION__));
3373 }
3374#endif
3375 return &SI->second;
3376}
3377
3378/// eraseValueFromMap - Erase Value from ValueExprMap and ExprValueMap.
3379/// If ValueExprMap.erase(V) is not used together with forgetMemoizedResults(S),
3380/// eraseValueFromMap should be used instead to ensure whenever V->S is removed
3381/// from ValueExprMap, V is also removed from the set of ExprValueMap[S].
3382void ScalarEvolution::eraseValueFromMap(Value *V) {
3383 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3384 if (I != ValueExprMap.end()) {
3385 const SCEV *S = I->second;
3386 SetVector<Value *> *SV = getSCEVValues(S);
3387 // Remove V from the set of ExprValueMap[S]
3388 if (SV)
3389 SV->remove(V);
3390 ValueExprMap.erase(V);
3391 }
3392}
3393
3394/// getSCEV - Return an existing SCEV if it exists, otherwise analyze the
3395/// expression and create a new one.
3396const SCEV *ScalarEvolution::getSCEV(Value *V) {
3397 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3397, __PRETTY_FUNCTION__));
3398
3399 const SCEV *S = getExistingSCEV(V);
3400 if (S == nullptr) {
3401 S = createSCEV(V);
3402 // During PHI resolution, it is possible to create two SCEVs for the same
3403 // V, so it is needed to double check whether V->S is inserted into
3404 // ValueExprMap before insert S->V into ExprValueMap.
3405 std::pair<ValueExprMapType::iterator, bool> Pair =
3406 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3407 if (Pair.second)
3408 ExprValueMap[S].insert(V);
3409 }
3410 return S;
3411}
3412
3413const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3414 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3414, __PRETTY_FUNCTION__));
3415
3416 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3417 if (I != ValueExprMap.end()) {
3418 const SCEV *S = I->second;
3419 if (checkValidity(S))
3420 return S;
3421 forgetMemoizedResults(S);
3422 ValueExprMap.erase(I);
3423 }
3424 return nullptr;
3425}
3426
3427/// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
3428///
3429const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3430 SCEV::NoWrapFlags Flags) {
3431 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3432 return getConstant(
3433 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3434
3435 Type *Ty = V->getType();
3436 Ty = getEffectiveSCEVType(Ty);
3437 return getMulExpr(
3438 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3439}
3440
3441/// getNotSCEV - Return a SCEV corresponding to ~V = -1-V
3442const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3443 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3444 return getConstant(
3445 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3446
3447 Type *Ty = V->getType();
3448 Ty = getEffectiveSCEVType(Ty);
3449 const SCEV *AllOnes =
3450 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3451 return getMinusSCEV(AllOnes, V);
3452}
3453
3454/// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1.
3455const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3456 SCEV::NoWrapFlags Flags) {
3457 // Fast path: X - X --> 0.
3458 if (LHS == RHS)
3459 return getZero(LHS->getType());
3460
3461 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3462 // makes it so that we cannot make much use of NUW.
3463 auto AddFlags = SCEV::FlagAnyWrap;
3464 const bool RHSIsNotMinSigned =
3465 !getSignedRange(RHS).getSignedMin().isMinSignedValue();
3466 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3467 // Let M be the minimum representable signed value. Then (-1)*RHS
3468 // signed-wraps if and only if RHS is M. That can happen even for
3469 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3470 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3471 // (-1)*RHS, we need to prove that RHS != M.
3472 //
3473 // If LHS is non-negative and we know that LHS - RHS does not
3474 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3475 // either by proving that RHS > M or that LHS >= 0.
3476 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
3477 AddFlags = SCEV::FlagNSW;
3478 }
3479 }
3480
3481 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
3482 // RHS is NSW and LHS >= 0.
3483 //
3484 // The difficulty here is that the NSW flag may have been proven
3485 // relative to a loop that is to be found in a recurrence in LHS and
3486 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
3487 // larger scope than intended.
3488 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3489
3490 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags);
3491}
3492
3493/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion of the
3494/// input value to the specified type. If the type must be extended, it is zero
3495/// extended.
3496const SCEV *
3497ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) {
3498 Type *SrcTy = V->getType();
3499 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3501, __PRETTY_FUNCTION__))
3500 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3501, __PRETTY_FUNCTION__))
3501 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3501, __PRETTY_FUNCTION__));
3502 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3503 return V; // No conversion
3504 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3505 return getTruncateExpr(V, Ty);
3506 return getZeroExtendExpr(V, Ty);
3507}
3508
3509/// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion of the
3510/// input value to the specified type. If the type must be extended, it is sign
3511/// extended.
3512const SCEV *
3513ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
3514 Type *Ty) {
3515 Type *SrcTy = V->getType();
3516 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3518, __PRETTY_FUNCTION__))
3517 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3518, __PRETTY_FUNCTION__))
3518 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3518, __PRETTY_FUNCTION__));
3519 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3520 return V; // No conversion
3521 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3522 return getTruncateExpr(V, Ty);
3523 return getSignExtendExpr(V, Ty);
3524}
3525
3526/// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of the
3527/// input value to the specified type. If the type must be extended, it is zero
3528/// extended. The conversion must not be narrowing.
3529const SCEV *
3530ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
3531 Type *SrcTy = V->getType();
3532 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3534, __PRETTY_FUNCTION__))
3533 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3534, __PRETTY_FUNCTION__))
3534 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3534, __PRETTY_FUNCTION__));
3535 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3536, __PRETTY_FUNCTION__))
3536 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3536, __PRETTY_FUNCTION__));
3537 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3538 return V; // No conversion
3539 return getZeroExtendExpr(V, Ty);
3540}
3541
3542/// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of the
3543/// input value to the specified type. If the type must be extended, it is sign
3544/// extended. The conversion must not be narrowing.
3545const SCEV *
3546ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
3547 Type *SrcTy = V->getType();
3548 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3550, __PRETTY_FUNCTION__))
3549 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3550, __PRETTY_FUNCTION__))
3550 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3550, __PRETTY_FUNCTION__));
3551 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3552, __PRETTY_FUNCTION__))
3552 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3552, __PRETTY_FUNCTION__));
3553 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3554 return V; // No conversion
3555 return getSignExtendExpr(V, Ty);
3556}
3557
3558/// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
3559/// the input value to the specified type. If the type must be extended,
3560/// it is extended with unspecified bits. The conversion must not be
3561/// narrowing.
3562const SCEV *
3563ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
3564 Type *SrcTy = V->getType();
3565 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3567, __PRETTY_FUNCTION__))
3566 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3567, __PRETTY_FUNCTION__))
3567 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3567, __PRETTY_FUNCTION__));
3568 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3569, __PRETTY_FUNCTION__))
3569 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3569, __PRETTY_FUNCTION__));
3570 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3571 return V; // No conversion
3572 return getAnyExtendExpr(V, Ty);
3573}
3574
3575/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
3576/// input value to the specified type. The conversion must not be widening.
3577const SCEV *
3578ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
3579 Type *SrcTy = V->getType();
3580 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3582, __PRETTY_FUNCTION__))
3581 (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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3582, __PRETTY_FUNCTION__))
3582 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3582, __PRETTY_FUNCTION__));
3583 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3584, __PRETTY_FUNCTION__))
3584 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3584, __PRETTY_FUNCTION__));
3585 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3586 return V; // No conversion
3587 return getTruncateExpr(V, Ty);
3588}
3589
3590/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
3591/// the types using zero-extension, and then perform a umax operation
3592/// with them.
3593const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
3594 const SCEV *RHS) {
3595 const SCEV *PromotedLHS = LHS;
3596 const SCEV *PromotedRHS = RHS;
3597
3598 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3599 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3600 else
3601 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3602
3603 return getUMaxExpr(PromotedLHS, PromotedRHS);
3604}
3605
3606/// getUMinFromMismatchedTypes - Promote the operands to the wider of
3607/// the types using zero-extension, and then perform a umin operation
3608/// with them.
3609const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3610 const SCEV *RHS) {
3611 const SCEV *PromotedLHS = LHS;
3612 const SCEV *PromotedRHS = RHS;
3613
3614 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3615 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3616 else
3617 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3618
3619 return getUMinExpr(PromotedLHS, PromotedRHS);
3620}
3621
3622/// getPointerBase - Transitively follow the chain of pointer-type operands
3623/// until reaching a SCEV that does not have a single pointer operand. This
3624/// returns a SCEVUnknown pointer for well-formed pointer-type expressions,
3625/// but corner cases do exist.
3626const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
3627 // A pointer operand may evaluate to a nonpointer expression, such as null.
3628 if (!V->getType()->isPointerTy())
3629 return V;
3630
3631 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
3632 return getPointerBase(Cast->getOperand());
3633 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
3634 const SCEV *PtrOp = nullptr;
3635 for (const SCEV *NAryOp : NAry->operands()) {
3636 if (NAryOp->getType()->isPointerTy()) {
3637 // Cannot find the base of an expression with multiple pointer operands.
3638 if (PtrOp)
3639 return V;
3640 PtrOp = NAryOp;
3641 }
3642 }
3643 if (!PtrOp)
3644 return V;
3645 return getPointerBase(PtrOp);
3646 }
3647 return V;
3648}
3649
3650/// PushDefUseChildren - Push users of the given Instruction
3651/// onto the given Worklist.
3652static void
3653PushDefUseChildren(Instruction *I,
3654 SmallVectorImpl<Instruction *> &Worklist) {
3655 // Push the def-use children onto the Worklist stack.
3656 for (User *U : I->users())
3657 Worklist.push_back(cast<Instruction>(U));
3658}
3659
3660/// ForgetSymbolicValue - This looks up computed SCEV values for all
3661/// instructions that depend on the given instruction and removes them from
3662/// the ValueExprMapType map if they reference SymName. This is used during PHI
3663/// resolution.
3664void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
3665 SmallVector<Instruction *, 16> Worklist;
3666 PushDefUseChildren(PN, Worklist);
3667
3668 SmallPtrSet<Instruction *, 8> Visited;
3669 Visited.insert(PN);
3670 while (!Worklist.empty()) {
3671 Instruction *I = Worklist.pop_back_val();
3672 if (!Visited.insert(I).second)
3673 continue;
3674
3675 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
3676 if (It != ValueExprMap.end()) {
3677 const SCEV *Old = It->second;
3678
3679 // Short-circuit the def-use traversal if the symbolic name
3680 // ceases to appear in expressions.
3681 if (Old != SymName && !hasOperand(Old, SymName))
3682 continue;
3683
3684 // SCEVUnknown for a PHI either means that it has an unrecognized
3685 // structure, it's a PHI that's in the progress of being computed
3686 // by createNodeForPHI, or it's a single-value PHI. In the first case,
3687 // additional loop trip count information isn't going to change anything.
3688 // In the second case, createNodeForPHI will perform the necessary
3689 // updates on its own when it gets to that point. In the third, we do
3690 // want to forget the SCEVUnknown.
3691 if (!isa<PHINode>(I) ||
3692 !isa<SCEVUnknown>(Old) ||
3693 (I != PN && Old == SymName)) {
3694 forgetMemoizedResults(Old);
3695 ValueExprMap.erase(It);
3696 }
3697 }
3698
3699 PushDefUseChildren(I, Worklist);
3700 }
3701}
3702
3703namespace {
3704class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
3705public:
3706 static const SCEV *rewrite(const SCEV *S, const Loop *L,
3707 ScalarEvolution &SE) {
3708 SCEVInitRewriter Rewriter(L, SE);
3709 const SCEV *Result = Rewriter.visit(S);
3710 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
3711 }
3712
3713 SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
3714 : SCEVRewriteVisitor(SE), L(L), Valid(true) {}
3715
3716 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
3717 if (!(SE.getLoopDisposition(Expr, L) == ScalarEvolution::LoopInvariant))
3718 Valid = false;
3719 return Expr;
3720 }
3721
3722 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
3723 // Only allow AddRecExprs for this loop.
3724 if (Expr->getLoop() == L)
3725 return Expr->getStart();
3726 Valid = false;
3727 return Expr;
3728 }
3729
3730 bool isValid() { return Valid; }
3731
3732private:
3733 const Loop *L;
3734 bool Valid;
3735};
3736
3737class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
3738public:
3739 static const SCEV *rewrite(const SCEV *S, const Loop *L,
3740 ScalarEvolution &SE) {
3741 SCEVShiftRewriter Rewriter(L, SE);
3742 const SCEV *Result = Rewriter.visit(S);
3743 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
3744 }
3745
3746 SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
3747 : SCEVRewriteVisitor(SE), L(L), Valid(true) {}
3748
3749 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
3750 // Only allow AddRecExprs for this loop.
3751 if (!(SE.getLoopDisposition(Expr, L) == ScalarEvolution::LoopInvariant))
3752 Valid = false;
3753 return Expr;
3754 }
3755
3756 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
3757 if (Expr->getLoop() == L && Expr->isAffine())
3758 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
3759 Valid = false;
3760 return Expr;
3761 }
3762 bool isValid() { return Valid; }
3763
3764private:
3765 const Loop *L;
3766 bool Valid;
3767};
3768} // end anonymous namespace
3769
3770SCEV::NoWrapFlags
3771ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
3772 if (!AR->isAffine())
3773 return SCEV::FlagAnyWrap;
3774
3775 typedef OverflowingBinaryOperator OBO;
3776 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
3777
3778 if (!AR->hasNoSignedWrap()) {
3779 ConstantRange AddRecRange = getSignedRange(AR);
3780 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
3781
3782 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
3783 Instruction::Add, IncRange, OBO::NoSignedWrap);
3784 if (NSWRegion.contains(AddRecRange))
3785 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
3786 }
3787
3788 if (!AR->hasNoUnsignedWrap()) {
3789 ConstantRange AddRecRange = getUnsignedRange(AR);
3790 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
3791
3792 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
3793 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
3794 if (NUWRegion.contains(AddRecRange))
3795 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
3796 }
3797
3798 return Result;
3799}
3800
3801namespace {
3802/// Represents an abstract binary operation. This may exist as a
3803/// normal instruction or constant expression, or may have been
3804/// derived from an expression tree.
3805struct BinaryOp {
3806 unsigned Opcode;
3807 Value *LHS;
3808 Value *RHS;
3809 bool IsNSW;
3810 bool IsNUW;
3811
3812 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
3813 /// constant expression.
3814 Operator *Op;
3815
3816 explicit BinaryOp(Operator *Op)
3817 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
3818 IsNSW(false), IsNUW(false), Op(Op) {
3819 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
3820 IsNSW = OBO->hasNoSignedWrap();
3821 IsNUW = OBO->hasNoUnsignedWrap();
3822 }
3823 }
3824
3825 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
3826 bool IsNUW = false)
3827 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW),
3828 Op(nullptr) {}
3829};
3830}
3831
3832
3833/// Try to map \p V into a BinaryOp, and return \c None on failure.
3834static Optional<BinaryOp> MatchBinaryOp(Value *V) {
3835 auto *Op = dyn_cast<Operator>(V);
3836 if (!Op)
3837 return None;
3838
3839 // Implementation detail: all the cleverness here should happen without
3840 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
3841 // SCEV expressions when possible, and we should not break that.
3842
3843 switch (Op->getOpcode()) {
3844 case Instruction::Add:
3845 case Instruction::Sub:
3846 case Instruction::Mul:
3847 case Instruction::UDiv:
3848 case Instruction::And:
3849 case Instruction::Or:
3850 case Instruction::AShr:
3851 case Instruction::Shl:
3852 return BinaryOp(Op);
3853
3854 case Instruction::Xor:
3855 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
3856 // If the RHS of the xor is a signbit, then this is just an add.
3857 // Instcombine turns add of signbit into xor as a strength reduction step.
3858 if (RHSC->getValue().isSignBit())
3859 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
3860 return BinaryOp(Op);
3861
3862 case Instruction::LShr:
3863 // Turn logical shift right of a constant into a unsigned divide.
3864 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
3865 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
3866
3867 // If the shift count is not less than the bitwidth, the result of
3868 // the shift is undefined. Don't try to analyze it, because the
3869 // resolution chosen here may differ from the resolution chosen in
3870 // other parts of the compiler.
3871 if (SA->getValue().ult(BitWidth)) {
3872 Constant *X =
3873 ConstantInt::get(SA->getContext(),
3874 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
3875 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
3876 }
3877 }
3878 return BinaryOp(Op);
3879
3880 default:
3881 break;
3882 }
3883
3884 return None;
3885}
3886
3887const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
3888 const Loop *L = LI.getLoopFor(PN->getParent());
3889 if (!L || L->getHeader() != PN->getParent())
3890 return nullptr;
3891
3892 // The loop may have multiple entrances or multiple exits; we can analyze
3893 // this phi as an addrec if it has a unique entry value and a unique
3894 // backedge value.
3895 Value *BEValueV = nullptr, *StartValueV = nullptr;
3896 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3897 Value *V = PN->getIncomingValue(i);
3898 if (L->contains(PN->getIncomingBlock(i))) {
3899 if (!BEValueV) {
3900 BEValueV = V;
3901 } else if (BEValueV != V) {
3902 BEValueV = nullptr;
3903 break;
3904 }
3905 } else if (!StartValueV) {
3906 StartValueV = V;
3907 } else if (StartValueV != V) {
3908 StartValueV = nullptr;
3909 break;
3910 }
3911 }
3912 if (BEValueV && StartValueV) {
3913 // While we are analyzing this PHI node, handle its value symbolically.
3914 const SCEV *SymbolicName = getUnknown(PN);
3915 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3916, __PRETTY_FUNCTION__))
3916 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 3916, __PRETTY_FUNCTION__));
3917 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
3918
3919 // Using this symbolic name for the PHI, analyze the value coming around
3920 // the back-edge.
3921 const SCEV *BEValue = getSCEV(BEValueV);
3922
3923 // NOTE: If BEValue is loop invariant, we know that the PHI node just
3924 // has a special value for the first iteration of the loop.
3925
3926 // If the value coming around the backedge is an add with the symbolic
3927 // value we just inserted, then we found a simple induction variable!
3928 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
3929 // If there is a single occurrence of the symbolic value, replace it
3930 // with a recurrence.
3931 unsigned FoundIndex = Add->getNumOperands();
3932 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
3933 if (Add->getOperand(i) == SymbolicName)
3934 if (FoundIndex == e) {
3935 FoundIndex = i;
3936 break;
3937 }
3938
3939 if (FoundIndex != Add->getNumOperands()) {
3940 // Create an add with everything but the specified operand.
3941 SmallVector<const SCEV *, 8> Ops;
3942 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
3943 if (i != FoundIndex)
3944 Ops.push_back(Add->getOperand(i));
3945 const SCEV *Accum = getAddExpr(Ops);
3946
3947 // This is not a valid addrec if the step amount is varying each
3948 // loop iteration, but is not itself an addrec in this loop.
3949 if (isLoopInvariant(Accum, L) ||
3950 (isa<SCEVAddRecExpr>(Accum) &&
3951 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
3952 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
3953
3954 // If the increment doesn't overflow, then neither the addrec nor
3955 // the post-increment will overflow.
3956 if (auto BO = MatchBinaryOp(BEValueV)) {
3957 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
3958 if (BO->IsNUW)
3959 Flags = setFlags(Flags, SCEV::FlagNUW);
3960 if (BO->IsNSW)
3961 Flags = setFlags(Flags, SCEV::FlagNSW);
3962 }
3963 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
3964 // If the increment is an inbounds GEP, then we know the address
3965 // space cannot be wrapped around. We cannot make any guarantee
3966 // about signed or unsigned overflow because pointers are
3967 // unsigned but we may have a negative index from the base
3968 // pointer. We can guarantee that no unsigned wrap occurs if the
3969 // indices form a positive value.
3970 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
3971 Flags = setFlags(Flags, SCEV::FlagNW);
3972
3973 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
3974 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
3975 Flags = setFlags(Flags, SCEV::FlagNUW);
3976 }
3977
3978 // We cannot transfer nuw and nsw flags from subtraction
3979 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
3980 // for instance.
3981 }
3982
3983 const SCEV *StartVal = getSCEV(StartValueV);
3984 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
3985
3986 // Since the no-wrap flags are on the increment, they apply to the
3987 // post-incremented value as well.
3988 if (isLoopInvariant(Accum, L))
3989 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
3990
3991 // Okay, for the entire analysis of this edge we assumed the PHI
3992 // to be symbolic. We now need to go back and purge all of the
3993 // entries for the scalars that use the symbolic expression.
3994 forgetSymbolicName(PN, SymbolicName);
3995 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
3996 return PHISCEV;
3997 }
3998 }
3999 } else {
4000 // Otherwise, this could be a loop like this:
4001 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
4002 // In this case, j = {1,+,1} and BEValue is j.
4003 // Because the other in-value of i (0) fits the evolution of BEValue
4004 // i really is an addrec evolution.
4005 //
4006 // We can generalize this saying that i is the shifted value of BEValue
4007 // by one iteration:
4008 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
4009 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
4010 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this);
4011 if (Shifted != getCouldNotCompute() &&
4012 Start != getCouldNotCompute()) {
4013 const SCEV *StartVal = getSCEV(StartValueV);
4014 if (Start == StartVal) {
4015 // Okay, for the entire analysis of this edge we assumed the PHI
4016 // to be symbolic. We now need to go back and purge all of the
4017 // entries for the scalars that use the symbolic expression.
4018 forgetSymbolicName(PN, SymbolicName);
4019 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
4020 return Shifted;
4021 }
4022 }
4023 }
4024
4025 // Remove the temporary PHI node SCEV that has been inserted while intending
4026 // to create an AddRecExpr for this PHI node. We can not keep this temporary
4027 // as it will prevent later (possibly simpler) SCEV expressions to be added
4028 // to the ValueExprMap.
4029 ValueExprMap.erase(PN);
4030 }
4031
4032 return nullptr;
4033}
4034
4035// Checks if the SCEV S is available at BB. S is considered available at BB
4036// if S can be materialized at BB without introducing a fault.
4037static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
4038 BasicBlock *BB) {
4039 struct CheckAvailable {
4040 bool TraversalDone = false;
4041 bool Available = true;
4042
4043 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
4044 BasicBlock *BB = nullptr;
4045 DominatorTree &DT;
4046
4047 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
4048 : L(L), BB(BB), DT(DT) {}
4049
4050 bool setUnavailable() {
4051 TraversalDone = true;
4052 Available = false;
4053 return false;
4054 }
4055
4056 bool follow(const SCEV *S) {
4057 switch (S->getSCEVType()) {
4058 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
4059 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
4060 // These expressions are available if their operand(s) is/are.
4061 return true;
4062
4063 case scAddRecExpr: {
4064 // We allow add recurrences that are on the loop BB is in, or some
4065 // outer loop. This guarantees availability because the value of the
4066 // add recurrence at BB is simply the "current" value of the induction
4067 // variable. We can relax this in the future; for instance an add
4068 // recurrence on a sibling dominating loop is also available at BB.
4069 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
4070 if (L && (ARLoop == L || ARLoop->contains(L)))
4071 return true;
4072
4073 return setUnavailable();
4074 }
4075
4076 case scUnknown: {
4077 // For SCEVUnknown, we check for simple dominance.
4078 const auto *SU = cast<SCEVUnknown>(S);
4079 Value *V = SU->getValue();
4080
4081 if (isa<Argument>(V))
4082 return false;
4083
4084 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
4085 return false;
4086
4087 return setUnavailable();
4088 }
4089
4090 case scUDivExpr:
4091 case scCouldNotCompute:
4092 // We do not try to smart about these at all.
4093 return setUnavailable();
4094 }
4095 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4095);
4096 }
4097
4098 bool isDone() { return TraversalDone; }
4099 };
4100
4101 CheckAvailable CA(L, BB, DT);
4102 SCEVTraversal<CheckAvailable> ST(CA);
4103
4104 ST.visitAll(S);
4105 return CA.Available;
4106}
4107
4108// Try to match a control flow sequence that branches out at BI and merges back
4109// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
4110// match.
4111static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
4112 Value *&C, Value *&LHS, Value *&RHS) {
4113 C = BI->getCondition();
4114
4115 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
4116 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
4117
4118 if (!LeftEdge.isSingleEdge())
4119 return false;
4120
4121 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4121, __PRETTY_FUNCTION__));
4122
4123 Use &LeftUse = Merge->getOperandUse(0);
4124 Use &RightUse = Merge->getOperandUse(1);
4125
4126 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
4127 LHS = LeftUse;
4128 RHS = RightUse;
4129 return true;
4130 }
4131
4132 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
4133 LHS = RightUse;
4134 RHS = LeftUse;
4135 return true;
4136 }
4137
4138 return false;
4139}
4140
4141const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
4142 if (PN->getNumIncomingValues() == 2) {
4143 const Loop *L = LI.getLoopFor(PN->getParent());
4144
4145 // We don't want to break LCSSA, even in a SCEV expression tree.
4146 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
4147 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
4148 return nullptr;
4149
4150 // Try to match
4151 //
4152 // br %cond, label %left, label %right
4153 // left:
4154 // br label %merge
4155 // right:
4156 // br label %merge
4157 // merge:
4158 // V = phi [ %x, %left ], [ %y, %right ]
4159 //
4160 // as "select %cond, %x, %y"
4161
4162 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
4163 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4163, __PRETTY_FUNCTION__));
4164
4165 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
4166 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
4167
4168 if (BI && BI->isConditional() &&
4169 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
4170 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
4171 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
4172 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
4173 }
4174
4175 return nullptr;
4176}
4177
4178const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
4179 if (const SCEV *S = createAddRecFromPHI(PN))
4180 return S;
4181
4182 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
4183 return S;
4184
4185 // If the PHI has a single incoming value, follow that value, unless the
4186 // PHI's incoming blocks are in a different loop, in which case doing so
4187 // risks breaking LCSSA form. Instcombine would normally zap these, but
4188 // it doesn't have DominatorTree information, so it may miss cases.
4189 if (Value *V = SimplifyInstruction(PN, getDataLayout(), &TLI, &DT, &AC))
4190 if (LI.replacementPreservesLCSSAForm(PN, V))
4191 return getSCEV(V);
4192
4193 // If it's not a loop phi, we can't handle it yet.
4194 return getUnknown(PN);
4195}
4196
4197const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
4198 Value *Cond,
4199 Value *TrueVal,
4200 Value *FalseVal) {
4201 // Handle "constant" branch or select. This can occur for instance when a
4202 // loop pass transforms an inner loop and moves on to process the outer loop.
4203 if (auto *CI = dyn_cast<ConstantInt>(Cond))
4204 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
4205
4206 // Try to match some simple smax or umax patterns.
4207 auto *ICI = dyn_cast<ICmpInst>(Cond);
4208 if (!ICI)
4209 return getUnknown(I);
4210
4211 Value *LHS = ICI->getOperand(0);
4212 Value *RHS = ICI->getOperand(1);
4213
4214 switch (ICI->getPredicate()) {
4215 case ICmpInst::ICMP_SLT:
4216 case ICmpInst::ICMP_SLE:
4217 std::swap(LHS, RHS);
4218 // fall through
4219 case ICmpInst::ICMP_SGT:
4220 case ICmpInst::ICMP_SGE:
4221 // a >s b ? a+x : b+x -> smax(a, b)+x
4222 // a >s b ? b+x : a+x -> smin(a, b)+x
4223 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
4224 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
4225 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
4226 const SCEV *LA = getSCEV(TrueVal);
4227 const SCEV *RA = getSCEV(FalseVal);
4228 const SCEV *LDiff = getMinusSCEV(LA, LS);
4229 const SCEV *RDiff = getMinusSCEV(RA, RS);
4230 if (LDiff == RDiff)
4231 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
4232 LDiff = getMinusSCEV(LA, RS);
4233 RDiff = getMinusSCEV(RA, LS);
4234 if (LDiff == RDiff)
4235 return getAddExpr(getSMinExpr(LS, RS), LDiff);
4236 }
4237 break;
4238 case ICmpInst::ICMP_ULT:
4239 case ICmpInst::ICMP_ULE:
4240 std::swap(LHS, RHS);
4241 // fall through
4242 case ICmpInst::ICMP_UGT:
4243 case ICmpInst::ICMP_UGE:
4244 // a >u b ? a+x : b+x -> umax(a, b)+x
4245 // a >u b ? b+x : a+x -> umin(a, b)+x
4246 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
4247 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4248 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
4249 const SCEV *LA = getSCEV(TrueVal);
4250 const SCEV *RA = getSCEV(FalseVal);
4251 const SCEV *LDiff = getMinusSCEV(LA, LS);
4252 const SCEV *RDiff = getMinusSCEV(RA, RS);
4253 if (LDiff == RDiff)
4254 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
4255 LDiff = getMinusSCEV(LA, RS);
4256 RDiff = getMinusSCEV(RA, LS);
4257 if (LDiff == RDiff)
4258 return getAddExpr(getUMinExpr(LS, RS), LDiff);
4259 }
4260 break;
4261 case ICmpInst::ICMP_NE:
4262 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
4263 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
4264 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
4265 const SCEV *One = getOne(I->getType());
4266 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4267 const SCEV *LA = getSCEV(TrueVal);
4268 const SCEV *RA = getSCEV(FalseVal);
4269 const SCEV *LDiff = getMinusSCEV(LA, LS);
4270 const SCEV *RDiff = getMinusSCEV(RA, One);
4271 if (LDiff == RDiff)
4272 return getAddExpr(getUMaxExpr(One, LS), LDiff);
4273 }
4274 break;
4275 case ICmpInst::ICMP_EQ:
4276 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
4277 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
4278 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
4279 const SCEV *One = getOne(I->getType());
4280 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4281 const SCEV *LA = getSCEV(TrueVal);
4282 const SCEV *RA = getSCEV(FalseVal);
4283 const SCEV *LDiff = getMinusSCEV(LA, One);
4284 const SCEV *RDiff = getMinusSCEV(RA, LS);
4285 if (LDiff == RDiff)
4286 return getAddExpr(getUMaxExpr(One, LS), LDiff);
4287 }
4288 break;
4289 default:
4290 break;
4291 }
4292
4293 return getUnknown(I);
4294}
4295
4296/// createNodeForGEP - Expand GEP instructions into add and multiply
4297/// operations. This allows them to be analyzed by regular SCEV code.
4298///
4299const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
4300 // Don't attempt to analyze GEPs over unsized objects.
4301 if (!GEP->getSourceElementType()->isSized())
4302 return getUnknown(GEP);
4303
4304 SmallVector<const SCEV *, 4> IndexExprs;
4305 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
4306 IndexExprs.push_back(getSCEV(*Index));
4307 return getGEPExpr(GEP->getSourceElementType(),
4308 getSCEV(GEP->getPointerOperand()),
4309 IndexExprs, GEP->isInBounds());
4310}
4311
4312/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
4313/// guaranteed to end in (at every loop iteration). It is, at the same time,
4314/// the minimum number of times S is divisible by 2. For example, given {4,+,8}
4315/// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S.
4316uint32_t
4317ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
4318 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
4319 return C->getAPInt().countTrailingZeros();
4320
4321 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
4322 return std::min(GetMinTrailingZeros(T->getOperand()),
4323 (uint32_t)getTypeSizeInBits(T->getType()));
4324
4325 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
4326 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
4327 return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
4328 getTypeSizeInBits(E->getType()) : OpRes;
4329 }
4330
4331 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
4332 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
4333 return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
4334 getTypeSizeInBits(E->getType()) : OpRes;
4335 }
4336
4337 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
4338 // The result is the min of all operands results.
4339 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
4340 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
4341 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
4342 return MinOpRes;
4343 }
4344
4345 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
4346 // The result is the sum of all operands results.
