1//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// InstructionCombining - Combine instructions to form fewer, simple
10// instructions. This pass does not modify the CFG. This pass is where
11// algebraic simplification happens.
12//
13// This pass combines things like:
14// %Y = add i32 %X, 1
15// %Z = add i32 %Y, 1
16// into:
17// %Z = add i32 %X, 2
18//
19// This is a simple worklist driven algorithm.
20//
21// This pass guarantees that the following canonicalizations are performed on
22// the program:
23// 1. If a binary operator has a constant operand, it is moved to the RHS
24// 2. Bitwise operators with constant operands are always grouped so that
25// shifts are performed first, then or's, then and's, then xor's.
26// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
27// 4. All cmp instructions on boolean values are replaced with logical ops
28// 5. add X, X is represented as (X*2) => (X << 1)
29// 6. Multiplies with a power-of-two constant argument are transformed into
30// shifts.
31// ... etc.
32//
33//===----------------------------------------------------------------------===//
34
35#include "InstCombineInternal.h"
36#include "llvm/ADT/APFloat.h"
37#include "llvm/ADT/APInt.h"
38#include "llvm/ADT/ArrayRef.h"
39#include "llvm/ADT/DenseMap.h"
40#include "llvm/ADT/SmallPtrSet.h"
41#include "llvm/ADT/SmallVector.h"
42#include "llvm/ADT/Statistic.h"
43#include "llvm/Analysis/AliasAnalysis.h"
44#include "llvm/Analysis/AssumptionCache.h"
45#include "llvm/Analysis/BasicAliasAnalysis.h"
46#include "llvm/Analysis/BlockFrequencyInfo.h"
47#include "llvm/Analysis/CFG.h"
48#include "llvm/Analysis/ConstantFolding.h"
49#include "llvm/Analysis/GlobalsModRef.h"
50#include "llvm/Analysis/InstructionSimplify.h"
51#include "llvm/Analysis/LastRunTrackingAnalysis.h"
52#include "llvm/Analysis/LazyBlockFrequencyInfo.h"
53#include "llvm/Analysis/MemoryBuiltins.h"
54#include "llvm/Analysis/OptimizationRemarkEmitter.h"
55#include "llvm/Analysis/ProfileSummaryInfo.h"
56#include "llvm/Analysis/TargetFolder.h"
57#include "llvm/Analysis/TargetLibraryInfo.h"
58#include "llvm/Analysis/TargetTransformInfo.h"
59#include "llvm/Analysis/Utils/Local.h"
60#include "llvm/Analysis/ValueTracking.h"
61#include "llvm/Analysis/VectorUtils.h"
62#include "llvm/IR/BasicBlock.h"
63#include "llvm/IR/CFG.h"
64#include "llvm/IR/Constant.h"
65#include "llvm/IR/Constants.h"
66#include "llvm/IR/DIBuilder.h"
67#include "llvm/IR/DataLayout.h"
68#include "llvm/IR/DebugInfo.h"
69#include "llvm/IR/DerivedTypes.h"
70#include "llvm/IR/Dominators.h"
71#include "llvm/IR/EHPersonalities.h"
72#include "llvm/IR/Function.h"
73#include "llvm/IR/GetElementPtrTypeIterator.h"
74#include "llvm/IR/IRBuilder.h"
75#include "llvm/IR/InstrTypes.h"
76#include "llvm/IR/Instruction.h"
77#include "llvm/IR/Instructions.h"
78#include "llvm/IR/IntrinsicInst.h"
79#include "llvm/IR/Intrinsics.h"
80#include "llvm/IR/Metadata.h"
81#include "llvm/IR/Operator.h"
82#include "llvm/IR/PassManager.h"
83#include "llvm/IR/PatternMatch.h"
84#include "llvm/IR/Type.h"
85#include "llvm/IR/Use.h"
86#include "llvm/IR/User.h"
87#include "llvm/IR/Value.h"
88#include "llvm/IR/ValueHandle.h"
89#include "llvm/InitializePasses.h"
90#include "llvm/Support/Casting.h"
91#include "llvm/Support/CommandLine.h"
92#include "llvm/Support/Compiler.h"
93#include "llvm/Support/Debug.h"
94#include "llvm/Support/DebugCounter.h"
95#include "llvm/Support/ErrorHandling.h"
96#include "llvm/Support/KnownBits.h"
97#include "llvm/Support/KnownFPClass.h"
98#include "llvm/Support/raw_ostream.h"
99#include "llvm/Transforms/InstCombine/InstCombine.h"
100#include "llvm/Transforms/Utils/BasicBlockUtils.h"
101#include "llvm/Transforms/Utils/Local.h"
102#include <algorithm>
103#include <cassert>
104#include <cstdint>
105#include <memory>
106#include <optional>
107#include <string>
108#include <utility>
109
110#define DEBUG_TYPE "instcombine"
111#include "llvm/Transforms/Utils/InstructionWorklist.h"
112#include <optional>
113
114using namespace llvm;
115using namespace llvm::PatternMatch;
116
117STATISTIC(NumWorklistIterations,
118 "Number of instruction combining iterations performed");
119STATISTIC(NumOneIteration, "Number of functions with one iteration");
120STATISTIC(NumTwoIterations, "Number of functions with two iterations");
121STATISTIC(NumThreeIterations, "Number of functions with three iterations");
122STATISTIC(NumFourOrMoreIterations,
123 "Number of functions with four or more iterations");
124
125STATISTIC(NumCombined , "Number of insts combined");
126STATISTIC(NumConstProp, "Number of constant folds");
127STATISTIC(NumDeadInst , "Number of dead inst eliminated");
128STATISTIC(NumSunkInst , "Number of instructions sunk");
129STATISTIC(NumExpand, "Number of expansions");
130STATISTIC(NumFactor , "Number of factorizations");
131STATISTIC(NumReassoc , "Number of reassociations");
132DEBUG_COUNTER(VisitCounter, "instcombine-visit",
133 "Controls which instructions are visited");
134
135static cl::opt<bool>
136EnableCodeSinking("instcombine-code-sinking", cl::desc("Enable code sinking"),
137 cl::init(Val: true));
138
139static cl::opt<unsigned> MaxSinkNumUsers(
140 "instcombine-max-sink-users", cl::init(Val: 32),
141 cl::desc("Maximum number of undroppable users for instruction sinking"));
142
143static cl::opt<unsigned>
144MaxArraySize("instcombine-maxarray-size", cl::init(Val: 1024),
145 cl::desc("Maximum array size considered when doing a combine"));
146
147// FIXME: Remove this flag when it is no longer necessary to convert
148// llvm.dbg.declare to avoid inaccurate debug info. Setting this to false
149// increases variable availability at the cost of accuracy. Variables that
150// cannot be promoted by mem2reg or SROA will be described as living in memory
151// for their entire lifetime. However, passes like DSE and instcombine can
152// delete stores to the alloca, leading to misleading and inaccurate debug
153// information. This flag can be removed when those passes are fixed.
154static cl::opt<unsigned> ShouldLowerDbgDeclare("instcombine-lower-dbg-declare",
155 cl::Hidden, cl::init(Val: true));
156
157std::optional<Instruction *>
158InstCombiner::targetInstCombineIntrinsic(IntrinsicInst &II) {
159 // Handle target specific intrinsics
160 if (II.getCalledFunction()->isTargetIntrinsic()) {
161 return TTIForTargetIntrinsicsOnly.instCombineIntrinsic(IC&: *this, II);
162 }
163 return std::nullopt;
164}
165
166std::optional<Value *> InstCombiner::targetSimplifyDemandedUseBitsIntrinsic(
167 IntrinsicInst &II, APInt DemandedMask, KnownBits &Known,
168 bool &KnownBitsComputed) {
169 // Handle target specific intrinsics
170 if (II.getCalledFunction()->isTargetIntrinsic()) {
171 return TTIForTargetIntrinsicsOnly.simplifyDemandedUseBitsIntrinsic(
172 IC&: *this, II, DemandedMask, Known, KnownBitsComputed);
173 }
174 return std::nullopt;
175}
176
177std::optional<Value *> InstCombiner::targetSimplifyDemandedVectorEltsIntrinsic(
178 IntrinsicInst &II, APInt DemandedElts, APInt &PoisonElts,
179 APInt &PoisonElts2, APInt &PoisonElts3,
180 std::function<void(Instruction *, unsigned, APInt, APInt &)>
181 SimplifyAndSetOp) {
182 // Handle target specific intrinsics
183 if (II.getCalledFunction()->isTargetIntrinsic()) {
184 return TTIForTargetIntrinsicsOnly.simplifyDemandedVectorEltsIntrinsic(
185 IC&: *this, II, DemandedElts, UndefElts&: PoisonElts, UndefElts2&: PoisonElts2, UndefElts3&: PoisonElts3,
186 SimplifyAndSetOp);
187 }
188 return std::nullopt;
189}
190
191bool InstCombiner::isValidAddrSpaceCast(unsigned FromAS, unsigned ToAS) const {
192 // Approved exception for TTI use: This queries a legality property of the
193 // target, not an profitability heuristic. Ideally this should be part of
194 // DataLayout instead.
195 return TTIForTargetIntrinsicsOnly.isValidAddrSpaceCast(FromAS, ToAS);
196}
197
198Value *InstCombinerImpl::EmitGEPOffset(GEPOperator *GEP, bool RewriteGEP) {
199 if (!RewriteGEP)
200 return llvm::emitGEPOffset(Builder: &Builder, DL, GEP);
201
202 IRBuilderBase::InsertPointGuard Guard(Builder);
203 auto *Inst = dyn_cast<Instruction>(Val: GEP);
204 if (Inst)
205 Builder.SetInsertPoint(Inst);
206
207 Value *Offset = EmitGEPOffset(GEP);
208 // Rewrite non-trivial GEPs to avoid duplicating the offset arithmetic.
209 if (Inst && !GEP->hasAllConstantIndices() &&
210 !GEP->getSourceElementType()->isIntegerTy(Bitwidth: 8)) {
211 replaceInstUsesWith(
212 I&: *Inst, V: Builder.CreateGEP(Ty: Builder.getInt8Ty(), Ptr: GEP->getPointerOperand(),
213 IdxList: Offset, Name: "", NW: GEP->getNoWrapFlags()));
214 eraseInstFromFunction(I&: *Inst);
215 }
216 return Offset;
217}
218
219Value *InstCombinerImpl::EmitGEPOffsets(ArrayRef<GEPOperator *> GEPs,
220 GEPNoWrapFlags NW, Type *IdxTy,
221 bool RewriteGEPs) {
222 Value *Sum = nullptr;
223 for (GEPOperator *GEP : reverse(C&: GEPs)) {
224 Value *Offset = EmitGEPOffset(GEP, RewriteGEP: RewriteGEPs);
225 if (Offset->getType() != IdxTy)
226 Offset = Builder.CreateVectorSplat(
227 EC: cast<VectorType>(Val: IdxTy)->getElementCount(), V: Offset);
228 if (Sum)
229 Sum = Builder.CreateAdd(LHS: Sum, RHS: Offset, Name: "", HasNUW: NW.hasNoUnsignedWrap(),
230 HasNSW: NW.isInBounds());
231 else
232 Sum = Offset;
233 }
234 if (!Sum)
235 return Constant::getNullValue(Ty: IdxTy);
236 return Sum;
237}
238
239/// Legal integers and common types are considered desirable. This is used to
240/// avoid creating instructions with types that may not be supported well by the
241/// the backend.
242/// NOTE: This treats i8, i16 and i32 specially because they are common
243/// types in frontend languages.
244bool InstCombinerImpl::isDesirableIntType(unsigned BitWidth) const {
245 switch (BitWidth) {
246 case 8:
247 case 16:
248 case 32:
249 return true;
250 default:
251 return DL.isLegalInteger(Width: BitWidth);
252 }
253}
254
255/// Return true if it is desirable to convert an integer computation from a
256/// given bit width to a new bit width.
257/// We don't want to convert from a legal or desirable type (like i8) to an
258/// illegal type or from a smaller to a larger illegal type. A width of '1'
259/// is always treated as a desirable type because i1 is a fundamental type in
260/// IR, and there are many specialized optimizations for i1 types.
261/// Common/desirable widths are equally treated as legal to convert to, in
262/// order to open up more combining opportunities.
263bool InstCombinerImpl::shouldChangeType(unsigned FromWidth,
264 unsigned ToWidth) const {
265 bool FromLegal = FromWidth == 1 || DL.isLegalInteger(Width: FromWidth);
266 bool ToLegal = ToWidth == 1 || DL.isLegalInteger(Width: ToWidth);
267
268 // Convert to desirable widths even if they are not legal types.
269 // Only shrink types, to prevent infinite loops.
270 if (ToWidth < FromWidth && isDesirableIntType(BitWidth: ToWidth))
271 return true;
272
273 // If this is a legal or desiable integer from type, and the result would be
274 // an illegal type, don't do the transformation.
275 if ((FromLegal || isDesirableIntType(BitWidth: FromWidth)) && !ToLegal)
276 return false;
277
278 // Otherwise, if both are illegal, do not increase the size of the result. We
279 // do allow things like i160 -> i64, but not i64 -> i160.
280 if (!FromLegal && !ToLegal && ToWidth > FromWidth)
281 return false;
282
283 return true;
284}
285
286/// Return true if it is desirable to convert a computation from 'From' to 'To'.
287/// We don't want to convert from a legal to an illegal type or from a smaller
288/// to a larger illegal type. i1 is always treated as a legal type because it is
289/// a fundamental type in IR, and there are many specialized optimizations for
290/// i1 types.
291bool InstCombinerImpl::shouldChangeType(Type *From, Type *To) const {
292 // TODO: This could be extended to allow vectors. Datalayout changes might be
293 // needed to properly support that.
294 if (!From->isIntegerTy() || !To->isIntegerTy())
295 return false;
296
297 unsigned FromWidth = From->getPrimitiveSizeInBits();
298 unsigned ToWidth = To->getPrimitiveSizeInBits();
299 return shouldChangeType(FromWidth, ToWidth);
300}
301
302// Return true, if No Signed Wrap should be maintained for I.
303// The No Signed Wrap flag can be kept if the operation "B (I.getOpcode) C",
304// where both B and C should be ConstantInts, results in a constant that does
305// not overflow. This function only handles the Add/Sub/Mul opcodes. For
306// all other opcodes, the function conservatively returns false.
