Bug Summary

File:lib/Analysis/ScalarEvolution.cpp
Location:line 8816, column 15
Description:Value stored to 'MaxBECount' during its initialization is never read

Annotated Source Code

1//===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains the implementation of the scalar evolution analysis
11// engine, which is used primarily to analyze expressions involving induction
12// variables in loops.
13//
14// There are several aspects to this library. First is the representation of
15// scalar expressions, which are represented as subclasses of the SCEV class.
16// These classes are used to represent certain types of subexpressions that we
17// can handle. We only create one SCEV of a particular shape, so
18// pointer-comparisons for equality are legal.
19//
20// One important aspect of the SCEV objects is that they are never cyclic, even
21// if there is a cycle in the dataflow for an expression (ie, a PHI node). If
22// the PHI node is one of the idioms that we can represent (e.g., a polynomial
23// recurrence) then we represent it directly as a recurrence node, otherwise we
24// represent it as a SCEVUnknown node.
25//
26// In addition to being able to represent expressions of various types, we also
27// have folders that are used to build the *canonical* representation for a
28// particular expression. These folders are capable of using a variety of
29// rewrite rules to simplify the expressions.
30//
31// Once the folders are defined, we can implement the more interesting
32// higher-level code, such as the code that recognizes PHI nodes of various
33// types, computes the execution count of a loop, etc.
34//
35// TODO: We should use these routines and value representations to implement
36// dependence analysis!
37//
38//===----------------------------------------------------------------------===//
39//
40// There are several good references for the techniques used in this analysis.
41//
42// Chains of recurrences -- a method to expedite the evaluation
43// of closed-form functions
44// Olaf Bachmann, Paul S. Wang, Eugene V. Zima
45//
46// On computational properties of chains of recurrences
47// Eugene V. Zima
48//
49// Symbolic Evaluation of Chains of Recurrences for Loop Optimization
50// Robert A. van Engelen
51//
52// Efficient Symbolic Analysis for Optimizing Compilers
53// Robert A. van Engelen
54//
55// Using the chains of recurrences algebra for data dependence testing and
56// induction variable substitution
57// MS Thesis, Johnie Birch
58//
59//===----------------------------------------------------------------------===//
60
61#include "llvm/Analysis/ScalarEvolution.h"
62#include "llvm/ADT/Optional.h"
63#include "llvm/ADT/STLExtras.h"
64#include "llvm/ADT/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 EXPENSIVE_CHECKS 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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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~svn271111/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
1526 // Normally, in the cases we can prove no-overflow via a
1527 // backedge guarding condition, we can also compute a backedge
1528 // taken count for the loop. The exceptions are assumptions and
1529 // guards present in the loop -- SCEV is not great at exploiting
1530 // these to compute max backedge taken counts, but can still use
1531 // these to prove lack of overflow. Use this fact to avoid
1532 // doing extra work that may not pay off.
1533 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1534 !AC.assumptions().empty()) {
1535 // If the backedge is guarded by a comparison with the pre-inc
1536 // value the addrec is safe. Also, if the entry is guarded by
1537 // a comparison with the start value and the backedge is
1538 // guarded by a comparison with the post-inc value, the addrec
1539 // is safe.
1540 if (isKnownPositive(Step)) {
1541 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1542 getUnsignedRange(Step).getUnsignedMax());
1543 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1544 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
1545 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
1546 AR->getPostIncExpr(*this), N))) {
1547 // Cache knowledge of AR NUW, which is propagated to this
1548 // AddRec.
1549 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1550 // Return the expression with the addrec on the outside.
1551 return getAddRecExpr(
1552 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1553 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1554 }
1555 } else if (isKnownNegative(Step)) {
1556 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1557 getSignedRange(Step).getSignedMin());
1558 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1559 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) &&
1560 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
1561 AR->getPostIncExpr(*this), N))) {
1562 // Cache knowledge of AR NW, which is propagated to this
1563 // AddRec. Negative step causes unsigned wrap, but it
1564 // still can't self-wrap.
1565 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1566 // Return the expression with the addrec on the outside.
1567 return getAddRecExpr(
1568 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1569 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1570 }
1571 }
1572 }
1573
1574 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1575 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1576 return getAddRecExpr(
1577 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this),
1578 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1579 }
1580 }
1581
1582 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1583 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1584 if (SA->hasNoUnsignedWrap()) {
1585 // If the addition does not unsign overflow then we can, by definition,
1586 // commute the zero extension with the addition operation.
1587 SmallVector<const SCEV *, 4> Ops;
1588 for (const auto *Op : SA->operands())
1589 Ops.push_back(getZeroExtendExpr(Op, Ty));
1590 return getAddExpr(Ops, SCEV::FlagNUW);
1591 }
1592 }
1593
1594 // The cast wasn't folded; create an explicit cast node.
1595 // Recompute the insert position, as it may have been invalidated.
1596 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1597 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1598 Op, Ty);
1599 UniqueSCEVs.InsertNode(S, IP);
1600 return S;
1601}
1602
1603const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
1604 Type *Ty) {
1605 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1606, __PRETTY_FUNCTION__))
1606 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1606, __PRETTY_FUNCTION__))
;
1607 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1608, __PRETTY_FUNCTION__))
1608 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1608, __PRETTY_FUNCTION__))
;
1609 Ty = getEffectiveSCEVType(Ty);
1610
1611 // Fold if the operand is constant.
1612 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1613 return getConstant(
1614 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1615
1616 // sext(sext(x)) --> sext(x)
1617 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1618 return getSignExtendExpr(SS->getOperand(), Ty);
1619
1620 // sext(zext(x)) --> zext(x)
1621 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1622 return getZeroExtendExpr(SZ->getOperand(), Ty);
1623
1624 // Before doing any expensive analysis, check to see if we've already
1625 // computed a SCEV for this Op and Ty.
1626 FoldingSetNodeID ID;
1627 ID.AddInteger(scSignExtend);
1628 ID.AddPointer(Op);
1629 ID.AddPointer(Ty);
1630 void *IP = nullptr;
1631 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1632
1633 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1634 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1635 // It's possible the bits taken off by the truncate were all sign bits. If
1636 // so, we should be able to simplify this further.
1637 const SCEV *X = ST->getOperand();
1638 ConstantRange CR = getSignedRange(X);
1639 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1640 unsigned NewBits = getTypeSizeInBits(Ty);
1641 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1642 CR.sextOrTrunc(NewBits)))
1643 return getTruncateOrSignExtend(X, Ty);
1644 }
1645
1646 // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2
1647 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1648 if (SA->getNumOperands() == 2) {
1649 auto *SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0));
1650 auto *SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1));
1651 if (SMul && SC1) {
1652 if (auto *SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) {
1653 const APInt &C1 = SC1->getAPInt();
1654 const APInt &C2 = SC2->getAPInt();
1655 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
1656 C2.ugt(C1) && C2.isPowerOf2())
1657 return getAddExpr(getSignExtendExpr(SC1, Ty),
1658 getSignExtendExpr(SMul, Ty));
1659 }
1660 }
1661 }
1662
1663 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1664 if (SA->hasNoSignedWrap()) {
1665 // If the addition does not sign overflow then we can, by definition,
1666 // commute the sign extension with the addition operation.
1667 SmallVector<const SCEV *, 4> Ops;
1668 for (const auto *Op : SA->operands())
1669 Ops.push_back(getSignExtendExpr(Op, Ty));
1670 return getAddExpr(Ops, SCEV::FlagNSW);
1671 }
1672 }
1673 // If the input value is a chrec scev, and we can prove that the value
1674 // did not overflow the old, smaller, value, we can sign extend all of the
1675 // operands (often constants). This allows analysis of something like
1676 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1677 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1678 if (AR->isAffine()) {
1679 const SCEV *Start = AR->getStart();
1680 const SCEV *Step = AR->getStepRecurrence(*this);
1681 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1682 const Loop *L = AR->getLoop();
1683
1684 if (!AR->hasNoSignedWrap()) {
1685 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1686 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1687 }
1688
1689 // If we have special knowledge that this addrec won't overflow,
1690 // we don't need to do any further analysis.
1691 if (AR->hasNoSignedWrap())
1692 return getAddRecExpr(
1693 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1694 getSignExtendExpr(Step, Ty), L, SCEV::FlagNSW);
1695
1696 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1697 // Note that this serves two purposes: It filters out loops that are
1698 // simply not analyzable, and it covers the case where this code is
1699 // being called from within backedge-taken count analysis, such that
1700 // attempting to ask for the backedge-taken count would likely result
1701 // in infinite recursion. In the later case, the analysis code will
1702 // cope with a conservative value, and it will take care to purge
1703 // that value once it has finished.
1704 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1705 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1706 // Manually compute the final value for AR, checking for
1707 // overflow.
1708
1709 // Check whether the backedge-taken count can be losslessly casted to
1710 // the addrec's type. The count is always unsigned.
1711 const SCEV *CastedMaxBECount =
1712 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1713 const SCEV *RecastedMaxBECount =
1714 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1715 if (MaxBECount == RecastedMaxBECount) {
1716 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1717 // Check whether Start+Step*MaxBECount has no signed overflow.
1718 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
1719 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul), WideTy);
1720 const SCEV *WideStart = getSignExtendExpr(Start, WideTy);
1721 const SCEV *WideMaxBECount =
1722 getZeroExtendExpr(CastedMaxBECount, WideTy);
1723 const SCEV *OperandExtendedAdd =
1724 getAddExpr(WideStart,
1725 getMulExpr(WideMaxBECount,
1726 getSignExtendExpr(Step, WideTy)));
1727 if (SAdd == OperandExtendedAdd) {
1728 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1729 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1730 // Return the expression with the addrec on the outside.
1731 return getAddRecExpr(
1732 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1733 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1734 }
1735 // Similar to above, only this time treat the step value as unsigned.
1736 // This covers loops that count up with an unsigned step.
1737 OperandExtendedAdd =
1738 getAddExpr(WideStart,
1739 getMulExpr(WideMaxBECount,
1740 getZeroExtendExpr(Step, WideTy)));
1741 if (SAdd == OperandExtendedAdd) {
1742 // If AR wraps around then
1743 //
1744 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
1745 // => SAdd != OperandExtendedAdd
1746 //
1747 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
1748 // (SAdd == OperandExtendedAdd => AR is NW)
1749
1750 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1751
1752 // Return the expression with the addrec on the outside.
1753 return getAddRecExpr(
1754 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1755 getZeroExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1756 }
1757 }
1758 }
1759
1760 // Normally, in the cases we can prove no-overflow via a
1761 // backedge guarding condition, we can also compute a backedge
1762 // taken count for the loop. The exceptions are assumptions and
1763 // guards present in the loop -- SCEV is not great at exploiting
1764 // these to compute max backedge taken counts, but can still use
1765 // these to prove lack of overflow. Use this fact to avoid
1766 // doing extra work that may not pay off.
1767
1768 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1769 !AC.assumptions().empty()) {
1770 // If the backedge is guarded by a comparison with the pre-inc
1771 // value the addrec is safe. Also, if the entry is guarded by
1772 // a comparison with the start value and the backedge is
1773 // guarded by a comparison with the post-inc value, the addrec
1774 // is safe.
1775 ICmpInst::Predicate Pred;
1776 const SCEV *OverflowLimit =
1777 getSignedOverflowLimitForStep(Step, &Pred, this);
1778 if (OverflowLimit &&
1779 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
1780 (isLoopEntryGuardedByCond(L, Pred, Start, OverflowLimit) &&
1781 isLoopBackedgeGuardedByCond(L, Pred, AR->getPostIncExpr(*this),
1782 OverflowLimit)))) {
1783 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
1784 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1785 return getAddRecExpr(
1786 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1787 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1788 }
1789 }
1790
1791 // If Start and Step are constants, check if we can apply this
1792 // transformation:
1793 // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2
1794 auto *SC1 = dyn_cast<SCEVConstant>(Start);
1795 auto *SC2 = dyn_cast<SCEVConstant>(Step);
1796 if (SC1 && SC2) {
1797 const APInt &C1 = SC1->getAPInt();
1798 const APInt &C2 = SC2->getAPInt();
1799 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) &&
1800 C2.isPowerOf2()) {
1801 Start = getSignExtendExpr(Start, Ty);
1802 const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L,
1803 AR->getNoWrapFlags());
1804 return getAddExpr(Start, getSignExtendExpr(NewAR, Ty));
1805 }
1806 }
1807
1808 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
1809 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1810 return getAddRecExpr(
1811 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this),
1812 getSignExtendExpr(Step, Ty), L, AR->getNoWrapFlags());
1813 }
1814 }
1815
1816 // If the input value is provably positive and we could not simplify
1817 // away the sext build a zext instead.
1818 if (isKnownNonNegative(Op))
1819 return getZeroExtendExpr(Op, Ty);
1820
1821 // The cast wasn't folded; create an explicit cast node.
1822 // Recompute the insert position, as it may have been invalidated.
1823 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1824 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1825 Op, Ty);
1826 UniqueSCEVs.InsertNode(S, IP);
1827 return S;
1828}
1829
1830/// getAnyExtendExpr - Return a SCEV for the given operand extended with
1831/// unspecified bits out to the given type.
1832///
1833const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
1834 Type *Ty) {
1835 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1836, __PRETTY_FUNCTION__))
1836 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1836, __PRETTY_FUNCTION__))
;
1837 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1838, __PRETTY_FUNCTION__))
1838 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1838, __PRETTY_FUNCTION__))
;
1839 Ty = getEffectiveSCEVType(Ty);
1840
1841 // Sign-extend negative constants.
1842 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1843 if (SC->getAPInt().isNegative())
1844 return getSignExtendExpr(Op, Ty);
1845
1846 // Peel off a truncate cast.
1847 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
1848 const SCEV *NewOp = T->getOperand();
1849 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
1850 return getAnyExtendExpr(NewOp, Ty);
1851 return getTruncateOrNoop(NewOp, Ty);
1852 }
1853
1854 // Next try a zext cast. If the cast is folded, use it.
1855 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
1856 if (!isa<SCEVZeroExtendExpr>(ZExt))
1857 return ZExt;
1858
1859 // Next try a sext cast. If the cast is folded, use it.
1860 const SCEV *SExt = getSignExtendExpr(Op, Ty);
1861 if (!isa<SCEVSignExtendExpr>(SExt))
1862 return SExt;
1863
1864 // Force the cast to be folded into the operands of an addrec.
1865 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
1866 SmallVector<const SCEV *, 4> Ops;
1867 for (const SCEV *Op : AR->operands())
1868 Ops.push_back(getAnyExtendExpr(Op, Ty));
1869 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
1870 }
1871
1872 // If the expression is obviously signed, use the sext cast value.
1873 if (isa<SCEVSMaxExpr>(Op))
1874 return SExt;
1875
1876 // Absent any other information, use the zext cast value.
1877 return ZExt;
1878}
1879
1880/// CollectAddOperandsWithScales - Process the given Ops list, which is
1881/// a list of operands to be added under the given scale, update the given
1882/// map. This is a helper function for getAddRecExpr. As an example of
1883/// what it does, given a sequence of operands that would form an add
1884/// expression like this:
1885///
1886/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
1887///
1888/// where A and B are constants, update the map with these values:
1889///
1890/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
1891///
1892/// and add 13 + A*B*29 to AccumulatedConstant.
1893/// This will allow getAddRecExpr to produce this:
1894///
1895/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
1896///
1897/// This form often exposes folding opportunities that are hidden in
1898/// the original operand list.
1899///
1900/// Return true iff it appears that any interesting folding opportunities
1901/// may be exposed. This helps getAddRecExpr short-circuit extra work in
1902/// the common case where no interesting opportunities are present, and
1903/// is also used as a check to avoid infinite recursion.
1904///
1905static bool
1906CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
1907 SmallVectorImpl<const SCEV *> &NewOps,
1908 APInt &AccumulatedConstant,
1909 const SCEV *const *Ops, size_t NumOperands,
1910 const APInt &Scale,
1911 ScalarEvolution &SE) {
1912 bool Interesting = false;
1913
1914 // Iterate over the add operands. They are sorted, with constants first.
1915 unsigned i = 0;
1916 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
1917 ++i;
1918 // Pull a buried constant out to the outside.
1919 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
1920 Interesting = true;
1921 AccumulatedConstant += Scale * C->getAPInt();
1922 }
1923
1924 // Next comes everything else. We're especially interested in multiplies
1925 // here, but they're in the middle, so just visit the rest with one loop.
1926 for (; i != NumOperands; ++i) {
1927 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
1928 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
1929 APInt NewScale =
1930 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
1931 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
1932 // A multiplication of a constant with another add; recurse.
1933 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
1934 Interesting |=
1935 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
1936 Add->op_begin(), Add->getNumOperands(),
1937 NewScale, SE);
1938 } else {
1939 // A multiplication of a constant with some other value. Update
1940 // the map.
1941 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
1942 const SCEV *Key = SE.getMulExpr(MulOps);
1943 auto Pair = M.insert({Key, NewScale});
1944 if (Pair.second) {
1945 NewOps.push_back(Pair.first->first);
1946 } else {
1947 Pair.first->second += NewScale;
1948 // The map already had an entry for this value, which may indicate
1949 // a folding opportunity.
1950 Interesting = true;
1951 }
1952 }
1953 } else {
1954 // An ordinary operand. Update the map.
1955 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
1956 M.insert({Ops[i], Scale});
1957 if (Pair.second) {
1958 NewOps.push_back(Pair.first->first);
1959 } else {
1960 Pair.first->second += Scale;
1961 // The map already had an entry for this value, which may indicate
1962 // a folding opportunity.
1963 Interesting = true;
1964 }
1965 }
1966 }
1967
1968 return Interesting;
1969}
1970
1971// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
1972// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
1973// can't-overflow flags for the operation if possible.
1974static SCEV::NoWrapFlags
1975StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
1976 const SmallVectorImpl<const SCEV *> &Ops,
1977 SCEV::NoWrapFlags Flags) {
1978 using namespace std::placeholders;
1979 typedef OverflowingBinaryOperator OBO;
1980
1981 bool CanAnalyze =
1982 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
1983 (void)CanAnalyze;
1984 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 1984, __PRETTY_FUNCTION__))
;
1985
1986 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
1987 SCEV::NoWrapFlags SignOrUnsignWrap =
1988 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
1989
1990 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
1991 auto IsKnownNonNegative = [&](const SCEV *S) {
1992 return SE->isKnownNonNegative(S);
1993 };
1994
1995 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
1996 Flags =
1997 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
1998
1999 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2000
2001 if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr &&
2002 Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) {
2003
2004 // (A + C) --> (A + C)<nsw> if the addition does not sign overflow
2005 // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow
2006
2007 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2008 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2009 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2010 Instruction::Add, C, OBO::NoSignedWrap);
2011 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2012 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2013 }
2014 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2015 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2016 Instruction::Add, C, OBO::NoUnsignedWrap);
2017 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2018 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2019 }
2020 }
2021
2022 return Flags;
2023}
2024
2025/// getAddExpr - Get a canonical add expression, or something simpler if
2026/// possible.
2027const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2028 SCEV::NoWrapFlags Flags) {
2029 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2030, __PRETTY_FUNCTION__))
2030 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2030, __PRETTY_FUNCTION__))
;
2031 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2031, __PRETTY_FUNCTION__))
;
2032 if (Ops.size() == 1) return Ops[0];
2033#ifndef NDEBUG
2034 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2035 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2036 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2037, __PRETTY_FUNCTION__))
2037 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2037, __PRETTY_FUNCTION__))
;
2038#endif
2039
2040 // Sort by complexity, this groups all similar expression types together.
2041 GroupByComplexity(Ops, &LI);
2042
2043 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2044
2045 // If there are any constants, fold them together.
2046 unsigned Idx = 0;
2047 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2048 ++Idx;
2049 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2049, __PRETTY_FUNCTION__))
;
2050 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2051 // We found two constants, fold them together!
2052 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2053 if (Ops.size() == 2) return Ops[0];
2054 Ops.erase(Ops.begin()+1); // Erase the folded element
2055 LHSC = cast<SCEVConstant>(Ops[0]);
2056 }
2057
2058 // If we are left with a constant zero being added, strip it off.
2059 if (LHSC->getValue()->isZero()) {
2060 Ops.erase(Ops.begin());
2061 --Idx;
2062 }
2063
2064 if (Ops.size() == 1) return Ops[0];
2065 }
2066
2067 // Okay, check to see if the same value occurs in the operand list more than
2068 // once. If so, merge them together into an multiply expression. Since we
2069 // sorted the list, these values are required to be adjacent.
2070 Type *Ty = Ops[0]->getType();
2071 bool FoundMatch = false;
2072 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2073 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2074 // Scan ahead to count how many equal operands there are.
2075 unsigned Count = 2;
2076 while (i+Count != e && Ops[i+Count] == Ops[i])
2077 ++Count;
2078 // Merge the values into a multiply.
2079 const SCEV *Scale = getConstant(Ty, Count);
2080 const SCEV *Mul = getMulExpr(Scale, Ops[i]);
2081 if (Ops.size() == Count)
2082 return Mul;
2083 Ops[i] = Mul;
2084 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2085 --i; e -= Count - 1;
2086 FoundMatch = true;
2087 }
2088 if (FoundMatch)
2089 return getAddExpr(Ops, Flags);
2090
2091 // Check for truncates. If all the operands are truncated from the same
2092 // type, see if factoring out the truncate would permit the result to be
2093 // folded. eg., trunc(x) + m*trunc(n) --> trunc(x + trunc(m)*n)
2094 // if the contents of the resulting outer trunc fold to something simple.
2095 for (; Idx < Ops.size() && isa<SCEVTruncateExpr>(Ops[Idx]); ++Idx) {
2096 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(Ops[Idx]);
2097 Type *DstType = Trunc->getType();
2098 Type *SrcType = Trunc->getOperand()->getType();
2099 SmallVector<const SCEV *, 8> LargeOps;
2100 bool Ok = true;
2101 // Check all the operands to see if they can be represented in the
2102 // source type of the truncate.
2103 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2104 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2105 if (T->getOperand()->getType() != SrcType) {
2106 Ok = false;
2107 break;
2108 }
2109 LargeOps.push_back(T->getOperand());
2110 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2111 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2112 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2113 SmallVector<const SCEV *, 8> LargeMulOps;
2114 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2115 if (const SCEVTruncateExpr *T =
2116 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2117 if (T->getOperand()->getType() != SrcType) {
2118 Ok = false;
2119 break;
2120 }
2121 LargeMulOps.push_back(T->getOperand());
2122 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2123 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2124 } else {
2125 Ok = false;
2126 break;
2127 }
2128 }
2129 if (Ok)
2130 LargeOps.push_back(getMulExpr(LargeMulOps));
2131 } else {
2132 Ok = false;
2133 break;
2134 }
2135 }
2136 if (Ok) {
2137 // Evaluate the expression in the larger type.
2138 const SCEV *Fold = getAddExpr(LargeOps, Flags);
2139 // If it folds to something simple, use it. Otherwise, don't.
2140 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2141 return getTruncateExpr(Fold, DstType);
2142 }
2143 }
2144
2145 // Skip past any other cast SCEVs.
2146 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2147 ++Idx;
2148
2149 // If there are add operands they would be next.
2150 if (Idx < Ops.size()) {
2151 bool DeletedAdd = false;
2152 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2153 // If we have an add, expand the add operands onto the end of the operands
2154 // list.
2155 Ops.erase(Ops.begin()+Idx);
2156 Ops.append(Add->op_begin(), Add->op_end());
2157 DeletedAdd = true;
2158 }
2159
2160 // If we deleted at least one add, we added operands to the end of the list,
2161 // and they are not necessarily sorted. Recurse to resort and resimplify
2162 // any operands we just acquired.
2163 if (DeletedAdd)
2164 return getAddExpr(Ops);
2165 }
2166
2167 // Skip over the add expression until we get to a multiply.
2168 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2169 ++Idx;
2170
2171 // Check to see if there are any folding opportunities present with
2172 // operands multiplied by constant values.
2173 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2174 uint64_t BitWidth = getTypeSizeInBits(Ty);
2175 DenseMap<const SCEV *, APInt> M;
2176 SmallVector<const SCEV *, 8> NewOps;
2177 APInt AccumulatedConstant(BitWidth, 0);
2178 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2179 Ops.data(), Ops.size(),
2180 APInt(BitWidth, 1), *this)) {
2181 struct APIntCompare {
2182 bool operator()(const APInt &LHS, const APInt &RHS) const {
2183 return LHS.ult(RHS);
2184 }
2185 };
2186
2187 // Some interesting folding opportunity is present, so its worthwhile to
2188 // re-generate the operands list. Group the operands by constant scale,
2189 // to avoid multiplying by the same constant scale multiple times.
2190 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2191 for (const SCEV *NewOp : NewOps)
2192 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2193 // Re-generate the operands list.
2194 Ops.clear();
2195 if (AccumulatedConstant != 0)
2196 Ops.push_back(getConstant(AccumulatedConstant));
2197 for (auto &MulOp : MulOpLists)
2198 if (MulOp.first != 0)
2199 Ops.push_back(getMulExpr(getConstant(MulOp.first),
2200 getAddExpr(MulOp.second)));
2201 if (Ops.empty())
2202 return getZero(Ty);
2203 if (Ops.size() == 1)
2204 return Ops[0];
2205 return getAddExpr(Ops);
2206 }
2207 }
2208
2209 // If we are adding something to a multiply expression, make sure the
2210 // something is not already an operand of the multiply. If so, merge it into
2211 // the multiply.
2212 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2213 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2214 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2215 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2216 if (isa<SCEVConstant>(MulOpSCEV))
2217 continue;
2218 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2219 if (MulOpSCEV == Ops[AddOp]) {
2220 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2221 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2222 if (Mul->getNumOperands() != 2) {
2223 // If the multiply has more than two operands, we must get the
2224 // Y*Z term.
2225 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2226 Mul->op_begin()+MulOp);
2227 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2228 InnerMul = getMulExpr(MulOps);
2229 }
2230 const SCEV *One = getOne(Ty);
2231 const SCEV *AddOne = getAddExpr(One, InnerMul);
2232 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV);
2233 if (Ops.size() == 2) return OuterMul;
2234 if (AddOp < Idx) {
2235 Ops.erase(Ops.begin()+AddOp);
2236 Ops.erase(Ops.begin()+Idx-1);
2237 } else {
2238 Ops.erase(Ops.begin()+Idx);
2239 Ops.erase(Ops.begin()+AddOp-1);
2240 }
2241 Ops.push_back(OuterMul);
2242 return getAddExpr(Ops);
2243 }
2244
2245 // Check this multiply against other multiplies being added together.
2246 for (unsigned OtherMulIdx = Idx+1;
2247 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2248 ++OtherMulIdx) {
2249 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2250 // If MulOp occurs in OtherMul, we can fold the two multiplies
2251 // together.
2252 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2253 OMulOp != e; ++OMulOp)
2254 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2255 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2256 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2257 if (Mul->getNumOperands() != 2) {
2258 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2259 Mul->op_begin()+MulOp);
2260 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2261 InnerMul1 = getMulExpr(MulOps);
2262 }
2263 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2264 if (OtherMul->getNumOperands() != 2) {
2265 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2266 OtherMul->op_begin()+OMulOp);
2267 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2268 InnerMul2 = getMulExpr(MulOps);
2269 }
2270 const SCEV *InnerMulSum = getAddExpr(InnerMul1,InnerMul2);
2271 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum);
2272 if (Ops.size() == 2) return OuterMul;
2273 Ops.erase(Ops.begin()+Idx);
2274 Ops.erase(Ops.begin()+OtherMulIdx-1);
2275 Ops.push_back(OuterMul);
2276 return getAddExpr(Ops);
2277 }
2278 }
2279 }
2280 }
2281
2282 // If there are any add recurrences in the operands list, see if any other
2283 // added values are loop invariant. If so, we can fold them into the
2284 // recurrence.
2285 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2286 ++Idx;
2287
2288 // Scan over all recurrences, trying to fold loop invariants into them.
2289 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2290 // Scan all of the other operands to this add and add them to the vector if
2291 // they are loop invariant w.r.t. the recurrence.
2292 SmallVector<const SCEV *, 8> LIOps;
2293 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2294 const Loop *AddRecLoop = AddRec->getLoop();
2295 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2296 if (isLoopInvariant(Ops[i], AddRecLoop)) {
2297 LIOps.push_back(Ops[i]);
2298 Ops.erase(Ops.begin()+i);
2299 --i; --e;
2300 }
2301
2302 // If we found some loop invariants, fold them into the recurrence.
2303 if (!LIOps.empty()) {
2304 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2305 LIOps.push_back(AddRec->getStart());
2306
2307 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2308 AddRec->op_end());
2309 // This follows from the fact that the no-wrap flags on the outer add
2310 // expression are applicable on the 0th iteration, when the add recurrence
2311 // will be equal to its start value.
2312 AddRecOps[0] = getAddExpr(LIOps, Flags);
2313
2314 // Build the new addrec. Propagate the NUW and NSW flags if both the
2315 // outer add and the inner addrec are guaranteed to have no overflow.
2316 // Always propagate NW.
2317 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2318 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2319
2320 // If all of the other operands were loop invariant, we are done.
2321 if (Ops.size() == 1) return NewRec;
2322
2323 // Otherwise, add the folded AddRec by the non-invariant parts.
2324 for (unsigned i = 0;; ++i)
2325 if (Ops[i] == AddRec) {
2326 Ops[i] = NewRec;
2327 break;
2328 }
2329 return getAddExpr(Ops);
2330 }
2331
2332 // Okay, if there weren't any loop invariants to be folded, check to see if
2333 // there are multiple AddRec's with the same loop induction variable being
2334 // added together. If so, we can fold them.
2335 for (unsigned OtherIdx = Idx+1;
2336 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2337 ++OtherIdx)
2338 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2339 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2340 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2341 AddRec->op_end());
2342 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2343 ++OtherIdx)
2344 if (const auto *OtherAddRec = dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]))
2345 if (OtherAddRec->getLoop() == AddRecLoop) {
2346 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2347 i != e; ++i) {
2348 if (i >= AddRecOps.size()) {
2349 AddRecOps.append(OtherAddRec->op_begin()+i,
2350 OtherAddRec->op_end());
2351 break;
2352 }
2353 AddRecOps[i] = getAddExpr(AddRecOps[i],
2354 OtherAddRec->getOperand(i));
2355 }
2356 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2357 }
2358 // Step size has changed, so we cannot guarantee no self-wraparound.
2359 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2360 return getAddExpr(Ops);
2361 }
2362
2363 // Otherwise couldn't fold anything into this recurrence. Move onto the
2364 // next one.
2365 }
2366
2367 // Okay, it looks like we really DO need an add expr. Check to see if we
2368 // already have one, otherwise create a new one.
2369 FoldingSetNodeID ID;
2370 ID.AddInteger(scAddExpr);
2371 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2372 ID.AddPointer(Ops[i]);
2373 void *IP = nullptr;
2374 SCEVAddExpr *S =
2375 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2376 if (!S) {
2377 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2378 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2379 S = new (SCEVAllocator) SCEVAddExpr(ID.Intern(SCEVAllocator),
2380 O, Ops.size());
2381 UniqueSCEVs.InsertNode(S, IP);
2382 }
2383 S->setNoWrapFlags(Flags);
2384 return S;
2385}
2386
2387static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2388 uint64_t k = i*j;
2389 if (j > 1 && k / j != i) Overflow = true;
2390 return k;
2391}
2392
2393/// Compute the result of "n choose k", the binomial coefficient. If an
2394/// intermediate computation overflows, Overflow will be set and the return will
2395/// be garbage. Overflow is not cleared on absence of overflow.
2396static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2397 // We use the multiplicative formula:
2398 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2399 // At each iteration, we take the n-th term of the numeral and divide by the
2400 // (k-n)th term of the denominator. This division will always produce an
2401 // integral result, and helps reduce the chance of overflow in the
2402 // intermediate computations. However, we can still overflow even when the
2403 // final result would fit.
2404
2405 if (n == 0 || n == k) return 1;
2406 if (k > n) return 0;
2407
2408 if (k > n/2)
2409 k = n-k;
2410
2411 uint64_t r = 1;
2412 for (uint64_t i = 1; i <= k; ++i) {
2413 r = umul_ov(r, n-(i-1), Overflow);
2414 r /= i;
2415 }
2416 return r;
2417}
2418
2419/// Determine if any of the operands in this SCEV are a constant or if
2420/// any of the add or multiply expressions in this SCEV contain a constant.
2421static bool containsConstantSomewhere(const SCEV *StartExpr) {
2422 SmallVector<const SCEV *, 4> Ops;
2423 Ops.push_back(StartExpr);
2424 while (!Ops.empty()) {
2425 const SCEV *CurrentExpr = Ops.pop_back_val();
2426 if (isa<SCEVConstant>(*CurrentExpr))
2427 return true;
2428
2429 if (isa<SCEVAddExpr>(*CurrentExpr) || isa<SCEVMulExpr>(*CurrentExpr)) {
2430 const auto *CurrentNAry = cast<SCEVNAryExpr>(CurrentExpr);
2431 Ops.append(CurrentNAry->op_begin(), CurrentNAry->op_end());
2432 }
2433 }
2434 return false;
2435}
2436
2437/// getMulExpr - Get a canonical multiply expression, or something simpler if
2438/// possible.
2439const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2440 SCEV::NoWrapFlags Flags) {
2441 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2442, __PRETTY_FUNCTION__))
2442 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2442, __PRETTY_FUNCTION__))
;
2443 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2443, __PRETTY_FUNCTION__))
;
2444 if (Ops.size() == 1) return Ops[0];
2445#ifndef NDEBUG
2446 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2447 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2448 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2449, __PRETTY_FUNCTION__))
2449 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2449, __PRETTY_FUNCTION__))
;
2450#endif
2451
2452 // Sort by complexity, this groups all similar expression types together.
2453 GroupByComplexity(Ops, &LI);
2454
2455 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2456
2457 // If there are any constants, fold them together.
2458 unsigned Idx = 0;
2459 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2460
2461 // C1*(C2+V) -> C1*C2 + C1*V
2462 if (Ops.size() == 2)
2463 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2464 // If any of Add's ops are Adds or Muls with a constant,
2465 // apply this transformation as well.
2466 if (Add->getNumOperands() == 2)
2467 if (containsConstantSomewhere(Add))
2468 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0)),
2469 getMulExpr(LHSC, Add->getOperand(1)));
2470
2471 ++Idx;
2472 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2473 // We found two constants, fold them together!
2474 ConstantInt *Fold =
2475 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2476 Ops[0] = getConstant(Fold);
2477 Ops.erase(Ops.begin()+1); // Erase the folded element
2478 if (Ops.size() == 1) return Ops[0];
2479 LHSC = cast<SCEVConstant>(Ops[0]);
2480 }
2481
2482 // If we are left with a constant one being multiplied, strip it off.
2483 if (cast<SCEVConstant>(Ops[0])->getValue()->equalsInt(1)) {
2484 Ops.erase(Ops.begin());
2485 --Idx;
2486 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2487 // If we have a multiply of zero, it will always be zero.
2488 return Ops[0];
2489 } else if (Ops[0]->isAllOnesValue()) {
2490 // If we have a mul by -1 of an add, try distributing the -1 among the
2491 // add operands.
2492 if (Ops.size() == 2) {
2493 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2494 SmallVector<const SCEV *, 4> NewOps;
2495 bool AnyFolded = false;
2496 for (const SCEV *AddOp : Add->operands()) {
2497 const SCEV *Mul = getMulExpr(Ops[0], AddOp);
2498 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2499 NewOps.push_back(Mul);
2500 }
2501 if (AnyFolded)
2502 return getAddExpr(NewOps);
2503 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2504 // Negation preserves a recurrence's no self-wrap property.
2505 SmallVector<const SCEV *, 4> Operands;
2506 for (const SCEV *AddRecOp : AddRec->operands())
2507 Operands.push_back(getMulExpr(Ops[0], AddRecOp));
2508
2509 return getAddRecExpr(Operands, AddRec->getLoop(),
2510 AddRec->getNoWrapFlags(SCEV::FlagNW));
2511 }
2512 }
2513 }
2514
2515 if (Ops.size() == 1)
2516 return Ops[0];
2517 }
2518
2519 // Skip over the add expression until we get to a multiply.
2520 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2521 ++Idx;
2522
2523 // If there are mul operands inline them all into this expression.
2524 if (Idx < Ops.size()) {
2525 bool DeletedMul = false;
2526 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2527 // If we have an mul, expand the mul operands onto the end of the operands
2528 // list.
2529 Ops.erase(Ops.begin()+Idx);
2530 Ops.append(Mul->op_begin(), Mul->op_end());
2531 DeletedMul = true;
2532 }
2533
2534 // If we deleted at least one mul, we added operands to the end of the list,
2535 // and they are not necessarily sorted. Recurse to resort and resimplify
2536 // any operands we just acquired.
2537 if (DeletedMul)
2538 return getMulExpr(Ops);
2539 }
2540
2541 // If there are any add recurrences in the operands list, see if any other
2542 // added values are loop invariant. If so, we can fold them into the
2543 // recurrence.
2544 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2545 ++Idx;
2546
2547 // Scan over all recurrences, trying to fold loop invariants into them.
2548 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2549 // Scan all of the other operands to this mul and add them to the vector if
2550 // they are loop invariant w.r.t. the recurrence.
2551 SmallVector<const SCEV *, 8> LIOps;
2552 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2553 const Loop *AddRecLoop = AddRec->getLoop();
2554 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2555 if (isLoopInvariant(Ops[i], AddRecLoop)) {
2556 LIOps.push_back(Ops[i]);
2557 Ops.erase(Ops.begin()+i);
2558 --i; --e;
2559 }
2560
2561 // If we found some loop invariants, fold them into the recurrence.
2562 if (!LIOps.empty()) {
2563 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2564 SmallVector<const SCEV *, 4> NewOps;
2565 NewOps.reserve(AddRec->getNumOperands());
2566 const SCEV *Scale = getMulExpr(LIOps);
2567 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2568 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i)));
2569
2570 // Build the new addrec. Propagate the NUW and NSW flags if both the
2571 // outer mul and the inner addrec are guaranteed to have no overflow.
2572 //
2573 // No self-wrap cannot be guaranteed after changing the step size, but
2574 // will be inferred if either NUW or NSW is true.
2575 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
2576 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
2577
2578 // If all of the other operands were loop invariant, we are done.
2579 if (Ops.size() == 1) return NewRec;
2580
2581 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2582 for (unsigned i = 0;; ++i)
2583 if (Ops[i] == AddRec) {
2584 Ops[i] = NewRec;
2585 break;
2586 }
2587 return getMulExpr(Ops);
2588 }
2589
2590 // Okay, if there weren't any loop invariants to be folded, check to see if
2591 // there are multiple AddRec's with the same loop induction variable being
2592 // multiplied together. If so, we can fold them.
2593
2594 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2595 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2596 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2597 // ]]],+,...up to x=2n}.
2598 // Note that the arguments to choose() are always integers with values
2599 // known at compile time, never SCEV objects.
2600 //
2601 // The implementation avoids pointless extra computations when the two
2602 // addrec's are of different length (mathematically, it's equivalent to
2603 // an infinite stream of zeros on the right).
2604 bool OpsModified = false;
2605 for (unsigned OtherIdx = Idx+1;
2606 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2607 ++OtherIdx) {
2608 const SCEVAddRecExpr *OtherAddRec =
2609 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2610 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
2611 continue;
2612
2613 bool Overflow = false;
2614 Type *Ty = AddRec->getType();
2615 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
2616 SmallVector<const SCEV*, 7> AddRecOps;
2617 for (int x = 0, xe = AddRec->getNumOperands() +
2618 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
2619 const SCEV *Term = getZero(Ty);
2620 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
2621 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
2622 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
2623 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
2624 z < ze && !Overflow; ++z) {
2625 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
2626 uint64_t Coeff;
2627 if (LargerThan64Bits)
2628 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
2629 else
2630 Coeff = Coeff1*Coeff2;
2631 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
2632 const SCEV *Term1 = AddRec->getOperand(y-z);
2633 const SCEV *Term2 = OtherAddRec->getOperand(z);
2634 Term = getAddExpr(Term, getMulExpr(CoeffTerm, Term1,Term2));
2635 }
2636 }
2637 AddRecOps.push_back(Term);
2638 }
2639 if (!Overflow) {
2640 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(),
2641 SCEV::FlagAnyWrap);
2642 if (Ops.size() == 2) return NewAddRec;
2643 Ops[Idx] = NewAddRec;
2644 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2645 OpsModified = true;
2646 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
2647 if (!AddRec)
2648 break;
2649 }
2650 }
2651 if (OpsModified)
2652 return getMulExpr(Ops);
2653
2654 // Otherwise couldn't fold anything into this recurrence. Move onto the
2655 // next one.
2656 }
2657
2658 // Okay, it looks like we really DO need an mul expr. Check to see if we
2659 // already have one, otherwise create a new one.
2660 FoldingSetNodeID ID;
2661 ID.AddInteger(scMulExpr);
2662 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2663 ID.AddPointer(Ops[i]);
2664 void *IP = nullptr;
2665 SCEVMulExpr *S =
2666 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2667 if (!S) {
2668 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2669 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2670 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2671 O, Ops.size());
2672 UniqueSCEVs.InsertNode(S, IP);
2673 }
2674 S->setNoWrapFlags(Flags);
2675 return S;
2676}
2677
2678/// getUDivExpr - Get a canonical unsigned division expression, or something
2679/// simpler if possible.
2680const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
2681 const SCEV *RHS) {
2682 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2684, __PRETTY_FUNCTION__))
2683 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2684, __PRETTY_FUNCTION__))
2684 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2684, __PRETTY_FUNCTION__))
;
2685
2686 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
2687 if (RHSC->getValue()->equalsInt(1))
2688 return LHS; // X udiv 1 --> x
2689 // If the denominator is zero, the result of the udiv is undefined. Don't
2690 // try to analyze it, because the resolution chosen here may differ from
2691 // the resolution chosen in other parts of the compiler.
2692 if (!RHSC->getValue()->isZero()) {
2693 // Determine if the division can be folded into the operands of
2694 // its operands.