4347 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
4348 uint32_t BitWidth = getTypeSizeInBits(M->getType());
4349 for (unsigned i = 1, e = M->getNumOperands();
4350 SumOpRes != BitWidth && i != e; ++i)
4351 SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)),
4352 BitWidth);
4353 return SumOpRes;
4354 }
4355
4356 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
4357 // The result is the min of all operands results.
4358 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
4359 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
4360 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
4361 return MinOpRes;
4362 }
4363
4364 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
4365 // The result is the min of all operands results.
4366 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
4367 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
4368 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
4369 return MinOpRes;
4370 }
4371
4372 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
4373 // The result is the min of all operands results.
4374 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
4375 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
4376 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
4377 return MinOpRes;
4378 }
4379
4380 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
4381 // For a SCEVUnknown, ask ValueTracking.
4382 unsigned BitWidth = getTypeSizeInBits(U->getType());
4383 APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
4384 computeKnownBits(U->getValue(), Zeros, Ones, getDataLayout(), 0, &AC,
4385 nullptr, &DT);
4386 return Zeros.countTrailingOnes();
4387 }
4388
4389 // SCEVUDivExpr
4390 return 0;
4391}
4392
4393/// GetRangeFromMetadata - Helper method to assign a range to V from
4394/// metadata present in the IR.
4395static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
4396 if (Instruction *I = dyn_cast<Instruction>(V))
4397 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
4398 return getConstantRangeFromMetadata(*MD);
4399
4400 return None;
4401}
4402
4403/// getRange - Determine the range for a particular SCEV. If SignHint is
4404/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
4405/// with a "cleaner" unsigned (resp. signed) representation.
4406///
4407ConstantRange
4408ScalarEvolution::getRange(const SCEV *S,
4409 ScalarEvolution::RangeSignHint SignHint) {
4410 DenseMap<const SCEV *, ConstantRange> &Cache =
4411 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
4412 : SignedRanges;
4413
4414 // See if we've computed this range already.
4415 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
4416 if (I != Cache.end())
4417 return I->second;
4418
4419 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
4420 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
4421
4422 unsigned BitWidth = getTypeSizeInBits(S->getType());
4423 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
4424
4425 // If the value has known zeros, the maximum value will have those known zeros
4426 // as well.
4427 uint32_t TZ = GetMinTrailingZeros(S);
4428 if (TZ != 0) {
4429 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
4430 ConservativeResult =
4431 ConstantRange(APInt::getMinValue(BitWidth),
4432 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
4433 else
4434 ConservativeResult = ConstantRange(
4435 APInt::getSignedMinValue(BitWidth),
4436 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
4437 }
4438
4439 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
4440 ConstantRange X = getRange(Add->getOperand(0), SignHint);
4441 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
4442 X = X.add(getRange(Add->getOperand(i), SignHint));
4443 return setRange(Add, SignHint, ConservativeResult.intersectWith(X));
4444 }
4445
4446 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
4447 ConstantRange X = getRange(Mul->getOperand(0), SignHint);
4448 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
4449 X = X.multiply(getRange(Mul->getOperand(i), SignHint));
4450 return setRange(Mul, SignHint, ConservativeResult.intersectWith(X));
4451 }
4452
4453 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
4454 ConstantRange X = getRange(SMax->getOperand(0), SignHint);
4455 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
4456 X = X.smax(getRange(SMax->getOperand(i), SignHint));
4457 return setRange(SMax, SignHint, ConservativeResult.intersectWith(X));
4458 }
4459
4460 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
4461 ConstantRange X = getRange(UMax->getOperand(0), SignHint);
4462 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
4463 X = X.umax(getRange(UMax->getOperand(i), SignHint));
4464 return setRange(UMax, SignHint, ConservativeResult.intersectWith(X));
4465 }
4466
4467 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
4468 ConstantRange X = getRange(UDiv->getLHS(), SignHint);
4469 ConstantRange Y = getRange(UDiv->getRHS(), SignHint);
4470 return setRange(UDiv, SignHint,
4471 ConservativeResult.intersectWith(X.udiv(Y)));
4472 }
4473
4474 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
4475 ConstantRange X = getRange(ZExt->getOperand(), SignHint);
4476 return setRange(ZExt, SignHint,
4477 ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
4478 }
4479
4480 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
4481 ConstantRange X = getRange(SExt->getOperand(), SignHint);
4482 return setRange(SExt, SignHint,
4483 ConservativeResult.intersectWith(X.signExtend(BitWidth)));
4484 }
4485
4486 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
4487 ConstantRange X = getRange(Trunc->getOperand(), SignHint);
4488 return setRange(Trunc, SignHint,
4489 ConservativeResult.intersectWith(X.truncate(BitWidth)));
4490 }
4491
4492 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
4493 // If there's no unsigned wrap, the value will never be less than its
4494 // initial value.
4495 if (AddRec->hasNoUnsignedWrap())
4496 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
4497 if (!C->getValue()->isZero())
4498 ConservativeResult = ConservativeResult.intersectWith(
4499 ConstantRange(C->getAPInt(), APInt(BitWidth, 0)));
4500
4501 // If there's no signed wrap, and all the operands have the same sign or
4502 // zero, the value won't ever change sign.
4503 if (AddRec->hasNoSignedWrap()) {
4504 bool AllNonNeg = true;
4505 bool AllNonPos = true;
4506 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
4507 if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
4508 if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
4509 }
4510 if (AllNonNeg)
4511 ConservativeResult = ConservativeResult.intersectWith(
4512 ConstantRange(APInt(BitWidth, 0),
4513 APInt::getSignedMinValue(BitWidth)));
4514 else if (AllNonPos)
4515 ConservativeResult = ConservativeResult.intersectWith(
4516 ConstantRange(APInt::getSignedMinValue(BitWidth),
4517 APInt(BitWidth, 1)));
4518 }
4519
4520 // TODO: non-affine addrec
4521 if (AddRec->isAffine()) {
4522 const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
4523 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
4524 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
4525 auto RangeFromAffine = getRangeForAffineAR(
4526 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
4527 BitWidth);
4528 if (!RangeFromAffine.isFullSet())
4529 ConservativeResult =
4530 ConservativeResult.intersectWith(RangeFromAffine);
4531
4532 auto RangeFromFactoring = getRangeViaFactoring(
4533 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
4534 BitWidth);
4535 if (!RangeFromFactoring.isFullSet())
4536 ConservativeResult =
4537 ConservativeResult.intersectWith(RangeFromFactoring);
4538 }
4539 }
4540
4541 return setRange(AddRec, SignHint, ConservativeResult);
4542 }
4543
4544 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
4545 // Check if the IR explicitly contains !range metadata.
4546 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
4547 if (MDRange.hasValue())
4548 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue());
4549
4550 // Split here to avoid paying the compile-time cost of calling both
4551 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
4552 // if needed.
4553 const DataLayout &DL = getDataLayout();
4554 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
4555 // For a SCEVUnknown, ask ValueTracking.
4556 APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
4557 computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, &AC, nullptr, &DT);
4558 if (Ones != ~Zeros + 1)
4559 ConservativeResult =
4560 ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1));
4561 } else {
4562 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4563, __PRETTY_FUNCTION__))
4563 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4563, __PRETTY_FUNCTION__));
4564 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
4565 if (NS > 1)
4566 ConservativeResult = ConservativeResult.intersectWith(
4567 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
4568 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1));
4569 }
4570
4571 return setRange(U, SignHint, ConservativeResult);
4572 }
4573
4574 return setRange(S, SignHint, ConservativeResult);
4575}
4576
4577ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
4578 const SCEV *Step,
4579 const SCEV *MaxBECount,
4580 unsigned BitWidth) {
4581 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4583, __PRETTY_FUNCTION__))
4582 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4583, __PRETTY_FUNCTION__))
4583 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4583, __PRETTY_FUNCTION__));
4584
4585 ConstantRange Result(BitWidth, /* isFullSet = */ true);
4586
4587 // Check for overflow. This must be done with ConstantRange arithmetic
4588 // because we could be called from within the ScalarEvolution overflow
4589 // checking code.
4590
4591 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
4592 ConstantRange MaxBECountRange = getUnsignedRange(MaxBECount);
4593 ConstantRange ZExtMaxBECountRange =
4594 MaxBECountRange.zextOrTrunc(BitWidth * 2 + 1);
4595
4596 ConstantRange StepSRange = getSignedRange(Step);
4597 ConstantRange SExtStepSRange = StepSRange.sextOrTrunc(BitWidth * 2 + 1);
4598
4599 ConstantRange StartURange = getUnsignedRange(Start);
4600 ConstantRange EndURange =
4601 StartURange.add(MaxBECountRange.multiply(StepSRange));
4602
4603 // Check for unsigned overflow.
4604 ConstantRange ZExtStartURange = StartURange.zextOrTrunc(BitWidth * 2 + 1);
4605 ConstantRange ZExtEndURange = EndURange.zextOrTrunc(BitWidth * 2 + 1);
4606 if (ZExtStartURange.add(ZExtMaxBECountRange.multiply(SExtStepSRange)) ==
4607 ZExtEndURange) {
4608 APInt Min = APIntOps::umin(StartURange.getUnsignedMin(),
4609 EndURange.getUnsignedMin());
4610 APInt Max = APIntOps::umax(StartURange.getUnsignedMax(),
4611 EndURange.getUnsignedMax());
4612 bool IsFullRange = Min.isMinValue() && Max.isMaxValue();
4613 if (!IsFullRange)
4614 Result =
4615 Result.intersectWith(ConstantRange(Min, Max + 1));
4616 }
4617
4618 ConstantRange StartSRange = getSignedRange(Start);
4619 ConstantRange EndSRange =
4620 StartSRange.add(MaxBECountRange.multiply(StepSRange));
4621
4622 // Check for signed overflow. This must be done with ConstantRange
4623 // arithmetic because we could be called from within the ScalarEvolution
4624 // overflow checking code.
4625 ConstantRange SExtStartSRange = StartSRange.sextOrTrunc(BitWidth * 2 + 1);
4626 ConstantRange SExtEndSRange = EndSRange.sextOrTrunc(BitWidth * 2 + 1);
4627 if (SExtStartSRange.add(ZExtMaxBECountRange.multiply(SExtStepSRange)) ==
4628 SExtEndSRange) {
4629 APInt Min =
4630 APIntOps::smin(StartSRange.getSignedMin(), EndSRange.getSignedMin());
4631 APInt Max =
4632 APIntOps::smax(StartSRange.getSignedMax(), EndSRange.getSignedMax());
4633 bool IsFullRange = Min.isMinSignedValue() && Max.isMaxSignedValue();
4634 if (!IsFullRange)
4635 Result =
4636 Result.intersectWith(ConstantRange(Min, Max + 1));
4637 }
4638
4639 return Result;
4640}
4641
4642ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
4643 const SCEV *Step,
4644 const SCEV *MaxBECount,
4645 unsigned BitWidth) {
4646 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
4647 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
4648
4649 struct SelectPattern {
4650 Value *Condition = nullptr;
4651 APInt TrueValue;
4652 APInt FalseValue;
4653
4654 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
4655 const SCEV *S) {
4656 Optional<unsigned> CastOp;
4657 APInt Offset(BitWidth, 0);
4658
4659 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4660, __PRETTY_FUNCTION__))
4660 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4660, __PRETTY_FUNCTION__));
4661
4662 // Peel off a constant offset:
4663 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
4664 // In the future we could consider being smarter here and handle
4665 // {Start+Step,+,Step} too.
4666 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
4667 return;
4668
4669 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
4670 S = SA->getOperand(1);
4671 }
4672
4673 // Peel off a cast operation
4674 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
4675 CastOp = SCast->getSCEVType();
4676 S = SCast->getOperand();
4677 }
4678
4679 using namespace llvm::PatternMatch;
4680
4681 auto *SU = dyn_cast<SCEVUnknown>(S);
4682 const APInt *TrueVal, *FalseVal;
4683 if (!SU ||
4684 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
4685 m_APInt(FalseVal)))) {
4686 Condition = nullptr;
4687 return;
4688 }
4689
4690 TrueValue = *TrueVal;
4691 FalseValue = *FalseVal;
4692
4693 // Re-apply the cast we peeled off earlier
4694 if (CastOp.hasValue())
4695 switch (*CastOp) {
4696 default:
4697 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 4697);
4698
4699 case scTruncate:
4700 TrueValue = TrueValue.trunc(BitWidth);
4701 FalseValue = FalseValue.trunc(BitWidth);
4702 break;
4703 case scZeroExtend:
4704 TrueValue = TrueValue.zext(BitWidth);
4705 FalseValue = FalseValue.zext(BitWidth);
4706 break;
4707 case scSignExtend:
4708 TrueValue = TrueValue.sext(BitWidth);
4709 FalseValue = FalseValue.sext(BitWidth);
4710 break;
4711 }
4712
4713 // Re-apply the constant offset we peeled off earlier
4714 TrueValue += Offset;
4715 FalseValue += Offset;
4716 }
4717
4718 bool isRecognized() { return Condition != nullptr; }
4719 };
4720
4721 SelectPattern StartPattern(*this, BitWidth, Start);
4722 if (!StartPattern.isRecognized())
4723 return ConstantRange(BitWidth, /* isFullSet = */ true);
4724
4725 SelectPattern StepPattern(*this, BitWidth, Step);
4726 if (!StepPattern.isRecognized())
4727 return ConstantRange(BitWidth, /* isFullSet = */ true);
4728
4729 if (StartPattern.Condition != StepPattern.Condition) {
4730 // We don't handle this case today; but we could, by considering four
4731 // possibilities below instead of two. I'm not sure if there are cases where
4732 // that will help over what getRange already does, though.
4733 return ConstantRange(BitWidth, /* isFullSet = */ true);
4734 }
4735
4736 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
4737 // construct arbitrary general SCEV expressions here. This function is called
4738 // from deep in the call stack, and calling getSCEV (on a sext instruction,
4739 // say) can end up caching a suboptimal value.
4740
4741 // FIXME: without the explicit `this` receiver below, MSVC errors out with
4742 // C2352 and C2512 (otherwise it isn't needed).
4743
4744 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
4745 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
4746 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
4747 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
4748
4749 ConstantRange TrueRange =
4750 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
4751 ConstantRange FalseRange =
4752 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
4753
4754 return TrueRange.unionWith(FalseRange);
4755}
4756
4757SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
4758 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
4759 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
4760
4761 // Return early if there are no flags to propagate to the SCEV.
4762 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4763 if (BinOp->hasNoUnsignedWrap())
4764 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
4765 if (BinOp->hasNoSignedWrap())
4766 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
4767 if (Flags == SCEV::FlagAnyWrap)
4768 return SCEV::FlagAnyWrap;
4769
4770 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
4771}
4772
4773bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
4774 // Here we check that I is in the header of the innermost loop containing I,
4775 // since we only deal with instructions in the loop header. The actual loop we
4776 // need to check later will come from an add recurrence, but getting that
4777 // requires computing the SCEV of the operands, which can be expensive. This
4778 // check we can do cheaply to rule out some cases early.
4779 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
4780 if (InnermostContainingLoop == nullptr ||
4781 InnermostContainingLoop->getHeader() != I->getParent())
4782 return false;
4783
4784 // Only proceed if we can prove that I does not yield poison.
4785 if (!isKnownNotFullPoison(I)) return false;
4786
4787 // At this point we know that if I is executed, then it does not wrap
4788 // according to at least one of NSW or NUW. If I is not executed, then we do
4789 // not know if the calculation that I represents would wrap. Multiple
4790 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
4791 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
4792 // derived from other instructions that map to the same SCEV. We cannot make
4793 // that guarantee for cases where I is not executed. So we need to find the
4794 // loop that I is considered in relation to and prove that I is executed for
4795 // every iteration of that loop. That implies that the value that I
4796 // calculates does not wrap anywhere in the loop, so then we can apply the
4797 // flags to the SCEV.
4798 //
4799 // We check isLoopInvariant to disambiguate in case we are adding recurrences
4800 // from different loops, so that we know which loop to prove that I is
4801 // executed in.
4802 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
4803 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
4804 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
4805 bool AllOtherOpsLoopInvariant = true;
4806 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
4807 ++OtherOpIndex) {
4808 if (OtherOpIndex != OpIndex) {
4809 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
4810 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
4811 AllOtherOpsLoopInvariant = false;
4812 break;
4813 }
4814 }
4815 }
4816 if (AllOtherOpsLoopInvariant &&
4817 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
4818 return true;
4819 }
4820 }
4821 return false;
4822}
4823
4824/// createSCEV - We know that there is no SCEV for the specified value. Analyze
4825/// the expression.
4826///
4827const SCEV *ScalarEvolution::createSCEV(Value *V) {
4828 if (!isSCEVable(V->getType()))
4829 return getUnknown(V);
4830
4831 if (Instruction *I = dyn_cast<Instruction>(V)) {
4832 // Don't attempt to analyze instructions in blocks that aren't
4833 // reachable. Such instructions don't matter, and they aren't required
4834 // to obey basic rules for definitions dominating uses which this
4835 // analysis depends on.
4836 if (!DT.isReachableFromEntry(I->getParent()))
4837 return getUnknown(V);
4838 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
4839 return getConstant(CI);
4840 else if (isa<ConstantPointerNull>(V))
4841 return getZero(V->getType());
4842 else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
4843 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
4844 else if (!isa<ConstantExpr>(V))
4845 return getUnknown(V);
4846
4847 Operator *U = cast<Operator>(V);
4848 if (auto BO = MatchBinaryOp(U)) {
4849 switch (BO->Opcode) {
4850 case Instruction::Add: {
4851 // The simple thing to do would be to just call getSCEV on both operands
4852 // and call getAddExpr with the result. However if we're looking at a
4853 // bunch of things all added together, this can be quite inefficient,
4854 // because it leads to N-1 getAddExpr calls for N ultimate operands.
4855 // Instead, gather up all the operands and make a single getAddExpr call.
4856 // LLVM IR canonical form means we need only traverse the left operands.
4857 SmallVector<const SCEV *, 4> AddOps;
4858 do {
4859 if (BO->Op) {
4860 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
4861 AddOps.push_back(OpSCEV);
4862 break;
4863 }
4864
4865 // If a NUW or NSW flag can be applied to the SCEV for this
4866 // addition, then compute the SCEV for this addition by itself
4867 // with a separate call to getAddExpr. We need to do that
4868 // instead of pushing the operands of the addition onto AddOps,
4869 // since the flags are only known to apply to this particular
4870 // addition - they may not apply to other additions that can be
4871 // formed with operands from AddOps.
4872 const SCEV *RHS = getSCEV(BO->RHS);
4873 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
4874 if (Flags != SCEV::FlagAnyWrap) {
4875 const SCEV *LHS = getSCEV(BO->LHS);
4876 if (BO->Opcode == Instruction::Sub)
4877 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
4878 else
4879 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
4880 break;
4881 }
4882 }
4883
4884 if (BO->Opcode == Instruction::Sub)
4885 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
4886 else
4887 AddOps.push_back(getSCEV(BO->RHS));
4888
4889 auto NewBO = MatchBinaryOp(BO->LHS);
4890 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
4891 NewBO->Opcode != Instruction::Sub)) {
4892 AddOps.push_back(getSCEV(BO->LHS));
4893 break;
4894 }
4895 BO = NewBO;
4896 } while (true);
4897
4898 return getAddExpr(AddOps);
4899 }
4900
4901 case Instruction::Mul: {
4902 SmallVector<const SCEV *, 4> MulOps;
4903 do {
4904 if (BO->Op) {
4905 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
4906 MulOps.push_back(OpSCEV);
4907 break;
4908 }
4909
4910 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
4911 if (Flags != SCEV::FlagAnyWrap) {
4912 MulOps.push_back(
4913 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
4914 break;
4915 }
4916 }
4917
4918 MulOps.push_back(getSCEV(BO->RHS));
4919 auto NewBO = MatchBinaryOp(BO->LHS);
4920 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
4921 MulOps.push_back(getSCEV(BO->LHS));
4922 break;
4923 }
4924 BO = NewBO;
4925 } while (true);
4926
4927 return getMulExpr(MulOps);
4928 }
4929 case Instruction::UDiv:
4930 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
4931 case Instruction::Sub: {
4932 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4933 if (BO->Op)
4934 Flags = getNoWrapFlagsFromUB(BO->Op);
4935 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
4936 }
4937 case Instruction::And:
4938 // For an expression like x&255 that merely masks off the high bits,
4939 // use zext(trunc(x)) as the SCEV expression.
4940 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
4941 if (CI->isNullValue())
4942 return getSCEV(BO->RHS);
4943 if (CI->isAllOnesValue())
4944 return getSCEV(BO->LHS);
4945 const APInt &A = CI->getValue();
4946
4947 // Instcombine's ShrinkDemandedConstant may strip bits out of
4948 // constants, obscuring what would otherwise be a low-bits mask.
4949 // Use computeKnownBits to compute what ShrinkDemandedConstant
4950 // knew about to reconstruct a low-bits mask value.
4951 unsigned LZ = A.countLeadingZeros();
4952 unsigned TZ = A.countTrailingZeros();
4953 unsigned BitWidth = A.getBitWidth();
4954 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
4955 computeKnownBits(BO->LHS, KnownZero, KnownOne, getDataLayout(),
4956 0, &AC, nullptr, &DT);
4957
4958 APInt EffectiveMask =
4959 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
4960 if ((LZ != 0 || TZ != 0) && !((~A & ~KnownZero) & EffectiveMask)) {
4961 const SCEV *MulCount = getConstant(ConstantInt::get(
4962 getContext(), APInt::getOneBitSet(BitWidth, TZ)));
4963 return getMulExpr(
4964 getZeroExtendExpr(
4965 getTruncateExpr(
4966 getUDivExactExpr(getSCEV(BO->LHS), MulCount),
4967 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
4968 BO->LHS->getType()),
4969 MulCount);
4970 }
4971 }
4972 break;
4973
4974 case Instruction::Or:
4975 // If the RHS of the Or is a constant, we may have something like:
4976 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
4977 // optimizations will transparently handle this case.
4978 //
4979 // In order for this transformation to be safe, the LHS must be of the
4980 // form X*(2^n) and the Or constant must be less than 2^n.
4981 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
4982 const SCEV *LHS = getSCEV(BO->LHS);
4983 const APInt &CIVal = CI->getValue();
4984 if (GetMinTrailingZeros(LHS) >=
4985 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
4986 // Build a plain add SCEV.
4987 const SCEV *S = getAddExpr(LHS, getSCEV(CI));
4988 // If the LHS of the add was an addrec and it has no-wrap flags,
4989 // transfer the no-wrap flags, since an or won't introduce a wrap.
4990 if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
4991 const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
4992 const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
4993 OldAR->getNoWrapFlags());
4994 }
4995 return S;
4996 }
4997 }
4998 break;
4999
5000 case Instruction::Xor:
5001 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5002 // If the RHS of xor is -1, then this is a not operation.
5003 if (CI->isAllOnesValue())
5004 return getNotSCEV(getSCEV(BO->LHS));
5005
5006 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
5007 // This is a variant of the check for xor with -1, and it handles
5008 // the case where instcombine has trimmed non-demanded bits out
5009 // of an xor with -1.
5010 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
5011 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
5012 if (LBO->getOpcode() == Instruction::And &&
5013 LCI->getValue() == CI->getValue())
5014 if (const SCEVZeroExtendExpr *Z =
5015 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
5016 Type *UTy = BO->LHS->getType();
5017 const SCEV *Z0 = Z->getOperand();
5018 Type *Z0Ty = Z0->getType();
5019 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
5020
5021 // If C is a low-bits mask, the zero extend is serving to
5022 // mask off the high bits. Complement the operand and
5023 // re-apply the zext.
5024 if (APIntOps::isMask(Z0TySize, CI->getValue()))
5025 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
5026
5027 // If C is a single bit, it may be in the sign-bit position
5028 // before the zero-extend. In this case, represent the xor
5029 // using an add, which is equivalent, and re-apply the zext.
5030 APInt Trunc = CI->getValue().trunc(Z0TySize);
5031 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
5032 Trunc.isSignBit())
5033 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
5034 UTy);
5035 }
5036 }
5037 break;
5038
5039 case Instruction::Shl:
5040 // Turn shift left of a constant amount into a multiply.
5041 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
5042 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
5043
5044 // If the shift count is not less than the bitwidth, the result of
5045 // the shift is undefined. Don't try to analyze it, because the
5046 // resolution chosen here may differ from the resolution chosen in
5047 // other parts of the compiler.
5048 if (SA->getValue().uge(BitWidth))
5049 break;
5050
5051 // It is currently not resolved how to interpret NSW for left
5052 // shift by BitWidth - 1, so we avoid applying flags in that
5053 // case. Remove this check (or this comment) once the situation
5054 // is resolved. See
5055 // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html
5056 // and http://reviews.llvm.org/D8890 .
5057 auto Flags = SCEV::FlagAnyWrap;
5058 if (BO->Op && SA->getValue().ult(BitWidth - 1))
5059 Flags = getNoWrapFlagsFromUB(BO->Op);
5060
5061 Constant *X = ConstantInt::get(getContext(),
5062 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
5063 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
5064 }
5065 break;
5066
5067 case Instruction::AShr:
5068 // For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression.
5069 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS))
5070 if (Operator *L = dyn_cast<Operator>(BO->LHS))
5071 if (L->getOpcode() == Instruction::Shl &&
5072 L->getOperand(1) == BO->RHS) {
5073 uint64_t BitWidth = getTypeSizeInBits(BO->LHS->getType());
5074
5075 // If the shift count is not less than the bitwidth, the result of
5076 // the shift is undefined. Don't try to analyze it, because the
5077 // resolution chosen here may differ from the resolution chosen in
5078 // other parts of the compiler.
5079 if (CI->getValue().uge(BitWidth))
5080 break;
5081
5082 uint64_t Amt = BitWidth - CI->getZExtValue();
5083 if (Amt == BitWidth)
5084 return getSCEV(L->getOperand(0)); // shift by zero --> noop
5085 return getSignExtendExpr(
5086 getTruncateExpr(getSCEV(L->getOperand(0)),
5087 IntegerType::get(getContext(), Amt)),
5088 BO->LHS->getType());
5089 }
5090 break;
5091 }
5092 }
5093
5094 switch (U->getOpcode()) {
5095 case Instruction::Trunc:
5096 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
5097
5098 case Instruction::ZExt:
5099 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
5100
5101 case Instruction::SExt:
5102 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
5103
5104 case Instruction::BitCast:
5105 // BitCasts are no-op casts so we just eliminate the cast.
5106 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
5107 return getSCEV(U->getOperand(0));
5108 break;
5109
5110 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
5111 // lead to pointer expressions which cannot safely be expanded to GEPs,
5112 // because ScalarEvolution doesn't respect the GEP aliasing rules when
5113 // simplifying integer expressions.
5114
5115 case Instruction::GetElementPtr:
5116 return createNodeForGEP(cast<GEPOperator>(U));
5117
5118 case Instruction::PHI:
5119 return createNodeForPHI(cast<PHINode>(U));
5120
5121 case Instruction::Select:
5122 // U can also be a select constant expr, which let fall through. Since
5123 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
5124 // constant expressions cannot have instructions as operands, we'd have
5125 // returned getUnknown for a select constant expressions anyway.
5126 if (isa<Instruction>(U))
5127 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
5128 U->getOperand(1), U->getOperand(2));
5129 }
5130
5131 return getUnknown(V);
5132}
5133
5134
5135
5136//===----------------------------------------------------------------------===//
5137// Iteration Count Computation Code
5138//
5139
5140unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L) {
5141 if (BasicBlock *ExitingBB = L->getExitingBlock())
5142 return getSmallConstantTripCount(L, ExitingBB);
5143
5144 // No trip count information for multiple exits.
5145 return 0;
5146}
5147
5148/// getSmallConstantTripCount - Returns the maximum trip count of this loop as a
5149/// normal unsigned value. Returns 0 if the trip count is unknown or not
5150/// constant. Will also return 0 if the maximum trip count is very large (>=
5151/// 2^32).
5152///
5153/// This "trip count" assumes that control exits via ExitingBlock. More
5154/// precisely, it is the number of times that control may reach ExitingBlock
5155/// before taking the branch. For loops with multiple exits, it may not be the
5156/// number times that the loop header executes because the loop may exit
5157/// prematurely via another branch.
5158unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L,
5159 BasicBlock *ExitingBlock) {
5160 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5160, __PRETTY_FUNCTION__));
5161 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5162, __PRETTY_FUNCTION__))
5162 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5162, __PRETTY_FUNCTION__));
5163 const SCEVConstant *ExitCount =
5164 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
5165 if (!ExitCount)
5166 return 0;
5167
5168 ConstantInt *ExitConst = ExitCount->getValue();
5169
5170 // Guard against huge trip counts.
5171 if (ExitConst->getValue().getActiveBits() > 32)
5172 return 0;
5173
5174 // In case of integer overflow, this returns 0, which is correct.
5175 return ((unsigned)ExitConst->getZExtValue()) + 1;
5176}
5177
5178unsigned ScalarEvolution::getSmallConstantTripMultiple(Loop *L) {
5179 if (BasicBlock *ExitingBB = L->getExitingBlock())
5180 return getSmallConstantTripMultiple(L, ExitingBB);
5181
5182 // No trip multiple information for multiple exits.
5183 return 0;
5184}
5185
5186/// getSmallConstantTripMultiple - Returns the largest constant divisor of the
5187/// trip count of this loop as a normal unsigned value, if possible. This
5188/// means that the actual trip count is always a multiple of the returned
5189/// value (don't forget the trip count could very well be zero as well!).
5190///
5191/// Returns 1 if the trip count is unknown or not guaranteed to be the
5192/// multiple of a constant (which is also the case if the trip count is simply
5193/// constant, use getSmallConstantTripCount for that case), Will also return 1
5194/// if the trip count is very large (>= 2^32).
5195///
5196/// As explained in the comments for getSmallConstantTripCount, this assumes
5197/// that control exits the loop via ExitingBlock.
5198unsigned
5199ScalarEvolution::getSmallConstantTripMultiple(Loop *L,
5200 BasicBlock *ExitingBlock) {
5201 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5201, __PRETTY_FUNCTION__));
5202 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5203, __PRETTY_FUNCTION__))
5203 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5203, __PRETTY_FUNCTION__));
5204 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
5205 if (ExitCount == getCouldNotCompute())
5206 return 1;
5207
5208 // Get the trip count from the BE count by adding 1.
5209 const SCEV *TCMul = getAddExpr(ExitCount, getOne(ExitCount->getType()));
5210 // FIXME: SCEV distributes multiplication as V1*C1 + V2*C1. We could attempt
5211 // to factor simple cases.
5212 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(TCMul))
5213 TCMul = Mul->getOperand(0);
5214
5215 const SCEVConstant *MulC = dyn_cast<SCEVConstant>(TCMul);
5216 if (!MulC)
5217 return 1;
5218
5219 ConstantInt *Result = MulC->getValue();
5220
5221 // Guard against huge trip counts (this requires checking
5222 // for zero to handle the case where the trip count == -1 and the
5223 // addition wraps).
5224 if (!Result || Result->getValue().getActiveBits() > 32 ||
5225 Result->getValue().getActiveBits() == 0)
5226 return 1;
5227
5228 return (unsigned)Result->getZExtValue();
5229}
5230
5231// getExitCount - Get the expression for the number of loop iterations for which
5232// this loop is guaranteed not to exit via ExitingBlock. Otherwise return
5233// SCEVCouldNotCompute.