307static bool maintainNoSignedWrap(BinaryOperator &I, Value *B, Value *C) {
308 auto *OBO = dyn_cast<OverflowingBinaryOperator>(Val: &I);
309 if (!OBO || !OBO->hasNoSignedWrap())
310 return false;
311
312 const APInt *BVal, *CVal;
313 if (!match(V: B, P: m_APInt(Res&: BVal)) || !match(V: C, P: m_APInt(Res&: CVal)))
314 return false;
315
316 // We reason about Add/Sub/Mul Only.
317 bool Overflow = false;
318 switch (I.getOpcode()) {
319 case Instruction::Add:
320 (void)BVal->sadd_ov(RHS: *CVal, Overflow);
321 break;
322 case Instruction::Sub:
323 (void)BVal->ssub_ov(RHS: *CVal, Overflow);
324 break;
325 case Instruction::Mul:
326 (void)BVal->smul_ov(RHS: *CVal, Overflow);
327 break;
328 default:
329 // Conservatively return false for other opcodes.
330 return false;
331 }
332 return !Overflow;
333}
334
335static bool hasNoUnsignedWrap(BinaryOperator &I) {
336 auto *OBO = dyn_cast<OverflowingBinaryOperator>(Val: &I);
337 return OBO && OBO->hasNoUnsignedWrap();
338}
339
340static bool hasNoSignedWrap(BinaryOperator &I) {
341 auto *OBO = dyn_cast<OverflowingBinaryOperator>(Val: &I);
342 return OBO && OBO->hasNoSignedWrap();
343}
344
345/// Conservatively clears subclassOptionalData after a reassociation or
346/// commutation. We preserve fast-math flags when applicable as they can be
347/// preserved.
348static void ClearSubclassDataAfterReassociation(BinaryOperator &I) {
349 FPMathOperator *FPMO = dyn_cast<FPMathOperator>(Val: &I);
350 if (!FPMO) {
351 I.clearSubclassOptionalData();
352 return;
353 }
354
355 FastMathFlags FMF = I.getFastMathFlags();
356 I.clearSubclassOptionalData();
357 I.setFastMathFlags(FMF);
358}
359
360/// Combine constant operands of associative operations either before or after a
361/// cast to eliminate one of the associative operations:
362/// (op (cast (op X, C2)), C1) --> (cast (op X, op (C1, C2)))
363/// (op (cast (op X, C2)), C1) --> (op (cast X), op (C1, C2))
364static bool simplifyAssocCastAssoc(BinaryOperator *BinOp1,
365 InstCombinerImpl &IC) {
366 auto *Cast = dyn_cast<CastInst>(Val: BinOp1->getOperand(i_nocapture: 0));
367 if (!Cast || !Cast->hasOneUse())
368 return false;
369
370 // TODO: Enhance logic for other casts and remove this check.
371 auto CastOpcode = Cast->getOpcode();
372 if (CastOpcode != Instruction::ZExt)
373 return false;
374
375 // TODO: Enhance logic for other BinOps and remove this check.
376 if (!BinOp1->isBitwiseLogicOp())
377 return false;
378
379 auto AssocOpcode = BinOp1->getOpcode();
380 auto *BinOp2 = dyn_cast<BinaryOperator>(Val: Cast->getOperand(i_nocapture: 0));
381 if (!BinOp2 || !BinOp2->hasOneUse() || BinOp2->getOpcode() != AssocOpcode)
382 return false;
383
384 Constant *C1, *C2;
385 if (!match(V: BinOp1->getOperand(i_nocapture: 1), P: m_Constant(C&: C1)) ||
386 !match(V: BinOp2->getOperand(i_nocapture: 1), P: m_Constant(C&: C2)))
387 return false;
388
389 // TODO: This assumes a zext cast.
390 // Eg, if it was a trunc, we'd cast C1 to the source type because casting C2
391 // to the destination type might lose bits.
392
393 // Fold the constants together in the destination type:
394 // (op (cast (op X, C2)), C1) --> (op (cast X), FoldedC)
395 const DataLayout &DL = IC.getDataLayout();
396 Type *DestTy = C1->getType();
397 Constant *CastC2 = ConstantFoldCastOperand(Opcode: CastOpcode, C: C2, DestTy, DL);
398 if (!CastC2)
399 return false;
400 Constant *FoldedC = ConstantFoldBinaryOpOperands(Opcode: AssocOpcode, LHS: C1, RHS: CastC2, DL);
401 if (!FoldedC)
402 return false;
403
404 IC.replaceOperand(I&: *Cast, OpNum: 0, V: BinOp2->getOperand(i_nocapture: 0));
405 IC.replaceOperand(I&: *BinOp1, OpNum: 1, V: FoldedC);
406 BinOp1->dropPoisonGeneratingFlags();
407 Cast->dropPoisonGeneratingFlags();
408 return true;
409}
410
411// Simplifies IntToPtr/PtrToInt RoundTrip Cast.
412// inttoptr ( ptrtoint (x) ) --> x
413Value *InstCombinerImpl::simplifyIntToPtrRoundTripCast(Value *Val) {
414 auto *IntToPtr = dyn_cast<IntToPtrInst>(Val);
415 if (IntToPtr && DL.getTypeSizeInBits(Ty: IntToPtr->getDestTy()) ==
416 DL.getTypeSizeInBits(Ty: IntToPtr->getSrcTy())) {
417 auto *PtrToInt = dyn_cast<PtrToIntInst>(Val: IntToPtr->getOperand(i_nocapture: 0));
418 Type *CastTy = IntToPtr->getDestTy();
419 if (PtrToInt &&
420 CastTy->getPointerAddressSpace() ==
421 PtrToInt->getSrcTy()->getPointerAddressSpace() &&
422 DL.getTypeSizeInBits(Ty: PtrToInt->getSrcTy()) ==
423 DL.getTypeSizeInBits(Ty: PtrToInt->getDestTy()))
424 return PtrToInt->getOperand(i_nocapture: 0);
425 }
426 return nullptr;
427}
428
429/// This performs a few simplifications for operators that are associative or
430/// commutative:
431///
432/// Commutative operators:
433///
434/// 1. Order operands such that they are listed from right (least complex) to
435/// left (most complex). This puts constants before unary operators before
436/// binary operators.
437///
438/// Associative operators:
439///
440/// 2. Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
441/// 3. Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
442///
443/// Associative and commutative operators:
444///
445/// 4. Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
446/// 5. Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
447/// 6. Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
448/// if C1 and C2 are constants.
449bool InstCombinerImpl::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
450 Instruction::BinaryOps Opcode = I.getOpcode();
451 bool Changed = false;
452
453 do {
454 // Order operands such that they are listed from right (least complex) to
455 // left (most complex). This puts constants before unary operators before
456 // binary operators.
457 if (I.isCommutative() && getComplexity(V: I.getOperand(i_nocapture: 0)) <
458 getComplexity(V: I.getOperand(i_nocapture: 1)))
459 Changed = !I.swapOperands();
460
461 if (I.isCommutative()) {
462 if (auto Pair = matchSymmetricPair(LHS: I.getOperand(i_nocapture: 0), RHS: I.getOperand(i_nocapture: 1))) {
463 replaceOperand(I, OpNum: 0, V: Pair->first);
464 replaceOperand(I, OpNum: 1, V: Pair->second);
465 Changed = true;
466 }
467 }
468
469 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(Val: I.getOperand(i_nocapture: 0));
470 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(Val: I.getOperand(i_nocapture: 1));
471
472 if (I.isAssociative()) {
473 // Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
474 if (Op0 && Op0->getOpcode() == Opcode) {
475 Value *A = Op0->getOperand(i_nocapture: 0);
476 Value *B = Op0->getOperand(i_nocapture: 1);
477 Value *C = I.getOperand(i_nocapture: 1);
478
479 // Does "B op C" simplify?
480 if (Value *V = simplifyBinOp(Opcode, LHS: B, RHS: C, Q: SQ.getWithInstruction(I: &I))) {
481 // It simplifies to V. Form "A op V".
482 replaceOperand(I, OpNum: 0, V: A);
483 replaceOperand(I, OpNum: 1, V);
484 bool IsNUW = hasNoUnsignedWrap(I) && hasNoUnsignedWrap(I&: *Op0);
485 bool IsNSW = maintainNoSignedWrap(I, B, C) && hasNoSignedWrap(I&: *Op0);
486
487 // Conservatively clear all optional flags since they may not be
488 // preserved by the reassociation. Reset nsw/nuw based on the above
489 // analysis.
490 ClearSubclassDataAfterReassociation(I);
491
492 // Note: this is only valid because SimplifyBinOp doesn't look at
493 // the operands to Op0.
494 if (IsNUW)
495 I.setHasNoUnsignedWrap(true);
496
497 if (IsNSW)
498 I.setHasNoSignedWrap(true);
499
500 Changed = true;
501 ++NumReassoc;
502 continue;
503 }
504 }
505
506 // Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
507 if (Op1 && Op1->getOpcode() == Opcode) {
508 Value *A = I.getOperand(i_nocapture: 0);
509 Value *B = Op1->getOperand(i_nocapture: 0);
510 Value *C = Op1->getOperand(i_nocapture: 1);
511
512 // Does "A op B" simplify?
513 if (Value *V = simplifyBinOp(Opcode, LHS: A, RHS: B, Q: SQ.getWithInstruction(I: &I))) {
514 // It simplifies to V. Form "V op C".
515 replaceOperand(I, OpNum: 0, V);
516 replaceOperand(I, OpNum: 1, V: C);
517 // Conservatively clear the optional flags, since they may not be
518 // preserved by the reassociation.
519 ClearSubclassDataAfterReassociation(I);
520 Changed = true;
521 ++NumReassoc;
522 continue;
523 }
524 }
525 }
526
527 if (I.isAssociative() && I.isCommutative()) {
528 if (simplifyAssocCastAssoc(BinOp1: &I, IC&: *this)) {
529 Changed = true;
530 ++NumReassoc;
531 continue;
532 }
533
534 // Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
535 if (Op0 && Op0->getOpcode() == Opcode) {
536 Value *A = Op0->getOperand(i_nocapture: 0);
537 Value *B = Op0->getOperand(i_nocapture: 1);
538 Value *C = I.getOperand(i_nocapture: 1);
539
540 // Does "C op A" simplify?
541 if (Value *V = simplifyBinOp(Opcode, LHS: C, RHS: A, Q: SQ.getWithInstruction(I: &I))) {
542 // It simplifies to V. Form "V op B".
543 replaceOperand(I, OpNum: 0, V);
544 replaceOperand(I, OpNum: 1, V: B);
545 // Conservatively clear the optional flags, since they may not be
546 // preserved by the reassociation.
547 ClearSubclassDataAfterReassociation(I);
548 Changed = true;
549 ++NumReassoc;
550 continue;
551 }
552 }
553
554 // Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
555 if (Op1 && Op1->getOpcode() == Opcode) {
556 Value *A = I.getOperand(i_nocapture: 0);
557 Value *B = Op1->getOperand(i_nocapture: 0);
558 Value *C = Op1->getOperand(i_nocapture: 1);
559
560 // Does "C op A" simplify?
561 if (Value *V = simplifyBinOp(Opcode, LHS: C, RHS: A, Q: SQ.getWithInstruction(I: &I))) {
562 // It simplifies to V. Form "B op V".
563 replaceOperand(I, OpNum: 0, V: B);
564 replaceOperand(I, OpNum: 1, V);
565 // Conservatively clear the optional flags, since they may not be
566 // preserved by the reassociation.
567 ClearSubclassDataAfterReassociation(I);
568 Changed = true;
569 ++NumReassoc;
570 continue;
571 }
572 }
573
574 // Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
575 // if C1 and C2 are constants.
576 Value *A, *B;
577 Constant *C1, *C2, *CRes;
578 if (Op0 && Op1 &&
579 Op0->getOpcode() == Opcode && Op1->getOpcode() == Opcode &&
580 match(V: Op0, P: m_OneUse(SubPattern: m_BinOp(L: m_Value(V&: A), R: m_Constant(C&: C1)))) &&
581 match(V: Op1, P: m_OneUse(SubPattern: m_BinOp(L: m_Value(V&: B), R: m_Constant(C&: C2)))) &&
582 (CRes = ConstantFoldBinaryOpOperands(Opcode, LHS: C1, RHS: C2, DL))) {
583 bool IsNUW = hasNoUnsignedWrap(I) &&
584 hasNoUnsignedWrap(I&: *Op0) &&
585 hasNoUnsignedWrap(I&: *Op1);
586 BinaryOperator *NewBO = (IsNUW && Opcode == Instruction::Add) ?
587 BinaryOperator::CreateNUW(Opc: Opcode, V1: A, V2: B) :
588 BinaryOperator::Create(Op: Opcode, S1: A, S2: B);
589
590 if (isa<FPMathOperator>(Val: NewBO)) {
591 FastMathFlags Flags = I.getFastMathFlags() &
592 Op0->getFastMathFlags() &
593 Op1->getFastMathFlags();
594 NewBO->setFastMathFlags(Flags);
595 }
596 InsertNewInstWith(New: NewBO, Old: I.getIterator());
597 NewBO->takeName(V: Op1);
598 replaceOperand(I, OpNum: 0, V: NewBO);
599 replaceOperand(I, OpNum: 1, V: CRes);
600 // Conservatively clear the optional flags, since they may not be
601 // preserved by the reassociation.
602 ClearSubclassDataAfterReassociation(I);
603 if (IsNUW)
604 I.setHasNoUnsignedWrap(true);
605
606 Changed = true;
607 continue;
608 }
609 }
610
611 // No further simplifications.
612 return Changed;
613 } while (true);
614}
615
616/// Return whether "X LOp (Y ROp Z)" is always equal to
617/// "(X LOp Y) ROp (X LOp Z)".
618static bool leftDistributesOverRight(Instruction::BinaryOps LOp,
619 Instruction::BinaryOps ROp) {
620 // X & (Y | Z) <--> (X & Y) | (X & Z)
621 // X & (Y ^ Z) <--> (X & Y) ^ (X & Z)
622 if (LOp == Instruction::And)
623 return ROp == Instruction::Or || ROp == Instruction::Xor;
624
625 // X | (Y & Z) <--> (X | Y) & (X | Z)
626 if (LOp == Instruction::Or)
627 return ROp == Instruction::And;
628
629 // X * (Y + Z) <--> (X * Y) + (X * Z)
630 // X * (Y - Z) <--> (X * Y) - (X * Z)
631 if (LOp == Instruction::Mul)
632 return ROp == Instruction::Add || ROp == Instruction::Sub;
633
634 return false;
635}
636
637/// Return whether "(X LOp Y) ROp Z" is always equal to
638/// "(X ROp Z) LOp (Y ROp Z)".