2695 // TODO: Generalize this to non-constants by using known-bits information.
2696 Type *Ty = LHS->getType();
2697 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
2698 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
2699 // For non-power-of-two values, effectively round the value up to the
2700 // nearest power of two.
2701 if (!RHSC->getAPInt().isPowerOf2())
2702 ++MaxShiftAmt;
2703 IntegerType *ExtTy =
2704 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
2705 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
2706 if (const SCEVConstant *Step =
2707 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
2708 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
2709 const APInt &StepInt = Step->getAPInt();
2710 const APInt &DivInt = RHSC->getAPInt();
2711 if (!StepInt.urem(DivInt) &&
2712 getZeroExtendExpr(AR, ExtTy) ==
2713 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2714 getZeroExtendExpr(Step, ExtTy),
2715 AR->getLoop(), SCEV::FlagAnyWrap)) {
2716 SmallVector<const SCEV *, 4> Operands;
2717 for (const SCEV *Op : AR->operands())
2718 Operands.push_back(getUDivExpr(Op, RHS));
2719 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
2720 }
2721 /// Get a canonical UDivExpr for a recurrence.
2722 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
2723 // We can currently only fold X%N if X is constant.
2724 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
2725 if (StartC && !DivInt.urem(StepInt) &&
2726 getZeroExtendExpr(AR, ExtTy) ==
2727 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
2728 getZeroExtendExpr(Step, ExtTy),
2729 AR->getLoop(), SCEV::FlagAnyWrap)) {
2730 const APInt &StartInt = StartC->getAPInt();
2731 const APInt &StartRem = StartInt.urem(StepInt);
2732 if (StartRem != 0)
2733 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
2734 AR->getLoop(), SCEV::FlagNW);
2735 }
2736 }
2737 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
2738 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
2739 SmallVector<const SCEV *, 4> Operands;
2740 for (const SCEV *Op : M->operands())
2741 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
2742 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
2743 // Find an operand that's safely divisible.
2744 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
2745 const SCEV *Op = M->getOperand(i);
2746 const SCEV *Div = getUDivExpr(Op, RHSC);
2747 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
2748 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
2749 M->op_end());
2750 Operands[i] = Div;
2751 return getMulExpr(Operands);
2752 }
2753 }
2754 }
2755 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
2756 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
2757 SmallVector<const SCEV *, 4> Operands;
2758 for (const SCEV *Op : A->operands())
2759 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
2760 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
2761 Operands.clear();
2762 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
2763 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
2764 if (isa<SCEVUDivExpr>(Op) ||
2765 getMulExpr(Op, RHS) != A->getOperand(i))
2766 break;
2767 Operands.push_back(Op);
2768 }
2769 if (Operands.size() == A->getNumOperands())
2770 return getAddExpr(Operands);
2771 }
2772 }
2773
2774 // Fold if both operands are constant.
2775 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
2776 Constant *LHSCV = LHSC->getValue();
2777 Constant *RHSCV = RHSC->getValue();
2778 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
2779 RHSCV)));
2780 }
2781 }
2782 }
2783
2784 FoldingSetNodeID ID;
2785 ID.AddInteger(scUDivExpr);
2786 ID.AddPointer(LHS);
2787 ID.AddPointer(RHS);
2788 void *IP = nullptr;
2789 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2790 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
2791 LHS, RHS);
2792 UniqueSCEVs.InsertNode(S, IP);
2793 return S;
2794}
2795
2796static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
2797 APInt A = C1->getAPInt().abs();
2798 APInt B = C2->getAPInt().abs();
2799 uint32_t ABW = A.getBitWidth();
2800 uint32_t BBW = B.getBitWidth();
2801
2802 if (ABW > BBW)
2803 B = B.zext(ABW);
2804 else if (ABW < BBW)
2805 A = A.zext(BBW);
2806
2807 return APIntOps::GreatestCommonDivisor(A, B);
2808}
2809
2810/// getUDivExactExpr - Get a canonical unsigned division expression, or
2811/// something simpler if possible. There is no representation for an exact udiv
2812/// in SCEV IR, but we can attempt to remove factors from the LHS and RHS.
2813/// We can't do this when it's not exact because the udiv may be clearing bits.
2814const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
2815 const SCEV *RHS) {
2816 // TODO: we could try to find factors in all sorts of things, but for now we
2817 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
2818 // end of this file for inspiration.
2819
2820 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
2821 if (!Mul)
2822 return getUDivExpr(LHS, RHS);
2823
2824 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
2825 // If the mulexpr multiplies by a constant, then that constant must be the
2826 // first element of the mulexpr.
2827 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
2828 if (LHSCst == RHSCst) {
2829 SmallVector<const SCEV *, 2> Operands;
2830 Operands.append(Mul->op_begin() + 1, Mul->op_end());
2831 return getMulExpr(Operands);
2832 }
2833
2834 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
2835 // that there's a factor provided by one of the other terms. We need to
2836 // check.
2837 APInt Factor = gcd(LHSCst, RHSCst);
2838 if (!Factor.isIntN(1)) {
2839 LHSCst =
2840 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
2841 RHSCst =
2842 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
2843 SmallVector<const SCEV *, 2> Operands;
2844 Operands.push_back(LHSCst);
2845 Operands.append(Mul->op_begin() + 1, Mul->op_end());
2846 LHS = getMulExpr(Operands);
2847 RHS = RHSCst;
2848 Mul = dyn_cast<SCEVMulExpr>(LHS);
2849 if (!Mul)
2850 return getUDivExactExpr(LHS, RHS);
2851 }
2852 }
2853 }
2854
2855 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
2856 if (Mul->getOperand(i) == RHS) {
2857 SmallVector<const SCEV *, 2> Operands;
2858 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
2859 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
2860 return getMulExpr(Operands);
2861 }
2862 }
2863
2864 return getUDivExpr(LHS, RHS);
2865}
2866
2867/// getAddRecExpr - Get an add recurrence expression for the specified loop.
2868/// Simplify the expression as much as possible.
2869const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
2870 const Loop *L,
2871 SCEV::NoWrapFlags Flags) {
2872 SmallVector<const SCEV *, 4> Operands;
2873 Operands.push_back(Start);
2874 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
2875 if (StepChrec->getLoop() == L) {
2876 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
2877 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
2878 }
2879
2880 Operands.push_back(Step);
2881 return getAddRecExpr(Operands, L, Flags);
2882}
2883
2884/// getAddRecExpr - Get an add recurrence expression for the specified loop.
2885/// Simplify the expression as much as possible.
2886const SCEV *
2887ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
2888 const Loop *L, SCEV::NoWrapFlags Flags) {
2889 if (Operands.size() == 1) return Operands[0];
2890#ifndef NDEBUG
2891 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
2892 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
2893 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2894, __PRETTY_FUNCTION__))
2894 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2894, __PRETTY_FUNCTION__))
;
2895 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
2896 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2897, __PRETTY_FUNCTION__))
2897 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 2897, __PRETTY_FUNCTION__))
;
2898#endif
2899
2900 if (Operands.back()->isZero()) {
2901 Operands.pop_back();
2902 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
2903 }
2904
2905 // It's tempting to want to call getMaxBackedgeTakenCount count here and
2906 // use that information to infer NUW and NSW flags. However, computing a
2907 // BE count requires calling getAddRecExpr, so we may not yet have a
2908 // meaningful BE count at this point (and if we don't, we'd be stuck
2909 // with a SCEVCouldNotCompute as the cached BE count).
2910
2911 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
2912
2913 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
2914 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
2915 const Loop *NestedLoop = NestedAR->getLoop();
2916 if (L->contains(NestedLoop)
2917 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
2918 : (!NestedLoop->contains(L) &&
2919 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
2920 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
2921 NestedAR->op_end());
2922 Operands[0] = NestedAR->getStart();
2923 // AddRecs require their operands be loop-invariant with respect to their
2924 // loops. Don't perform this transformation if it would break this
2925 // requirement.
2926 bool AllInvariant = all_of(
2927 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
2928
2929 if (AllInvariant) {
2930 // Create a recurrence for the outer loop with the same step size.
2931 //
2932 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
2933 // inner recurrence has the same property.
2934 SCEV::NoWrapFlags OuterFlags =
2935 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
2936
2937 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
2938 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
2939 return isLoopInvariant(Op, NestedLoop);
2940 });
2941
2942 if (AllInvariant) {
2943 // Ok, both add recurrences are valid after the transformation.
2944 //
2945 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
2946 // the outer recurrence has the same property.
2947 SCEV::NoWrapFlags InnerFlags =
2948 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
2949 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
2950 }
2951 }
2952 // Reset Operands to its original state.
2953 Operands[0] = NestedAR;
2954 }
2955 }
2956
2957 // Okay, it looks like we really DO need an addrec expr. Check to see if we
2958 // already have one, otherwise create a new one.
2959 FoldingSetNodeID ID;
2960 ID.AddInteger(scAddRecExpr);
2961 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
2962 ID.AddPointer(Operands[i]);
2963 ID.AddPointer(L);
2964 void *IP = nullptr;
2965 SCEVAddRecExpr *S =
2966 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2967 if (!S) {
2968 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
2969 std::uninitialized_copy(Operands.begin(), Operands.end(), O);
2970 S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator),
2971 O, Operands.size(), L);
2972 UniqueSCEVs.InsertNode(S, IP);
2973 }
2974 S->setNoWrapFlags(Flags);
2975 return S;
2976}
2977
2978const SCEV *
2979ScalarEvolution::getGEPExpr(Type *PointeeType, const SCEV *BaseExpr,
2980 const SmallVectorImpl<const SCEV *> &IndexExprs,
2981 bool InBounds) {
2982 // getSCEV(Base)->getType() has the same address space as Base->getType()
2983 // because SCEV::getType() preserves the address space.
2984 Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType());
2985 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
2986 // instruction to its SCEV, because the Instruction may be guarded by control
2987 // flow and the no-overflow bits may not be valid for the expression in any
2988 // context. This can be fixed similarly to how these flags are handled for
2989 // adds.
2990 SCEV::NoWrapFlags Wrap = InBounds ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
2991
2992 const SCEV *TotalOffset = getZero(IntPtrTy);
2993 // The address space is unimportant. The first thing we do on CurTy is getting
2994 // its element type.
2995 Type *CurTy = PointerType::getUnqual(PointeeType);
2996 for (const SCEV *IndexExpr : IndexExprs) {
2997 // Compute the (potentially symbolic) offset in bytes for this index.
2998 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
2999 // For a struct, add the member offset.
3000 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3001 unsigned FieldNo = Index->getZExtValue();
3002 const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo);
3003
3004 // Add the field offset to the running total offset.
3005 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3006
3007 // Update CurTy to the type of the field at Index.
3008 CurTy = STy->getTypeAtIndex(Index);
3009 } else {
3010 // Update CurTy to its element type.
3011 CurTy = cast<SequentialType>(CurTy)->getElementType();
3012 // For an array, add the element offset, explicitly scaled.
3013 const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy);
3014 // Getelementptr indices are signed.
3015 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy);
3016
3017 // Multiply the index by the element size to compute the element offset.
3018 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3019
3020 // Add the element offset to the running total offset.
3021 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3022 }
3023 }
3024
3025 // Add the total offset from all the GEP indices to the base.
3026 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3027}
3028
3029const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS,
3030 const SCEV *RHS) {
3031 SmallVector<const SCEV *, 2> Ops;
3032 Ops.push_back(LHS);
3033 Ops.push_back(RHS);
3034 return getSMaxExpr(Ops);
3035}
3036
3037const SCEV *
3038ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3039 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3039, __PRETTY_FUNCTION__))
;
3040 if (Ops.size() == 1) return Ops[0];
3041#ifndef NDEBUG
3042 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3043 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3044 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3045, __PRETTY_FUNCTION__))
3045 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3045, __PRETTY_FUNCTION__))
;
3046#endif
3047
3048 // Sort by complexity, this groups all similar expression types together.
3049 GroupByComplexity(Ops, &LI);
3050
3051 // If there are any constants, fold them together.
3052 unsigned Idx = 0;
3053 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3054 ++Idx;
3055 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3055, __PRETTY_FUNCTION__))
;
3056 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3057 // We found two constants, fold them together!
3058 ConstantInt *Fold = ConstantInt::get(
3059 getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt()));
3060 Ops[0] = getConstant(Fold);
3061 Ops.erase(Ops.begin()+1); // Erase the folded element
3062 if (Ops.size() == 1) return Ops[0];
3063 LHSC = cast<SCEVConstant>(Ops[0]);
3064 }
3065
3066 // If we are left with a constant minimum-int, strip it off.
3067 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
3068 Ops.erase(Ops.begin());
3069 --Idx;
3070 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
3071 // If we have an smax with a constant maximum-int, it will always be
3072 // maximum-int.
3073 return Ops[0];
3074 }
3075
3076 if (Ops.size() == 1) return Ops[0];
3077 }
3078
3079 // Find the first SMax
3080 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
3081 ++Idx;
3082
3083 // Check to see if one of the operands is an SMax. If so, expand its operands
3084 // onto our operand list, and recurse to simplify.
3085 if (Idx < Ops.size()) {
3086 bool DeletedSMax = false;
3087 while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
3088 Ops.erase(Ops.begin()+Idx);
3089 Ops.append(SMax->op_begin(), SMax->op_end());
3090 DeletedSMax = true;
3091 }
3092
3093 if (DeletedSMax)
3094 return getSMaxExpr(Ops);
3095 }
3096
3097 // Okay, check to see if the same value occurs in the operand list twice. If
3098 // so, delete one. Since we sorted the list, these values are required to
3099 // be adjacent.
3100 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3101 // X smax Y smax Y --> X smax Y
3102 // X smax Y --> X, if X is always greater than Y
3103 if (Ops[i] == Ops[i+1] ||
3104 isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
3105 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3106 --i; --e;
3107 } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
3108 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3109 --i; --e;
3110 }
3111
3112 if (Ops.size() == 1) return Ops[0];
3113
3114 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3114, __PRETTY_FUNCTION__))
;
3115
3116 // Okay, it looks like we really DO need an smax expr. Check to see if we
3117 // already have one, otherwise create a new one.
3118 FoldingSetNodeID ID;
3119 ID.AddInteger(scSMaxExpr);
3120 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3121 ID.AddPointer(Ops[i]);
3122 void *IP = nullptr;
3123 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3124 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3125 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3126 SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
3127 O, Ops.size());
3128 UniqueSCEVs.InsertNode(S, IP);
3129 return S;
3130}
3131
3132const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS,
3133 const SCEV *RHS) {
3134 SmallVector<const SCEV *, 2> Ops;
3135 Ops.push_back(LHS);
3136 Ops.push_back(RHS);
3137 return getUMaxExpr(Ops);
3138}
3139
3140const SCEV *
3141ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3142 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3142, __PRETTY_FUNCTION__))
;
3143 if (Ops.size() == 1) return Ops[0];
3144#ifndef NDEBUG
3145 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3146 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3147 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3148, __PRETTY_FUNCTION__))
3148 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3148, __PRETTY_FUNCTION__))
;
3149#endif
3150
3151 // Sort by complexity, this groups all similar expression types together.
3152 GroupByComplexity(Ops, &LI);
3153
3154 // If there are any constants, fold them together.
3155 unsigned Idx = 0;
3156 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3157 ++Idx;
3158 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3158, __PRETTY_FUNCTION__))
;
3159 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3160 // We found two constants, fold them together!
3161 ConstantInt *Fold = ConstantInt::get(
3162 getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt()));
3163 Ops[0] = getConstant(Fold);
3164 Ops.erase(Ops.begin()+1); // Erase the folded element
3165 if (Ops.size() == 1) return Ops[0];
3166 LHSC = cast<SCEVConstant>(Ops[0]);
3167 }
3168
3169 // If we are left with a constant minimum-int, strip it off.
3170 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
3171 Ops.erase(Ops.begin());
3172 --Idx;
3173 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
3174 // If we have an umax with a constant maximum-int, it will always be
3175 // maximum-int.
3176 return Ops[0];
3177 }
3178
3179 if (Ops.size() == 1) return Ops[0];
3180 }
3181
3182 // Find the first UMax
3183 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
3184 ++Idx;
3185
3186 // Check to see if one of the operands is a UMax. If so, expand its operands
3187 // onto our operand list, and recurse to simplify.
3188 if (Idx < Ops.size()) {
3189 bool DeletedUMax = false;
3190 while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
3191 Ops.erase(Ops.begin()+Idx);
3192 Ops.append(UMax->op_begin(), UMax->op_end());
3193 DeletedUMax = true;
3194 }
3195
3196 if (DeletedUMax)
3197 return getUMaxExpr(Ops);
3198 }
3199
3200 // Okay, check to see if the same value occurs in the operand list twice. If
3201 // so, delete one. Since we sorted the list, these values are required to
3202 // be adjacent.
3203 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3204 // X umax Y umax Y --> X umax Y
3205 // X umax Y --> X, if X is always greater than Y
3206 if (Ops[i] == Ops[i+1] ||
3207 isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
3208 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3209 --i; --e;
3210 } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
3211 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3212 --i; --e;
3213 }
3214
3215 if (Ops.size() == 1) return Ops[0];
3216
3217 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3217, __PRETTY_FUNCTION__))
;
3218
3219 // Okay, it looks like we really DO need a umax expr. Check to see if we
3220 // already have one, otherwise create a new one.
3221 FoldingSetNodeID ID;
3222 ID.AddInteger(scUMaxExpr);
3223 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3224 ID.AddPointer(Ops[i]);
3225 void *IP = nullptr;
3226 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3227 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3228 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3229 SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
3230 O, Ops.size());
3231 UniqueSCEVs.InsertNode(S, IP);
3232 return S;
3233}
3234
3235const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3236 const SCEV *RHS) {
3237 // ~smax(~x, ~y) == smin(x, y).
3238 return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3239}
3240
3241const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3242 const SCEV *RHS) {
3243 // ~umax(~x, ~y) == umin(x, y)
3244 return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3245}
3246
3247const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3248 // We can bypass creating a target-independent
3249 // constant expression and then folding it back into a ConstantInt.
3250 // This is just a compile-time optimization.
3251 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3252}
3253
3254const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3255 StructType *STy,
3256 unsigned FieldNo) {
3257 // We can bypass creating a target-independent
3258 // constant expression and then folding it back into a ConstantInt.
3259 // This is just a compile-time optimization.
3260 return getConstant(
3261 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3262}
3263
3264const SCEV *ScalarEvolution::getUnknown(Value *V) {
3265 // Don't attempt to do anything other than create a SCEVUnknown object
3266 // here. createSCEV only calls getUnknown after checking for all other
3267 // interesting possibilities, and any other code that calls getUnknown
3268 // is doing so in order to hide a value from SCEV canonicalization.
3269
3270 FoldingSetNodeID ID;
3271 ID.AddInteger(scUnknown);
3272 ID.AddPointer(V);
3273 void *IP = nullptr;
3274 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3275 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3276, __PRETTY_FUNCTION__))
3276 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3276, __PRETTY_FUNCTION__))
;
3277 return S;
3278 }
3279 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3280 FirstUnknown);
3281 FirstUnknown = cast<SCEVUnknown>(S);
3282 UniqueSCEVs.InsertNode(S, IP);
3283 return S;
3284}
3285
3286//===----------------------------------------------------------------------===//
3287// Basic SCEV Analysis and PHI Idiom Recognition Code
3288//
3289
3290/// isSCEVable - Test if values of the given type are analyzable within
3291/// the SCEV framework. This primarily includes integer types, and it
3292/// can optionally include pointer types if the ScalarEvolution class
3293/// has access to target-specific information.
3294bool ScalarEvolution::isSCEVable(Type *Ty) const {
3295 // Integers and pointers are always SCEVable.
3296 return Ty->isIntegerTy() || Ty->isPointerTy();
3297}
3298
3299/// getTypeSizeInBits - Return the size in bits of the specified type,
3300/// for which isSCEVable must return true.
3301uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3302 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3302, __PRETTY_FUNCTION__))
;
3303 return getDataLayout().getTypeSizeInBits(Ty);
3304}
3305
3306/// getEffectiveSCEVType - Return a type with the same bitwidth as
3307/// the given type and which represents how SCEV will treat the given
3308/// type, for which isSCEVable must return true. For pointer types,
3309/// this is the pointer-sized integer type.
3310Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3311 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3311, __PRETTY_FUNCTION__))
;
3312
3313 if (Ty->isIntegerTy())
3314 return Ty;
3315
3316 // The only other support type is pointer.
3317 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3317, __PRETTY_FUNCTION__))
;
3318 return getDataLayout().getIntPtrType(Ty);
3319}
3320
3321const SCEV *ScalarEvolution::getCouldNotCompute() {
3322 return CouldNotCompute.get();
3323}
3324
3325
3326bool ScalarEvolution::checkValidity(const SCEV *S) const {
3327 // Helper class working with SCEVTraversal to figure out if a SCEV contains
3328 // a SCEVUnknown with null value-pointer. FindInvalidSCEVUnknown::FindOne
3329 // is set iff if find such SCEVUnknown.
3330 //
3331 struct FindInvalidSCEVUnknown {
3332 bool FindOne;
3333 FindInvalidSCEVUnknown() { FindOne = false; }
3334 bool follow(const SCEV *S) {
3335 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
3336 case scConstant:
3337 return false;
3338 case scUnknown:
3339 if (!cast<SCEVUnknown>(S)->getValue())
3340 FindOne = true;
3341 return false;
3342 default:
3343 return true;
3344 }
3345 }
3346 bool isDone() const { return FindOne; }
3347 };
3348
3349 FindInvalidSCEVUnknown F;
3350 SCEVTraversal<FindInvalidSCEVUnknown> ST(F);
3351 ST.visitAll(S);
3352
3353 return !F.FindOne;
3354}
3355
3356namespace {
3357// Helper class working with SCEVTraversal to figure out if a SCEV contains
3358// a sub SCEV of scAddRecExpr type. FindInvalidSCEVUnknown::FoundOne is set
3359// iff if such sub scAddRecExpr type SCEV is found.
3360struct FindAddRecurrence {
3361 bool FoundOne;
3362 FindAddRecurrence() : FoundOne(false) {}
3363
3364 bool follow(const SCEV *S) {
3365 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
3366 case scAddRecExpr:
3367 FoundOne = true;
3368 case scConstant:
3369 case scUnknown:
3370 case scCouldNotCompute:
3371 return false;
3372 default:
3373 return true;
3374 }
3375 }
3376 bool isDone() const { return FoundOne; }
3377};
3378}
3379
3380bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3381 HasRecMapType::iterator I = HasRecMap.find_as(S);
3382 if (I != HasRecMap.end())
3383 return I->second;
3384
3385 FindAddRecurrence F;
3386 SCEVTraversal<FindAddRecurrence> ST(F);
3387 ST.visitAll(S);
3388 HasRecMap.insert({S, F.FoundOne});
3389 return F.FoundOne;
3390}
3391
3392/// getSCEVValues - Return the Value set from S.
3393SetVector<Value *> *ScalarEvolution::getSCEVValues(const SCEV *S) {
3394 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3395 if (SI == ExprValueMap.end())
3396 return nullptr;
3397#ifndef NDEBUG
3398 if (VerifySCEVMap) {
3399 // Check there is no dangling Value in the set returned.
3400 for (const auto &VE : SI->second)
3401 assert(ValueExprMap.count(VE))((ValueExprMap.count(VE)) ? static_cast<void> (0) : __assert_fail
("ValueExprMap.count(VE)", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3401, __PRETTY_FUNCTION__))
;
3402 }
3403#endif
3404 return &SI->second;
3405}
3406
3407/// eraseValueFromMap - Erase Value from ValueExprMap and ExprValueMap.
3408/// If ValueExprMap.erase(V) is not used together with forgetMemoizedResults(S),
3409/// eraseValueFromMap should be used instead to ensure whenever V->S is removed
3410/// from ValueExprMap, V is also removed from the set of ExprValueMap[S].
3411void ScalarEvolution::eraseValueFromMap(Value *V) {
3412 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3413 if (I != ValueExprMap.end()) {
3414 const SCEV *S = I->second;
3415 SetVector<Value *> *SV = getSCEVValues(S);
3416 // Remove V from the set of ExprValueMap[S]
3417 if (SV)
3418 SV->remove(V);
3419 ValueExprMap.erase(V);
3420 }
3421}
3422
3423/// getSCEV - Return an existing SCEV if it exists, otherwise analyze the
3424/// expression and create a new one.
3425const SCEV *ScalarEvolution::getSCEV(Value *V) {
3426 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3426, __PRETTY_FUNCTION__))
;
3427
3428 const SCEV *S = getExistingSCEV(V);
3429 if (S == nullptr) {
3430 S = createSCEV(V);
3431 // During PHI resolution, it is possible to create two SCEVs for the same
3432 // V, so it is needed to double check whether V->S is inserted into
3433 // ValueExprMap before insert S->V into ExprValueMap.
3434 std::pair<ValueExprMapType::iterator, bool> Pair =
3435 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3436 if (Pair.second)
3437 ExprValueMap[S].insert(V);
3438 }
3439 return S;
3440}
3441
3442const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3443 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3443, __PRETTY_FUNCTION__))
;
3444
3445 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3446 if (I != ValueExprMap.end()) {
3447 const SCEV *S = I->second;
3448 if (checkValidity(S))
3449 return S;
3450 forgetMemoizedResults(S);
3451 ValueExprMap.erase(I);
3452 }
3453 return nullptr;
3454}
3455
3456/// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
3457///
3458const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3459 SCEV::NoWrapFlags Flags) {
3460 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3461 return getConstant(
3462 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3463
3464 Type *Ty = V->getType();
3465 Ty = getEffectiveSCEVType(Ty);
3466 return getMulExpr(
3467 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3468}
3469
3470/// getNotSCEV - Return a SCEV corresponding to ~V = -1-V
3471const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3472 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3473 return getConstant(
3474 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3475
3476 Type *Ty = V->getType();
3477 Ty = getEffectiveSCEVType(Ty);
3478 const SCEV *AllOnes =
3479 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3480 return getMinusSCEV(AllOnes, V);
3481}
3482
3483/// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1.
3484const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3485 SCEV::NoWrapFlags Flags) {
3486 // Fast path: X - X --> 0.
3487 if (LHS == RHS)
3488 return getZero(LHS->getType());
3489
3490 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3491 // makes it so that we cannot make much use of NUW.
3492 auto AddFlags = SCEV::FlagAnyWrap;
3493 const bool RHSIsNotMinSigned =
3494 !getSignedRange(RHS).getSignedMin().isMinSignedValue();
3495 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3496 // Let M be the minimum representable signed value. Then (-1)*RHS
3497 // signed-wraps if and only if RHS is M. That can happen even for
3498 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3499 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3500 // (-1)*RHS, we need to prove that RHS != M.
3501 //
3502 // If LHS is non-negative and we know that LHS - RHS does not
3503 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3504 // either by proving that RHS > M or that LHS >= 0.
3505 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
3506 AddFlags = SCEV::FlagNSW;
3507 }
3508 }
3509
3510 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
3511 // RHS is NSW and LHS >= 0.
3512 //
3513 // The difficulty here is that the NSW flag may have been proven
3514 // relative to a loop that is to be found in a recurrence in LHS and
3515 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
3516 // larger scope than intended.
3517 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3518
3519 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags);
3520}
3521
3522/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion of the
3523/// input value to the specified type. If the type must be extended, it is zero
3524/// extended.
3525const SCEV *
3526ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) {
3527 Type *SrcTy = V->getType();
3528 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3530, __PRETTY_FUNCTION__))
3529 (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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3530, __PRETTY_FUNCTION__))
3530 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3530, __PRETTY_FUNCTION__))
;
3531 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3532 return V; // No conversion
3533 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3534 return getTruncateExpr(V, Ty);
3535 return getZeroExtendExpr(V, Ty);
3536}
3537
3538/// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion of the
3539/// input value to the specified type. If the type must be extended, it is sign
3540/// extended.
3541const SCEV *
3542ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
3543 Type *Ty) {
3544 Type *SrcTy = V->getType();
3545 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3547, __PRETTY_FUNCTION__))
3546 (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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3547, __PRETTY_FUNCTION__))
3547 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3547, __PRETTY_FUNCTION__))
;
3548 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3549 return V; // No conversion
3550 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3551 return getTruncateExpr(V, Ty);
3552 return getSignExtendExpr(V, Ty);
3553}
3554
3555/// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of the
3556/// input value to the specified type. If the type must be extended, it is zero
3557/// extended. The conversion must not be narrowing.
3558const SCEV *
3559ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
3560 Type *SrcTy = V->getType();
3561 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3563, __PRETTY_FUNCTION__))
3562 (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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3563, __PRETTY_FUNCTION__))
3563 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3563, __PRETTY_FUNCTION__))
;
3564 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3565, __PRETTY_FUNCTION__))
3565 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3565, __PRETTY_FUNCTION__))
;
3566 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3567 return V; // No conversion
3568 return getZeroExtendExpr(V, Ty);
3569}
3570
3571/// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of the
3572/// input value to the specified type. If the type must be extended, it is sign
3573/// extended. The conversion must not be narrowing.
3574const SCEV *
3575ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
3576 Type *SrcTy = V->getType();
3577 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3579, __PRETTY_FUNCTION__))
3578 (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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3579, __PRETTY_FUNCTION__))
3579 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3579, __PRETTY_FUNCTION__))
;
3580 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3581, __PRETTY_FUNCTION__))
3581 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3581, __PRETTY_FUNCTION__))
;
3582 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3583 return V; // No conversion
3584 return getSignExtendExpr(V, Ty);
3585}
3586
3587/// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
3588/// the input value to the specified type. If the type must be extended,
3589/// it is extended with unspecified bits. The conversion must not be
3590/// narrowing.
3591const SCEV *
3592ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
3593 Type *SrcTy = V->getType();
3594 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3596, __PRETTY_FUNCTION__))
3595 (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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3596, __PRETTY_FUNCTION__))
3596 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3596, __PRETTY_FUNCTION__))
;
3597 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3598, __PRETTY_FUNCTION__))
3598 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3598, __PRETTY_FUNCTION__))
;
3599 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3600 return V; // No conversion
3601 return getAnyExtendExpr(V, Ty);
3602}
3603
3604/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
3605/// input value to the specified type. The conversion must not be widening.
3606const SCEV *
3607ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
3608 Type *SrcTy = V->getType();
3609 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3611, __PRETTY_FUNCTION__))
3610 (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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3611, __PRETTY_FUNCTION__))
3611 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3611, __PRETTY_FUNCTION__))
;
3612 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3613, __PRETTY_FUNCTION__))
3613 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3613, __PRETTY_FUNCTION__))
;
3614 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3615 return V; // No conversion
3616 return getTruncateExpr(V, Ty);
3617}
3618
3619/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
3620/// the types using zero-extension, and then perform a umax operation
3621/// with them.
3622const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
3623 const SCEV *RHS) {
3624 const SCEV *PromotedLHS = LHS;
3625 const SCEV *PromotedRHS = RHS;
3626
3627 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3628 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3629 else
3630 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3631
3632 return getUMaxExpr(PromotedLHS, PromotedRHS);
3633}
3634
3635/// getUMinFromMismatchedTypes - Promote the operands to the wider of
3636/// the types using zero-extension, and then perform a umin operation
3637/// with them.
3638const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3639 const SCEV *RHS) {
3640 const SCEV *PromotedLHS = LHS;
3641 const SCEV *PromotedRHS = RHS;
3642
3643 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3644 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3645 else
3646 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3647
3648 return getUMinExpr(PromotedLHS, PromotedRHS);
3649}
3650
3651/// getPointerBase - Transitively follow the chain of pointer-type operands
3652/// until reaching a SCEV that does not have a single pointer operand. This
3653/// returns a SCEVUnknown pointer for well-formed pointer-type expressions,
3654/// but corner cases do exist.
3655const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
3656 // A pointer operand may evaluate to a nonpointer expression, such as null.
3657 if (!V->getType()->isPointerTy())
3658 return V;
3659
3660 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
3661 return getPointerBase(Cast->getOperand());
3662 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
3663 const SCEV *PtrOp = nullptr;
3664 for (const SCEV *NAryOp : NAry->operands()) {
3665 if (NAryOp->getType()->isPointerTy()) {
3666 // Cannot find the base of an expression with multiple pointer operands.
3667 if (PtrOp)
3668 return V;
3669 PtrOp = NAryOp;
3670 }
3671 }
3672 if (!PtrOp)
3673 return V;
3674 return getPointerBase(PtrOp);
3675 }
3676 return V;
3677}
3678
3679/// PushDefUseChildren - Push users of the given Instruction
3680/// onto the given Worklist.
3681static void
3682PushDefUseChildren(Instruction *I,
3683 SmallVectorImpl<Instruction *> &Worklist) {
3684 // Push the def-use children onto the Worklist stack.
3685 for (User *U : I->users())
3686 Worklist.push_back(cast<Instruction>(U));
3687}
3688
3689/// ForgetSymbolicValue - This looks up computed SCEV values for all
3690/// instructions that depend on the given instruction and removes them from
3691/// the ValueExprMapType map if they reference SymName. This is used during PHI
3692/// resolution.
3693void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
3694 SmallVector<Instruction *, 16> Worklist;
3695 PushDefUseChildren(PN, Worklist);
3696
3697 SmallPtrSet<Instruction *, 8> Visited;
3698 Visited.insert(PN);
3699 while (!Worklist.empty()) {
3700 Instruction *I = Worklist.pop_back_val();
3701 if (!Visited.insert(I).second)
3702 continue;
3703
3704 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
3705 if (It != ValueExprMap.end()) {
3706 const SCEV *Old = It->second;
3707
3708 // Short-circuit the def-use traversal if the symbolic name
3709 // ceases to appear in expressions.
3710 if (Old != SymName && !hasOperand(Old, SymName))
3711 continue;
3712
3713 // SCEVUnknown for a PHI either means that it has an unrecognized
3714 // structure, it's a PHI that's in the progress of being computed
3715 // by createNodeForPHI, or it's a single-value PHI. In the first case,
3716 // additional loop trip count information isn't going to change anything.
3717 // In the second case, createNodeForPHI will perform the necessary
3718 // updates on its own when it gets to that point. In the third, we do
3719 // want to forget the SCEVUnknown.
3720 if (!isa<PHINode>(I) ||
3721 !isa<SCEVUnknown>(Old) ||
3722 (I != PN && Old == SymName)) {
3723 forgetMemoizedResults(Old);
3724 ValueExprMap.erase(It);
3725 }
3726 }
3727
3728 PushDefUseChildren(I, Worklist);
3729 }
3730}
3731
3732namespace {
3733class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
3734public:
3735 static const SCEV *rewrite(const SCEV *S, const Loop *L,
3736 ScalarEvolution &SE) {
3737 SCEVInitRewriter Rewriter(L, SE);
3738 const SCEV *Result = Rewriter.visit(S);
3739 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
3740 }
3741
3742 SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
3743 : SCEVRewriteVisitor(SE), L(L), Valid(true) {}
3744
3745 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
3746 if (!(SE.getLoopDisposition(Expr, L) == ScalarEvolution::LoopInvariant))
3747 Valid = false;
3748 return Expr;
3749 }
3750
3751 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
3752 // Only allow AddRecExprs for this loop.
3753 if (Expr->getLoop() == L)
3754 return Expr->getStart();
3755 Valid = false;
3756 return Expr;
3757 }
3758
3759 bool isValid() { return Valid; }
3760
3761private:
3762 const Loop *L;
3763 bool Valid;
3764};
3765
3766class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
3767public:
3768 static const SCEV *rewrite(const SCEV *S, const Loop *L,
3769 ScalarEvolution &SE) {
3770 SCEVShiftRewriter Rewriter(L, SE);
3771 const SCEV *Result = Rewriter.visit(S);
3772 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
3773 }
3774
3775 SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
3776 : SCEVRewriteVisitor(SE), L(L), Valid(true) {}
3777
3778 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
3779 // Only allow AddRecExprs for this loop.
3780 if (!(SE.getLoopDisposition(Expr, L) == ScalarEvolution::LoopInvariant))
3781 Valid = false;
3782 return Expr;
3783 }
3784
3785 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
3786 if (Expr->getLoop() == L && Expr->isAffine())
3787 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
3788 Valid = false;
3789 return Expr;
3790 }
3791 bool isValid() { return Valid; }
3792
3793private:
3794 const Loop *L;
3795 bool Valid;
3796};
3797} // end anonymous namespace
3798
3799SCEV::NoWrapFlags
3800ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
3801 if (!AR->isAffine())
3802 return SCEV::FlagAnyWrap;
3803
3804 typedef OverflowingBinaryOperator OBO;
3805 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
3806
3807 if (!AR->hasNoSignedWrap()) {
3808 ConstantRange AddRecRange = getSignedRange(AR);
3809 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
3810
3811 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
3812 Instruction::Add, IncRange, OBO::NoSignedWrap);
3813 if (NSWRegion.contains(AddRecRange))
3814 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
3815 }
3816
3817 if (!AR->hasNoUnsignedWrap()) {
3818 ConstantRange AddRecRange = getUnsignedRange(AR);
3819 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
3820
3821 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
3822 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
3823 if (NUWRegion.contains(AddRecRange))
3824 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
3825 }
3826
3827 return Result;
3828}
3829
3830namespace {
3831/// Represents an abstract binary operation. This may exist as a
3832/// normal instruction or constant expression, or may have been
3833/// derived from an expression tree.
3834struct BinaryOp {
3835 unsigned Opcode;
3836 Value *LHS;
3837 Value *RHS;
3838 bool IsNSW;
3839 bool IsNUW;
3840
3841 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
3842 /// constant expression.
3843 Operator *Op;
3844
3845 explicit BinaryOp(Operator *Op)
3846 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
3847 IsNSW(false), IsNUW(false), Op(Op) {
3848 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
3849 IsNSW = OBO->hasNoSignedWrap();
3850 IsNUW = OBO->hasNoUnsignedWrap();
3851 }
3852 }
3853
3854 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
3855 bool IsNUW = false)
3856 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW),
3857 Op(nullptr) {}
3858};
3859}
3860
3861
3862/// Try to map \p V into a BinaryOp, and return \c None on failure.
3863static Optional<BinaryOp> MatchBinaryOp(Value *V) {
3864 auto *Op = dyn_cast<Operator>(V);
3865 if (!Op)
3866 return None;
3867
3868 // Implementation detail: all the cleverness here should happen without
3869 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
3870 // SCEV expressions when possible, and we should not break that.
3871
3872 switch (Op->getOpcode()) {
3873 case Instruction::Add:
3874 case Instruction::Sub:
3875 case Instruction::Mul:
3876 case Instruction::UDiv:
3877 case Instruction::And:
3878 case Instruction::Or:
3879 case Instruction::AShr:
3880 case Instruction::Shl:
3881 return BinaryOp(Op);
3882
3883 case Instruction::Xor:
3884 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
3885 // If the RHS of the xor is a signbit, then this is just an add.
3886 // Instcombine turns add of signbit into xor as a strength reduction step.
3887 if (RHSC->getValue().isSignBit())
3888 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
3889 return BinaryOp(Op);
3890
3891 case Instruction::LShr:
3892 // Turn logical shift right of a constant into a unsigned divide.
3893 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
3894 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
3895
3896 // If the shift count is not less than the bitwidth, the result of
3897 // the shift is undefined. Don't try to analyze it, because the
3898 // resolution chosen here may differ from the resolution chosen in
3899 // other parts of the compiler.
3900 if (SA->getValue().ult(BitWidth)) {
3901 Constant *X =
3902 ConstantInt::get(SA->getContext(),
3903 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
3904 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
3905 }
3906 }
3907 return BinaryOp(Op);
3908
3909 default:
3910 break;
3911 }
3912
3913 return None;
3914}
3915
3916const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
3917 const Loop *L = LI.getLoopFor(PN->getParent());
3918 if (!L || L->getHeader() != PN->getParent())
3919 return nullptr;
3920
3921 // The loop may have multiple entrances or multiple exits; we can analyze
3922 // this phi as an addrec if it has a unique entry value and a unique
3923 // backedge value.
3924 Value *BEValueV = nullptr, *StartValueV = nullptr;
3925 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
3926 Value *V = PN->getIncomingValue(i);
3927 if (L->contains(PN->getIncomingBlock(i))) {
3928 if (!BEValueV) {
3929 BEValueV = V;
3930 } else if (BEValueV != V) {
3931 BEValueV = nullptr;
3932 break;
3933 }
3934 } else if (!StartValueV) {
3935 StartValueV = V;
3936 } else if (StartValueV != V) {
3937 StartValueV = nullptr;
3938 break;
3939 }
3940 }
3941 if (BEValueV && StartValueV) {
3942 // While we are analyzing this PHI node, handle its value symbolically.
3943 const SCEV *SymbolicName = getUnknown(PN);
3944 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3945, __PRETTY_FUNCTION__))
3945 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 3945, __PRETTY_FUNCTION__))
;
3946 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
3947
3948 // Using this symbolic name for the PHI, analyze the value coming around
3949 // the back-edge.
3950 const SCEV *BEValue = getSCEV(BEValueV);
3951
3952 // NOTE: If BEValue is loop invariant, we know that the PHI node just
3953 // has a special value for the first iteration of the loop.
3954
3955 // If the value coming around the backedge is an add with the symbolic
3956 // value we just inserted, then we found a simple induction variable!
3957 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
3958 // If there is a single occurrence of the symbolic value, replace it
3959 // with a recurrence.
3960 unsigned FoundIndex = Add->getNumOperands();
3961 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
3962 if (Add->getOperand(i) == SymbolicName)
3963 if (FoundIndex == e) {
3964 FoundIndex = i;
3965 break;
3966 }
3967
3968 if (FoundIndex != Add->getNumOperands()) {
3969 // Create an add with everything but the specified operand.
3970 SmallVector<const SCEV *, 8> Ops;
3971 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
3972 if (i != FoundIndex)
3973 Ops.push_back(Add->getOperand(i));
3974 const SCEV *Accum = getAddExpr(Ops);
3975
3976 // This is not a valid addrec if the step amount is varying each
3977 // loop iteration, but is not itself an addrec in this loop.