5234const SCEV *ScalarEvolution::getExitCount(Loop *L, BasicBlock *ExitingBlock) {
5235 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
5236}
5237
5238const SCEV *
5239ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
5240 SCEVUnionPredicate &Preds) {
5241 return getPredicatedBackedgeTakenInfo(L).getExact(this, &Preds);
5242}
5243
5244/// getBackedgeTakenCount - If the specified loop has a predictable
5245/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
5246/// object. The backedge-taken count is the number of times the loop header
5247/// will be branched to from within the loop. This is one less than the
5248/// trip count of the loop, since it doesn't count the first iteration,
5249/// when the header is branched to from outside the loop.
5250///
5251/// Note that it is not valid to call this method on a loop without a
5252/// loop-invariant backedge-taken count (see
5253/// hasLoopInvariantBackedgeTakenCount).
5254///
5255const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
5256 return getBackedgeTakenInfo(L).getExact(this);
5257}
5258
5259/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
5260/// return the least SCEV value that is known never to be less than the
5261/// actual backedge taken count.
5262const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
5263 return getBackedgeTakenInfo(L).getMax(this);
5264}
5265
5266/// PushLoopPHIs - Push PHI nodes in the header of the given loop
5267/// onto the given Worklist.
5268static void
5269PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
5270 BasicBlock *Header = L->getHeader();
5271
5272 // Push all Loop-header PHIs onto the Worklist stack.
5273 for (BasicBlock::iterator I = Header->begin();
5274 PHINode *PN = dyn_cast<PHINode>(I); ++I)
5275 Worklist.push_back(PN);
5276}
5277
5278const ScalarEvolution::BackedgeTakenInfo &
5279ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
5280 auto &BTI = getBackedgeTakenInfo(L);
5281 if (BTI.hasFullInfo())
5282 return BTI;
5283
5284 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
5285
5286 if (!Pair.second)
5287 return Pair.first->second;
5288
5289 BackedgeTakenInfo Result =
5290 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
5291
5292 return PredicatedBackedgeTakenCounts.find(L)->second = Result;
5293}
5294
5295const ScalarEvolution::BackedgeTakenInfo &
5296ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
5297 // Initially insert an invalid entry for this loop. If the insertion
5298 // succeeds, proceed to actually compute a backedge-taken count and
5299 // update the value. The temporary CouldNotCompute value tells SCEV
5300 // code elsewhere that it shouldn't attempt to request a new
5301 // backedge-taken count, which could result in infinite recursion.
5302 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
5303 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
5304 if (!Pair.second)
5305 return Pair.first->second;
5306
5307 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
5308 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
5309 // must be cleared in this scope.
5310 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
5311
5312 if (Result.getExact(this) != getCouldNotCompute()) {
5313 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5315, __PRETTY_FUNCTION__))
5314 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5315, __PRETTY_FUNCTION__))
5315 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5315, __PRETTY_FUNCTION__));
5316 ++NumTripCountsComputed;
5317 }
5318 else if (Result.getMax(this) == getCouldNotCompute() &&
5319 isa<PHINode>(L->getHeader()->begin())) {
5320 // Only count loops that have phi nodes as not being computable.
5321 ++NumTripCountsNotComputed;
5322 }
5323
5324 // Now that we know more about the trip count for this loop, forget any
5325 // existing SCEV values for PHI nodes in this loop since they are only
5326 // conservative estimates made without the benefit of trip count
5327 // information. This is similar to the code in forgetLoop, except that
5328 // it handles SCEVUnknown PHI nodes specially.
5329 if (Result.hasAnyInfo()) {
5330 SmallVector<Instruction *, 16> Worklist;
5331 PushLoopPHIs(L, Worklist);
5332
5333 SmallPtrSet<Instruction *, 8> Visited;
5334 while (!Worklist.empty()) {
5335 Instruction *I = Worklist.pop_back_val();
5336 if (!Visited.insert(I).second)
5337 continue;
5338
5339 ValueExprMapType::iterator It =
5340 ValueExprMap.find_as(static_cast<Value *>(I));
5341 if (It != ValueExprMap.end()) {
5342 const SCEV *Old = It->second;
5343
5344 // SCEVUnknown for a PHI either means that it has an unrecognized
5345 // structure, or it's a PHI that's in the progress of being computed
5346 // by createNodeForPHI. In the former case, additional loop trip
5347 // count information isn't going to change anything. In the later
5348 // case, createNodeForPHI will perform the necessary updates on its
5349 // own when it gets to that point.
5350 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
5351 forgetMemoizedResults(Old);
5352 ValueExprMap.erase(It);
5353 }
5354 if (PHINode *PN = dyn_cast<PHINode>(I))
5355 ConstantEvolutionLoopExitValue.erase(PN);
5356 }
5357
5358 PushDefUseChildren(I, Worklist);
5359 }
5360 }
5361
5362 // Re-lookup the insert position, since the call to
5363 // computeBackedgeTakenCount above could result in a
5364 // recusive call to getBackedgeTakenInfo (on a different
5365 // loop), which would invalidate the iterator computed
5366 // earlier.
5367 return BackedgeTakenCounts.find(L)->second = Result;
5368}
5369
5370/// forgetLoop - This method should be called by the client when it has
5371/// changed a loop in a way that may effect ScalarEvolution's ability to
5372/// compute a trip count, or if the loop is deleted.
5373void ScalarEvolution::forgetLoop(const Loop *L) {
5374 // Drop any stored trip count value.
5375 auto RemoveLoopFromBackedgeMap =
5376 [L](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
5377 auto BTCPos = Map.find(L);
5378 if (BTCPos != Map.end()) {
5379 BTCPos->second.clear();
5380 Map.erase(BTCPos);
5381 }
5382 };
5383
5384 RemoveLoopFromBackedgeMap(BackedgeTakenCounts);
5385 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts);
5386
5387 // Drop information about expressions based on loop-header PHIs.
5388 SmallVector<Instruction *, 16> Worklist;
5389 PushLoopPHIs(L, Worklist);
5390
5391 SmallPtrSet<Instruction *, 8> Visited;
5392 while (!Worklist.empty()) {
5393 Instruction *I = Worklist.pop_back_val();
5394 if (!Visited.insert(I).second)
5395 continue;
5396
5397 ValueExprMapType::iterator It =
5398 ValueExprMap.find_as(static_cast<Value *>(I));
5399 if (It != ValueExprMap.end()) {
5400 forgetMemoizedResults(It->second);
5401 ValueExprMap.erase(It);
5402 if (PHINode *PN = dyn_cast<PHINode>(I))
5403 ConstantEvolutionLoopExitValue.erase(PN);
5404 }
5405
5406 PushDefUseChildren(I, Worklist);
5407 }
5408
5409 // Forget all contained loops too, to avoid dangling entries in the
5410 // ValuesAtScopes map.
5411 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
5412 forgetLoop(*I);
5413}
5414
5415/// forgetValue - This method should be called by the client when it has
5416/// changed a value in a way that may effect its value, or which may
5417/// disconnect it from a def-use chain linking it to a loop.
5418void ScalarEvolution::forgetValue(Value *V) {
5419 Instruction *I = dyn_cast<Instruction>(V);
5420 if (!I) return;
5421
5422 // Drop information about expressions based on loop-header PHIs.
5423 SmallVector<Instruction *, 16> Worklist;
5424 Worklist.push_back(I);
5425
5426 SmallPtrSet<Instruction *, 8> Visited;
5427 while (!Worklist.empty()) {
5428 I = Worklist.pop_back_val();
5429 if (!Visited.insert(I).second)
5430 continue;
5431
5432 ValueExprMapType::iterator It =
5433 ValueExprMap.find_as(static_cast<Value *>(I));
5434 if (It != ValueExprMap.end()) {
5435 forgetMemoizedResults(It->second);
5436 ValueExprMap.erase(It);
5437 if (PHINode *PN = dyn_cast<PHINode>(I))
5438 ConstantEvolutionLoopExitValue.erase(PN);
5439 }
5440
5441 PushDefUseChildren(I, Worklist);
5442 }
5443}
5444
5445/// getExact - Get the exact loop backedge taken count considering all loop
5446/// exits. A computable result can only be returned for loops with a single
5447/// exit. Returning the minimum taken count among all exits is incorrect
5448/// because one of the loop's exit limit's may have been skipped. HowFarToZero
5449/// assumes that the limit of each loop test is never skipped. This is a valid
5450/// assumption as long as the loop exits via that test. For precise results, it
5451/// is the caller's responsibility to specify the relevant loop exit using
5452/// getExact(ExitingBlock, SE).
5453const SCEV *
5454ScalarEvolution::BackedgeTakenInfo::getExact(
5455 ScalarEvolution *SE, SCEVUnionPredicate *Preds) const {
5456 // If any exits were not computable, the loop is not computable.
5457 if (!ExitNotTaken.isCompleteList()) return SE->getCouldNotCompute();
5458
5459 // We need exactly one computable exit.
5460 if (!ExitNotTaken.ExitingBlock) return SE->getCouldNotCompute();
5461 assert(ExitNotTaken.ExactNotTaken && "uninitialized not-taken info")((ExitNotTaken.ExactNotTaken && "uninitialized not-taken info"
) ? static_cast<void> (0) : __assert_fail ("ExitNotTaken.ExactNotTaken && \"uninitialized not-taken info\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5461, __PRETTY_FUNCTION__));
5462
5463 const SCEV *BECount = nullptr;
5464 for (auto &ENT : ExitNotTaken) {
5465 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5465, __PRETTY_FUNCTION__));
5466
5467 if (!BECount)
5468 BECount = ENT.ExactNotTaken;
5469 else if (BECount != ENT.ExactNotTaken)
5470 return SE->getCouldNotCompute();
5471 if (Preds && ENT.getPred())
5472 Preds->add(ENT.getPred());
5473
5474 assert((Preds || ENT.hasAlwaysTruePred()) &&(((Preds || ENT.hasAlwaysTruePred()) && "Predicate should be always true!"
) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePred()) && \"Predicate should be always true!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5475, __PRETTY_FUNCTION__))
5475 "Predicate should be always true!")(((Preds || ENT.hasAlwaysTruePred()) && "Predicate should be always true!"
) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePred()) && \"Predicate should be always true!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5475, __PRETTY_FUNCTION__));
5476 }
5477
5478 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5478, __PRETTY_FUNCTION__));
5479 return BECount;
5480}
5481
5482/// getExact - Get the exact not taken count for this loop exit.
5483const SCEV *
5484ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
5485 ScalarEvolution *SE) const {
5486 for (auto &ENT : ExitNotTaken)
5487 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePred())
5488 return ENT.ExactNotTaken;
5489
5490 return SE->getCouldNotCompute();
5491}
5492
5493/// getMax - Get the max backedge taken count for the loop.
5494const SCEV *
5495ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
5496 for (auto &ENT : ExitNotTaken)
5497 if (!ENT.hasAlwaysTruePred())
5498 return SE->getCouldNotCompute();
5499
5500 return Max ? Max : SE->getCouldNotCompute();
5501}
5502
5503bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
5504 ScalarEvolution *SE) const {
5505 if (Max && Max != SE->getCouldNotCompute() && SE->hasOperand(Max, S))
5506 return true;
5507
5508 if (!ExitNotTaken.ExitingBlock)
5509 return false;
5510
5511 for (auto &ENT : ExitNotTaken)
5512 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
5513 SE->hasOperand(ENT.ExactNotTaken, S))
5514 return true;
5515
5516 return false;
5517}
5518
5519/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
5520/// computable exit into a persistent ExitNotTakenInfo array.
5521ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
5522 SmallVectorImpl<EdgeInfo> &ExitCounts, bool Complete, const SCEV *MaxCount)
5523 : Max(MaxCount) {
5524
5525 if (!Complete)
1
Assuming 'Complete' is not equal to 0
→
2
←
Taking false branch
→
5526 ExitNotTaken.setIncomplete();
5527
5528 unsigned NumExits = ExitCounts.size();
5529 if (NumExits == 0) return;
3
←
Assuming 'NumExits' is not equal to 0
→
4
←
Taking false branch
→
5530
5531 ExitNotTaken.ExitingBlock = ExitCounts[0].ExitBlock;
5532 ExitNotTaken.ExactNotTaken = ExitCounts[0].Taken;
5533
5534 // Determine the number of ExitNotTakenExtras structures that we need.
5535 unsigned ExtraInfoSize = 0;
5536 if (NumExits > 1)
5
←
Assuming 'NumExits' is > 1
→
6
←
Taking true branch
→
5537 ExtraInfoSize = 1 + std::count_if(std::next(ExitCounts.begin()),
5538 ExitCounts.end(), [](EdgeInfo &Entry) {
5539 return !Entry.Pred.isAlwaysTrue();
5540 });
5541 else if (!ExitCounts[0].Pred.isAlwaysTrue())
5542 ExtraInfoSize = 1;
5543
5544 ExitNotTakenExtras *ENT = nullptr;
5545
5546 // Allocate the ExitNotTakenExtras structures and initialize the first
5547 // element (ExitNotTaken).
5548 if (ExtraInfoSize > 0) {
7
←
Assuming 'ExtraInfoSize' is <= 0
→
8
←
Taking false branch
→
5549 ENT = new ExitNotTakenExtras[ExtraInfoSize];
5550 ExitNotTaken.ExtraInfo = &ENT[0];
5551 *ExitNotTaken.getPred() = std::move(ExitCounts[0].Pred);
5552 }
5553
5554 if (NumExits == 1)
9
←
Taking false branch
→
5555 return;
5556
5557 auto &Exits = ExitNotTaken.ExtraInfo->Exits;
5558
5559 // Handle the rare case of multiple computable exits.
5560 for (unsigned i = 1, PredPos = 1; i < NumExits; ++i) {
10
←
Loop condition is true. Entering loop body
→
5561 ExitNotTakenExtras *Ptr = nullptr;
5562 if (!ExitCounts[i].Pred.isAlwaysTrue()) {
11
←
Taking true branch
→
5563 Ptr = &ENT[PredPos++];
12
←
Null pointer value stored to 'Ptr'
→
5564 Ptr->Pred = std::move(ExitCounts[i].Pred);
13
←
Called C++ object pointer is null
5565 }
5566
5567 Exits.emplace_back(ExitCounts[i].ExitBlock, ExitCounts[i].Taken, Ptr);
5568 }
5569}
5570
5571/// clear - Invalidate this result and free the ExitNotTakenInfo array.
5572void ScalarEvolution::BackedgeTakenInfo::clear() {
5573 ExitNotTaken.ExitingBlock = nullptr;
5574 ExitNotTaken.ExactNotTaken = nullptr;
5575 delete[] ExitNotTaken.ExtraInfo;
5576}
5577
5578/// computeBackedgeTakenCount - Compute the number of times the backedge
5579/// of the specified loop will execute.
5580ScalarEvolution::BackedgeTakenInfo
5581ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
5582 bool AllowPredicates) {
5583 SmallVector<BasicBlock *, 8> ExitingBlocks;
5584 L->getExitingBlocks(ExitingBlocks);
5585
5586 SmallVector<EdgeInfo, 4> ExitCounts;
5587 bool CouldComputeBECount = true;
5588 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
5589 const SCEV *MustExitMaxBECount = nullptr;
5590 const SCEV *MayExitMaxBECount = nullptr;
5591
5592 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
5593 // and compute maxBECount.
5594 // Do a union of all the predicates here.
5595 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
5596 BasicBlock *ExitBB = ExitingBlocks[i];
5597 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
5598
5599 assert((AllowPredicates || EL.Pred.isAlwaysTrue()) &&(((AllowPredicates || EL.Pred.isAlwaysTrue()) && "Predicated exit limit when predicates are not allowed!"
) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Pred.isAlwaysTrue()) && \"Predicated exit limit when predicates are not allowed!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5600, __PRETTY_FUNCTION__))
5600 "Predicated exit limit when predicates are not allowed!")(((AllowPredicates || EL.Pred.isAlwaysTrue()) && "Predicated exit limit when predicates are not allowed!"
) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Pred.isAlwaysTrue()) && \"Predicated exit limit when predicates are not allowed!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5600, __PRETTY_FUNCTION__));
5601
5602 // 1. For each exit that can be computed, add an entry to ExitCounts.
5603 // CouldComputeBECount is true only if all exits can be computed.
5604 if (EL.Exact == getCouldNotCompute())
5605 // We couldn't compute an exact value for this exit, so
5606 // we won't be able to compute an exact value for the loop.
5607 CouldComputeBECount = false;
5608 else
5609 ExitCounts.emplace_back(EdgeInfo(ExitBB, EL.Exact, EL.Pred));
5610
5611 // 2. Derive the loop's MaxBECount from each exit's max number of
5612 // non-exiting iterations. Partition the loop exits into two kinds:
5613 // LoopMustExits and LoopMayExits.
5614 //
5615 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
5616 // is a LoopMayExit. If any computable LoopMustExit is found, then
5617 // MaxBECount is the minimum EL.Max of computable LoopMustExits. Otherwise,
5618 // MaxBECount is conservatively the maximum EL.Max, where CouldNotCompute is
5619 // considered greater than any computable EL.Max.
5620 if (EL.Max != getCouldNotCompute() && Latch &&
5621 DT.dominates(ExitBB, Latch)) {
5622 if (!MustExitMaxBECount)
5623 MustExitMaxBECount = EL.Max;
5624 else {
5625 MustExitMaxBECount =
5626 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.Max);
5627 }
5628 } else if (MayExitMaxBECount != getCouldNotCompute()) {
5629 if (!MayExitMaxBECount || EL.Max == getCouldNotCompute())
5630 MayExitMaxBECount = EL.Max;
5631 else {
5632 MayExitMaxBECount =
5633 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.Max);
5634 }
5635 }
5636 }
5637 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
5638 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
5639 return BackedgeTakenInfo(ExitCounts, CouldComputeBECount, MaxBECount);
5640}
5641
5642ScalarEvolution::ExitLimit
5643ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
5644 bool AllowPredicates) {
5645
5646 // Okay, we've chosen an exiting block. See what condition causes us to exit
5647 // at this block and remember the exit block and whether all other targets
5648 // lead to the loop header.
5649 bool MustExecuteLoopHeader = true;
5650 BasicBlock *Exit = nullptr;
5651 for (auto *SBB : successors(ExitingBlock))
5652 if (!L->contains(SBB)) {
5653 if (Exit) // Multiple exit successors.
5654 return getCouldNotCompute();
5655 Exit = SBB;
5656 } else if (SBB != L->getHeader()) {
5657 MustExecuteLoopHeader = false;
5658 }
5659
5660 // At this point, we know we have a conditional branch that determines whether
5661 // the loop is exited. However, we don't know if the branch is executed each
5662 // time through the loop. If not, then the execution count of the branch will
5663 // not be equal to the trip count of the loop.
5664 //
5665 // Currently we check for this by checking to see if the Exit branch goes to
5666 // the loop header. If so, we know it will always execute the same number of
5667 // times as the loop. We also handle the case where the exit block *is* the
5668 // loop header. This is common for un-rotated loops.
5669 //
5670 // If both of those tests fail, walk up the unique predecessor chain to the
5671 // header, stopping if there is an edge that doesn't exit the loop. If the
5672 // header is reached, the execution count of the branch will be equal to the
5673 // trip count of the loop.
5674 //
5675 // More extensive analysis could be done to handle more cases here.
5676 //
5677 if (!MustExecuteLoopHeader && ExitingBlock != L->getHeader()) {
5678 // The simple checks failed, try climbing the unique predecessor chain
5679 // up to the header.
5680 bool Ok = false;
5681 for (BasicBlock *BB = ExitingBlock; BB; ) {
5682 BasicBlock *Pred = BB->getUniquePredecessor();
5683 if (!Pred)
5684 return getCouldNotCompute();
5685 TerminatorInst *PredTerm = Pred->getTerminator();
5686 for (const BasicBlock *PredSucc : PredTerm->successors()) {
5687 if (PredSucc == BB)
5688 continue;
5689 // If the predecessor has a successor that isn't BB and isn't
5690 // outside the loop, assume the worst.
5691 if (L->contains(PredSucc))
5692 return getCouldNotCompute();
5693 }
5694 if (Pred == L->getHeader()) {
5695 Ok = true;
5696 break;
5697 }
5698 BB = Pred;
5699 }
5700 if (!Ok)
5701 return getCouldNotCompute();
5702 }
5703
5704 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
5705 TerminatorInst *Term = ExitingBlock->getTerminator();
5706 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
5707 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5707, __PRETTY_FUNCTION__));
5708 // Proceed to the next level to examine the exit condition expression.
5709 return computeExitLimitFromCond(
5710 L, BI->getCondition(), BI->getSuccessor(0), BI->getSuccessor(1),
5711 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
5712 }
5713
5714 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term))
5715 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
5716 /*ControlsExit=*/IsOnlyExit);
5717
5718 return getCouldNotCompute();
5719}
5720
5721/// computeExitLimitFromCond - Compute the number of times the
5722/// backedge of the specified loop will execute if its exit condition
5723/// were a conditional branch of ExitCond, TBB, and FBB.
5724///
5725/// @param ControlsExit is true if ExitCond directly controls the exit
5726/// branch. In this case, we can assume that the loop exits only if the
5727/// condition is true and can infer that failing to meet the condition prior to
5728/// integer wraparound results in undefined behavior.
5729ScalarEvolution::ExitLimit
5730ScalarEvolution::computeExitLimitFromCond(const Loop *L,
5731 Value *ExitCond,
5732 BasicBlock *TBB,
5733 BasicBlock *FBB,
5734 bool ControlsExit,
5735 bool AllowPredicates) {
5736 // Check if the controlling expression for this loop is an And or Or.
5737 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
5738 if (BO->getOpcode() == Instruction::And) {
5739 // Recurse on the operands of the and.
5740 bool EitherMayExit = L->contains(TBB);
5741 ExitLimit EL0 = computeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB,
5742 ControlsExit && !EitherMayExit,
5743 AllowPredicates);
5744 ExitLimit EL1 = computeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB,
5745 ControlsExit && !EitherMayExit,
5746 AllowPredicates);
5747 const SCEV *BECount = getCouldNotCompute();
5748 const SCEV *MaxBECount = getCouldNotCompute();
5749 if (EitherMayExit) {
5750 // Both conditions must be true for the loop to continue executing.
5751 // Choose the less conservative count.
5752 if (EL0.Exact == getCouldNotCompute() ||
5753 EL1.Exact == getCouldNotCompute())
5754 BECount = getCouldNotCompute();
5755 else
5756 BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
5757 if (EL0.Max == getCouldNotCompute())
5758 MaxBECount = EL1.Max;
5759 else if (EL1.Max == getCouldNotCompute())
5760 MaxBECount = EL0.Max;
5761 else
5762 MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
5763 } else {
5764 // Both conditions must be true at the same time for the loop to exit.
5765 // For now, be conservative.
5766 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5766, __PRETTY_FUNCTION__));
5767 if (EL0.Max == EL1.Max)
5768 MaxBECount = EL0.Max;
5769 if (EL0.Exact == EL1.Exact)
5770 BECount = EL0.Exact;
5771 }
5772
5773 SCEVUnionPredicate NP;
5774 NP.add(&EL0.Pred);
5775 NP.add(&EL1.Pred);
5776 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
5777 // to be more aggressive when computing BECount than when computing
5778 // MaxBECount. In these cases it is possible for EL0.Exact and EL1.Exact
5779 // to match, but for EL0.Max and EL1.Max to not.
5780 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
5781 !isa<SCEVCouldNotCompute>(BECount))
5782 MaxBECount = BECount;
5783
5784 return ExitLimit(BECount, MaxBECount, NP);
5785 }
5786 if (BO->getOpcode() == Instruction::Or) {
5787 // Recurse on the operands of the or.
5788 bool EitherMayExit = L->contains(FBB);
5789 ExitLimit EL0 = computeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB,
5790 ControlsExit && !EitherMayExit,
5791 AllowPredicates);
5792 ExitLimit EL1 = computeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB,
5793 ControlsExit && !EitherMayExit,
5794 AllowPredicates);
5795 const SCEV *BECount = getCouldNotCompute();
5796 const SCEV *MaxBECount = getCouldNotCompute();
5797 if (EitherMayExit) {
5798 // Both conditions must be false for the loop to continue executing.
5799 // Choose the less conservative count.
5800 if (EL0.Exact == getCouldNotCompute() ||
5801 EL1.Exact == getCouldNotCompute())
5802 BECount = getCouldNotCompute();
5803 else
5804 BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
5805 if (EL0.Max == getCouldNotCompute())
5806 MaxBECount = EL1.Max;
5807 else if (EL1.Max == getCouldNotCompute())
5808 MaxBECount = EL0.Max;
5809 else
5810 MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
5811 } else {
5812 // Both conditions must be false at the same time for the loop to exit.
5813 // For now, be conservative.
5814 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5814, __PRETTY_FUNCTION__));
5815 if (EL0.Max == EL1.Max)
5816 MaxBECount = EL0.Max;
5817 if (EL0.Exact == EL1.Exact)
5818 BECount = EL0.Exact;
5819 }
5820
5821 SCEVUnionPredicate NP;
5822 NP.add(&EL0.Pred);
5823 NP.add(&EL1.Pred);
5824 return ExitLimit(BECount, MaxBECount, NP);
5825 }
5826 }
5827
5828 // With an icmp, it may be feasible to compute an exact backedge-taken count.
5829 // Proceed to the next level to examine the icmp.
5830 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
5831 ExitLimit EL =
5832 computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit);
5833 if (EL.hasFullInfo() || !AllowPredicates)
5834 return EL;
5835
5836 // Try again, but use SCEV predicates this time.
5837 return computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit,
5838 /*AllowPredicates=*/true);
5839 }
5840
5841 // Check for a constant condition. These are normally stripped out by
5842 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
5843 // preserve the CFG and is temporarily leaving constant conditions
5844 // in place.
5845 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
5846 if (L->contains(FBB) == !CI->getZExtValue())
5847 // The backedge is always taken.
5848 return getCouldNotCompute();
5849 else
5850 // The backedge is never taken.
5851 return getZero(CI->getType());
5852 }
5853
5854 // If it's not an integer or pointer comparison then compute it the hard way.
5855 return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
5856}
5857
5858ScalarEvolution::ExitLimit
5859ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
5860 ICmpInst *ExitCond,
5861 BasicBlock *TBB,
5862 BasicBlock *FBB,
5863 bool ControlsExit,
5864 bool AllowPredicates) {
5865
5866 // If the condition was exit on true, convert the condition to exit on false
5867 ICmpInst::Predicate Cond;
5868 if (!L->contains(FBB))
5869 Cond = ExitCond->getPredicate();
5870 else
5871 Cond = ExitCond->getInversePredicate();
5872
5873 // Handle common loops like: for (X = "string"; *X; ++X)
5874 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
5875 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
5876 ExitLimit ItCnt =
5877 computeLoadConstantCompareExitLimit(LI, RHS, L, Cond);
5878 if (ItCnt.hasAnyInfo())
5879 return ItCnt;
5880 }
5881
5882 ExitLimit ShiftEL = computeShiftCompareExitLimit(
5883 ExitCond->getOperand(0), ExitCond->getOperand(1), L, Cond);
5884 if (ShiftEL.hasAnyInfo())
5885 return ShiftEL;
5886
5887 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
5888 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
5889
5890 // Try to evaluate any dependencies out of the loop.
5891 LHS = getSCEVAtScope(LHS, L);
5892 RHS = getSCEVAtScope(RHS, L);
5893
5894 // At this point, we would like to compute how many iterations of the
5895 // loop the predicate will return true for these inputs.
5896 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
5897 // If there is a loop-invariant, force it into the RHS.
5898 std::swap(LHS, RHS);
5899 Cond = ICmpInst::getSwappedPredicate(Cond);
5900 }
5901
5902 // Simplify the operands before analyzing them.
5903 (void)SimplifyICmpOperands(Cond, LHS, RHS);
5904
5905 // If we have a comparison of a chrec against a constant, try to use value
5906 // ranges to answer this query.
5907 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
5908 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
5909 if (AddRec->getLoop() == L) {
5910 // Form the constant range.
5911 ConstantRange CompRange(
5912 ICmpInst::makeConstantRange(Cond, RHSC->getAPInt()));
5913
5914 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
5915 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
5916 }
5917
5918 switch (Cond) {
5919 case ICmpInst::ICMP_NE: { // while (X != Y)
5920 // Convert to: while (X-Y != 0)
5921 ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
5922 AllowPredicates);
5923 if (EL.hasAnyInfo()) return EL;
5924 break;
5925 }
5926 case ICmpInst::ICMP_EQ: { // while (X == Y)
5927 // Convert to: while (X-Y == 0)
5928 ExitLimit EL = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
5929 if (EL.hasAnyInfo()) return EL;
5930 break;
5931 }
5932 case ICmpInst::ICMP_SLT:
5933 case ICmpInst::ICMP_ULT: { // while (X < Y)
5934 bool IsSigned = Cond == ICmpInst::ICMP_SLT;
5935 ExitLimit EL = HowManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
5936 AllowPredicates);
5937 if (EL.hasAnyInfo()) return EL;
5938 break;
5939 }
5940 case ICmpInst::ICMP_SGT:
5941 case ICmpInst::ICMP_UGT: { // while (X > Y)
5942 bool IsSigned = Cond == ICmpInst::ICMP_SGT;
5943 ExitLimit EL =
5944 HowManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
5945 AllowPredicates);
5946 if (EL.hasAnyInfo()) return EL;
5947 break;
5948 }
5949 default:
5950 break;
5951 }
5952 return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
5953}
5954
5955ScalarEvolution::ExitLimit
5956ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
5957 SwitchInst *Switch,
5958 BasicBlock *ExitingBlock,
5959 bool ControlsExit) {
5960 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5960, __PRETTY_FUNCTION__));
5961
5962 // Give up if the exit is the default dest of a switch.
5963 if (Switch->getDefaultDest() == ExitingBlock)
5964 return getCouldNotCompute();
5965
5966 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5967, __PRETTY_FUNCTION__))
5967 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5967, __PRETTY_FUNCTION__));
5968 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
5969 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
5970
5971 // while (X != Y) --> while (X-Y != 0)
5972 ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
5973 if (EL.hasAnyInfo())
5974 return EL;
5975
5976 return getCouldNotCompute();
5977}
5978
5979static ConstantInt *
5980EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
5981 ScalarEvolution &SE) {
5982 const SCEV *InVal = SE.getConstant(C);
5983 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
5984 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5985, __PRETTY_FUNCTION__))
5985 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 5985, __PRETTY_FUNCTION__));
5986 return cast<SCEVConstant>(Val)->getValue();
5987}
5988
5989/// computeLoadConstantCompareExitLimit - Given an exit condition of
5990/// 'icmp op load X, cst', try to see if we can compute the backedge
5991/// execution count.
5992ScalarEvolution::ExitLimit
5993ScalarEvolution::computeLoadConstantCompareExitLimit(
5994 LoadInst *LI,
5995 Constant *RHS,
5996 const Loop *L,
5997 ICmpInst::Predicate predicate) {
5998
5999 if (LI->isVolatile()) return getCouldNotCompute();
6000
6001 // Check to see if the loaded pointer is a getelementptr of a global.
6002 // TODO: Use SCEV instead of manually grubbing with GEPs.
6003 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
6004 if (!GEP) return getCouldNotCompute();
6005
6006 // Make sure that it is really a constant global we are gepping, with an
6007 // initializer, and make sure the first IDX is really 0.
6008 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
6009 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
6010 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
6011 !cast<Constant>(GEP->getOperand(1))->isNullValue())
6012 return getCouldNotCompute();
6013
6014 // Okay, we allow one non-constant index into the GEP instruction.
6015 Value *VarIdx = nullptr;
6016 std::vector<Constant*> Indexes;
6017 unsigned VarIdxNum = 0;
6018 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
6019 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
6020 Indexes.push_back(CI);
6021 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
6022 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
6023 VarIdx = GEP->getOperand(i);
6024 VarIdxNum = i-2;
6025 Indexes.push_back(nullptr);
6026 }
6027
6028 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
6029 if (!VarIdx)
6030 return getCouldNotCompute();
6031
6032 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
6033 // Check to see if X is a loop variant variable value now.