639static bool rightDistributesOverLeft(Instruction::BinaryOps LOp,
640 Instruction::BinaryOps ROp) {
641 if (Instruction::isCommutative(Opcode: ROp))
642 return leftDistributesOverRight(LOp: ROp, ROp: LOp);
643
644 // (X {&|^} Y) >> Z <--> (X >> Z) {&|^} (Y >> Z) for all shifts.
645 return Instruction::isBitwiseLogicOp(Opcode: LOp) && Instruction::isShift(Opcode: ROp);
646
647 // TODO: It would be nice to handle division, aka "(X + Y)/Z = X/Z + Y/Z",
648 // but this requires knowing that the addition does not overflow and other
649 // such subtleties.
650}
651
652/// This function returns identity value for given opcode, which can be used to
653/// factor patterns like (X * 2) + X ==> (X * 2) + (X * 1) ==> X * (2 + 1).
654static Value *getIdentityValue(Instruction::BinaryOps Opcode, Value *V) {
655 if (isa<Constant>(Val: V))
656 return nullptr;
657
658 return ConstantExpr::getBinOpIdentity(Opcode, Ty: V->getType());
659}
660
661/// This function predicates factorization using distributive laws. By default,
662/// it just returns the 'Op' inputs. But for special-cases like
663/// 'add(shl(X, 5), ...)', this function will have TopOpcode == Instruction::Add
664/// and Op = shl(X, 5). The 'shl' is treated as the more general 'mul X, 32' to
665/// allow more factorization opportunities.
666static Instruction::BinaryOps
667getBinOpsForFactorization(Instruction::BinaryOps TopOpcode, BinaryOperator *Op,
668 Value *&LHS, Value *&RHS, BinaryOperator *OtherOp) {
669 assert(Op && "Expected a binary operator");
670 LHS = Op->getOperand(i_nocapture: 0);
671 RHS = Op->getOperand(i_nocapture: 1);
672 if (TopOpcode == Instruction::Add || TopOpcode == Instruction::Sub) {
673 Constant *C;
674 if (match(V: Op, P: m_Shl(L: m_Value(), R: m_ImmConstant(C)))) {
675 // X << C --> X * (1 << C)
676 RHS = ConstantFoldBinaryInstruction(
677 Opcode: Instruction::Shl, V1: ConstantInt::get(Ty: Op->getType(), V: 1), V2: C);
678 assert(RHS && "Constant folding of immediate constants failed");
679 return Instruction::Mul;
680 }
681 // TODO: We can add other conversions e.g. shr => div etc.
682 }
683 if (Instruction::isBitwiseLogicOp(Opcode: TopOpcode)) {
684 if (OtherOp && OtherOp->getOpcode() == Instruction::AShr &&
685 match(V: Op, P: m_LShr(L: m_NonNegative(), R: m_Value()))) {
686 // lshr nneg C, X --> ashr nneg C, X
687 return Instruction::AShr;
688 }
689 }
690 return Op->getOpcode();
691}
692
693/// This tries to simplify binary operations by factorizing out common terms
694/// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
695static Value *tryFactorization(BinaryOperator &I, const SimplifyQuery &SQ,
696 InstCombiner::BuilderTy &Builder,
697 Instruction::BinaryOps InnerOpcode, Value *A,
698 Value *B, Value *C, Value *D) {
699 assert(A && B && C && D && "All values must be provided");
700
701 Value *V = nullptr;
702 Value *RetVal = nullptr;
703 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
704 Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
705
706 // Does "X op' Y" always equal "Y op' X"?
707 bool InnerCommutative = Instruction::isCommutative(Opcode: InnerOpcode);
708
709 // Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
710 if (leftDistributesOverRight(LOp: InnerOpcode, ROp: TopLevelOpcode)) {
711 // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
712 // commutative case, "(A op' B) op (C op' A)"?
713 if (A == C || (InnerCommutative && A == D)) {
714 if (A != C)
715 std::swap(a&: C, b&: D);
716 // Consider forming "A op' (B op D)".
717 // If "B op D" simplifies then it can be formed with no cost.
718 V = simplifyBinOp(Opcode: TopLevelOpcode, LHS: B, RHS: D, Q: SQ.getWithInstruction(I: &I));
719
720 // If "B op D" doesn't simplify then only go on if one of the existing
721 // operations "A op' B" and "C op' D" will be zapped as no longer used.
722 if (!V && (LHS->hasOneUse() || RHS->hasOneUse()))
723 V = Builder.CreateBinOp(Opc: TopLevelOpcode, LHS: B, RHS: D, Name: RHS->getName());
724 if (V)
725 RetVal = Builder.CreateBinOp(Opc: InnerOpcode, LHS: A, RHS: V);
726 }
727 }
728
729 // Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
730 if (!RetVal && rightDistributesOverLeft(LOp: TopLevelOpcode, ROp: InnerOpcode)) {
731 // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
732 // commutative case, "(A op' B) op (B op' D)"?
733 if (B == D || (InnerCommutative && B == C)) {
734 if (B != D)
735 std::swap(a&: C, b&: D);
736 // Consider forming "(A op C) op' B".
737 // If "A op C" simplifies then it can be formed with no cost.
738 V = simplifyBinOp(Opcode: TopLevelOpcode, LHS: A, RHS: C, Q: SQ.getWithInstruction(I: &I));
739
740 // If "A op C" doesn't simplify then only go on if one of the existing
741 // operations "A op' B" and "C op' D" will be zapped as no longer used.
742 if (!V && (LHS->hasOneUse() || RHS->hasOneUse()))
743 V = Builder.CreateBinOp(Opc: TopLevelOpcode, LHS: A, RHS: C, Name: LHS->getName());
744 if (V)
745 RetVal = Builder.CreateBinOp(Opc: InnerOpcode, LHS: V, RHS: B);
746 }
747 }
748
749 if (!RetVal)
750 return nullptr;
751
752 ++NumFactor;
753 RetVal->takeName(V: &I);
754
755 // Try to add no-overflow flags to the final value.
756 if (isa<BinaryOperator>(Val: RetVal)) {
757 bool HasNSW = false;
758 bool HasNUW = false;
759 if (isa<OverflowingBinaryOperator>(Val: &I)) {
760 HasNSW = I.hasNoSignedWrap();
761 HasNUW = I.hasNoUnsignedWrap();
762 }
763 if (auto *LOBO = dyn_cast<OverflowingBinaryOperator>(Val: LHS)) {
764 HasNSW &= LOBO->hasNoSignedWrap();
765 HasNUW &= LOBO->hasNoUnsignedWrap();
766 }
767
768 if (auto *ROBO = dyn_cast<OverflowingBinaryOperator>(Val: RHS)) {
769 HasNSW &= ROBO->hasNoSignedWrap();
770 HasNUW &= ROBO->hasNoUnsignedWrap();
771 }
772
773 if (TopLevelOpcode == Instruction::Add && InnerOpcode == Instruction::Mul) {
774 // We can propagate 'nsw' if we know that
775 // %Y = mul nsw i16 %X, C
776 // %Z = add nsw i16 %Y, %X
777 // =>
778 // %Z = mul nsw i16 %X, C+1
779 //
780 // iff C+1 isn't INT_MIN
781 const APInt *CInt;
782 if (match(V, P: m_APInt(Res&: CInt)) && !CInt->isMinSignedValue())
783 cast<Instruction>(Val: RetVal)->setHasNoSignedWrap(HasNSW);
784
785 // nuw can be propagated with any constant or nuw value.
786 cast<Instruction>(Val: RetVal)->setHasNoUnsignedWrap(HasNUW);
787 }
788 }
789 return RetVal;
790}
791
792// If `I` has one Const operand and the other matches `(ctpop (not x))`,
793// replace `(ctpop (not x))` with `(sub nuw nsw BitWidth(x), (ctpop x))`.
794// This is only useful is the new subtract can fold so we only handle the
795// following cases:
796// 1) (add/sub/disjoint_or C, (ctpop (not x))
797// -> (add/sub/disjoint_or C', (ctpop x))
798// 1) (cmp pred C, (ctpop (not x))
799// -> (cmp pred C', (ctpop x))
800Instruction *InstCombinerImpl::tryFoldInstWithCtpopWithNot(Instruction *I) {
801 unsigned Opc = I->getOpcode();
802 unsigned ConstIdx = 1;
803 switch (Opc) {
804 default:
805 return nullptr;
806 // (ctpop (not x)) <-> (sub nuw nsw BitWidth(x) - (ctpop x))
807 // We can fold the BitWidth(x) with add/sub/icmp as long the other operand
808 // is constant.
809 case Instruction::Sub:
810 ConstIdx = 0;
811 break;
812 case Instruction::ICmp:
813 // Signed predicates aren't correct in some edge cases like for i2 types, as
814 // well since (ctpop x) is known [0, log2(BitWidth(x))] almost all signed
815 // comparisons against it are simplfied to unsigned.
816 if (cast<ICmpInst>(Val: I)->isSigned())
817 return nullptr;
818 break;
819 case Instruction::Or:
820 if (!match(V: I, P: m_DisjointOr(L: m_Value(), R: m_Value())))
821 return nullptr;
822 [[fallthrough]];
823 case Instruction::Add:
824 break;
825 }
826
827 Value *Op;
828 // Find ctpop.
829 if (!match(V: I->getOperand(i: 1 - ConstIdx),
830 P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: Op)))))
831 return nullptr;
832
833 Constant *C;
834 // Check other operand is ImmConstant.
835 if (!match(V: I->getOperand(i: ConstIdx), P: m_ImmConstant(C)))
836 return nullptr;
837
838 Type *Ty = Op->getType();
839 Constant *BitWidthC = ConstantInt::get(Ty, V: Ty->getScalarSizeInBits());
840 // Need extra check for icmp. Note if this check is true, it generally means
841 // the icmp will simplify to true/false.
842 if (Opc == Instruction::ICmp && !cast<ICmpInst>(Val: I)->isEquality()) {
843 Constant *Cmp =
844 ConstantFoldCompareInstOperands(Predicate: ICmpInst::ICMP_UGT, LHS: C, RHS: BitWidthC, DL);
845 if (!Cmp || !Cmp->isZeroValue())
846 return nullptr;
847 }
848
849 // Check we can invert `(not x)` for free.
850 bool Consumes = false;
851 if (!isFreeToInvert(V: Op, WillInvertAllUses: Op->hasOneUse(), DoesConsume&: Consumes) || !Consumes)
852 return nullptr;
853 Value *NotOp = getFreelyInverted(V: Op, WillInvertAllUses: Op->hasOneUse(), Builder: &Builder);
854 assert(NotOp != nullptr &&
855 "Desync between isFreeToInvert and getFreelyInverted");
856
857 Value *CtpopOfNotOp = Builder.CreateIntrinsic(RetTy: Ty, ID: Intrinsic::ctpop, Args: NotOp);
858
859 Value *R = nullptr;
860
861 // Do the transformation here to avoid potentially introducing an infinite
862 // loop.
863 switch (Opc) {
864 case Instruction::Sub:
865 R = Builder.CreateAdd(LHS: CtpopOfNotOp, RHS: ConstantExpr::getSub(C1: C, C2: BitWidthC));
866 break;
867 case Instruction::Or:
868 case Instruction::Add:
869 R = Builder.CreateSub(LHS: ConstantExpr::getAdd(C1: C, C2: BitWidthC), RHS: CtpopOfNotOp);
870 break;
871 case Instruction::ICmp:
872 R = Builder.CreateICmp(P: cast<ICmpInst>(Val: I)->getSwappedPredicate(),
873 LHS: CtpopOfNotOp, RHS: ConstantExpr::getSub(C1: BitWidthC, C2: C));
874 break;
875 default:
876 llvm_unreachable("Unhandled Opcode");
877 }
878 assert(R != nullptr);
879 return replaceInstUsesWith(I&: *I, V: R);
880}
881
882// (Binop1 (Binop2 (logic_shift X, C), C1), (logic_shift Y, C))
883// IFF
884// 1) the logic_shifts match
885// 2) either both binops are binops and one is `and` or
886// BinOp1 is `and`
887// (logic_shift (inv_logic_shift C1, C), C) == C1 or
888//
889// -> (logic_shift (Binop1 (Binop2 X, inv_logic_shift(C1, C)), Y), C)
890//
891// (Binop1 (Binop2 (logic_shift X, Amt), Mask), (logic_shift Y, Amt))
892// IFF
893// 1) the logic_shifts match
894// 2) BinOp1 == BinOp2 (if BinOp == `add`, then also requires `shl`).
895//
896// -> (BinOp (logic_shift (BinOp X, Y)), Mask)
897//
898// (Binop1 (Binop2 (arithmetic_shift X, Amt), Mask), (arithmetic_shift Y, Amt))
899// IFF
900// 1) Binop1 is bitwise logical operator `and`, `or` or `xor`
901// 2) Binop2 is `not`
902//
903// -> (arithmetic_shift Binop1((not X), Y), Amt)
904
905Instruction *InstCombinerImpl::foldBinOpShiftWithShift(BinaryOperator &I) {
906 const DataLayout &DL = I.getDataLayout();
907 auto IsValidBinOpc = [](unsigned Opc) {
908 switch (Opc) {
909 default:
910 return false;
911 case Instruction::And:
912 case Instruction::Or:
913 case Instruction::Xor:
914 case Instruction::Add:
915 // Skip Sub as we only match constant masks which will canonicalize to use
916 // add.
917 return true;
918 }
919 };
920
921 // Check if we can distribute binop arbitrarily. `add` + `lshr` has extra
922 // constraints.
923 auto IsCompletelyDistributable = [](unsigned BinOpc1, unsigned BinOpc2,
924 unsigned ShOpc) {
925 assert(ShOpc != Instruction::AShr);
926 return (BinOpc1 != Instruction::Add && BinOpc2 != Instruction::Add) ||
927 ShOpc == Instruction::Shl;
928 };
929
930 auto GetInvShift = [](unsigned ShOpc) {
931 assert(ShOpc != Instruction::AShr);
932 return ShOpc == Instruction::LShr ? Instruction::Shl : Instruction::LShr;
933 };
934
935 auto CanDistributeBinops = [&](unsigned BinOpc1, unsigned BinOpc2,
936 unsigned ShOpc, Constant *CMask,
937 Constant *CShift) {
938 // If the BinOp1 is `and` we don't need to check the mask.
939 if (BinOpc1 == Instruction::And)
940 return true;
941
942 // For all other possible transfers we need complete distributable
943 // binop/shift (anything but `add` + `lshr`).
944 if (!IsCompletelyDistributable(BinOpc1, BinOpc2, ShOpc))
945 return false;
946
947 // If BinOp2 is `and`, any mask works (this only really helps for non-splat
948 // vecs, otherwise the mask will be simplified and the following check will
949 // handle it).