3978 if (isLoopInvariant(Accum, L) ||
3979 (isa<SCEVAddRecExpr>(Accum) &&
3980 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
3981 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
3982
3983 // If the increment doesn't overflow, then neither the addrec nor
3984 // the post-increment will overflow.
3985 if (auto BO = MatchBinaryOp(BEValueV)) {
3986 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
3987 if (BO->IsNUW)
3988 Flags = setFlags(Flags, SCEV::FlagNUW);
3989 if (BO->IsNSW)
3990 Flags = setFlags(Flags, SCEV::FlagNSW);
3991 }
3992 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
3993 // If the increment is an inbounds GEP, then we know the address
3994 // space cannot be wrapped around. We cannot make any guarantee
3995 // about signed or unsigned overflow because pointers are
3996 // unsigned but we may have a negative index from the base
3997 // pointer. We can guarantee that no unsigned wrap occurs if the
3998 // indices form a positive value.
3999 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
4000 Flags = setFlags(Flags, SCEV::FlagNW);
4001
4002 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
4003 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
4004 Flags = setFlags(Flags, SCEV::FlagNUW);
4005 }
4006
4007 // We cannot transfer nuw and nsw flags from subtraction
4008 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
4009 // for instance.
4010 }
4011
4012 const SCEV *StartVal = getSCEV(StartValueV);
4013 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4014
4015 // Since the no-wrap flags are on the increment, they apply to the
4016 // post-incremented value as well.
4017 if (isLoopInvariant(Accum, L))
4018 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4019
4020 // Okay, for the entire analysis of this edge we assumed the PHI
4021 // to be symbolic. We now need to go back and purge all of the
4022 // entries for the scalars that use the symbolic expression.
4023 forgetSymbolicName(PN, SymbolicName);
4024 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4025 return PHISCEV;
4026 }
4027 }
4028 } else {
4029 // Otherwise, this could be a loop like this:
4030 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
4031 // In this case, j = {1,+,1} and BEValue is j.
4032 // Because the other in-value of i (0) fits the evolution of BEValue
4033 // i really is an addrec evolution.
4034 //
4035 // We can generalize this saying that i is the shifted value of BEValue
4036 // by one iteration:
4037 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
4038 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
4039 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this);
4040 if (Shifted != getCouldNotCompute() &&
4041 Start != getCouldNotCompute()) {
4042 const SCEV *StartVal = getSCEV(StartValueV);
4043 if (Start == StartVal) {
4044 // Okay, for the entire analysis of this edge we assumed the PHI
4045 // to be symbolic. We now need to go back and purge all of the
4046 // entries for the scalars that use the symbolic expression.
4047 forgetSymbolicName(PN, SymbolicName);
4048 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
4049 return Shifted;
4050 }
4051 }
4052 }
4053
4054 // Remove the temporary PHI node SCEV that has been inserted while intending
4055 // to create an AddRecExpr for this PHI node. We can not keep this temporary
4056 // as it will prevent later (possibly simpler) SCEV expressions to be added
4057 // to the ValueExprMap.
4058 ValueExprMap.erase(PN);
4059 }
4060
4061 return nullptr;
4062}
4063
4064// Checks if the SCEV S is available at BB. S is considered available at BB
4065// if S can be materialized at BB without introducing a fault.
4066static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
4067 BasicBlock *BB) {
4068 struct CheckAvailable {
4069 bool TraversalDone = false;
4070 bool Available = true;
4071
4072 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
4073 BasicBlock *BB = nullptr;
4074 DominatorTree &DT;
4075
4076 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
4077 : L(L), BB(BB), DT(DT) {}
4078
4079 bool setUnavailable() {
4080 TraversalDone = true;
4081 Available = false;
4082 return false;
4083 }
4084
4085 bool follow(const SCEV *S) {
4086 switch (S->getSCEVType()) {
4087 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
4088 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
4089 // These expressions are available if their operand(s) is/are.
4090 return true;
4091
4092 case scAddRecExpr: {
4093 // We allow add recurrences that are on the loop BB is in, or some
4094 // outer loop. This guarantees availability because the value of the
4095 // add recurrence at BB is simply the "current" value of the induction
4096 // variable. We can relax this in the future; for instance an add
4097 // recurrence on a sibling dominating loop is also available at BB.
4098 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
4099 if (L && (ARLoop == L || ARLoop->contains(L)))
4100 return true;
4101
4102 return setUnavailable();
4103 }
4104
4105 case scUnknown: {
4106 // For SCEVUnknown, we check for simple dominance.
4107 const auto *SU = cast<SCEVUnknown>(S);
4108 Value *V = SU->getValue();
4109
4110 if (isa<Argument>(V))
4111 return false;
4112
4113 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
4114 return false;
4115
4116 return setUnavailable();
4117 }
4118
4119 case scUDivExpr:
4120 case scCouldNotCompute:
4121 // We do not try to smart about these at all.
4122 return setUnavailable();
4123 }
4124 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4124)
;
4125 }
4126
4127 bool isDone() { return TraversalDone; }
4128 };
4129
4130 CheckAvailable CA(L, BB, DT);
4131 SCEVTraversal<CheckAvailable> ST(CA);
4132
4133 ST.visitAll(S);
4134 return CA.Available;
4135}
4136
4137// Try to match a control flow sequence that branches out at BI and merges back
4138// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
4139// match.
4140static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
4141 Value *&C, Value *&LHS, Value *&RHS) {
4142 C = BI->getCondition();
4143
4144 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
4145 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
4146
4147 if (!LeftEdge.isSingleEdge())
4148 return false;
4149
4150 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4150, __PRETTY_FUNCTION__))
;
4151
4152 Use &LeftUse = Merge->getOperandUse(0);
4153 Use &RightUse = Merge->getOperandUse(1);
4154
4155 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
4156 LHS = LeftUse;
4157 RHS = RightUse;
4158 return true;
4159 }
4160
4161 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
4162 LHS = RightUse;
4163 RHS = LeftUse;
4164 return true;
4165 }
4166
4167 return false;
4168}
4169
4170const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
4171 if (PN->getNumIncomingValues() == 2) {
4172 const Loop *L = LI.getLoopFor(PN->getParent());
4173
4174 // We don't want to break LCSSA, even in a SCEV expression tree.
4175 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
4176 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
4177 return nullptr;
4178
4179 // Try to match
4180 //
4181 // br %cond, label %left, label %right
4182 // left:
4183 // br label %merge
4184 // right:
4185 // br label %merge
4186 // merge:
4187 // V = phi [ %x, %left ], [ %y, %right ]
4188 //
4189 // as "select %cond, %x, %y"
4190
4191 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
4192 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4192, __PRETTY_FUNCTION__))
;
4193
4194 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
4195 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
4196
4197 if (BI && BI->isConditional() &&
4198 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
4199 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
4200 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
4201 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
4202 }
4203
4204 return nullptr;
4205}
4206
4207const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
4208 if (const SCEV *S = createAddRecFromPHI(PN))
4209 return S;
4210
4211 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
4212 return S;
4213
4214 // If the PHI has a single incoming value, follow that value, unless the
4215 // PHI's incoming blocks are in a different loop, in which case doing so
4216 // risks breaking LCSSA form. Instcombine would normally zap these, but
4217 // it doesn't have DominatorTree information, so it may miss cases.
4218 if (Value *V = SimplifyInstruction(PN, getDataLayout(), &TLI, &DT, &AC))
4219 if (LI.replacementPreservesLCSSAForm(PN, V))
4220 return getSCEV(V);
4221
4222 // If it's not a loop phi, we can't handle it yet.
4223 return getUnknown(PN);
4224}
4225
4226const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
4227 Value *Cond,
4228 Value *TrueVal,
4229 Value *FalseVal) {
4230 // Handle "constant" branch or select. This can occur for instance when a
4231 // loop pass transforms an inner loop and moves on to process the outer loop.
4232 if (auto *CI = dyn_cast<ConstantInt>(Cond))
4233 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
4234
4235 // Try to match some simple smax or umax patterns.
4236 auto *ICI = dyn_cast<ICmpInst>(Cond);
4237 if (!ICI)
4238 return getUnknown(I);
4239
4240 Value *LHS = ICI->getOperand(0);
4241 Value *RHS = ICI->getOperand(1);
4242
4243 switch (ICI->getPredicate()) {
4244 case ICmpInst::ICMP_SLT:
4245 case ICmpInst::ICMP_SLE:
4246 std::swap(LHS, RHS);
4247 // fall through
4248 case ICmpInst::ICMP_SGT:
4249 case ICmpInst::ICMP_SGE:
4250 // a >s b ? a+x : b+x -> smax(a, b)+x
4251 // a >s b ? b+x : a+x -> smin(a, b)+x
4252 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
4253 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
4254 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
4255 const SCEV *LA = getSCEV(TrueVal);
4256 const SCEV *RA = getSCEV(FalseVal);
4257 const SCEV *LDiff = getMinusSCEV(LA, LS);
4258 const SCEV *RDiff = getMinusSCEV(RA, RS);
4259 if (LDiff == RDiff)
4260 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
4261 LDiff = getMinusSCEV(LA, RS);
4262 RDiff = getMinusSCEV(RA, LS);
4263 if (LDiff == RDiff)
4264 return getAddExpr(getSMinExpr(LS, RS), LDiff);
4265 }
4266 break;
4267 case ICmpInst::ICMP_ULT:
4268 case ICmpInst::ICMP_ULE:
4269 std::swap(LHS, RHS);
4270 // fall through
4271 case ICmpInst::ICMP_UGT:
4272 case ICmpInst::ICMP_UGE:
4273 // a >u b ? a+x : b+x -> umax(a, b)+x
4274 // a >u b ? b+x : a+x -> umin(a, b)+x
4275 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
4276 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4277 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
4278 const SCEV *LA = getSCEV(TrueVal);
4279 const SCEV *RA = getSCEV(FalseVal);
4280 const SCEV *LDiff = getMinusSCEV(LA, LS);
4281 const SCEV *RDiff = getMinusSCEV(RA, RS);
4282 if (LDiff == RDiff)
4283 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
4284 LDiff = getMinusSCEV(LA, RS);
4285 RDiff = getMinusSCEV(RA, LS);
4286 if (LDiff == RDiff)
4287 return getAddExpr(getUMinExpr(LS, RS), LDiff);
4288 }
4289 break;
4290 case ICmpInst::ICMP_NE:
4291 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
4292 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
4293 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
4294 const SCEV *One = getOne(I->getType());
4295 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4296 const SCEV *LA = getSCEV(TrueVal);
4297 const SCEV *RA = getSCEV(FalseVal);
4298 const SCEV *LDiff = getMinusSCEV(LA, LS);
4299 const SCEV *RDiff = getMinusSCEV(RA, One);
4300 if (LDiff == RDiff)
4301 return getAddExpr(getUMaxExpr(One, LS), LDiff);
4302 }
4303 break;
4304 case ICmpInst::ICMP_EQ:
4305 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
4306 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
4307 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
4308 const SCEV *One = getOne(I->getType());
4309 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
4310 const SCEV *LA = getSCEV(TrueVal);
4311 const SCEV *RA = getSCEV(FalseVal);
4312 const SCEV *LDiff = getMinusSCEV(LA, One);
4313 const SCEV *RDiff = getMinusSCEV(RA, LS);
4314 if (LDiff == RDiff)
4315 return getAddExpr(getUMaxExpr(One, LS), LDiff);
4316 }
4317 break;
4318 default:
4319 break;
4320 }
4321
4322 return getUnknown(I);
4323}
4324
4325/// createNodeForGEP - Expand GEP instructions into add and multiply
4326/// operations. This allows them to be analyzed by regular SCEV code.
4327///
4328const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
4329 // Don't attempt to analyze GEPs over unsized objects.
4330 if (!GEP->getSourceElementType()->isSized())
4331 return getUnknown(GEP);
4332
4333 SmallVector<const SCEV *, 4> IndexExprs;
4334 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
4335 IndexExprs.push_back(getSCEV(*Index));
4336 return getGEPExpr(GEP->getSourceElementType(),
4337 getSCEV(GEP->getPointerOperand()),
4338 IndexExprs, GEP->isInBounds());
4339}
4340
4341/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
4342/// guaranteed to end in (at every loop iteration). It is, at the same time,
4343/// the minimum number of times S is divisible by 2. For example, given {4,+,8}
4344/// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S.
4345uint32_t
4346ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
4347 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
4348 return C->getAPInt().countTrailingZeros();
4349
4350 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
4351 return std::min(GetMinTrailingZeros(T->getOperand()),
4352 (uint32_t)getTypeSizeInBits(T->getType()));
4353
4354 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
4355 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
4356 return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
4357 getTypeSizeInBits(E->getType()) : OpRes;
4358 }
4359
4360 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
4361 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
4362 return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
4363 getTypeSizeInBits(E->getType()) : OpRes;
4364 }
4365
4366 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
4367 // The result is the min of all operands results.
4368 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
4369 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
4370 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
4371 return MinOpRes;
4372 }
4373
4374 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
4375 // The result is the sum of all operands results.
4376 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
4377 uint32_t BitWidth = getTypeSizeInBits(M->getType());
4378 for (unsigned i = 1, e = M->getNumOperands();
4379 SumOpRes != BitWidth && i != e; ++i)
4380 SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)),
4381 BitWidth);
4382 return SumOpRes;
4383 }
4384
4385 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
4386 // The result is the min of all operands results.
4387 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
4388 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
4389 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
4390 return MinOpRes;
4391 }
4392
4393 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
4394 // The result is the min of all operands results.
4395 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
4396 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
4397 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
4398 return MinOpRes;
4399 }
4400
4401 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
4402 // The result is the min of all operands results.
4403 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
4404 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
4405 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
4406 return MinOpRes;
4407 }
4408
4409 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
4410 // For a SCEVUnknown, ask ValueTracking.
4411 unsigned BitWidth = getTypeSizeInBits(U->getType());
4412 APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
4413 computeKnownBits(U->getValue(), Zeros, Ones, getDataLayout(), 0, &AC,
4414 nullptr, &DT);
4415 return Zeros.countTrailingOnes();
4416 }
4417
4418 // SCEVUDivExpr
4419 return 0;
4420}
4421
4422/// GetRangeFromMetadata - Helper method to assign a range to V from
4423/// metadata present in the IR.
4424static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
4425 if (Instruction *I = dyn_cast<Instruction>(V))
4426 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
4427 return getConstantRangeFromMetadata(*MD);
4428
4429 return None;
4430}
4431
4432/// getRange - Determine the range for a particular SCEV. If SignHint is
4433/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
4434/// with a "cleaner" unsigned (resp. signed) representation.
4435///
4436ConstantRange
4437ScalarEvolution::getRange(const SCEV *S,
4438 ScalarEvolution::RangeSignHint SignHint) {
4439 DenseMap<const SCEV *, ConstantRange> &Cache =
4440 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
4441 : SignedRanges;
4442
4443 // See if we've computed this range already.
4444 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
4445 if (I != Cache.end())
4446 return I->second;
4447
4448 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
4449 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
4450
4451 unsigned BitWidth = getTypeSizeInBits(S->getType());
4452 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
4453
4454 // If the value has known zeros, the maximum value will have those known zeros
4455 // as well.
4456 uint32_t TZ = GetMinTrailingZeros(S);
4457 if (TZ != 0) {
4458 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
4459 ConservativeResult =
4460 ConstantRange(APInt::getMinValue(BitWidth),
4461 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
4462 else
4463 ConservativeResult = ConstantRange(
4464 APInt::getSignedMinValue(BitWidth),
4465 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
4466 }
4467
4468 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
4469 ConstantRange X = getRange(Add->getOperand(0), SignHint);
4470 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
4471 X = X.add(getRange(Add->getOperand(i), SignHint));
4472 return setRange(Add, SignHint, ConservativeResult.intersectWith(X));
4473 }
4474
4475 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
4476 ConstantRange X = getRange(Mul->getOperand(0), SignHint);
4477 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
4478 X = X.multiply(getRange(Mul->getOperand(i), SignHint));
4479 return setRange(Mul, SignHint, ConservativeResult.intersectWith(X));
4480 }
4481
4482 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
4483 ConstantRange X = getRange(SMax->getOperand(0), SignHint);
4484 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
4485 X = X.smax(getRange(SMax->getOperand(i), SignHint));
4486 return setRange(SMax, SignHint, ConservativeResult.intersectWith(X));
4487 }
4488
4489 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
4490 ConstantRange X = getRange(UMax->getOperand(0), SignHint);
4491 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
4492 X = X.umax(getRange(UMax->getOperand(i), SignHint));
4493 return setRange(UMax, SignHint, ConservativeResult.intersectWith(X));
4494 }
4495
4496 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
4497 ConstantRange X = getRange(UDiv->getLHS(), SignHint);
4498 ConstantRange Y = getRange(UDiv->getRHS(), SignHint);
4499 return setRange(UDiv, SignHint,
4500 ConservativeResult.intersectWith(X.udiv(Y)));
4501 }
4502
4503 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
4504 ConstantRange X = getRange(ZExt->getOperand(), SignHint);
4505 return setRange(ZExt, SignHint,
4506 ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
4507 }
4508
4509 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
4510 ConstantRange X = getRange(SExt->getOperand(), SignHint);
4511 return setRange(SExt, SignHint,
4512 ConservativeResult.intersectWith(X.signExtend(BitWidth)));
4513 }
4514
4515 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
4516 ConstantRange X = getRange(Trunc->getOperand(), SignHint);
4517 return setRange(Trunc, SignHint,
4518 ConservativeResult.intersectWith(X.truncate(BitWidth)));
4519 }
4520
4521 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
4522 // If there's no unsigned wrap, the value will never be less than its
4523 // initial value.
4524 if (AddRec->hasNoUnsignedWrap())
4525 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
4526 if (!C->getValue()->isZero())
4527 ConservativeResult = ConservativeResult.intersectWith(
4528 ConstantRange(C->getAPInt(), APInt(BitWidth, 0)));
4529
4530 // If there's no signed wrap, and all the operands have the same sign or
4531 // zero, the value won't ever change sign.
4532 if (AddRec->hasNoSignedWrap()) {
4533 bool AllNonNeg = true;
4534 bool AllNonPos = true;
4535 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
4536 if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
4537 if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
4538 }
4539 if (AllNonNeg)
4540 ConservativeResult = ConservativeResult.intersectWith(
4541 ConstantRange(APInt(BitWidth, 0),
4542 APInt::getSignedMinValue(BitWidth)));
4543 else if (AllNonPos)
4544 ConservativeResult = ConservativeResult.intersectWith(
4545 ConstantRange(APInt::getSignedMinValue(BitWidth),
4546 APInt(BitWidth, 1)));
4547 }
4548
4549 // TODO: non-affine addrec
4550 if (AddRec->isAffine()) {
4551 const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
4552 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
4553 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
4554 auto RangeFromAffine = getRangeForAffineAR(
4555 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
4556 BitWidth);
4557 if (!RangeFromAffine.isFullSet())
4558 ConservativeResult =
4559 ConservativeResult.intersectWith(RangeFromAffine);
4560
4561 auto RangeFromFactoring = getRangeViaFactoring(
4562 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
4563 BitWidth);
4564 if (!RangeFromFactoring.isFullSet())
4565 ConservativeResult =
4566 ConservativeResult.intersectWith(RangeFromFactoring);
4567 }
4568 }
4569
4570 return setRange(AddRec, SignHint, ConservativeResult);
4571 }
4572
4573 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
4574 // Check if the IR explicitly contains !range metadata.
4575 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
4576 if (MDRange.hasValue())
4577 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue());
4578
4579 // Split here to avoid paying the compile-time cost of calling both
4580 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
4581 // if needed.
4582 const DataLayout &DL = getDataLayout();
4583 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
4584 // For a SCEVUnknown, ask ValueTracking.
4585 APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
4586 computeKnownBits(U->getValue(), Zeros, Ones, DL, 0, &AC, nullptr, &DT);
4587 if (Ones != ~Zeros + 1)
4588 ConservativeResult =
4589 ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1));
4590 } else {
4591 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4592, __PRETTY_FUNCTION__))
4592 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4592, __PRETTY_FUNCTION__))
;
4593 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
4594 if (NS > 1)
4595 ConservativeResult = ConservativeResult.intersectWith(
4596 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
4597 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1));
4598 }
4599
4600 return setRange(U, SignHint, ConservativeResult);
4601 }
4602
4603 return setRange(S, SignHint, ConservativeResult);
4604}
4605
4606ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
4607 const SCEV *Step,
4608 const SCEV *MaxBECount,
4609 unsigned BitWidth) {
4610 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4612, __PRETTY_FUNCTION__))
4611 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4612, __PRETTY_FUNCTION__))
4612 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4612, __PRETTY_FUNCTION__))
;
4613
4614 ConstantRange Result(BitWidth, /* isFullSet = */ true);
4615
4616 // Check for overflow. This must be done with ConstantRange arithmetic
4617 // because we could be called from within the ScalarEvolution overflow
4618 // checking code.
4619
4620 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
4621 ConstantRange MaxBECountRange = getUnsignedRange(MaxBECount);
4622 ConstantRange ZExtMaxBECountRange =
4623 MaxBECountRange.zextOrTrunc(BitWidth * 2 + 1);
4624
4625 ConstantRange StepSRange = getSignedRange(Step);
4626 ConstantRange SExtStepSRange = StepSRange.sextOrTrunc(BitWidth * 2 + 1);
4627
4628 ConstantRange StartURange = getUnsignedRange(Start);
4629 ConstantRange EndURange =
4630 StartURange.add(MaxBECountRange.multiply(StepSRange));
4631
4632 // Check for unsigned overflow.
4633 ConstantRange ZExtStartURange = StartURange.zextOrTrunc(BitWidth * 2 + 1);
4634 ConstantRange ZExtEndURange = EndURange.zextOrTrunc(BitWidth * 2 + 1);
4635 if (ZExtStartURange.add(ZExtMaxBECountRange.multiply(SExtStepSRange)) ==
4636 ZExtEndURange) {
4637 APInt Min = APIntOps::umin(StartURange.getUnsignedMin(),
4638 EndURange.getUnsignedMin());
4639 APInt Max = APIntOps::umax(StartURange.getUnsignedMax(),
4640 EndURange.getUnsignedMax());
4641 bool IsFullRange = Min.isMinValue() && Max.isMaxValue();
4642 if (!IsFullRange)
4643 Result =
4644 Result.intersectWith(ConstantRange(Min, Max + 1));
4645 }
4646
4647 ConstantRange StartSRange = getSignedRange(Start);
4648 ConstantRange EndSRange =
4649 StartSRange.add(MaxBECountRange.multiply(StepSRange));
4650
4651 // Check for signed overflow. This must be done with ConstantRange
4652 // arithmetic because we could be called from within the ScalarEvolution
4653 // overflow checking code.
4654 ConstantRange SExtStartSRange = StartSRange.sextOrTrunc(BitWidth * 2 + 1);
4655 ConstantRange SExtEndSRange = EndSRange.sextOrTrunc(BitWidth * 2 + 1);
4656 if (SExtStartSRange.add(ZExtMaxBECountRange.multiply(SExtStepSRange)) ==
4657 SExtEndSRange) {
4658 APInt Min =
4659 APIntOps::smin(StartSRange.getSignedMin(), EndSRange.getSignedMin());
4660 APInt Max =
4661 APIntOps::smax(StartSRange.getSignedMax(), EndSRange.getSignedMax());
4662 bool IsFullRange = Min.isMinSignedValue() && Max.isMaxSignedValue();
4663 if (!IsFullRange)
4664 Result =
4665 Result.intersectWith(ConstantRange(Min, Max + 1));
4666 }
4667
4668 return Result;
4669}
4670
4671ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
4672 const SCEV *Step,
4673 const SCEV *MaxBECount,
4674 unsigned BitWidth) {
4675 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
4676 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
4677
4678 struct SelectPattern {
4679 Value *Condition = nullptr;
4680 APInt TrueValue;
4681 APInt FalseValue;
4682
4683 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
4684 const SCEV *S) {
4685 Optional<unsigned> CastOp;
4686 APInt Offset(BitWidth, 0);
4687
4688 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4689, __PRETTY_FUNCTION__))
4689 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4689, __PRETTY_FUNCTION__))
;
4690
4691 // Peel off a constant offset:
4692 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
4693 // In the future we could consider being smarter here and handle
4694 // {Start+Step,+,Step} too.
4695 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
4696 return;
4697
4698 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
4699 S = SA->getOperand(1);
4700 }
4701
4702 // Peel off a cast operation
4703 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
4704 CastOp = SCast->getSCEVType();
4705 S = SCast->getOperand();
4706 }
4707
4708 using namespace llvm::PatternMatch;
4709
4710 auto *SU = dyn_cast<SCEVUnknown>(S);
4711 const APInt *TrueVal, *FalseVal;
4712 if (!SU ||
4713 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
4714 m_APInt(FalseVal)))) {
4715 Condition = nullptr;
4716 return;
4717 }
4718
4719 TrueValue = *TrueVal;
4720 FalseValue = *FalseVal;
4721
4722 // Re-apply the cast we peeled off earlier
4723 if (CastOp.hasValue())
4724 switch (*CastOp) {
4725 default:
4726 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 4726)
;
4727
4728 case scTruncate:
4729 TrueValue = TrueValue.trunc(BitWidth);
4730 FalseValue = FalseValue.trunc(BitWidth);
4731 break;
4732 case scZeroExtend:
4733 TrueValue = TrueValue.zext(BitWidth);
4734 FalseValue = FalseValue.zext(BitWidth);
4735 break;
4736 case scSignExtend:
4737 TrueValue = TrueValue.sext(BitWidth);
4738 FalseValue = FalseValue.sext(BitWidth);
4739 break;
4740 }
4741
4742 // Re-apply the constant offset we peeled off earlier
4743 TrueValue += Offset;
4744 FalseValue += Offset;
4745 }
4746
4747 bool isRecognized() { return Condition != nullptr; }
4748 };
4749
4750 SelectPattern StartPattern(*this, BitWidth, Start);
4751 if (!StartPattern.isRecognized())
4752 return ConstantRange(BitWidth, /* isFullSet = */ true);
4753
4754 SelectPattern StepPattern(*this, BitWidth, Step);
4755 if (!StepPattern.isRecognized())
4756 return ConstantRange(BitWidth, /* isFullSet = */ true);
4757
4758 if (StartPattern.Condition != StepPattern.Condition) {
4759 // We don't handle this case today; but we could, by considering four
4760 // possibilities below instead of two. I'm not sure if there are cases where
4761 // that will help over what getRange already does, though.
4762 return ConstantRange(BitWidth, /* isFullSet = */ true);
4763 }
4764
4765 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
4766 // construct arbitrary general SCEV expressions here. This function is called
4767 // from deep in the call stack, and calling getSCEV (on a sext instruction,
4768 // say) can end up caching a suboptimal value.
4769
4770 // FIXME: without the explicit `this` receiver below, MSVC errors out with
4771 // C2352 and C2512 (otherwise it isn't needed).
4772
4773 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
4774 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
4775 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
4776 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
4777
4778 ConstantRange TrueRange =
4779 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
4780 ConstantRange FalseRange =
4781 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
4782
4783 return TrueRange.unionWith(FalseRange);
4784}
4785
4786SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
4787 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
4788 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
4789
4790 // Return early if there are no flags to propagate to the SCEV.
4791 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4792 if (BinOp->hasNoUnsignedWrap())
4793 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
4794 if (BinOp->hasNoSignedWrap())
4795 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
4796 if (Flags == SCEV::FlagAnyWrap)
4797 return SCEV::FlagAnyWrap;
4798
4799 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
4800}
4801
4802bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
4803 // Here we check that I is in the header of the innermost loop containing I,
4804 // since we only deal with instructions in the loop header. The actual loop we
4805 // need to check later will come from an add recurrence, but getting that
4806 // requires computing the SCEV of the operands, which can be expensive. This
4807 // check we can do cheaply to rule out some cases early.
4808 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
4809 if (InnermostContainingLoop == nullptr ||
4810 InnermostContainingLoop->getHeader() != I->getParent())
4811 return false;
4812
4813 // Only proceed if we can prove that I does not yield poison.
4814 if (!isKnownNotFullPoison(I)) return false;
4815
4816 // At this point we know that if I is executed, then it does not wrap
4817 // according to at least one of NSW or NUW. If I is not executed, then we do
4818 // not know if the calculation that I represents would wrap. Multiple
4819 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
4820 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
4821 // derived from other instructions that map to the same SCEV. We cannot make
4822 // that guarantee for cases where I is not executed. So we need to find the
4823 // loop that I is considered in relation to and prove that I is executed for
4824 // every iteration of that loop. That implies that the value that I
4825 // calculates does not wrap anywhere in the loop, so then we can apply the
4826 // flags to the SCEV.
4827 //
4828 // We check isLoopInvariant to disambiguate in case we are adding recurrences
4829 // from different loops, so that we know which loop to prove that I is
4830 // executed in.
4831 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
4832 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
4833 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
4834 bool AllOtherOpsLoopInvariant = true;
4835 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
4836 ++OtherOpIndex) {
4837 if (OtherOpIndex != OpIndex) {
4838 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
4839 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
4840 AllOtherOpsLoopInvariant = false;
4841 break;
4842 }
4843 }
4844 }
4845 if (AllOtherOpsLoopInvariant &&
4846 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
4847 return true;
4848 }
4849 }
4850 return false;
4851}
4852
4853/// createSCEV - We know that there is no SCEV for the specified value. Analyze
4854/// the expression.
4855///
4856const SCEV *ScalarEvolution::createSCEV(Value *V) {
4857 if (!isSCEVable(V->getType()))
4858 return getUnknown(V);
4859
4860 if (Instruction *I = dyn_cast<Instruction>(V)) {
4861 // Don't attempt to analyze instructions in blocks that aren't
4862 // reachable. Such instructions don't matter, and they aren't required
4863 // to obey basic rules for definitions dominating uses which this
4864 // analysis depends on.
4865 if (!DT.isReachableFromEntry(I->getParent()))
4866 return getUnknown(V);
4867 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
4868 return getConstant(CI);
4869 else if (isa<ConstantPointerNull>(V))
4870 return getZero(V->getType());
4871 else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
4872 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
4873 else if (!isa<ConstantExpr>(V))
4874 return getUnknown(V);
4875
4876 Operator *U = cast<Operator>(V);
4877 if (auto BO = MatchBinaryOp(U)) {
4878 switch (BO->Opcode) {
4879 case Instruction::Add: {
4880 // The simple thing to do would be to just call getSCEV on both operands
4881 // and call getAddExpr with the result. However if we're looking at a
4882 // bunch of things all added together, this can be quite inefficient,
4883 // because it leads to N-1 getAddExpr calls for N ultimate operands.
4884 // Instead, gather up all the operands and make a single getAddExpr call.
4885 // LLVM IR canonical form means we need only traverse the left operands.
4886 SmallVector<const SCEV *, 4> AddOps;
4887 do {
4888 if (BO->Op) {
4889 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
4890 AddOps.push_back(OpSCEV);
4891 break;
4892 }
4893
4894 // If a NUW or NSW flag can be applied to the SCEV for this
4895 // addition, then compute the SCEV for this addition by itself
4896 // with a separate call to getAddExpr. We need to do that
4897 // instead of pushing the operands of the addition onto AddOps,
4898 // since the flags are only known to apply to this particular
4899 // addition - they may not apply to other additions that can be
4900 // formed with operands from AddOps.
4901 const SCEV *RHS = getSCEV(BO->RHS);
4902 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
4903 if (Flags != SCEV::FlagAnyWrap) {
4904 const SCEV *LHS = getSCEV(BO->LHS);
4905 if (BO->Opcode == Instruction::Sub)
4906 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
4907 else
4908 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
4909 break;
4910 }
4911 }
4912
4913 if (BO->Opcode == Instruction::Sub)
4914 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
4915 else
4916 AddOps.push_back(getSCEV(BO->RHS));
4917
4918 auto NewBO = MatchBinaryOp(BO->LHS);
4919 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
4920 NewBO->Opcode != Instruction::Sub)) {
4921 AddOps.push_back(getSCEV(BO->LHS));
4922 break;
4923 }
4924 BO = NewBO;
4925 } while (true);
4926
4927 return getAddExpr(AddOps);
4928 }
4929
4930 case Instruction::Mul: {
4931 SmallVector<const SCEV *, 4> MulOps;
4932 do {
4933 if (BO->Op) {
4934 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
4935 MulOps.push_back(OpSCEV);
4936 break;
4937 }
4938
4939 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
4940 if (Flags != SCEV::FlagAnyWrap) {
4941 MulOps.push_back(
4942 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
4943 break;
4944 }
4945 }
4946
4947 MulOps.push_back(getSCEV(BO->RHS));
4948 auto NewBO = MatchBinaryOp(BO->LHS);
4949 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
4950 MulOps.push_back(getSCEV(BO->LHS));
4951 break;
4952 }
4953 BO = NewBO;
4954 } while (true);
4955
4956 return getMulExpr(MulOps);
4957 }
4958 case Instruction::UDiv:
4959 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
4960 case Instruction::Sub: {
4961 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4962 if (BO->Op)
4963 Flags = getNoWrapFlagsFromUB(BO->Op);
4964 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
4965 }
4966 case Instruction::And:
4967 // For an expression like x&255 that merely masks off the high bits,
4968 // use zext(trunc(x)) as the SCEV expression.
4969 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
4970 if (CI->isNullValue())
4971 return getSCEV(BO->RHS);
4972 if (CI->isAllOnesValue())
4973 return getSCEV(BO->LHS);
4974 const APInt &A = CI->getValue();
4975
4976 // Instcombine's ShrinkDemandedConstant may strip bits out of
4977 // constants, obscuring what would otherwise be a low-bits mask.
4978 // Use computeKnownBits to compute what ShrinkDemandedConstant
4979 // knew about to reconstruct a low-bits mask value.
4980 unsigned LZ = A.countLeadingZeros();
4981 unsigned TZ = A.countTrailingZeros();
4982 unsigned BitWidth = A.getBitWidth();
4983 APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
4984 computeKnownBits(BO->LHS, KnownZero, KnownOne, getDataLayout(),
4985 0, &AC, nullptr, &DT);
4986
4987 APInt EffectiveMask =
4988 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
4989 if ((LZ != 0 || TZ != 0) && !((~A & ~KnownZero) & EffectiveMask)) {
4990 const SCEV *MulCount = getConstant(ConstantInt::get(
4991 getContext(), APInt::getOneBitSet(BitWidth, TZ)));
4992 return getMulExpr(
4993 getZeroExtendExpr(
4994 getTruncateExpr(
4995 getUDivExactExpr(getSCEV(BO->LHS), MulCount),
4996 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
4997 BO->LHS->getType()),
4998 MulCount);
4999 }
5000 }
5001 break;
5002
5003 case Instruction::Or:
5004 // If the RHS of the Or is a constant, we may have something like:
5005 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
5006 // optimizations will transparently handle this case.
5007 //
5008 // In order for this transformation to be safe, the LHS must be of the
5009 // form X*(2^n) and the Or constant must be less than 2^n.
5010 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5011 const SCEV *LHS = getSCEV(BO->LHS);
5012 const APInt &CIVal = CI->getValue();
5013 if (GetMinTrailingZeros(LHS) >=
5014 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
5015 // Build a plain add SCEV.
5016 const SCEV *S = getAddExpr(LHS, getSCEV(CI));
5017 // If the LHS of the add was an addrec and it has no-wrap flags,
5018 // transfer the no-wrap flags, since an or won't introduce a wrap.
5019 if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
5020 const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
5021 const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
5022 OldAR->getNoWrapFlags());
5023 }
5024 return S;
5025 }
5026 }
5027 break;
5028
5029 case Instruction::Xor:
5030 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5031 // If the RHS of xor is -1, then this is a not operation.
5032 if (CI->isAllOnesValue())
5033 return getNotSCEV(getSCEV(BO->LHS));
5034
5035 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
5036 // This is a variant of the check for xor with -1, and it handles
5037 // the case where instcombine has trimmed non-demanded bits out
5038 // of an xor with -1.
5039 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
5040 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
5041 if (LBO->getOpcode() == Instruction::And &&
5042 LCI->getValue() == CI->getValue())
5043 if (const SCEVZeroExtendExpr *Z =
5044 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
5045 Type *UTy = BO->LHS->getType();
5046 const SCEV *Z0 = Z->getOperand();
5047 Type *Z0Ty = Z0->getType();
5048 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
5049
5050 // If C is a low-bits mask, the zero extend is serving to
5051 // mask off the high bits. Complement the operand and
5052 // re-apply the zext.
5053 if (APIntOps::isMask(Z0TySize, CI->getValue()))
5054 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
5055
5056 // If C is a single bit, it may be in the sign-bit position
5057 // before the zero-extend. In this case, represent the xor
5058 // using an add, which is equivalent, and re-apply the zext.
5059 APInt Trunc = CI->getValue().trunc(Z0TySize);
5060 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
5061 Trunc.isSignBit())
5062 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
5063 UTy);
5064 }
5065 }
5066 break;
5067
5068 case Instruction::Shl:
5069 // Turn shift left of a constant amount into a multiply.
5070 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
5071 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
5072
5073 // If the shift count is not less than the bitwidth, the result of
5074 // the shift is undefined. Don't try to analyze it, because the
5075 // resolution chosen here may differ from the resolution chosen in
5076 // other parts of the compiler.
5077 if (SA->getValue().uge(BitWidth))
5078 break;
5079
5080 // It is currently not resolved how to interpret NSW for left
5081 // shift by BitWidth - 1, so we avoid applying flags in that
5082 // case. Remove this check (or this comment) once the situation
5083 // is resolved. See
5084 // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html
5085 // and http://reviews.llvm.org/D8890 .
5086 auto Flags = SCEV::FlagAnyWrap;
5087 if (BO->Op && SA->getValue().ult(BitWidth - 1))
5088 Flags = getNoWrapFlagsFromUB(BO->Op);
5089
5090 Constant *X = ConstantInt::get(getContext(),
5091 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
5092 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
5093 }
5094 break;
5095
5096 case Instruction::AShr:
5097 // For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression.
5098 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS))
5099 if (Operator *L = dyn_cast<Operator>(BO->LHS))
5100 if (L->getOpcode() == Instruction::Shl &&
5101 L->getOperand(1) == BO->RHS) {
5102 uint64_t BitWidth = getTypeSizeInBits(BO->LHS->getType());
5103
5104 // If the shift count is not less than the bitwidth, the result of
5105 // the shift is undefined. Don't try to analyze it, because the
5106 // resolution chosen here may differ from the resolution chosen in
5107 // other parts of the compiler.
5108 if (CI->getValue().uge(BitWidth))
5109 break;
5110
5111 uint64_t Amt = BitWidth - CI->getZExtValue();
5112 if (Amt == BitWidth)
5113 return getSCEV(L->getOperand(0)); // shift by zero --> noop
5114 return getSignExtendExpr(
5115 getTruncateExpr(getSCEV(L->getOperand(0)),
5116 IntegerType::get(getContext(), Amt)),
5117 BO->LHS->getType());
5118 }
5119 break;
5120 }
5121 }
5122
5123 switch (U->getOpcode()) {
5124 case Instruction::Trunc:
5125 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
5126
5127 case Instruction::ZExt:
5128 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
5129
5130 case Instruction::SExt:
5131 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
5132
5133 case Instruction::BitCast:
5134 // BitCasts are no-op casts so we just eliminate the cast.
5135 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
5136 return getSCEV(U->getOperand(0));
5137 break;
5138
5139 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
5140 // lead to pointer expressions which cannot safely be expanded to GEPs,
5141 // because ScalarEvolution doesn't respect the GEP aliasing rules when
5142 // simplifying integer expressions.
5143
5144 case Instruction::GetElementPtr:
5145 return createNodeForGEP(cast<GEPOperator>(U));
5146
5147 case Instruction::PHI:
5148 return createNodeForPHI(cast<PHINode>(U));
5149
5150 case Instruction::Select:
5151 // U can also be a select constant expr, which let fall through. Since
5152 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
5153 // constant expressions cannot have instructions as operands, we'd have
5154 // returned getUnknown for a select constant expressions anyway.
5155 if (isa<Instruction>(U))
5156 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
5157 U->getOperand(1), U->getOperand(2));
5158 }
5159
5160 return getUnknown(V);
5161}
5162
5163
5164
5165//===----------------------------------------------------------------------===//
5166// Iteration Count Computation Code
5167//
5168
5169unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L) {
5170 if (BasicBlock *ExitingBB = L->getExitingBlock())
5171 return getSmallConstantTripCount(L, ExitingBB);
5172
5173 // No trip count information for multiple exits.
5174 return 0;
5175}
5176
5177/// getSmallConstantTripCount - Returns the maximum trip count of this loop as a
5178/// normal unsigned value. Returns 0 if the trip count is unknown or not
5179/// constant. Will also return 0 if the maximum trip count is very large (>=
5180/// 2^32).
5181///
5182/// This "trip count" assumes that control exits via ExitingBlock. More
5183/// precisely, it is the number of times that control may reach ExitingBlock
5184/// before taking the branch. For loops with multiple exits, it may not be the
5185/// number times that the loop header executes because the loop may exit
5186/// prematurely via another branch.
5187unsigned ScalarEvolution::getSmallConstantTripCount(Loop *L,
5188 BasicBlock *ExitingBlock) {
5189 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5189, __PRETTY_FUNCTION__))
;
5190 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5191, __PRETTY_FUNCTION__))
5191 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5191, __PRETTY_FUNCTION__))
;
5192 const SCEVConstant *ExitCount =
5193 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
5194 if (!ExitCount)
5195 return 0;
5196
5197 ConstantInt *ExitConst = ExitCount->getValue();
5198
5199 // Guard against huge trip counts.
5200 if (ExitConst->getValue().getActiveBits() > 32)
5201 return 0;
5202
5203 // In case of integer overflow, this returns 0, which is correct.
5204 return ((unsigned)ExitConst->getZExtValue()) + 1;
5205}
5206
5207unsigned ScalarEvolution::getSmallConstantTripMultiple(Loop *L) {
5208 if (BasicBlock *ExitingBB = L->getExitingBlock())
5209 return getSmallConstantTripMultiple(L, ExitingBB);
5210
5211 // No trip multiple information for multiple exits.