6034 const SCEV *Idx = getSCEV(VarIdx);
6035 Idx = getSCEVAtScope(Idx, L);
6036
6037 // We can only recognize very limited forms of loop index expressions, in
6038 // particular, only affine AddRec's like {C1,+,C2}.
6039 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
6040 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
6041 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
6042 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
6043 return getCouldNotCompute();
6044
6045 unsigned MaxSteps = MaxBruteForceIterations;
6046 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
6047 ConstantInt *ItCst = ConstantInt::get(
6048 cast<IntegerType>(IdxExpr->getType()), IterationNum);
6049 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
6050
6051 // Form the GEP offset.
6052 Indexes[VarIdxNum] = Val;
6053
6054 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
6055 Indexes);
6056 if (!Result) break; // Cannot compute!
6057
6058 // Evaluate the condition for this iteration.
6059 Result = ConstantExpr::getICmp(predicate, Result, RHS);
6060 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
6061 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
6062 ++NumArrayLenItCounts;
6063 return getConstant(ItCst); // Found terminating iteration!
6064 }
6065 }
6066 return getCouldNotCompute();
6067}
6068
6069ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
6070 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
6071 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
6072 if (!RHS)
6073 return getCouldNotCompute();
6074
6075 const BasicBlock *Latch = L->getLoopLatch();
6076 if (!Latch)
6077 return getCouldNotCompute();
6078
6079 const BasicBlock *Predecessor = L->getLoopPredecessor();
6080 if (!Predecessor)
6081 return getCouldNotCompute();
6082
6083 // Return true if V is of the form "LHS `shift_op` <positive constant>".
6084 // Return LHS in OutLHS and shift_opt in OutOpCode.
6085 auto MatchPositiveShift =
6086 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
6087
6088 using namespace PatternMatch;
6089
6090 ConstantInt *ShiftAmt;
6091 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6092 OutOpCode = Instruction::LShr;
6093 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6094 OutOpCode = Instruction::AShr;
6095 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6096 OutOpCode = Instruction::Shl;
6097 else
6098 return false;
6099
6100 return ShiftAmt->getValue().isStrictlyPositive();
6101 };
6102
6103 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
6104 //
6105 // loop:
6106 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
6107 // %iv.shifted = lshr i32 %iv, <positive constant>
6108 //
6109 // Return true on a succesful match. Return the corresponding PHI node (%iv
6110 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
6111 auto MatchShiftRecurrence =
6112 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
6113 Optional<Instruction::BinaryOps> PostShiftOpCode;
6114
6115 {
6116 Instruction::BinaryOps OpC;
6117 Value *V;
6118
6119 // If we encounter a shift instruction, "peel off" the shift operation,
6120 // and remember that we did so. Later when we inspect %iv's backedge
6121 // value, we will make sure that the backedge value uses the same
6122 // operation.
6123 //
6124 // Note: the peeled shift operation does not have to be the same
6125 // instruction as the one feeding into the PHI's backedge value. We only
6126 // really care about it being the same *kind* of shift instruction --
6127 // that's all that is required for our later inferences to hold.
6128 if (MatchPositiveShift(LHS, V, OpC)) {
6129 PostShiftOpCode = OpC;
6130 LHS = V;
6131 }
6132 }
6133
6134 PNOut = dyn_cast<PHINode>(LHS);
6135 if (!PNOut || PNOut->getParent() != L->getHeader())
6136 return false;
6137
6138 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
6139 Value *OpLHS;
6140
6141 return
6142 // The backedge value for the PHI node must be a shift by a positive
6143 // amount
6144 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
6145
6146 // of the PHI node itself
6147 OpLHS == PNOut &&
6148
6149 // and the kind of shift should be match the kind of shift we peeled
6150 // off, if any.
6151 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
6152 };
6153
6154 PHINode *PN;
6155 Instruction::BinaryOps OpCode;
6156 if (!MatchShiftRecurrence(LHS, PN, OpCode))
6157 return getCouldNotCompute();
6158
6159 const DataLayout &DL = getDataLayout();
6160
6161 // The key rationale for this optimization is that for some kinds of shift
6162 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
6163 // within a finite number of iterations. If the condition guarding the
6164 // backedge (in the sense that the backedge is taken if the condition is true)
6165 // is false for the value the shift recurrence stabilizes to, then we know
6166 // that the backedge is taken only a finite number of times.
6167
6168 ConstantInt *StableValue = nullptr;
6169 switch (OpCode) {
6170 default:
6171 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6171);
6172
6173 case Instruction::AShr: {
6174 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
6175 // bitwidth(K) iterations.
6176 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
6177 bool KnownZero, KnownOne;
6178 ComputeSignBit(FirstValue, KnownZero, KnownOne, DL, 0, nullptr,
6179 Predecessor->getTerminator(), &DT);
6180 auto *Ty = cast<IntegerType>(RHS->getType());
6181 if (KnownZero)
6182 StableValue = ConstantInt::get(Ty, 0);
6183 else if (KnownOne)
6184 StableValue = ConstantInt::get(Ty, -1, true);
6185 else
6186 return getCouldNotCompute();
6187
6188 break;
6189 }
6190 case Instruction::LShr:
6191 case Instruction::Shl:
6192 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
6193 // stabilize to 0 in at most bitwidth(K) iterations.
6194 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
6195 break;
6196 }
6197
6198 auto *Result =
6199 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
6200 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6201, __PRETTY_FUNCTION__))
6201 "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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6201, __PRETTY_FUNCTION__));
6202
6203 if (Result->isZeroValue()) {
6204 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
6205 const SCEV *UpperBound =
6206 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
6207 SCEVUnionPredicate P;
6208 return ExitLimit(getCouldNotCompute(), UpperBound, P);
6209 }
6210
6211 return getCouldNotCompute();
6212}
6213
6214/// CanConstantFold - Return true if we can constant fold an instruction of the
6215/// specified type, assuming that all operands were constants.
6216static bool CanConstantFold(const Instruction *I) {
6217 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
6218 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
6219 isa<LoadInst>(I))
6220 return true;
6221
6222 if (const CallInst *CI = dyn_cast<CallInst>(I))
6223 if (const Function *F = CI->getCalledFunction())
6224 return canConstantFoldCallTo(F);
6225 return false;
6226}
6227
6228/// Determine whether this instruction can constant evolve within this loop
6229/// assuming its operands can all constant evolve.
6230static bool canConstantEvolve(Instruction *I, const Loop *L) {
6231 // An instruction outside of the loop can't be derived from a loop PHI.
6232 if (!L->contains(I)) return false;
6233
6234 if (isa<PHINode>(I)) {
6235 // We don't currently keep track of the control flow needed to evaluate
6236 // PHIs, so we cannot handle PHIs inside of loops.
6237 return L->getHeader() == I->getParent();
6238 }
6239
6240 // If we won't be able to constant fold this expression even if the operands
6241 // are constants, bail early.
6242 return CanConstantFold(I);
6243}
6244
6245/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
6246/// recursing through each instruction operand until reaching a loop header phi.
6247static PHINode *
6248getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
6249 DenseMap<Instruction *, PHINode *> &PHIMap) {
6250
6251 // Otherwise, we can evaluate this instruction if all of its operands are
6252 // constant or derived from a PHI node themselves.
6253 PHINode *PHI = nullptr;
6254 for (Value *Op : UseInst->operands()) {
6255 if (isa<Constant>(Op)) continue;
6256
6257 Instruction *OpInst = dyn_cast<Instruction>(Op);
6258 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
6259
6260 PHINode *P = dyn_cast<PHINode>(OpInst);
6261 if (!P)
6262 // If this operand is already visited, reuse the prior result.
6263 // We may have P != PHI if this is the deepest point at which the
6264 // inconsistent paths meet.
6265 P = PHIMap.lookup(OpInst);
6266 if (!P) {
6267 // Recurse and memoize the results, whether a phi is found or not.
6268 // This recursive call invalidates pointers into PHIMap.
6269 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap);
6270 PHIMap[OpInst] = P;
6271 }
6272 if (!P)
6273 return nullptr; // Not evolving from PHI
6274 if (PHI && PHI != P)
6275 return nullptr; // Evolving from multiple different PHIs.
6276 PHI = P;
6277 }
6278 // This is a expression evolving from a constant PHI!
6279 return PHI;
6280}
6281
6282/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
6283/// in the loop that V is derived from. We allow arbitrary operations along the
6284/// way, but the operands of an operation must either be constants or a value
6285/// derived from a constant PHI. If this expression does not fit with these
6286/// constraints, return null.
6287static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
6288 Instruction *I = dyn_cast<Instruction>(V);
6289 if (!I || !canConstantEvolve(I, L)) return nullptr;
6290
6291 if (PHINode *PN = dyn_cast<PHINode>(I))
6292 return PN;
6293
6294 // Record non-constant instructions contained by the loop.
6295 DenseMap<Instruction *, PHINode *> PHIMap;
6296 return getConstantEvolvingPHIOperands(I, L, PHIMap);
6297}
6298
6299/// EvaluateExpression - Given an expression that passes the
6300/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
6301/// in the loop has the value PHIVal. If we can't fold this expression for some
6302/// reason, return null.
6303static Constant *EvaluateExpression(Value *V, const Loop *L,
6304 DenseMap<Instruction *, Constant *> &Vals,
6305 const DataLayout &DL,
6306 const TargetLibraryInfo *TLI) {
6307 // Convenient constant check, but redundant for recursive calls.
6308 if (Constant *C = dyn_cast<Constant>(V)) return C;
6309 Instruction *I = dyn_cast<Instruction>(V);
6310 if (!I) return nullptr;
6311
6312 if (Constant *C = Vals.lookup(I)) return C;
6313
6314 // An instruction inside the loop depends on a value outside the loop that we
6315 // weren't given a mapping for, or a value such as a call inside the loop.
6316 if (!canConstantEvolve(I, L)) return nullptr;
6317
6318 // An unmapped PHI can be due to a branch or another loop inside this loop,
6319 // or due to this not being the initial iteration through a loop where we
6320 // couldn't compute the evolution of this particular PHI last time.
6321 if (isa<PHINode>(I)) return nullptr;
6322
6323 std::vector<Constant*> Operands(I->getNumOperands());
6324
6325 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
6326 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
6327 if (!Operand) {
6328 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
6329 if (!Operands[i]) return nullptr;
6330 continue;
6331 }
6332 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
6333 Vals[Operand] = C;
6334 if (!C) return nullptr;
6335 Operands[i] = C;
6336 }
6337
6338 if (CmpInst *CI = dyn_cast<CmpInst>(I))
6339 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
6340 Operands[1], DL, TLI);
6341 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6342 if (!LI->isVolatile())
6343 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
6344 }
6345 return ConstantFoldInstOperands(I, Operands, DL, TLI);
6346}
6347
6348
6349// If every incoming value to PN except the one for BB is a specific Constant,
6350// return that, else return nullptr.
6351static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
6352 Constant *IncomingVal = nullptr;
6353
6354 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
6355 if (PN->getIncomingBlock(i) == BB)
6356 continue;
6357
6358 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
6359 if (!CurrentVal)
6360 return nullptr;
6361
6362 if (IncomingVal != CurrentVal) {
6363 if (IncomingVal)
6364 return nullptr;
6365 IncomingVal = CurrentVal;
6366 }
6367 }
6368
6369 return IncomingVal;
6370}
6371
6372/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
6373/// in the header of its containing loop, we know the loop executes a
6374/// constant number of times, and the PHI node is just a recurrence
6375/// involving constants, fold it.
6376Constant *
6377ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
6378 const APInt &BEs,
6379 const Loop *L) {
6380 auto I = ConstantEvolutionLoopExitValue.find(PN);
6381 if (I != ConstantEvolutionLoopExitValue.end())
6382 return I->second;
6383
6384 if (BEs.ugt(MaxBruteForceIterations))
6385 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
6386
6387 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
6388
6389 DenseMap<Instruction *, Constant *> CurrentIterVals;
6390 BasicBlock *Header = L->getHeader();
6391 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6391, __PRETTY_FUNCTION__));
6392
6393 BasicBlock *Latch = L->getLoopLatch();
6394 if (!Latch)
6395 return nullptr;
6396
6397 for (auto &I : *Header) {
6398 PHINode *PHI = dyn_cast<PHINode>(&I);
6399 if (!PHI) break;
6400 auto *StartCST = getOtherIncomingValue(PHI, Latch);
6401 if (!StartCST) continue;
6402 CurrentIterVals[PHI] = StartCST;
6403 }
6404 if (!CurrentIterVals.count(PN))
6405 return RetVal = nullptr;
6406
6407 Value *BEValue = PN->getIncomingValueForBlock(Latch);
6408
6409 // Execute the loop symbolically to determine the exit value.
6410 if (BEs.getActiveBits() >= 32)
6411 return RetVal = nullptr; // More than 2^32-1 iterations?? Not doing it!
6412
6413 unsigned NumIterations = BEs.getZExtValue(); // must be in range
6414 unsigned IterationNum = 0;
6415 const DataLayout &DL = getDataLayout();
6416 for (; ; ++IterationNum) {
6417 if (IterationNum == NumIterations)
6418 return RetVal = CurrentIterVals[PN]; // Got exit value!
6419
6420 // Compute the value of the PHIs for the next iteration.
6421 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
6422 DenseMap<Instruction *, Constant *> NextIterVals;
6423 Constant *NextPHI =
6424 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
6425 if (!NextPHI)
6426 return nullptr; // Couldn't evaluate!
6427 NextIterVals[PN] = NextPHI;
6428
6429 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
6430
6431 // Also evaluate the other PHI nodes. However, we don't get to stop if we
6432 // cease to be able to evaluate one of them or if they stop evolving,
6433 // because that doesn't necessarily prevent us from computing PN.
6434 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
6435 for (const auto &I : CurrentIterVals) {
6436 PHINode *PHI = dyn_cast<PHINode>(I.first);
6437 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
6438 PHIsToCompute.emplace_back(PHI, I.second);
6439 }
6440 // We use two distinct loops because EvaluateExpression may invalidate any
6441 // iterators into CurrentIterVals.
6442 for (const auto &I : PHIsToCompute) {
6443 PHINode *PHI = I.first;
6444 Constant *&NextPHI = NextIterVals[PHI];
6445 if (!NextPHI) { // Not already computed.
6446 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
6447 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
6448 }
6449 if (NextPHI != I.second)
6450 StoppedEvolving = false;
6451 }
6452
6453 // If all entries in CurrentIterVals == NextIterVals then we can stop
6454 // iterating, the loop can't continue to change.
6455 if (StoppedEvolving)
6456 return RetVal = CurrentIterVals[PN];
6457
6458 CurrentIterVals.swap(NextIterVals);
6459 }
6460}
6461
6462const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
6463 Value *Cond,
6464 bool ExitWhen) {
6465 PHINode *PN = getConstantEvolvingPHI(Cond, L);
6466 if (!PN) return getCouldNotCompute();
6467
6468 // If the loop is canonicalized, the PHI will have exactly two entries.
6469 // That's the only form we support here.
6470 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
6471
6472 DenseMap<Instruction *, Constant *> CurrentIterVals;
6473 BasicBlock *Header = L->getHeader();
6474 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6474, __PRETTY_FUNCTION__));
6475
6476 BasicBlock *Latch = L->getLoopLatch();
6477 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-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6477, __PRETTY_FUNCTION__));
6478
6479 for (auto &I : *Header) {
6480 PHINode *PHI = dyn_cast<PHINode>(&I);
6481 if (!PHI)
6482 break;
6483 auto *StartCST = getOtherIncomingValue(PHI, Latch);
6484 if (!StartCST) continue;
6485 CurrentIterVals[PHI] = StartCST;
6486 }
6487 if (!CurrentIterVals.count(PN))
6488 return getCouldNotCompute();
6489
6490 // Okay, we find a PHI node that defines the trip count of this loop. Execute
6491 // the loop symbolically to determine when the condition gets a value of
6492 // "ExitWhen".
6493 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
6494 const DataLayout &DL = getDataLayout();
6495 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
6496 auto *CondVal = dyn_cast_or_null<ConstantInt>(
6497 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
6498
6499 // Couldn't symbolically evaluate.
6500 if (!CondVal) return getCouldNotCompute();
6501
6502 if (CondVal->getValue() == uint64_t(ExitWhen)) {
6503 ++NumBruteForceTripCountsComputed;
6504 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
6505 }
6506
6507 // Update all the PHI nodes for the next iteration.
6508 DenseMap<Instruction *, Constant *> NextIterVals;
6509
6510 // Create a list of which PHIs we need to compute. We want to do this before
6511 // calling EvaluateExpression on them because that may invalidate iterators
6512 // into CurrentIterVals.
6513 SmallVector<PHINode *, 8> PHIsToCompute;
6514 for (const auto &I : CurrentIterVals) {
6515 PHINode *PHI = dyn_cast<PHINode>(I.first);
6516 if (!PHI || PHI->getParent() != Header) continue;
6517 PHIsToCompute.push_back(PHI);
6518 }
6519 for (PHINode *PHI : PHIsToCompute) {
6520 Constant *&NextPHI = NextIterVals[PHI];
6521 if (NextPHI) continue; // Already computed!
6522
6523 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
6524 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
6525 }
6526 CurrentIterVals.swap(NextIterVals);
6527 }
6528
6529 // Too many iterations were needed to evaluate.
6530 return getCouldNotCompute();
6531}
6532
6533/// getSCEVAtScope - Return a SCEV expression for the specified value
6534/// at the specified scope in the program. The L value specifies a loop
6535/// nest to evaluate the expression at, where null is the top-level or a
6536/// specified loop is immediately inside of the loop.
6537///
6538/// This method can be used to compute the exit value for a variable defined
6539/// in a loop by querying what the value will hold in the parent loop.
6540///
6541/// In the case that a relevant loop exit value cannot be computed, the
6542/// original value V is returned.
6543const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
6544 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
6545 ValuesAtScopes[V];
6546 // Check to see if we've folded this expression at this loop before.
6547 for (auto &LS : Values)
6548 if (LS.first == L)
6549 return LS.second ? LS.second : V;
6550
6551 Values.emplace_back(L, nullptr);
6552
6553 // Otherwise compute it.
6554 const SCEV *C = computeSCEVAtScope(V, L);
6555 for (auto &LS : reverse(ValuesAtScopes[V]))
6556 if (LS.first == L) {
6557 LS.second = C;
6558 break;
6559 }
6560 return C;
6561}
6562
6563/// This builds up a Constant using the ConstantExpr interface. That way, we
6564/// will return Constants for objects which aren't represented by a
6565/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
6566/// Returns NULL if the SCEV isn't representable as a Constant.
6567static Constant *BuildConstantFromSCEV(const SCEV *V) {
6568 switch (static_cast<SCEVTypes>(V->getSCEVType())) {
6569 case scCouldNotCompute:
6570 case scAddRecExpr:
6571 break;
6572 case scConstant:
6573 return cast<SCEVConstant>(V)->getValue();
6574 case scUnknown:
6575 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
6576 case scSignExtend: {
6577 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
6578 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
6579 return ConstantExpr::getSExt(CastOp, SS->getType());
6580 break;
6581 }
6582 case scZeroExtend: {
6583 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
6584 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
6585 return ConstantExpr::getZExt(CastOp, SZ->getType());
6586 break;
6587 }
6588 case scTruncate: {
6589 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
6590 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
6591 return ConstantExpr::getTrunc(CastOp, ST->getType());
6592 break;
6593 }
6594 case scAddExpr: {
6595 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
6596 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
6597 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
6598 unsigned AS = PTy->getAddressSpace();
6599 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
6600 C = ConstantExpr::getBitCast(C, DestPtrTy);
6601 }
6602 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
6603 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
6604 if (!C2) return nullptr;
6605
6606 // First pointer!
6607 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
6608 unsigned AS = C2->getType()->getPointerAddressSpace();
6609 std::swap(C, C2);
6610 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
6611 // The offsets have been converted to bytes. We can add bytes to an
6612 // i8* by GEP with the byte count in the first index.
6613 C = ConstantExpr::getBitCast(C, DestPtrTy);
6614 }
6615
6616 // Don't bother trying to sum two pointers. We probably can't
6617 // statically compute a load that results from it anyway.
6618 if (C2->getType()->isPointerTy())
6619 return nullptr;
6620
6621 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
6622 if (PTy->getElementType()->isStructTy())
6623 C2 = ConstantExpr::getIntegerCast(
6624 C2, Type::getInt32Ty(C->getContext()), true);
6625 C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2);
6626 } else
6627 C = ConstantExpr::getAdd(C, C2);
6628 }
6629 return C;
6630 }
6631 break;
6632 }
6633 case scMulExpr: {
6634 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
6635 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
6636 // Don't bother with pointers at all.
6637 if (C->getType()->isPointerTy()) return nullptr;
6638 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
6639 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
6640 if (!C2 || C2->getType()->isPointerTy()) return nullptr;
6641 C = ConstantExpr::getMul(C, C2);
6642 }
6643 return C;
6644 }
6645 break;
6646 }
6647 case scUDivExpr: {
6648 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
6649 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
6650 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
6651 if (LHS->getType() == RHS->getType())
6652 return ConstantExpr::getUDiv(LHS, RHS);
6653 break;
6654 }
6655 case scSMaxExpr:
6656 case scUMaxExpr:
6657 break; // TODO: smax, umax.
6658 }
6659 return nullptr;
6660}
6661
6662const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
6663 if (isa<SCEVConstant>(V)) return V;
6664
6665 // If this instruction is evolved from a constant-evolving PHI, compute the
6666 // exit value from the loop without using SCEVs.
6667 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
6668 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
6669 const Loop *LI = this->LI[I->getParent()];
6670 if (LI && LI->getParentLoop() == L) // Looking for loop exit value.
6671 if (PHINode *PN = dyn_cast<PHINode>(I))
6672 if (PN->getParent() == LI->getHeader()) {
6673 // Okay, there is no closed form solution for the PHI node. Check
6674 // to see if the loop that contains it has a known backedge-taken
6675 // count. If so, we may be able to force computation of the exit
6676 // value.
6677 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI);
6678 if (const SCEVConstant *BTCC =
6679 dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
6680 // Okay, we know how many times the containing loop executes. If
6681 // this is a constant evolving PHI node, get the final value at
6682 // the specified iteration number.
6683 Constant *RV =
6684 getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI);
6685 if (RV) return getSCEV(RV);
6686 }
6687 }
6688
6689 // Okay, this is an expression that we cannot symbolically evaluate
6690 // into a SCEV. Check to see if it's possible to symbolically evaluate
6691 // the arguments into constants, and if so, try to constant propagate the
6692 // result. This is particularly useful for computing loop exit values.
6693 if (CanConstantFold(I)) {
6694 SmallVector<Constant *, 4> Operands;
6695 bool MadeImprovement = false;
6696 for (Value *Op : I->operands()) {
6697 if (Constant *C = dyn_cast<Constant>(Op)) {
6698 Operands.push_back(C);
6699 continue;
6700 }
6701
6702 // If any of the operands is non-constant and if they are
6703 // non-integer and non-pointer, don't even try to analyze them
6704 // with scev techniques.
6705 if (!isSCEVable(Op->getType()))
6706 return V;
6707
6708 const SCEV *OrigV = getSCEV(Op);
6709 const SCEV *OpV = getSCEVAtScope(OrigV, L);
6710 MadeImprovement |= OrigV != OpV;
6711
6712 Constant *C = BuildConstantFromSCEV(OpV);
6713 if (!C) return V;
6714 if (C->getType() != Op->getType())
6715 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
6716 Op->getType(),
6717 false),
6718 C, Op->getType());
6719 Operands.push_back(C);
6720 }
6721
6722 // Check to see if getSCEVAtScope actually made an improvement.
6723 if (MadeImprovement) {
6724 Constant *C = nullptr;
6725 const DataLayout &DL = getDataLayout();
6726 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
6727 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
6728 Operands[1], DL, &TLI);
6729 else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
6730 if (!LI->isVolatile())
6731 C = ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
6732 } else
6733 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
6734 if (!C) return V;
6735 return getSCEV(C);
6736 }
6737 }
6738 }
6739
6740 // This is some other type of SCEVUnknown, just return it.
6741 return V;
6742 }
6743
6744 if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
6745 // Avoid performing the look-up in the common case where the specified
6746 // expression has no loop-variant portions.
6747 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
6748 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
6749 if (OpAtScope != Comm->getOperand(i)) {
6750 // Okay, at least one of these operands is loop variant but might be
6751 // foldable. Build a new instance of the folded commutative expression.
6752 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
6753 Comm->op_begin()+i);
6754 NewOps.push_back(OpAtScope);
6755
6756 for (++i; i != e; ++i) {
6757 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
6758 NewOps.push_back(OpAtScope);
6759 }
6760 if (isa<SCEVAddExpr>(Comm))
6761 return getAddExpr(NewOps);
6762 if (isa<SCEVMulExpr>(Comm))
6763 return getMulExpr(NewOps);
6764 if (isa<SCEVSMaxExpr>(Comm))
6765 return getSMaxExpr(NewOps);
6766 if (isa<SCEVUMaxExpr>(Comm))
6767 return getUMaxExpr(NewOps);
6768 llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6768);
6769 }
6770 }
6771 // If we got here, all operands are loop invariant.
6772 return Comm;
6773 }
6774
6775 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
6776 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
6777 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
6778 if (LHS == Div->getLHS() && RHS == Div->getRHS())
6779 return Div; // must be loop invariant
6780 return getUDivExpr(LHS, RHS);
6781 }
6782
6783 // If this is a loop recurrence for a loop that does not contain L, then we
6784 // are dealing with the final value computed by the loop.
6785 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
6786 // First, attempt to evaluate each operand.
6787 // Avoid performing the look-up in the common case where the specified
6788 // expression has no loop-variant portions.
6789 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
6790 const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
6791 if (OpAtScope == AddRec->getOperand(i))
6792 continue;
6793
6794 // Okay, at least one of these operands is loop variant but might be
6795 // foldable. Build a new instance of the folded commutative expression.
6796 SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
6797 AddRec->op_begin()+i);
6798 NewOps.push_back(OpAtScope);
6799 for (++i; i != e; ++i)
6800 NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
6801
6802 const SCEV *FoldedRec =
6803 getAddRecExpr(NewOps, AddRec->getLoop(),
6804 AddRec->getNoWrapFlags(SCEV::FlagNW));
6805 AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
6806 // The addrec may be folded to a nonrecurrence, for example, if the
6807 // induction variable is multiplied by zero after constant folding. Go
6808 // ahead and return the folded value.
6809 if (!AddRec)
6810 return FoldedRec;
6811 break;
6812 }
6813
6814 // If the scope is outside the addrec's loop, evaluate it by using the
6815 // loop exit value of the addrec.
6816 if (!AddRec->getLoop()->contains(L)) {
6817 // To evaluate this recurrence, we need to know how many times the AddRec
6818 // loop iterates. Compute this now.
6819 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
6820 if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
6821
6822 // Then, evaluate the AddRec.
6823 return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
6824 }
6825
6826 return AddRec;
6827 }
6828
6829 if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) {
6830 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
6831 if (Op == Cast->getOperand())
6832 return Cast; // must be loop invariant
6833 return getZeroExtendExpr(Op, Cast->getType());
6834 }
6835
6836 if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) {
6837 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
6838 if (Op == Cast->getOperand())
6839 return Cast; // must be loop invariant
6840 return getSignExtendExpr(Op, Cast->getType());
6841 }
6842
6843 if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) {
6844 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
6845 if (Op == Cast->getOperand())
6846 return Cast; // must be loop invariant
6847 return getTruncateExpr(Op, Cast->getType());
6848 }
6849
6850 llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6850);
6851}
6852
6853/// getSCEVAtScope - This is a convenience function which does
6854/// getSCEVAtScope(getSCEV(V), L).
6855const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
6856 return getSCEVAtScope(getSCEV(V), L);
6857}
6858
6859/// SolveLinEquationWithOverflow - Finds the minimum unsigned root of the
6860/// following equation:
6861///
6862/// A * X = B (mod N)
6863///
6864/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
6865/// A and B isn't important.
6866///
6867/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
6868static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const APInt &B,
6869 ScalarEvolution &SE) {
6870 uint32_t BW = A.getBitWidth();
6871 assert(BW == B.getBitWidth() && "Bit widths must be the same.")((BW == B.getBitWidth() && "Bit widths must be the same."
) ? static_cast<void> (0) : __assert_fail ("BW == B.getBitWidth() && \"Bit widths must be the same.\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6871, __PRETTY_FUNCTION__));
6872 assert(A != 0 && "A must be non-zero.")((A != 0 && "A must be non-zero.") ? static_cast<void
> (0) : __assert_fail ("A != 0 && \"A must be non-zero.\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6872, __PRETTY_FUNCTION__));
6873
6874 // 1. D = gcd(A, N)
6875 //
6876 // The gcd of A and N may have only one prime factor: 2. The number of
6877 // trailing zeros in A is its multiplicity
6878 uint32_t Mult2 = A.countTrailingZeros();
6879 // D = 2^Mult2
6880
6881 // 2. Check if B is divisible by D.
6882 //
6883 // B is divisible by D if and only if the multiplicity of prime factor 2 for B
6884 // is not less than multiplicity of this prime factor for D.
6885 if (B.countTrailingZeros() < Mult2)
6886 return SE.getCouldNotCompute();
6887
6888 // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
6889 // modulo (N / D).
6890 //
6891 // (N / D) may need BW+1 bits in its representation. Hence, we'll use this
6892 // bit width during computations.
6893 APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
6894 APInt Mod(BW + 1, 0);
6895 Mod.setBit(BW - Mult2); // Mod = N / D
6896 APInt I = AD.multiplicativeInverse(Mod);
6897
6898 // 4. Compute the minimum unsigned root of the equation:
6899 // I * (B / D) mod (N / D)
6900 APInt Result = (I * B.lshr(Mult2).zext(BW + 1)).urem(Mod);
6901
6902 // The result is guaranteed to be less than 2^BW so we may truncate it to BW
6903 // bits.
6904 return SE.getConstant(Result.trunc(BW));
6905}
6906
6907/// SolveQuadraticEquation - Find the roots of the quadratic equation for the
6908/// given quadratic chrec {L,+,M,+,N}. This returns either the two roots (which
6909/// might be the same) or two SCEVCouldNotCompute objects.
6910///
6911static std::pair<const SCEV *,const SCEV *>
6912SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
6913 assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!")((AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!"
) ? static_cast<void> (0) : __assert_fail ("AddRec->getNumOperands() == 3 && \"This is not a quadratic chrec!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 6913, __PRETTY_FUNCTION__));
6914 const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
6915 const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
6916 const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
6917
6918 // We currently can only solve this if the coefficients are constants.
6919 if (!LC || !MC || !NC) {
6920 const SCEV *CNC = SE.getCouldNotCompute();
6921 return {CNC, CNC};
6922 }
6923
6924 uint32_t BitWidth = LC->getAPInt().getBitWidth();
6925 const APInt &L = LC->getAPInt();
6926 const APInt &M = MC->getAPInt();
6927 const APInt &N = NC->getAPInt();
6928 APInt Two(BitWidth, 2);
6929 APInt Four(BitWidth, 4);
6930
6931 {
6932 using namespace APIntOps;
6933 const APInt& C = L;
6934 // Convert from chrec coefficients to polynomial coefficients AX^2+BX+C
6935 // The B coefficient is M-N/2
6936 APInt B(M);
6937 B -= sdiv(N,Two);
6938
6939 // The A coefficient is N/2
6940 APInt A(N.sdiv(Two));
6941
6942 // Compute the B^2-4ac term.