950 if (BinOpc2 == Instruction::And)
951 return true;
952
953 // Otherwise, need mask that meets the below requirement.
954 // (logic_shift (inv_logic_shift Mask, ShAmt), ShAmt) == Mask
955 Constant *MaskInvShift =
956 ConstantFoldBinaryOpOperands(Opcode: GetInvShift(ShOpc), LHS: CMask, RHS: CShift, DL);
957 return ConstantFoldBinaryOpOperands(Opcode: ShOpc, LHS: MaskInvShift, RHS: CShift, DL) ==
958 CMask;
959 };
960
961 auto MatchBinOp = [&](unsigned ShOpnum) -> Instruction * {
962 Constant *CMask, *CShift;
963 Value *X, *Y, *ShiftedX, *Mask, *Shift;
964 if (!match(V: I.getOperand(i_nocapture: ShOpnum),
965 P: m_OneUse(SubPattern: m_Shift(L: m_Value(V&: Y), R: m_Value(V&: Shift)))))
966 return nullptr;
967 if (!match(V: I.getOperand(i_nocapture: 1 - ShOpnum),
968 P: m_c_BinOp(L: m_CombineAnd(
969 L: m_OneUse(SubPattern: m_Shift(L: m_Value(V&: X), R: m_Specific(V: Shift))),
970 R: m_Value(V&: ShiftedX)),
971 R: m_Value(V&: Mask))))
972 return nullptr;
973 // Make sure we are matching instruction shifts and not ConstantExpr
974 auto *IY = dyn_cast<Instruction>(Val: I.getOperand(i_nocapture: ShOpnum));
975 auto *IX = dyn_cast<Instruction>(Val: ShiftedX);
976 if (!IY || !IX)
977 return nullptr;
978
979 // LHS and RHS need same shift opcode
980 unsigned ShOpc = IY->getOpcode();
981 if (ShOpc != IX->getOpcode())
982 return nullptr;
983
984 // Make sure binop is real instruction and not ConstantExpr
985 auto *BO2 = dyn_cast<Instruction>(Val: I.getOperand(i_nocapture: 1 - ShOpnum));
986 if (!BO2)
987 return nullptr;
988
989 unsigned BinOpc = BO2->getOpcode();
990 // Make sure we have valid binops.
991 if (!IsValidBinOpc(I.getOpcode()) || !IsValidBinOpc(BinOpc))
992 return nullptr;
993
994 if (ShOpc == Instruction::AShr) {
995 if (Instruction::isBitwiseLogicOp(Opcode: I.getOpcode()) &&
996 BinOpc == Instruction::Xor && match(V: Mask, P: m_AllOnes())) {
997 Value *NotX = Builder.CreateNot(V: X);
998 Value *NewBinOp = Builder.CreateBinOp(Opc: I.getOpcode(), LHS: Y, RHS: NotX);
999 return BinaryOperator::Create(
1000 Op: static_cast<Instruction::BinaryOps>(ShOpc), S1: NewBinOp, S2: Shift);
1001 }
1002
1003 return nullptr;
1004 }
1005
1006 // If BinOp1 == BinOp2 and it's bitwise or shl with add, then just
1007 // distribute to drop the shift irrelevant of constants.
1008 if (BinOpc == I.getOpcode() &&
1009 IsCompletelyDistributable(I.getOpcode(), BinOpc, ShOpc)) {
1010 Value *NewBinOp2 = Builder.CreateBinOp(Opc: I.getOpcode(), LHS: X, RHS: Y);
1011 Value *NewBinOp1 = Builder.CreateBinOp(
1012 Opc: static_cast<Instruction::BinaryOps>(ShOpc), LHS: NewBinOp2, RHS: Shift);
1013 return BinaryOperator::Create(Op: I.getOpcode(), S1: NewBinOp1, S2: Mask);
1014 }
1015
1016 // Otherwise we can only distribute by constant shifting the mask, so
1017 // ensure we have constants.
1018 if (!match(V: Shift, P: m_ImmConstant(C&: CShift)))
1019 return nullptr;
1020 if (!match(V: Mask, P: m_ImmConstant(C&: CMask)))
1021 return nullptr;
1022
1023 // Check if we can distribute the binops.
1024 if (!CanDistributeBinops(I.getOpcode(), BinOpc, ShOpc, CMask, CShift))
1025 return nullptr;
1026
1027 Constant *NewCMask =
1028 ConstantFoldBinaryOpOperands(Opcode: GetInvShift(ShOpc), LHS: CMask, RHS: CShift, DL);
1029 Value *NewBinOp2 = Builder.CreateBinOp(
1030 Opc: static_cast<Instruction::BinaryOps>(BinOpc), LHS: X, RHS: NewCMask);
1031 Value *NewBinOp1 = Builder.CreateBinOp(Opc: I.getOpcode(), LHS: Y, RHS: NewBinOp2);
1032 return BinaryOperator::Create(Op: static_cast<Instruction::BinaryOps>(ShOpc),
1033 S1: NewBinOp1, S2: CShift);
1034 };
1035
1036 if (Instruction *R = MatchBinOp(0))
1037 return R;
1038 return MatchBinOp(1);
1039}
1040
1041// (Binop (zext C), (select C, T, F))
1042// -> (select C, (binop 1, T), (binop 0, F))
1043//
1044// (Binop (sext C), (select C, T, F))
1045// -> (select C, (binop -1, T), (binop 0, F))
1046//
1047// Attempt to simplify binary operations into a select with folded args, when
1048// one operand of the binop is a select instruction and the other operand is a
1049// zext/sext extension, whose value is the select condition.
1050Instruction *
1051InstCombinerImpl::foldBinOpOfSelectAndCastOfSelectCondition(BinaryOperator &I) {
1052 // TODO: this simplification may be extended to any speculatable instruction,
1053 // not just binops, and would possibly be handled better in FoldOpIntoSelect.
1054 Instruction::BinaryOps Opc = I.getOpcode();
1055 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
1056 Value *A, *CondVal, *TrueVal, *FalseVal;
1057 Value *CastOp;
1058
1059 auto MatchSelectAndCast = [&](Value *CastOp, Value *SelectOp) {
1060 return match(V: CastOp, P: m_ZExtOrSExt(Op: m_Value(V&: A))) &&
1061 A->getType()->getScalarSizeInBits() == 1 &&
1062 match(V: SelectOp, P: m_Select(C: m_Value(V&: CondVal), L: m_Value(V&: TrueVal),
1063 R: m_Value(V&: FalseVal)));
1064 };
1065
1066 // Make sure one side of the binop is a select instruction, and the other is a
1067 // zero/sign extension operating on a i1.
1068 if (MatchSelectAndCast(LHS, RHS))
1069 CastOp = LHS;
1070 else if (MatchSelectAndCast(RHS, LHS))
1071 CastOp = RHS;
1072 else
1073 return nullptr;
1074
1075 auto NewFoldedConst = [&](bool IsTrueArm, Value *V) {
1076 bool IsCastOpRHS = (CastOp == RHS);
1077 bool IsZExt = isa<ZExtInst>(Val: CastOp);
1078 Constant *C;
1079
1080 if (IsTrueArm) {
1081 C = Constant::getNullValue(Ty: V->getType());
1082 } else if (IsZExt) {
1083 unsigned BitWidth = V->getType()->getScalarSizeInBits();
1084 C = Constant::getIntegerValue(Ty: V->getType(), V: APInt(BitWidth, 1));
1085 } else {
1086 C = Constant::getAllOnesValue(Ty: V->getType());
1087 }
1088
1089 return IsCastOpRHS ? Builder.CreateBinOp(Opc, LHS: V, RHS: C)
1090 : Builder.CreateBinOp(Opc, LHS: C, RHS: V);
1091 };
1092
1093 // If the value used in the zext/sext is the select condition, or the negated
1094 // of the select condition, the binop can be simplified.
1095 if (CondVal == A) {
1096 Value *NewTrueVal = NewFoldedConst(false, TrueVal);
1097 return SelectInst::Create(C: CondVal, S1: NewTrueVal,
1098 S2: NewFoldedConst(true, FalseVal));
1099 }
1100
1101 if (match(V: A, P: m_Not(V: m_Specific(V: CondVal)))) {
1102 Value *NewTrueVal = NewFoldedConst(true, TrueVal);
1103 return SelectInst::Create(C: CondVal, S1: NewTrueVal,
1104 S2: NewFoldedConst(false, FalseVal));
1105 }
1106
1107 return nullptr;
1108}
1109
1110Value *InstCombinerImpl::tryFactorizationFolds(BinaryOperator &I) {
1111 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
1112 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(Val: LHS);
1113 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(Val: RHS);
1114 Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
1115 Value *A, *B, *C, *D;
1116 Instruction::BinaryOps LHSOpcode, RHSOpcode;
1117
1118 if (Op0)
1119 LHSOpcode = getBinOpsForFactorization(TopOpcode: TopLevelOpcode, Op: Op0, LHS&: A, RHS&: B, OtherOp: Op1);
1120 if (Op1)
1121 RHSOpcode = getBinOpsForFactorization(TopOpcode: TopLevelOpcode, Op: Op1, LHS&: C, RHS&: D, OtherOp: Op0);
1122
1123 // The instruction has the form "(A op' B) op (C op' D)". Try to factorize
1124 // a common term.
1125 if (Op0 && Op1 && LHSOpcode == RHSOpcode)
1126 if (Value *V = tryFactorization(I, SQ, Builder, InnerOpcode: LHSOpcode, A, B, C, D))
1127 return V;
1128
1129 // The instruction has the form "(A op' B) op (C)". Try to factorize common
1130 // term.
1131 if (Op0)
1132 if (Value *Ident = getIdentityValue(Opcode: LHSOpcode, V: RHS))
1133 if (Value *V =
1134 tryFactorization(I, SQ, Builder, InnerOpcode: LHSOpcode, A, B, C: RHS, D: Ident))
1135 return V;
1136
1137 // The instruction has the form "(B) op (C op' D)". Try to factorize common
1138 // term.
1139 if (Op1)
1140 if (Value *Ident = getIdentityValue(Opcode: RHSOpcode, V: LHS))
1141 if (Value *V =
1142 tryFactorization(I, SQ, Builder, InnerOpcode: RHSOpcode, A: LHS, B: Ident, C, D))
1143 return V;
1144
1145 return nullptr;
1146}
1147
1148/// This tries to simplify binary operations which some other binary operation
1149/// distributes over either by factorizing out common terms
1150/// (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this results in
1151/// simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is a win).
1152/// Returns the simplified value, or null if it didn't simplify.
1153Value *InstCombinerImpl::foldUsingDistributiveLaws(BinaryOperator &I) {
1154 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
1155 BinaryOperator *Op0 = dyn_cast<BinaryOperator>(Val: LHS);
1156 BinaryOperator *Op1 = dyn_cast<BinaryOperator>(Val: RHS);
1157 Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
1158
1159 // Factorization.
1160 if (Value *R = tryFactorizationFolds(I))
1161 return R;
1162
1163 // Expansion.
1164 if (Op0 && rightDistributesOverLeft(LOp: Op0->getOpcode(), ROp: TopLevelOpcode)) {
1165 // The instruction has the form "(A op' B) op C". See if expanding it out
1166 // to "(A op C) op' (B op C)" results in simplifications.
1167 Value *A = Op0->getOperand(i_nocapture: 0), *B = Op0->getOperand(i_nocapture: 1), *C = RHS;
1168 Instruction::BinaryOps InnerOpcode = Op0->getOpcode(); // op'
1169
1170 // Disable the use of undef because it's not safe to distribute undef.
1171 auto SQDistributive = SQ.getWithInstruction(I: &I).getWithoutUndef();
1172 Value *L = simplifyBinOp(Opcode: TopLevelOpcode, LHS: A, RHS: C, Q: SQDistributive);
1173 Value *R = simplifyBinOp(Opcode: TopLevelOpcode, LHS: B, RHS: C, Q: SQDistributive);
1174
1175 // Do "A op C" and "B op C" both simplify?
1176 if (L && R) {
1177 // They do! Return "L op' R".
1178 ++NumExpand;
1179 C = Builder.CreateBinOp(Opc: InnerOpcode, LHS: L, RHS: R);
1180 C->takeName(V: &I);
1181 return C;
1182 }
1183
1184 // Does "A op C" simplify to the identity value for the inner opcode?
1185 if (L && L == ConstantExpr::getBinOpIdentity(Opcode: InnerOpcode, Ty: L->getType())) {
1186 // They do! Return "B op C".
1187 ++NumExpand;
1188 C = Builder.CreateBinOp(Opc: TopLevelOpcode, LHS: B, RHS: C);
1189 C->takeName(V: &I);
1190 return C;
1191 }
1192
1193 // Does "B op C" simplify to the identity value for the inner opcode?
1194 if (R && R == ConstantExpr::getBinOpIdentity(Opcode: InnerOpcode, Ty: R->getType())) {
1195 // They do! Return "A op C".
1196 ++NumExpand;
1197 C = Builder.CreateBinOp(Opc: TopLevelOpcode, LHS: A, RHS: C);
1198 C->takeName(V: &I);
1199 return C;
1200 }
1201 }
1202
1203 if (Op1 && leftDistributesOverRight(LOp: TopLevelOpcode, ROp: Op1->getOpcode())) {
1204 // The instruction has the form "A op (B op' C)". See if expanding it out
1205 // to "(A op B) op' (A op C)" results in simplifications.
1206 Value *A = LHS, *B = Op1->getOperand(i_nocapture: 0), *C = Op1->getOperand(i_nocapture: 1);
1207 Instruction::BinaryOps InnerOpcode = Op1->getOpcode(); // op'
1208
1209 // Disable the use of undef because it's not safe to distribute undef.
1210 auto SQDistributive = SQ.getWithInstruction(I: &I).getWithoutUndef();
1211 Value *L = simplifyBinOp(Opcode: TopLevelOpcode, LHS: A, RHS: B, Q: SQDistributive);
1212 Value *R = simplifyBinOp(Opcode: TopLevelOpcode, LHS: A, RHS: C, Q: SQDistributive);
1213
1214 // Do "A op B" and "A op C" both simplify?
1215 if (L && R) {
1216 // They do! Return "L op' R".
1217 ++NumExpand;
1218 A = Builder.CreateBinOp(Opc: InnerOpcode, LHS: L, RHS: R);
1219 A->takeName(V: &I);
1220 return A;
1221 }
1222
1223 // Does "A op B" simplify to the identity value for the inner opcode?