5212 return 0;
5213}
5214
5215/// getSmallConstantTripMultiple - Returns the largest constant divisor of the
5216/// trip count of this loop as a normal unsigned value, if possible. This
5217/// means that the actual trip count is always a multiple of the returned
5218/// value (don't forget the trip count could very well be zero as well!).
5219///
5220/// Returns 1 if the trip count is unknown or not guaranteed to be the
5221/// multiple of a constant (which is also the case if the trip count is simply
5222/// constant, use getSmallConstantTripCount for that case), Will also return 1
5223/// if the trip count is very large (>= 2^32).
5224///
5225/// As explained in the comments for getSmallConstantTripCount, this assumes
5226/// that control exits the loop via ExitingBlock.
5227unsigned
5228ScalarEvolution::getSmallConstantTripMultiple(Loop *L,
5229 BasicBlock *ExitingBlock) {
5230 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5230, __PRETTY_FUNCTION__))
;
5231 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5232, __PRETTY_FUNCTION__))
5232 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5232, __PRETTY_FUNCTION__))
;
5233 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
5234 if (ExitCount == getCouldNotCompute())
5235 return 1;
5236
5237 // Get the trip count from the BE count by adding 1.
5238 const SCEV *TCMul = getAddExpr(ExitCount, getOne(ExitCount->getType()));
5239 // FIXME: SCEV distributes multiplication as V1*C1 + V2*C1. We could attempt
5240 // to factor simple cases.
5241 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(TCMul))
5242 TCMul = Mul->getOperand(0);
5243
5244 const SCEVConstant *MulC = dyn_cast<SCEVConstant>(TCMul);
5245 if (!MulC)
5246 return 1;
5247
5248 ConstantInt *Result = MulC->getValue();
5249
5250 // Guard against huge trip counts (this requires checking
5251 // for zero to handle the case where the trip count == -1 and the
5252 // addition wraps).
5253 if (!Result || Result->getValue().getActiveBits() > 32 ||
5254 Result->getValue().getActiveBits() == 0)
5255 return 1;
5256
5257 return (unsigned)Result->getZExtValue();
5258}
5259
5260// getExitCount - Get the expression for the number of loop iterations for which
5261// this loop is guaranteed not to exit via ExitingBlock. Otherwise return
5262// SCEVCouldNotCompute.
5263const SCEV *ScalarEvolution::getExitCount(Loop *L, BasicBlock *ExitingBlock) {
5264 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
5265}
5266
5267const SCEV *
5268ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
5269 SCEVUnionPredicate &Preds) {
5270 return getPredicatedBackedgeTakenInfo(L).getExact(this, &Preds);
5271}
5272
5273/// getBackedgeTakenCount - If the specified loop has a predictable
5274/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
5275/// object. The backedge-taken count is the number of times the loop header
5276/// will be branched to from within the loop. This is one less than the
5277/// trip count of the loop, since it doesn't count the first iteration,
5278/// when the header is branched to from outside the loop.
5279///
5280/// Note that it is not valid to call this method on a loop without a
5281/// loop-invariant backedge-taken count (see
5282/// hasLoopInvariantBackedgeTakenCount).
5283///
5284const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
5285 return getBackedgeTakenInfo(L).getExact(this);
5286}
5287
5288/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
5289/// return the least SCEV value that is known never to be less than the
5290/// actual backedge taken count.
5291const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
5292 return getBackedgeTakenInfo(L).getMax(this);
5293}
5294
5295/// PushLoopPHIs - Push PHI nodes in the header of the given loop
5296/// onto the given Worklist.
5297static void
5298PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
5299 BasicBlock *Header = L->getHeader();
5300
5301 // Push all Loop-header PHIs onto the Worklist stack.
5302 for (BasicBlock::iterator I = Header->begin();
5303 PHINode *PN = dyn_cast<PHINode>(I); ++I)
5304 Worklist.push_back(PN);
5305}
5306
5307const ScalarEvolution::BackedgeTakenInfo &
5308ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
5309 auto &BTI = getBackedgeTakenInfo(L);
5310 if (BTI.hasFullInfo())
5311 return BTI;
5312
5313 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
5314
5315 if (!Pair.second)
5316 return Pair.first->second;
5317
5318 BackedgeTakenInfo Result =
5319 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
5320
5321 return PredicatedBackedgeTakenCounts.find(L)->second = Result;
5322}
5323
5324const ScalarEvolution::BackedgeTakenInfo &
5325ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
5326 // Initially insert an invalid entry for this loop. If the insertion
5327 // succeeds, proceed to actually compute a backedge-taken count and
5328 // update the value. The temporary CouldNotCompute value tells SCEV
5329 // code elsewhere that it shouldn't attempt to request a new
5330 // backedge-taken count, which could result in infinite recursion.
5331 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
5332 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
5333 if (!Pair.second)
5334 return Pair.first->second;
5335
5336 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
5337 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
5338 // must be cleared in this scope.
5339 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
5340
5341 if (Result.getExact(this) != getCouldNotCompute()) {
5342 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5344, __PRETTY_FUNCTION__))
5343 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5344, __PRETTY_FUNCTION__))
5344 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5344, __PRETTY_FUNCTION__))
;
5345 ++NumTripCountsComputed;
5346 }
5347 else if (Result.getMax(this) == getCouldNotCompute() &&
5348 isa<PHINode>(L->getHeader()->begin())) {
5349 // Only count loops that have phi nodes as not being computable.
5350 ++NumTripCountsNotComputed;
5351 }
5352
5353 // Now that we know more about the trip count for this loop, forget any
5354 // existing SCEV values for PHI nodes in this loop since they are only
5355 // conservative estimates made without the benefit of trip count
5356 // information. This is similar to the code in forgetLoop, except that
5357 // it handles SCEVUnknown PHI nodes specially.
5358 if (Result.hasAnyInfo()) {
5359 SmallVector<Instruction *, 16> Worklist;
5360 PushLoopPHIs(L, Worklist);
5361
5362 SmallPtrSet<Instruction *, 8> Visited;
5363 while (!Worklist.empty()) {
5364 Instruction *I = Worklist.pop_back_val();
5365 if (!Visited.insert(I).second)
5366 continue;
5367
5368 ValueExprMapType::iterator It =
5369 ValueExprMap.find_as(static_cast<Value *>(I));
5370 if (It != ValueExprMap.end()) {
5371 const SCEV *Old = It->second;
5372
5373 // SCEVUnknown for a PHI either means that it has an unrecognized
5374 // structure, or it's a PHI that's in the progress of being computed
5375 // by createNodeForPHI. In the former case, additional loop trip
5376 // count information isn't going to change anything. In the later
5377 // case, createNodeForPHI will perform the necessary updates on its
5378 // own when it gets to that point.
5379 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
5380 forgetMemoizedResults(Old);
5381 ValueExprMap.erase(It);
5382 }
5383 if (PHINode *PN = dyn_cast<PHINode>(I))
5384 ConstantEvolutionLoopExitValue.erase(PN);
5385 }
5386
5387 PushDefUseChildren(I, Worklist);
5388 }
5389 }
5390
5391 // Re-lookup the insert position, since the call to
5392 // computeBackedgeTakenCount above could result in a
5393 // recusive call to getBackedgeTakenInfo (on a different
5394 // loop), which would invalidate the iterator computed
5395 // earlier.
5396 return BackedgeTakenCounts.find(L)->second = Result;
5397}
5398
5399/// forgetLoop - This method should be called by the client when it has
5400/// changed a loop in a way that may effect ScalarEvolution's ability to
5401/// compute a trip count, or if the loop is deleted.
5402void ScalarEvolution::forgetLoop(const Loop *L) {
5403 // Drop any stored trip count value.
5404 auto RemoveLoopFromBackedgeMap =
5405 [L](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
5406 auto BTCPos = Map.find(L);
5407 if (BTCPos != Map.end()) {
5408 BTCPos->second.clear();
5409 Map.erase(BTCPos);
5410 }
5411 };
5412
5413 RemoveLoopFromBackedgeMap(BackedgeTakenCounts);
5414 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts);
5415
5416 // Drop information about expressions based on loop-header PHIs.
5417 SmallVector<Instruction *, 16> Worklist;
5418 PushLoopPHIs(L, Worklist);
5419
5420 SmallPtrSet<Instruction *, 8> Visited;
5421 while (!Worklist.empty()) {
5422 Instruction *I = Worklist.pop_back_val();
5423 if (!Visited.insert(I).second)
5424 continue;
5425
5426 ValueExprMapType::iterator It =
5427 ValueExprMap.find_as(static_cast<Value *>(I));
5428 if (It != ValueExprMap.end()) {
5429 forgetMemoizedResults(It->second);
5430 ValueExprMap.erase(It);
5431 if (PHINode *PN = dyn_cast<PHINode>(I))
5432 ConstantEvolutionLoopExitValue.erase(PN);
5433 }
5434
5435 PushDefUseChildren(I, Worklist);
5436 }
5437
5438 // Forget all contained loops too, to avoid dangling entries in the
5439 // ValuesAtScopes map.
5440 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
5441 forgetLoop(*I);
5442}
5443
5444/// forgetValue - This method should be called by the client when it has
5445/// changed a value in a way that may effect its value, or which may
5446/// disconnect it from a def-use chain linking it to a loop.
5447void ScalarEvolution::forgetValue(Value *V) {
5448 Instruction *I = dyn_cast<Instruction>(V);
5449 if (!I) return;
5450
5451 // Drop information about expressions based on loop-header PHIs.
5452 SmallVector<Instruction *, 16> Worklist;
5453 Worklist.push_back(I);
5454
5455 SmallPtrSet<Instruction *, 8> Visited;
5456 while (!Worklist.empty()) {
5457 I = Worklist.pop_back_val();
5458 if (!Visited.insert(I).second)
5459 continue;
5460
5461 ValueExprMapType::iterator It =
5462 ValueExprMap.find_as(static_cast<Value *>(I));
5463 if (It != ValueExprMap.end()) {
5464 forgetMemoizedResults(It->second);
5465 ValueExprMap.erase(It);
5466 if (PHINode *PN = dyn_cast<PHINode>(I))
5467 ConstantEvolutionLoopExitValue.erase(PN);
5468 }
5469
5470 PushDefUseChildren(I, Worklist);
5471 }
5472}
5473
5474/// getExact - Get the exact loop backedge taken count considering all loop
5475/// exits. A computable result can only be returned for loops with a single
5476/// exit. Returning the minimum taken count among all exits is incorrect
5477/// because one of the loop's exit limit's may have been skipped. HowFarToZero
5478/// assumes that the limit of each loop test is never skipped. This is a valid
5479/// assumption as long as the loop exits via that test. For precise results, it
5480/// is the caller's responsibility to specify the relevant loop exit using
5481/// getExact(ExitingBlock, SE).
5482const SCEV *
5483ScalarEvolution::BackedgeTakenInfo::getExact(
5484 ScalarEvolution *SE, SCEVUnionPredicate *Preds) const {
5485 // If any exits were not computable, the loop is not computable.
5486 if (!ExitNotTaken.isCompleteList()) return SE->getCouldNotCompute();
5487
5488 // We need exactly one computable exit.
5489 if (!ExitNotTaken.ExitingBlock) return SE->getCouldNotCompute();
5490 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5490, __PRETTY_FUNCTION__))
;
5491
5492 const SCEV *BECount = nullptr;
5493 for (auto &ENT : ExitNotTaken) {
5494 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5494, __PRETTY_FUNCTION__))
;
5495
5496 if (!BECount)
5497 BECount = ENT.ExactNotTaken;
5498 else if (BECount != ENT.ExactNotTaken)
5499 return SE->getCouldNotCompute();
5500 if (Preds && ENT.getPred())
5501 Preds->add(ENT.getPred());
5502
5503 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5504, __PRETTY_FUNCTION__))
5504 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5504, __PRETTY_FUNCTION__))
;
5505 }
5506
5507 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5507, __PRETTY_FUNCTION__))
;
5508 return BECount;
5509}
5510
5511/// getExact - Get the exact not taken count for this loop exit.
5512const SCEV *
5513ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
5514 ScalarEvolution *SE) const {
5515 for (auto &ENT : ExitNotTaken)
5516 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePred())
5517 return ENT.ExactNotTaken;
5518
5519 return SE->getCouldNotCompute();
5520}
5521
5522/// getMax - Get the max backedge taken count for the loop.
5523const SCEV *
5524ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
5525 for (auto &ENT : ExitNotTaken)
5526 if (!ENT.hasAlwaysTruePred())
5527 return SE->getCouldNotCompute();
5528
5529 return Max ? Max : SE->getCouldNotCompute();
5530}
5531
5532bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
5533 ScalarEvolution *SE) const {
5534 if (Max && Max != SE->getCouldNotCompute() && SE->hasOperand(Max, S))
5535 return true;
5536
5537 if (!ExitNotTaken.ExitingBlock)
5538 return false;
5539
5540 for (auto &ENT : ExitNotTaken)
5541 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
5542 SE->hasOperand(ENT.ExactNotTaken, S))
5543 return true;
5544
5545 return false;
5546}
5547
5548/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
5549/// computable exit into a persistent ExitNotTakenInfo array.
5550ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
5551 SmallVectorImpl<EdgeInfo> &ExitCounts, bool Complete, const SCEV *MaxCount)
5552 : Max(MaxCount) {
5553
5554 if (!Complete)
5555 ExitNotTaken.setIncomplete();
5556
5557 unsigned NumExits = ExitCounts.size();
5558 if (NumExits == 0) return;
5559
5560 ExitNotTaken.ExitingBlock = ExitCounts[0].ExitBlock;
5561 ExitNotTaken.ExactNotTaken = ExitCounts[0].Taken;
5562
5563 // Determine the number of ExitNotTakenExtras structures that we need.
5564 unsigned ExtraInfoSize = 0;
5565 if (NumExits > 1)
5566 ExtraInfoSize = 1 + std::count_if(std::next(ExitCounts.begin()),
5567 ExitCounts.end(), [](EdgeInfo &Entry) {
5568 return !Entry.Pred.isAlwaysTrue();
5569 });
5570 else if (!ExitCounts[0].Pred.isAlwaysTrue())
5571 ExtraInfoSize = 1;
5572
5573 ExitNotTakenExtras *ENT = nullptr;
5574
5575 // Allocate the ExitNotTakenExtras structures and initialize the first
5576 // element (ExitNotTaken).
5577 if (ExtraInfoSize > 0) {
5578 ENT = new ExitNotTakenExtras[ExtraInfoSize];
5579 ExitNotTaken.ExtraInfo = &ENT[0];
5580 *ExitNotTaken.getPred() = std::move(ExitCounts[0].Pred);
5581 }
5582
5583 if (NumExits == 1)
5584 return;
5585
5586 assert(ENT && "ExitNotTakenExtras is NULL while having more than one exit")((ENT && "ExitNotTakenExtras is NULL while having more than one exit"
) ? static_cast<void> (0) : __assert_fail ("ENT && \"ExitNotTakenExtras is NULL while having more than one exit\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5586, __PRETTY_FUNCTION__))
;
5587
5588 auto &Exits = ExitNotTaken.ExtraInfo->Exits;
5589
5590 // Handle the rare case of multiple computable exits.
5591 for (unsigned i = 1, PredPos = 1; i < NumExits; ++i) {
5592 ExitNotTakenExtras *Ptr = nullptr;
5593 if (!ExitCounts[i].Pred.isAlwaysTrue()) {
5594 Ptr = &ENT[PredPos++];
5595 Ptr->Pred = std::move(ExitCounts[i].Pred);
5596 }
5597
5598 Exits.emplace_back(ExitCounts[i].ExitBlock, ExitCounts[i].Taken, Ptr);
5599 }
5600}
5601
5602/// clear - Invalidate this result and free the ExitNotTakenInfo array.
5603void ScalarEvolution::BackedgeTakenInfo::clear() {
5604 ExitNotTaken.ExitingBlock = nullptr;
5605 ExitNotTaken.ExactNotTaken = nullptr;
5606 delete[] ExitNotTaken.ExtraInfo;
5607}
5608
5609/// computeBackedgeTakenCount - Compute the number of times the backedge
5610/// of the specified loop will execute.
5611ScalarEvolution::BackedgeTakenInfo
5612ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
5613 bool AllowPredicates) {
5614 SmallVector<BasicBlock *, 8> ExitingBlocks;
5615 L->getExitingBlocks(ExitingBlocks);
5616
5617 SmallVector<EdgeInfo, 4> ExitCounts;
5618 bool CouldComputeBECount = true;
5619 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
5620 const SCEV *MustExitMaxBECount = nullptr;
5621 const SCEV *MayExitMaxBECount = nullptr;
5622
5623 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
5624 // and compute maxBECount.
5625 // Do a union of all the predicates here.
5626 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
5627 BasicBlock *ExitBB = ExitingBlocks[i];
5628 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
5629
5630 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5631, __PRETTY_FUNCTION__))
5631 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5631, __PRETTY_FUNCTION__))
;
5632
5633 // 1. For each exit that can be computed, add an entry to ExitCounts.
5634 // CouldComputeBECount is true only if all exits can be computed.
5635 if (EL.Exact == getCouldNotCompute())
5636 // We couldn't compute an exact value for this exit, so
5637 // we won't be able to compute an exact value for the loop.
5638 CouldComputeBECount = false;
5639 else
5640 ExitCounts.emplace_back(EdgeInfo(ExitBB, EL.Exact, EL.Pred));
5641
5642 // 2. Derive the loop's MaxBECount from each exit's max number of
5643 // non-exiting iterations. Partition the loop exits into two kinds:
5644 // LoopMustExits and LoopMayExits.
5645 //
5646 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
5647 // is a LoopMayExit. If any computable LoopMustExit is found, then
5648 // MaxBECount is the minimum EL.Max of computable LoopMustExits. Otherwise,
5649 // MaxBECount is conservatively the maximum EL.Max, where CouldNotCompute is
5650 // considered greater than any computable EL.Max.
5651 if (EL.Max != getCouldNotCompute() && Latch &&
5652 DT.dominates(ExitBB, Latch)) {
5653 if (!MustExitMaxBECount)
5654 MustExitMaxBECount = EL.Max;
5655 else {
5656 MustExitMaxBECount =
5657 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.Max);
5658 }
5659 } else if (MayExitMaxBECount != getCouldNotCompute()) {
5660 if (!MayExitMaxBECount || EL.Max == getCouldNotCompute())
5661 MayExitMaxBECount = EL.Max;
5662 else {
5663 MayExitMaxBECount =
5664 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.Max);
5665 }
5666 }
5667 }
5668 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
5669 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
5670 return BackedgeTakenInfo(ExitCounts, CouldComputeBECount, MaxBECount);
5671}
5672
5673ScalarEvolution::ExitLimit
5674ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
5675 bool AllowPredicates) {
5676
5677 // Okay, we've chosen an exiting block. See what condition causes us to exit
5678 // at this block and remember the exit block and whether all other targets
5679 // lead to the loop header.
5680 bool MustExecuteLoopHeader = true;
5681 BasicBlock *Exit = nullptr;
5682 for (auto *SBB : successors(ExitingBlock))
5683 if (!L->contains(SBB)) {
5684 if (Exit) // Multiple exit successors.
5685 return getCouldNotCompute();
5686 Exit = SBB;
5687 } else if (SBB != L->getHeader()) {
5688 MustExecuteLoopHeader = false;
5689 }
5690
5691 // At this point, we know we have a conditional branch that determines whether
5692 // the loop is exited. However, we don't know if the branch is executed each
5693 // time through the loop. If not, then the execution count of the branch will
5694 // not be equal to the trip count of the loop.
5695 //
5696 // Currently we check for this by checking to see if the Exit branch goes to
5697 // the loop header. If so, we know it will always execute the same number of
5698 // times as the loop. We also handle the case where the exit block *is* the
5699 // loop header. This is common for un-rotated loops.
5700 //
5701 // If both of those tests fail, walk up the unique predecessor chain to the
5702 // header, stopping if there is an edge that doesn't exit the loop. If the
5703 // header is reached, the execution count of the branch will be equal to the
5704 // trip count of the loop.
5705 //
5706 // More extensive analysis could be done to handle more cases here.
5707 //
5708 if (!MustExecuteLoopHeader && ExitingBlock != L->getHeader()) {
5709 // The simple checks failed, try climbing the unique predecessor chain
5710 // up to the header.
5711 bool Ok = false;
5712 for (BasicBlock *BB = ExitingBlock; BB; ) {
5713 BasicBlock *Pred = BB->getUniquePredecessor();
5714 if (!Pred)
5715 return getCouldNotCompute();
5716 TerminatorInst *PredTerm = Pred->getTerminator();
5717 for (const BasicBlock *PredSucc : PredTerm->successors()) {
5718 if (PredSucc == BB)
5719 continue;
5720 // If the predecessor has a successor that isn't BB and isn't
5721 // outside the loop, assume the worst.
5722 if (L->contains(PredSucc))
5723 return getCouldNotCompute();
5724 }
5725 if (Pred == L->getHeader()) {
5726 Ok = true;
5727 break;
5728 }
5729 BB = Pred;
5730 }
5731 if (!Ok)
5732 return getCouldNotCompute();
5733 }
5734
5735 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
5736 TerminatorInst *Term = ExitingBlock->getTerminator();
5737 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
5738 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5738, __PRETTY_FUNCTION__))
;
5739 // Proceed to the next level to examine the exit condition expression.
5740 return computeExitLimitFromCond(
5741 L, BI->getCondition(), BI->getSuccessor(0), BI->getSuccessor(1),
5742 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
5743 }
5744
5745 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term))
5746 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
5747 /*ControlsExit=*/IsOnlyExit);
5748
5749 return getCouldNotCompute();
5750}
5751
5752/// computeExitLimitFromCond - Compute the number of times the
5753/// backedge of the specified loop will execute if its exit condition
5754/// were a conditional branch of ExitCond, TBB, and FBB.
5755///
5756/// @param ControlsExit is true if ExitCond directly controls the exit
5757/// branch. In this case, we can assume that the loop exits only if the
5758/// condition is true and can infer that failing to meet the condition prior to
5759/// integer wraparound results in undefined behavior.
5760ScalarEvolution::ExitLimit
5761ScalarEvolution::computeExitLimitFromCond(const Loop *L,
5762 Value *ExitCond,
5763 BasicBlock *TBB,
5764 BasicBlock *FBB,
5765 bool ControlsExit,
5766 bool AllowPredicates) {
5767 // Check if the controlling expression for this loop is an And or Or.
5768 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
5769 if (BO->getOpcode() == Instruction::And) {
5770 // Recurse on the operands of the and.
5771 bool EitherMayExit = L->contains(TBB);
5772 ExitLimit EL0 = computeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB,
5773 ControlsExit && !EitherMayExit,
5774 AllowPredicates);
5775 ExitLimit EL1 = computeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB,
5776 ControlsExit && !EitherMayExit,
5777 AllowPredicates);
5778 const SCEV *BECount = getCouldNotCompute();
5779 const SCEV *MaxBECount = getCouldNotCompute();
5780 if (EitherMayExit) {
5781 // Both conditions must be true for the loop to continue executing.
5782 // Choose the less conservative count.
5783 if (EL0.Exact == getCouldNotCompute() ||
5784 EL1.Exact == getCouldNotCompute())
5785 BECount = getCouldNotCompute();
5786 else
5787 BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
5788 if (EL0.Max == getCouldNotCompute())
5789 MaxBECount = EL1.Max;
5790 else if (EL1.Max == getCouldNotCompute())
5791 MaxBECount = EL0.Max;
5792 else
5793 MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
5794 } else {
5795 // Both conditions must be true at the same time for the loop to exit.
5796 // For now, be conservative.
5797 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5797, __PRETTY_FUNCTION__))
;
5798 if (EL0.Max == EL1.Max)
5799 MaxBECount = EL0.Max;
5800 if (EL0.Exact == EL1.Exact)
5801 BECount = EL0.Exact;
5802 }
5803
5804 SCEVUnionPredicate NP;
5805 NP.add(&EL0.Pred);
5806 NP.add(&EL1.Pred);
5807 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
5808 // to be more aggressive when computing BECount than when computing
5809 // MaxBECount. In these cases it is possible for EL0.Exact and EL1.Exact
5810 // to match, but for EL0.Max and EL1.Max to not.
5811 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
5812 !isa<SCEVCouldNotCompute>(BECount))
5813 MaxBECount = BECount;
5814
5815 return ExitLimit(BECount, MaxBECount, NP);
5816 }
5817 if (BO->getOpcode() == Instruction::Or) {
5818 // Recurse on the operands of the or.
5819 bool EitherMayExit = L->contains(FBB);
5820 ExitLimit EL0 = computeExitLimitFromCond(L, BO->getOperand(0), TBB, FBB,
5821 ControlsExit && !EitherMayExit,
5822 AllowPredicates);
5823 ExitLimit EL1 = computeExitLimitFromCond(L, BO->getOperand(1), TBB, FBB,
5824 ControlsExit && !EitherMayExit,
5825 AllowPredicates);
5826 const SCEV *BECount = getCouldNotCompute();
5827 const SCEV *MaxBECount = getCouldNotCompute();
5828 if (EitherMayExit) {
5829 // Both conditions must be false for the loop to continue executing.
5830 // Choose the less conservative count.
5831 if (EL0.Exact == getCouldNotCompute() ||
5832 EL1.Exact == getCouldNotCompute())
5833 BECount = getCouldNotCompute();
5834 else
5835 BECount = getUMinFromMismatchedTypes(EL0.Exact, EL1.Exact);
5836 if (EL0.Max == getCouldNotCompute())
5837 MaxBECount = EL1.Max;
5838 else if (EL1.Max == getCouldNotCompute())
5839 MaxBECount = EL0.Max;
5840 else
5841 MaxBECount = getUMinFromMismatchedTypes(EL0.Max, EL1.Max);
5842 } else {
5843 // Both conditions must be false at the same time for the loop to exit.
5844 // For now, be conservative.
5845 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5845, __PRETTY_FUNCTION__))
;
5846 if (EL0.Max == EL1.Max)
5847 MaxBECount = EL0.Max;
5848 if (EL0.Exact == EL1.Exact)
5849 BECount = EL0.Exact;
5850 }
5851
5852 SCEVUnionPredicate NP;
5853 NP.add(&EL0.Pred);
5854 NP.add(&EL1.Pred);
5855 return ExitLimit(BECount, MaxBECount, NP);
5856 }
5857 }
5858
5859 // With an icmp, it may be feasible to compute an exact backedge-taken count.
5860 // Proceed to the next level to examine the icmp.
5861 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
5862 ExitLimit EL =
5863 computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit);
5864 if (EL.hasFullInfo() || !AllowPredicates)
5865 return EL;
5866
5867 // Try again, but use SCEV predicates this time.
5868 return computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit,
5869 /*AllowPredicates=*/true);
5870 }
5871
5872 // Check for a constant condition. These are normally stripped out by
5873 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
5874 // preserve the CFG and is temporarily leaving constant conditions
5875 // in place.
5876 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
5877 if (L->contains(FBB) == !CI->getZExtValue())
5878 // The backedge is always taken.
5879 return getCouldNotCompute();
5880 else
5881 // The backedge is never taken.
5882 return getZero(CI->getType());
5883 }
5884
5885 // If it's not an integer or pointer comparison then compute it the hard way.
5886 return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
5887}
5888
5889ScalarEvolution::ExitLimit
5890ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
5891 ICmpInst *ExitCond,
5892 BasicBlock *TBB,
5893 BasicBlock *FBB,
5894 bool ControlsExit,
5895 bool AllowPredicates) {
5896
5897 // If the condition was exit on true, convert the condition to exit on false
5898 ICmpInst::Predicate Cond;
5899 if (!L->contains(FBB))
5900 Cond = ExitCond->getPredicate();
5901 else
5902 Cond = ExitCond->getInversePredicate();
5903
5904 // Handle common loops like: for (X = "string"; *X; ++X)
5905 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
5906 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
5907 ExitLimit ItCnt =
5908 computeLoadConstantCompareExitLimit(LI, RHS, L, Cond);
5909 if (ItCnt.hasAnyInfo())
5910 return ItCnt;
5911 }
5912
5913 ExitLimit ShiftEL = computeShiftCompareExitLimit(
5914 ExitCond->getOperand(0), ExitCond->getOperand(1), L, Cond);
5915 if (ShiftEL.hasAnyInfo())
5916 return ShiftEL;
5917
5918 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
5919 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
5920
5921 // Try to evaluate any dependencies out of the loop.
5922 LHS = getSCEVAtScope(LHS, L);
5923 RHS = getSCEVAtScope(RHS, L);
5924
5925 // At this point, we would like to compute how many iterations of the
5926 // loop the predicate will return true for these inputs.
5927 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
5928 // If there is a loop-invariant, force it into the RHS.
5929 std::swap(LHS, RHS);
5930 Cond = ICmpInst::getSwappedPredicate(Cond);
5931 }
5932
5933 // Simplify the operands before analyzing them.
5934 (void)SimplifyICmpOperands(Cond, LHS, RHS);
5935
5936 // If we have a comparison of a chrec against a constant, try to use value
5937 // ranges to answer this query.
5938 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
5939 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
5940 if (AddRec->getLoop() == L) {
5941 // Form the constant range.
5942 ConstantRange CompRange(
5943 ICmpInst::makeConstantRange(Cond, RHSC->getAPInt()));
5944
5945 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
5946 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
5947 }
5948
5949 switch (Cond) {
5950 case ICmpInst::ICMP_NE: { // while (X != Y)
5951 // Convert to: while (X-Y != 0)
5952 ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
5953 AllowPredicates);
5954 if (EL.hasAnyInfo()) return EL;
5955 break;
5956 }
5957 case ICmpInst::ICMP_EQ: { // while (X == Y)
5958 // Convert to: while (X-Y == 0)
5959 ExitLimit EL = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
5960 if (EL.hasAnyInfo()) return EL;
5961 break;
5962 }
5963 case ICmpInst::ICMP_SLT:
5964 case ICmpInst::ICMP_ULT: { // while (X < Y)
5965 bool IsSigned = Cond == ICmpInst::ICMP_SLT;
5966 ExitLimit EL = HowManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
5967 AllowPredicates);
5968 if (EL.hasAnyInfo()) return EL;
5969 break;
5970 }
5971 case ICmpInst::ICMP_SGT:
5972 case ICmpInst::ICMP_UGT: { // while (X > Y)
5973 bool IsSigned = Cond == ICmpInst::ICMP_SGT;
5974 ExitLimit EL =
5975 HowManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
5976 AllowPredicates);
5977 if (EL.hasAnyInfo()) return EL;
5978 break;
5979 }
5980 default:
5981 break;
5982 }
5983 return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
5984}
5985
5986ScalarEvolution::ExitLimit
5987ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
5988 SwitchInst *Switch,
5989 BasicBlock *ExitingBlock,
5990 bool ControlsExit) {
5991 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5991, __PRETTY_FUNCTION__))
;
5992
5993 // Give up if the exit is the default dest of a switch.
5994 if (Switch->getDefaultDest() == ExitingBlock)
5995 return getCouldNotCompute();
5996
5997 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5998, __PRETTY_FUNCTION__))
5998 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 5998, __PRETTY_FUNCTION__))
;
5999 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
6000 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
6001
6002 // while (X != Y) --> while (X-Y != 0)
6003 ExitLimit EL = HowFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
6004 if (EL.hasAnyInfo())
6005 return EL;
6006
6007 return getCouldNotCompute();
6008}
6009
6010static ConstantInt *
6011EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
6012 ScalarEvolution &SE) {
6013 const SCEV *InVal = SE.getConstant(C);
6014 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
6015 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6016, __PRETTY_FUNCTION__))
6016 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6016, __PRETTY_FUNCTION__))
;
6017 return cast<SCEVConstant>(Val)->getValue();
6018}
6019
6020/// computeLoadConstantCompareExitLimit - Given an exit condition of
6021/// 'icmp op load X, cst', try to see if we can compute the backedge
6022/// execution count.
6023ScalarEvolution::ExitLimit
6024ScalarEvolution::computeLoadConstantCompareExitLimit(
6025 LoadInst *LI,
6026 Constant *RHS,
6027 const Loop *L,
6028 ICmpInst::Predicate predicate) {
6029
6030 if (LI->isVolatile()) return getCouldNotCompute();
6031
6032 // Check to see if the loaded pointer is a getelementptr of a global.
6033 // TODO: Use SCEV instead of manually grubbing with GEPs.
6034 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
6035 if (!GEP) return getCouldNotCompute();
6036
6037 // Make sure that it is really a constant global we are gepping, with an
6038 // initializer, and make sure the first IDX is really 0.
6039 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
6040 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
6041 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
6042 !cast<Constant>(GEP->getOperand(1))->isNullValue())
6043 return getCouldNotCompute();
6044
6045 // Okay, we allow one non-constant index into the GEP instruction.
6046 Value *VarIdx = nullptr;
6047 std::vector<Constant*> Indexes;
6048 unsigned VarIdxNum = 0;
6049 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
6050 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
6051 Indexes.push_back(CI);
6052 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
6053 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
6054 VarIdx = GEP->getOperand(i);
6055 VarIdxNum = i-2;
6056 Indexes.push_back(nullptr);
6057 }
6058
6059 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
6060 if (!VarIdx)
6061 return getCouldNotCompute();
6062
6063 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
6064 // Check to see if X is a loop variant variable value now.
6065 const SCEV *Idx = getSCEV(VarIdx);
6066 Idx = getSCEVAtScope(Idx, L);
6067
6068 // We can only recognize very limited forms of loop index expressions, in
6069 // particular, only affine AddRec's like {C1,+,C2}.
6070 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
6071 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
6072 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
6073 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
6074 return getCouldNotCompute();
6075
6076 unsigned MaxSteps = MaxBruteForceIterations;
6077 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
6078 ConstantInt *ItCst = ConstantInt::get(
6079 cast<IntegerType>(IdxExpr->getType()), IterationNum);
6080 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
6081
6082 // Form the GEP offset.
6083 Indexes[VarIdxNum] = Val;
6084
6085 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
6086 Indexes);
6087 if (!Result) break; // Cannot compute!
6088
6089 // Evaluate the condition for this iteration.
6090 Result = ConstantExpr::getICmp(predicate, Result, RHS);
6091 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
6092 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
6093 ++NumArrayLenItCounts;
6094 return getConstant(ItCst); // Found terminating iteration!
6095 }
6096 }
6097 return getCouldNotCompute();
6098}
6099
6100ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
6101 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
6102 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
6103 if (!RHS)
6104 return getCouldNotCompute();
6105
6106 const BasicBlock *Latch = L->getLoopLatch();
6107 if (!Latch)
6108 return getCouldNotCompute();
6109
6110 const BasicBlock *Predecessor = L->getLoopPredecessor();
6111 if (!Predecessor)
6112 return getCouldNotCompute();
6113
6114 // Return true if V is of the form "LHS `shift_op` <positive constant>".
6115 // Return LHS in OutLHS and shift_opt in OutOpCode.
6116 auto MatchPositiveShift =
6117 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
6118
6119 using namespace PatternMatch;
6120
6121 ConstantInt *ShiftAmt;
6122 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6123 OutOpCode = Instruction::LShr;
6124 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6125 OutOpCode = Instruction::AShr;
6126 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
6127 OutOpCode = Instruction::Shl;
6128 else
6129 return false;
6130
6131 return ShiftAmt->getValue().isStrictlyPositive();
6132 };
6133
6134 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
6135 //
6136 // loop:
6137 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
6138 // %iv.shifted = lshr i32 %iv, <positive constant>
6139 //
6140 // Return true on a succesful match. Return the corresponding PHI node (%iv
6141 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
6142 auto MatchShiftRecurrence =
6143 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
6144 Optional<Instruction::BinaryOps> PostShiftOpCode;
6145
6146 {
6147 Instruction::BinaryOps OpC;
6148 Value *V;
6149
6150 // If we encounter a shift instruction, "peel off" the shift operation,
6151 // and remember that we did so. Later when we inspect %iv's backedge
6152 // value, we will make sure that the backedge value uses the same
6153 // operation.
6154 //
6155 // Note: the peeled shift operation does not have to be the same
6156 // instruction as the one feeding into the PHI's backedge value. We only
6157 // really care about it being the same *kind* of shift instruction --
6158 // that's all that is required for our later inferences to hold.
6159 if (MatchPositiveShift(LHS, V, OpC)) {
6160 PostShiftOpCode = OpC;
6161 LHS = V;
6162 }
6163 }
6164
6165 PNOut = dyn_cast<PHINode>(LHS);
6166 if (!PNOut || PNOut->getParent() != L->getHeader())
6167 return false;
6168
6169 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
6170 Value *OpLHS;
6171
6172 return
6173 // The backedge value for the PHI node must be a shift by a positive
6174 // amount
6175 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
6176
6177 // of the PHI node itself
6178 OpLHS == PNOut &&
6179
6180 // and the kind of shift should be match the kind of shift we peeled
6181 // off, if any.
6182 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
6183 };
6184
6185 PHINode *PN;
6186 Instruction::BinaryOps OpCode;
6187 if (!MatchShiftRecurrence(LHS, PN, OpCode))
6188 return getCouldNotCompute();
6189
6190 const DataLayout &DL = getDataLayout();
6191
6192 // The key rationale for this optimization is that for some kinds of shift
6193 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
6194 // within a finite number of iterations. If the condition guarding the
6195 // backedge (in the sense that the backedge is taken if the condition is true)
6196 // is false for the value the shift recurrence stabilizes to, then we know
6197 // that the backedge is taken only a finite number of times.
6198
6199 ConstantInt *StableValue = nullptr;
6200 switch (OpCode) {
6201 default:
6202 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6202)
;
6203
6204 case Instruction::AShr: {
6205 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
6206 // bitwidth(K) iterations.
6207 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
6208 bool KnownZero, KnownOne;
6209 ComputeSignBit(FirstValue, KnownZero, KnownOne, DL, 0, nullptr,
6210 Predecessor->getTerminator(), &DT);
6211 auto *Ty = cast<IntegerType>(RHS->getType());
6212 if (KnownZero)
6213 StableValue = ConstantInt::get(Ty, 0);
6214 else if (KnownOne)
6215 StableValue = ConstantInt::get(Ty, -1, true);
6216 else
6217 return getCouldNotCompute();
6218
6219 break;
6220 }
6221 case Instruction::LShr:
6222 case Instruction::Shl:
6223 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
6224 // stabilize to 0 in at most bitwidth(K) iterations.
6225 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
6226 break;
6227 }
6228
6229 auto *Result =
6230 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
6231 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6232, __PRETTY_FUNCTION__))
6232 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6232, __PRETTY_FUNCTION__))
;
6233
6234 if (Result->isZeroValue()) {
6235 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
6236 const SCEV *UpperBound =
6237 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
6238 SCEVUnionPredicate P;
6239 return ExitLimit(getCouldNotCompute(), UpperBound, P);
6240 }
6241
6242 return getCouldNotCompute();
6243}
6244
6245/// CanConstantFold - Return true if we can constant fold an instruction of the
6246/// specified type, assuming that all operands were constants.
6247static bool CanConstantFold(const Instruction *I) {
6248 if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
6249 isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
6250 isa<LoadInst>(I))
6251 return true;
6252
6253 if (const CallInst *CI = dyn_cast<CallInst>(I))
6254 if (const Function *F = CI->getCalledFunction())
6255 return canConstantFoldCallTo(F);
6256 return false;
6257}
6258
6259/// Determine whether this instruction can constant evolve within this loop
6260/// assuming its operands can all constant evolve.
6261static bool canConstantEvolve(Instruction *I, const Loop *L) {
6262 // An instruction outside of the loop can't be derived from a loop PHI.
6263 if (!L->contains(I)) return false;
6264
6265 if (isa<PHINode>(I)) {
6266 // We don't currently keep track of the control flow needed to evaluate
6267 // PHIs, so we cannot handle PHIs inside of loops.
6268 return L->getHeader() == I->getParent();
6269 }
6270
6271 // If we won't be able to constant fold this expression even if the operands
6272 // are constants, bail early.
6273 return CanConstantFold(I);
6274}
6275
6276/// getConstantEvolvingPHIOperands - Implement getConstantEvolvingPHI by
6277/// recursing through each instruction operand until reaching a loop header phi.
6278static PHINode *
6279getConstantEvolvingPHIOperands(Instruction *UseInst, const Loop *L,
6280 DenseMap<Instruction *, PHINode *> &PHIMap) {
6281
6282 // Otherwise, we can evaluate this instruction if all of its operands are
6283 // constant or derived from a PHI node themselves.
6284 PHINode *PHI = nullptr;
6285 for (Value *Op : UseInst->operands()) {
6286 if (isa<Constant>(Op)) continue;
6287
6288 Instruction *OpInst = dyn_cast<Instruction>(Op);
6289 if (!OpInst || !canConstantEvolve(OpInst, L)) return nullptr;
6290
6291 PHINode *P = dyn_cast<PHINode>(OpInst);
6292 if (!P)
6293 // If this operand is already visited, reuse the prior result.
6294 // We may have P != PHI if this is the deepest point at which the
6295 // inconsistent paths meet.
6296 P = PHIMap.lookup(OpInst);
6297 if (!P) {
6298 // Recurse and memoize the results, whether a phi is found or not.
6299 // This recursive call invalidates pointers into PHIMap.
6300 P = getConstantEvolvingPHIOperands(OpInst, L, PHIMap);
6301 PHIMap[OpInst] = P;
6302 }
6303 if (!P)
6304 return nullptr; // Not evolving from PHI
6305 if (PHI && PHI != P)
6306 return nullptr; // Evolving from multiple different PHIs.
6307 PHI = P;
6308 }
6309 // This is a expression evolving from a constant PHI!
6310 return PHI;
6311}
6312
6313/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
6314/// in the loop that V is derived from. We allow arbitrary operations along the
6315/// way, but the operands of an operation must either be constants or a value
6316/// derived from a constant PHI. If this expression does not fit with these
6317/// constraints, return null.
6318static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
6319 Instruction *I = dyn_cast<Instruction>(V);
6320 if (!I || !canConstantEvolve(I, L)) return nullptr;
6321
6322 if (PHINode *PN = dyn_cast<PHINode>(I))
6323 return PN;
6324
6325 // Record non-constant instructions contained by the loop.