6943 APInt SqrtTerm(B);
6944 SqrtTerm *= B;
6945 SqrtTerm -= Four * (A * C);
6946
6947 if (SqrtTerm.isNegative()) {
6948 // The loop is provably infinite.
6949 const SCEV *CNC = SE.getCouldNotCompute();
6950 return {CNC, CNC};
6951 }
6952
6953 // Compute sqrt(B^2-4ac). This is guaranteed to be the nearest
6954 // integer value or else APInt::sqrt() will assert.
6955 APInt SqrtVal(SqrtTerm.sqrt());
6956
6957 // Compute the two solutions for the quadratic formula.
6958 // The divisions must be performed as signed divisions.
6959 APInt NegB(-B);
6960 APInt TwoA(A << 1);
6961 if (TwoA.isMinValue()) {
6962 const SCEV *CNC = SE.getCouldNotCompute();
6963 return {CNC, CNC};
6964 }
6965
6966 LLVMContext &Context = SE.getContext();
6967
6968 ConstantInt *Solution1 =
6969 ConstantInt::get(Context, (NegB + SqrtVal).sdiv(TwoA));
6970 ConstantInt *Solution2 =
6971 ConstantInt::get(Context, (NegB - SqrtVal).sdiv(TwoA));
6972
6973 return {SE.getConstant(Solution1), SE.getConstant(Solution2)};
6974 } // end APIntOps namespace
6975}
6976
6977/// HowFarToZero - Return the number of times a backedge comparing the specified
6978/// value to zero will execute. If not computable, return CouldNotCompute.
6979///
6980/// This is only used for loops with a "x != y" exit test. The exit condition is
6981/// now expressed as a single expression, V = x-y. So the exit test is
6982/// effectively V != 0. We know and take advantage of the fact that this
6983/// expression only being used in a comparison by zero context.
6984ScalarEvolution::ExitLimit
6985ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit,
6986 bool AllowPredicates) {
6987 SCEVUnionPredicate P;
6988 // If the value is a constant
6989 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
6990 // If the value is already zero, the branch will execute zero times.
6991 if (C->getValue()->isZero()) return C;
6992 return getCouldNotCompute(); // Otherwise it will loop infinitely.
6993 }
6994
6995 const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V);
6996 if (!AddRec && AllowPredicates)
6997 // Try to make this an AddRec using runtime tests, in the first X
6998 // iterations of this loop, where X is the SCEV expression found by the
6999 // algorithm below.
7000 AddRec = convertSCEVToAddRecWithPredicates(V, L, P);
7001
7002 if (!AddRec || AddRec->getLoop() != L)
7003 return getCouldNotCompute();
7004
7005 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
7006 // the quadratic equation to solve it.
7007 if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
7008 std::pair<const SCEV *,const SCEV *> Roots =
7009 SolveQuadraticEquation(AddRec, *this);
7010 const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
7011 const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
7012 if (R1 && R2) {
7013 // Pick the smallest positive root value.
7014 if (ConstantInt *CB =
7015 dyn_cast<ConstantInt>(ConstantExpr::getICmp(CmpInst::ICMP_ULT,
7016 R1->getValue(),
7017 R2->getValue()))) {
7018 if (!CB->getZExtValue())
7019 std::swap(R1, R2); // R1 is the minimum root now.
7020
7021 // We can only use this value if the chrec ends up with an exact zero
7022 // value at this index. When solving for "X*X != 5", for example, we
7023 // should not accept a root of 2.
7024 const SCEV *Val = AddRec->evaluateAtIteration(R1, *this);
7025 if (Val->isZero())
7026 return ExitLimit(R1, R1, P); // We found a quadratic root!
7027 }
7028 }
7029 return getCouldNotCompute();
7030 }
7031
7032 // Otherwise we can only handle this if it is affine.
7033 if (!AddRec->isAffine())
7034 return getCouldNotCompute();
7035
7036 // If this is an affine expression, the execution count of this branch is
7037 // the minimum unsigned root of the following equation:
7038 //
7039 // Start + Step*N = 0 (mod 2^BW)
7040 //
7041 // equivalent to:
7042 //
7043 // Step*N = -Start (mod 2^BW)
7044 //
7045 // where BW is the common bit width of Start and Step.
7046
7047 // Get the initial value for the loop.
7048 const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
7049 const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
7050
7051 // For now we handle only constant steps.
7052 //
7053 // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
7054 // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
7055 // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
7056 // We have not yet seen any such cases.
7057 const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
7058 if (!StepC || StepC->getValue()->equalsInt(0))
7059 return getCouldNotCompute();
7060
7061 // For positive steps (counting up until unsigned overflow):
7062 // N = -Start/Step (as unsigned)
7063 // For negative steps (counting down to zero):
7064 // N = Start/-Step
7065 // First compute the unsigned distance from zero in the direction of Step.
7066 bool CountDown = StepC->getAPInt().isNegative();
7067 const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
7068
7069 // Handle unitary steps, which cannot wraparound.
7070 // 1*N = -Start; -1*N = Start (mod 2^BW), so:
7071 // N = Distance (as unsigned)
7072 if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) {
7073 ConstantRange CR = getUnsignedRange(Start);
7074 const SCEV *MaxBECount;
7075 if (!CountDown && CR.getUnsignedMin().isMinValue())
7076 // When counting up, the worst starting value is 1, not 0.
7077 MaxBECount = CR.getUnsignedMax().isMinValue()
7078 ? getConstant(APInt::getMinValue(CR.getBitWidth()))
7079 : getConstant(APInt::getMaxValue(CR.getBitWidth()));
7080 else
7081 MaxBECount = getConstant(CountDown ? CR.getUnsignedMax()
7082 : -CR.getUnsignedMin());
7083 return ExitLimit(Distance, MaxBECount, P);
7084 }
7085
7086 // As a special case, handle the instance where Step is a positive power of
7087 // two. In this case, determining whether Step divides Distance evenly can be
7088 // done by counting and comparing the number of trailing zeros of Step and
7089 // Distance.
7090 if (!CountDown) {
7091 const APInt &StepV = StepC->getAPInt();
7092 // StepV.isPowerOf2() returns true if StepV is an positive power of two. It
7093 // also returns true if StepV is maximally negative (eg, INT_MIN), but that
7094 // case is not handled as this code is guarded by !CountDown.
7095 if (StepV.isPowerOf2() &&
7096 GetMinTrailingZeros(Distance) >= StepV.countTrailingZeros()) {
7097 // Here we've constrained the equation to be of the form
7098 //
7099 // 2^(N + k) * Distance' = (StepV == 2^N) * X (mod 2^W) ... (0)
7100 //
7101 // where we're operating on a W bit wide integer domain and k is
7102 // non-negative. The smallest unsigned solution for X is the trip count.
7103 //
7104 // (0) is equivalent to:
7105 //
7106 // 2^(N + k) * Distance' - 2^N * X = L * 2^W
7107 // <=> 2^N(2^k * Distance' - X) = L * 2^(W - N) * 2^N
7108 // <=> 2^k * Distance' - X = L * 2^(W - N)
7109 // <=> 2^k * Distance' = L * 2^(W - N) + X ... (1)
7110 //
7111 // The smallest X satisfying (1) is unsigned remainder of dividing the LHS
7112 // by 2^(W - N).
7113 //
7114 // <=> X = 2^k * Distance' URem 2^(W - N) ... (2)
7115 //
7116 // E.g. say we're solving
7117 //
7118 // 2 * Val = 2 * X (in i8) ... (3)
7119 //
7120 // then from (2), we get X = Val URem i8 128 (k = 0 in this case).
7121 //
7122 // Note: It is tempting to solve (3) by setting X = Val, but Val is not
7123 // necessarily the smallest unsigned value of X that satisfies (3).
7124 // E.g. if Val is i8 -127 then the smallest value of X that satisfies (3)
7125 // is i8 1, not i8 -127
7126
7127 const auto *ModuloResult = getUDivExactExpr(Distance, Step);
7128
7129 // Since SCEV does not have a URem node, we construct one using a truncate
7130 // and a zero extend.
7131
7132 unsigned NarrowWidth = StepV.getBitWidth() - StepV.countTrailingZeros();
7133 auto *NarrowTy = IntegerType::get(getContext(), NarrowWidth);
7134 auto *WideTy = Distance->getType();
7135
7136 const SCEV *Limit =
7137 getZeroExtendExpr(getTruncateExpr(ModuloResult, NarrowTy), WideTy);
7138 return ExitLimit(Limit, Limit, P);
7139 }
7140 }
7141
7142 // If the condition controls loop exit (the loop exits only if the expression
7143 // is true) and the addition is no-wrap we can use unsigned divide to
7144 // compute the backedge count. In this case, the step may not divide the
7145 // distance, but we don't care because if the condition is "missed" the loop
7146 // will have undefined behavior due to wrapping.
7147 if (ControlsExit && AddRec->hasNoSelfWrap()) {
7148 const SCEV *Exact =
7149 getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
7150 return ExitLimit(Exact, Exact, P);
7151 }
7152
7153 // Then, try to solve the above equation provided that Start is constant.
7154 if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start)) {
7155 const SCEV *E = SolveLinEquationWithOverflow(
7156 StepC->getValue()->getValue(), -StartC->getValue()->getValue(), *this);
7157 return ExitLimit(E, E, P);
7158 }
7159 return getCouldNotCompute();
7160}
7161
7162/// HowFarToNonZero - Return the number of times a backedge checking the
7163/// specified value for nonzero will execute. If not computable, return
7164/// CouldNotCompute
7165ScalarEvolution::ExitLimit
7166ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) {
7167 // Loops that look like: while (X == 0) are very strange indeed. We don't
7168 // handle them yet except for the trivial case. This could be expanded in the
7169 // future as needed.
7170
7171 // If the value is a constant, check to see if it is known to be non-zero
7172 // already. If so, the backedge will execute zero times.
7173 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
7174 if (!C->getValue()->isNullValue())
7175 return getZero(C->getType());
7176 return getCouldNotCompute(); // Otherwise it will loop infinitely.
7177 }
7178
7179 // We could implement others, but I really doubt anyone writes loops like
7180 // this, and if they did, they would already be constant folded.
7181 return getCouldNotCompute();
7182}
7183
7184/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
7185/// (which may not be an immediate predecessor) which has exactly one
7186/// successor from which BB is reachable, or null if no such block is
7187/// found.
7188///
7189std::pair<BasicBlock *, BasicBlock *>
7190ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
7191 // If the block has a unique predecessor, then there is no path from the
7192 // predecessor to the block that does not go through the direct edge
7193 // from the predecessor to the block.
7194 if (BasicBlock *Pred = BB->getSinglePredecessor())
7195 return {Pred, BB};
7196
7197 // A loop's header is defined to be a block that dominates the loop.
7198 // If the header has a unique predecessor outside the loop, it must be
7199 // a block that has exactly one successor that can reach the loop.
7200 if (Loop *L = LI.getLoopFor(BB))
7201 return {L->getLoopPredecessor(), L->getHeader()};
7202
7203 return {nullptr, nullptr};
7204}
7205
7206/// HasSameValue - SCEV structural equivalence is usually sufficient for
7207/// testing whether two expressions are equal, however for the purposes of
7208/// looking for a condition guarding a loop, it can be useful to be a little
7209/// more general, since a front-end may have replicated the controlling
7210/// expression.
7211///
7212static bool HasSameValue(const SCEV *A, const SCEV *B) {
7213 // Quick check to see if they are the same SCEV.
7214 if (A == B) return true;
7215
7216 auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) {
7217 // Not all instructions that are "identical" compute the same value. For
7218 // instance, two distinct alloca instructions allocating the same type are
7219 // identical and do not read memory; but compute distinct values.
7220 return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A));
7221 };
7222
7223 // Otherwise, if they're both SCEVUnknown, it's possible that they hold
7224 // two different instructions with the same value. Check for this case.
7225 if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
7226 if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
7227 if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
7228 if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
7229 if (ComputesEqualValues(AI, BI))
7230 return true;
7231
7232 // Otherwise assume they may have a different value.
7233 return false;
7234}
7235
7236/// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
7237/// predicate Pred. Return true iff any changes were made.
7238///
7239bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
7240 const SCEV *&LHS, const SCEV *&RHS,
7241 unsigned Depth) {
7242 bool Changed = false;
7243
7244 // If we hit the max recursion limit bail out.
7245 if (Depth >= 3)
7246 return false;
7247
7248 // Canonicalize a constant to the right side.
7249 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
7250 // Check for both operands constant.
7251 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
7252 if (ConstantExpr::getICmp(Pred,
7253 LHSC->getValue(),
7254 RHSC->getValue())->isNullValue())
7255 goto trivially_false;
7256 else
7257 goto trivially_true;
7258 }
7259 // Otherwise swap the operands to put the constant on the right.
7260 std::swap(LHS, RHS);
7261 Pred = ICmpInst::getSwappedPredicate(Pred);
7262 Changed = true;
7263 }
7264
7265 // If we're comparing an addrec with a value which is loop-invariant in the
7266 // addrec's loop, put the addrec on the left. Also make a dominance check,
7267 // as both operands could be addrecs loop-invariant in each other's loop.
7268 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
7269 const Loop *L = AR->getLoop();
7270 if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
7271 std::swap(LHS, RHS);
7272 Pred = ICmpInst::getSwappedPredicate(Pred);
7273 Changed = true;
7274 }
7275 }
7276
7277 // If there's a constant operand, canonicalize comparisons with boundary
7278 // cases, and canonicalize *-or-equal comparisons to regular comparisons.
7279 if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
7280 const APInt &RA = RC->getAPInt();
7281 switch (Pred) {
7282 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7282);
7283 case ICmpInst::ICMP_EQ:
7284 case ICmpInst::ICMP_NE:
7285 // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
7286 if (!RA)
7287 if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
7288 if (const SCEVMulExpr *ME = dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
7289 if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
7290 ME->getOperand(0)->isAllOnesValue()) {
7291 RHS = AE->getOperand(1);
7292 LHS = ME->getOperand(1);
7293 Changed = true;
7294 }
7295 break;
7296 case ICmpInst::ICMP_UGE:
7297 if ((RA - 1).isMinValue()) {
7298 Pred = ICmpInst::ICMP_NE;
7299 RHS = getConstant(RA - 1);
7300 Changed = true;
7301 break;
7302 }
7303 if (RA.isMaxValue()) {
7304 Pred = ICmpInst::ICMP_EQ;
7305 Changed = true;
7306 break;
7307 }
7308 if (RA.isMinValue()) goto trivially_true;
7309
7310 Pred = ICmpInst::ICMP_UGT;
7311 RHS = getConstant(RA - 1);
7312 Changed = true;
7313 break;
7314 case ICmpInst::ICMP_ULE:
7315 if ((RA + 1).isMaxValue()) {
7316 Pred = ICmpInst::ICMP_NE;
7317 RHS = getConstant(RA + 1);
7318 Changed = true;
7319 break;
7320 }
7321 if (RA.isMinValue()) {
7322 Pred = ICmpInst::ICMP_EQ;
7323 Changed = true;
7324 break;
7325 }
7326 if (RA.isMaxValue()) goto trivially_true;
7327
7328 Pred = ICmpInst::ICMP_ULT;
7329 RHS = getConstant(RA + 1);
7330 Changed = true;
7331 break;
7332 case ICmpInst::ICMP_SGE:
7333 if ((RA - 1).isMinSignedValue()) {
7334 Pred = ICmpInst::ICMP_NE;
7335 RHS = getConstant(RA - 1);
7336 Changed = true;
7337 break;
7338 }
7339 if (RA.isMaxSignedValue()) {
7340 Pred = ICmpInst::ICMP_EQ;
7341 Changed = true;
7342 break;
7343 }
7344 if (RA.isMinSignedValue()) goto trivially_true;
7345
7346 Pred = ICmpInst::ICMP_SGT;
7347 RHS = getConstant(RA - 1);
7348 Changed = true;
7349 break;
7350 case ICmpInst::ICMP_SLE:
7351 if ((RA + 1).isMaxSignedValue()) {
7352 Pred = ICmpInst::ICMP_NE;
7353 RHS = getConstant(RA + 1);
7354 Changed = true;
7355 break;
7356 }
7357 if (RA.isMinSignedValue()) {
7358 Pred = ICmpInst::ICMP_EQ;
7359 Changed = true;
7360 break;
7361 }
7362 if (RA.isMaxSignedValue()) goto trivially_true;
7363
7364 Pred = ICmpInst::ICMP_SLT;
7365 RHS = getConstant(RA + 1);
7366 Changed = true;
7367 break;
7368 case ICmpInst::ICMP_UGT:
7369 if (RA.isMinValue()) {
7370 Pred = ICmpInst::ICMP_NE;
7371 Changed = true;
7372 break;
7373 }
7374 if ((RA + 1).isMaxValue()) {
7375 Pred = ICmpInst::ICMP_EQ;
7376 RHS = getConstant(RA + 1);
7377 Changed = true;
7378 break;
7379 }
7380 if (RA.isMaxValue()) goto trivially_false;
7381 break;
7382 case ICmpInst::ICMP_ULT:
7383 if (RA.isMaxValue()) {
7384 Pred = ICmpInst::ICMP_NE;
7385 Changed = true;
7386 break;
7387 }
7388 if ((RA - 1).isMinValue()) {
7389 Pred = ICmpInst::ICMP_EQ;
7390 RHS = getConstant(RA - 1);
7391 Changed = true;
7392 break;
7393 }
7394 if (RA.isMinValue()) goto trivially_false;
7395 break;
7396 case ICmpInst::ICMP_SGT:
7397 if (RA.isMinSignedValue()) {
7398 Pred = ICmpInst::ICMP_NE;
7399 Changed = true;
7400 break;
7401 }
7402 if ((RA + 1).isMaxSignedValue()) {
7403 Pred = ICmpInst::ICMP_EQ;
7404 RHS = getConstant(RA + 1);
7405 Changed = true;
7406 break;
7407 }
7408 if (RA.isMaxSignedValue()) goto trivially_false;
7409 break;
7410 case ICmpInst::ICMP_SLT:
7411 if (RA.isMaxSignedValue()) {
7412 Pred = ICmpInst::ICMP_NE;
7413 Changed = true;
7414 break;
7415 }
7416 if ((RA - 1).isMinSignedValue()) {
7417 Pred = ICmpInst::ICMP_EQ;
7418 RHS = getConstant(RA - 1);
7419 Changed = true;
7420 break;
7421 }
7422 if (RA.isMinSignedValue()) goto trivially_false;
7423 break;
7424 }
7425 }
7426
7427 // Check for obvious equality.
7428 if (HasSameValue(LHS, RHS)) {
7429 if (ICmpInst::isTrueWhenEqual(Pred))
7430 goto trivially_true;
7431 if (ICmpInst::isFalseWhenEqual(Pred))
7432 goto trivially_false;
7433 }
7434
7435 // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
7436 // adding or subtracting 1 from one of the operands.
7437 switch (Pred) {
7438 case ICmpInst::ICMP_SLE:
7439 if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) {
7440 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
7441 SCEV::FlagNSW);
7442 Pred = ICmpInst::ICMP_SLT;
7443 Changed = true;
7444 } else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) {
7445 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
7446 SCEV::FlagNSW);
7447 Pred = ICmpInst::ICMP_SLT;
7448 Changed = true;
7449 }
7450 break;
7451 case ICmpInst::ICMP_SGE:
7452 if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) {
7453 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
7454 SCEV::FlagNSW);
7455 Pred = ICmpInst::ICMP_SGT;
7456 Changed = true;
7457 } else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) {
7458 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
7459 SCEV::FlagNSW);
7460 Pred = ICmpInst::ICMP_SGT;
7461 Changed = true;
7462 }
7463 break;
7464 case ICmpInst::ICMP_ULE:
7465 if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) {
7466 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
7467 SCEV::FlagNUW);
7468 Pred = ICmpInst::ICMP_ULT;
7469 Changed = true;
7470 } else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) {
7471 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS);
7472 Pred = ICmpInst::ICMP_ULT;
7473 Changed = true;
7474 }
7475 break;
7476 case ICmpInst::ICMP_UGE:
7477 if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) {
7478 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS);
7479 Pred = ICmpInst::ICMP_UGT;
7480 Changed = true;
7481 } else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) {
7482 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
7483 SCEV::FlagNUW);
7484 Pred = ICmpInst::ICMP_UGT;
7485 Changed = true;
7486 }
7487 break;
7488 default:
7489 break;
7490 }
7491
7492 // TODO: More simplifications are possible here.
7493
7494 // Recursively simplify until we either hit a recursion limit or nothing
7495 // changes.
7496 if (Changed)
7497 return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1);
7498
7499 return Changed;
7500
7501trivially_true:
7502 // Return 0 == 0.
7503 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
7504 Pred = ICmpInst::ICMP_EQ;
7505 return true;
7506
7507trivially_false:
7508 // Return 0 != 0.
7509 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
7510 Pred = ICmpInst::ICMP_NE;
7511 return true;
7512}
7513
7514bool ScalarEvolution::isKnownNegative(const SCEV *S) {
7515 return getSignedRange(S).getSignedMax().isNegative();
7516}
7517
7518bool ScalarEvolution::isKnownPositive(const SCEV *S) {
7519 return getSignedRange(S).getSignedMin().isStrictlyPositive();
7520}
7521
7522bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
7523 return !getSignedRange(S).getSignedMin().isNegative();
7524}
7525
7526bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
7527 return !getSignedRange(S).getSignedMax().isStrictlyPositive();
7528}
7529
7530bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
7531 return isKnownNegative(S) || isKnownPositive(S);
7532}
7533
7534bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
7535 const SCEV *LHS, const SCEV *RHS) {
7536 // Canonicalize the inputs first.
7537 (void)SimplifyICmpOperands(Pred, LHS, RHS);
7538
7539 // If LHS or RHS is an addrec, check to see if the condition is true in
7540 // every iteration of the loop.
7541 // If LHS and RHS are both addrec, both conditions must be true in
7542 // every iteration of the loop.
7543 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
7544 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
7545 bool LeftGuarded = false;
7546 bool RightGuarded = false;
7547 if (LAR) {
7548 const Loop *L = LAR->getLoop();
7549 if (isLoopEntryGuardedByCond(L, Pred, LAR->getStart(), RHS) &&
7550 isLoopBackedgeGuardedByCond(L, Pred, LAR->getPostIncExpr(*this), RHS)) {
7551 if (!RAR) return true;
7552 LeftGuarded = true;
7553 }
7554 }
7555 if (RAR) {
7556 const Loop *L = RAR->getLoop();
7557 if (isLoopEntryGuardedByCond(L, Pred, LHS, RAR->getStart()) &&
7558 isLoopBackedgeGuardedByCond(L, Pred, LHS, RAR->getPostIncExpr(*this))) {
7559 if (!LAR) return true;
7560 RightGuarded = true;
7561 }
7562 }
7563 if (LeftGuarded && RightGuarded)
7564 return true;
7565
7566 if (isKnownPredicateViaSplitting(Pred, LHS, RHS))
7567 return true;
7568
7569 // Otherwise see what can be done with known constant ranges.
7570 return isKnownPredicateViaConstantRanges(Pred, LHS, RHS);
7571}
7572
7573bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS,
7574 ICmpInst::Predicate Pred,
7575 bool &Increasing) {
7576 bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing);
7577
7578#ifndef NDEBUG
7579 // Verify an invariant: inverting the predicate should turn a monotonically
7580 // increasing change to a monotonically decreasing one, and vice versa.
7581 bool IncreasingSwapped;
7582 bool ResultSwapped = isMonotonicPredicateImpl(
7583 LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped);
7584
7585 assert(Result == ResultSwapped && "should be able to analyze both!")((Result == ResultSwapped && "should be able to analyze both!"
) ? static_cast<void> (0) : __assert_fail ("Result == ResultSwapped && \"should be able to analyze both!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7585, __PRETTY_FUNCTION__));
7586 if (ResultSwapped)
7587 assert(Increasing == !IncreasingSwapped &&((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate"
) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7588, __PRETTY_FUNCTION__))
7588 "monotonicity should flip as we flip the predicate")((Increasing == !IncreasingSwapped && "monotonicity should flip as we flip the predicate"
) ? static_cast<void> (0) : __assert_fail ("Increasing == !IncreasingSwapped && \"monotonicity should flip as we flip the predicate\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7588, __PRETTY_FUNCTION__));
7589#endif
7590
7591 return Result;
7592}
7593
7594bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
7595 ICmpInst::Predicate Pred,
7596 bool &Increasing) {
7597
7598 // A zero step value for LHS means the induction variable is essentially a
7599 // loop invariant value. We don't really depend on the predicate actually
7600 // flipping from false to true (for increasing predicates, and the other way
7601 // around for decreasing predicates), all we care about is that *if* the
7602 // predicate changes then it only changes from false to true.
7603 //
7604 // A zero step value in itself is not very useful, but there may be places
7605 // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
7606 // as general as possible.
7607
7608 switch (Pred) {
7609 default:
7610 return false; // Conservative answer
7611
7612 case ICmpInst::ICMP_UGT:
7613 case ICmpInst::ICMP_UGE:
7614 case ICmpInst::ICMP_ULT:
7615 case ICmpInst::ICMP_ULE:
7616 if (!LHS->hasNoUnsignedWrap())
7617 return false;
7618
7619 Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE;
7620 return true;
7621
7622 case ICmpInst::ICMP_SGT:
7623 case ICmpInst::ICMP_SGE:
7624 case ICmpInst::ICMP_SLT:
7625 case ICmpInst::ICMP_SLE: {
7626 if (!LHS->hasNoSignedWrap())
7627 return false;
7628
7629 const SCEV *Step = LHS->getStepRecurrence(*this);
7630
7631 if (isKnownNonNegative(Step)) {
7632 Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE;
7633 return true;
7634 }
7635
7636 if (isKnownNonPositive(Step)) {
7637 Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE;
7638 return true;
7639 }
7640
7641 return false;
7642 }
7643
7644 }
7645
7646 llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7646);
7647}
7648
7649bool ScalarEvolution::isLoopInvariantPredicate(
7650 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L,
7651 ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS,
7652 const SCEV *&InvariantRHS) {
7653
7654 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
7655 if (!isLoopInvariant(RHS, L)) {
7656 if (!isLoopInvariant(LHS, L))
7657 return false;
7658
7659 std::swap(LHS, RHS);
7660 Pred = ICmpInst::getSwappedPredicate(Pred);
7661 }
7662
7663 const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS);
7664 if (!ArLHS || ArLHS->getLoop() != L)
7665 return false;
7666
7667 bool Increasing;
7668 if (!isMonotonicPredicate(ArLHS, Pred, Increasing))
7669 return false;
7670
7671 // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to
7672 // true as the loop iterates, and the backedge is control dependent on
7673 // "ArLHS `Pred` RHS" == true then we can reason as follows:
7674 //
7675 // * if the predicate was false in the first iteration then the predicate
7676 // is never evaluated again, since the loop exits without taking the
7677 // backedge.
7678 // * if the predicate was true in the first iteration then it will
7679 // continue to be true for all future iterations since it is
7680 // monotonically increasing.
7681 //
7682 // For both the above possibilities, we can replace the loop varying
7683 // predicate with its value on the first iteration of the loop (which is
7684 // loop invariant).
7685 //
7686 // A similar reasoning applies for a monotonically decreasing predicate, by
7687 // replacing true with false and false with true in the above two bullets.
7688
7689 auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred);
7690
7691 if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS))
7692 return false;
7693
7694 InvariantPred = Pred;
7695 InvariantLHS = ArLHS->getStart();
7696 InvariantRHS = RHS;
7697 return true;
7698}
7699
7700bool ScalarEvolution::isKnownPredicateViaConstantRanges(
7701 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
7702 if (HasSameValue(LHS, RHS))
7703 return ICmpInst::isTrueWhenEqual(Pred);
7704
7705 // This code is split out from isKnownPredicate because it is called from
7706 // within isLoopEntryGuardedByCond.
7707
7708 auto CheckRanges =
7709 [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) {
7710 return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS)
7711 .contains(RangeLHS);
7712 };
7713
7714 // The check at the top of the function catches the case where the values are
7715 // known to be equal.
7716 if (Pred == CmpInst::ICMP_EQ)
7717 return false;
7718
7719 if (Pred == CmpInst::ICMP_NE)
7720 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
7721 CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) ||
7722 isKnownNonZero(getMinusSCEV(LHS, RHS));
7723
7724 if (CmpInst::isSigned(Pred))
7725 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
7726
7727 return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
7728}
7729
7730bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
7731 const SCEV *LHS,
7732 const SCEV *RHS) {
7733
7734 // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer.
7735 // Return Y via OutY.
7736 auto MatchBinaryAddToConst =
7737 [this](const SCEV *Result, const SCEV *X, APInt &OutY,
7738 SCEV::NoWrapFlags ExpectedFlags) {
7739 const SCEV *NonConstOp, *ConstOp;
7740 SCEV::NoWrapFlags FlagsPresent;
7741
7742 if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) ||
7743 !isa<SCEVConstant>(ConstOp) || NonConstOp != X)
7744 return false;
7745
7746 OutY = cast<SCEVConstant>(ConstOp)->getAPInt();
7747 return (FlagsPresent & ExpectedFlags) == ExpectedFlags;
7748 };
7749
7750 APInt C;
7751
7752 switch (Pred) {
7753 default:
7754 break;
7755
7756 case ICmpInst::ICMP_SGE:
7757 std::swap(LHS, RHS);
7758 case ICmpInst::ICMP_SLE:
7759 // X s<= (X + C)<nsw> if C >= 0
7760 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative())
7761 return true;
7762
7763 // (X + C)<nsw> s<= X if C <= 0
7764 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) &&
7765 !C.isStrictlyPositive())
7766 return true;
7767 break;
7768
7769 case ICmpInst::ICMP_SGT:
7770 std::swap(LHS, RHS);
7771 case ICmpInst::ICMP_SLT:
7772 // X s< (X + C)<nsw> if C > 0
7773 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) &&
7774 C.isStrictlyPositive())
7775 return true;
7776
7777 // (X + C)<nsw> s< X if C < 0
7778 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative())
7779 return true;
7780 break;
7781 }
7782
7783 return false;
7784}
7785
7786bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
7787 const SCEV *LHS,
7788 const SCEV *RHS) {
7789 if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate)
7790 return false;
7791
7792 // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on
7793 // the stack can result in exponential time complexity.
7794 SaveAndRestore<bool> Restore(ProvingSplitPredicate, true);
7795
7796 // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L
7797 //
7798 // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use
7799 // isKnownPredicate. isKnownPredicate is more powerful, but also more
7800 // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
7801 // interesting cases seen in practice. We can consider "upgrading" L >= 0 to
7802 // use isKnownPredicate later if needed.
7803 return isKnownNonNegative(RHS) &&
7804 isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
7805 isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
7806}
7807
7808/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
7809/// protected by a conditional between LHS and RHS. This is used to
7810/// to eliminate casts.
7811bool
7812ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
7813 ICmpInst::Predicate Pred,
7814 const SCEV *LHS, const SCEV *RHS) {
7815 // Interpret a null as meaning no loop, where there is obviously no guard
7816 // (interprocedural conditions notwithstanding).