1224 if (L && L == ConstantExpr::getBinOpIdentity(Opcode: InnerOpcode, Ty: L->getType())) {
1225 // They do! Return "A op C".
1226 ++NumExpand;
1227 A = Builder.CreateBinOp(Opc: TopLevelOpcode, LHS: A, RHS: C);
1228 A->takeName(V: &I);
1229 return A;
1230 }
1231
1232 // Does "A op C" simplify to the identity value for the inner opcode?
1233 if (R && R == ConstantExpr::getBinOpIdentity(Opcode: InnerOpcode, Ty: R->getType())) {
1234 // They do! Return "A op B".
1235 ++NumExpand;
1236 A = Builder.CreateBinOp(Opc: TopLevelOpcode, LHS: A, RHS: B);
1237 A->takeName(V: &I);
1238 return A;
1239 }
1240 }
1241
1242 return SimplifySelectsFeedingBinaryOp(I, LHS, RHS);
1243}
1244
1245static std::optional<std::pair<Value *, Value *>>
1246matchSymmetricPhiNodesPair(PHINode *LHS, PHINode *RHS) {
1247 if (LHS->getParent() != RHS->getParent())
1248 return std::nullopt;
1249
1250 if (LHS->getNumIncomingValues() < 2)
1251 return std::nullopt;
1252
1253 if (!equal(LRange: LHS->blocks(), RRange: RHS->blocks()))
1254 return std::nullopt;
1255
1256 Value *L0 = LHS->getIncomingValue(i: 0);
1257 Value *R0 = RHS->getIncomingValue(i: 0);
1258
1259 for (unsigned I = 1, E = LHS->getNumIncomingValues(); I != E; ++I) {
1260 Value *L1 = LHS->getIncomingValue(i: I);
1261 Value *R1 = RHS->getIncomingValue(i: I);
1262
1263 if ((L0 == L1 && R0 == R1) || (L0 == R1 && R0 == L1))
1264 continue;
1265
1266 return std::nullopt;
1267 }
1268
1269 return std::optional(std::pair(L0, R0));
1270}
1271
1272std::optional<std::pair<Value *, Value *>>
1273InstCombinerImpl::matchSymmetricPair(Value *LHS, Value *RHS) {
1274 Instruction *LHSInst = dyn_cast<Instruction>(Val: LHS);
1275 Instruction *RHSInst = dyn_cast<Instruction>(Val: RHS);
1276 if (!LHSInst || !RHSInst || LHSInst->getOpcode() != RHSInst->getOpcode())
1277 return std::nullopt;
1278 switch (LHSInst->getOpcode()) {
1279 case Instruction::PHI:
1280 return matchSymmetricPhiNodesPair(LHS: cast<PHINode>(Val: LHS), RHS: cast<PHINode>(Val: RHS));
1281 case Instruction::Select: {
1282 Value *Cond = LHSInst->getOperand(i: 0);
1283 Value *TrueVal = LHSInst->getOperand(i: 1);
1284 Value *FalseVal = LHSInst->getOperand(i: 2);
1285 if (Cond == RHSInst->getOperand(i: 0) && TrueVal == RHSInst->getOperand(i: 2) &&
1286 FalseVal == RHSInst->getOperand(i: 1))
1287 return std::pair(TrueVal, FalseVal);
1288 return std::nullopt;
1289 }
1290 case Instruction::Call: {
1291 // Match min(a, b) and max(a, b)
1292 MinMaxIntrinsic *LHSMinMax = dyn_cast<MinMaxIntrinsic>(Val: LHSInst);
1293 MinMaxIntrinsic *RHSMinMax = dyn_cast<MinMaxIntrinsic>(Val: RHSInst);
1294 if (LHSMinMax && RHSMinMax &&
1295 LHSMinMax->getPredicate() ==
1296 ICmpInst::getSwappedPredicate(pred: RHSMinMax->getPredicate()) &&
1297 ((LHSMinMax->getLHS() == RHSMinMax->getLHS() &&
1298 LHSMinMax->getRHS() == RHSMinMax->getRHS()) ||
1299 (LHSMinMax->getLHS() == RHSMinMax->getRHS() &&
1300 LHSMinMax->getRHS() == RHSMinMax->getLHS())))
1301 return std::pair(LHSMinMax->getLHS(), LHSMinMax->getRHS());
1302 return std::nullopt;
1303 }
1304 default:
1305 return std::nullopt;
1306 }
1307}
1308
1309Value *InstCombinerImpl::SimplifySelectsFeedingBinaryOp(BinaryOperator &I,
1310 Value *LHS,
1311 Value *RHS) {
1312 Value *A, *B, *C, *D, *E, *F;
1313 bool LHSIsSelect = match(V: LHS, P: m_Select(C: m_Value(V&: A), L: m_Value(V&: B), R: m_Value(V&: C)));
1314 bool RHSIsSelect = match(V: RHS, P: m_Select(C: m_Value(V&: D), L: m_Value(V&: E), R: m_Value(V&: F)));
1315 if (!LHSIsSelect && !RHSIsSelect)
1316 return nullptr;
1317
1318 FastMathFlags FMF;
1319 BuilderTy::FastMathFlagGuard Guard(Builder);
1320 if (isa<FPMathOperator>(Val: &I)) {
1321 FMF = I.getFastMathFlags();
1322 Builder.setFastMathFlags(FMF);
1323 }
1324
1325 Instruction::BinaryOps Opcode = I.getOpcode();
1326 SimplifyQuery Q = SQ.getWithInstruction(I: &I);
1327
1328 Value *Cond, *True = nullptr, *False = nullptr;
1329
1330 // Special-case for add/negate combination. Replace the zero in the negation
1331 // with the trailing add operand:
1332 // (Cond ? TVal : -N) + Z --> Cond ? True : (Z - N)
1333 // (Cond ? -N : FVal) + Z --> Cond ? (Z - N) : False
1334 auto foldAddNegate = [&](Value *TVal, Value *FVal, Value *Z) -> Value * {
1335 // We need an 'add' and exactly 1 arm of the select to have been simplified.
1336 if (Opcode != Instruction::Add || (!True && !False) || (True && False))
1337 return nullptr;
1338
1339 Value *N;
1340 if (True && match(V: FVal, P: m_Neg(V: m_Value(V&: N)))) {
1341 Value *Sub = Builder.CreateSub(LHS: Z, RHS: N);
1342 return Builder.CreateSelect(C: Cond, True, False: Sub, Name: I.getName());
1343 }
1344 if (False && match(V: TVal, P: m_Neg(V: m_Value(V&: N)))) {
1345 Value *Sub = Builder.CreateSub(LHS: Z, RHS: N);
1346 return Builder.CreateSelect(C: Cond, True: Sub, False, Name: I.getName());
1347 }
1348 return nullptr;
1349 };
1350
1351 if (LHSIsSelect && RHSIsSelect && A == D) {
1352 // (A ? B : C) op (A ? E : F) -> A ? (B op E) : (C op F)
1353 Cond = A;
1354 True = simplifyBinOp(Opcode, LHS: B, RHS: E, FMF, Q);
1355 False = simplifyBinOp(Opcode, LHS: C, RHS: F, FMF, Q);
1356
1357 if (LHS->hasOneUse() && RHS->hasOneUse()) {
1358 if (False && !True)
1359 True = Builder.CreateBinOp(Opc: Opcode, LHS: B, RHS: E);
1360 else if (True && !False)
1361 False = Builder.CreateBinOp(Opc: Opcode, LHS: C, RHS: F);
1362 }
1363 } else if (LHSIsSelect && LHS->hasOneUse()) {
1364 // (A ? B : C) op Y -> A ? (B op Y) : (C op Y)
1365 Cond = A;
1366 True = simplifyBinOp(Opcode, LHS: B, RHS, FMF, Q);
1367 False = simplifyBinOp(Opcode, LHS: C, RHS, FMF, Q);
1368 if (Value *NewSel = foldAddNegate(B, C, RHS))
1369 return NewSel;
1370 } else if (RHSIsSelect && RHS->hasOneUse()) {
1371 // X op (D ? E : F) -> D ? (X op E) : (X op F)
1372 Cond = D;
1373 True = simplifyBinOp(Opcode, LHS, RHS: E, FMF, Q);
1374 False = simplifyBinOp(Opcode, LHS, RHS: F, FMF, Q);
1375 if (Value *NewSel = foldAddNegate(E, F, LHS))
1376 return NewSel;
1377 }
1378
1379 if (!True || !False)
1380 return nullptr;
1381
1382 Value *SI = Builder.CreateSelect(C: Cond, True, False);
1383 SI->takeName(V: &I);
1384 return SI;
1385}
1386
1387/// Freely adapt every user of V as-if V was changed to !V.
1388/// WARNING: only if canFreelyInvertAllUsersOf() said this can be done.
1389void InstCombinerImpl::freelyInvertAllUsersOf(Value *I, Value *IgnoredUser) {
1390 assert(!isa<Constant>(I) && "Shouldn't invert users of constant");
1391 for (User *U : make_early_inc_range(Range: I->users())) {
1392 if (U == IgnoredUser)
1393 continue; // Don't consider this user.
1394 switch (cast<Instruction>(Val: U)->getOpcode()) {
1395 case Instruction::Select: {
1396 auto *SI = cast<SelectInst>(Val: U);
1397 SI->swapValues();
1398 SI->swapProfMetadata();
1399 break;
1400 }
1401 case Instruction::Br: {
1402 BranchInst *BI = cast<BranchInst>(Val: U);
1403 BI->swapSuccessors(); // swaps prof metadata too
1404 if (BPI)
1405 BPI->swapSuccEdgesProbabilities(Src: BI->getParent());
1406 break;
1407 }
1408 case Instruction::Xor:
1409 replaceInstUsesWith(I&: cast<Instruction>(Val&: *U), V: I);
1410 // Add to worklist for DCE.
1411 addToWorklist(I: cast<Instruction>(Val: U));
1412 break;
1413 default:
1414 llvm_unreachable("Got unexpected user - out of sync with "
1415 "canFreelyInvertAllUsersOf() ?");
1416 }
1417 }
1418
1419 // Update pre-existing debug value uses.
1420 SmallVector<DbgValueInst *, 4> DbgValues;
1421 SmallVector<DbgVariableRecord *, 4> DbgVariableRecords;
1422 llvm::findDbgValues(DbgValues, V: I, DbgVariableRecords: &DbgVariableRecords);
1423
1424 auto InvertDbgValueUse = [&](auto *DbgVal) {
1425 SmallVector<uint64_t, 1> Ops = {dwarf::DW_OP_not};
1426 for (unsigned Idx = 0, End = DbgVal->getNumVariableLocationOps();
1427 Idx != End; ++Idx)
1428 if (DbgVal->getVariableLocationOp(Idx) == I)
1429 DbgVal->setExpression(
1430 DIExpression::appendOpsToArg(Expr: DbgVal->getExpression(), Ops, ArgNo: Idx));
1431 };
1432
1433 for (DbgValueInst *DVI : DbgValues)
1434 InvertDbgValueUse(DVI);
1435
1436 for (DbgVariableRecord *DVR : DbgVariableRecords)
1437 InvertDbgValueUse(DVR);
1438}
1439
1440/// Given a 'sub' instruction, return the RHS of the instruction if the LHS is a
1441/// constant zero (which is the 'negate' form).
1442Value *InstCombinerImpl::dyn_castNegVal(Value *V) const {
1443 Value *NegV;
1444 if (match(V, P: m_Neg(V: m_Value(V&: NegV))))
1445 return NegV;
1446
1447 // Constants can be considered to be negated values if they can be folded.
1448 if (ConstantInt *C = dyn_cast<ConstantInt>(Val: V))
1449 return ConstantExpr::getNeg(C);
1450
1451 if (ConstantDataVector *C = dyn_cast<ConstantDataVector>(Val: V))
1452 if (C->getType()->getElementType()->isIntegerTy())
1453 return ConstantExpr::getNeg(C);
1454
1455 if (ConstantVector *CV = dyn_cast<ConstantVector>(Val: V)) {
1456 for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
1457 Constant *Elt = CV->getAggregateElement(Elt: i);
1458 if (!Elt)
1459 return nullptr;
1460
1461 if (isa<UndefValue>(Val: Elt))
1462 continue;
1463
1464 if (!isa<ConstantInt>(Val: Elt))
1465 return nullptr;
1466 }
1467 return ConstantExpr::getNeg(C: CV);
1468 }
1469
1470 // Negate integer vector splats.
1471 if (auto *CV = dyn_cast<Constant>(Val: V))
1472 if (CV->getType()->isVectorTy() &&
1473 CV->getType()->getScalarType()->isIntegerTy() && CV->getSplatValue())
1474 return ConstantExpr::getNeg(C: CV);
1475
1476 return nullptr;
1477}
1478
1479// Try to fold:
1480// 1) (fp_binop ({s|u}itofp x), ({s|u}itofp y))
1481// -> ({s|u}itofp (int_binop x, y))
1482// 2) (fp_binop ({s|u}itofp x), FpC)
1483// -> ({s|u}itofp (int_binop x, (fpto{s|u}i FpC)))
1484//
1485// Assuming the sign of the cast for x/y is `OpsFromSigned`.
1486Instruction *InstCombinerImpl::foldFBinOpOfIntCastsFromSign(
1487 BinaryOperator &BO, bool OpsFromSigned, std::array<Value *, 2> IntOps,
1488 Constant *Op1FpC, SmallVectorImpl<WithCache<const Value *>> &OpsKnown) {
1489
1490 Type *FPTy = BO.getType();
1491 Type *IntTy = IntOps[0]->getType();
1492
1493 unsigned IntSz = IntTy->getScalarSizeInBits();
1494 // This is the maximum number of inuse bits by the integer where the int -> fp
1495 // casts are exact.
1496 unsigned MaxRepresentableBits =
1497 APFloat::semanticsPrecision(FPTy->getScalarType()->getFltSemantics());
1498
1499 // Preserve known number of leading bits. This can allow us to trivial nsw/nuw
1500 // checks later on.
1501 unsigned NumUsedLeadingBits[2] = {IntSz, IntSz};
1502
1503 // NB: This only comes up if OpsFromSigned is true, so there is no need to
1504 // cache if between calls to `foldFBinOpOfIntCastsFromSign`.
1505 auto IsNonZero = [&](unsigned OpNo) -> bool {
1506 if (OpsKnown[OpNo].hasKnownBits() &&
1507 OpsKnown[OpNo].getKnownBits(Q: SQ).isNonZero())
1508 return true;
1509 return isKnownNonZero(V: IntOps[OpNo], Q: SQ);
1510 };
1511
1512 auto IsNonNeg = [&](unsigned OpNo) -> bool {
1513 // NB: This matches the impl in ValueTracking, we just try to use cached
1514 // knownbits here. If we ever start supporting WithCache for
1515 // `isKnownNonNegative`, change this to an explicit call.