6326 DenseMap<Instruction *, PHINode *> PHIMap;
6327 return getConstantEvolvingPHIOperands(I, L, PHIMap);
6328}
6329
6330/// EvaluateExpression - Given an expression that passes the
6331/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
6332/// in the loop has the value PHIVal. If we can't fold this expression for some
6333/// reason, return null.
6334static Constant *EvaluateExpression(Value *V, const Loop *L,
6335 DenseMap<Instruction *, Constant *> &Vals,
6336 const DataLayout &DL,
6337 const TargetLibraryInfo *TLI) {
6338 // Convenient constant check, but redundant for recursive calls.
6339 if (Constant *C = dyn_cast<Constant>(V)) return C;
6340 Instruction *I = dyn_cast<Instruction>(V);
6341 if (!I) return nullptr;
6342
6343 if (Constant *C = Vals.lookup(I)) return C;
6344
6345 // An instruction inside the loop depends on a value outside the loop that we
6346 // weren't given a mapping for, or a value such as a call inside the loop.
6347 if (!canConstantEvolve(I, L)) return nullptr;
6348
6349 // An unmapped PHI can be due to a branch or another loop inside this loop,
6350 // or due to this not being the initial iteration through a loop where we
6351 // couldn't compute the evolution of this particular PHI last time.
6352 if (isa<PHINode>(I)) return nullptr;
6353
6354 std::vector<Constant*> Operands(I->getNumOperands());
6355
6356 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
6357 Instruction *Operand = dyn_cast<Instruction>(I->getOperand(i));
6358 if (!Operand) {
6359 Operands[i] = dyn_cast<Constant>(I->getOperand(i));
6360 if (!Operands[i]) return nullptr;
6361 continue;
6362 }
6363 Constant *C = EvaluateExpression(Operand, L, Vals, DL, TLI);
6364 Vals[Operand] = C;
6365 if (!C) return nullptr;
6366 Operands[i] = C;
6367 }
6368
6369 if (CmpInst *CI = dyn_cast<CmpInst>(I))
6370 return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
6371 Operands[1], DL, TLI);
6372 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
6373 if (!LI->isVolatile())
6374 return ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
6375 }
6376 return ConstantFoldInstOperands(I, Operands, DL, TLI);
6377}
6378
6379
6380// If every incoming value to PN except the one for BB is a specific Constant,
6381// return that, else return nullptr.
6382static Constant *getOtherIncomingValue(PHINode *PN, BasicBlock *BB) {
6383 Constant *IncomingVal = nullptr;
6384
6385 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
6386 if (PN->getIncomingBlock(i) == BB)
6387 continue;
6388
6389 auto *CurrentVal = dyn_cast<Constant>(PN->getIncomingValue(i));
6390 if (!CurrentVal)
6391 return nullptr;
6392
6393 if (IncomingVal != CurrentVal) {
6394 if (IncomingVal)
6395 return nullptr;
6396 IncomingVal = CurrentVal;
6397 }
6398 }
6399
6400 return IncomingVal;
6401}
6402
6403/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
6404/// in the header of its containing loop, we know the loop executes a
6405/// constant number of times, and the PHI node is just a recurrence
6406/// involving constants, fold it.
6407Constant *
6408ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
6409 const APInt &BEs,
6410 const Loop *L) {
6411 auto I = ConstantEvolutionLoopExitValue.find(PN);
6412 if (I != ConstantEvolutionLoopExitValue.end())
6413 return I->second;
6414
6415 if (BEs.ugt(MaxBruteForceIterations))
6416 return ConstantEvolutionLoopExitValue[PN] = nullptr; // Not going to evaluate it.
6417
6418 Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
6419
6420 DenseMap<Instruction *, Constant *> CurrentIterVals;
6421 BasicBlock *Header = L->getHeader();
6422 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6422, __PRETTY_FUNCTION__))
;
6423
6424 BasicBlock *Latch = L->getLoopLatch();
6425 if (!Latch)
6426 return nullptr;
6427
6428 for (auto &I : *Header) {
6429 PHINode *PHI = dyn_cast<PHINode>(&I);
6430 if (!PHI) break;
6431 auto *StartCST = getOtherIncomingValue(PHI, Latch);
6432 if (!StartCST) continue;
6433 CurrentIterVals[PHI] = StartCST;
6434 }
6435 if (!CurrentIterVals.count(PN))
6436 return RetVal = nullptr;
6437
6438 Value *BEValue = PN->getIncomingValueForBlock(Latch);
6439
6440 // Execute the loop symbolically to determine the exit value.
6441 if (BEs.getActiveBits() >= 32)
6442 return RetVal = nullptr; // More than 2^32-1 iterations?? Not doing it!
6443
6444 unsigned NumIterations = BEs.getZExtValue(); // must be in range
6445 unsigned IterationNum = 0;
6446 const DataLayout &DL = getDataLayout();
6447 for (; ; ++IterationNum) {
6448 if (IterationNum == NumIterations)
6449 return RetVal = CurrentIterVals[PN]; // Got exit value!
6450
6451 // Compute the value of the PHIs for the next iteration.
6452 // EvaluateExpression adds non-phi values to the CurrentIterVals map.
6453 DenseMap<Instruction *, Constant *> NextIterVals;
6454 Constant *NextPHI =
6455 EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
6456 if (!NextPHI)
6457 return nullptr; // Couldn't evaluate!
6458 NextIterVals[PN] = NextPHI;
6459
6460 bool StoppedEvolving = NextPHI == CurrentIterVals[PN];
6461
6462 // Also evaluate the other PHI nodes. However, we don't get to stop if we
6463 // cease to be able to evaluate one of them or if they stop evolving,
6464 // because that doesn't necessarily prevent us from computing PN.
6465 SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
6466 for (const auto &I : CurrentIterVals) {
6467 PHINode *PHI = dyn_cast<PHINode>(I.first);
6468 if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
6469 PHIsToCompute.emplace_back(PHI, I.second);
6470 }
6471 // We use two distinct loops because EvaluateExpression may invalidate any
6472 // iterators into CurrentIterVals.
6473 for (const auto &I : PHIsToCompute) {
6474 PHINode *PHI = I.first;
6475 Constant *&NextPHI = NextIterVals[PHI];
6476 if (!NextPHI) { // Not already computed.
6477 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
6478 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
6479 }
6480 if (NextPHI != I.second)
6481 StoppedEvolving = false;
6482 }
6483
6484 // If all entries in CurrentIterVals == NextIterVals then we can stop
6485 // iterating, the loop can't continue to change.
6486 if (StoppedEvolving)
6487 return RetVal = CurrentIterVals[PN];
6488
6489 CurrentIterVals.swap(NextIterVals);
6490 }
6491}
6492
6493const SCEV *ScalarEvolution::computeExitCountExhaustively(const Loop *L,
6494 Value *Cond,
6495 bool ExitWhen) {
6496 PHINode *PN = getConstantEvolvingPHI(Cond, L);
6497 if (!PN) return getCouldNotCompute();
6498
6499 // If the loop is canonicalized, the PHI will have exactly two entries.
6500 // That's the only form we support here.
6501 if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
6502
6503 DenseMap<Instruction *, Constant *> CurrentIterVals;
6504 BasicBlock *Header = L->getHeader();
6505 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6505, __PRETTY_FUNCTION__))
;
6506
6507 BasicBlock *Latch = L->getLoopLatch();
6508 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6508, __PRETTY_FUNCTION__))
;
6509
6510 for (auto &I : *Header) {
6511 PHINode *PHI = dyn_cast<PHINode>(&I);
6512 if (!PHI)
6513 break;
6514 auto *StartCST = getOtherIncomingValue(PHI, Latch);
6515 if (!StartCST) continue;
6516 CurrentIterVals[PHI] = StartCST;
6517 }
6518 if (!CurrentIterVals.count(PN))
6519 return getCouldNotCompute();
6520
6521 // Okay, we find a PHI node that defines the trip count of this loop. Execute
6522 // the loop symbolically to determine when the condition gets a value of
6523 // "ExitWhen".
6524 unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
6525 const DataLayout &DL = getDataLayout();
6526 for (unsigned IterationNum = 0; IterationNum != MaxIterations;++IterationNum){
6527 auto *CondVal = dyn_cast_or_null<ConstantInt>(
6528 EvaluateExpression(Cond, L, CurrentIterVals, DL, &TLI));
6529
6530 // Couldn't symbolically evaluate.
6531 if (!CondVal) return getCouldNotCompute();
6532
6533 if (CondVal->getValue() == uint64_t(ExitWhen)) {
6534 ++NumBruteForceTripCountsComputed;
6535 return getConstant(Type::getInt32Ty(getContext()), IterationNum);
6536 }
6537
6538 // Update all the PHI nodes for the next iteration.
6539 DenseMap<Instruction *, Constant *> NextIterVals;
6540
6541 // Create a list of which PHIs we need to compute. We want to do this before
6542 // calling EvaluateExpression on them because that may invalidate iterators
6543 // into CurrentIterVals.
6544 SmallVector<PHINode *, 8> PHIsToCompute;
6545 for (const auto &I : CurrentIterVals) {
6546 PHINode *PHI = dyn_cast<PHINode>(I.first);
6547 if (!PHI || PHI->getParent() != Header) continue;
6548 PHIsToCompute.push_back(PHI);
6549 }
6550 for (PHINode *PHI : PHIsToCompute) {
6551 Constant *&NextPHI = NextIterVals[PHI];
6552 if (NextPHI) continue; // Already computed!
6553
6554 Value *BEValue = PHI->getIncomingValueForBlock(Latch);
6555 NextPHI = EvaluateExpression(BEValue, L, CurrentIterVals, DL, &TLI);
6556 }
6557 CurrentIterVals.swap(NextIterVals);
6558 }
6559
6560 // Too many iterations were needed to evaluate.
6561 return getCouldNotCompute();
6562}
6563
6564/// getSCEVAtScope - Return a SCEV expression for the specified value
6565/// at the specified scope in the program. The L value specifies a loop
6566/// nest to evaluate the expression at, where null is the top-level or a
6567/// specified loop is immediately inside of the loop.
6568///
6569/// This method can be used to compute the exit value for a variable defined
6570/// in a loop by querying what the value will hold in the parent loop.
6571///
6572/// In the case that a relevant loop exit value cannot be computed, the
6573/// original value V is returned.
6574const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
6575 SmallVector<std::pair<const Loop *, const SCEV *>, 2> &Values =
6576 ValuesAtScopes[V];
6577 // Check to see if we've folded this expression at this loop before.
6578 for (auto &LS : Values)
6579 if (LS.first == L)
6580 return LS.second ? LS.second : V;
6581
6582 Values.emplace_back(L, nullptr);
6583
6584 // Otherwise compute it.
6585 const SCEV *C = computeSCEVAtScope(V, L);
6586 for (auto &LS : reverse(ValuesAtScopes[V]))
6587 if (LS.first == L) {
6588 LS.second = C;
6589 break;
6590 }
6591 return C;
6592}
6593
6594/// This builds up a Constant using the ConstantExpr interface. That way, we
6595/// will return Constants for objects which aren't represented by a
6596/// SCEVConstant, because SCEVConstant is restricted to ConstantInt.
6597/// Returns NULL if the SCEV isn't representable as a Constant.
6598static Constant *BuildConstantFromSCEV(const SCEV *V) {
6599 switch (static_cast<SCEVTypes>(V->getSCEVType())) {
6600 case scCouldNotCompute:
6601 case scAddRecExpr:
6602 break;
6603 case scConstant:
6604 return cast<SCEVConstant>(V)->getValue();
6605 case scUnknown:
6606 return dyn_cast<Constant>(cast<SCEVUnknown>(V)->getValue());
6607 case scSignExtend: {
6608 const SCEVSignExtendExpr *SS = cast<SCEVSignExtendExpr>(V);
6609 if (Constant *CastOp = BuildConstantFromSCEV(SS->getOperand()))
6610 return ConstantExpr::getSExt(CastOp, SS->getType());
6611 break;
6612 }
6613 case scZeroExtend: {
6614 const SCEVZeroExtendExpr *SZ = cast<SCEVZeroExtendExpr>(V);
6615 if (Constant *CastOp = BuildConstantFromSCEV(SZ->getOperand()))
6616 return ConstantExpr::getZExt(CastOp, SZ->getType());
6617 break;
6618 }
6619 case scTruncate: {
6620 const SCEVTruncateExpr *ST = cast<SCEVTruncateExpr>(V);
6621 if (Constant *CastOp = BuildConstantFromSCEV(ST->getOperand()))
6622 return ConstantExpr::getTrunc(CastOp, ST->getType());
6623 break;
6624 }
6625 case scAddExpr: {
6626 const SCEVAddExpr *SA = cast<SCEVAddExpr>(V);
6627 if (Constant *C = BuildConstantFromSCEV(SA->getOperand(0))) {
6628 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
6629 unsigned AS = PTy->getAddressSpace();
6630 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
6631 C = ConstantExpr::getBitCast(C, DestPtrTy);
6632 }
6633 for (unsigned i = 1, e = SA->getNumOperands(); i != e; ++i) {
6634 Constant *C2 = BuildConstantFromSCEV(SA->getOperand(i));
6635 if (!C2) return nullptr;
6636
6637 // First pointer!
6638 if (!C->getType()->isPointerTy() && C2->getType()->isPointerTy()) {
6639 unsigned AS = C2->getType()->getPointerAddressSpace();
6640 std::swap(C, C2);
6641 Type *DestPtrTy = Type::getInt8PtrTy(C->getContext(), AS);
6642 // The offsets have been converted to bytes. We can add bytes to an
6643 // i8* by GEP with the byte count in the first index.
6644 C = ConstantExpr::getBitCast(C, DestPtrTy);
6645 }
6646
6647 // Don't bother trying to sum two pointers. We probably can't
6648 // statically compute a load that results from it anyway.
6649 if (C2->getType()->isPointerTy())
6650 return nullptr;
6651
6652 if (PointerType *PTy = dyn_cast<PointerType>(C->getType())) {
6653 if (PTy->getElementType()->isStructTy())
6654 C2 = ConstantExpr::getIntegerCast(
6655 C2, Type::getInt32Ty(C->getContext()), true);
6656 C = ConstantExpr::getGetElementPtr(PTy->getElementType(), C, C2);
6657 } else
6658 C = ConstantExpr::getAdd(C, C2);
6659 }
6660 return C;
6661 }
6662 break;
6663 }
6664 case scMulExpr: {
6665 const SCEVMulExpr *SM = cast<SCEVMulExpr>(V);
6666 if (Constant *C = BuildConstantFromSCEV(SM->getOperand(0))) {
6667 // Don't bother with pointers at all.
6668 if (C->getType()->isPointerTy()) return nullptr;
6669 for (unsigned i = 1, e = SM->getNumOperands(); i != e; ++i) {
6670 Constant *C2 = BuildConstantFromSCEV(SM->getOperand(i));
6671 if (!C2 || C2->getType()->isPointerTy()) return nullptr;
6672 C = ConstantExpr::getMul(C, C2);
6673 }
6674 return C;
6675 }
6676 break;
6677 }
6678 case scUDivExpr: {
6679 const SCEVUDivExpr *SU = cast<SCEVUDivExpr>(V);
6680 if (Constant *LHS = BuildConstantFromSCEV(SU->getLHS()))
6681 if (Constant *RHS = BuildConstantFromSCEV(SU->getRHS()))
6682 if (LHS->getType() == RHS->getType())
6683 return ConstantExpr::getUDiv(LHS, RHS);
6684 break;
6685 }
6686 case scSMaxExpr:
6687 case scUMaxExpr:
6688 break; // TODO: smax, umax.
6689 }
6690 return nullptr;
6691}
6692
6693const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
6694 if (isa<SCEVConstant>(V)) return V;
6695
6696 // If this instruction is evolved from a constant-evolving PHI, compute the
6697 // exit value from the loop without using SCEVs.
6698 if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
6699 if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
6700 const Loop *LI = this->LI[I->getParent()];
6701 if (LI && LI->getParentLoop() == L) // Looking for loop exit value.
6702 if (PHINode *PN = dyn_cast<PHINode>(I))
6703 if (PN->getParent() == LI->getHeader()) {
6704 // Okay, there is no closed form solution for the PHI node. Check
6705 // to see if the loop that contains it has a known backedge-taken
6706 // count. If so, we may be able to force computation of the exit
6707 // value.
6708 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI);
6709 if (const SCEVConstant *BTCC =
6710 dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
6711 // Okay, we know how many times the containing loop executes. If
6712 // this is a constant evolving PHI node, get the final value at
6713 // the specified iteration number.
6714 Constant *RV =
6715 getConstantEvolutionLoopExitValue(PN, BTCC->getAPInt(), LI);
6716 if (RV) return getSCEV(RV);
6717 }
6718 }
6719
6720 // Okay, this is an expression that we cannot symbolically evaluate
6721 // into a SCEV. Check to see if it's possible to symbolically evaluate
6722 // the arguments into constants, and if so, try to constant propagate the
6723 // result. This is particularly useful for computing loop exit values.
6724 if (CanConstantFold(I)) {
6725 SmallVector<Constant *, 4> Operands;
6726 bool MadeImprovement = false;
6727 for (Value *Op : I->operands()) {
6728 if (Constant *C = dyn_cast<Constant>(Op)) {
6729 Operands.push_back(C);
6730 continue;
6731 }
6732
6733 // If any of the operands is non-constant and if they are
6734 // non-integer and non-pointer, don't even try to analyze them
6735 // with scev techniques.
6736 if (!isSCEVable(Op->getType()))
6737 return V;
6738
6739 const SCEV *OrigV = getSCEV(Op);
6740 const SCEV *OpV = getSCEVAtScope(OrigV, L);
6741 MadeImprovement |= OrigV != OpV;
6742
6743 Constant *C = BuildConstantFromSCEV(OpV);
6744 if (!C) return V;
6745 if (C->getType() != Op->getType())
6746 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
6747 Op->getType(),
6748 false),
6749 C, Op->getType());
6750 Operands.push_back(C);
6751 }
6752
6753 // Check to see if getSCEVAtScope actually made an improvement.
6754 if (MadeImprovement) {
6755 Constant *C = nullptr;
6756 const DataLayout &DL = getDataLayout();
6757 if (const CmpInst *CI = dyn_cast<CmpInst>(I))
6758 C = ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
6759 Operands[1], DL, &TLI);
6760 else if (const LoadInst *LI = dyn_cast<LoadInst>(I)) {
6761 if (!LI->isVolatile())
6762 C = ConstantFoldLoadFromConstPtr(Operands[0], LI->getType(), DL);
6763 } else
6764 C = ConstantFoldInstOperands(I, Operands, DL, &TLI);
6765 if (!C) return V;
6766 return getSCEV(C);
6767 }
6768 }
6769 }
6770
6771 // This is some other type of SCEVUnknown, just return it.
6772 return V;
6773 }
6774
6775 if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
6776 // Avoid performing the look-up in the common case where the specified
6777 // expression has no loop-variant portions.
6778 for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
6779 const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
6780 if (OpAtScope != Comm->getOperand(i)) {
6781 // Okay, at least one of these operands is loop variant but might be
6782 // foldable. Build a new instance of the folded commutative expression.
6783 SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
6784 Comm->op_begin()+i);
6785 NewOps.push_back(OpAtScope);
6786
6787 for (++i; i != e; ++i) {
6788 OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
6789 NewOps.push_back(OpAtScope);
6790 }
6791 if (isa<SCEVAddExpr>(Comm))
6792 return getAddExpr(NewOps);
6793 if (isa<SCEVMulExpr>(Comm))
6794 return getMulExpr(NewOps);
6795 if (isa<SCEVSMaxExpr>(Comm))
6796 return getSMaxExpr(NewOps);
6797 if (isa<SCEVUMaxExpr>(Comm))
6798 return getUMaxExpr(NewOps);
6799 llvm_unreachable("Unknown commutative SCEV type!")::llvm::llvm_unreachable_internal("Unknown commutative SCEV type!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6799)
;
6800 }
6801 }
6802 // If we got here, all operands are loop invariant.
6803 return Comm;
6804 }
6805
6806 if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
6807 const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
6808 const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
6809 if (LHS == Div->getLHS() && RHS == Div->getRHS())
6810 return Div; // must be loop invariant
6811 return getUDivExpr(LHS, RHS);
6812 }
6813
6814 // If this is a loop recurrence for a loop that does not contain L, then we
6815 // are dealing with the final value computed by the loop.
6816 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
6817 // First, attempt to evaluate each operand.
6818 // Avoid performing the look-up in the common case where the specified
6819 // expression has no loop-variant portions.
6820 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
6821 const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
6822 if (OpAtScope == AddRec->getOperand(i))
6823 continue;
6824
6825 // Okay, at least one of these operands is loop variant but might be
6826 // foldable. Build a new instance of the folded commutative expression.
6827 SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
6828 AddRec->op_begin()+i);
6829 NewOps.push_back(OpAtScope);
6830 for (++i; i != e; ++i)
6831 NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
6832
6833 const SCEV *FoldedRec =
6834 getAddRecExpr(NewOps, AddRec->getLoop(),
6835 AddRec->getNoWrapFlags(SCEV::FlagNW));
6836 AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
6837 // The addrec may be folded to a nonrecurrence, for example, if the
6838 // induction variable is multiplied by zero after constant folding. Go
6839 // ahead and return the folded value.
6840 if (!AddRec)
6841 return FoldedRec;
6842 break;
6843 }
6844
6845 // If the scope is outside the addrec's loop, evaluate it by using the
6846 // loop exit value of the addrec.
6847 if (!AddRec->getLoop()->contains(L)) {
6848 // To evaluate this recurrence, we need to know how many times the AddRec
6849 // loop iterates. Compute this now.
6850 const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
6851 if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
6852
6853 // Then, evaluate the AddRec.
6854 return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
6855 }
6856
6857 return AddRec;
6858 }
6859
6860 if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) {
6861 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
6862 if (Op == Cast->getOperand())
6863 return Cast; // must be loop invariant
6864 return getZeroExtendExpr(Op, Cast->getType());
6865 }
6866
6867 if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) {
6868 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
6869 if (Op == Cast->getOperand())
6870 return Cast; // must be loop invariant
6871 return getSignExtendExpr(Op, Cast->getType());
6872 }
6873
6874 if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) {
6875 const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
6876 if (Op == Cast->getOperand())
6877 return Cast; // must be loop invariant
6878 return getTruncateExpr(Op, Cast->getType());
6879 }
6880
6881 llvm_unreachable("Unknown SCEV type!")::llvm::llvm_unreachable_internal("Unknown SCEV type!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6881)
;
6882}
6883
6884/// getSCEVAtScope - This is a convenience function which does
6885/// getSCEVAtScope(getSCEV(V), L).
6886const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
6887 return getSCEVAtScope(getSCEV(V), L);
6888}
6889
6890/// SolveLinEquationWithOverflow - Finds the minimum unsigned root of the
6891/// following equation:
6892///
6893/// A * X = B (mod N)
6894///
6895/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
6896/// A and B isn't important.
6897///
6898/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
6899static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const APInt &B,
6900 ScalarEvolution &SE) {
6901 uint32_t BW = A.getBitWidth();
6902 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6902, __PRETTY_FUNCTION__))
;
6903 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6903, __PRETTY_FUNCTION__))
;
6904
6905 // 1. D = gcd(A, N)
6906 //
6907 // The gcd of A and N may have only one prime factor: 2. The number of
6908 // trailing zeros in A is its multiplicity
6909 uint32_t Mult2 = A.countTrailingZeros();
6910 // D = 2^Mult2
6911
6912 // 2. Check if B is divisible by D.
6913 //
6914 // B is divisible by D if and only if the multiplicity of prime factor 2 for B
6915 // is not less than multiplicity of this prime factor for D.
6916 if (B.countTrailingZeros() < Mult2)
6917 return SE.getCouldNotCompute();
6918
6919 // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
6920 // modulo (N / D).
6921 //
6922 // (N / D) may need BW+1 bits in its representation. Hence, we'll use this
6923 // bit width during computations.
6924 APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
6925 APInt Mod(BW + 1, 0);
6926 Mod.setBit(BW - Mult2); // Mod = N / D
6927 APInt I = AD.multiplicativeInverse(Mod);
6928
6929 // 4. Compute the minimum unsigned root of the equation:
6930 // I * (B / D) mod (N / D)
6931 APInt Result = (I * B.lshr(Mult2).zext(BW + 1)).urem(Mod);
6932
6933 // The result is guaranteed to be less than 2^BW so we may truncate it to BW
6934 // bits.
6935 return SE.getConstant(Result.trunc(BW));
6936}
6937
6938/// SolveQuadraticEquation - Find the roots of the quadratic equation for the
6939/// given quadratic chrec {L,+,M,+,N}. This returns either the two roots (which
6940/// might be the same) or two SCEVCouldNotCompute objects.
6941///
6942static std::pair<const SCEV *,const SCEV *>
6943SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
6944 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 6944, __PRETTY_FUNCTION__))
;
6945 const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
6946 const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
6947 const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
6948
6949 // We currently can only solve this if the coefficients are constants.
6950 if (!LC || !MC || !NC) {
6951 const SCEV *CNC = SE.getCouldNotCompute();
6952 return {CNC, CNC};
6953 }
6954
6955 uint32_t BitWidth = LC->getAPInt().getBitWidth();
6956 const APInt &L = LC->getAPInt();
6957 const APInt &M = MC->getAPInt();
6958 const APInt &N = NC->getAPInt();
6959 APInt Two(BitWidth, 2);
6960 APInt Four(BitWidth, 4);
6961
6962 {
6963 using namespace APIntOps;
6964 const APInt& C = L;
6965 // Convert from chrec coefficients to polynomial coefficients AX^2+BX+C
6966 // The B coefficient is M-N/2
6967 APInt B(M);
6968 B -= sdiv(N,Two);
6969
6970 // The A coefficient is N/2
6971 APInt A(N.sdiv(Two));
6972
6973 // Compute the B^2-4ac term.
6974 APInt SqrtTerm(B);
6975 SqrtTerm *= B;
6976 SqrtTerm -= Four * (A * C);
6977
6978 if (SqrtTerm.isNegative()) {
6979 // The loop is provably infinite.
6980 const SCEV *CNC = SE.getCouldNotCompute();
6981 return {CNC, CNC};
6982 }
6983
6984 // Compute sqrt(B^2-4ac). This is guaranteed to be the nearest
6985 // integer value or else APInt::sqrt() will assert.
6986 APInt SqrtVal(SqrtTerm.sqrt());
6987
6988 // Compute the two solutions for the quadratic formula.
6989 // The divisions must be performed as signed divisions.
6990 APInt NegB(-B);
6991 APInt TwoA(A << 1);
6992 if (TwoA.isMinValue()) {
6993 const SCEV *CNC = SE.getCouldNotCompute();
6994 return {CNC, CNC};
6995 }
6996
6997 LLVMContext &Context = SE.getContext();
6998
6999 ConstantInt *Solution1 =
7000 ConstantInt::get(Context, (NegB + SqrtVal).sdiv(TwoA));
7001 ConstantInt *Solution2 =
7002 ConstantInt::get(Context, (NegB - SqrtVal).sdiv(TwoA));
7003
7004 return {SE.getConstant(Solution1), SE.getConstant(Solution2)};
7005 } // end APIntOps namespace
7006}
7007
7008/// HowFarToZero - Return the number of times a backedge comparing the specified
7009/// value to zero will execute. If not computable, return CouldNotCompute.
7010///
7011/// This is only used for loops with a "x != y" exit test. The exit condition is
7012/// now expressed as a single expression, V = x-y. So the exit test is
7013/// effectively V != 0. We know and take advantage of the fact that this
7014/// expression only being used in a comparison by zero context.
7015ScalarEvolution::ExitLimit
7016ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L, bool ControlsExit,
7017 bool AllowPredicates) {
7018 SCEVUnionPredicate P;
7019 // If the value is a constant
7020 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
7021 // If the value is already zero, the branch will execute zero times.
7022 if (C->getValue()->isZero()) return C;
7023 return getCouldNotCompute(); // Otherwise it will loop infinitely.
7024 }
7025
7026 const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V);
7027 if (!AddRec && AllowPredicates)
7028 // Try to make this an AddRec using runtime tests, in the first X
7029 // iterations of this loop, where X is the SCEV expression found by the
7030 // algorithm below.
7031 AddRec = convertSCEVToAddRecWithPredicates(V, L, P);
7032
7033 if (!AddRec || AddRec->getLoop() != L)
7034 return getCouldNotCompute();
7035
7036 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
7037 // the quadratic equation to solve it.
7038 if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
7039 std::pair<const SCEV *,const SCEV *> Roots =
7040 SolveQuadraticEquation(AddRec, *this);
7041 const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
7042 const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
7043 if (R1 && R2) {
7044 // Pick the smallest positive root value.
7045 if (ConstantInt *CB =
7046 dyn_cast<ConstantInt>(ConstantExpr::getICmp(CmpInst::ICMP_ULT,
7047 R1->getValue(),
7048 R2->getValue()))) {
7049 if (!CB->getZExtValue())
7050 std::swap(R1, R2); // R1 is the minimum root now.
7051
7052 // We can only use this value if the chrec ends up with an exact zero
7053 // value at this index. When solving for "X*X != 5", for example, we
7054 // should not accept a root of 2.
7055 const SCEV *Val = AddRec->evaluateAtIteration(R1, *this);
7056 if (Val->isZero())
7057 return ExitLimit(R1, R1, P); // We found a quadratic root!
7058 }
7059 }
7060 return getCouldNotCompute();
7061 }
7062
7063 // Otherwise we can only handle this if it is affine.
7064 if (!AddRec->isAffine())
7065 return getCouldNotCompute();
7066
7067 // If this is an affine expression, the execution count of this branch is
7068 // the minimum unsigned root of the following equation:
7069 //
7070 // Start + Step*N = 0 (mod 2^BW)
7071 //
7072 // equivalent to:
7073 //
7074 // Step*N = -Start (mod 2^BW)
7075 //
7076 // where BW is the common bit width of Start and Step.
7077
7078 // Get the initial value for the loop.
7079 const SCEV *Start = getSCEVAtScope(AddRec->getStart(), L->getParentLoop());
7080 const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1), L->getParentLoop());
7081
7082 // For now we handle only constant steps.
7083 //
7084 // TODO: Handle a nonconstant Step given AddRec<NUW>. If the
7085 // AddRec is NUW, then (in an unsigned sense) it cannot be counting up to wrap
7086 // to 0, it must be counting down to equal 0. Consequently, N = Start / -Step.
7087 // We have not yet seen any such cases.
7088 const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step);
7089 if (!StepC || StepC->getValue()->equalsInt(0))
7090 return getCouldNotCompute();
7091
7092 // For positive steps (counting up until unsigned overflow):
7093 // N = -Start/Step (as unsigned)
7094 // For negative steps (counting down to zero):
7095 // N = Start/-Step
7096 // First compute the unsigned distance from zero in the direction of Step.
7097 bool CountDown = StepC->getAPInt().isNegative();
7098 const SCEV *Distance = CountDown ? Start : getNegativeSCEV(Start);
7099
7100 // Handle unitary steps, which cannot wraparound.
7101 // 1*N = -Start; -1*N = Start (mod 2^BW), so:
7102 // N = Distance (as unsigned)
7103 if (StepC->getValue()->equalsInt(1) || StepC->getValue()->isAllOnesValue()) {
7104 ConstantRange CR = getUnsignedRange(Start);
7105 const SCEV *MaxBECount;
7106 if (!CountDown && CR.getUnsignedMin().isMinValue())
7107 // When counting up, the worst starting value is 1, not 0.
7108 MaxBECount = CR.getUnsignedMax().isMinValue()
7109 ? getConstant(APInt::getMinValue(CR.getBitWidth()))
7110 : getConstant(APInt::getMaxValue(CR.getBitWidth()));
7111 else
7112 MaxBECount = getConstant(CountDown ? CR.getUnsignedMax()
7113 : -CR.getUnsignedMin());
7114 return ExitLimit(Distance, MaxBECount, P);
7115 }
7116
7117 // As a special case, handle the instance where Step is a positive power of
7118 // two. In this case, determining whether Step divides Distance evenly can be
7119 // done by counting and comparing the number of trailing zeros of Step and
7120 // Distance.
7121 if (!CountDown) {
7122 const APInt &StepV = StepC->getAPInt();
7123 // StepV.isPowerOf2() returns true if StepV is an positive power of two. It
7124 // also returns true if StepV is maximally negative (eg, INT_MIN), but that
7125 // case is not handled as this code is guarded by !CountDown.
7126 if (StepV.isPowerOf2() &&
7127 GetMinTrailingZeros(Distance) >= StepV.countTrailingZeros()) {
7128 // Here we've constrained the equation to be of the form
7129 //
7130 // 2^(N + k) * Distance' = (StepV == 2^N) * X (mod 2^W) ... (0)
7131 //
7132 // where we're operating on a W bit wide integer domain and k is
7133 // non-negative. The smallest unsigned solution for X is the trip count.
7134 //
7135 // (0) is equivalent to:
7136 //
7137 // 2^(N + k) * Distance' - 2^N * X = L * 2^W
7138 // <=> 2^N(2^k * Distance' - X) = L * 2^(W - N) * 2^N
7139 // <=> 2^k * Distance' - X = L * 2^(W - N)
7140 // <=> 2^k * Distance' = L * 2^(W - N) + X ... (1)
7141 //
7142 // The smallest X satisfying (1) is unsigned remainder of dividing the LHS
7143 // by 2^(W - N).
7144 //
7145 // <=> X = 2^k * Distance' URem 2^(W - N) ... (2)
7146 //
7147 // E.g. say we're solving
7148 //
7149 // 2 * Val = 2 * X (in i8) ... (3)
7150 //
7151 // then from (2), we get X = Val URem i8 128 (k = 0 in this case).
7152 //
7153 // Note: It is tempting to solve (3) by setting X = Val, but Val is not
7154 // necessarily the smallest unsigned value of X that satisfies (3).
7155 // E.g. if Val is i8 -127 then the smallest value of X that satisfies (3)
7156 // is i8 1, not i8 -127
7157
7158 const auto *ModuloResult = getUDivExactExpr(Distance, Step);
7159
7160 // Since SCEV does not have a URem node, we construct one using a truncate
7161 // and a zero extend.
7162
7163 unsigned NarrowWidth = StepV.getBitWidth() - StepV.countTrailingZeros();
7164 auto *NarrowTy = IntegerType::get(getContext(), NarrowWidth);
7165 auto *WideTy = Distance->getType();
7166
7167 const SCEV *Limit =
7168 getZeroExtendExpr(getTruncateExpr(ModuloResult, NarrowTy), WideTy);
7169 return ExitLimit(Limit, Limit, P);
7170 }
7171 }
7172
7173 // If the condition controls loop exit (the loop exits only if the expression
7174 // is true) and the addition is no-wrap we can use unsigned divide to
7175 // compute the backedge count. In this case, the step may not divide the
7176 // distance, but we don't care because if the condition is "missed" the loop
7177 // will have undefined behavior due to wrapping.
7178 if (ControlsExit && AddRec->hasNoSelfWrap()) {
7179 const SCEV *Exact =
7180 getUDivExpr(Distance, CountDown ? getNegativeSCEV(Step) : Step);
7181 return ExitLimit(Exact, Exact, P);
7182 }
7183
7184 // Then, try to solve the above equation provided that Start is constant.
7185 if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start)) {
7186 const SCEV *E = SolveLinEquationWithOverflow(
7187 StepC->getValue()->getValue(), -StartC->getValue()->getValue(), *this);
7188 return ExitLimit(E, E, P);
7189 }
7190 return getCouldNotCompute();
7191}
7192
7193/// HowFarToNonZero - Return the number of times a backedge checking the
7194/// specified value for nonzero will execute. If not computable, return
7195/// CouldNotCompute
7196ScalarEvolution::ExitLimit
7197ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) {
7198 // Loops that look like: while (X == 0) are very strange indeed. We don't
7199 // handle them yet except for the trivial case. This could be expanded in the
7200 // future as needed.
7201
7202 // If the value is a constant, check to see if it is known to be non-zero
7203 // already. If so, the backedge will execute zero times.
7204 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
7205 if (!C->getValue()->isNullValue())
7206 return getZero(C->getType());
7207 return getCouldNotCompute(); // Otherwise it will loop infinitely.
7208 }
7209
7210 // We could implement others, but I really doubt anyone writes loops like
7211 // this, and if they did, they would already be constant folded.
7212 return getCouldNotCompute();
7213}
7214
7215/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
7216/// (which may not be an immediate predecessor) which has exactly one
7217/// successor from which BB is reachable, or null if no such block is
7218/// found.
7219///
7220std::pair<BasicBlock *, BasicBlock *>
7221ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
7222 // If the block has a unique predecessor, then there is no path from the
7223 // predecessor to the block that does not go through the direct edge
7224 // from the predecessor to the block.
7225 if (BasicBlock *Pred = BB->getSinglePredecessor())
7226 return {Pred, BB};
7227
7228 // A loop's header is defined to be a block that dominates the loop.
7229 // If the header has a unique predecessor outside the loop, it must be
7230 // a block that has exactly one successor that can reach the loop.
7231 if (Loop *L = LI.getLoopFor(BB))
7232 return {L->getLoopPredecessor(), L->getHeader()};
7233
7234 return {nullptr, nullptr};
7235}
7236
7237/// HasSameValue - SCEV structural equivalence is usually sufficient for
7238/// testing whether two expressions are equal, however for the purposes of
7239/// looking for a condition guarding a loop, it can be useful to be a little
7240/// more general, since a front-end may have replicated the controlling
7241/// expression.
7242///
7243static bool HasSameValue(const SCEV *A, const SCEV *B) {
7244 // Quick check to see if they are the same SCEV.
7245 if (A == B) return true;
7246
7247 auto ComputesEqualValues = [](const Instruction *A, const Instruction *B) {
7248 // Not all instructions that are "identical" compute the same value. For
7249 // instance, two distinct alloca instructions allocating the same type are
7250 // identical and do not read memory; but compute distinct values.
7251 return A->isIdenticalTo(B) && (isa<BinaryOperator>(A) || isa<GetElementPtrInst>(A));
7252 };
7253
7254 // Otherwise, if they're both SCEVUnknown, it's possible that they hold
7255 // two different instructions with the same value. Check for this case.
7256 if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
7257 if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
7258 if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
7259 if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
7260 if (ComputesEqualValues(AI, BI))
7261 return true;
7262
7263 // Otherwise assume they may have a different value.
7264 return false;
7265}
7266
7267/// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
7268/// predicate Pred. Return true iff any changes were made.
7269///
7270bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
7271 const SCEV *&LHS, const SCEV *&RHS,
7272 unsigned Depth) {
7273 bool Changed = false;
7274
7275 // If we hit the max recursion limit bail out.
7276 if (Depth >= 3)
7277 return false;
7278
7279 // Canonicalize a constant to the right side.
7280 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
7281 // Check for both operands constant.
7282 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
7283 if (ConstantExpr::getICmp(Pred,
7284 LHSC->getValue(),
7285 RHSC->getValue())->isNullValue())
7286 goto trivially_false;
7287 else
7288 goto trivially_true;
7289 }
7290 // Otherwise swap the operands to put the constant on the right.
7291 std::swap(LHS, RHS);
7292 Pred = ICmpInst::getSwappedPredicate(Pred);
7293 Changed = true;
7294 }
7295
7296 // If we're comparing an addrec with a value which is loop-invariant in the
7297 // addrec's loop, put the addrec on the left. Also make a dominance check,
7298 // as both operands could be addrecs loop-invariant in each other's loop.
7299 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
7300 const Loop *L = AR->getLoop();
7301 if (isLoopInvariant(LHS, L) && properlyDominates(LHS, L->getHeader())) {
7302 std::swap(LHS, RHS);
7303 Pred = ICmpInst::getSwappedPredicate(Pred);
7304 Changed = true;
7305 }
7306 }
7307
7308 // If there's a constant operand, canonicalize comparisons with boundary
7309 // cases, and canonicalize *-or-equal comparisons to regular comparisons.
7310 if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
7311 const APInt &RA = RC->getAPInt();
7312 switch (Pred) {
7313 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7313)
;
7314 case ICmpInst::ICMP_EQ:
7315 case ICmpInst::ICMP_NE:
7316 // Fold ((-1) * %a) + %b == 0 (equivalent to %b-%a == 0) into %a == %b.