7817 if (!L) return true;
7818
7819 if (isKnownPredicateViaConstantRanges(Pred, LHS, RHS))
7820 return true;
7821
7822 BasicBlock *Latch = L->getLoopLatch();
7823 if (!Latch)
7824 return false;
7825
7826 BranchInst *LoopContinuePredicate =
7827 dyn_cast<BranchInst>(Latch->getTerminator());
7828 if (LoopContinuePredicate && LoopContinuePredicate->isConditional() &&
7829 isImpliedCond(Pred, LHS, RHS,
7830 LoopContinuePredicate->getCondition(),
7831 LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
7832 return true;
7833
7834 // We don't want more than one activation of the following loops on the stack
7835 // -- that can lead to O(n!) time complexity.
7836 if (WalkingBEDominatingConds)
7837 return false;
7838
7839 SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true);
7840
7841 // See if we can exploit a trip count to prove the predicate.
7842 const auto &BETakenInfo = getBackedgeTakenInfo(L);
7843 const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this);
7844 if (LatchBECount != getCouldNotCompute()) {
7845 // We know that Latch branches back to the loop header exactly
7846 // LatchBECount times. This means the backdege condition at Latch is
7847 // equivalent to "{0,+,1} u< LatchBECount".
7848 Type *Ty = LatchBECount->getType();
7849 auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW);
7850 const SCEV *LoopCounter =
7851 getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags);
7852 if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter,
7853 LatchBECount))
7854 return true;
7855 }
7856
7857 // Check conditions due to any @llvm.assume intrinsics.
7858 for (auto &AssumeVH : AC.assumptions()) {
7859 if (!AssumeVH)
7860 continue;
7861 auto *CI = cast<CallInst>(AssumeVH);
7862 if (!DT.dominates(CI, Latch->getTerminator()))
7863 continue;
7864
7865 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
7866 return true;
7867 }
7868
7869 // If the loop is not reachable from the entry block, we risk running into an
7870 // infinite loop as we walk up into the dom tree. These loops do not matter
7871 // anyway, so we just return a conservative answer when we see them.
7872 if (!DT.isReachableFromEntry(L->getHeader()))
7873 return false;
7874
7875 for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
7876 DTN != HeaderDTN; DTN = DTN->getIDom()) {
7877
7878 assert(DTN && "should reach the loop header before reaching the root!")((DTN && "should reach the loop header before reaching the root!"
) ? static_cast<void> (0) : __assert_fail ("DTN && \"should reach the loop header before reaching the root!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7878, __PRETTY_FUNCTION__));
7879
7880 BasicBlock *BB = DTN->getBlock();
7881 BasicBlock *PBB = BB->getSinglePredecessor();
7882 if (!PBB)
7883 continue;
7884
7885 BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
7886 if (!ContinuePredicate || !ContinuePredicate->isConditional())
7887 continue;
7888
7889 Value *Condition = ContinuePredicate->getCondition();
7890
7891 // If we have an edge `E` within the loop body that dominates the only
7892 // latch, the condition guarding `E` also guards the backedge. This
7893 // reasoning works only for loops with a single latch.
7894
7895 BasicBlockEdge DominatingEdge(PBB, BB);
7896 if (DominatingEdge.isSingleEdge()) {
7897 // We're constructively (and conservatively) enumerating edges within the
7898 // loop body that dominate the latch. The dominator tree better agree
7899 // with us on this:
7900 assert(DT.dominates(DominatingEdge, Latch) && "should be!")((DT.dominates(DominatingEdge, Latch) && "should be!"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates(DominatingEdge, Latch) && \"should be!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 7900, __PRETTY_FUNCTION__));
7901
7902 if (isImpliedCond(Pred, LHS, RHS, Condition,
7903 BB != ContinuePredicate->getSuccessor(0)))
7904 return true;
7905 }
7906 }
7907
7908 return false;
7909}
7910
7911/// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
7912/// by a conditional between LHS and RHS. This is used to help avoid max
7913/// expressions in loop trip counts, and to eliminate casts.
7914bool
7915ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
7916 ICmpInst::Predicate Pred,
7917 const SCEV *LHS, const SCEV *RHS) {
7918 // Interpret a null as meaning no loop, where there is obviously no guard
7919 // (interprocedural conditions notwithstanding).
7920 if (!L) return false;
7921
7922 if (isKnownPredicateViaConstantRanges(Pred, LHS, RHS))
7923 return true;
7924
7925 // Starting at the loop predecessor, climb up the predecessor chain, as long
7926 // as there are predecessors that can be found that have unique successors
7927 // leading to the original header.
7928 for (std::pair<BasicBlock *, BasicBlock *>
7929 Pair(L->getLoopPredecessor(), L->getHeader());
7930 Pair.first;
7931 Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
7932
7933 BranchInst *LoopEntryPredicate =
7934 dyn_cast<BranchInst>(Pair.first->getTerminator());
7935 if (!LoopEntryPredicate ||
7936 LoopEntryPredicate->isUnconditional())
7937 continue;
7938
7939 if (isImpliedCond(Pred, LHS, RHS,
7940 LoopEntryPredicate->getCondition(),
7941 LoopEntryPredicate->getSuccessor(0) != Pair.second))
7942 return true;
7943 }
7944
7945 // Check conditions due to any @llvm.assume intrinsics.
7946 for (auto &AssumeVH : AC.assumptions()) {
7947 if (!AssumeVH)
7948 continue;
7949 auto *CI = cast<CallInst>(AssumeVH);
7950 if (!DT.dominates(CI, L->getHeader()))
7951 continue;
7952
7953 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
7954 return true;
7955 }
7956
7957 return false;
7958}
7959
7960namespace {
7961/// RAII wrapper to prevent recursive application of isImpliedCond.
7962/// ScalarEvolution's PendingLoopPredicates set must be empty unless we are
7963/// currently evaluating isImpliedCond.
7964struct MarkPendingLoopPredicate {
7965 Value *Cond;
7966 DenseSet<Value*> &LoopPreds;
7967 bool Pending;
7968
7969 MarkPendingLoopPredicate(Value *C, DenseSet<Value*> &LP)
7970 : Cond(C), LoopPreds(LP) {
7971 Pending = !LoopPreds.insert(Cond).second;
7972 }
7973 ~MarkPendingLoopPredicate() {
7974 if (!Pending)
7975 LoopPreds.erase(Cond);
7976 }
7977};
7978} // end anonymous namespace
7979
7980/// isImpliedCond - Test whether the condition described by Pred, LHS,
7981/// and RHS is true whenever the given Cond value evaluates to true.
7982bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
7983 const SCEV *LHS, const SCEV *RHS,
7984 Value *FoundCondValue,
7985 bool Inverse) {
7986 MarkPendingLoopPredicate Mark(FoundCondValue, PendingLoopPredicates);
7987 if (Mark.Pending)
7988 return false;
7989
7990 // Recursively handle And and Or conditions.
7991 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) {
7992 if (BO->getOpcode() == Instruction::And) {
7993 if (!Inverse)
7994 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
7995 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
7996 } else if (BO->getOpcode() == Instruction::Or) {
7997 if (Inverse)
7998 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
7999 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
8000 }
8001 }
8002
8003 ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
8004 if (!ICI) return false;
8005
8006 // Now that we found a conditional branch that dominates the loop or controls
8007 // the loop latch. Check to see if it is the comparison we are looking for.
8008 ICmpInst::Predicate FoundPred;
8009 if (Inverse)
8010 FoundPred = ICI->getInversePredicate();
8011 else
8012 FoundPred = ICI->getPredicate();
8013
8014 const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
8015 const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
8016
8017 return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS);
8018}
8019
8020bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
8021 const SCEV *RHS,
8022 ICmpInst::Predicate FoundPred,
8023 const SCEV *FoundLHS,
8024 const SCEV *FoundRHS) {
8025 // Balance the types.
8026 if (getTypeSizeInBits(LHS->getType()) <
8027 getTypeSizeInBits(FoundLHS->getType())) {
8028 if (CmpInst::isSigned(Pred)) {
8029 LHS = getSignExtendExpr(LHS, FoundLHS->getType());
8030 RHS = getSignExtendExpr(RHS, FoundLHS->getType());
8031 } else {
8032 LHS = getZeroExtendExpr(LHS, FoundLHS->getType());
8033 RHS = getZeroExtendExpr(RHS, FoundLHS->getType());
8034 }
8035 } else if (getTypeSizeInBits(LHS->getType()) >
8036 getTypeSizeInBits(FoundLHS->getType())) {
8037 if (CmpInst::isSigned(FoundPred)) {
8038 FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
8039 FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
8040 } else {
8041 FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
8042 FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
8043 }
8044 }
8045
8046 // Canonicalize the query to match the way instcombine will have
8047 // canonicalized the comparison.
8048 if (SimplifyICmpOperands(Pred, LHS, RHS))
8049 if (LHS == RHS)
8050 return CmpInst::isTrueWhenEqual(Pred);
8051 if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
8052 if (FoundLHS == FoundRHS)
8053 return CmpInst::isFalseWhenEqual(FoundPred);
8054
8055 // Check to see if we can make the LHS or RHS match.
8056 if (LHS == FoundRHS || RHS == FoundLHS) {
8057 if (isa<SCEVConstant>(RHS)) {
8058 std::swap(FoundLHS, FoundRHS);
8059 FoundPred = ICmpInst::getSwappedPredicate(FoundPred);
8060 } else {
8061 std::swap(LHS, RHS);
8062 Pred = ICmpInst::getSwappedPredicate(Pred);
8063 }
8064 }
8065
8066 // Check whether the found predicate is the same as the desired predicate.
8067 if (FoundPred == Pred)
8068 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
8069
8070 // Check whether swapping the found predicate makes it the same as the
8071 // desired predicate.
8072 if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) {
8073 if (isa<SCEVConstant>(RHS))
8074 return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS);
8075 else
8076 return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred),
8077 RHS, LHS, FoundLHS, FoundRHS);
8078 }
8079
8080 // Unsigned comparison is the same as signed comparison when both the operands
8081 // are non-negative.
8082 if (CmpInst::isUnsigned(FoundPred) &&
8083 CmpInst::getSignedPredicate(FoundPred) == Pred &&
8084 isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS))
8085 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
8086
8087 // Check if we can make progress by sharpening ranges.
8088 if (FoundPred == ICmpInst::ICMP_NE &&
8089 (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) {
8090
8091 const SCEVConstant *C = nullptr;
8092 const SCEV *V = nullptr;
8093
8094 if (isa<SCEVConstant>(FoundLHS)) {
8095 C = cast<SCEVConstant>(FoundLHS);
8096 V = FoundRHS;
8097 } else {
8098 C = cast<SCEVConstant>(FoundRHS);
8099 V = FoundLHS;
8100 }
8101
8102 // The guarding predicate tells us that C != V. If the known range
8103 // of V is [C, t), we can sharpen the range to [C + 1, t). The
8104 // range we consider has to correspond to same signedness as the
8105 // predicate we're interested in folding.
8106
8107 APInt Min = ICmpInst::isSigned(Pred) ?
8108 getSignedRange(V).getSignedMin() : getUnsignedRange(V).getUnsignedMin();
8109
8110 if (Min == C->getAPInt()) {
8111 // Given (V >= Min && V != Min) we conclude V >= (Min + 1).
8112 // This is true even if (Min + 1) wraps around -- in case of
8113 // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)).
8114
8115 APInt SharperMin = Min + 1;
8116
8117 switch (Pred) {
8118 case ICmpInst::ICMP_SGE:
8119 case ICmpInst::ICMP_UGE:
8120 // We know V `Pred` SharperMin. If this implies LHS `Pred`
8121 // RHS, we're done.
8122 if (isImpliedCondOperands(Pred, LHS, RHS, V,
8123 getConstant(SharperMin)))
8124 return true;
8125
8126 case ICmpInst::ICMP_SGT:
8127 case ICmpInst::ICMP_UGT:
8128 // We know from the range information that (V `Pred` Min ||
8129 // V == Min). We know from the guarding condition that !(V
8130 // == Min). This gives us
8131 //
8132 // V `Pred` Min || V == Min && !(V == Min)
8133 // => V `Pred` Min
8134 //
8135 // If V `Pred` Min implies LHS `Pred` RHS, we're done.
8136
8137 if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min)))
8138 return true;
8139
8140 default:
8141 // No change
8142 break;
8143 }
8144 }
8145 }
8146
8147 // Check whether the actual condition is beyond sufficient.
8148 if (FoundPred == ICmpInst::ICMP_EQ)
8149 if (ICmpInst::isTrueWhenEqual(Pred))
8150 if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS))
8151 return true;
8152 if (Pred == ICmpInst::ICMP_NE)
8153 if (!ICmpInst::isTrueWhenEqual(FoundPred))
8154 if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS))
8155 return true;
8156
8157 // Otherwise assume the worst.
8158 return false;
8159}
8160
8161bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
8162 const SCEV *&L, const SCEV *&R,
8163 SCEV::NoWrapFlags &Flags) {
8164 const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
8165 if (!AE || AE->getNumOperands() != 2)
8166 return false;
8167
8168 L = AE->getOperand(0);
8169 R = AE->getOperand(1);
8170 Flags = AE->getNoWrapFlags();
8171 return true;
8172}
8173
8174bool ScalarEvolution::computeConstantDifference(const SCEV *Less,
8175 const SCEV *More,
8176 APInt &C) {
8177 // We avoid subtracting expressions here because this function is usually
8178 // fairly deep in the call stack (i.e. is called many times).
8179
8180 if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) {
8181 const auto *LAR = cast<SCEVAddRecExpr>(Less);
8182 const auto *MAR = cast<SCEVAddRecExpr>(More);
8183
8184 if (LAR->getLoop() != MAR->getLoop())
8185 return false;
8186
8187 // We look at affine expressions only; not for correctness but to keep
8188 // getStepRecurrence cheap.
8189 if (!LAR->isAffine() || !MAR->isAffine())
8190 return false;
8191
8192 if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this))
8193 return false;
8194
8195 Less = LAR->getStart();
8196 More = MAR->getStart();
8197
8198 // fall through
8199 }
8200
8201 if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) {
8202 const auto &M = cast<SCEVConstant>(More)->getAPInt();
8203 const auto &L = cast<SCEVConstant>(Less)->getAPInt();
8204 C = M - L;
8205 return true;
8206 }
8207
8208 const SCEV *L, *R;
8209 SCEV::NoWrapFlags Flags;
8210 if (splitBinaryAdd(Less, L, R, Flags))
8211 if (const auto *LC = dyn_cast<SCEVConstant>(L))
8212 if (R == More) {
8213 C = -(LC->getAPInt());
8214 return true;
8215 }
8216
8217 if (splitBinaryAdd(More, L, R, Flags))
8218 if (const auto *LC = dyn_cast<SCEVConstant>(L))
8219 if (R == Less) {
8220 C = LC->getAPInt();
8221 return true;
8222 }
8223
8224 return false;
8225}
8226
8227bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow(
8228 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
8229 const SCEV *FoundLHS, const SCEV *FoundRHS) {
8230 if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT)
8231 return false;
8232
8233 const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS);
8234 if (!AddRecLHS)
8235 return false;
8236
8237 const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS);
8238 if (!AddRecFoundLHS)
8239 return false;
8240
8241 // We'd like to let SCEV reason about control dependencies, so we constrain
8242 // both the inequalities to be about add recurrences on the same loop. This
8243 // way we can use isLoopEntryGuardedByCond later.
8244
8245 const Loop *L = AddRecFoundLHS->getLoop();
8246 if (L != AddRecLHS->getLoop())
8247 return false;
8248
8249 // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1)
8250 //
8251 // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C)
8252 // ... (2)
8253 //
8254 // Informal proof for (2), assuming (1) [*]:
8255 //
8256 // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**]
8257 //
8258 // Then
8259 //
8260 // FoundLHS s< FoundRHS s< INT_MIN - C
8261 // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ]
8262 // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ]
8263 // <=> (FoundLHS + INT_MIN + C + INT_MIN) s<
8264 // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ]
8265 // <=> FoundLHS + C s< FoundRHS + C
8266 //
8267 // [*]: (1) can be proved by ruling out overflow.
8268 //
8269 // [**]: This can be proved by analyzing all the four possibilities:
8270 // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and
8271 // (A s>= 0, B s>= 0).
8272 //
8273 // Note:
8274 // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C"
8275 // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS
8276 // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS
8277 // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is
8278 // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS +
8279 // C)".
8280
8281 APInt LDiff, RDiff;
8282 if (!computeConstantDifference(FoundLHS, LHS, LDiff) ||
8283 !computeConstantDifference(FoundRHS, RHS, RDiff) ||
8284 LDiff != RDiff)
8285 return false;
8286
8287 if (LDiff == 0)
8288 return true;
8289
8290 APInt FoundRHSLimit;
8291
8292 if (Pred == CmpInst::ICMP_ULT) {
8293 FoundRHSLimit = -RDiff;
8294 } else {
8295 assert(Pred == CmpInst::ICMP_SLT && "Checked above!")((Pred == CmpInst::ICMP_SLT && "Checked above!") ? static_cast
<void> (0) : __assert_fail ("Pred == CmpInst::ICMP_SLT && \"Checked above!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8295, __PRETTY_FUNCTION__));
8296 FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - RDiff;
8297 }
8298
8299 // Try to prove (1) or (2), as needed.
8300 return isLoopEntryGuardedByCond(L, Pred, FoundRHS,
8301 getConstant(FoundRHSLimit));
8302}
8303
8304/// isImpliedCondOperands - Test whether the condition described by Pred,
8305/// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
8306/// and FoundRHS is true.
8307bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
8308 const SCEV *LHS, const SCEV *RHS,
8309 const SCEV *FoundLHS,
8310 const SCEV *FoundRHS) {
8311 if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS))
8312 return true;
8313
8314 if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS))
8315 return true;
8316
8317 return isImpliedCondOperandsHelper(Pred, LHS, RHS,
8318 FoundLHS, FoundRHS) ||
8319 // ~x < ~y --> x > y
8320 isImpliedCondOperandsHelper(Pred, LHS, RHS,
8321 getNotSCEV(FoundRHS),
8322 getNotSCEV(FoundLHS));
8323}
8324
8325
8326/// If Expr computes ~A, return A else return nullptr
8327static const SCEV *MatchNotExpr(const SCEV *Expr) {
8328 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
8329 if (!Add || Add->getNumOperands() != 2 ||
8330 !Add->getOperand(0)->isAllOnesValue())
8331 return nullptr;
8332
8333 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
8334 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
8335 !AddRHS->getOperand(0)->isAllOnesValue())
8336 return nullptr;
8337
8338 return AddRHS->getOperand(1);
8339}
8340
8341
8342/// Is MaybeMaxExpr an SMax or UMax of Candidate and some other values?
8343template<typename MaxExprType>
8344static bool IsMaxConsistingOf(const SCEV *MaybeMaxExpr,
8345 const SCEV *Candidate) {
8346 const MaxExprType *MaxExpr = dyn_cast<MaxExprType>(MaybeMaxExpr);
8347 if (!MaxExpr) return false;
8348
8349 return find(MaxExpr->operands(), Candidate) != MaxExpr->op_end();
8350}
8351
8352
8353/// Is MaybeMinExpr an SMin or UMin of Candidate and some other values?
8354template<typename MaxExprType>
8355static bool IsMinConsistingOf(ScalarEvolution &SE,
8356 const SCEV *MaybeMinExpr,
8357 const SCEV *Candidate) {
8358 const SCEV *MaybeMaxExpr = MatchNotExpr(MaybeMinExpr);
8359 if (!MaybeMaxExpr)
8360 return false;
8361
8362 return IsMaxConsistingOf<MaxExprType>(MaybeMaxExpr, SE.getNotSCEV(Candidate));
8363}
8364
8365static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE,
8366 ICmpInst::Predicate Pred,
8367 const SCEV *LHS, const SCEV *RHS) {
8368
8369 // If both sides are affine addrecs for the same loop, with equal
8370 // steps, and we know the recurrences don't wrap, then we only
8371 // need to check the predicate on the starting values.
8372
8373 if (!ICmpInst::isRelational(Pred))
8374 return false;
8375
8376 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
8377 if (!LAR)
8378 return false;
8379 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
8380 if (!RAR)
8381 return false;
8382 if (LAR->getLoop() != RAR->getLoop())
8383 return false;
8384 if (!LAR->isAffine() || !RAR->isAffine())
8385 return false;
8386
8387 if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE))
8388 return false;
8389
8390 SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ?
8391 SCEV::FlagNSW : SCEV::FlagNUW;
8392 if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW))
8393 return false;
8394
8395 return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart());
8396}
8397
8398/// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max
8399/// expression?
8400static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
8401 ICmpInst::Predicate Pred,
8402 const SCEV *LHS, const SCEV *RHS) {
8403 switch (Pred) {
8404 default:
8405 return false;
8406
8407 case ICmpInst::ICMP_SGE:
8408 std::swap(LHS, RHS);
8409 // fall through
8410 case ICmpInst::ICMP_SLE:
8411 return
8412 // min(A, ...) <= A
8413 IsMinConsistingOf<SCEVSMaxExpr>(SE, LHS, RHS) ||
8414 // A <= max(A, ...)
8415 IsMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS);
8416
8417 case ICmpInst::ICMP_UGE:
8418 std::swap(LHS, RHS);
8419 // fall through
8420 case ICmpInst::ICMP_ULE:
8421 return
8422 // min(A, ...) <= A
8423 IsMinConsistingOf<SCEVUMaxExpr>(SE, LHS, RHS) ||
8424 // A <= max(A, ...)
8425 IsMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS);
8426 }
8427
8428 llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8428);
8429}
8430
8431/// isImpliedCondOperandsHelper - Test whether the condition described by
8432/// Pred, LHS, and RHS is true whenever the condition described by Pred,
8433/// FoundLHS, and FoundRHS is true.
8434bool
8435ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
8436 const SCEV *LHS, const SCEV *RHS,
8437 const SCEV *FoundLHS,
8438 const SCEV *FoundRHS) {
8439 auto IsKnownPredicateFull =
8440 [this](ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
8441 return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
8442 IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
8443 IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
8444 isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
8445 };
8446
8447 switch (Pred) {
8448 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8448);
8449 case ICmpInst::ICMP_EQ:
8450 case ICmpInst::ICMP_NE:
8451 if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
8452 return true;
8453 break;
8454 case ICmpInst::ICMP_SLT:
8455 case ICmpInst::ICMP_SLE:
8456 if (IsKnownPredicateFull(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
8457 IsKnownPredicateFull(ICmpInst::ICMP_SGE, RHS, FoundRHS))
8458 return true;
8459 break;
8460 case ICmpInst::ICMP_SGT:
8461 case ICmpInst::ICMP_SGE:
8462 if (IsKnownPredicateFull(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
8463 IsKnownPredicateFull(ICmpInst::ICMP_SLE, RHS, FoundRHS))
8464 return true;
8465 break;
8466 case ICmpInst::ICMP_ULT:
8467 case ICmpInst::ICMP_ULE:
8468 if (IsKnownPredicateFull(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
8469 IsKnownPredicateFull(ICmpInst::ICMP_UGE, RHS, FoundRHS))
8470 return true;
8471 break;
8472 case ICmpInst::ICMP_UGT:
8473 case ICmpInst::ICMP_UGE:
8474 if (IsKnownPredicateFull(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
8475 IsKnownPredicateFull(ICmpInst::ICMP_ULE, RHS, FoundRHS))
8476 return true;
8477 break;
8478 }
8479
8480 return false;
8481}
8482
8483/// isImpliedCondOperandsViaRanges - helper function for isImpliedCondOperands.
8484/// Tries to get cases like "X `sgt` 0 => X - 1 `sgt` -1".
8485bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
8486 const SCEV *LHS,
8487 const SCEV *RHS,
8488 const SCEV *FoundLHS,
8489 const SCEV *FoundRHS) {
8490 if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS))
8491 // The restriction on `FoundRHS` be lifted easily -- it exists only to
8492 // reduce the compile time impact of this optimization.
8493 return false;
8494
8495 const SCEVAddExpr *AddLHS = dyn_cast<SCEVAddExpr>(LHS);
8496 if (!AddLHS || AddLHS->getOperand(1) != FoundLHS ||
8497 !isa<SCEVConstant>(AddLHS->getOperand(0)))
8498 return false;
8499
8500 APInt ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt();
8501
8502 // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the
8503 // antecedent "`FoundLHS` `Pred` `FoundRHS`".
8504 ConstantRange FoundLHSRange =
8505 ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS);
8506
8507 // Since `LHS` is `FoundLHS` + `AddLHS->getOperand(0)`, we can compute a range
8508 // for `LHS`:
8509 APInt Addend = cast<SCEVConstant>(AddLHS->getOperand(0))->getAPInt();
8510 ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(Addend));
8511
8512 // We can also compute the range of values for `LHS` that satisfy the
8513 // consequent, "`LHS` `Pred` `RHS`":
8514 APInt ConstRHS = cast<SCEVConstant>(RHS)->getAPInt();
8515 ConstantRange SatisfyingLHSRange =
8516 ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS);
8517
8518 // The antecedent implies the consequent if every value of `LHS` that
8519 // satisfies the antecedent also satisfies the consequent.
8520 return SatisfyingLHSRange.contains(LHSRange);
8521}
8522
8523// Verify if an linear IV with positive stride can overflow when in a
8524// less-than comparison, knowing the invariant term of the comparison, the
8525// stride and the knowledge of NSW/NUW flags on the recurrence.
8526bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
8527 bool IsSigned, bool NoWrap) {
8528 if (NoWrap) return false;
8529
8530 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
8531 const SCEV *One = getOne(Stride->getType());
8532
8533 if (IsSigned) {
8534 APInt MaxRHS = getSignedRange(RHS).getSignedMax();
8535 APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
8536 APInt MaxStrideMinusOne = getSignedRange(getMinusSCEV(Stride, One))
8537 .getSignedMax();
8538
8539 // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow!
8540 return (MaxValue - MaxStrideMinusOne).slt(MaxRHS);
8541 }
8542
8543 APInt MaxRHS = getUnsignedRange(RHS).getUnsignedMax();
8544 APInt MaxValue = APInt::getMaxValue(BitWidth);
8545 APInt MaxStrideMinusOne = getUnsignedRange(getMinusSCEV(Stride, One))
8546 .getUnsignedMax();
8547
8548 // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow!
8549 return (MaxValue - MaxStrideMinusOne).ult(MaxRHS);
8550}
8551
8552// Verify if an linear IV with negative stride can overflow when in a
8553// greater-than comparison, knowing the invariant term of the comparison,
8554// the stride and the knowledge of NSW/NUW flags on the recurrence.
8555bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
8556 bool IsSigned, bool NoWrap) {
8557 if (NoWrap) return false;
8558
8559 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
8560 const SCEV *One = getOne(Stride->getType());
8561
8562 if (IsSigned) {
8563 APInt MinRHS = getSignedRange(RHS).getSignedMin();
8564 APInt MinValue = APInt::getSignedMinValue(BitWidth);
8565 APInt MaxStrideMinusOne = getSignedRange(getMinusSCEV(Stride, One))
8566 .getSignedMax();
8567
8568 // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow!
8569 return (MinValue + MaxStrideMinusOne).sgt(MinRHS);
8570 }
8571
8572 APInt MinRHS = getUnsignedRange(RHS).getUnsignedMin();
8573 APInt MinValue = APInt::getMinValue(BitWidth);
8574 APInt MaxStrideMinusOne = getUnsignedRange(getMinusSCEV(Stride, One))
8575 .getUnsignedMax();
8576
8577 // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow!
8578 return (MinValue + MaxStrideMinusOne).ugt(MinRHS);
8579}
8580
8581// Compute the backedge taken count knowing the interval difference, the
8582// stride and presence of the equality in the comparison.
8583const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step,
8584 bool Equality) {
8585 const SCEV *One = getOne(Step->getType());
8586 Delta = Equality ? getAddExpr(Delta, Step)
8587 : getAddExpr(Delta, getMinusSCEV(Step, One));
8588 return getUDivExpr(Delta, Step);
8589}
8590
8591/// HowManyLessThans - Return the number of times a backedge containing the
8592/// specified less-than comparison will execute. If not computable, return
8593/// CouldNotCompute.
8594///
8595/// @param ControlsExit is true when the LHS < RHS condition directly controls
8596/// the branch (loops exits only if condition is true). In this case, we can use
8597/// NoWrapFlags to skip overflow checks.
8598ScalarEvolution::ExitLimit
8599ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
8600 const Loop *L, bool IsSigned,
8601 bool ControlsExit, bool AllowPredicates) {
8602 SCEVUnionPredicate P;
8603 // We handle only IV < Invariant
8604 if (!isLoopInvariant(RHS, L))
8605 return getCouldNotCompute();
8606
8607 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
8608 if (!IV && AllowPredicates)
8609 // Try to make this an AddRec using runtime tests, in the first X
8610 // iterations of this loop, where X is the SCEV expression found by the
8611 // algorithm below.
8612 IV = convertSCEVToAddRecWithPredicates(LHS, L, P);
8613
8614 // Avoid weird loops
8615 if (!IV || IV->getLoop() != L || !IV->isAffine())
8616 return getCouldNotCompute();
8617
8618 bool NoWrap = ControlsExit &&
8619 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
8620
8621 const SCEV *Stride = IV->getStepRecurrence(*this);
8622
8623 // Avoid negative or zero stride values
8624 if (!isKnownPositive(Stride))
8625 return getCouldNotCompute();
8626
8627 // Avoid proven overflow cases: this will ensure that the backedge taken count
8628 // will not generate any unsigned overflow. Relaxed no-overflow conditions
8629 // exploit NoWrapFlags, allowing to optimize in presence of undefined
8630 // behaviors like the case of C language.
8631 if (!Stride->isOne() && doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap))
8632 return getCouldNotCompute();
8633
8634 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT
8635 : ICmpInst::ICMP_ULT;
8636 const SCEV *Start = IV->getStart();
8637 const SCEV *End = RHS;
8638 if (!isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS)) {
8639 const SCEV *Diff = getMinusSCEV(RHS, Start);
8640 // If we have NoWrap set, then we can assume that the increment won't
8641 // overflow, in which case if RHS - Start is a constant, we don't need to
8642 // do a max operation since we can just figure it out statically
8643 if (NoWrap && isa<SCEVConstant>(Diff)) {
8644 APInt D = dyn_cast<const SCEVConstant>(Diff)->getAPInt();
8645 if (D.isNegative())
8646 End = Start;
8647 } else
8648 End = IsSigned ? getSMaxExpr(RHS, Start)
8649 : getUMaxExpr(RHS, Start);
8650 }
8651
8652 const SCEV *BECount = computeBECount(getMinusSCEV(End, Start), Stride, false);
8653
8654 APInt MinStart = IsSigned ? getSignedRange(Start).getSignedMin()
8655 : getUnsignedRange(Start).getUnsignedMin();
8656
8657 APInt MinStride = IsSigned ? getSignedRange(Stride).getSignedMin()
8658 : getUnsignedRange(Stride).getUnsignedMin();
8659
8660 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
8661 APInt Limit = IsSigned ? APInt::getSignedMaxValue(BitWidth) - (MinStride - 1)
8662 : APInt::getMaxValue(BitWidth) - (MinStride - 1);
8663
8664 // Although End can be a MAX expression we estimate MaxEnd considering only
8665 // the case End = RHS. This is safe because in the other case (End - Start)
8666 // is zero, leading to a zero maximum backedge taken count.