1516 return OpsKnown[OpNo].getKnownBits(Q: SQ).isNonNegative();
1517 };
1518
1519 // Check if we know for certain that ({s|u}itofp op) is exact.
1520 auto IsValidPromotion = [&](unsigned OpNo) -> bool {
1521 // Can we treat this operand as the desired sign?
1522 if (OpsFromSigned != isa<SIToFPInst>(Val: BO.getOperand(i_nocapture: OpNo)) &&
1523 !IsNonNeg(OpNo))
1524 return false;
1525
1526 // If fp precision >= bitwidth(op) then its exact.
1527 // NB: This is slightly conservative for `sitofp`. For signed conversion, we
1528 // can handle `MaxRepresentableBits == IntSz - 1` as the sign bit will be
1529 // handled specially. We can't, however, increase the bound arbitrarily for
1530 // `sitofp` as for larger sizes, it won't sign extend.
1531 if (MaxRepresentableBits < IntSz) {
1532 // Otherwise if its signed cast check that fp precisions >= bitwidth(op) -
1533 // numSignBits(op).
1534 // TODO: If we add support for `WithCache` in `ComputeNumSignBits`, change
1535 // `IntOps[OpNo]` arguments to `KnownOps[OpNo]`.
1536 if (OpsFromSigned)
1537 NumUsedLeadingBits[OpNo] = IntSz - ComputeNumSignBits(Op: IntOps[OpNo]);
1538 // Finally for unsigned check that fp precision >= bitwidth(op) -
1539 // numLeadingZeros(op).
1540 else {
1541 NumUsedLeadingBits[OpNo] =
1542 IntSz - OpsKnown[OpNo].getKnownBits(Q: SQ).countMinLeadingZeros();
1543 }
1544 }
1545 // NB: We could also check if op is known to be a power of 2 or zero (which
1546 // will always be representable). Its unlikely, however, that is we are
1547 // unable to bound op in any way we will be able to pass the overflow checks
1548 // later on.
1549
1550 if (MaxRepresentableBits < NumUsedLeadingBits[OpNo])
1551 return false;
1552 // Signed + Mul also requires that op is non-zero to avoid -0 cases.
1553 return !OpsFromSigned || BO.getOpcode() != Instruction::FMul ||
1554 IsNonZero(OpNo);
1555 };
1556
1557 // If we have a constant rhs, see if we can losslessly convert it to an int.
1558 if (Op1FpC != nullptr) {
1559 // Signed + Mul req non-zero
1560 if (OpsFromSigned && BO.getOpcode() == Instruction::FMul &&
1561 !match(V: Op1FpC, P: m_NonZeroFP()))
1562 return nullptr;
1563
1564 Constant *Op1IntC = ConstantFoldCastOperand(
1565 Opcode: OpsFromSigned ? Instruction::FPToSI : Instruction::FPToUI, C: Op1FpC,
1566 DestTy: IntTy, DL);
1567 if (Op1IntC == nullptr)
1568 return nullptr;
1569 if (ConstantFoldCastOperand(Opcode: OpsFromSigned ? Instruction::SIToFP
1570 : Instruction::UIToFP,
1571 C: Op1IntC, DestTy: FPTy, DL) != Op1FpC)
1572 return nullptr;
1573
1574 // First try to keep sign of cast the same.
1575 IntOps[1] = Op1IntC;
1576 }
1577
1578 // Ensure lhs/rhs integer types match.
1579 if (IntTy != IntOps[1]->getType())
1580 return nullptr;
1581
1582 if (Op1FpC == nullptr) {
1583 if (!IsValidPromotion(1))
1584 return nullptr;
1585 }
1586 if (!IsValidPromotion(0))
1587 return nullptr;
1588
1589 // Final we check if the integer version of the binop will not overflow.
1590 BinaryOperator::BinaryOps IntOpc;
1591 // Because of the precision check, we can often rule out overflows.
1592 bool NeedsOverflowCheck = true;
1593 // Try to conservatively rule out overflow based on the already done precision
1594 // checks.
1595 unsigned OverflowMaxOutputBits = OpsFromSigned ? 2 : 1;
1596 unsigned OverflowMaxCurBits =
1597 std::max(a: NumUsedLeadingBits[0], b: NumUsedLeadingBits[1]);
1598 bool OutputSigned = OpsFromSigned;
1599 switch (BO.getOpcode()) {
1600 case Instruction::FAdd:
1601 IntOpc = Instruction::Add;
1602 OverflowMaxOutputBits += OverflowMaxCurBits;
1603 break;
1604 case Instruction::FSub:
1605 IntOpc = Instruction::Sub;
1606 OverflowMaxOutputBits += OverflowMaxCurBits;
1607 break;
1608 case Instruction::FMul:
1609 IntOpc = Instruction::Mul;
1610 OverflowMaxOutputBits += OverflowMaxCurBits * 2;
1611 break;
1612 default:
1613 llvm_unreachable("Unsupported binop");
1614 }
1615 // The precision check may have already ruled out overflow.
1616 if (OverflowMaxOutputBits < IntSz) {
1617 NeedsOverflowCheck = false;
1618 // We can bound unsigned overflow from sub to in range signed value (this is
1619 // what allows us to avoid the overflow check for sub).
1620 if (IntOpc == Instruction::Sub)
1621 OutputSigned = true;
1622 }
1623
1624 // Precision check did not rule out overflow, so need to check.
1625 // TODO: If we add support for `WithCache` in `willNotOverflow`, change
1626 // `IntOps[...]` arguments to `KnownOps[...]`.
1627 if (NeedsOverflowCheck &&
1628 !willNotOverflow(Opcode: IntOpc, LHS: IntOps[0], RHS: IntOps[1], CxtI: BO, IsSigned: OutputSigned))
1629 return nullptr;
1630
1631 Value *IntBinOp = Builder.CreateBinOp(Opc: IntOpc, LHS: IntOps[0], RHS: IntOps[1]);
1632 if (auto *IntBO = dyn_cast<BinaryOperator>(Val: IntBinOp)) {
1633 IntBO->setHasNoSignedWrap(OutputSigned);
1634 IntBO->setHasNoUnsignedWrap(!OutputSigned);
1635 }
1636 if (OutputSigned)
1637 return new SIToFPInst(IntBinOp, FPTy);
1638 return new UIToFPInst(IntBinOp, FPTy);
1639}
1640
1641// Try to fold:
1642// 1) (fp_binop ({s|u}itofp x), ({s|u}itofp y))
1643// -> ({s|u}itofp (int_binop x, y))
1644// 2) (fp_binop ({s|u}itofp x), FpC)
1645// -> ({s|u}itofp (int_binop x, (fpto{s|u}i FpC)))
1646Instruction *InstCombinerImpl::foldFBinOpOfIntCasts(BinaryOperator &BO) {
1647 std::array<Value *, 2> IntOps = {nullptr, nullptr};
1648 Constant *Op1FpC = nullptr;
1649 // Check for:
1650 // 1) (binop ({s|u}itofp x), ({s|u}itofp y))
1651 // 2) (binop ({s|u}itofp x), FpC)
1652 if (!match(V: BO.getOperand(i_nocapture: 0), P: m_SIToFP(Op: m_Value(V&: IntOps[0]))) &&
1653 !match(V: BO.getOperand(i_nocapture: 0), P: m_UIToFP(Op: m_Value(V&: IntOps[0]))))
1654 return nullptr;
1655
1656 if (!match(V: BO.getOperand(i_nocapture: 1), P: m_Constant(C&: Op1FpC)) &&
1657 !match(V: BO.getOperand(i_nocapture: 1), P: m_SIToFP(Op: m_Value(V&: IntOps[1]))) &&
1658 !match(V: BO.getOperand(i_nocapture: 1), P: m_UIToFP(Op: m_Value(V&: IntOps[1]))))
1659 return nullptr;
1660
1661 // Cache KnownBits a bit to potentially save some analysis.
1662 SmallVector<WithCache<const Value *>, 2> OpsKnown = {IntOps[0], IntOps[1]};
1663
1664 // Try treating x/y as coming from both `uitofp` and `sitofp`. There are
1665 // different constraints depending on the sign of the cast.
1666 // NB: `(uitofp nneg X)` == `(sitofp nneg X)`.
1667 if (Instruction *R = foldFBinOpOfIntCastsFromSign(BO, /*OpsFromSigned=*/false,
1668 IntOps, Op1FpC, OpsKnown))
1669 return R;
1670 return foldFBinOpOfIntCastsFromSign(BO, /*OpsFromSigned=*/true, IntOps,
1671 Op1FpC, OpsKnown);
1672}
1673
1674/// A binop with a constant operand and a sign-extended boolean operand may be
1675/// converted into a select of constants by applying the binary operation to
1676/// the constant with the two possible values of the extended boolean (0 or -1).
1677Instruction *InstCombinerImpl::foldBinopOfSextBoolToSelect(BinaryOperator &BO) {
1678 // TODO: Handle non-commutative binop (constant is operand 0).
1679 // TODO: Handle zext.
1680 // TODO: Peek through 'not' of cast.
1681 Value *BO0 = BO.getOperand(i_nocapture: 0);
1682 Value *BO1 = BO.getOperand(i_nocapture: 1);
1683 Value *X;
1684 Constant *C;
1685 if (!match(V: BO0, P: m_SExt(Op: m_Value(V&: X))) || !match(V: BO1, P: m_ImmConstant(C)) ||
1686 !X->getType()->isIntOrIntVectorTy(BitWidth: 1))
1687 return nullptr;
1688
1689 // bo (sext i1 X), C --> select X, (bo -1, C), (bo 0, C)
1690 Constant *Ones = ConstantInt::getAllOnesValue(Ty: BO.getType());
1691 Constant *Zero = ConstantInt::getNullValue(Ty: BO.getType());
1692 Value *TVal = Builder.CreateBinOp(Opc: BO.getOpcode(), LHS: Ones, RHS: C);
1693 Value *FVal = Builder.CreateBinOp(Opc: BO.getOpcode(), LHS: Zero, RHS: C);
1694 return SelectInst::Create(C: X, S1: TVal, S2: FVal);
1695}
1696
1697static Value *simplifyOperationIntoSelectOperand(Instruction &I, SelectInst *SI,
1698 bool IsTrueArm) {
1699 SmallVector<Value *> Ops;
1700 for (Value *Op : I.operands()) {
1701 Value *V = nullptr;
1702 if (Op == SI) {
1703 V = IsTrueArm ? SI->getTrueValue() : SI->getFalseValue();
1704 } else if (match(V: SI->getCondition(),
1705 P: m_SpecificICmp(MatchPred: IsTrueArm ? ICmpInst::ICMP_EQ
1706 : ICmpInst::ICMP_NE,
1707 L: m_Specific(V: Op), R: m_Value(V))) &&
1708 isGuaranteedNotToBeUndefOrPoison(V)) {
1709 // Pass
1710 } else {
1711 V = Op;
1712 }
1713 Ops.push_back(Elt: V);
1714 }
1715
1716 return simplifyInstructionWithOperands(I: &I, NewOps: Ops, Q: I.getDataLayout());
1717}
1718
1719static Value *foldOperationIntoSelectOperand(Instruction &I, SelectInst *SI,
1720 Value *NewOp, InstCombiner &IC) {
1721 Instruction *Clone = I.clone();
1722 Clone->replaceUsesOfWith(From: SI, To: NewOp);
1723 Clone->dropUBImplyingAttrsAndMetadata();
1724 IC.InsertNewInstBefore(New: Clone, Old: I.getIterator());
1725 return Clone;
1726}
1727
1728Instruction *InstCombinerImpl::FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
1729 bool FoldWithMultiUse) {
1730 // Don't modify shared select instructions unless set FoldWithMultiUse
1731 if (!SI->hasOneUse() && !FoldWithMultiUse)
1732 return nullptr;
1733
1734 Value *TV = SI->getTrueValue();
1735 Value *FV = SI->getFalseValue();
1736
1737 // Bool selects with constant operands can be folded to logical ops.
1738 if (SI->getType()->isIntOrIntVectorTy(BitWidth: 1))
1739 return nullptr;
1740
1741 // Avoid breaking min/max reduction pattern,
1742 // which is necessary for vectorization later.
1743 if (isa<MinMaxIntrinsic>(Val: &Op))
1744 for (Value *IntrinOp : Op.operands())
1745 if (auto *PN = dyn_cast<PHINode>(Val: IntrinOp))
1746 for (Value *PhiOp : PN->operands())
1747 if (PhiOp == &Op)
1748 return nullptr;
1749
1750 // Test if a FCmpInst instruction is used exclusively by a select as
1751 // part of a minimum or maximum operation. If so, refrain from doing
1752 // any other folding. This helps out other analyses which understand
1753 // non-obfuscated minimum and maximum idioms. And in this case, at
1754 // least one of the comparison operands has at least one user besides
1755 // the compare (the select), which would often largely negate the
1756 // benefit of folding anyway.
1757 if (auto *CI = dyn_cast<FCmpInst>(Val: SI->getCondition())) {
1758 if (CI->hasOneUse()) {
1759 Value *Op0 = CI->getOperand(i_nocapture: 0), *Op1 = CI->getOperand(i_nocapture: 1);
1760 if (((TV == Op0 && FV == Op1) || (FV == Op0 && TV == Op1)) &&
1761 !CI->isCommutative())
1762 return nullptr;
1763 }
1764 }
1765
1766 // Make sure that one of the select arms folds successfully.
1767 Value *NewTV = simplifyOperationIntoSelectOperand(I&: Op, SI, /*IsTrueArm=*/true);
1768 Value *NewFV =
1769 simplifyOperationIntoSelectOperand(I&: Op, SI, /*IsTrueArm=*/false);
1770 if (!NewTV && !NewFV)
1771 return nullptr;
1772
1773 // Create an instruction for the arm that did not fold.
1774 if (!NewTV)
1775 NewTV = foldOperationIntoSelectOperand(I&: Op, SI, NewOp: TV, IC&: *this);
1776 if (!NewFV)
1777 NewFV = foldOperationIntoSelectOperand(I&: Op, SI, NewOp: FV, IC&: *this);
1778 return SelectInst::Create(C: SI->getCondition(), S1: NewTV, S2: NewFV, NameStr: "", InsertBefore: nullptr, MDFrom: SI);
1779}
1780
1781static Value *simplifyInstructionWithPHI(Instruction &I, PHINode *PN,
1782 Value *InValue, BasicBlock *InBB,
1783 const DataLayout &DL,
1784 const SimplifyQuery SQ) {
1785 // NB: It is a precondition of this transform that the operands be
1786 // phi translatable!