7317 if (!RA)
7318 if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(LHS))
7319 if (const SCEVMulExpr *ME = dyn_cast<SCEVMulExpr>(AE->getOperand(0)))
7320 if (AE->getNumOperands() == 2 && ME->getNumOperands() == 2 &&
7321 ME->getOperand(0)->isAllOnesValue()) {
7322 RHS = AE->getOperand(1);
7323 LHS = ME->getOperand(1);
7324 Changed = true;
7325 }
7326 break;
7327 case ICmpInst::ICMP_UGE:
7328 if ((RA - 1).isMinValue()) {
7329 Pred = ICmpInst::ICMP_NE;
7330 RHS = getConstant(RA - 1);
7331 Changed = true;
7332 break;
7333 }
7334 if (RA.isMaxValue()) {
7335 Pred = ICmpInst::ICMP_EQ;
7336 Changed = true;
7337 break;
7338 }
7339 if (RA.isMinValue()) goto trivially_true;
7340
7341 Pred = ICmpInst::ICMP_UGT;
7342 RHS = getConstant(RA - 1);
7343 Changed = true;
7344 break;
7345 case ICmpInst::ICMP_ULE:
7346 if ((RA + 1).isMaxValue()) {
7347 Pred = ICmpInst::ICMP_NE;
7348 RHS = getConstant(RA + 1);
7349 Changed = true;
7350 break;
7351 }
7352 if (RA.isMinValue()) {
7353 Pred = ICmpInst::ICMP_EQ;
7354 Changed = true;
7355 break;
7356 }
7357 if (RA.isMaxValue()) goto trivially_true;
7358
7359 Pred = ICmpInst::ICMP_ULT;
7360 RHS = getConstant(RA + 1);
7361 Changed = true;
7362 break;
7363 case ICmpInst::ICMP_SGE:
7364 if ((RA - 1).isMinSignedValue()) {
7365 Pred = ICmpInst::ICMP_NE;
7366 RHS = getConstant(RA - 1);
7367 Changed = true;
7368 break;
7369 }
7370 if (RA.isMaxSignedValue()) {
7371 Pred = ICmpInst::ICMP_EQ;
7372 Changed = true;
7373 break;
7374 }
7375 if (RA.isMinSignedValue()) goto trivially_true;
7376
7377 Pred = ICmpInst::ICMP_SGT;
7378 RHS = getConstant(RA - 1);
7379 Changed = true;
7380 break;
7381 case ICmpInst::ICMP_SLE:
7382 if ((RA + 1).isMaxSignedValue()) {
7383 Pred = ICmpInst::ICMP_NE;
7384 RHS = getConstant(RA + 1);
7385 Changed = true;
7386 break;
7387 }
7388 if (RA.isMinSignedValue()) {
7389 Pred = ICmpInst::ICMP_EQ;
7390 Changed = true;
7391 break;
7392 }
7393 if (RA.isMaxSignedValue()) goto trivially_true;
7394
7395 Pred = ICmpInst::ICMP_SLT;
7396 RHS = getConstant(RA + 1);
7397 Changed = true;
7398 break;
7399 case ICmpInst::ICMP_UGT:
7400 if (RA.isMinValue()) {
7401 Pred = ICmpInst::ICMP_NE;
7402 Changed = true;
7403 break;
7404 }
7405 if ((RA + 1).isMaxValue()) {
7406 Pred = ICmpInst::ICMP_EQ;
7407 RHS = getConstant(RA + 1);
7408 Changed = true;
7409 break;
7410 }
7411 if (RA.isMaxValue()) goto trivially_false;
7412 break;
7413 case ICmpInst::ICMP_ULT:
7414 if (RA.isMaxValue()) {
7415 Pred = ICmpInst::ICMP_NE;
7416 Changed = true;
7417 break;
7418 }
7419 if ((RA - 1).isMinValue()) {
7420 Pred = ICmpInst::ICMP_EQ;
7421 RHS = getConstant(RA - 1);
7422 Changed = true;
7423 break;
7424 }
7425 if (RA.isMinValue()) goto trivially_false;
7426 break;
7427 case ICmpInst::ICMP_SGT:
7428 if (RA.isMinSignedValue()) {
7429 Pred = ICmpInst::ICMP_NE;
7430 Changed = true;
7431 break;
7432 }
7433 if ((RA + 1).isMaxSignedValue()) {
7434 Pred = ICmpInst::ICMP_EQ;
7435 RHS = getConstant(RA + 1);
7436 Changed = true;
7437 break;
7438 }
7439 if (RA.isMaxSignedValue()) goto trivially_false;
7440 break;
7441 case ICmpInst::ICMP_SLT:
7442 if (RA.isMaxSignedValue()) {
7443 Pred = ICmpInst::ICMP_NE;
7444 Changed = true;
7445 break;
7446 }
7447 if ((RA - 1).isMinSignedValue()) {
7448 Pred = ICmpInst::ICMP_EQ;
7449 RHS = getConstant(RA - 1);
7450 Changed = true;
7451 break;
7452 }
7453 if (RA.isMinSignedValue()) goto trivially_false;
7454 break;
7455 }
7456 }
7457
7458 // Check for obvious equality.
7459 if (HasSameValue(LHS, RHS)) {
7460 if (ICmpInst::isTrueWhenEqual(Pred))
7461 goto trivially_true;
7462 if (ICmpInst::isFalseWhenEqual(Pred))
7463 goto trivially_false;
7464 }
7465
7466 // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
7467 // adding or subtracting 1 from one of the operands.
7468 switch (Pred) {
7469 case ICmpInst::ICMP_SLE:
7470 if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) {
7471 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
7472 SCEV::FlagNSW);
7473 Pred = ICmpInst::ICMP_SLT;
7474 Changed = true;
7475 } else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) {
7476 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
7477 SCEV::FlagNSW);
7478 Pred = ICmpInst::ICMP_SLT;
7479 Changed = true;
7480 }
7481 break;
7482 case ICmpInst::ICMP_SGE:
7483 if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) {
7484 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
7485 SCEV::FlagNSW);
7486 Pred = ICmpInst::ICMP_SGT;
7487 Changed = true;
7488 } else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) {
7489 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
7490 SCEV::FlagNSW);
7491 Pred = ICmpInst::ICMP_SGT;
7492 Changed = true;
7493 }
7494 break;
7495 case ICmpInst::ICMP_ULE:
7496 if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) {
7497 RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
7498 SCEV::FlagNUW);
7499 Pred = ICmpInst::ICMP_ULT;
7500 Changed = true;
7501 } else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) {
7502 LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS);
7503 Pred = ICmpInst::ICMP_ULT;
7504 Changed = true;
7505 }
7506 break;
7507 case ICmpInst::ICMP_UGE:
7508 if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) {
7509 RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS);
7510 Pred = ICmpInst::ICMP_UGT;
7511 Changed = true;
7512 } else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) {
7513 LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
7514 SCEV::FlagNUW);
7515 Pred = ICmpInst::ICMP_UGT;
7516 Changed = true;
7517 }
7518 break;
7519 default:
7520 break;
7521 }
7522
7523 // TODO: More simplifications are possible here.
7524
7525 // Recursively simplify until we either hit a recursion limit or nothing
7526 // changes.
7527 if (Changed)
7528 return SimplifyICmpOperands(Pred, LHS, RHS, Depth+1);
7529
7530 return Changed;
7531
7532trivially_true:
7533 // Return 0 == 0.
7534 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
7535 Pred = ICmpInst::ICMP_EQ;
7536 return true;
7537
7538trivially_false:
7539 // Return 0 != 0.
7540 LHS = RHS = getConstant(ConstantInt::getFalse(getContext()));
7541 Pred = ICmpInst::ICMP_NE;
7542 return true;
7543}
7544
7545bool ScalarEvolution::isKnownNegative(const SCEV *S) {
7546 return getSignedRange(S).getSignedMax().isNegative();
7547}
7548
7549bool ScalarEvolution::isKnownPositive(const SCEV *S) {
7550 return getSignedRange(S).getSignedMin().isStrictlyPositive();
7551}
7552
7553bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
7554 return !getSignedRange(S).getSignedMin().isNegative();
7555}
7556
7557bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
7558 return !getSignedRange(S).getSignedMax().isStrictlyPositive();
7559}
7560
7561bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
7562 return isKnownNegative(S) || isKnownPositive(S);
7563}
7564
7565bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
7566 const SCEV *LHS, const SCEV *RHS) {
7567 // Canonicalize the inputs first.
7568 (void)SimplifyICmpOperands(Pred, LHS, RHS);
7569
7570 // If LHS or RHS is an addrec, check to see if the condition is true in
7571 // every iteration of the loop.
7572 // If LHS and RHS are both addrec, both conditions must be true in
7573 // every iteration of the loop.
7574 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
7575 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
7576 bool LeftGuarded = false;
7577 bool RightGuarded = false;
7578 if (LAR) {
7579 const Loop *L = LAR->getLoop();
7580 if (isLoopEntryGuardedByCond(L, Pred, LAR->getStart(), RHS) &&
7581 isLoopBackedgeGuardedByCond(L, Pred, LAR->getPostIncExpr(*this), RHS)) {
7582 if (!RAR) return true;
7583 LeftGuarded = true;
7584 }
7585 }
7586 if (RAR) {
7587 const Loop *L = RAR->getLoop();
7588 if (isLoopEntryGuardedByCond(L, Pred, LHS, RAR->getStart()) &&
7589 isLoopBackedgeGuardedByCond(L, Pred, LHS, RAR->getPostIncExpr(*this))) {
7590 if (!LAR) return true;
7591 RightGuarded = true;
7592 }
7593 }
7594 if (LeftGuarded && RightGuarded)
7595 return true;
7596
7597 if (isKnownPredicateViaSplitting(Pred, LHS, RHS))
7598 return true;
7599
7600 // Otherwise see what can be done with known constant ranges.
7601 return isKnownPredicateViaConstantRanges(Pred, LHS, RHS);
7602}
7603
7604bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS,
7605 ICmpInst::Predicate Pred,
7606 bool &Increasing) {
7607 bool Result = isMonotonicPredicateImpl(LHS, Pred, Increasing);
7608
7609#ifndef NDEBUG
7610 // Verify an invariant: inverting the predicate should turn a monotonically
7611 // increasing change to a monotonically decreasing one, and vice versa.
7612 bool IncreasingSwapped;
7613 bool ResultSwapped = isMonotonicPredicateImpl(
7614 LHS, ICmpInst::getSwappedPredicate(Pred), IncreasingSwapped);
7615
7616 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7616, __PRETTY_FUNCTION__))
;
7617 if (ResultSwapped)
7618 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7619, __PRETTY_FUNCTION__))
7619 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7619, __PRETTY_FUNCTION__))
;
7620#endif
7621
7622 return Result;
7623}
7624
7625bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
7626 ICmpInst::Predicate Pred,
7627 bool &Increasing) {
7628
7629 // A zero step value for LHS means the induction variable is essentially a
7630 // loop invariant value. We don't really depend on the predicate actually
7631 // flipping from false to true (for increasing predicates, and the other way
7632 // around for decreasing predicates), all we care about is that *if* the
7633 // predicate changes then it only changes from false to true.
7634 //
7635 // A zero step value in itself is not very useful, but there may be places
7636 // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
7637 // as general as possible.
7638
7639 switch (Pred) {
7640 default:
7641 return false; // Conservative answer
7642
7643 case ICmpInst::ICMP_UGT:
7644 case ICmpInst::ICMP_UGE:
7645 case ICmpInst::ICMP_ULT:
7646 case ICmpInst::ICMP_ULE:
7647 if (!LHS->hasNoUnsignedWrap())
7648 return false;
7649
7650 Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE;
7651 return true;
7652
7653 case ICmpInst::ICMP_SGT:
7654 case ICmpInst::ICMP_SGE:
7655 case ICmpInst::ICMP_SLT:
7656 case ICmpInst::ICMP_SLE: {
7657 if (!LHS->hasNoSignedWrap())
7658 return false;
7659
7660 const SCEV *Step = LHS->getStepRecurrence(*this);
7661
7662 if (isKnownNonNegative(Step)) {
7663 Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE;
7664 return true;
7665 }
7666
7667 if (isKnownNonPositive(Step)) {
7668 Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE;
7669 return true;
7670 }
7671
7672 return false;
7673 }
7674
7675 }
7676
7677 llvm_unreachable("switch has default clause!")::llvm::llvm_unreachable_internal("switch has default clause!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7677)
;
7678}
7679
7680bool ScalarEvolution::isLoopInvariantPredicate(
7681 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS, const Loop *L,
7682 ICmpInst::Predicate &InvariantPred, const SCEV *&InvariantLHS,
7683 const SCEV *&InvariantRHS) {
7684
7685 // If there is a loop-invariant, force it into the RHS, otherwise bail out.
7686 if (!isLoopInvariant(RHS, L)) {
7687 if (!isLoopInvariant(LHS, L))
7688 return false;
7689
7690 std::swap(LHS, RHS);
7691 Pred = ICmpInst::getSwappedPredicate(Pred);
7692 }
7693
7694 const SCEVAddRecExpr *ArLHS = dyn_cast<SCEVAddRecExpr>(LHS);
7695 if (!ArLHS || ArLHS->getLoop() != L)
7696 return false;
7697
7698 bool Increasing;
7699 if (!isMonotonicPredicate(ArLHS, Pred, Increasing))
7700 return false;
7701
7702 // If the predicate "ArLHS `Pred` RHS" monotonically increases from false to
7703 // true as the loop iterates, and the backedge is control dependent on
7704 // "ArLHS `Pred` RHS" == true then we can reason as follows:
7705 //
7706 // * if the predicate was false in the first iteration then the predicate
7707 // is never evaluated again, since the loop exits without taking the
7708 // backedge.
7709 // * if the predicate was true in the first iteration then it will
7710 // continue to be true for all future iterations since it is
7711 // monotonically increasing.
7712 //
7713 // For both the above possibilities, we can replace the loop varying
7714 // predicate with its value on the first iteration of the loop (which is
7715 // loop invariant).
7716 //
7717 // A similar reasoning applies for a monotonically decreasing predicate, by
7718 // replacing true with false and false with true in the above two bullets.
7719
7720 auto P = Increasing ? Pred : ICmpInst::getInversePredicate(Pred);
7721
7722 if (!isLoopBackedgeGuardedByCond(L, P, LHS, RHS))
7723 return false;
7724
7725 InvariantPred = Pred;
7726 InvariantLHS = ArLHS->getStart();
7727 InvariantRHS = RHS;
7728 return true;
7729}
7730
7731bool ScalarEvolution::isKnownPredicateViaConstantRanges(
7732 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
7733 if (HasSameValue(LHS, RHS))
7734 return ICmpInst::isTrueWhenEqual(Pred);
7735
7736 // This code is split out from isKnownPredicate because it is called from
7737 // within isLoopEntryGuardedByCond.
7738
7739 auto CheckRanges =
7740 [&](const ConstantRange &RangeLHS, const ConstantRange &RangeRHS) {
7741 return ConstantRange::makeSatisfyingICmpRegion(Pred, RangeRHS)
7742 .contains(RangeLHS);
7743 };
7744
7745 // The check at the top of the function catches the case where the values are
7746 // known to be equal.
7747 if (Pred == CmpInst::ICMP_EQ)
7748 return false;
7749
7750 if (Pred == CmpInst::ICMP_NE)
7751 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS)) ||
7752 CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS)) ||
7753 isKnownNonZero(getMinusSCEV(LHS, RHS));
7754
7755 if (CmpInst::isSigned(Pred))
7756 return CheckRanges(getSignedRange(LHS), getSignedRange(RHS));
7757
7758 return CheckRanges(getUnsignedRange(LHS), getUnsignedRange(RHS));
7759}
7760
7761bool ScalarEvolution::isKnownPredicateViaNoOverflow(ICmpInst::Predicate Pred,
7762 const SCEV *LHS,
7763 const SCEV *RHS) {
7764
7765 // Match Result to (X + Y)<ExpectedFlags> where Y is a constant integer.
7766 // Return Y via OutY.
7767 auto MatchBinaryAddToConst =
7768 [this](const SCEV *Result, const SCEV *X, APInt &OutY,
7769 SCEV::NoWrapFlags ExpectedFlags) {
7770 const SCEV *NonConstOp, *ConstOp;
7771 SCEV::NoWrapFlags FlagsPresent;
7772
7773 if (!splitBinaryAdd(Result, ConstOp, NonConstOp, FlagsPresent) ||
7774 !isa<SCEVConstant>(ConstOp) || NonConstOp != X)
7775 return false;
7776
7777 OutY = cast<SCEVConstant>(ConstOp)->getAPInt();
7778 return (FlagsPresent & ExpectedFlags) == ExpectedFlags;
7779 };
7780
7781 APInt C;
7782
7783 switch (Pred) {
7784 default:
7785 break;
7786
7787 case ICmpInst::ICMP_SGE:
7788 std::swap(LHS, RHS);
7789 case ICmpInst::ICMP_SLE:
7790 // X s<= (X + C)<nsw> if C >= 0
7791 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) && C.isNonNegative())
7792 return true;
7793
7794 // (X + C)<nsw> s<= X if C <= 0
7795 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) &&
7796 !C.isStrictlyPositive())
7797 return true;
7798 break;
7799
7800 case ICmpInst::ICMP_SGT:
7801 std::swap(LHS, RHS);
7802 case ICmpInst::ICMP_SLT:
7803 // X s< (X + C)<nsw> if C > 0
7804 if (MatchBinaryAddToConst(RHS, LHS, C, SCEV::FlagNSW) &&
7805 C.isStrictlyPositive())
7806 return true;
7807
7808 // (X + C)<nsw> s< X if C < 0
7809 if (MatchBinaryAddToConst(LHS, RHS, C, SCEV::FlagNSW) && C.isNegative())
7810 return true;
7811 break;
7812 }
7813
7814 return false;
7815}
7816
7817bool ScalarEvolution::isKnownPredicateViaSplitting(ICmpInst::Predicate Pred,
7818 const SCEV *LHS,
7819 const SCEV *RHS) {
7820 if (Pred != ICmpInst::ICMP_ULT || ProvingSplitPredicate)
7821 return false;
7822
7823 // Allowing arbitrary number of activations of isKnownPredicateViaSplitting on
7824 // the stack can result in exponential time complexity.
7825 SaveAndRestore<bool> Restore(ProvingSplitPredicate, true);
7826
7827 // If L >= 0 then I `ult` L <=> I >= 0 && I `slt` L
7828 //
7829 // To prove L >= 0 we use isKnownNonNegative whereas to prove I >= 0 we use
7830 // isKnownPredicate. isKnownPredicate is more powerful, but also more
7831 // expensive; and using isKnownNonNegative(RHS) is sufficient for most of the
7832 // interesting cases seen in practice. We can consider "upgrading" L >= 0 to
7833 // use isKnownPredicate later if needed.
7834 return isKnownNonNegative(RHS) &&
7835 isKnownPredicate(CmpInst::ICMP_SGE, LHS, getZero(LHS->getType())) &&
7836 isKnownPredicate(CmpInst::ICMP_SLT, LHS, RHS);
7837}
7838
7839bool ScalarEvolution::isImpliedViaGuard(BasicBlock *BB,
7840 ICmpInst::Predicate Pred,
7841 const SCEV *LHS, const SCEV *RHS) {
7842 // No need to even try if we know the module has no guards.
7843 if (!HasGuards)
7844 return false;
7845
7846 return any_of(*BB, [&](Instruction &I) {
7847 using namespace llvm::PatternMatch;
7848
7849 Value *Condition;
7850 return match(&I, m_Intrinsic<Intrinsic::experimental_guard>(
7851 m_Value(Condition))) &&
7852 isImpliedCond(Pred, LHS, RHS, Condition, false);
7853 });
7854}
7855
7856/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
7857/// protected by a conditional between LHS and RHS. This is used to
7858/// to eliminate casts.
7859bool
7860ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
7861 ICmpInst::Predicate Pred,
7862 const SCEV *LHS, const SCEV *RHS) {
7863 // Interpret a null as meaning no loop, where there is obviously no guard
7864 // (interprocedural conditions notwithstanding).
7865 if (!L) return true;
7866
7867 if (isKnownPredicateViaConstantRanges(Pred, LHS, RHS))
7868 return true;
7869
7870 BasicBlock *Latch = L->getLoopLatch();
7871 if (!Latch)
7872 return false;
7873
7874 BranchInst *LoopContinuePredicate =
7875 dyn_cast<BranchInst>(Latch->getTerminator());
7876 if (LoopContinuePredicate && LoopContinuePredicate->isConditional() &&
7877 isImpliedCond(Pred, LHS, RHS,
7878 LoopContinuePredicate->getCondition(),
7879 LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
7880 return true;
7881
7882 // We don't want more than one activation of the following loops on the stack
7883 // -- that can lead to O(n!) time complexity.
7884 if (WalkingBEDominatingConds)
7885 return false;
7886
7887 SaveAndRestore<bool> ClearOnExit(WalkingBEDominatingConds, true);
7888
7889 // See if we can exploit a trip count to prove the predicate.
7890 const auto &BETakenInfo = getBackedgeTakenInfo(L);
7891 const SCEV *LatchBECount = BETakenInfo.getExact(Latch, this);
7892 if (LatchBECount != getCouldNotCompute()) {
7893 // We know that Latch branches back to the loop header exactly
7894 // LatchBECount times. This means the backdege condition at Latch is
7895 // equivalent to "{0,+,1} u< LatchBECount".
7896 Type *Ty = LatchBECount->getType();
7897 auto NoWrapFlags = SCEV::NoWrapFlags(SCEV::FlagNUW | SCEV::FlagNW);
7898 const SCEV *LoopCounter =
7899 getAddRecExpr(getZero(Ty), getOne(Ty), L, NoWrapFlags);
7900 if (isImpliedCond(Pred, LHS, RHS, ICmpInst::ICMP_ULT, LoopCounter,
7901 LatchBECount))
7902 return true;
7903 }
7904
7905 // Check conditions due to any @llvm.assume intrinsics.
7906 for (auto &AssumeVH : AC.assumptions()) {
7907 if (!AssumeVH)
7908 continue;
7909 auto *CI = cast<CallInst>(AssumeVH);
7910 if (!DT.dominates(CI, Latch->getTerminator()))
7911 continue;
7912
7913 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
7914 return true;
7915 }
7916
7917 // If the loop is not reachable from the entry block, we risk running into an
7918 // infinite loop as we walk up into the dom tree. These loops do not matter
7919 // anyway, so we just return a conservative answer when we see them.
7920 if (!DT.isReachableFromEntry(L->getHeader()))
7921 return false;
7922
7923 if (isImpliedViaGuard(Latch, Pred, LHS, RHS))
7924 return true;
7925
7926 for (DomTreeNode *DTN = DT[Latch], *HeaderDTN = DT[L->getHeader()];
7927 DTN != HeaderDTN; DTN = DTN->getIDom()) {
7928
7929 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7929, __PRETTY_FUNCTION__))
;
7930
7931 BasicBlock *BB = DTN->getBlock();
7932 if (isImpliedViaGuard(BB, Pred, LHS, RHS))
7933 return true;
7934
7935 BasicBlock *PBB = BB->getSinglePredecessor();
7936 if (!PBB)
7937 continue;
7938
7939 BranchInst *ContinuePredicate = dyn_cast<BranchInst>(PBB->getTerminator());
7940 if (!ContinuePredicate || !ContinuePredicate->isConditional())
7941 continue;
7942
7943 Value *Condition = ContinuePredicate->getCondition();
7944
7945 // If we have an edge `E` within the loop body that dominates the only
7946 // latch, the condition guarding `E` also guards the backedge. This
7947 // reasoning works only for loops with a single latch.
7948
7949 BasicBlockEdge DominatingEdge(PBB, BB);
7950 if (DominatingEdge.isSingleEdge()) {
7951 // We're constructively (and conservatively) enumerating edges within the
7952 // loop body that dominate the latch. The dominator tree better agree
7953 // with us on this:
7954 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 7954, __PRETTY_FUNCTION__))
;
7955
7956 if (isImpliedCond(Pred, LHS, RHS, Condition,
7957 BB != ContinuePredicate->getSuccessor(0)))
7958 return true;
7959 }
7960 }
7961
7962 return false;
7963}
7964
7965/// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
7966/// by a conditional between LHS and RHS. This is used to help avoid max
7967/// expressions in loop trip counts, and to eliminate casts.
7968bool
7969ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
7970 ICmpInst::Predicate Pred,
7971 const SCEV *LHS, const SCEV *RHS) {
7972 // Interpret a null as meaning no loop, where there is obviously no guard
7973 // (interprocedural conditions notwithstanding).
7974 if (!L) return false;
7975
7976 if (isKnownPredicateViaConstantRanges(Pred, LHS, RHS))
7977 return true;
7978
7979 // Starting at the loop predecessor, climb up the predecessor chain, as long
7980 // as there are predecessors that can be found that have unique successors
7981 // leading to the original header.
7982 for (std::pair<BasicBlock *, BasicBlock *>
7983 Pair(L->getLoopPredecessor(), L->getHeader());
7984 Pair.first;
7985 Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
7986
7987 if (isImpliedViaGuard(Pair.first, Pred, LHS, RHS))
7988 return true;
7989
7990 BranchInst *LoopEntryPredicate =
7991 dyn_cast<BranchInst>(Pair.first->getTerminator());
7992 if (!LoopEntryPredicate ||
7993 LoopEntryPredicate->isUnconditional())
7994 continue;
7995
7996 if (isImpliedCond(Pred, LHS, RHS,
7997 LoopEntryPredicate->getCondition(),
7998 LoopEntryPredicate->getSuccessor(0) != Pair.second))
7999 return true;
8000 }
8001
8002 // Check conditions due to any @llvm.assume intrinsics.
8003 for (auto &AssumeVH : AC.assumptions()) {
8004 if (!AssumeVH)
8005 continue;
8006 auto *CI = cast<CallInst>(AssumeVH);
8007 if (!DT.dominates(CI, L->getHeader()))
8008 continue;
8009
8010 if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
8011 return true;
8012 }
8013
8014 return false;
8015}
8016
8017namespace {
8018/// RAII wrapper to prevent recursive application of isImpliedCond.
8019/// ScalarEvolution's PendingLoopPredicates set must be empty unless we are
8020/// currently evaluating isImpliedCond.
8021struct MarkPendingLoopPredicate {
8022 Value *Cond;
8023 DenseSet<Value*> &LoopPreds;
8024 bool Pending;
8025
8026 MarkPendingLoopPredicate(Value *C, DenseSet<Value*> &LP)
8027 : Cond(C), LoopPreds(LP) {
8028 Pending = !LoopPreds.insert(Cond).second;
8029 }
8030 ~MarkPendingLoopPredicate() {
8031 if (!Pending)
8032 LoopPreds.erase(Cond);
8033 }
8034};
8035} // end anonymous namespace
8036
8037/// isImpliedCond - Test whether the condition described by Pred, LHS,
8038/// and RHS is true whenever the given Cond value evaluates to true.
8039bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
8040 const SCEV *LHS, const SCEV *RHS,
8041 Value *FoundCondValue,
8042 bool Inverse) {
8043 MarkPendingLoopPredicate Mark(FoundCondValue, PendingLoopPredicates);
8044 if (Mark.Pending)
8045 return false;
8046
8047 // Recursively handle And and Or conditions.
8048 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FoundCondValue)) {
8049 if (BO->getOpcode() == Instruction::And) {
8050 if (!Inverse)
8051 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
8052 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
8053 } else if (BO->getOpcode() == Instruction::Or) {
8054 if (Inverse)
8055 return isImpliedCond(Pred, LHS, RHS, BO->getOperand(0), Inverse) ||
8056 isImpliedCond(Pred, LHS, RHS, BO->getOperand(1), Inverse);
8057 }
8058 }
8059
8060 ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
8061 if (!ICI) return false;
8062
8063 // Now that we found a conditional branch that dominates the loop or controls
8064 // the loop latch. Check to see if it is the comparison we are looking for.
8065 ICmpInst::Predicate FoundPred;
8066 if (Inverse)
8067 FoundPred = ICI->getInversePredicate();
8068 else
8069 FoundPred = ICI->getPredicate();
8070
8071 const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
8072 const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
8073
8074 return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS);
8075}
8076
8077bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
8078 const SCEV *RHS,
8079 ICmpInst::Predicate FoundPred,
8080 const SCEV *FoundLHS,
8081 const SCEV *FoundRHS) {
8082 // Balance the types.
8083 if (getTypeSizeInBits(LHS->getType()) <
8084 getTypeSizeInBits(FoundLHS->getType())) {
8085 if (CmpInst::isSigned(Pred)) {
8086 LHS = getSignExtendExpr(LHS, FoundLHS->getType());
8087 RHS = getSignExtendExpr(RHS, FoundLHS->getType());
8088 } else {
8089 LHS = getZeroExtendExpr(LHS, FoundLHS->getType());
8090 RHS = getZeroExtendExpr(RHS, FoundLHS->getType());
8091 }
8092 } else if (getTypeSizeInBits(LHS->getType()) >
8093 getTypeSizeInBits(FoundLHS->getType())) {
8094 if (CmpInst::isSigned(FoundPred)) {
8095 FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
8096 FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
8097 } else {
8098 FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
8099 FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
8100 }
8101 }
8102
8103 // Canonicalize the query to match the way instcombine will have
8104 // canonicalized the comparison.
8105 if (SimplifyICmpOperands(Pred, LHS, RHS))
8106 if (LHS == RHS)
8107 return CmpInst::isTrueWhenEqual(Pred);
8108 if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
8109 if (FoundLHS == FoundRHS)
8110 return CmpInst::isFalseWhenEqual(FoundPred);
8111
8112 // Check to see if we can make the LHS or RHS match.
8113 if (LHS == FoundRHS || RHS == FoundLHS) {
8114 if (isa<SCEVConstant>(RHS)) {
8115 std::swap(FoundLHS, FoundRHS);
8116 FoundPred = ICmpInst::getSwappedPredicate(FoundPred);
8117 } else {
8118 std::swap(LHS, RHS);
8119 Pred = ICmpInst::getSwappedPredicate(Pred);
8120 }
8121 }
8122
8123 // Check whether the found predicate is the same as the desired predicate.
8124 if (FoundPred == Pred)
8125 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
8126
8127 // Check whether swapping the found predicate makes it the same as the
8128 // desired predicate.
8129 if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) {
8130 if (isa<SCEVConstant>(RHS))
8131 return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS);
8132 else
8133 return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred),
8134 RHS, LHS, FoundLHS, FoundRHS);
8135 }
8136
8137 // Unsigned comparison is the same as signed comparison when both the operands
8138 // are non-negative.
8139 if (CmpInst::isUnsigned(FoundPred) &&
8140 CmpInst::getSignedPredicate(FoundPred) == Pred &&
8141 isKnownNonNegative(FoundLHS) && isKnownNonNegative(FoundRHS))
8142 return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
8143
8144 // Check if we can make progress by sharpening ranges.
8145 if (FoundPred == ICmpInst::ICMP_NE &&
8146 (isa<SCEVConstant>(FoundLHS) || isa<SCEVConstant>(FoundRHS))) {
8147
8148 const SCEVConstant *C = nullptr;
8149 const SCEV *V = nullptr;
8150
8151 if (isa<SCEVConstant>(FoundLHS)) {
8152 C = cast<SCEVConstant>(FoundLHS);
8153 V = FoundRHS;
8154 } else {
8155 C = cast<SCEVConstant>(FoundRHS);
8156 V = FoundLHS;
8157 }
8158
8159 // The guarding predicate tells us that C != V. If the known range
8160 // of V is [C, t), we can sharpen the range to [C + 1, t). The
8161 // range we consider has to correspond to same signedness as the
8162 // predicate we're interested in folding.
8163
8164 APInt Min = ICmpInst::isSigned(Pred) ?
8165 getSignedRange(V).getSignedMin() : getUnsignedRange(V).getUnsignedMin();
8166
8167 if (Min == C->getAPInt()) {
8168 // Given (V >= Min && V != Min) we conclude V >= (Min + 1).
8169 // This is true even if (Min + 1) wraps around -- in case of
8170 // wraparound, (Min + 1) < Min, so (V >= Min => V >= (Min + 1)).
8171
8172 APInt SharperMin = Min + 1;
8173
8174 switch (Pred) {
8175 case ICmpInst::ICMP_SGE:
8176 case ICmpInst::ICMP_UGE:
8177 // We know V `Pred` SharperMin. If this implies LHS `Pred`
8178 // RHS, we're done.
8179 if (isImpliedCondOperands(Pred, LHS, RHS, V,
8180 getConstant(SharperMin)))
8181 return true;
8182
8183 case ICmpInst::ICMP_SGT:
8184 case ICmpInst::ICMP_UGT:
8185 // We know from the range information that (V `Pred` Min ||
8186 // V == Min). We know from the guarding condition that !(V
8187 // == Min). This gives us
8188 //
8189 // V `Pred` Min || V == Min && !(V == Min)
8190 // => V `Pred` Min
8191 //
8192 // If V `Pred` Min implies LHS `Pred` RHS, we're done.
8193
8194 if (isImpliedCondOperands(Pred, LHS, RHS, V, getConstant(Min)))
8195 return true;
8196
8197 default:
8198 // No change
8199 break;
8200 }
8201 }
8202 }
8203
8204 // Check whether the actual condition is beyond sufficient.
8205 if (FoundPred == ICmpInst::ICMP_EQ)
8206 if (ICmpInst::isTrueWhenEqual(Pred))
8207 if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS))
8208 return true;
8209 if (Pred == ICmpInst::ICMP_NE)
8210 if (!ICmpInst::isTrueWhenEqual(FoundPred))
8211 if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS))
8212 return true;
8213
8214 // Otherwise assume the worst.
8215 return false;
8216}
8217
8218bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
8219 const SCEV *&L, const SCEV *&R,
8220 SCEV::NoWrapFlags &Flags) {
8221 const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
8222 if (!AE || AE->getNumOperands() != 2)
8223 return false;
8224
8225 L = AE->getOperand(0);
8226 R = AE->getOperand(1);
8227 Flags = AE->getNoWrapFlags();
8228 return true;
8229}
8230
8231bool ScalarEvolution::computeConstantDifference(const SCEV *Less,
8232 const SCEV *More,
8233 APInt &C) {
8234 // We avoid subtracting expressions here because this function is usually
8235 // fairly deep in the call stack (i.e. is called many times).
8236
8237 if (isa<SCEVAddRecExpr>(Less) && isa<SCEVAddRecExpr>(More)) {
8238 const auto *LAR = cast<SCEVAddRecExpr>(Less);
8239 const auto *MAR = cast<SCEVAddRecExpr>(More);
8240
8241 if (LAR->getLoop() != MAR->getLoop())
8242 return false;
8243
8244 // We look at affine expressions only; not for correctness but to keep
8245 // getStepRecurrence cheap.
8246 if (!LAR->isAffine() || !MAR->isAffine())
8247 return false;
8248
8249 if (LAR->getStepRecurrence(*this) != MAR->getStepRecurrence(*this))
8250 return false;
8251
8252 Less = LAR->getStart();
8253 More = MAR->getStart();
8254
8255 // fall through
8256 }
8257
8258 if (isa<SCEVConstant>(Less) && isa<SCEVConstant>(More)) {
8259 const auto &M = cast<SCEVConstant>(More)->getAPInt();
8260 const auto &L = cast<SCEVConstant>(Less)->getAPInt();
8261 C = M - L;
8262 return true;
8263 }
8264
8265 const SCEV *L, *R;
8266 SCEV::NoWrapFlags Flags;
8267 if (splitBinaryAdd(Less, L, R, Flags))
8268 if (const auto *LC = dyn_cast<SCEVConstant>(L))
8269 if (R == More) {
8270 C = -(LC->getAPInt());
8271 return true;
8272 }
8273
8274 if (splitBinaryAdd(More, L, R, Flags))
8275 if (const auto *LC = dyn_cast<SCEVConstant>(L))
8276 if (R == Less) {
8277 C = LC->getAPInt();
8278 return true;
8279 }
8280
8281 return false;
8282}
8283
8284bool ScalarEvolution::isImpliedCondOperandsViaNoOverflow(
8285 ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS,
8286 const SCEV *FoundLHS, const SCEV *FoundRHS) {
8287 if (Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_ULT)
8288 return false;
8289
8290 const auto *AddRecLHS = dyn_cast<SCEVAddRecExpr>(LHS);
8291 if (!AddRecLHS)
8292 return false;
8293
8294 const auto *AddRecFoundLHS = dyn_cast<SCEVAddRecExpr>(FoundLHS);
8295 if (!AddRecFoundLHS)
8296 return false;
8297
8298 // We'd like to let SCEV reason about control dependencies, so we constrain
8299 // both the inequalities to be about add recurrences on the same loop. This
8300 // way we can use isLoopEntryGuardedByCond later.
8301
8302 const Loop *L = AddRecFoundLHS->getLoop();
8303 if (L != AddRecLHS->getLoop())
8304 return false;
8305
8306 // FoundLHS u< FoundRHS u< -C => (FoundLHS + C) u< (FoundRHS + C) ... (1)
8307 //
8308 // FoundLHS s< FoundRHS s< INT_MIN - C => (FoundLHS + C) s< (FoundRHS + C)
8309 // ... (2)
8310 //
8311 // Informal proof for (2), assuming (1) [*]:
8312 //
8313 // We'll also assume (A s< B) <=> ((A + INT_MIN) u< (B + INT_MIN)) ... (3)[**]
8314 //
8315 // Then
8316 //
8317 // FoundLHS s< FoundRHS s< INT_MIN - C
8318 // <=> (FoundLHS + INT_MIN) u< (FoundRHS + INT_MIN) u< -C [ using (3) ]
8319 // <=> (FoundLHS + INT_MIN + C) u< (FoundRHS + INT_MIN + C) [ using (1) ]
8320 // <=> (FoundLHS + INT_MIN + C + INT_MIN) s<
8321 // (FoundRHS + INT_MIN + C + INT_MIN) [ using (3) ]
8322 // <=> FoundLHS + C s< FoundRHS + C
8323 //
8324 // [*]: (1) can be proved by ruling out overflow.
8325 //
8326 // [**]: This can be proved by analyzing all the four possibilities:
8327 // (A s< 0, B s< 0), (A s< 0, B s>= 0), (A s>= 0, B s< 0) and
8328 // (A s>= 0, B s>= 0).
8329 //
8330 // Note:
8331 // Despite (2), "FoundRHS s< INT_MIN - C" does not mean that "FoundRHS + C"
8332 // will not sign underflow. For instance, say FoundLHS = (i8 -128), FoundRHS
8333 // = (i8 -127) and C = (i8 -100). Then INT_MIN - C = (i8 -28), and FoundRHS
8334 // s< (INT_MIN - C). Lack of sign overflow / underflow in "FoundRHS + C" is
8335 // neither necessary nor sufficient to prove "(FoundLHS + C) s< (FoundRHS +
8336 // C)".
8337
8338 APInt LDiff, RDiff;
8339 if (!computeConstantDifference(FoundLHS, LHS, LDiff) ||
8340 !computeConstantDifference(FoundRHS, RHS, RDiff) ||
8341 LDiff != RDiff)
8342 return false;
8343
8344 if (LDiff == 0)
8345 return true;
8346
8347 APInt FoundRHSLimit;
8348
8349 if (Pred == CmpInst::ICMP_ULT) {
8350 FoundRHSLimit = -RDiff;
8351 } else {
8352 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8352, __PRETTY_FUNCTION__))
;
8353 FoundRHSLimit = APInt::getSignedMinValue(getTypeSizeInBits(RHS->getType())) - RDiff;
8354 }
8355
8356 // Try to prove (1) or (2), as needed.
8357 return isLoopEntryGuardedByCond(L, Pred, FoundRHS,
8358 getConstant(FoundRHSLimit));
8359}
8360
8361/// isImpliedCondOperands - Test whether the condition described by Pred,
8362/// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
8363/// and FoundRHS is true.
8364bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
8365 const SCEV *LHS, const SCEV *RHS,
8366 const SCEV *FoundLHS,
8367 const SCEV *FoundRHS) {
8368 if (isImpliedCondOperandsViaRanges(Pred, LHS, RHS, FoundLHS, FoundRHS))
8369 return true;
8370
8371 if (isImpliedCondOperandsViaNoOverflow(Pred, LHS, RHS, FoundLHS, FoundRHS))
8372 return true;
8373
8374 return isImpliedCondOperandsHelper(Pred, LHS, RHS,
8375 FoundLHS, FoundRHS) ||
8376 // ~x < ~y --> x > y
8377 isImpliedCondOperandsHelper(Pred, LHS, RHS,
8378 getNotSCEV(FoundRHS),
8379 getNotSCEV(FoundLHS));
8380}
8381
8382
8383/// If Expr computes ~A, return A else return nullptr
8384static const SCEV *MatchNotExpr(const SCEV *Expr) {
8385 const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Expr);
8386 if (!Add || Add->getNumOperands() != 2 ||
8387 !Add->getOperand(0)->isAllOnesValue())
8388 return nullptr;
8389
8390 const SCEVMulExpr *AddRHS = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
8391 if (!AddRHS || AddRHS->getNumOperands() != 2 ||
8392 !AddRHS->getOperand(0)->isAllOnesValue())
8393 return nullptr;
8394
8395 return AddRHS->getOperand(1);
8396}
8397
8398
8399/// Is MaybeMaxExpr an SMax or UMax of Candidate and some other values?
8400template<typename MaxExprType>
8401static bool IsMaxConsistingOf(const SCEV *MaybeMaxExpr,
8402 const SCEV *Candidate) {
8403 const MaxExprType *MaxExpr = dyn_cast<MaxExprType>(MaybeMaxExpr);
8404 if (!MaxExpr) return false;
8405
8406 return find(MaxExpr->operands(), Candidate) != MaxExpr->op_end();
8407}
8408
8409
8410/// Is MaybeMinExpr an SMin or UMin of Candidate and some other values?
8411template<typename MaxExprType>
8412static bool IsMinConsistingOf(ScalarEvolution &SE,
8413 const SCEV *MaybeMinExpr,
8414 const SCEV *Candidate) {
8415 const SCEV *MaybeMaxExpr = MatchNotExpr(MaybeMinExpr);
8416 if (!MaybeMaxExpr)
8417 return false;
8418
8419 return IsMaxConsistingOf<MaxExprType>(MaybeMaxExpr, SE.getNotSCEV(Candidate));
8420}
8421
8422static bool IsKnownPredicateViaAddRecStart(ScalarEvolution &SE,
8423 ICmpInst::Predicate Pred,
8424 const SCEV *LHS, const SCEV *RHS) {
8425
8426 // If both sides are affine addrecs for the same loop, with equal
8427 // steps, and we know the recurrences don't wrap, then we only
8428 // need to check the predicate on the starting values.
8429
8430 if (!ICmpInst::isRelational(Pred))
8431 return false;
8432
8433 const SCEVAddRecExpr *LAR = dyn_cast<SCEVAddRecExpr>(LHS);
8434 if (!LAR)
8435 return false;
8436 const SCEVAddRecExpr *RAR = dyn_cast<SCEVAddRecExpr>(RHS);
8437 if (!RAR)
8438 return false;
8439 if (LAR->getLoop() != RAR->getLoop())
8440 return false;
8441 if (!LAR->isAffine() || !RAR->isAffine())
8442 return false;
8443
8444 if (LAR->getStepRecurrence(SE) != RAR->getStepRecurrence(SE))
8445 return false;
8446
8447 SCEV::NoWrapFlags NW = ICmpInst::isSigned(Pred) ?
8448 SCEV::FlagNSW : SCEV::FlagNUW;
8449 if (!LAR->getNoWrapFlags(NW) || !RAR->getNoWrapFlags(NW))
8450 return false;
8451
8452 return SE.isKnownPredicate(Pred, LAR->getStart(), RAR->getStart());
8453}
8454
8455/// Is LHS `Pred` RHS true on the virtue of LHS or RHS being a Min or Max
8456/// expression?