8667 APInt MaxEnd =
8668 IsSigned ? APIntOps::smin(getSignedRange(RHS).getSignedMax(), Limit)
8669 : APIntOps::umin(getUnsignedRange(RHS).getUnsignedMax(), Limit);
8670
8671 const SCEV *MaxBECount;
8672 if (isa<SCEVConstant>(BECount))
8673 MaxBECount = BECount;
8674 else
8675 MaxBECount = computeBECount(getConstant(MaxEnd - MinStart),
8676 getConstant(MinStride), false);
8677
8678 if (isa<SCEVCouldNotCompute>(MaxBECount))
8679 MaxBECount = BECount;
8680
8681 return ExitLimit(BECount, MaxBECount, P);
8682}
8683
8684ScalarEvolution::ExitLimit
8685ScalarEvolution::HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
8686 const Loop *L, bool IsSigned,
8687 bool ControlsExit, bool AllowPredicates) {
8688 SCEVUnionPredicate P;
8689 // We handle only IV > Invariant
8690 if (!isLoopInvariant(RHS, L))
8691 return getCouldNotCompute();
8692
8693 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
8694 if (!IV && AllowPredicates)
8695 // Try to make this an AddRec using runtime tests, in the first X
8696 // iterations of this loop, where X is the SCEV expression found by the
8697 // algorithm below.
8698 IV = convertSCEVToAddRecWithPredicates(LHS, L, P);
8699
8700 // Avoid weird loops
8701 if (!IV || IV->getLoop() != L || !IV->isAffine())
8702 return getCouldNotCompute();
8703
8704 bool NoWrap = ControlsExit &&
8705 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
8706
8707 const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this));
8708
8709 // Avoid negative or zero stride values
8710 if (!isKnownPositive(Stride))
8711 return getCouldNotCompute();
8712
8713 // Avoid proven overflow cases: this will ensure that the backedge taken count
8714 // will not generate any unsigned overflow. Relaxed no-overflow conditions
8715 // exploit NoWrapFlags, allowing to optimize in presence of undefined
8716 // behaviors like the case of C language.
8717 if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap))
8718 return getCouldNotCompute();
8719
8720 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT
8721 : ICmpInst::ICMP_UGT;
8722
8723 const SCEV *Start = IV->getStart();
8724 const SCEV *End = RHS;
8725 if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) {
8726 const SCEV *Diff = getMinusSCEV(RHS, Start);
8727 // If we have NoWrap set, then we can assume that the increment won't
8728 // overflow, in which case if RHS - Start is a constant, we don't need to
8729 // do a max operation since we can just figure it out statically
8730 if (NoWrap && isa<SCEVConstant>(Diff)) {
8731 APInt D = dyn_cast<const SCEVConstant>(Diff)->getAPInt();
8732 if (!D.isNegative())
8733 End = Start;
8734 } else
8735 End = IsSigned ? getSMinExpr(RHS, Start)
8736 : getUMinExpr(RHS, Start);
8737 }
8738
8739 const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
8740
8741 APInt MaxStart = IsSigned ? getSignedRange(Start).getSignedMax()
8742 : getUnsignedRange(Start).getUnsignedMax();
8743
8744 APInt MinStride = IsSigned ? getSignedRange(Stride).getSignedMin()
8745 : getUnsignedRange(Stride).getUnsignedMin();
8746
8747 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
8748 APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1)
8749 : APInt::getMinValue(BitWidth) + (MinStride - 1);
8750
8751 // Although End can be a MIN expression we estimate MinEnd considering only
8752 // the case End = RHS. This is safe because in the other case (Start - End)
8753 // is zero, leading to a zero maximum backedge taken count.
8754 APInt MinEnd =
8755 IsSigned ? APIntOps::smax(getSignedRange(RHS).getSignedMin(), Limit)
8756 : APIntOps::umax(getUnsignedRange(RHS).getUnsignedMin(), Limit);
8757
8758
8759 const SCEV *MaxBECount = getCouldNotCompute();
8760 if (isa<SCEVConstant>(BECount))
8761 MaxBECount = BECount;
8762 else
8763 MaxBECount = computeBECount(getConstant(MaxStart - MinEnd),
8764 getConstant(MinStride), false);
8765
8766 if (isa<SCEVCouldNotCompute>(MaxBECount))
8767 MaxBECount = BECount;
8768
8769 return ExitLimit(BECount, MaxBECount, P);
8770}
8771
8772/// getNumIterationsInRange - Return the number of iterations of this loop that
8773/// produce values in the specified constant range. Another way of looking at
8774/// this is that it returns the first iteration number where the value is not in
8775/// the condition, thus computing the exit count. If the iteration count can't
8776/// be computed, an instance of SCEVCouldNotCompute is returned.
8777const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range,
8778 ScalarEvolution &SE) const {
8779 if (Range.isFullSet()) // Infinite loop.
8780 return SE.getCouldNotCompute();
8781
8782 // If the start is a non-zero constant, shift the range to simplify things.
8783 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
8784 if (!SC->getValue()->isZero()) {
8785 SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
8786 Operands[0] = SE.getZero(SC->getType());
8787 const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
8788 getNoWrapFlags(FlagNW));
8789 if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
8790 return ShiftedAddRec->getNumIterationsInRange(
8791 Range.subtract(SC->getAPInt()), SE);
8792 // This is strange and shouldn't happen.
8793 return SE.getCouldNotCompute();
8794 }
8795
8796 // The only time we can solve this is when we have all constant indices.
8797 // Otherwise, we cannot determine the overflow conditions.
8798 if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); }))
8799 return SE.getCouldNotCompute();
8800
8801 // Okay at this point we know that all elements of the chrec are constants and
8802 // that the start element is zero.
8803
8804 // First check to see if the range contains zero. If not, the first
8805 // iteration exits.
8806 unsigned BitWidth = SE.getTypeSizeInBits(getType());
8807 if (!Range.contains(APInt(BitWidth, 0)))
8808 return SE.getZero(getType());
8809
8810 if (isAffine()) {
8811 // If this is an affine expression then we have this situation:
8812 // Solve {0,+,A} in Range === Ax in Range
8813
8814 // We know that zero is in the range. If A is positive then we know that
8815 // the upper value of the range must be the first possible exit value.
8816 // If A is negative then the lower of the range is the last possible loop
8817 // value. Also note that we already checked for a full range.
8818 APInt One(BitWidth,1);
8819 APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt();
8820 APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower();
8821
8822 // The exit value should be (End+A)/A.
8823 APInt ExitVal = (End + A).udiv(A);
8824 ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
8825
8826 // Evaluate at the exit value. If we really did fall out of the valid
8827 // range, then we computed our trip count, otherwise wrap around or other
8828 // things must have happened.
8829 ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
8830 if (Range.contains(Val->getValue()))
8831 return SE.getCouldNotCompute(); // Something strange happened
8832
8833 // Ensure that the previous value is in the range. This is a sanity check.
8834 assert(Range.contains(((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8837, __PRETTY_FUNCTION__))
8835 EvaluateConstantChrecAtConstant(this,((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8837, __PRETTY_FUNCTION__))
8836 ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8837, __PRETTY_FUNCTION__))
8837 "Linear scev computation is off in a bad way!")((Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt
::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&
"Linear scev computation is off in a bad way!") ? static_cast
<void> (0) : __assert_fail ("Range.contains( EvaluateConstantChrecAtConstant(this, ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) && \"Linear scev computation is off in a bad way!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 8837, __PRETTY_FUNCTION__));
8838 return SE.getConstant(ExitValue);
8839 } else if (isQuadratic()) {
8840 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of the
8841 // quadratic equation to solve it. To do this, we must frame our problem in
8842 // terms of figuring out when zero is crossed, instead of when
8843 // Range.getUpper() is crossed.
8844 SmallVector<const SCEV *, 4> NewOps(op_begin(), op_end());
8845 NewOps[0] = SE.getNegativeSCEV(SE.getConstant(Range.getUpper()));
8846 const SCEV *NewAddRec = SE.getAddRecExpr(NewOps, getLoop(),
8847 // getNoWrapFlags(FlagNW)
8848 FlagAnyWrap);
8849
8850 // Next, solve the constructed addrec
8851 auto Roots = SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE);
8852 const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
8853 const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
8854 if (R1) {
8855 // Pick the smallest positive root value.
8856 if (ConstantInt *CB = dyn_cast<ConstantInt>(ConstantExpr::getICmp(
8857 ICmpInst::ICMP_ULT, R1->getValue(), R2->getValue()))) {
8858 if (!CB->getZExtValue())
8859 std::swap(R1, R2); // R1 is the minimum root now.
8860
8861 // Make sure the root is not off by one. The returned iteration should
8862 // not be in the range, but the previous one should be. When solving
8863 // for "X*X < 5", for example, we should not return a root of 2.
8864 ConstantInt *R1Val = EvaluateConstantChrecAtConstant(this,
8865 R1->getValue(),
8866 SE);
8867 if (Range.contains(R1Val->getValue())) {
8868 // The next iteration must be out of the range...
8869 ConstantInt *NextVal =
8870 ConstantInt::get(SE.getContext(), R1->getAPInt() + 1);
8871
8872 R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
8873 if (!Range.contains(R1Val->getValue()))
8874 return SE.getConstant(NextVal);
8875 return SE.getCouldNotCompute(); // Something strange happened
8876 }
8877
8878 // If R1 was not in the range, then it is a good return value. Make
8879 // sure that R1-1 WAS in the range though, just in case.
8880 ConstantInt *NextVal =
8881 ConstantInt::get(SE.getContext(), R1->getAPInt() - 1);
8882 R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
8883 if (Range.contains(R1Val->getValue()))
8884 return R1;
8885 return SE.getCouldNotCompute(); // Something strange happened
8886 }
8887 }
8888 }
8889
8890 return SE.getCouldNotCompute();
8891}
8892
8893namespace {
8894struct FindUndefs {
8895 bool Found;
8896 FindUndefs() : Found(false) {}
8897
8898 bool follow(const SCEV *S) {
8899 if (const SCEVUnknown *C = dyn_cast<SCEVUnknown>(S)) {
8900 if (isa<UndefValue>(C->getValue()))
8901 Found = true;
8902 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
8903 if (isa<UndefValue>(C->getValue()))
8904 Found = true;
8905 }
8906
8907 // Keep looking if we haven't found it yet.
8908 return !Found;
8909 }
8910 bool isDone() const {
8911 // Stop recursion if we have found an undef.
8912 return Found;
8913 }
8914};
8915}
8916
8917// Return true when S contains at least an undef value.
8918static inline bool
8919containsUndefs(const SCEV *S) {
8920 FindUndefs F;
8921 SCEVTraversal<FindUndefs> ST(F);
8922 ST.visitAll(S);
8923
8924 return F.Found;
8925}
8926
8927namespace {
8928// Collect all steps of SCEV expressions.
8929struct SCEVCollectStrides {
8930 ScalarEvolution &SE;
8931 SmallVectorImpl<const SCEV *> &Strides;
8932
8933 SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S)
8934 : SE(SE), Strides(S) {}
8935
8936 bool follow(const SCEV *S) {
8937 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
8938 Strides.push_back(AR->getStepRecurrence(SE));
8939 return true;
8940 }
8941 bool isDone() const { return false; }
8942};
8943
8944// Collect all SCEVUnknown and SCEVMulExpr expressions.
8945struct SCEVCollectTerms {
8946 SmallVectorImpl<const SCEV *> &Terms;
8947
8948 SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T)
8949 : Terms(T) {}
8950
8951 bool follow(const SCEV *S) {
8952 if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S)) {
8953 if (!containsUndefs(S))
8954 Terms.push_back(S);
8955
8956 // Stop recursion: once we collected a term, do not walk its operands.
8957 return false;
8958 }
8959
8960 // Keep looking.
8961 return true;
8962 }
8963 bool isDone() const { return false; }
8964};
8965
8966// Check if a SCEV contains an AddRecExpr.
8967struct SCEVHasAddRec {
8968 bool &ContainsAddRec;
8969
8970 SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) {
8971 ContainsAddRec = false;
8972 }
8973
8974 bool follow(const SCEV *S) {
8975 if (isa<SCEVAddRecExpr>(S)) {
8976 ContainsAddRec = true;
8977
8978 // Stop recursion: once we collected a term, do not walk its operands.
8979 return false;
8980 }
8981
8982 // Keep looking.
8983 return true;
8984 }
8985 bool isDone() const { return false; }
8986};
8987
8988// Find factors that are multiplied with an expression that (possibly as a
8989// subexpression) contains an AddRecExpr. In the expression:
8990//
8991// 8 * (100 + %p * %q * (%a + {0, +, 1}_loop))
8992//
8993// "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)"
8994// that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size
8995// parameters as they form a product with an induction variable.
8996//
8997// This collector expects all array size parameters to be in the same MulExpr.
8998// It might be necessary to later add support for collecting parameters that are
8999// spread over different nested MulExpr.
9000struct SCEVCollectAddRecMultiplies {
9001 SmallVectorImpl<const SCEV *> &Terms;
9002 ScalarEvolution &SE;
9003
9004 SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE)
9005 : Terms(T), SE(SE) {}
9006
9007 bool follow(const SCEV *S) {
9008 if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) {
9009 bool HasAddRec = false;
9010 SmallVector<const SCEV *, 0> Operands;
9011 for (auto Op : Mul->operands()) {
9012 if (isa<SCEVUnknown>(Op)) {
9013 Operands.push_back(Op);
9014 } else {
9015 bool ContainsAddRec;
9016 SCEVHasAddRec ContiansAddRec(ContainsAddRec);
9017 visitAll(Op, ContiansAddRec);
9018 HasAddRec |= ContainsAddRec;
9019 }
9020 }
9021 if (Operands.size() == 0)
9022 return true;
9023
9024 if (!HasAddRec)
9025 return false;
9026
9027 Terms.push_back(SE.getMulExpr(Operands));
9028 // Stop recursion: once we collected a term, do not walk its operands.
9029 return false;
9030 }
9031
9032 // Keep looking.
9033 return true;
9034 }
9035 bool isDone() const { return false; }
9036};
9037}
9038
9039/// Find parametric terms in this SCEVAddRecExpr. We first for parameters in
9040/// two places:
9041/// 1) The strides of AddRec expressions.
9042/// 2) Unknowns that are multiplied with AddRec expressions.
9043void ScalarEvolution::collectParametricTerms(const SCEV *Expr,
9044 SmallVectorImpl<const SCEV *> &Terms) {
9045 SmallVector<const SCEV *, 4> Strides;
9046 SCEVCollectStrides StrideCollector(*this, Strides);
9047 visitAll(Expr, StrideCollector);
9048
9049 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9050 dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9051 for (const SCEV *S : Strides)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9052 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9053 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0);
9054
9055 for (const SCEV *S : Strides) {
9056 SCEVCollectTerms TermCollector(Terms);
9057 visitAll(S, TermCollector);
9058 }
9059
9060 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9061 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9062 for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9063 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9064 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0);
9065
9066 SCEVCollectAddRecMultiplies MulCollector(Terms, *this);
9067 visitAll(Expr, MulCollector);
9068}
9069
9070static bool findArrayDimensionsRec(ScalarEvolution &SE,
9071 SmallVectorImpl<const SCEV *> &Terms,
9072 SmallVectorImpl<const SCEV *> &Sizes) {
9073 int Last = Terms.size() - 1;
9074 const SCEV *Step = Terms[Last];
9075
9076 // End of recursion.
9077 if (Last == 0) {
9078 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) {
9079 SmallVector<const SCEV *, 2> Qs;
9080 for (const SCEV *Op : M->operands())
9081 if (!isa<SCEVConstant>(Op))
9082 Qs.push_back(Op);
9083
9084 Step = SE.getMulExpr(Qs);
9085 }
9086
9087 Sizes.push_back(Step);
9088 return true;
9089 }
9090
9091 for (const SCEV *&Term : Terms) {
9092 // Normalize the terms before the next call to findArrayDimensionsRec.
9093 const SCEV *Q, *R;
9094 SCEVDivision::divide(SE, Term, Step, &Q, &R);
9095
9096 // Bail out when GCD does not evenly divide one of the terms.
9097 if (!R->isZero())
9098 return false;
9099
9100 Term = Q;
9101 }
9102
9103 // Remove all SCEVConstants.
9104 Terms.erase(std::remove_if(Terms.begin(), Terms.end(), [](const SCEV *E) {
9105 return isa<SCEVConstant>(E);
9106 }),
9107 Terms.end());
9108
9109 if (Terms.size() > 0)
9110 if (!findArrayDimensionsRec(SE, Terms, Sizes))
9111 return false;
9112
9113 Sizes.push_back(Step);
9114 return true;
9115}
9116
9117// Returns true when S contains at least a SCEVUnknown parameter.
9118static inline bool
9119containsParameters(const SCEV *S) {
9120 struct FindParameter {
9121 bool FoundParameter;
9122 FindParameter() : FoundParameter(false) {}
9123
9124 bool follow(const SCEV *S) {
9125 if (isa<SCEVUnknown>(S)) {
9126 FoundParameter = true;
9127 // Stop recursion: we found a parameter.
9128 return false;
9129 }
9130 // Keep looking.
9131 return true;
9132 }
9133 bool isDone() const {
9134 // Stop recursion if we have found a parameter.
9135 return FoundParameter;
9136 }
9137 };
9138
9139 FindParameter F;
9140 SCEVTraversal<FindParameter> ST(F);
9141 ST.visitAll(S);
9142
9143 return F.FoundParameter;
9144}
9145
9146// Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter.
9147static inline bool
9148containsParameters(SmallVectorImpl<const SCEV *> &Terms) {
9149 for (const SCEV *T : Terms)
9150 if (containsParameters(T))
9151 return true;
9152 return false;
9153}
9154
9155// Return the number of product terms in S.
9156static inline int numberOfTerms(const SCEV *S) {
9157 if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S))
9158 return Expr->getNumOperands();
9159 return 1;
9160}
9161
9162static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) {
9163 if (isa<SCEVConstant>(T))
9164 return nullptr;
9165
9166 if (isa<SCEVUnknown>(T))
9167 return T;
9168
9169 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) {
9170 SmallVector<const SCEV *, 2> Factors;
9171 for (const SCEV *Op : M->operands())
9172 if (!isa<SCEVConstant>(Op))
9173 Factors.push_back(Op);
9174
9175 return SE.getMulExpr(Factors);
9176 }
9177
9178 return T;
9179}
9180
9181/// Return the size of an element read or written by Inst.
9182const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
9183 Type *Ty;
9184 if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
9185 Ty = Store->getValueOperand()->getType();
9186 else if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
9187 Ty = Load->getType();
9188 else
9189 return nullptr;
9190
9191 Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty));
9192 return getSizeOfExpr(ETy, Ty);
9193}
9194
9195/// Second step of delinearization: compute the array dimensions Sizes from the
9196/// set of Terms extracted from the memory access function of this SCEVAddRec.
9197void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
9198 SmallVectorImpl<const SCEV *> &Sizes,
9199 const SCEV *ElementSize) const {
9200
9201 if (Terms.size() < 1 || !ElementSize)
9202 return;
9203
9204 // Early return when Terms do not contain parameters: we do not delinearize
9205 // non parametric SCEVs.
9206 if (!containsParameters(Terms))
9207 return;
9208
9209 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9210 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9211 for (const SCEV *T : Terms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9212 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9213 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0);
9214
9215 // Remove duplicates.
9216 std::sort(Terms.begin(), Terms.end());
9217 Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end());
9218
9219 // Put larger terms first.
9220 std::sort(Terms.begin(), Terms.end(), [](const SCEV *LHS, const SCEV *RHS) {
9221 return numberOfTerms(LHS) > numberOfTerms(RHS);
9222 });
9223
9224 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
9225
9226 // Try to divide all terms by the element size. If term is not divisible by
9227 // element size, proceed with the original term.
9228 for (const SCEV *&Term : Terms) {
9229 const SCEV *Q, *R;
9230 SCEVDivision::divide(SE, Term, ElementSize, &Q, &R);
9231 if (!Q->isZero())
9232 Term = Q;
9233 }
9234
9235 SmallVector<const SCEV *, 4> NewTerms;
9236
9237 // Remove constant factors.
9238 for (const SCEV *T : Terms)
9239 if (const SCEV *NewT = removeConstantFactors(SE, T))
9240 NewTerms.push_back(NewT);
9241
9242 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0)
9243 dbgs() << "Terms after sorting:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0)
9244 for (const SCEV *T : NewTerms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0)
9245 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0)
9246 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0);
9247
9248 if (NewTerms.empty() ||
9249 !findArrayDimensionsRec(SE, NewTerms, Sizes)) {
9250 Sizes.clear();
9251 return;
9252 }
9253
9254 // The last element to be pushed into Sizes is the size of an element.
9255 Sizes.push_back(ElementSize);
9256
9257 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9258 dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9259 for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9260 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9261 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0);
9262}
9263
9264/// Third step of delinearization: compute the access functions for the
9265/// Subscripts based on the dimensions in Sizes.
9266void ScalarEvolution::computeAccessFunctions(
9267 const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts,
9268 SmallVectorImpl<const SCEV *> &Sizes) {
9269
9270 // Early exit in case this SCEV is not an affine multivariate function.
9271 if (Sizes.empty())
9272 return;
9273
9274 if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr))
9275 if (!AR->isAffine())
9276 return;
9277
9278 const SCEV *Res = Expr;
9279 int Last = Sizes.size() - 1;
9280 for (int i = Last; i >= 0; i--) {
9281 const SCEV *Q, *R;
9282 SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R);
9283
9284 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0)
9285 dbgs() << "Res: " << *Res << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0)
9286 dbgs() << "Sizes[i]: " << *Sizes[i] << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0)
9287 dbgs() << "Res divided by Sizes[i]:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0)
9288 dbgs() << "Quotient: " << *Q << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0)
9289 dbgs() << "Remainder: " << *R << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0)
9290 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Res: " << *Res
<< "\n"; dbgs() << "Sizes[i]: " << *Sizes[
i] << "\n"; dbgs() << "Res divided by Sizes[i]:\n"
; dbgs() << "Quotient: " << *Q << "\n"; dbgs
() << "Remainder: " << *R << "\n"; }; } } while
(0);
9291
9292 Res = Q;
9293
9294 // Do not record the last subscript corresponding to the size of elements in
9295 // the array.
9296 if (i == Last) {
9297
9298 // Bail out if the remainder is too complex.
9299 if (isa<SCEVAddRecExpr>(R)) {
9300 Subscripts.clear();
9301 Sizes.clear();
9302 return;
9303 }
9304
9305 continue;
9306 }
9307
9308 // Record the access function for the current subscript.
9309 Subscripts.push_back(R);
9310 }
9311
9312 // Also push in last position the remainder of the last division: it will be
9313 // the access function of the innermost dimension.
9314 Subscripts.push_back(Res);
9315
9316 std::reverse(Subscripts.begin(), Subscripts.end());
9317
9318 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9319 dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9320 for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9321 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9322 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0);
9323}
9324
9325/// Splits the SCEV into two vectors of SCEVs representing the subscripts and
9326/// sizes of an array access. Returns the remainder of the delinearization that
9327/// is the offset start of the array. The SCEV->delinearize algorithm computes
9328/// the multiples of SCEV coefficients: that is a pattern matching of sub
9329/// expressions in the stride and base of a SCEV corresponding to the
9330/// computation of a GCD (greatest common divisor) of base and stride. When
9331/// SCEV->delinearize fails, it returns the SCEV unchanged.
9332///
9333/// For example: when analyzing the memory access A[i][j][k] in this loop nest
9334///
9335/// void foo(long n, long m, long o, double A[n][m][o]) {
9336///
9337/// for (long i = 0; i < n; i++)
9338/// for (long j = 0; j < m; j++)
9339/// for (long k = 0; k < o; k++)
9340/// A[i][j][k] = 1.0;
9341/// }
9342///
9343/// the delinearization input is the following AddRec SCEV:
9344///
9345/// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k>
9346///
9347/// From this SCEV, we are able to say that the base offset of the access is %A
9348/// because it appears as an offset that does not divide any of the strides in
9349/// the loops:
9350///
9351/// CHECK: Base offset: %A
9352///
9353/// and then SCEV->delinearize determines the size of some of the dimensions of
9354/// the array as these are the multiples by which the strides are happening:
9355///
9356/// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes.
9357///
9358/// Note that the outermost dimension remains of UnknownSize because there are
9359/// no strides that would help identifying the size of the last dimension: when
9360/// the array has been statically allocated, one could compute the size of that
9361/// dimension by dividing the overall size of the array by the size of the known
9362/// dimensions: %m * %o * 8.
9363///
9364/// Finally delinearize provides the access functions for the array reference
9365/// that does correspond to A[i][j][k] of the above C testcase:
9366///
9367/// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>]
9368///
9369/// The testcases are checking the output of a function pass:
9370/// DelinearizationPass that walks through all loads and stores of a function
9371/// asking for the SCEV of the memory access with respect to all enclosing
9372/// loops, calling SCEV->delinearize on that and printing the results.
9373
9374void ScalarEvolution::delinearize(const SCEV *Expr,
9375 SmallVectorImpl<const SCEV *> &Subscripts,
9376 SmallVectorImpl<const SCEV *> &Sizes,
9377 const SCEV *ElementSize) {
9378 // First step: collect parametric terms.
9379 SmallVector<const SCEV *, 4> Terms;
9380 collectParametricTerms(Expr, Terms);
9381
9382 if (Terms.empty())
9383 return;
9384
9385 // Second step: find subscript sizes.
9386 findArrayDimensions(Terms, Sizes, ElementSize);
9387
9388 if (Sizes.empty())
9389 return;
9390
9391 // Third step: compute the access functions for each subscript.
9392 computeAccessFunctions(Expr, Subscripts, Sizes);
9393
9394 if (Subscripts.empty())
9395 return;
9396
9397 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9398 dbgs() << "succeeded to delinearize " << *Expr << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9399 dbgs() << "ArrayDecl[UnknownSize]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9400 for (const SCEV *S : Sizes)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9401 dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9402
9403 dbgs() << "\nArrayRef";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9404 for (const SCEV *S : Subscripts)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9405 dbgs() << "[" << *S << "]";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9406 dbgs() << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0)
9407 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "succeeded to delinearize "
<< *Expr << "\n"; dbgs() << "ArrayDecl[UnknownSize]"
; for (const SCEV *S : Sizes) dbgs() << "[" << *S
<< "]"; dbgs() << "\nArrayRef"; for (const SCEV *
S : Subscripts) dbgs() << "[" << *S << "]";
dbgs() << "\n"; }; } } while (0);
9408}
9409
9410//===----------------------------------------------------------------------===//
9411// SCEVCallbackVH Class Implementation
9412//===----------------------------------------------------------------------===//
9413
9414void ScalarEvolution::SCEVCallbackVH::deleted() {
9415 assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!"
) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9415, __PRETTY_FUNCTION__));
9416 if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
9417 SE->ConstantEvolutionLoopExitValue.erase(PN);
9418 SE->eraseValueFromMap(getValPtr());
9419 // this now dangles!
9420}
9421
9422void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
9423 assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!")((SE && "SCEVCallbackVH called with a null ScalarEvolution!"
) ? static_cast<void> (0) : __assert_fail ("SE && \"SCEVCallbackVH called with a null ScalarEvolution!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9423, __PRETTY_FUNCTION__));
9424
9425 // Forget all the expressions associated with users of the old value,
9426 // so that future queries will recompute the expressions using the new
9427 // value.
9428 Value *Old = getValPtr();
9429 SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end());
9430 SmallPtrSet<User *, 8> Visited;
9431 while (!Worklist.empty()) {
9432 User *U = Worklist.pop_back_val();
9433 // Deleting the Old value will cause this to dangle. Postpone
9434 // that until everything else is done.
9435 if (U == Old)
9436 continue;
9437 if (!Visited.insert(U).second)
9438 continue;
9439 if (PHINode *PN = dyn_cast<PHINode>(U))
9440 SE->ConstantEvolutionLoopExitValue.erase(PN);
9441 SE->eraseValueFromMap(U);
9442 Worklist.insert(Worklist.end(), U->user_begin(), U->user_end());
9443 }
9444 // Delete the Old value.
9445 if (PHINode *PN = dyn_cast<PHINode>(Old))
9446 SE->ConstantEvolutionLoopExitValue.erase(PN);
9447 SE->eraseValueFromMap(Old);
9448 // this now dangles!
9449}
9450
9451ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
9452 : CallbackVH(V), SE(se) {}
9453
9454//===----------------------------------------------------------------------===//
9455// ScalarEvolution Class Implementation
9456//===----------------------------------------------------------------------===//
9457
9458ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI,
9459 AssumptionCache &AC, DominatorTree &DT,
9460 LoopInfo &LI)
9461 : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI),
9462 CouldNotCompute(new SCEVCouldNotCompute()),
9463 WalkingBEDominatingConds(false), ProvingSplitPredicate(false),
9464 ValuesAtScopes(64), LoopDispositions(64), BlockDispositions(64),
9465 FirstUnknown(nullptr) {}
9466
9467ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg)
9468 : F(Arg.F), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT), LI(Arg.LI),
9469 CouldNotCompute(std::move(Arg.CouldNotCompute)),
9470 ValueExprMap(std::move(Arg.ValueExprMap)),
9471 WalkingBEDominatingConds(false), ProvingSplitPredicate(false),
9472 BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
9473 PredicatedBackedgeTakenCounts(
9474 std::move(Arg.PredicatedBackedgeTakenCounts)),
9475 ConstantEvolutionLoopExitValue(
9476 std::move(Arg.ConstantEvolutionLoopExitValue)),
9477 ValuesAtScopes(std::move(Arg.ValuesAtScopes)),
9478 LoopDispositions(std::move(Arg.LoopDispositions)),
9479 BlockDispositions(std::move(Arg.BlockDispositions)),
9480 UnsignedRanges(std::move(Arg.UnsignedRanges)),
9481 SignedRanges(std::move(Arg.SignedRanges)),
9482 UniqueSCEVs(std::move(Arg.UniqueSCEVs)),
9483 UniquePreds(std::move(Arg.UniquePreds)),
9484 SCEVAllocator(std::move(Arg.SCEVAllocator)),
9485 FirstUnknown(Arg.FirstUnknown) {
9486 Arg.FirstUnknown = nullptr;
9487}
9488
9489ScalarEvolution::~ScalarEvolution() {
9490 // Iterate through all the SCEVUnknown instances and call their
9491 // destructors, so that they release their references to their values.
9492 for (SCEVUnknown *U = FirstUnknown; U;) {
9493 SCEVUnknown *Tmp = U;
9494 U = U->Next;
9495 Tmp->~SCEVUnknown();
9496 }
9497 FirstUnknown = nullptr;
9498
9499 ExprValueMap.clear();
9500 ValueExprMap.clear();
9501 HasRecMap.clear();
9502
9503 // Free any extra memory created for ExitNotTakenInfo in the unlikely event
9504 // that a loop had multiple computable exits.
9505 for (auto &BTCI : BackedgeTakenCounts)
9506 BTCI.second.clear();
9507 for (auto &BTCI : PredicatedBackedgeTakenCounts)
9508 BTCI.second.clear();
9509
9510 assert(PendingLoopPredicates.empty() && "isImpliedCond garbage")((PendingLoopPredicates.empty() && "isImpliedCond garbage"
) ? static_cast<void> (0) : __assert_fail ("PendingLoopPredicates.empty() && \"isImpliedCond garbage\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9510, __PRETTY_FUNCTION__));
9511 assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!"
) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9511, __PRETTY_FUNCTION__));
9512 assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"
) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9512, __PRETTY_FUNCTION__));
9513}
9514
9515bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
9516 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
9517}
9518
9519static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
9520 const Loop *L) {
9521 // Print all inner loops first
9522 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
9523 PrintLoopInfo(OS, SE, *I);
9524
9525 OS << "Loop ";
9526 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9527 OS << ": ";
9528
9529 SmallVector<BasicBlock *, 8> ExitBlocks;
9530 L->getExitBlocks(ExitBlocks);
9531 if (ExitBlocks.size() != 1)
9532 OS << "<multiple exits> ";
9533
9534 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
9535 OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L);
9536 } else {
9537 OS << "Unpredictable backedge-taken count. ";
9538 }
9539
9540 OS << "\n"
9541 "Loop ";
9542 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9543 OS << ": ";
9544
9545 if (!isa<SCEVCouldNotCompute>(SE->getMaxBackedgeTakenCount(L))) {
9546 OS << "max backedge-taken count is " << *SE->getMaxBackedgeTakenCount(L);
9547 } else {
9548 OS << "Unpredictable max backedge-taken count. ";
9549 }
9550
9551 OS << "\n"
9552 "Loop ";
9553 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9554 OS << ": ";
9555
9556 SCEVUnionPredicate Pred;
9557 auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred);
9558 if (!isa<SCEVCouldNotCompute>(PBT)) {
9559 OS << "Predicated backedge-taken count is " << *PBT << "\n";
9560 OS << " Predicates:\n";
9561 Pred.print(OS, 4);
9562 } else {
9563 OS << "Unpredictable predicated backedge-taken count. ";
9564 }
9565 OS << "\n";
9566}
9567
9568void ScalarEvolution::print(raw_ostream &OS) const {
9569 // ScalarEvolution's implementation of the print method is to print
9570 // out SCEV values of all instructions that are interesting. Doing
9571 // this potentially causes it to create new SCEV objects though,
9572 // which technically conflicts with the const qualifier. This isn't
9573 // observable from outside the class though, so casting away the
9574 // const isn't dangerous.
9575 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
9576
9577 OS << "Classifying expressions for: ";
9578 F.printAsOperand(OS, /*PrintType=*/false);
9579 OS << "\n";
9580 for (Instruction &I : instructions(F))
9581 if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) {
9582 OS << I << '\n';
9583 OS << " --> ";
9584 const SCEV *SV = SE.getSCEV(&I);
9585 SV->print(OS);
9586 if (!isa<SCEVCouldNotCompute>(SV)) {
9587 OS << " U: ";
9588 SE.getUnsignedRange(SV).print(OS);
9589 OS << " S: ";
9590 SE.getSignedRange(SV).print(OS);
9591 }
9592
9593 const Loop *L = LI.getLoopFor(I.getParent());
9594
9595 const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
9596 if (AtUse != SV) {
9597 OS << " --> ";
9598 AtUse->print(OS);
9599 if (!isa<SCEVCouldNotCompute>(AtUse)) {
9600 OS << " U: ";
9601 SE.getUnsignedRange(AtUse).print(OS);
9602 OS << " S: ";
9603 SE.getSignedRange(AtUse).print(OS);
9604 }
9605 }
9606
9607 if (L) {
9608 OS << "\t\t" "Exits: ";
9609 const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
9610 if (!SE.isLoopInvariant(ExitValue, L)) {
9611 OS << "<<Unknown>>";
9612 } else {
9613 OS << *ExitValue;
9614 }
9615 }
9616
9617 OS << "\n";
9618 }
9619
9620 OS << "Determining loop execution counts for: ";
9621 F.printAsOperand(OS, /*PrintType=*/false);
9622 OS << "\n";
9623 for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
9624 PrintLoopInfo(OS, &SE, *I);
9625}
9626
9627ScalarEvolution::LoopDisposition
9628ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
9629 auto &Values = LoopDispositions[S];
9630 for (auto &V : Values) {
9631 if (V.getPointer() == L)
9632 return V.getInt();
9633 }
9634 Values.emplace_back(L, LoopVariant);
9635 LoopDisposition D = computeLoopDisposition(S, L);
9636 auto &Values2 = LoopDispositions[S];
9637 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
9638 if (V.getPointer() == L) {
9639 V.setInt(D);
9640 break;
9641 }
9642 }
9643 return D;
9644}
9645
9646ScalarEvolution::LoopDisposition
9647ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
9648 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
9649 case scConstant:
9650 return LoopInvariant;
9651 case scTruncate:
9652 case scZeroExtend:
9653 case scSignExtend:
9654 return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
9655 case scAddRecExpr: {
9656 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
9657
9658 // If L is the addrec's loop, it's computable.
9659 if (AR->getLoop() == L)
9660 return LoopComputable;
9661
9662 // Add recurrences are never invariant in the function-body (null loop).
9663 if (!L)
9664 return LoopVariant;
9665
9666 // This recurrence is variant w.r.t. L if L contains AR's loop.
9667 if (L->contains(AR->getLoop()))
9668 return LoopVariant;
9669
9670 // This recurrence is invariant w.r.t. L if AR's loop contains L.
9671 if (AR->getLoop()->contains(L))
9672 return LoopInvariant;
9673
9674 // This recurrence is variant w.r.t. L if any of its operands
9675 // are variant.
9676 for (auto *Op : AR->operands())
9677 if (!isLoopInvariant(Op, L))
9678 return LoopVariant;
9679
9680 // Otherwise it's loop-invariant.
9681 return LoopInvariant;
9682 }
9683 case scAddExpr:
9684 case scMulExpr:
9685 case scUMaxExpr:
9686 case scSMaxExpr: {
9687 bool HasVarying = false;
9688 for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) {
9689 LoopDisposition D = getLoopDisposition(Op, L);
9690 if (D == LoopVariant)
9691 return LoopVariant;
9692 if (D == LoopComputable)
9693 HasVarying = true;
9694 }
9695 return HasVarying ? LoopComputable : LoopInvariant;
9696 }
9697 case scUDivExpr: {
9698 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
9699 LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
9700 if (LD == LoopVariant)
9701 return LoopVariant;
9702 LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
9703 if (RD == LoopVariant)
9704 return LoopVariant;
9705 return (LD == LoopInvariant && RD == LoopInvariant) ?
9706 LoopInvariant : LoopComputable;
9707 }
9708 case scUnknown:
9709 // All non-instruction values are loop invariant. All instructions are loop
9710 // invariant if they are not contained in the specified loop.
9711 // Instructions are never considered invariant in the function body
9712 // (null loop) because they are defined within the "loop".
9713 if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
9714 return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
9715 return LoopInvariant;
9716 case scCouldNotCompute:
9717 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9717);
9718 }
9719 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9719);
9720}
9721
9722bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
9723 return getLoopDisposition(S, L) == LoopInvariant;
9724}
9725
9726bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
9727 return getLoopDisposition(S, L) == LoopComputable;
9728}
9729
9730ScalarEvolution::BlockDisposition
9731ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
9732 auto &Values = BlockDispositions[S];
9733 for (auto &V : Values) {
9734 if (V.getPointer() == BB)
9735 return V.getInt();
9736 }
9737 Values.emplace_back(BB, DoesNotDominateBlock);
9738 BlockDisposition D = computeBlockDisposition(S, BB);
9739 auto &Values2 = BlockDispositions[S];
9740 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
9741 if (V.getPointer() == BB) {
9742 V.setInt(D);
9743 break;
9744 }
9745 }
9746 return D;
9747}
9748
9749ScalarEvolution::BlockDisposition
9750ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
9751 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
9752 case scConstant:
9753 return ProperlyDominatesBlock;
9754 case scTruncate:
9755 case scZeroExtend:
9756 case scSignExtend:
9757 return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
9758 case scAddRecExpr: {
9759 // This uses a "dominates" query instead of "properly dominates" query
9760 // to test for proper dominance too, because the instruction which
9761 // produces the addrec's value is a PHI, and a PHI effectively properly
9762 // dominates its entire containing block.
9763 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
9764 if (!DT.dominates(AR->getLoop()->getHeader(), BB))
9765 return DoesNotDominateBlock;
9766 }
9767 // FALL THROUGH into SCEVNAryExpr handling.
9768 case scAddExpr:
9769 case scMulExpr:
9770 case scUMaxExpr:
9771 case scSMaxExpr: {
9772 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
9773 bool Proper = true;
9774 for (const SCEV *NAryOp : NAry->operands()) {
9775 BlockDisposition D = getBlockDisposition(NAryOp, BB);
9776 if (D == DoesNotDominateBlock)
9777 return DoesNotDominateBlock;
9778 if (D == DominatesBlock)
9779 Proper = false;
9780 }
9781 return Proper ? ProperlyDominatesBlock : DominatesBlock;
9782 }
9783 case scUDivExpr: {
9784 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
9785 const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
9786 BlockDisposition LD = getBlockDisposition(LHS, BB);
9787 if (LD == DoesNotDominateBlock)
9788 return DoesNotDominateBlock;
9789 BlockDisposition RD = getBlockDisposition(RHS, BB);
9790 if (RD == DoesNotDominateBlock)
9791 return DoesNotDominateBlock;
9792 return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
9793 ProperlyDominatesBlock : DominatesBlock;
9794 }
9795 case scUnknown:
9796 if (Instruction *I =
9797 dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
9798 if (I->getParent() == BB)
9799 return DominatesBlock;
9800 if (DT.properlyDominates(I->getParent(), BB))
9801 return ProperlyDominatesBlock;
9802 return DoesNotDominateBlock;
9803 }
9804 return ProperlyDominatesBlock;
9805 case scCouldNotCompute:
9806 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9806);
9807 }
9808 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9808);
9809}
9810
9811bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
9812 return getBlockDisposition(S, BB) >= DominatesBlock;
9813}
9814
9815bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
9816 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
9817}
9818
9819bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
9820 // Search for a SCEV expression node within an expression tree.
9821 // Implements SCEVTraversal::Visitor.
9822 struct SCEVSearch {
9823 const SCEV *Node;
9824 bool IsFound;
9825
9826 SCEVSearch(const SCEV *N): Node(N), IsFound(false) {}
9827
9828 bool follow(const SCEV *S) {
9829 IsFound |= (S == Node);
9830 return !IsFound;
9831 }
9832 bool isDone() const { return IsFound; }
9833 };
9834
9835 SCEVSearch Search(Op);
9836 visitAll(S, Search);
9837 return Search.IsFound;
9838}
9839
9840void ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
9841 ValuesAtScopes.erase(S);
9842 LoopDispositions.erase(S);
9843 BlockDispositions.erase(S);
9844 UnsignedRanges.erase(S);
9845 SignedRanges.erase(S);
9846 ExprValueMap.erase(S);
9847 HasRecMap.erase(S);
9848
9849 auto RemoveSCEVFromBackedgeMap =
9850 [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
9851 for (auto I = Map.begin(), E = Map.end(); I != E;) {
9852 BackedgeTakenInfo &BEInfo = I->second;
9853 if (BEInfo.hasOperand(S, this)) {
9854 BEInfo.clear();
9855 Map.erase(I++);
9856 } else
9857 ++I;
9858 }
9859 };
9860
9861 RemoveSCEVFromBackedgeMap(BackedgeTakenCounts);
9862 RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
9863}
9864
9865typedef DenseMap<const Loop *, std::string> VerifyMap;
9866
9867/// replaceSubString - Replaces all occurrences of From in Str with To.
9868static void replaceSubString(std::string &Str, StringRef From, StringRef To) {
9869 size_t Pos = 0;
9870 while ((Pos = Str.find(From, Pos)) != std::string::npos) {
9871 Str.replace(Pos, From.size(), To.data(), To.size());
9872 Pos += To.size();
9873 }
9874}
9875
9876/// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis.
9877static void
9878getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) {
9879 std::string &S = Map[L];
9880 if (S.empty()) {
9881 raw_string_ostream OS(S);
9882 SE.getBackedgeTakenCount(L)->print(OS);
9883
9884 // false and 0 are semantically equivalent. This can happen in dead loops.
9885 replaceSubString(OS.str(), "false", "0");
9886 // Remove wrap flags, their use in SCEV is highly fragile.
9887 // FIXME: Remove this when SCEV gets smarter about them.
9888 replaceSubString(OS.str(), "<nw>", "");
9889 replaceSubString(OS.str(), "<nsw>", "");
9890 replaceSubString(OS.str(), "<nuw>", "");
9891 }
9892
9893 for (auto *R : reverse(*L))
9894 getLoopBackedgeTakenCounts(R, Map, SE); // recurse.
9895}
9896
9897void ScalarEvolution::verify() const {
9898 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
9899
9900 // Gather stringified backedge taken counts for all loops using SCEV's caches.
9901 // FIXME: It would be much better to store actual values instead of strings,
9902 // but SCEV pointers will change if we drop the caches.
9903 VerifyMap BackedgeDumpsOld, BackedgeDumpsNew;
9904 for (LoopInfo::reverse_iterator I = LI.rbegin(), E = LI.rend(); I != E; ++I)
9905 getLoopBackedgeTakenCounts(*I, BackedgeDumpsOld, SE);
9906
9907 // Gather stringified backedge taken counts for all loops using a fresh
9908 // ScalarEvolution object.
9909 ScalarEvolution SE2(F, TLI, AC, DT, LI);
9910 for (LoopInfo::reverse_iterator I = LI.rbegin(), E = LI.rend(); I != E; ++I)
9911 getLoopBackedgeTakenCounts(*I, BackedgeDumpsNew, SE2);
9912
9913 // Now compare whether they're the same with and without caches. This allows
9914 // verifying that no pass changed the cache.
9915 assert(BackedgeDumpsOld.size() == BackedgeDumpsNew.size() &&((BackedgeDumpsOld.size() == BackedgeDumpsNew.size() &&
"New loops suddenly appeared!") ? static_cast<void> (0
) : __assert_fail ("BackedgeDumpsOld.size() == BackedgeDumpsNew.size() && \"New loops suddenly appeared!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9916, __PRETTY_FUNCTION__))
9916 "New loops suddenly appeared!")((BackedgeDumpsOld.size() == BackedgeDumpsNew.size() &&
"New loops suddenly appeared!") ? static_cast<void> (0
) : __assert_fail ("BackedgeDumpsOld.size() == BackedgeDumpsNew.size() && \"New loops suddenly appeared!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9916, __PRETTY_FUNCTION__));
9917
9918 for (VerifyMap::iterator OldI = BackedgeDumpsOld.begin(),
9919 OldE = BackedgeDumpsOld.end(),
9920 NewI = BackedgeDumpsNew.begin();
9921 OldI != OldE; ++OldI, ++NewI) {
9922 assert(OldI->first == NewI->first && "Loop order changed!")((OldI->first == NewI->first && "Loop order changed!"
) ? static_cast<void> (0) : __assert_fail ("OldI->first == NewI->first && \"Loop order changed!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 9922, __PRETTY_FUNCTION__));
9923
9924 // Compare the stringified SCEVs. We don't care if undef backedgetaken count
9925 // changes.
9926 // FIXME: We currently ignore SCEV changes from/to CouldNotCompute. This
9927 // means that a pass is buggy or SCEV has to learn a new pattern but is
9928 // usually not harmful.
9929 if (OldI->second != NewI->second &&
9930 OldI->second.find("undef") == std::string::npos &&
9931 NewI->second.find("undef") == std::string::npos &&
9932 OldI->second != "***COULDNOTCOMPUTE***" &&
9933 NewI->second != "***COULDNOTCOMPUTE***") {
9934 dbgs() << "SCEVValidator: SCEV for loop '"
9935 << OldI->first->getHeader()->getName()
9936 << "' changed from '" << OldI->second
9937 << "' to '" << NewI->second << "'!\n";
9938 std::abort();
9939 }
9940 }
9941
9942 // TODO: Verify more things.
9943}
9944
9945char ScalarEvolutionAnalysis::PassID;
9946
9947ScalarEvolution ScalarEvolutionAnalysis::run(Function &F,
9948 AnalysisManager<Function> &AM) {
9949 return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F),
9950 AM.getResult<AssumptionAnalysis>(F),
9951 AM.getResult<DominatorTreeAnalysis>(F),
9952 AM.getResult<LoopAnalysis>(F));
9953}
9954
9955PreservedAnalyses
9956ScalarEvolutionPrinterPass::run(Function &F, AnalysisManager<Function> &AM) {
9957 AM.getResult<ScalarEvolutionAnalysis>(F).print(OS);
9958 return PreservedAnalyses::all();
9959}
9960
9961INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void* initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
9962 "Scalar Evolution Analysis", false, true)static void* initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
9963INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
9964INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
9965INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
9966INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
9967INITIALIZE_PASS_END(ScalarEvolutionWrapperPass, "scalar-evolution",PassInfo *PI = new PassInfo("Scalar Evolution Analysis", "scalar-evolution"
, & ScalarEvolutionWrapperPass ::ID, PassInfo::NormalCtor_t
(callDefaultCtor< ScalarEvolutionWrapperPass >), false,
true); Registry.registerPass(*PI, true); return PI; } void llvm
::initializeScalarEvolutionWrapperPassPass(PassRegistry &
Registry) { static volatile sys::cas_flag initialized = 0; sys
::cas_flag old_val = sys::CompareAndSwap(&initialized, 1,
0); if (old_val == 0) { initializeScalarEvolutionWrapperPassPassOnce
(Registry); sys::MemoryFence(); ; ; initialized = 2; ; } else
{ sys::cas_flag tmp = initialized; sys::MemoryFence(); while
(tmp != 2) { tmp = initialized; sys::MemoryFence(); } } ; }
9968 "Scalar Evolution Analysis", false, true)PassInfo *PI = new PassInfo("Scalar Evolution Analysis", "scalar-evolution"
, & ScalarEvolutionWrapperPass ::ID, PassInfo::NormalCtor_t
(callDefaultCtor< ScalarEvolutionWrapperPass >), false,
true); Registry.registerPass(*PI, true); return PI; } void llvm
::initializeScalarEvolutionWrapperPassPass(PassRegistry &
Registry) { static volatile sys::cas_flag initialized = 0; sys
::cas_flag old_val = sys::CompareAndSwap(&initialized, 1,
0); if (old_val == 0) { initializeScalarEvolutionWrapperPassPassOnce
(Registry); sys::MemoryFence(); ; ; initialized = 2; ; } else
{ sys::cas_flag tmp = initialized; sys::MemoryFence(); while
(tmp != 2) { tmp = initialized; sys::MemoryFence(); } } ; }
9969char ScalarEvolutionWrapperPass::ID = 0;
9970
9971ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
9972 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
9973}
9974
9975bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) {
9976 SE.reset(new ScalarEvolution(
9977 F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
9978 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
9979 getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
9980 getAnalysis<LoopInfoWrapperPass>().getLoopInfo()));
9981 return false;
9982}
9983
9984void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
9985
9986void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
9987 SE->print(OS);
9988}
9989
9990void ScalarEvolutionWrapperPass::verifyAnalysis() const {
9991 if (!VerifySCEV)
9992 return;
9993
9994 SE->verify();
9995}
9996
9997void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
9998 AU.setPreservesAll();
9999 AU.addRequiredTransitive<AssumptionCacheTracker>();
10000 AU.addRequiredTransitive<LoopInfoWrapperPass>();
10001 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
10002 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
10003}
10004
10005const SCEVPredicate *
10006ScalarEvolution::getEqualPredicate(const SCEVUnknown *LHS,
10007 const SCEVConstant *RHS) {
10008 FoldingSetNodeID ID;
10009 // Unique this node based on the arguments
10010 ID.AddInteger(SCEVPredicate::P_Equal);
10011 ID.AddPointer(LHS);
10012 ID.AddPointer(RHS);
10013 void *IP = nullptr;
10014 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
10015 return S;
10016 SCEVEqualPredicate *Eq = new (SCEVAllocator)
10017 SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS);
10018 UniquePreds.InsertNode(Eq, IP);
10019 return Eq;
10020}
10021
10022const SCEVPredicate *ScalarEvolution::getWrapPredicate(
10023 const SCEVAddRecExpr *AR,
10024 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
10025 FoldingSetNodeID ID;
10026 // Unique this node based on the arguments
10027 ID.AddInteger(SCEVPredicate::P_Wrap);
10028 ID.AddPointer(AR);
10029 ID.AddInteger(AddedFlags);
10030 void *IP = nullptr;
10031 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
10032 return S;
10033 auto *OF = new (SCEVAllocator)
10034 SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
10035 UniquePreds.InsertNode(OF, IP);
10036 return OF;
10037}
10038
10039namespace {
10040
10041class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
10042public:
10043 // Rewrites \p S in the context of a loop L and the predicate A.
10044 // If Assume is true, rewrite is free to add further predicates to A
10045 // such that the result will be an AddRecExpr.
10046 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
10047 SCEVUnionPredicate &A, bool Assume) {
10048 SCEVPredicateRewriter Rewriter(L, SE, A, Assume);
10049 return Rewriter.visit(S);
10050 }
10051
10052 SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
10053 SCEVUnionPredicate &P, bool Assume)
10054 : SCEVRewriteVisitor(SE), P(P), L(L), Assume(Assume) {}
10055
10056 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
10057 auto ExprPreds = P.getPredicatesForExpr(Expr);
10058 for (auto *Pred : ExprPreds)
10059 if (const auto *IPred = dyn_cast<const SCEVEqualPredicate>(Pred))
10060 if (IPred->getLHS() == Expr)
10061 return IPred->getRHS();
10062
10063 return Expr;
10064 }
10065
10066 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
10067 const SCEV *Operand = visit(Expr->getOperand());
10068 const SCEVAddRecExpr *AR = dyn_cast<const SCEVAddRecExpr>(Operand);
10069 if (AR && AR->getLoop() == L && AR->isAffine()) {
10070 // This couldn't be folded because the operand didn't have the nuw
10071 // flag. Add the nusw flag as an assumption that we could make.
10072 const SCEV *Step = AR->getStepRecurrence(SE);
10073 Type *Ty = Expr->getType();
10074 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
10075 return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
10076 SE.getSignExtendExpr(Step, Ty), L,
10077 AR->getNoWrapFlags());
10078 }
10079 return SE.getZeroExtendExpr(Operand, Expr->getType());
10080 }
10081
10082 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
10083 const SCEV *Operand = visit(Expr->getOperand());
10084 const SCEVAddRecExpr *AR = dyn_cast<const SCEVAddRecExpr>(Operand);
10085 if (AR && AR->getLoop() == L && AR->isAffine()) {
10086 // This couldn't be folded because the operand didn't have the nsw
10087 // flag. Add the nssw flag as an assumption that we could make.
10088 const SCEV *Step = AR->getStepRecurrence(SE);
10089 Type *Ty = Expr->getType();
10090 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
10091 return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
10092 SE.getSignExtendExpr(Step, Ty), L,
10093 AR->getNoWrapFlags());
10094 }
10095 return SE.getSignExtendExpr(Operand, Expr->getType());
10096 }
10097
10098private:
10099 bool addOverflowAssumption(const SCEVAddRecExpr *AR,
10100 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
10101 auto *A = SE.getWrapPredicate(AR, AddedFlags);
10102 if (!Assume) {
10103 // Check if we've already made this assumption.
10104 if (P.implies(A))
10105 return true;
10106 return false;
10107 }
10108 P.add(A);
10109 return true;
10110 }
10111
10112 SCEVUnionPredicate &P;
10113 const Loop *L;
10114 bool Assume;
10115};
10116} // end anonymous namespace
10117
10118const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
10119 SCEVUnionPredicate &Preds) {
10120 return SCEVPredicateRewriter::rewrite(S, L, *this, Preds, false);
10121}
10122
10123const SCEVAddRecExpr *
10124ScalarEvolution::convertSCEVToAddRecWithPredicates(const SCEV *S, const Loop *L,
10125 SCEVUnionPredicate &Preds) {
10126 SCEVUnionPredicate TransformPreds;
10127 S = SCEVPredicateRewriter::rewrite(S, L, *this, TransformPreds, true);
10128 auto *AddRec = dyn_cast<SCEVAddRecExpr>(S);
10129
10130 if (!AddRec)
10131 return nullptr;
10132
10133 // Since the transformation was successful, we can now transfer the SCEV
10134 // predicates.
10135 Preds.add(&TransformPreds);
10136 return AddRec;
10137}
10138
10139/// SCEV predicates
10140SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
10141 SCEVPredicateKind Kind)
10142 : FastID(ID), Kind(Kind) {}
10143
10144SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID,
10145 const SCEVUnknown *LHS,
10146 const SCEVConstant *RHS)
10147 : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) {}
10148
10149bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const {
10150 const auto *Op = dyn_cast<const SCEVEqualPredicate>(N);
10151
10152 if (!Op)
10153 return false;
10154
10155 return Op->LHS == LHS && Op->RHS == RHS;
10156}
10157
10158bool SCEVEqualPredicate::isAlwaysTrue() const { return false; }
10159
10160const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; }
10161
10162void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
10163 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
10164}
10165
10166SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
10167 const SCEVAddRecExpr *AR,
10168 IncrementWrapFlags Flags)
10169 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
10170
10171const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
10172
10173bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
10174 const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
10175
10176 return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
10177}
10178
10179bool SCEVWrapPredicate::isAlwaysTrue() const {
10180 SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
10181 IncrementWrapFlags IFlags = Flags;
10182
10183 if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
10184 IFlags = clearFlags(IFlags, IncrementNSSW);
10185
10186 return IFlags == IncrementAnyWrap;
10187}
10188
10189void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
10190 OS.indent(Depth) << *getExpr() << " Added Flags: ";
10191 if (SCEVWrapPredicate::IncrementNUSW & getFlags())
10192 OS << "<nusw>";
10193 if (SCEVWrapPredicate::IncrementNSSW & getFlags())
10194 OS << "<nssw>";
10195 OS << "\n";
10196}
10197
10198SCEVWrapPredicate::IncrementWrapFlags
10199SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
10200 ScalarEvolution &SE) {
10201 IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
10202 SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
10203
10204 // We can safely transfer the NSW flag as NSSW.
10205 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
10206 ImpliedFlags = IncrementNSSW;
10207
10208 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
10209 // If the increment is positive, the SCEV NUW flag will also imply the
10210 // WrapPredicate NUSW flag.
10211 if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
10212 if (Step->getValue()->getValue().isNonNegative())
10213 ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
10214 }
10215
10216 return ImpliedFlags;
10217}
10218
10219/// Union predicates don't get cached so create a dummy set ID for it.
10220SCEVUnionPredicate::SCEVUnionPredicate()
10221 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
10222
10223bool SCEVUnionPredicate::isAlwaysTrue() const {
10224 return all_of(Preds,
10225 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
10226}
10227
10228ArrayRef<const SCEVPredicate *>
10229SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) {
10230 auto I = SCEVToPreds.find(Expr);
10231 if (I == SCEVToPreds.end())
10232 return ArrayRef<const SCEVPredicate *>();
10233 return I->second;
10234}
10235
10236bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const {
10237 if (const auto *Set = dyn_cast<const SCEVUnionPredicate>(N))
10238 return all_of(Set->Preds,
10239 [this](const SCEVPredicate *I) { return this->implies(I); });
10240
10241 auto ScevPredsIt = SCEVToPreds.find(N->getExpr());
10242 if (ScevPredsIt == SCEVToPreds.end())
10243 return false;
10244 auto &SCEVPreds = ScevPredsIt->second;
10245
10246 return any_of(SCEVPreds,
10247 [N](const SCEVPredicate *I) { return I->implies(N); });
10248}
10249
10250const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; }
10251
10252void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
10253 for (auto Pred : Preds)
10254 Pred->print(OS, Depth);
10255}
10256
10257void SCEVUnionPredicate::add(const SCEVPredicate *N) {
10258 if (const auto *Set = dyn_cast<const SCEVUnionPredicate>(N)) {
10259 for (auto Pred : Set->Preds)
10260 add(Pred);
10261 return;
10262 }
10263
10264 if (implies(N))
10265 return;
10266
10267 const SCEV *Key = N->getExpr();
10268 assert(Key && "Only SCEVUnionPredicate doesn't have an "((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!"
) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 10269, __PRETTY_FUNCTION__))
10269 " associated expression!")((Key && "Only SCEVUnionPredicate doesn't have an " " associated expression!"
) ? static_cast<void> (0) : __assert_fail ("Key && \"Only SCEVUnionPredicate doesn't have an \" \" associated expression!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn267387/lib/Analysis/ScalarEvolution.cpp"
, 10269, __PRETTY_FUNCTION__));
10270
10271 SCEVToPreds[Key].push_back(N);
10272 Preds.push_back(N);
10273}
10274
10275PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
10276 Loop &L)
10277 : SE(SE), L(L), Generation(0), BackedgeCount(nullptr) {}
10278
10279const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
10280 const SCEV *Expr = SE.getSCEV(V);
10281 RewriteEntry &Entry = RewriteMap[Expr];
10282
10283 // If we already have an entry and the version matches, return it.
10284 if (Entry.second && Generation == Entry.first)
10285 return Entry.second;
10286
10287 // We found an entry but it's stale. Rewrite the stale entry
10288 // acording to the current predicate.
10289 if (Entry.second)
10290 Expr = Entry.second;
10291
10292 const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds);
10293 Entry = {Generation, NewSCEV};
10294
10295 return NewSCEV;
10296}
10297
10298const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
10299 if (!BackedgeCount) {
10300 SCEVUnionPredicate BackedgePred;
10301 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred);
10302 addPredicate(BackedgePred);
10303 }
10304 return BackedgeCount;
10305}
10306
10307void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
10308 if (Preds.implies(&Pred))
10309 return;
10310 Preds.add(&Pred);
10311 updateGeneration();
10312}
10313
10314const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const {
10315 return Preds;
10316}
10317
10318void PredicatedScalarEvolution::updateGeneration() {
10319 // If the generation number wrapped recompute everything.
10320 if (++Generation == 0) {
10321 for (auto &II : RewriteMap) {
10322 const SCEV *Rewritten = II.second.second;
10323 II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)};
10324 }
10325 }
10326}
10327
10328void PredicatedScalarEvolution::setNoOverflow(
10329 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
10330 const SCEV *Expr = getSCEV(V);
10331 const auto *AR = cast<SCEVAddRecExpr>(Expr);
10332
10333 auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
10334
10335 // Clear the statically implied flags.
10336 Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
10337 addPredicate(*SE.getWrapPredicate(AR, Flags));
10338
10339 auto II = FlagsMap.insert({V, Flags});
10340 if (!II.second)
10341 II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
10342}
10343
10344bool PredicatedScalarEvolution::hasNoOverflow(
10345 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
10346 const SCEV *Expr = getSCEV(V);
10347 const auto *AR = cast<SCEVAddRecExpr>(Expr);
10348
10349 Flags = SCEVWrapPredicate::clearFlags(
10350 Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
10351
10352 auto II = FlagsMap.find(V);
10353
10354 if (II != FlagsMap.end())
10355 Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
10356
10357 return Flags == SCEVWrapPredicate::IncrementAnyWrap;
10358}
10359
10360const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) {
10361 const SCEV *Expr = this->getSCEV(V);
10362 auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, Preds);
10363
10364 if (!New)
10365 return nullptr;
10366
10367 updateGeneration();
10368 RewriteMap[SE.getSCEV(V)] = {Generation, New};
10369 return New;
10370}
10371
10372PredicatedScalarEvolution::PredicatedScalarEvolution(
10373 const PredicatedScalarEvolution &Init)
10374 : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds),
10375 Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) {
10376 for (auto I = Init.FlagsMap.begin(), E = Init.FlagsMap.end(); I != E; ++I)
10377 FlagsMap.insert(*I);
10378}
10379
10380void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
10381 // For each block.
10382 for (auto *BB : L.getBlocks())
10383 for (auto &I : *BB) {
10384 if (!SE.isSCEVable(I.getType()))
10385 continue;
10386
10387 auto *Expr = SE.getSCEV(&I);
10388 auto II = RewriteMap.find(Expr);
10389
10390 if (II == RewriteMap.end())
10391 continue;
10392
10393 // Don't print things that are not interesting.
10394 if (II->second.second == Expr)
10395 continue;
10396
10397 OS.indent(Depth) << "[PSE]" << I << ":\n";
10398 OS.indent(Depth + 2) << *Expr << "\n";
10399 OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
10400 }
10401}