1787 SmallVector<Value *> Ops;
1788 for (Value *Op : I.operands()) {
1789 if (Op == PN)
1790 Ops.push_back(Elt: InValue);
1791 else
1792 Ops.push_back(Elt: Op->DoPHITranslation(CurBB: PN->getParent(), PredBB: InBB));
1793 }
1794
1795 // Don't consider the simplification successful if we get back a constant
1796 // expression. That's just an instruction in hiding.
1797 // Also reject the case where we simplify back to the phi node. We wouldn't
1798 // be able to remove it in that case.
1799 Value *NewVal = simplifyInstructionWithOperands(
1800 I: &I, NewOps: Ops, Q: SQ.getWithInstruction(I: InBB->getTerminator()));
1801 if (NewVal && NewVal != PN && !match(V: NewVal, P: m_ConstantExpr()))
1802 return NewVal;
1803
1804 // Check if incoming PHI value can be replaced with constant
1805 // based on implied condition.
1806 BranchInst *TerminatorBI = dyn_cast<BranchInst>(Val: InBB->getTerminator());
1807 const ICmpInst *ICmp = dyn_cast<ICmpInst>(Val: &I);
1808 if (TerminatorBI && TerminatorBI->isConditional() &&
1809 TerminatorBI->getSuccessor(i: 0) != TerminatorBI->getSuccessor(i: 1) && ICmp) {
1810 bool LHSIsTrue = TerminatorBI->getSuccessor(i: 0) == PN->getParent();
1811 std::optional<bool> ImpliedCond = isImpliedCondition(
1812 LHS: TerminatorBI->getCondition(), RHSPred: ICmp->getCmpPredicate(), RHSOp0: Ops[0], RHSOp1: Ops[1],
1813 DL, LHSIsTrue);
1814 if (ImpliedCond)
1815 return ConstantInt::getBool(Ty: I.getType(), V: ImpliedCond.value());
1816 }
1817
1818 return nullptr;
1819}
1820
1821Instruction *InstCombinerImpl::foldOpIntoPhi(Instruction &I, PHINode *PN,
1822 bool AllowMultipleUses) {
1823 unsigned NumPHIValues = PN->getNumIncomingValues();
1824 if (NumPHIValues == 0)
1825 return nullptr;
1826
1827 // We normally only transform phis with a single use. However, if a PHI has
1828 // multiple uses and they are all the same operation, we can fold *all* of the
1829 // uses into the PHI.
1830 bool OneUse = PN->hasOneUse();
1831 bool IdenticalUsers = false;
1832 if (!AllowMultipleUses && !OneUse) {
1833 // Walk the use list for the instruction, comparing them to I.
1834 for (User *U : PN->users()) {
1835 Instruction *UI = cast<Instruction>(Val: U);
1836 if (UI != &I && !I.isIdenticalTo(I: UI))
1837 return nullptr;
1838 }
1839 // Otherwise, we can replace *all* users with the new PHI we form.
1840 IdenticalUsers = true;
1841 }
1842
1843 // Check that all operands are phi-translatable.
1844 for (Value *Op : I.operands()) {
1845 if (Op == PN)
1846 continue;
1847
1848 // Non-instructions never require phi-translation.
1849 auto *I = dyn_cast<Instruction>(Val: Op);
1850 if (!I)
1851 continue;
1852
1853 // Phi-translate can handle phi nodes in the same block.
1854 if (isa<PHINode>(Val: I))
1855 if (I->getParent() == PN->getParent())
1856 continue;
1857
1858 // Operand dominates the block, no phi-translation necessary.
1859 if (DT.dominates(Def: I, BB: PN->getParent()))
1860 continue;
1861
1862 // Not phi-translatable, bail out.
1863 return nullptr;
1864 }
1865
1866 // Check to see whether the instruction can be folded into each phi operand.
1867 // If there is one operand that does not fold, remember the BB it is in.
1868 SmallVector<Value *> NewPhiValues;
1869 SmallVector<unsigned int> OpsToMoveUseToIncomingBB;
1870 bool SeenNonSimplifiedInVal = false;
1871 for (unsigned i = 0; i != NumPHIValues; ++i) {
1872 Value *InVal = PN->getIncomingValue(i);
1873 BasicBlock *InBB = PN->getIncomingBlock(i);
1874
1875 if (auto *NewVal = simplifyInstructionWithPHI(I, PN, InValue: InVal, InBB, DL, SQ)) {
1876 NewPhiValues.push_back(Elt: NewVal);
1877 continue;
1878 }
1879
1880 // Handle some cases that can't be fully simplified, but where we know that
1881 // the two instructions will fold into one.
1882 auto WillFold = [&]() {
1883 if (!InVal->hasUseList() || !InVal->hasOneUser())
1884 return false;
1885
1886 // icmp of ucmp/scmp with constant will fold to icmp.
1887 const APInt *Ignored;
1888 if (isa<CmpIntrinsic>(Val: InVal) &&
1889 match(V: &I, P: m_ICmp(L: m_Specific(V: PN), R: m_APInt(Res&: Ignored))))
1890 return true;
1891
1892 // icmp eq zext(bool), 0 will fold to !bool.
1893 if (isa<ZExtInst>(Val: InVal) &&
1894 cast<ZExtInst>(Val: InVal)->getSrcTy()->isIntOrIntVectorTy(BitWidth: 1) &&
1895 match(V: &I,
1896 P: m_SpecificICmp(MatchPred: ICmpInst::ICMP_EQ, L: m_Specific(V: PN), R: m_Zero())))
1897 return true;
1898
1899 return false;
1900 };
1901
1902 if (WillFold()) {
1903 OpsToMoveUseToIncomingBB.push_back(Elt: i);
1904 NewPhiValues.push_back(Elt: nullptr);
1905 continue;
1906 }
1907
1908 if (!OneUse && !IdenticalUsers)
1909 return nullptr;
1910
1911 if (SeenNonSimplifiedInVal)
1912 return nullptr; // More than one non-simplified value.
1913 SeenNonSimplifiedInVal = true;
1914
1915 // If there is exactly one non-simplified value, we can insert a copy of the
1916 // operation in that block. However, if this is a critical edge, we would
1917 // be inserting the computation on some other paths (e.g. inside a loop).
1918 // Only do this if the pred block is unconditionally branching into the phi
1919 // block. Also, make sure that the pred block is not dead code.
1920 BranchInst *BI = dyn_cast<BranchInst>(Val: InBB->getTerminator());
1921 if (!BI || !BI->isUnconditional() || !DT.isReachableFromEntry(A: InBB))
1922 return nullptr;
1923
1924 NewPhiValues.push_back(Elt: nullptr);
1925 OpsToMoveUseToIncomingBB.push_back(Elt: i);
1926
1927 // If the InVal is an invoke at the end of the pred block, then we can't
1928 // insert a computation after it without breaking the edge.
1929 if (isa<InvokeInst>(Val: InVal))
1930 if (cast<Instruction>(Val: InVal)->getParent() == InBB)
1931 return nullptr;
1932
1933 // Do not push the operation across a loop backedge. This could result in
1934 // an infinite combine loop, and is generally non-profitable (especially
1935 // if the operation was originally outside the loop).
1936 if (isBackEdge(From: InBB, To: PN->getParent()))
1937 return nullptr;
1938 }
1939
1940 // Clone the instruction that uses the phi node and move it into the incoming
1941 // BB because we know that the next iteration of InstCombine will simplify it.
1942 SmallDenseMap<BasicBlock *, Instruction *> Clones;
1943 for (auto OpIndex : OpsToMoveUseToIncomingBB) {
1944 Value *Op = PN->getIncomingValue(i: OpIndex);
1945 BasicBlock *OpBB = PN->getIncomingBlock(i: OpIndex);
1946
1947 Instruction *Clone = Clones.lookup(Val: OpBB);
1948 if (!Clone) {
1949 Clone = I.clone();
1950 for (Use &U : Clone->operands()) {
1951 if (U == PN)
1952 U = Op;
1953 else
1954 U = U->DoPHITranslation(CurBB: PN->getParent(), PredBB: OpBB);
1955 }
1956 Clone = InsertNewInstBefore(New: Clone, Old: OpBB->getTerminator()->getIterator());
1957 Clones.insert(KV: {OpBB, Clone});
1958 }
1959
1960 NewPhiValues[OpIndex] = Clone;
1961 }
1962
1963 // Okay, we can do the transformation: create the new PHI node.
1964 PHINode *NewPN = PHINode::Create(Ty: I.getType(), NumReservedValues: PN->getNumIncomingValues());
1965 InsertNewInstBefore(New: NewPN, Old: PN->getIterator());
1966 NewPN->takeName(V: PN);
1967 NewPN->setDebugLoc(PN->getDebugLoc());
1968
1969 for (unsigned i = 0; i != NumPHIValues; ++i)
1970 NewPN->addIncoming(V: NewPhiValues[i], BB: PN->getIncomingBlock(i));
1971
1972 if (IdenticalUsers) {
1973 for (User *U : make_early_inc_range(Range: PN->users())) {
1974 Instruction *User = cast<Instruction>(Val: U);
1975 if (User == &I)
1976 continue;
1977 replaceInstUsesWith(I&: *User, V: NewPN);
1978 eraseInstFromFunction(I&: *User);
1979 }
1980 OneUse = true;
1981 }
1982
1983 if (OneUse) {
1984 replaceAllDbgUsesWith(From&: const_cast<PHINode &>(*PN),
1985 To&: const_cast<PHINode &>(*NewPN),
1986 DomPoint&: const_cast<PHINode &>(*PN), DT);
1987 }
1988 return replaceInstUsesWith(I, V: NewPN);
1989}
1990
1991Instruction *InstCombinerImpl::foldBinopWithRecurrence(BinaryOperator &BO) {
1992 if (!BO.isAssociative())
1993 return nullptr;
1994
1995 // Find the interleaved binary ops.
1996 auto Opc = BO.getOpcode();
1997 auto *BO0 = dyn_cast<BinaryOperator>(Val: BO.getOperand(i_nocapture: 0));
1998 auto *BO1 = dyn_cast<BinaryOperator>(Val: BO.getOperand(i_nocapture: 1));
1999 if (!BO0 || !BO1 || !BO0->hasNUses(N: 2) || !BO1->hasNUses(N: 2) ||
2000 BO0->getOpcode() != Opc || BO1->getOpcode() != Opc ||
2001 !BO0->isAssociative() || !BO1->isAssociative() ||
2002 BO0->getParent() != BO1->getParent())
2003 return nullptr;
2004
2005 assert(BO.isCommutative() && BO0->isCommutative() && BO1->isCommutative() &&
2006 "Expected commutative instructions!");
2007
2008 // Find the matching phis, forming the recurrences.
2009 PHINode *PN0, *PN1;
2010 Value *Start0, *Step0, *Start1, *Step1;
2011 if (!matchSimpleRecurrence(I: BO0, P&: PN0, Start&: Start0, Step&: Step0) || !PN0->hasOneUse() ||
2012 !matchSimpleRecurrence(I: BO1, P&: PN1, Start&: Start1, Step&: Step1) || !PN1->hasOneUse() ||
2013 PN0->getParent() != PN1->getParent())
2014 return nullptr;
2015
2016 assert(PN0->getNumIncomingValues() == 2 && PN1->getNumIncomingValues() == 2 &&
2017 "Expected PHIs with two incoming values!");
2018
2019 // Convert the start and step values to constants.
2020 auto *Init0 = dyn_cast<Constant>(Val: Start0);
2021 auto *Init1 = dyn_cast<Constant>(Val: Start1);
2022 auto *C0 = dyn_cast<Constant>(Val: Step0);
2023 auto *C1 = dyn_cast<Constant>(Val: Step1);
2024 if (!Init0 || !Init1 || !C0 || !C1)
2025 return nullptr;
2026
2027 // Fold the recurrence constants.
2028 auto *Init = ConstantFoldBinaryInstruction(Opcode: Opc, V1: Init0, V2: Init1);
2029 auto *C = ConstantFoldBinaryInstruction(Opcode: Opc, V1: C0, V2: C1);
2030 if (!Init || !C)
2031 return nullptr;
2032
2033 // Create the reduced PHI.
2034 auto *NewPN = PHINode::Create(Ty: PN0->getType(), NumReservedValues: PN0->getNumIncomingValues(),
2035 NameStr: "reduced.phi");
2036
2037 // Create the new binary op.
2038 auto *NewBO = BinaryOperator::Create(Op: Opc, S1: NewPN, S2: C);
2039 if (Opc == Instruction::FAdd || Opc == Instruction::FMul) {
2040 // Intersect FMF flags for FADD and FMUL.
2041 FastMathFlags Intersect = BO0->getFastMathFlags() &
2042 BO1->getFastMathFlags() & BO.getFastMathFlags();
2043 NewBO->setFastMathFlags(Intersect);
2044 } else {
2045 OverflowTracking Flags;
2046 Flags.AllKnownNonNegative = false;
2047 Flags.AllKnownNonZero = false;
2048 Flags.mergeFlags(I&: *BO0);
2049 Flags.mergeFlags(I&: *BO1);
2050 Flags.mergeFlags(I&: BO);
2051 Flags.applyFlags(I&: *NewBO);
2052 }
2053 NewBO->takeName(V: &BO);
2054
2055 for (unsigned I = 0, E = PN0->getNumIncomingValues(); I != E; ++I) {
2056 auto *V = PN0->getIncomingValue(i: I);
2057 auto *BB = PN0->getIncomingBlock(i: I);
2058 if (V == Init0) {
2059 assert(((PN1->getIncomingValue(0) == Init1 &&
2060 PN1->getIncomingBlock(0) == BB) ||
2061 (PN1->getIncomingValue(1) == Init1 &&
2062 PN1->getIncomingBlock(1) == BB)) &&
2063 "Invalid incoming block!");
2064 NewPN->addIncoming(V: Init, BB);
2065 } else if (V == BO0) {
2066 assert(((PN1->getIncomingValue(0) == BO1 &&
2067 PN1->getIncomingBlock(0) == BB) ||
2068 (PN1->getIncomingValue(1) == BO1 &&
2069 PN1->getIncomingBlock(1) == BB)) &&
2070 "Invalid incoming block!");
2071 NewPN->addIncoming(V: NewBO, BB);
2072 } else
2073 llvm_unreachable("Unexpected incoming value!");
2074 }
2075
2076 LLVM_DEBUG(dbgs() << " Combined " << *PN0 << "\n " << *BO0
2077 << "\n with " << *PN1 << "\n " << *BO1
2078 << '\n');
2079
2080 // Insert the new recurrence and remove the old (dead) ones.