8457static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
8458 ICmpInst::Predicate Pred,
8459 const SCEV *LHS, const SCEV *RHS) {
8460 switch (Pred) {
8461 default:
8462 return false;
8463
8464 case ICmpInst::ICMP_SGE:
8465 std::swap(LHS, RHS);
8466 // fall through
8467 case ICmpInst::ICMP_SLE:
8468 return
8469 // min(A, ...) <= A
8470 IsMinConsistingOf<SCEVSMaxExpr>(SE, LHS, RHS) ||
8471 // A <= max(A, ...)
8472 IsMaxConsistingOf<SCEVSMaxExpr>(RHS, LHS);
8473
8474 case ICmpInst::ICMP_UGE:
8475 std::swap(LHS, RHS);
8476 // fall through
8477 case ICmpInst::ICMP_ULE:
8478 return
8479 // min(A, ...) <= A
8480 IsMinConsistingOf<SCEVUMaxExpr>(SE, LHS, RHS) ||
8481 // A <= max(A, ...)
8482 IsMaxConsistingOf<SCEVUMaxExpr>(RHS, LHS);
8483 }
8484
8485 llvm_unreachable("covered switch fell through?!")::llvm::llvm_unreachable_internal("covered switch fell through?!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8485)
;
8486}
8487
8488/// isImpliedCondOperandsHelper - Test whether the condition described by
8489/// Pred, LHS, and RHS is true whenever the condition described by Pred,
8490/// FoundLHS, and FoundRHS is true.
8491bool
8492ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
8493 const SCEV *LHS, const SCEV *RHS,
8494 const SCEV *FoundLHS,
8495 const SCEV *FoundRHS) {
8496 auto IsKnownPredicateFull =
8497 [this](ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
8498 return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
8499 IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
8500 IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
8501 isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
8502 };
8503
8504 switch (Pred) {
8505 default: llvm_unreachable("Unexpected ICmpInst::Predicate value!")::llvm::llvm_unreachable_internal("Unexpected ICmpInst::Predicate value!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8505)
;
8506 case ICmpInst::ICMP_EQ:
8507 case ICmpInst::ICMP_NE:
8508 if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
8509 return true;
8510 break;
8511 case ICmpInst::ICMP_SLT:
8512 case ICmpInst::ICMP_SLE:
8513 if (IsKnownPredicateFull(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
8514 IsKnownPredicateFull(ICmpInst::ICMP_SGE, RHS, FoundRHS))
8515 return true;
8516 break;
8517 case ICmpInst::ICMP_SGT:
8518 case ICmpInst::ICMP_SGE:
8519 if (IsKnownPredicateFull(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
8520 IsKnownPredicateFull(ICmpInst::ICMP_SLE, RHS, FoundRHS))
8521 return true;
8522 break;
8523 case ICmpInst::ICMP_ULT:
8524 case ICmpInst::ICMP_ULE:
8525 if (IsKnownPredicateFull(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
8526 IsKnownPredicateFull(ICmpInst::ICMP_UGE, RHS, FoundRHS))
8527 return true;
8528 break;
8529 case ICmpInst::ICMP_UGT:
8530 case ICmpInst::ICMP_UGE:
8531 if (IsKnownPredicateFull(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
8532 IsKnownPredicateFull(ICmpInst::ICMP_ULE, RHS, FoundRHS))
8533 return true;
8534 break;
8535 }
8536
8537 return false;
8538}
8539
8540/// isImpliedCondOperandsViaRanges - helper function for isImpliedCondOperands.
8541/// Tries to get cases like "X `sgt` 0 => X - 1 `sgt` -1".
8542bool ScalarEvolution::isImpliedCondOperandsViaRanges(ICmpInst::Predicate Pred,
8543 const SCEV *LHS,
8544 const SCEV *RHS,
8545 const SCEV *FoundLHS,
8546 const SCEV *FoundRHS) {
8547 if (!isa<SCEVConstant>(RHS) || !isa<SCEVConstant>(FoundRHS))
8548 // The restriction on `FoundRHS` be lifted easily -- it exists only to
8549 // reduce the compile time impact of this optimization.
8550 return false;
8551
8552 const SCEVAddExpr *AddLHS = dyn_cast<SCEVAddExpr>(LHS);
8553 if (!AddLHS || AddLHS->getOperand(1) != FoundLHS ||
8554 !isa<SCEVConstant>(AddLHS->getOperand(0)))
8555 return false;
8556
8557 APInt ConstFoundRHS = cast<SCEVConstant>(FoundRHS)->getAPInt();
8558
8559 // `FoundLHSRange` is the range we know `FoundLHS` to be in by virtue of the
8560 // antecedent "`FoundLHS` `Pred` `FoundRHS`".
8561 ConstantRange FoundLHSRange =
8562 ConstantRange::makeAllowedICmpRegion(Pred, ConstFoundRHS);
8563
8564 // Since `LHS` is `FoundLHS` + `AddLHS->getOperand(0)`, we can compute a range
8565 // for `LHS`:
8566 APInt Addend = cast<SCEVConstant>(AddLHS->getOperand(0))->getAPInt();
8567 ConstantRange LHSRange = FoundLHSRange.add(ConstantRange(Addend));
8568
8569 // We can also compute the range of values for `LHS` that satisfy the
8570 // consequent, "`LHS` `Pred` `RHS`":
8571 APInt ConstRHS = cast<SCEVConstant>(RHS)->getAPInt();
8572 ConstantRange SatisfyingLHSRange =
8573 ConstantRange::makeSatisfyingICmpRegion(Pred, ConstRHS);
8574
8575 // The antecedent implies the consequent if every value of `LHS` that
8576 // satisfies the antecedent also satisfies the consequent.
8577 return SatisfyingLHSRange.contains(LHSRange);
8578}
8579
8580// Verify if an linear IV with positive stride can overflow when in a
8581// less-than comparison, knowing the invariant term of the comparison, the
8582// stride and the knowledge of NSW/NUW flags on the recurrence.
8583bool ScalarEvolution::doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
8584 bool IsSigned, bool NoWrap) {
8585 if (NoWrap) return false;
8586
8587 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
8588 const SCEV *One = getOne(Stride->getType());
8589
8590 if (IsSigned) {
8591 APInt MaxRHS = getSignedRange(RHS).getSignedMax();
8592 APInt MaxValue = APInt::getSignedMaxValue(BitWidth);
8593 APInt MaxStrideMinusOne = getSignedRange(getMinusSCEV(Stride, One))
8594 .getSignedMax();
8595
8596 // SMaxRHS + SMaxStrideMinusOne > SMaxValue => overflow!
8597 return (MaxValue - MaxStrideMinusOne).slt(MaxRHS);
8598 }
8599
8600 APInt MaxRHS = getUnsignedRange(RHS).getUnsignedMax();
8601 APInt MaxValue = APInt::getMaxValue(BitWidth);
8602 APInt MaxStrideMinusOne = getUnsignedRange(getMinusSCEV(Stride, One))
8603 .getUnsignedMax();
8604
8605 // UMaxRHS + UMaxStrideMinusOne > UMaxValue => overflow!
8606 return (MaxValue - MaxStrideMinusOne).ult(MaxRHS);
8607}
8608
8609// Verify if an linear IV with negative stride can overflow when in a
8610// greater-than comparison, knowing the invariant term of the comparison,
8611// the stride and the knowledge of NSW/NUW flags on the recurrence.
8612bool ScalarEvolution::doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
8613 bool IsSigned, bool NoWrap) {
8614 if (NoWrap) return false;
8615
8616 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
8617 const SCEV *One = getOne(Stride->getType());
8618
8619 if (IsSigned) {
8620 APInt MinRHS = getSignedRange(RHS).getSignedMin();
8621 APInt MinValue = APInt::getSignedMinValue(BitWidth);
8622 APInt MaxStrideMinusOne = getSignedRange(getMinusSCEV(Stride, One))
8623 .getSignedMax();
8624
8625 // SMinRHS - SMaxStrideMinusOne < SMinValue => overflow!
8626 return (MinValue + MaxStrideMinusOne).sgt(MinRHS);
8627 }
8628
8629 APInt MinRHS = getUnsignedRange(RHS).getUnsignedMin();
8630 APInt MinValue = APInt::getMinValue(BitWidth);
8631 APInt MaxStrideMinusOne = getUnsignedRange(getMinusSCEV(Stride, One))
8632 .getUnsignedMax();
8633
8634 // UMinRHS - UMaxStrideMinusOne < UMinValue => overflow!
8635 return (MinValue + MaxStrideMinusOne).ugt(MinRHS);
8636}
8637
8638// Compute the backedge taken count knowing the interval difference, the
8639// stride and presence of the equality in the comparison.
8640const SCEV *ScalarEvolution::computeBECount(const SCEV *Delta, const SCEV *Step,
8641 bool Equality) {
8642 const SCEV *One = getOne(Step->getType());
8643 Delta = Equality ? getAddExpr(Delta, Step)
8644 : getAddExpr(Delta, getMinusSCEV(Step, One));
8645 return getUDivExpr(Delta, Step);
8646}
8647
8648/// HowManyLessThans - Return the number of times a backedge containing the
8649/// specified less-than comparison will execute. If not computable, return
8650/// CouldNotCompute.
8651///
8652/// @param ControlsExit is true when the LHS < RHS condition directly controls
8653/// the branch (loops exits only if condition is true). In this case, we can use
8654/// NoWrapFlags to skip overflow checks.
8655ScalarEvolution::ExitLimit
8656ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
8657 const Loop *L, bool IsSigned,
8658 bool ControlsExit, bool AllowPredicates) {
8659 SCEVUnionPredicate P;
8660 // We handle only IV < Invariant
8661 if (!isLoopInvariant(RHS, L))
8662 return getCouldNotCompute();
8663
8664 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
8665 if (!IV && AllowPredicates)
8666 // Try to make this an AddRec using runtime tests, in the first X
8667 // iterations of this loop, where X is the SCEV expression found by the
8668 // algorithm below.
8669 IV = convertSCEVToAddRecWithPredicates(LHS, L, P);
8670
8671 // Avoid weird loops
8672 if (!IV || IV->getLoop() != L || !IV->isAffine())
8673 return getCouldNotCompute();
8674
8675 bool NoWrap = ControlsExit &&
8676 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
8677
8678 const SCEV *Stride = IV->getStepRecurrence(*this);
8679
8680 // Avoid negative or zero stride values
8681 if (!isKnownPositive(Stride))
8682 return getCouldNotCompute();
8683
8684 // Avoid proven overflow cases: this will ensure that the backedge taken count
8685 // will not generate any unsigned overflow. Relaxed no-overflow conditions
8686 // exploit NoWrapFlags, allowing to optimize in presence of undefined
8687 // behaviors like the case of C language.
8688 if (!Stride->isOne() && doesIVOverflowOnLT(RHS, Stride, IsSigned, NoWrap))
8689 return getCouldNotCompute();
8690
8691 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SLT
8692 : ICmpInst::ICMP_ULT;
8693 const SCEV *Start = IV->getStart();
8694 const SCEV *End = RHS;
8695 if (!isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS)) {
8696 const SCEV *Diff = getMinusSCEV(RHS, Start);
8697 // If we have NoWrap set, then we can assume that the increment won't
8698 // overflow, in which case if RHS - Start is a constant, we don't need to
8699 // do a max operation since we can just figure it out statically
8700 if (NoWrap && isa<SCEVConstant>(Diff)) {
8701 APInt D = dyn_cast<const SCEVConstant>(Diff)->getAPInt();
8702 if (D.isNegative())
8703 End = Start;
8704 } else
8705 End = IsSigned ? getSMaxExpr(RHS, Start)
8706 : getUMaxExpr(RHS, Start);
8707 }
8708
8709 const SCEV *BECount = computeBECount(getMinusSCEV(End, Start), Stride, false);
8710
8711 APInt MinStart = IsSigned ? getSignedRange(Start).getSignedMin()
8712 : getUnsignedRange(Start).getUnsignedMin();
8713
8714 APInt MinStride = IsSigned ? getSignedRange(Stride).getSignedMin()
8715 : getUnsignedRange(Stride).getUnsignedMin();
8716
8717 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
8718 APInt Limit = IsSigned ? APInt::getSignedMaxValue(BitWidth) - (MinStride - 1)
8719 : APInt::getMaxValue(BitWidth) - (MinStride - 1);
8720
8721 // Although End can be a MAX expression we estimate MaxEnd considering only
8722 // the case End = RHS. This is safe because in the other case (End - Start)
8723 // is zero, leading to a zero maximum backedge taken count.
8724 APInt MaxEnd =
8725 IsSigned ? APIntOps::smin(getSignedRange(RHS).getSignedMax(), Limit)
8726 : APIntOps::umin(getUnsignedRange(RHS).getUnsignedMax(), Limit);
8727
8728 const SCEV *MaxBECount;
8729 if (isa<SCEVConstant>(BECount))
8730 MaxBECount = BECount;
8731 else
8732 MaxBECount = computeBECount(getConstant(MaxEnd - MinStart),
8733 getConstant(MinStride), false);
8734
8735 if (isa<SCEVCouldNotCompute>(MaxBECount))
8736 MaxBECount = BECount;
8737
8738 return ExitLimit(BECount, MaxBECount, P);
8739}
8740
8741ScalarEvolution::ExitLimit
8742ScalarEvolution::HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
8743 const Loop *L, bool IsSigned,
8744 bool ControlsExit, bool AllowPredicates) {
8745 SCEVUnionPredicate P;
8746 // We handle only IV > Invariant
8747 if (!isLoopInvariant(RHS, L))
8748 return getCouldNotCompute();
8749
8750 const SCEVAddRecExpr *IV = dyn_cast<SCEVAddRecExpr>(LHS);
8751 if (!IV && AllowPredicates)
8752 // Try to make this an AddRec using runtime tests, in the first X
8753 // iterations of this loop, where X is the SCEV expression found by the
8754 // algorithm below.
8755 IV = convertSCEVToAddRecWithPredicates(LHS, L, P);
8756
8757 // Avoid weird loops
8758 if (!IV || IV->getLoop() != L || !IV->isAffine())
8759 return getCouldNotCompute();
8760
8761 bool NoWrap = ControlsExit &&
8762 IV->getNoWrapFlags(IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW);
8763
8764 const SCEV *Stride = getNegativeSCEV(IV->getStepRecurrence(*this));
8765
8766 // Avoid negative or zero stride values
8767 if (!isKnownPositive(Stride))
8768 return getCouldNotCompute();
8769
8770 // Avoid proven overflow cases: this will ensure that the backedge taken count
8771 // will not generate any unsigned overflow. Relaxed no-overflow conditions
8772 // exploit NoWrapFlags, allowing to optimize in presence of undefined
8773 // behaviors like the case of C language.
8774 if (!Stride->isOne() && doesIVOverflowOnGT(RHS, Stride, IsSigned, NoWrap))
8775 return getCouldNotCompute();
8776
8777 ICmpInst::Predicate Cond = IsSigned ? ICmpInst::ICMP_SGT
8778 : ICmpInst::ICMP_UGT;
8779
8780 const SCEV *Start = IV->getStart();
8781 const SCEV *End = RHS;
8782 if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) {
8783 const SCEV *Diff = getMinusSCEV(RHS, Start);
8784 // If we have NoWrap set, then we can assume that the increment won't
8785 // overflow, in which case if RHS - Start is a constant, we don't need to
8786 // do a max operation since we can just figure it out statically
8787 if (NoWrap && isa<SCEVConstant>(Diff)) {
8788 APInt D = dyn_cast<const SCEVConstant>(Diff)->getAPInt();
8789 if (!D.isNegative())
8790 End = Start;
8791 } else
8792 End = IsSigned ? getSMinExpr(RHS, Start)
8793 : getUMinExpr(RHS, Start);
8794 }
8795
8796 const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
8797
8798 APInt MaxStart = IsSigned ? getSignedRange(Start).getSignedMax()
8799 : getUnsignedRange(Start).getUnsignedMax();
8800
8801 APInt MinStride = IsSigned ? getSignedRange(Stride).getSignedMin()
8802 : getUnsignedRange(Stride).getUnsignedMin();
8803
8804 unsigned BitWidth = getTypeSizeInBits(LHS->getType());
8805 APInt Limit = IsSigned ? APInt::getSignedMinValue(BitWidth) + (MinStride - 1)
8806 : APInt::getMinValue(BitWidth) + (MinStride - 1);
8807
8808 // Although End can be a MIN expression we estimate MinEnd considering only
8809 // the case End = RHS. This is safe because in the other case (Start - End)
8810 // is zero, leading to a zero maximum backedge taken count.
8811 APInt MinEnd =
8812 IsSigned ? APIntOps::smax(getSignedRange(RHS).getSignedMin(), Limit)
8813 : APIntOps::umax(getUnsignedRange(RHS).getUnsignedMin(), Limit);
8814
8815
8816 const SCEV *MaxBECount = getCouldNotCompute();
Value stored to 'MaxBECount' during its initialization is never read
8817 if (isa<SCEVConstant>(BECount))
8818 MaxBECount = BECount;
8819 else
8820 MaxBECount = computeBECount(getConstant(MaxStart - MinEnd),
8821 getConstant(MinStride), false);
8822
8823 if (isa<SCEVCouldNotCompute>(MaxBECount))
8824 MaxBECount = BECount;
8825
8826 return ExitLimit(BECount, MaxBECount, P);
8827}
8828
8829/// getNumIterationsInRange - Return the number of iterations of this loop that
8830/// produce values in the specified constant range. Another way of looking at
8831/// this is that it returns the first iteration number where the value is not in
8832/// the condition, thus computing the exit count. If the iteration count can't
8833/// be computed, an instance of SCEVCouldNotCompute is returned.
8834const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range,
8835 ScalarEvolution &SE) const {
8836 if (Range.isFullSet()) // Infinite loop.
8837 return SE.getCouldNotCompute();
8838
8839 // If the start is a non-zero constant, shift the range to simplify things.
8840 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
8841 if (!SC->getValue()->isZero()) {
8842 SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
8843 Operands[0] = SE.getZero(SC->getType());
8844 const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop(),
8845 getNoWrapFlags(FlagNW));
8846 if (const auto *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
8847 return ShiftedAddRec->getNumIterationsInRange(
8848 Range.subtract(SC->getAPInt()), SE);
8849 // This is strange and shouldn't happen.
8850 return SE.getCouldNotCompute();
8851 }
8852
8853 // The only time we can solve this is when we have all constant indices.
8854 // Otherwise, we cannot determine the overflow conditions.
8855 if (any_of(operands(), [](const SCEV *Op) { return !isa<SCEVConstant>(Op); }))
8856 return SE.getCouldNotCompute();
8857
8858 // Okay at this point we know that all elements of the chrec are constants and
8859 // that the start element is zero.
8860
8861 // First check to see if the range contains zero. If not, the first
8862 // iteration exits.
8863 unsigned BitWidth = SE.getTypeSizeInBits(getType());
8864 if (!Range.contains(APInt(BitWidth, 0)))
8865 return SE.getZero(getType());
8866
8867 if (isAffine()) {
8868 // If this is an affine expression then we have this situation:
8869 // Solve {0,+,A} in Range === Ax in Range
8870
8871 // We know that zero is in the range. If A is positive then we know that
8872 // the upper value of the range must be the first possible exit value.
8873 // If A is negative then the lower of the range is the last possible loop
8874 // value. Also note that we already checked for a full range.
8875 APInt One(BitWidth,1);
8876 APInt A = cast<SCEVConstant>(getOperand(1))->getAPInt();
8877 APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower();
8878
8879 // The exit value should be (End+A)/A.
8880 APInt ExitVal = (End + A).udiv(A);
8881 ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
8882
8883 // Evaluate at the exit value. If we really did fall out of the valid
8884 // range, then we computed our trip count, otherwise wrap around or other
8885 // things must have happened.
8886 ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
8887 if (Range.contains(Val->getValue()))
8888 return SE.getCouldNotCompute(); // Something strange happened
8889
8890 // Ensure that the previous value is in the range. This is a sanity check.
8891 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8894, __PRETTY_FUNCTION__))
8892 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8894, __PRETTY_FUNCTION__))
8893 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8894, __PRETTY_FUNCTION__))
8894 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 8894, __PRETTY_FUNCTION__))
;
8895 return SE.getConstant(ExitValue);
8896 } else if (isQuadratic()) {
8897 // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of the
8898 // quadratic equation to solve it. To do this, we must frame our problem in
8899 // terms of figuring out when zero is crossed, instead of when
8900 // Range.getUpper() is crossed.
8901 SmallVector<const SCEV *, 4> NewOps(op_begin(), op_end());
8902 NewOps[0] = SE.getNegativeSCEV(SE.getConstant(Range.getUpper()));
8903 const SCEV *NewAddRec = SE.getAddRecExpr(NewOps, getLoop(),
8904 // getNoWrapFlags(FlagNW)
8905 FlagAnyWrap);
8906
8907 // Next, solve the constructed addrec
8908 auto Roots = SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE);
8909 const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
8910 const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
8911 if (R1) {
8912 // Pick the smallest positive root value.
8913 if (ConstantInt *CB = dyn_cast<ConstantInt>(ConstantExpr::getICmp(
8914 ICmpInst::ICMP_ULT, R1->getValue(), R2->getValue()))) {
8915 if (!CB->getZExtValue())
8916 std::swap(R1, R2); // R1 is the minimum root now.
8917
8918 // Make sure the root is not off by one. The returned iteration should
8919 // not be in the range, but the previous one should be. When solving
8920 // for "X*X < 5", for example, we should not return a root of 2.
8921 ConstantInt *R1Val = EvaluateConstantChrecAtConstant(this,
8922 R1->getValue(),
8923 SE);
8924 if (Range.contains(R1Val->getValue())) {
8925 // The next iteration must be out of the range...
8926 ConstantInt *NextVal =
8927 ConstantInt::get(SE.getContext(), R1->getAPInt() + 1);
8928
8929 R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
8930 if (!Range.contains(R1Val->getValue()))
8931 return SE.getConstant(NextVal);
8932 return SE.getCouldNotCompute(); // Something strange happened
8933 }
8934
8935 // If R1 was not in the range, then it is a good return value. Make
8936 // sure that R1-1 WAS in the range though, just in case.
8937 ConstantInt *NextVal =
8938 ConstantInt::get(SE.getContext(), R1->getAPInt() - 1);
8939 R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
8940 if (Range.contains(R1Val->getValue()))
8941 return R1;
8942 return SE.getCouldNotCompute(); // Something strange happened
8943 }
8944 }
8945 }
8946
8947 return SE.getCouldNotCompute();
8948}
8949
8950namespace {
8951struct FindUndefs {
8952 bool Found;
8953 FindUndefs() : Found(false) {}
8954
8955 bool follow(const SCEV *S) {
8956 if (const SCEVUnknown *C = dyn_cast<SCEVUnknown>(S)) {
8957 if (isa<UndefValue>(C->getValue()))
8958 Found = true;
8959 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
8960 if (isa<UndefValue>(C->getValue()))
8961 Found = true;
8962 }
8963
8964 // Keep looking if we haven't found it yet.
8965 return !Found;
8966 }
8967 bool isDone() const {
8968 // Stop recursion if we have found an undef.
8969 return Found;
8970 }
8971};
8972}
8973
8974// Return true when S contains at least an undef value.
8975static inline bool
8976containsUndefs(const SCEV *S) {
8977 FindUndefs F;
8978 SCEVTraversal<FindUndefs> ST(F);
8979 ST.visitAll(S);
8980
8981 return F.Found;
8982}
8983
8984namespace {
8985// Collect all steps of SCEV expressions.
8986struct SCEVCollectStrides {
8987 ScalarEvolution &SE;
8988 SmallVectorImpl<const SCEV *> &Strides;
8989
8990 SCEVCollectStrides(ScalarEvolution &SE, SmallVectorImpl<const SCEV *> &S)
8991 : SE(SE), Strides(S) {}
8992
8993 bool follow(const SCEV *S) {
8994 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
8995 Strides.push_back(AR->getStepRecurrence(SE));
8996 return true;
8997 }
8998 bool isDone() const { return false; }
8999};
9000
9001// Collect all SCEVUnknown and SCEVMulExpr expressions.
9002struct SCEVCollectTerms {
9003 SmallVectorImpl<const SCEV *> &Terms;
9004
9005 SCEVCollectTerms(SmallVectorImpl<const SCEV *> &T)
9006 : Terms(T) {}
9007
9008 bool follow(const SCEV *S) {
9009 if (isa<SCEVUnknown>(S) || isa<SCEVMulExpr>(S)) {
9010 if (!containsUndefs(S))
9011 Terms.push_back(S);
9012
9013 // Stop recursion: once we collected a term, do not walk its operands.
9014 return false;
9015 }
9016
9017 // Keep looking.
9018 return true;
9019 }
9020 bool isDone() const { return false; }
9021};
9022
9023// Check if a SCEV contains an AddRecExpr.
9024struct SCEVHasAddRec {
9025 bool &ContainsAddRec;
9026
9027 SCEVHasAddRec(bool &ContainsAddRec) : ContainsAddRec(ContainsAddRec) {
9028 ContainsAddRec = false;
9029 }
9030
9031 bool follow(const SCEV *S) {
9032 if (isa<SCEVAddRecExpr>(S)) {
9033 ContainsAddRec = true;
9034
9035 // Stop recursion: once we collected a term, do not walk its operands.
9036 return false;
9037 }
9038
9039 // Keep looking.
9040 return true;
9041 }
9042 bool isDone() const { return false; }
9043};
9044
9045// Find factors that are multiplied with an expression that (possibly as a
9046// subexpression) contains an AddRecExpr. In the expression:
9047//
9048// 8 * (100 + %p * %q * (%a + {0, +, 1}_loop))
9049//
9050// "%p * %q" are factors multiplied by the expression "(%a + {0, +, 1}_loop)"
9051// that contains the AddRec {0, +, 1}_loop. %p * %q are likely to be array size
9052// parameters as they form a product with an induction variable.
9053//
9054// This collector expects all array size parameters to be in the same MulExpr.
9055// It might be necessary to later add support for collecting parameters that are
9056// spread over different nested MulExpr.
9057struct SCEVCollectAddRecMultiplies {
9058 SmallVectorImpl<const SCEV *> &Terms;
9059 ScalarEvolution &SE;
9060
9061 SCEVCollectAddRecMultiplies(SmallVectorImpl<const SCEV *> &T, ScalarEvolution &SE)
9062 : Terms(T), SE(SE) {}
9063
9064 bool follow(const SCEV *S) {
9065 if (auto *Mul = dyn_cast<SCEVMulExpr>(S)) {
9066 bool HasAddRec = false;
9067 SmallVector<const SCEV *, 0> Operands;
9068 for (auto Op : Mul->operands()) {
9069 if (isa<SCEVUnknown>(Op)) {
9070 Operands.push_back(Op);
9071 } else {
9072 bool ContainsAddRec;
9073 SCEVHasAddRec ContiansAddRec(ContainsAddRec);
9074 visitAll(Op, ContiansAddRec);
9075 HasAddRec |= ContainsAddRec;
9076 }
9077 }
9078 if (Operands.size() == 0)
9079 return true;
9080
9081 if (!HasAddRec)
9082 return false;
9083
9084 Terms.push_back(SE.getMulExpr(Operands));
9085 // Stop recursion: once we collected a term, do not walk its operands.
9086 return false;
9087 }
9088
9089 // Keep looking.
9090 return true;
9091 }
9092 bool isDone() const { return false; }
9093};
9094}
9095
9096/// Find parametric terms in this SCEVAddRecExpr. We first for parameters in
9097/// two places:
9098/// 1) The strides of AddRec expressions.
9099/// 2) Unknowns that are multiplied with AddRec expressions.
9100void ScalarEvolution::collectParametricTerms(const SCEV *Expr,
9101 SmallVectorImpl<const SCEV *> &Terms) {
9102 SmallVector<const SCEV *, 4> Strides;
9103 SCEVCollectStrides StrideCollector(*this, Strides);
9104 visitAll(Expr, StrideCollector);
9105
9106 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9107 dbgs() << "Strides:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9108 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)
9109 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
9110 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Strides:\n"; for (
const SCEV *S : Strides) dbgs() << *S << "\n"; };
} } while (0)
;
9111
9112 for (const SCEV *S : Strides) {
9113 SCEVCollectTerms TermCollector(Terms);
9114 visitAll(S, TermCollector);
9115 }
9116
9117 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9118 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9119 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)
9120 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9121 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
;
9122
9123 SCEVCollectAddRecMultiplies MulCollector(Terms, *this);
9124 visitAll(Expr, MulCollector);
9125}
9126
9127static bool findArrayDimensionsRec(ScalarEvolution &SE,
9128 SmallVectorImpl<const SCEV *> &Terms,
9129 SmallVectorImpl<const SCEV *> &Sizes) {
9130 int Last = Terms.size() - 1;
9131 const SCEV *Step = Terms[Last];
9132
9133 // End of recursion.
9134 if (Last == 0) {
9135 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Step)) {
9136 SmallVector<const SCEV *, 2> Qs;
9137 for (const SCEV *Op : M->operands())
9138 if (!isa<SCEVConstant>(Op))
9139 Qs.push_back(Op);
9140
9141 Step = SE.getMulExpr(Qs);
9142 }
9143
9144 Sizes.push_back(Step);
9145 return true;
9146 }
9147
9148 for (const SCEV *&Term : Terms) {
9149 // Normalize the terms before the next call to findArrayDimensionsRec.
9150 const SCEV *Q, *R;
9151 SCEVDivision::divide(SE, Term, Step, &Q, &R);
9152
9153 // Bail out when GCD does not evenly divide one of the terms.
9154 if (!R->isZero())
9155 return false;
9156
9157 Term = Q;
9158 }
9159
9160 // Remove all SCEVConstants.
9161 Terms.erase(std::remove_if(Terms.begin(), Terms.end(), [](const SCEV *E) {
9162 return isa<SCEVConstant>(E);
9163 }),
9164 Terms.end());
9165
9166 if (Terms.size() > 0)
9167 if (!findArrayDimensionsRec(SE, Terms, Sizes))
9168 return false;
9169
9170 Sizes.push_back(Step);
9171 return true;
9172}
9173
9174// Returns true when S contains at least a SCEVUnknown parameter.
9175static inline bool
9176containsParameters(const SCEV *S) {
9177 struct FindParameter {
9178 bool FoundParameter;
9179 FindParameter() : FoundParameter(false) {}
9180
9181 bool follow(const SCEV *S) {
9182 if (isa<SCEVUnknown>(S)) {
9183 FoundParameter = true;
9184 // Stop recursion: we found a parameter.
9185 return false;
9186 }
9187 // Keep looking.
9188 return true;
9189 }
9190 bool isDone() const {
9191 // Stop recursion if we have found a parameter.
9192 return FoundParameter;
9193 }
9194 };
9195
9196 FindParameter F;
9197 SCEVTraversal<FindParameter> ST(F);
9198 ST.visitAll(S);
9199
9200 return F.FoundParameter;
9201}
9202
9203// Returns true when one of the SCEVs of Terms contains a SCEVUnknown parameter.
9204static inline bool
9205containsParameters(SmallVectorImpl<const SCEV *> &Terms) {
9206 for (const SCEV *T : Terms)
9207 if (containsParameters(T))
9208 return true;
9209 return false;
9210}
9211
9212// Return the number of product terms in S.
9213static inline int numberOfTerms(const SCEV *S) {
9214 if (const SCEVMulExpr *Expr = dyn_cast<SCEVMulExpr>(S))
9215 return Expr->getNumOperands();
9216 return 1;
9217}
9218
9219static const SCEV *removeConstantFactors(ScalarEvolution &SE, const SCEV *T) {
9220 if (isa<SCEVConstant>(T))
9221 return nullptr;
9222
9223 if (isa<SCEVUnknown>(T))
9224 return T;
9225
9226 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(T)) {
9227 SmallVector<const SCEV *, 2> Factors;
9228 for (const SCEV *Op : M->operands())
9229 if (!isa<SCEVConstant>(Op))
9230 Factors.push_back(Op);
9231
9232 return SE.getMulExpr(Factors);
9233 }
9234
9235 return T;
9236}
9237
9238/// Return the size of an element read or written by Inst.
9239const SCEV *ScalarEvolution::getElementSize(Instruction *Inst) {
9240 Type *Ty;
9241 if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
9242 Ty = Store->getValueOperand()->getType();
9243 else if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
9244 Ty = Load->getType();
9245 else
9246 return nullptr;
9247
9248 Type *ETy = getEffectiveSCEVType(PointerType::getUnqual(Ty));
9249 return getSizeOfExpr(ETy, Ty);
9250}
9251
9252/// Second step of delinearization: compute the array dimensions Sizes from the
9253/// set of Terms extracted from the memory access function of this SCEVAddRec.
9254void ScalarEvolution::findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
9255 SmallVectorImpl<const SCEV *> &Sizes,
9256 const SCEV *ElementSize) const {
9257
9258 if (Terms.size() < 1 || !ElementSize)
9259 return;
9260
9261 // Early return when Terms do not contain parameters: we do not delinearize
9262 // non parametric SCEVs.
9263 if (!containsParameters(Terms))
9264 return;
9265
9266 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9267 dbgs() << "Terms:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9268 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)
9269 dbgs() << *T << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
9270 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms:\n"; for (const
SCEV *T : Terms) dbgs() << *T << "\n"; }; } } while
(0)
;
9271
9272 // Remove duplicates.
9273 std::sort(Terms.begin(), Terms.end());
9274 Terms.erase(std::unique(Terms.begin(), Terms.end()), Terms.end());
9275
9276 // Put larger terms first.
9277 std::sort(Terms.begin(), Terms.end(), [](const SCEV *LHS, const SCEV *RHS) {
9278 return numberOfTerms(LHS) > numberOfTerms(RHS);
9279 });
9280
9281 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
9282
9283 // Try to divide all terms by the element size. If term is not divisible by
9284 // element size, proceed with the original term.
9285 for (const SCEV *&Term : Terms) {
9286 const SCEV *Q, *R;
9287 SCEVDivision::divide(SE, Term, ElementSize, &Q, &R);
9288 if (!Q->isZero())
9289 Term = Q;
9290 }
9291
9292 SmallVector<const SCEV *, 4> NewTerms;
9293
9294 // Remove constant factors.
9295 for (const SCEV *T : Terms)
9296 if (const SCEV *NewT = removeConstantFactors(SE, T))
9297 NewTerms.push_back(NewT);
9298
9299 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0)
9300 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)
9301 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)
9302 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)
9303 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Terms after sorting:\n"
; for (const SCEV *T : NewTerms) dbgs() << *T << "\n"
; }; } } while (0)
;
9304
9305 if (NewTerms.empty() ||
9306 !findArrayDimensionsRec(SE, NewTerms, Sizes)) {
9307 Sizes.clear();
9308 return;
9309 }
9310
9311 // The last element to be pushed into Sizes is the size of an element.
9312 Sizes.push_back(ElementSize);
9313
9314 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9315 dbgs() << "Sizes:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9316 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)
9317 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
9318 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Sizes:\n"; for (const
SCEV *S : Sizes) dbgs() << *S << "\n"; }; } } while
(0)
;
9319}
9320
9321/// Third step of delinearization: compute the access functions for the
9322/// Subscripts based on the dimensions in Sizes.
9323void ScalarEvolution::computeAccessFunctions(
9324 const SCEV *Expr, SmallVectorImpl<const SCEV *> &Subscripts,
9325 SmallVectorImpl<const SCEV *> &Sizes) {
9326
9327 // Early exit in case this SCEV is not an affine multivariate function.
9328 if (Sizes.empty())
9329 return;
9330
9331 if (auto *AR = dyn_cast<SCEVAddRecExpr>(Expr))
9332 if (!AR->isAffine())
9333 return;
9334
9335 const SCEV *Res = Expr;
9336 int Last = Sizes.size() - 1;
9337 for (int i = Last; i >= 0; i--) {
9338 const SCEV *Q, *R;
9339 SCEVDivision::divide(*this, Res, Sizes[i], &Q, &R);
9340
9341 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)
9342 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)
9343 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)
9344 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)
9345 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)
9346 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)
9347 })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)
;
9348
9349 Res = Q;
9350
9351 // Do not record the last subscript corresponding to the size of elements in
9352 // the array.
9353 if (i == Last) {
9354
9355 // Bail out if the remainder is too complex.
9356 if (isa<SCEVAddRecExpr>(R)) {
9357 Subscripts.clear();
9358 Sizes.clear();
9359 return;
9360 }
9361
9362 continue;
9363 }
9364
9365 // Record the access function for the current subscript.
9366 Subscripts.push_back(R);
9367 }
9368
9369 // Also push in last position the remainder of the last division: it will be
9370 // the access function of the innermost dimension.
9371 Subscripts.push_back(Res);
9372
9373 std::reverse(Subscripts.begin(), Subscripts.end());
9374
9375 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9376 dbgs() << "Subscripts:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9377 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)
9378 dbgs() << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
9379 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { { dbgs() << "Subscripts:\n"; for
(const SCEV *S : Subscripts) dbgs() << *S << "\n"
; }; } } while (0)
;
9380}
9381
9382/// Splits the SCEV into two vectors of SCEVs representing the subscripts and
9383/// sizes of an array access. Returns the remainder of the delinearization that
9384/// is the offset start of the array. The SCEV->delinearize algorithm computes
9385/// the multiples of SCEV coefficients: that is a pattern matching of sub
9386/// expressions in the stride and base of a SCEV corresponding to the
9387/// computation of a GCD (greatest common divisor) of base and stride. When
9388/// SCEV->delinearize fails, it returns the SCEV unchanged.
9389///
9390/// For example: when analyzing the memory access A[i][j][k] in this loop nest
9391///
9392/// void foo(long n, long m, long o, double A[n][m][o]) {
9393///
9394/// for (long i = 0; i < n; i++)
9395/// for (long j = 0; j < m; j++)
9396/// for (long k = 0; k < o; k++)
9397/// A[i][j][k] = 1.0;
9398/// }
9399///
9400/// the delinearization input is the following AddRec SCEV:
9401///
9402/// AddRec: {{{%A,+,(8 * %m * %o)}<%for.i>,+,(8 * %o)}<%for.j>,+,8}<%for.k>
9403///
9404/// From this SCEV, we are able to say that the base offset of the access is %A
9405/// because it appears as an offset that does not divide any of the strides in
9406/// the loops:
9407///
9408/// CHECK: Base offset: %A
9409///
9410/// and then SCEV->delinearize determines the size of some of the dimensions of
9411/// the array as these are the multiples by which the strides are happening:
9412///
9413/// CHECK: ArrayDecl[UnknownSize][%m][%o] with elements of sizeof(double) bytes.
9414///
9415/// Note that the outermost dimension remains of UnknownSize because there are
9416/// no strides that would help identifying the size of the last dimension: when
9417/// the array has been statically allocated, one could compute the size of that
9418/// dimension by dividing the overall size of the array by the size of the known
9419/// dimensions: %m * %o * 8.
9420///
9421/// Finally delinearize provides the access functions for the array reference
9422/// that does correspond to A[i][j][k] of the above C testcase:
9423///
9424/// CHECK: ArrayRef[{0,+,1}<%for.i>][{0,+,1}<%for.j>][{0,+,1}<%for.k>]
9425///
9426/// The testcases are checking the output of a function pass:
9427/// DelinearizationPass that walks through all loads and stores of a function
9428/// asking for the SCEV of the memory access with respect to all enclosing
9429/// loops, calling SCEV->delinearize on that and printing the results.
9430
9431void ScalarEvolution::delinearize(const SCEV *Expr,
9432 SmallVectorImpl<const SCEV *> &Subscripts,
9433 SmallVectorImpl<const SCEV *> &Sizes,
9434 const SCEV *ElementSize) {
9435 // First step: collect parametric terms.
9436 SmallVector<const SCEV *, 4> Terms;
9437 collectParametricTerms(Expr, Terms);
9438
9439 if (Terms.empty())
9440 return;
9441
9442 // Second step: find subscript sizes.
9443 findArrayDimensions(Terms, Sizes, ElementSize);
9444
9445 if (Sizes.empty())
9446 return;
9447
9448 // Third step: compute the access functions for each subscript.
9449 computeAccessFunctions(Expr, Subscripts, Sizes);
9450
9451 if (Subscripts.empty())
9452 return;
9453
9454 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)
9455 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)
9456 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)
9457 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)
9458 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)
9459
9460 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)
9461 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)
9462 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)
9463 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)
9464 })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)
;
9465}
9466
9467//===----------------------------------------------------------------------===//
9468// SCEVCallbackVH Class Implementation
9469//===----------------------------------------------------------------------===//
9470
9471void ScalarEvolution::SCEVCallbackVH::deleted() {
9472 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9472, __PRETTY_FUNCTION__))
;
9473 if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
9474 SE->ConstantEvolutionLoopExitValue.erase(PN);
9475 SE->eraseValueFromMap(getValPtr());
9476 // this now dangles!
9477}
9478
9479void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
9480 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9480, __PRETTY_FUNCTION__))
;
9481
9482 // Forget all the expressions associated with users of the old value,
9483 // so that future queries will recompute the expressions using the new
9484 // value.
9485 Value *Old = getValPtr();
9486 SmallVector<User *, 16> Worklist(Old->user_begin(), Old->user_end());
9487 SmallPtrSet<User *, 8> Visited;
9488 while (!Worklist.empty()) {
9489 User *U = Worklist.pop_back_val();
9490 // Deleting the Old value will cause this to dangle. Postpone
9491 // that until everything else is done.
9492 if (U == Old)
9493 continue;
9494 if (!Visited.insert(U).second)
9495 continue;
9496 if (PHINode *PN = dyn_cast<PHINode>(U))
9497 SE->ConstantEvolutionLoopExitValue.erase(PN);
9498 SE->eraseValueFromMap(U);
9499 Worklist.insert(Worklist.end(), U->user_begin(), U->user_end());
9500 }
9501 // Delete the Old value.
9502 if (PHINode *PN = dyn_cast<PHINode>(Old))
9503 SE->ConstantEvolutionLoopExitValue.erase(PN);
9504 SE->eraseValueFromMap(Old);
9505 // this now dangles!
9506}
9507
9508ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
9509 : CallbackVH(V), SE(se) {}
9510
9511//===----------------------------------------------------------------------===//
9512// ScalarEvolution Class Implementation
9513//===----------------------------------------------------------------------===//
9514
9515ScalarEvolution::ScalarEvolution(Function &F, TargetLibraryInfo &TLI,
9516 AssumptionCache &AC, DominatorTree &DT,
9517 LoopInfo &LI)
9518 : F(F), TLI(TLI), AC(AC), DT(DT), LI(LI),
9519 CouldNotCompute(new SCEVCouldNotCompute()),
9520 WalkingBEDominatingConds(false), ProvingSplitPredicate(false),
9521 ValuesAtScopes(64), LoopDispositions(64), BlockDispositions(64),
9522 FirstUnknown(nullptr) {
9523
9524 // To use guards for proving predicates, we need to scan every instruction in
9525 // relevant basic blocks, and not just terminators. Doing this is a waste of
9526 // time if the IR does not actually contain any calls to
9527 // @llvm.experimental.guard, so do a quick check and remember this beforehand.
9528 //
9529 // This pessimizes the case where a pass that preserves ScalarEvolution wants
9530 // to _add_ guards to the module when there weren't any before, and wants
9531 // ScalarEvolution to optimize based on those guards. For now we prefer to be
9532 // efficient in lieu of being smart in that rather obscure case.
9533
9534 auto *GuardDecl = F.getParent()->getFunction(
9535 Intrinsic::getName(Intrinsic::experimental_guard));
9536 HasGuards = GuardDecl && !GuardDecl->use_empty();
9537}
9538
9539ScalarEvolution::ScalarEvolution(ScalarEvolution &&Arg)
9540 : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT),
9541 LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)),
9542 ValueExprMap(std::move(Arg.ValueExprMap)),
9543 WalkingBEDominatingConds(false), ProvingSplitPredicate(false),
9544 BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
9545 PredicatedBackedgeTakenCounts(
9546 std::move(Arg.PredicatedBackedgeTakenCounts)),
9547 ConstantEvolutionLoopExitValue(
9548 std::move(Arg.ConstantEvolutionLoopExitValue)),
9549 ValuesAtScopes(std::move(Arg.ValuesAtScopes)),
9550 LoopDispositions(std::move(Arg.LoopDispositions)),
9551 BlockDispositions(std::move(Arg.BlockDispositions)),
9552 UnsignedRanges(std::move(Arg.UnsignedRanges)),
9553 SignedRanges(std::move(Arg.SignedRanges)),
9554 UniqueSCEVs(std::move(Arg.UniqueSCEVs)),
9555 UniquePreds(std::move(Arg.UniquePreds)),
9556 SCEVAllocator(std::move(Arg.SCEVAllocator)),
9557 FirstUnknown(Arg.FirstUnknown) {
9558 Arg.FirstUnknown = nullptr;
9559}
9560
9561ScalarEvolution::~ScalarEvolution() {
9562 // Iterate through all the SCEVUnknown instances and call their
9563 // destructors, so that they release their references to their values.
9564 for (SCEVUnknown *U = FirstUnknown; U;) {
9565 SCEVUnknown *Tmp = U;
9566 U = U->Next;
9567 Tmp->~SCEVUnknown();
9568 }
9569 FirstUnknown = nullptr;
9570
9571 ExprValueMap.clear();
9572 ValueExprMap.clear();
9573 HasRecMap.clear();
9574
9575 // Free any extra memory created for ExitNotTakenInfo in the unlikely event
9576 // that a loop had multiple computable exits.
9577 for (auto &BTCI : BackedgeTakenCounts)
9578 BTCI.second.clear();
9579 for (auto &BTCI : PredicatedBackedgeTakenCounts)
9580 BTCI.second.clear();
9581
9582 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9582, __PRETTY_FUNCTION__))
;
9583 assert(!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!")((!WalkingBEDominatingConds && "isLoopBackedgeGuardedByCond garbage!"
) ? static_cast<void> (0) : __assert_fail ("!WalkingBEDominatingConds && \"isLoopBackedgeGuardedByCond garbage!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9583, __PRETTY_FUNCTION__))
;
9584 assert(!ProvingSplitPredicate && "ProvingSplitPredicate garbage!")((!ProvingSplitPredicate && "ProvingSplitPredicate garbage!"
) ? static_cast<void> (0) : __assert_fail ("!ProvingSplitPredicate && \"ProvingSplitPredicate garbage!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9584, __PRETTY_FUNCTION__))
;
9585}
9586
9587bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
9588 return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
9589}
9590
9591static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
9592 const Loop *L) {
9593 // Print all inner loops first
9594 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
9595 PrintLoopInfo(OS, SE, *I);
9596
9597 OS << "Loop ";
9598 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9599 OS << ": ";
9600
9601 SmallVector<BasicBlock *, 8> ExitBlocks;
9602 L->getExitBlocks(ExitBlocks);
9603 if (ExitBlocks.size() != 1)
9604 OS << "<multiple exits> ";
9605
9606 if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
9607 OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L);
9608 } else {
9609 OS << "Unpredictable backedge-taken count. ";
9610 }
9611
9612 OS << "\n"
9613 "Loop ";
9614 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9615 OS << ": ";
9616
9617 if (!isa<SCEVCouldNotCompute>(SE->getMaxBackedgeTakenCount(L))) {
9618 OS << "max backedge-taken count is " << *SE->getMaxBackedgeTakenCount(L);
9619 } else {
9620 OS << "Unpredictable max backedge-taken count. ";
9621 }
9622
9623 OS << "\n"
9624 "Loop ";
9625 L->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9626 OS << ": ";
9627
9628 SCEVUnionPredicate Pred;
9629 auto PBT = SE->getPredicatedBackedgeTakenCount(L, Pred);
9630 if (!isa<SCEVCouldNotCompute>(PBT)) {
9631 OS << "Predicated backedge-taken count is " << *PBT << "\n";
9632 OS << " Predicates:\n";
9633 Pred.print(OS, 4);
9634 } else {
9635 OS << "Unpredictable predicated backedge-taken count. ";
9636 }
9637 OS << "\n";
9638}
9639
9640static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
9641 switch (LD) {
9642 case ScalarEvolution::LoopVariant:
9643 return "Variant";
9644 case ScalarEvolution::LoopInvariant:
9645 return "Invariant";
9646 case ScalarEvolution::LoopComputable:
9647 return "Computable";
9648 }
9649 llvm_unreachable("Unknown ScalarEvolution::LoopDisposition kind!")::llvm::llvm_unreachable_internal("Unknown ScalarEvolution::LoopDisposition kind!"
, "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9649)
;
9650}
9651
9652void ScalarEvolution::print(raw_ostream &OS) const {
9653 // ScalarEvolution's implementation of the print method is to print
9654 // out SCEV values of all instructions that are interesting. Doing
9655 // this potentially causes it to create new SCEV objects though,
9656 // which technically conflicts with the const qualifier. This isn't
9657 // observable from outside the class though, so casting away the
9658 // const isn't dangerous.
9659 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
9660
9661 OS << "Classifying expressions for: ";
9662 F.printAsOperand(OS, /*PrintType=*/false);
9663 OS << "\n";
9664 for (Instruction &I : instructions(F))
9665 if (isSCEVable(I.getType()) && !isa<CmpInst>(I)) {
9666 OS << I << '\n';
9667 OS << " --> ";
9668 const SCEV *SV = SE.getSCEV(&I);
9669 SV->print(OS);
9670 if (!isa<SCEVCouldNotCompute>(SV)) {
9671 OS << " U: ";
9672 SE.getUnsignedRange(SV).print(OS);
9673 OS << " S: ";
9674 SE.getSignedRange(SV).print(OS);
9675 }
9676
9677 const Loop *L = LI.getLoopFor(I.getParent());
9678
9679 const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
9680 if (AtUse != SV) {
9681 OS << " --> ";
9682 AtUse->print(OS);
9683 if (!isa<SCEVCouldNotCompute>(AtUse)) {
9684 OS << " U: ";
9685 SE.getUnsignedRange(AtUse).print(OS);
9686 OS << " S: ";
9687 SE.getSignedRange(AtUse).print(OS);
9688 }
9689 }
9690
9691 if (L) {
9692 OS << "\t\t" "Exits: ";
9693 const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
9694 if (!SE.isLoopInvariant(ExitValue, L)) {
9695 OS << "<<Unknown>>";
9696 } else {
9697 OS << *ExitValue;
9698 }
9699
9700 bool First = true;
9701 for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
9702 if (First) {
9703 OS << "\t\t" "LoopDispositions: { ";
9704 First = false;
9705 } else {
9706 OS << ", ";
9707 }
9708
9709 Iter->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9710 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
9711 }
9712
9713 for (auto *InnerL : depth_first(L)) {
9714 if (InnerL == L)
9715 continue;
9716 if (First) {
9717 OS << "\t\t" "LoopDispositions: { ";
9718 First = false;
9719 } else {
9720 OS << ", ";
9721 }
9722
9723 InnerL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
9724 OS << ": " << loopDispositionToStr(SE.getLoopDisposition(SV, InnerL));
9725 }
9726
9727 OS << " }";
9728 }
9729
9730 OS << "\n";
9731 }
9732
9733 OS << "Determining loop execution counts for: ";
9734 F.printAsOperand(OS, /*PrintType=*/false);
9735 OS << "\n";
9736 for (LoopInfo::iterator I = LI.begin(), E = LI.end(); I != E; ++I)
9737 PrintLoopInfo(OS, &SE, *I);
9738}
9739
9740ScalarEvolution::LoopDisposition
9741ScalarEvolution::getLoopDisposition(const SCEV *S, const Loop *L) {
9742 auto &Values = LoopDispositions[S];
9743 for (auto &V : Values) {
9744 if (V.getPointer() == L)
9745 return V.getInt();
9746 }
9747 Values.emplace_back(L, LoopVariant);
9748 LoopDisposition D = computeLoopDisposition(S, L);
9749 auto &Values2 = LoopDispositions[S];
9750 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
9751 if (V.getPointer() == L) {
9752 V.setInt(D);
9753 break;
9754 }
9755 }
9756 return D;
9757}
9758
9759ScalarEvolution::LoopDisposition
9760ScalarEvolution::computeLoopDisposition(const SCEV *S, const Loop *L) {
9761 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
9762 case scConstant:
9763 return LoopInvariant;
9764 case scTruncate:
9765 case scZeroExtend:
9766 case scSignExtend:
9767 return getLoopDisposition(cast<SCEVCastExpr>(S)->getOperand(), L);
9768 case scAddRecExpr: {
9769 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
9770
9771 // If L is the addrec's loop, it's computable.
9772 if (AR->getLoop() == L)
9773 return LoopComputable;
9774
9775 // Add recurrences are never invariant in the function-body (null loop).
9776 if (!L)
9777 return LoopVariant;
9778
9779 // This recurrence is variant w.r.t. L if L contains AR's loop.
9780 if (L->contains(AR->getLoop()))
9781 return LoopVariant;
9782
9783 // This recurrence is invariant w.r.t. L if AR's loop contains L.
9784 if (AR->getLoop()->contains(L))
9785 return LoopInvariant;
9786
9787 // This recurrence is variant w.r.t. L if any of its operands
9788 // are variant.
9789 for (auto *Op : AR->operands())
9790 if (!isLoopInvariant(Op, L))
9791 return LoopVariant;
9792
9793 // Otherwise it's loop-invariant.
9794 return LoopInvariant;
9795 }
9796 case scAddExpr:
9797 case scMulExpr:
9798 case scUMaxExpr:
9799 case scSMaxExpr: {
9800 bool HasVarying = false;
9801 for (auto *Op : cast<SCEVNAryExpr>(S)->operands()) {
9802 LoopDisposition D = getLoopDisposition(Op, L);
9803 if (D == LoopVariant)
9804 return LoopVariant;
9805 if (D == LoopComputable)
9806 HasVarying = true;
9807 }
9808 return HasVarying ? LoopComputable : LoopInvariant;
9809 }
9810 case scUDivExpr: {
9811 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
9812 LoopDisposition LD = getLoopDisposition(UDiv->getLHS(), L);
9813 if (LD == LoopVariant)
9814 return LoopVariant;
9815 LoopDisposition RD = getLoopDisposition(UDiv->getRHS(), L);
9816 if (RD == LoopVariant)
9817 return LoopVariant;
9818 return (LD == LoopInvariant && RD == LoopInvariant) ?
9819 LoopInvariant : LoopComputable;
9820 }
9821 case scUnknown:
9822 // All non-instruction values are loop invariant. All instructions are loop
9823 // invariant if they are not contained in the specified loop.
9824 // Instructions are never considered invariant in the function body
9825 // (null loop) because they are defined within the "loop".
9826 if (auto *I = dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue()))
9827 return (L && !L->contains(I)) ? LoopInvariant : LoopVariant;
9828 return LoopInvariant;
9829 case scCouldNotCompute:
9830 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9830)
;
9831 }
9832 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9832)
;
9833}
9834
9835bool ScalarEvolution::isLoopInvariant(const SCEV *S, const Loop *L) {
9836 return getLoopDisposition(S, L) == LoopInvariant;
9837}
9838
9839bool ScalarEvolution::hasComputableLoopEvolution(const SCEV *S, const Loop *L) {
9840 return getLoopDisposition(S, L) == LoopComputable;
9841}
9842
9843ScalarEvolution::BlockDisposition
9844ScalarEvolution::getBlockDisposition(const SCEV *S, const BasicBlock *BB) {
9845 auto &Values = BlockDispositions[S];
9846 for (auto &V : Values) {
9847 if (V.getPointer() == BB)
9848 return V.getInt();
9849 }
9850 Values.emplace_back(BB, DoesNotDominateBlock);
9851 BlockDisposition D = computeBlockDisposition(S, BB);
9852 auto &Values2 = BlockDispositions[S];
9853 for (auto &V : make_range(Values2.rbegin(), Values2.rend())) {
9854 if (V.getPointer() == BB) {
9855 V.setInt(D);
9856 break;
9857 }
9858 }
9859 return D;
9860}
9861
9862ScalarEvolution::BlockDisposition
9863ScalarEvolution::computeBlockDisposition(const SCEV *S, const BasicBlock *BB) {
9864 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
9865 case scConstant:
9866 return ProperlyDominatesBlock;
9867 case scTruncate:
9868 case scZeroExtend:
9869 case scSignExtend:
9870 return getBlockDisposition(cast<SCEVCastExpr>(S)->getOperand(), BB);
9871 case scAddRecExpr: {
9872 // This uses a "dominates" query instead of "properly dominates" query
9873 // to test for proper dominance too, because the instruction which
9874 // produces the addrec's value is a PHI, and a PHI effectively properly
9875 // dominates its entire containing block.
9876 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(S);
9877 if (!DT.dominates(AR->getLoop()->getHeader(), BB))
9878 return DoesNotDominateBlock;
9879 }
9880 // FALL THROUGH into SCEVNAryExpr handling.
9881 case scAddExpr:
9882 case scMulExpr:
9883 case scUMaxExpr:
9884 case scSMaxExpr: {
9885 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
9886 bool Proper = true;
9887 for (const SCEV *NAryOp : NAry->operands()) {
9888 BlockDisposition D = getBlockDisposition(NAryOp, BB);
9889 if (D == DoesNotDominateBlock)
9890 return DoesNotDominateBlock;
9891 if (D == DominatesBlock)
9892 Proper = false;
9893 }
9894 return Proper ? ProperlyDominatesBlock : DominatesBlock;
9895 }
9896 case scUDivExpr: {
9897 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
9898 const SCEV *LHS = UDiv->getLHS(), *RHS = UDiv->getRHS();
9899 BlockDisposition LD = getBlockDisposition(LHS, BB);
9900 if (LD == DoesNotDominateBlock)
9901 return DoesNotDominateBlock;
9902 BlockDisposition RD = getBlockDisposition(RHS, BB);
9903 if (RD == DoesNotDominateBlock)
9904 return DoesNotDominateBlock;
9905 return (LD == ProperlyDominatesBlock && RD == ProperlyDominatesBlock) ?
9906 ProperlyDominatesBlock : DominatesBlock;
9907 }
9908 case scUnknown:
9909 if (Instruction *I =
9910 dyn_cast<Instruction>(cast<SCEVUnknown>(S)->getValue())) {
9911 if (I->getParent() == BB)
9912 return DominatesBlock;
9913 if (DT.properlyDominates(I->getParent(), BB))
9914 return ProperlyDominatesBlock;
9915 return DoesNotDominateBlock;
9916 }
9917 return ProperlyDominatesBlock;
9918 case scCouldNotCompute:
9919 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9919)
;
9920 }
9921 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.9~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 9921)
;
9922}
9923
9924bool ScalarEvolution::dominates(const SCEV *S, const BasicBlock *BB) {
9925 return getBlockDisposition(S, BB) >= DominatesBlock;
9926}
9927
9928bool ScalarEvolution::properlyDominates(const SCEV *S, const BasicBlock *BB) {
9929 return getBlockDisposition(S, BB) == ProperlyDominatesBlock;
9930}
9931
9932bool ScalarEvolution::hasOperand(const SCEV *S, const SCEV *Op) const {
9933 // Search for a SCEV expression node within an expression tree.
9934 // Implements SCEVTraversal::Visitor.
9935 struct SCEVSearch {
9936 const SCEV *Node;
9937 bool IsFound;
9938
9939 SCEVSearch(const SCEV *N): Node(N), IsFound(false) {}
9940
9941 bool follow(const SCEV *S) {
9942 IsFound |= (S == Node);
9943 return !IsFound;
9944 }
9945 bool isDone() const { return IsFound; }
9946 };
9947
9948 SCEVSearch Search(Op);
9949 visitAll(S, Search);
9950 return Search.IsFound;
9951}
9952
9953void ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
9954 ValuesAtScopes.erase(S);
9955 LoopDispositions.erase(S);
9956 BlockDispositions.erase(S);
9957 UnsignedRanges.erase(S);
9958 SignedRanges.erase(S);
9959 ExprValueMap.erase(S);
9960 HasRecMap.erase(S);
9961
9962 auto RemoveSCEVFromBackedgeMap =
9963 [S, this](DenseMap<const Loop *, BackedgeTakenInfo> &Map) {
9964 for (auto I = Map.begin(), E = Map.end(); I != E;) {
9965 BackedgeTakenInfo &BEInfo = I->second;
9966 if (BEInfo.hasOperand(S, this)) {
9967 BEInfo.clear();
9968 Map.erase(I++);
9969 } else
9970 ++I;
9971 }
9972 };
9973
9974 RemoveSCEVFromBackedgeMap(BackedgeTakenCounts);
9975 RemoveSCEVFromBackedgeMap(PredicatedBackedgeTakenCounts);
9976}
9977
9978typedef DenseMap<const Loop *, std::string> VerifyMap;
9979
9980/// replaceSubString - Replaces all occurrences of From in Str with To.
9981static void replaceSubString(std::string &Str, StringRef From, StringRef To) {
9982 size_t Pos = 0;
9983 while ((Pos = Str.find(From, Pos)) != std::string::npos) {
9984 Str.replace(Pos, From.size(), To.data(), To.size());
9985 Pos += To.size();
9986 }
9987}
9988
9989/// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis.
9990static void
9991getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) {
9992 std::string &S = Map[L];
9993 if (S.empty()) {
9994 raw_string_ostream OS(S);
9995 SE.getBackedgeTakenCount(L)->print(OS);
9996
9997 // false and 0 are semantically equivalent. This can happen in dead loops.
9998 replaceSubString(OS.str(), "false", "0");
9999 // Remove wrap flags, their use in SCEV is highly fragile.
10000 // FIXME: Remove this when SCEV gets smarter about them.
10001 replaceSubString(OS.str(), "<nw>", "");
10002 replaceSubString(OS.str(), "<nsw>", "");
10003 replaceSubString(OS.str(), "<nuw>", "");
10004 }
10005
10006 for (auto *R : reverse(*L))
10007 getLoopBackedgeTakenCounts(R, Map, SE); // recurse.
10008}
10009
10010void ScalarEvolution::verify() const {
10011 ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
10012
10013 // Gather stringified backedge taken counts for all loops using SCEV's caches.
10014 // FIXME: It would be much better to store actual values instead of strings,
10015 // but SCEV pointers will change if we drop the caches.
10016 VerifyMap BackedgeDumpsOld, BackedgeDumpsNew;
10017 for (LoopInfo::reverse_iterator I = LI.rbegin(), E = LI.rend(); I != E; ++I)
10018 getLoopBackedgeTakenCounts(*I, BackedgeDumpsOld, SE);
10019
10020 // Gather stringified backedge taken counts for all loops using a fresh
10021 // ScalarEvolution object.
10022 ScalarEvolution SE2(F, TLI, AC, DT, LI);
10023 for (LoopInfo::reverse_iterator I = LI.rbegin(), E = LI.rend(); I != E; ++I)
10024 getLoopBackedgeTakenCounts(*I, BackedgeDumpsNew, SE2);
10025
10026 // Now compare whether they're the same with and without caches. This allows
10027 // verifying that no pass changed the cache.
10028 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 10029, __PRETTY_FUNCTION__))
10029 "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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 10029, __PRETTY_FUNCTION__))
;
10030
10031 for (VerifyMap::iterator OldI = BackedgeDumpsOld.begin(),
10032 OldE = BackedgeDumpsOld.end(),
10033 NewI = BackedgeDumpsNew.begin();
10034 OldI != OldE; ++OldI, ++NewI) {
10035 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 10035, __PRETTY_FUNCTION__))
;
10036
10037 // Compare the stringified SCEVs. We don't care if undef backedgetaken count
10038 // changes.
10039 // FIXME: We currently ignore SCEV changes from/to CouldNotCompute. This
10040 // means that a pass is buggy or SCEV has to learn a new pattern but is
10041 // usually not harmful.
10042 if (OldI->second != NewI->second &&
10043 OldI->second.find("undef") == std::string::npos &&
10044 NewI->second.find("undef") == std::string::npos &&
10045 OldI->second != "***COULDNOTCOMPUTE***" &&
10046 NewI->second != "***COULDNOTCOMPUTE***") {
10047 dbgs() << "SCEVValidator: SCEV for loop '"
10048 << OldI->first->getHeader()->getName()
10049 << "' changed from '" << OldI->second
10050 << "' to '" << NewI->second << "'!\n";
10051 std::abort();
10052 }
10053 }
10054
10055 // TODO: Verify more things.
10056}
10057
10058char ScalarEvolutionAnalysis::PassID;
10059
10060ScalarEvolution ScalarEvolutionAnalysis::run(Function &F,
10061 AnalysisManager<Function> &AM) {
10062 return ScalarEvolution(F, AM.getResult<TargetLibraryAnalysis>(F),
10063 AM.getResult<AssumptionAnalysis>(F),
10064 AM.getResult<DominatorTreeAnalysis>(F),
10065 AM.getResult<LoopAnalysis>(F));
10066}
10067
10068PreservedAnalyses
10069ScalarEvolutionPrinterPass::run(Function &F, AnalysisManager<Function> &AM) {
10070 AM.getResult<ScalarEvolutionAnalysis>(F).print(OS);
10071 return PreservedAnalyses::all();
10072}
10073
10074INITIALIZE_PASS_BEGIN(ScalarEvolutionWrapperPass, "scalar-evolution",static void* initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
10075 "Scalar Evolution Analysis", false, true)static void* initializeScalarEvolutionWrapperPassPassOnce(PassRegistry
&Registry) {
10076INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
10077INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
10078INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
10079INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
10080INITIALIZE_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(); } } ; }
10081 "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(); } } ; }
10082char ScalarEvolutionWrapperPass::ID = 0;
10083
10084ScalarEvolutionWrapperPass::ScalarEvolutionWrapperPass() : FunctionPass(ID) {
10085 initializeScalarEvolutionWrapperPassPass(*PassRegistry::getPassRegistry());
10086}
10087
10088bool ScalarEvolutionWrapperPass::runOnFunction(Function &F) {
10089 SE.reset(new ScalarEvolution(
10090 F, getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
10091 getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
10092 getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
10093 getAnalysis<LoopInfoWrapperPass>().getLoopInfo()));
10094 return false;
10095}
10096
10097void ScalarEvolutionWrapperPass::releaseMemory() { SE.reset(); }
10098
10099void ScalarEvolutionWrapperPass::print(raw_ostream &OS, const Module *) const {
10100 SE->print(OS);
10101}
10102
10103void ScalarEvolutionWrapperPass::verifyAnalysis() const {
10104 if (!VerifySCEV)
10105 return;
10106
10107 SE->verify();
10108}
10109
10110void ScalarEvolutionWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
10111 AU.setPreservesAll();
10112 AU.addRequiredTransitive<AssumptionCacheTracker>();
10113 AU.addRequiredTransitive<LoopInfoWrapperPass>();
10114 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
10115 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
10116}
10117
10118const SCEVPredicate *
10119ScalarEvolution::getEqualPredicate(const SCEVUnknown *LHS,
10120 const SCEVConstant *RHS) {
10121 FoldingSetNodeID ID;
10122 // Unique this node based on the arguments
10123 ID.AddInteger(SCEVPredicate::P_Equal);
10124 ID.AddPointer(LHS);
10125 ID.AddPointer(RHS);
10126 void *IP = nullptr;
10127 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
10128 return S;
10129 SCEVEqualPredicate *Eq = new (SCEVAllocator)
10130 SCEVEqualPredicate(ID.Intern(SCEVAllocator), LHS, RHS);
10131 UniquePreds.InsertNode(Eq, IP);
10132 return Eq;
10133}
10134
10135const SCEVPredicate *ScalarEvolution::getWrapPredicate(
10136 const SCEVAddRecExpr *AR,
10137 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
10138 FoldingSetNodeID ID;
10139 // Unique this node based on the arguments
10140 ID.AddInteger(SCEVPredicate::P_Wrap);
10141 ID.AddPointer(AR);
10142 ID.AddInteger(AddedFlags);
10143 void *IP = nullptr;
10144 if (const auto *S = UniquePreds.FindNodeOrInsertPos(ID, IP))
10145 return S;
10146 auto *OF = new (SCEVAllocator)
10147 SCEVWrapPredicate(ID.Intern(SCEVAllocator), AR, AddedFlags);
10148 UniquePreds.InsertNode(OF, IP);
10149 return OF;
10150}
10151
10152namespace {
10153
10154class SCEVPredicateRewriter : public SCEVRewriteVisitor<SCEVPredicateRewriter> {
10155public:
10156 // Rewrites \p S in the context of a loop L and the predicate A.
10157 // If Assume is true, rewrite is free to add further predicates to A
10158 // such that the result will be an AddRecExpr.
10159 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
10160 SCEVUnionPredicate &A, bool Assume) {
10161 SCEVPredicateRewriter Rewriter(L, SE, A, Assume);
10162 return Rewriter.visit(S);
10163 }
10164
10165 SCEVPredicateRewriter(const Loop *L, ScalarEvolution &SE,
10166 SCEVUnionPredicate &P, bool Assume)
10167 : SCEVRewriteVisitor(SE), P(P), L(L), Assume(Assume) {}
10168
10169 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
10170 auto ExprPreds = P.getPredicatesForExpr(Expr);
10171 for (auto *Pred : ExprPreds)
10172 if (const auto *IPred = dyn_cast<const SCEVEqualPredicate>(Pred))
10173 if (IPred->getLHS() == Expr)
10174 return IPred->getRHS();
10175
10176 return Expr;
10177 }
10178
10179 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
10180 const SCEV *Operand = visit(Expr->getOperand());
10181 const SCEVAddRecExpr *AR = dyn_cast<const SCEVAddRecExpr>(Operand);
10182 if (AR && AR->getLoop() == L && AR->isAffine()) {
10183 // This couldn't be folded because the operand didn't have the nuw
10184 // flag. Add the nusw flag as an assumption that we could make.
10185 const SCEV *Step = AR->getStepRecurrence(SE);
10186 Type *Ty = Expr->getType();
10187 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNUSW))
10188 return SE.getAddRecExpr(SE.getZeroExtendExpr(AR->getStart(), Ty),
10189 SE.getSignExtendExpr(Step, Ty), L,
10190 AR->getNoWrapFlags());
10191 }
10192 return SE.getZeroExtendExpr(Operand, Expr->getType());
10193 }
10194
10195 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
10196 const SCEV *Operand = visit(Expr->getOperand());
10197 const SCEVAddRecExpr *AR = dyn_cast<const SCEVAddRecExpr>(Operand);
10198 if (AR && AR->getLoop() == L && AR->isAffine()) {
10199 // This couldn't be folded because the operand didn't have the nsw
10200 // flag. Add the nssw flag as an assumption that we could make.
10201 const SCEV *Step = AR->getStepRecurrence(SE);
10202 Type *Ty = Expr->getType();
10203 if (addOverflowAssumption(AR, SCEVWrapPredicate::IncrementNSSW))
10204 return SE.getAddRecExpr(SE.getSignExtendExpr(AR->getStart(), Ty),
10205 SE.getSignExtendExpr(Step, Ty), L,
10206 AR->getNoWrapFlags());
10207 }
10208 return SE.getSignExtendExpr(Operand, Expr->getType());
10209 }
10210
10211private:
10212 bool addOverflowAssumption(const SCEVAddRecExpr *AR,
10213 SCEVWrapPredicate::IncrementWrapFlags AddedFlags) {
10214 auto *A = SE.getWrapPredicate(AR, AddedFlags);
10215 if (!Assume) {
10216 // Check if we've already made this assumption.
10217 if (P.implies(A))
10218 return true;
10219 return false;
10220 }
10221 P.add(A);
10222 return true;
10223 }
10224
10225 SCEVUnionPredicate &P;
10226 const Loop *L;
10227 bool Assume;
10228};
10229} // end anonymous namespace
10230
10231const SCEV *ScalarEvolution::rewriteUsingPredicate(const SCEV *S, const Loop *L,
10232 SCEVUnionPredicate &Preds) {
10233 return SCEVPredicateRewriter::rewrite(S, L, *this, Preds, false);
10234}
10235
10236const SCEVAddRecExpr *
10237ScalarEvolution::convertSCEVToAddRecWithPredicates(const SCEV *S, const Loop *L,
10238 SCEVUnionPredicate &Preds) {
10239 SCEVUnionPredicate TransformPreds;
10240 S = SCEVPredicateRewriter::rewrite(S, L, *this, TransformPreds, true);
10241 auto *AddRec = dyn_cast<SCEVAddRecExpr>(S);
10242
10243 if (!AddRec)
10244 return nullptr;
10245
10246 // Since the transformation was successful, we can now transfer the SCEV
10247 // predicates.
10248 Preds.add(&TransformPreds);
10249 return AddRec;
10250}
10251
10252/// SCEV predicates
10253SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
10254 SCEVPredicateKind Kind)
10255 : FastID(ID), Kind(Kind) {}
10256
10257SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID,
10258 const SCEVUnknown *LHS,
10259 const SCEVConstant *RHS)
10260 : SCEVPredicate(ID, P_Equal), LHS(LHS), RHS(RHS) {}
10261
10262bool SCEVEqualPredicate::implies(const SCEVPredicate *N) const {
10263 const auto *Op = dyn_cast<const SCEVEqualPredicate>(N);
10264
10265 if (!Op)
10266 return false;
10267
10268 return Op->LHS == LHS && Op->RHS == RHS;
10269}
10270
10271bool SCEVEqualPredicate::isAlwaysTrue() const { return false; }
10272
10273const SCEV *SCEVEqualPredicate::getExpr() const { return LHS; }
10274
10275void SCEVEqualPredicate::print(raw_ostream &OS, unsigned Depth) const {
10276 OS.indent(Depth) << "Equal predicate: " << *LHS << " == " << *RHS << "\n";
10277}
10278
10279SCEVWrapPredicate::SCEVWrapPredicate(const FoldingSetNodeIDRef ID,
10280 const SCEVAddRecExpr *AR,
10281 IncrementWrapFlags Flags)
10282 : SCEVPredicate(ID, P_Wrap), AR(AR), Flags(Flags) {}
10283
10284const SCEV *SCEVWrapPredicate::getExpr() const { return AR; }
10285
10286bool SCEVWrapPredicate::implies(const SCEVPredicate *N) const {
10287 const auto *Op = dyn_cast<SCEVWrapPredicate>(N);
10288
10289 return Op && Op->AR == AR && setFlags(Flags, Op->Flags) == Flags;
10290}
10291
10292bool SCEVWrapPredicate::isAlwaysTrue() const {
10293 SCEV::NoWrapFlags ScevFlags = AR->getNoWrapFlags();
10294 IncrementWrapFlags IFlags = Flags;
10295
10296 if (ScalarEvolution::setFlags(ScevFlags, SCEV::FlagNSW) == ScevFlags)
10297 IFlags = clearFlags(IFlags, IncrementNSSW);
10298
10299 return IFlags == IncrementAnyWrap;
10300}
10301
10302void SCEVWrapPredicate::print(raw_ostream &OS, unsigned Depth) const {
10303 OS.indent(Depth) << *getExpr() << " Added Flags: ";
10304 if (SCEVWrapPredicate::IncrementNUSW & getFlags())
10305 OS << "<nusw>";
10306 if (SCEVWrapPredicate::IncrementNSSW & getFlags())
10307 OS << "<nssw>";
10308 OS << "\n";
10309}
10310
10311SCEVWrapPredicate::IncrementWrapFlags
10312SCEVWrapPredicate::getImpliedFlags(const SCEVAddRecExpr *AR,
10313 ScalarEvolution &SE) {
10314 IncrementWrapFlags ImpliedFlags = IncrementAnyWrap;
10315 SCEV::NoWrapFlags StaticFlags = AR->getNoWrapFlags();
10316
10317 // We can safely transfer the NSW flag as NSSW.
10318 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNSW) == StaticFlags)
10319 ImpliedFlags = IncrementNSSW;
10320
10321 if (ScalarEvolution::setFlags(StaticFlags, SCEV::FlagNUW) == StaticFlags) {
10322 // If the increment is positive, the SCEV NUW flag will also imply the
10323 // WrapPredicate NUSW flag.
10324 if (const auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(SE)))
10325 if (Step->getValue()->getValue().isNonNegative())
10326 ImpliedFlags = setFlags(ImpliedFlags, IncrementNUSW);
10327 }
10328
10329 return ImpliedFlags;
10330}
10331
10332/// Union predicates don't get cached so create a dummy set ID for it.
10333SCEVUnionPredicate::SCEVUnionPredicate()
10334 : SCEVPredicate(FoldingSetNodeIDRef(nullptr, 0), P_Union) {}
10335
10336bool SCEVUnionPredicate::isAlwaysTrue() const {
10337 return all_of(Preds,
10338 [](const SCEVPredicate *I) { return I->isAlwaysTrue(); });
10339}
10340
10341ArrayRef<const SCEVPredicate *>
10342SCEVUnionPredicate::getPredicatesForExpr(const SCEV *Expr) {
10343 auto I = SCEVToPreds.find(Expr);
10344 if (I == SCEVToPreds.end())
10345 return ArrayRef<const SCEVPredicate *>();
10346 return I->second;
10347}
10348
10349bool SCEVUnionPredicate::implies(const SCEVPredicate *N) const {
10350 if (const auto *Set = dyn_cast<const SCEVUnionPredicate>(N))
10351 return all_of(Set->Preds,
10352 [this](const SCEVPredicate *I) { return this->implies(I); });
10353
10354 auto ScevPredsIt = SCEVToPreds.find(N->getExpr());
10355 if (ScevPredsIt == SCEVToPreds.end())
10356 return false;
10357 auto &SCEVPreds = ScevPredsIt->second;
10358
10359 return any_of(SCEVPreds,
10360 [N](const SCEVPredicate *I) { return I->implies(N); });
10361}
10362
10363const SCEV *SCEVUnionPredicate::getExpr() const { return nullptr; }
10364
10365void SCEVUnionPredicate::print(raw_ostream &OS, unsigned Depth) const {
10366 for (auto Pred : Preds)
10367 Pred->print(OS, Depth);
10368}
10369
10370void SCEVUnionPredicate::add(const SCEVPredicate *N) {
10371 if (const auto *Set = dyn_cast<const SCEVUnionPredicate>(N)) {
10372 for (auto Pred : Set->Preds)
10373 add(Pred);
10374 return;
10375 }
10376
10377 if (implies(N))
10378 return;
10379
10380 const SCEV *Key = N->getExpr();
10381 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 10382, __PRETTY_FUNCTION__))
10382 " 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~svn271111/lib/Analysis/ScalarEvolution.cpp"
, 10382, __PRETTY_FUNCTION__))
;
10383
10384 SCEVToPreds[Key].push_back(N);
10385 Preds.push_back(N);
10386}
10387
10388PredicatedScalarEvolution::PredicatedScalarEvolution(ScalarEvolution &SE,
10389 Loop &L)
10390 : SE(SE), L(L), Generation(0), BackedgeCount(nullptr) {}
10391
10392const SCEV *PredicatedScalarEvolution::getSCEV(Value *V) {
10393 const SCEV *Expr = SE.getSCEV(V);
10394 RewriteEntry &Entry = RewriteMap[Expr];
10395
10396 // If we already have an entry and the version matches, return it.
10397 if (Entry.second && Generation == Entry.first)
10398 return Entry.second;
10399
10400 // We found an entry but it's stale. Rewrite the stale entry
10401 // acording to the current predicate.
10402 if (Entry.second)
10403 Expr = Entry.second;
10404
10405 const SCEV *NewSCEV = SE.rewriteUsingPredicate(Expr, &L, Preds);
10406 Entry = {Generation, NewSCEV};
10407
10408 return NewSCEV;
10409}
10410
10411const SCEV *PredicatedScalarEvolution::getBackedgeTakenCount() {
10412 if (!BackedgeCount) {
10413 SCEVUnionPredicate BackedgePred;
10414 BackedgeCount = SE.getPredicatedBackedgeTakenCount(&L, BackedgePred);
10415 addPredicate(BackedgePred);
10416 }
10417 return BackedgeCount;
10418}
10419
10420void PredicatedScalarEvolution::addPredicate(const SCEVPredicate &Pred) {
10421 if (Preds.implies(&Pred))
10422 return;
10423 Preds.add(&Pred);
10424 updateGeneration();
10425}
10426
10427const SCEVUnionPredicate &PredicatedScalarEvolution::getUnionPredicate() const {
10428 return Preds;
10429}
10430
10431void PredicatedScalarEvolution::updateGeneration() {
10432 // If the generation number wrapped recompute everything.
10433 if (++Generation == 0) {
10434 for (auto &II : RewriteMap) {
10435 const SCEV *Rewritten = II.second.second;
10436 II.second = {Generation, SE.rewriteUsingPredicate(Rewritten, &L, Preds)};
10437 }
10438 }
10439}
10440
10441void PredicatedScalarEvolution::setNoOverflow(
10442 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
10443 const SCEV *Expr = getSCEV(V);
10444 const auto *AR = cast<SCEVAddRecExpr>(Expr);
10445
10446 auto ImpliedFlags = SCEVWrapPredicate::getImpliedFlags(AR, SE);
10447
10448 // Clear the statically implied flags.
10449 Flags = SCEVWrapPredicate::clearFlags(Flags, ImpliedFlags);
10450 addPredicate(*SE.getWrapPredicate(AR, Flags));
10451
10452 auto II = FlagsMap.insert({V, Flags});
10453 if (!II.second)
10454 II.first->second = SCEVWrapPredicate::setFlags(Flags, II.first->second);
10455}
10456
10457bool PredicatedScalarEvolution::hasNoOverflow(
10458 Value *V, SCEVWrapPredicate::IncrementWrapFlags Flags) {
10459 const SCEV *Expr = getSCEV(V);
10460 const auto *AR = cast<SCEVAddRecExpr>(Expr);
10461
10462 Flags = SCEVWrapPredicate::clearFlags(
10463 Flags, SCEVWrapPredicate::getImpliedFlags(AR, SE));
10464
10465 auto II = FlagsMap.find(V);
10466
10467 if (II != FlagsMap.end())
10468 Flags = SCEVWrapPredicate::clearFlags(Flags, II->second);
10469
10470 return Flags == SCEVWrapPredicate::IncrementAnyWrap;
10471}
10472
10473const SCEVAddRecExpr *PredicatedScalarEvolution::getAsAddRec(Value *V) {
10474 const SCEV *Expr = this->getSCEV(V);
10475 auto *New = SE.convertSCEVToAddRecWithPredicates(Expr, &L, Preds);
10476
10477 if (!New)
10478 return nullptr;
10479
10480 updateGeneration();
10481 RewriteMap[SE.getSCEV(V)] = {Generation, New};
10482 return New;
10483}
10484
10485PredicatedScalarEvolution::PredicatedScalarEvolution(
10486 const PredicatedScalarEvolution &Init)
10487 : RewriteMap(Init.RewriteMap), SE(Init.SE), L(Init.L), Preds(Init.Preds),
10488 Generation(Init.Generation), BackedgeCount(Init.BackedgeCount) {
10489 for (auto I = Init.FlagsMap.begin(), E = Init.FlagsMap.end(); I != E; ++I)
10490 FlagsMap.insert(*I);
10491}
10492
10493void PredicatedScalarEvolution::print(raw_ostream &OS, unsigned Depth) const {
10494 // For each block.
10495 for (auto *BB : L.getBlocks())
10496 for (auto &I : *BB) {
10497 if (!SE.isSCEVable(I.getType()))
10498 continue;
10499
10500 auto *Expr = SE.getSCEV(&I);
10501 auto II = RewriteMap.find(Expr);
10502
10503 if (II == RewriteMap.end())
10504 continue;
10505
10506 // Don't print things that are not interesting.
10507 if (II->second.second == Expr)
10508 continue;
10509
10510 OS.indent(Depth) << "[PSE]" << I << ":\n";
10511 OS.indent(Depth + 2) << *Expr << "\n";
10512 OS.indent(Depth + 2) << "--> " << *II->second.second << "\n";
10513 }
10514}