2081 InsertNewInstWith(New: NewPN, Old: PN0->getIterator());
2082 InsertNewInstWith(New: NewBO, Old: BO0->getIterator());
2083
2084 eraseInstFromFunction(
2085 I&: *replaceInstUsesWith(I&: *BO0, V: PoisonValue::get(T: BO0->getType())));
2086 eraseInstFromFunction(
2087 I&: *replaceInstUsesWith(I&: *BO1, V: PoisonValue::get(T: BO1->getType())));
2088 eraseInstFromFunction(I&: *PN0);
2089 eraseInstFromFunction(I&: *PN1);
2090
2091 return replaceInstUsesWith(I&: BO, V: NewBO);
2092}
2093
2094Instruction *InstCombinerImpl::foldBinopWithPhiOperands(BinaryOperator &BO) {
2095 // Attempt to fold binary operators whose operands are simple recurrences.
2096 if (auto *NewBO = foldBinopWithRecurrence(BO))
2097 return NewBO;
2098
2099 // TODO: This should be similar to the incoming values check in foldOpIntoPhi:
2100 // we are guarding against replicating the binop in >1 predecessor.
2101 // This could miss matching a phi with 2 constant incoming values.
2102 auto *Phi0 = dyn_cast<PHINode>(Val: BO.getOperand(i_nocapture: 0));
2103 auto *Phi1 = dyn_cast<PHINode>(Val: BO.getOperand(i_nocapture: 1));
2104 if (!Phi0 || !Phi1 || !Phi0->hasOneUse() || !Phi1->hasOneUse() ||
2105 Phi0->getNumOperands() != Phi1->getNumOperands())
2106 return nullptr;
2107
2108 // TODO: Remove the restriction for binop being in the same block as the phis.
2109 if (BO.getParent() != Phi0->getParent() ||
2110 BO.getParent() != Phi1->getParent())
2111 return nullptr;
2112
2113 // Fold if there is at least one specific constant value in phi0 or phi1's
2114 // incoming values that comes from the same block and this specific constant
2115 // value can be used to do optimization for specific binary operator.
2116 // For example:
2117 // %phi0 = phi i32 [0, %bb0], [%i, %bb1]
2118 // %phi1 = phi i32 [%j, %bb0], [0, %bb1]
2119 // %add = add i32 %phi0, %phi1
2120 // ==>
2121 // %add = phi i32 [%j, %bb0], [%i, %bb1]
2122 Constant *C = ConstantExpr::getBinOpIdentity(Opcode: BO.getOpcode(), Ty: BO.getType(),
2123 /*AllowRHSConstant*/ false);
2124 if (C) {
2125 SmallVector<Value *, 4> NewIncomingValues;
2126 auto CanFoldIncomingValuePair = [&](std::tuple<Use &, Use &> T) {
2127 auto &Phi0Use = std::get<0>(t&: T);
2128 auto &Phi1Use = std::get<1>(t&: T);
2129 if (Phi0->getIncomingBlock(U: Phi0Use) != Phi1->getIncomingBlock(U: Phi1Use))
2130 return false;
2131 Value *Phi0UseV = Phi0Use.get();
2132 Value *Phi1UseV = Phi1Use.get();
2133 if (Phi0UseV == C)
2134 NewIncomingValues.push_back(Elt: Phi1UseV);
2135 else if (Phi1UseV == C)
2136 NewIncomingValues.push_back(Elt: Phi0UseV);
2137 else
2138 return false;
2139 return true;
2140 };
2141
2142 if (all_of(Range: zip(t: Phi0->operands(), u: Phi1->operands()),
2143 P: CanFoldIncomingValuePair)) {
2144 PHINode *NewPhi =
2145 PHINode::Create(Ty: Phi0->getType(), NumReservedValues: Phi0->getNumOperands());
2146 assert(NewIncomingValues.size() == Phi0->getNumOperands() &&
2147 "The number of collected incoming values should equal the number "
2148 "of the original PHINode operands!");
2149 for (unsigned I = 0; I < Phi0->getNumOperands(); I++)
2150 NewPhi->addIncoming(V: NewIncomingValues[I], BB: Phi0->getIncomingBlock(i: I));
2151 return NewPhi;
2152 }
2153 }
2154
2155 if (Phi0->getNumOperands() != 2 || Phi1->getNumOperands() != 2)
2156 return nullptr;
2157
2158 // Match a pair of incoming constants for one of the predecessor blocks.
2159 BasicBlock *ConstBB, *OtherBB;
2160 Constant *C0, *C1;
2161 if (match(V: Phi0->getIncomingValue(i: 0), P: m_ImmConstant(C&: C0))) {
2162 ConstBB = Phi0->getIncomingBlock(i: 0);
2163 OtherBB = Phi0->getIncomingBlock(i: 1);
2164 } else if (match(V: Phi0->getIncomingValue(i: 1), P: m_ImmConstant(C&: C0))) {
2165 ConstBB = Phi0->getIncomingBlock(i: 1);
2166 OtherBB = Phi0->getIncomingBlock(i: 0);
2167 } else {
2168 return nullptr;
2169 }
2170 if (!match(V: Phi1->getIncomingValueForBlock(BB: ConstBB), P: m_ImmConstant(C&: C1)))
2171 return nullptr;
2172
2173 // The block that we are hoisting to must reach here unconditionally.
2174 // Otherwise, we could be speculatively executing an expensive or
2175 // non-speculative op.
2176 auto *PredBlockBranch = dyn_cast<BranchInst>(Val: OtherBB->getTerminator());
2177 if (!PredBlockBranch || PredBlockBranch->isConditional() ||
2178 !DT.isReachableFromEntry(A: OtherBB))
2179 return nullptr;
2180
2181 // TODO: This check could be tightened to only apply to binops (div/rem) that
2182 // are not safe to speculatively execute. But that could allow hoisting
2183 // potentially expensive instructions (fdiv for example).
2184 for (auto BBIter = BO.getParent()->begin(); &*BBIter != &BO; ++BBIter)
2185 if (!isGuaranteedToTransferExecutionToSuccessor(I: &*BBIter))
2186 return nullptr;
2187
2188 // Fold constants for the predecessor block with constant incoming values.
2189 Constant *NewC = ConstantFoldBinaryOpOperands(Opcode: BO.getOpcode(), LHS: C0, RHS: C1, DL);
2190 if (!NewC)
2191 return nullptr;
2192
2193 // Make a new binop in the predecessor block with the non-constant incoming
2194 // values.
2195 Builder.SetInsertPoint(PredBlockBranch);
2196 Value *NewBO = Builder.CreateBinOp(Opc: BO.getOpcode(),
2197 LHS: Phi0->getIncomingValueForBlock(BB: OtherBB),
2198 RHS: Phi1->getIncomingValueForBlock(BB: OtherBB));
2199 if (auto *NotFoldedNewBO = dyn_cast<BinaryOperator>(Val: NewBO))
2200 NotFoldedNewBO->copyIRFlags(V: &BO);
2201
2202 // Replace the binop with a phi of the new values. The old phis are dead.
2203 PHINode *NewPhi = PHINode::Create(Ty: BO.getType(), NumReservedValues: 2);
2204 NewPhi->addIncoming(V: NewBO, BB: OtherBB);
2205 NewPhi->addIncoming(V: NewC, BB: ConstBB);
2206 return NewPhi;
2207}
2208
2209Instruction *InstCombinerImpl::foldBinOpIntoSelectOrPhi(BinaryOperator &I) {
2210 if (!isa<Constant>(Val: I.getOperand(i_nocapture: 1)))
2211 return nullptr;
2212
2213 if (auto *Sel = dyn_cast<SelectInst>(Val: I.getOperand(i_nocapture: 0))) {
2214 if (Instruction *NewSel = FoldOpIntoSelect(Op&: I, SI: Sel))
2215 return NewSel;
2216 } else if (auto *PN = dyn_cast<PHINode>(Val: I.getOperand(i_nocapture: 0))) {
2217 if (Instruction *NewPhi = foldOpIntoPhi(I, PN))
2218 return NewPhi;
2219 }
2220 return nullptr;
2221}
2222
2223static bool shouldMergeGEPs(GEPOperator &GEP, GEPOperator &Src) {
2224 // If this GEP has only 0 indices, it is the same pointer as
2225 // Src. If Src is not a trivial GEP too, don't combine
2226 // the indices.
2227 if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() &&
2228 !Src.hasOneUse())
2229 return false;
2230 return true;
2231}
2232
2233/// Find a constant NewC that has property:
2234/// shuffle(NewC, ShMask) = C
2235/// Returns nullptr if such a constant does not exist e.g. ShMask=<0,0> C=<1,2>
2236///
2237/// A 1-to-1 mapping is not required. Example:
2238/// ShMask = <1,1,2,2> and C = <5,5,6,6> --> NewC = <poison,5,6,poison>
2239Constant *InstCombinerImpl::unshuffleConstant(ArrayRef<int> ShMask, Constant *C,
2240 VectorType *NewCTy) {
2241 if (isa<ScalableVectorType>(Val: NewCTy)) {
2242 Constant *Splat = C->getSplatValue();
2243 if (!Splat)
2244 return nullptr;
2245 return ConstantVector::getSplat(EC: NewCTy->getElementCount(), Elt: Splat);
2246 }
2247
2248 if (cast<FixedVectorType>(Val: NewCTy)->getNumElements() >
2249 cast<FixedVectorType>(Val: C->getType())->getNumElements())
2250 return nullptr;
2251
2252 unsigned NewCNumElts = cast<FixedVectorType>(Val: NewCTy)->getNumElements();
2253 PoisonValue *PoisonScalar = PoisonValue::get(T: C->getType()->getScalarType());
2254 SmallVector<Constant *, 16> NewVecC(NewCNumElts, PoisonScalar);
2255 unsigned NumElts = cast<FixedVectorType>(Val: C->getType())->getNumElements();
2256 for (unsigned I = 0; I < NumElts; ++I) {
2257 Constant *CElt = C->getAggregateElement(Elt: I);
2258 if (ShMask[I] >= 0) {
2259 assert(ShMask[I] < (int)NumElts && "Not expecting narrowing shuffle");
2260 Constant *NewCElt = NewVecC[ShMask[I]];
2261 // Bail out if:
2262 // 1. The constant vector contains a constant expression.
2263 // 2. The shuffle needs an element of the constant vector that can't
2264 // be mapped to a new constant vector.
2265 // 3. This is a widening shuffle that copies elements of V1 into the
2266 // extended elements (extending with poison is allowed).
2267 if (!CElt || (!isa<PoisonValue>(Val: NewCElt) && NewCElt != CElt) ||
2268 I >= NewCNumElts)
2269 return nullptr;
2270 NewVecC[ShMask[I]] = CElt;
2271 }
2272 }
2273 return ConstantVector::get(V: NewVecC);
2274}
2275
2276Instruction *InstCombinerImpl::foldVectorBinop(BinaryOperator &Inst) {
2277 if (!isa<VectorType>(Val: Inst.getType()))
2278 return nullptr;
2279
2280 BinaryOperator::BinaryOps Opcode = Inst.getOpcode();
2281 Value *LHS = Inst.getOperand(i_nocapture: 0), *RHS = Inst.getOperand(i_nocapture: 1);
2282 assert(cast<VectorType>(LHS->getType())->getElementCount() ==
2283 cast<VectorType>(Inst.getType())->getElementCount());
2284 assert(cast<VectorType>(RHS->getType())->getElementCount() ==
2285 cast<VectorType>(Inst.getType())->getElementCount());
2286
2287 // If both operands of the binop are vector concatenations, then perform the
2288 // narrow binop on each pair of the source operands followed by concatenation
2289 // of the results.
2290 Value *L0, *L1, *R0, *R1;
2291 ArrayRef<int> Mask;
2292 if (match(V: LHS, P: m_Shuffle(v1: m_Value(V&: L0), v2: m_Value(V&: L1), mask: m_Mask(Mask))) &&
2293 match(V: RHS, P: m_Shuffle(v1: m_Value(V&: R0), v2: m_Value(V&: R1), mask: m_SpecificMask(Mask))) &&
2294 LHS->hasOneUse() && RHS->hasOneUse() &&
2295 cast<ShuffleVectorInst>(Val: LHS)->isConcat() &&
2296 cast<ShuffleVectorInst>(Val: RHS)->isConcat()) {
2297 // This transform does not have the speculative execution constraint as
2298 // below because the shuffle is a concatenation. The new binops are
2299 // operating on exactly the same elements as the existing binop.
2300 // TODO: We could ease the mask requirement to allow different undef lanes,
2301 // but that requires an analysis of the binop-with-undef output value.
2302 Value *NewBO0 = Builder.CreateBinOp(Opc: Opcode, LHS: L0, RHS: R0);
2303 if (auto *BO = dyn_cast<BinaryOperator>(Val: NewBO0))
2304 BO->copyIRFlags(V: &Inst);
2305 Value *NewBO1 = Builder.CreateBinOp(Opc: Opcode, LHS: L1, RHS: R1);
2306 if (auto *BO = dyn_cast<BinaryOperator>(Val: NewBO1))
2307 BO->copyIRFlags(V: &Inst);
2308 return new ShuffleVectorInst(NewBO0, NewBO1, Mask);
2309 }
2310
2311 auto createBinOpReverse = [&](Value *X, Value *Y) {
2312 Value *V = Builder.CreateBinOp(Opc: Opcode, LHS: X, RHS: Y, Name: Inst.getName());
2313 if (auto *BO = dyn_cast<BinaryOperator>(Val: V))
2314 BO->copyIRFlags(V: &Inst);
2315 Module *M = Inst.getModule();
2316 Function *F = Intrinsic::getOrInsertDeclaration(
2317 M, id: Intrinsic::vector_reverse, Tys: V->getType());
2318 return CallInst::Create(Func: F, Args: V);
2319 };
2320
2321 // NOTE: Reverse shuffles don't require the speculative execution protection
2322 // below because they don't affect which lanes take part in the computation.
2323
2324 Value *V1, *V2;
2325 if (match(V: LHS, P: m_VecReverse(Op0: m_Value(V&: V1)))) {
2326 // Op(rev(V1), rev(V2)) -> rev(Op(V1, V2))
2327 if (match(V: RHS, P: m_VecReverse(Op0: m_Value(V&: V2))) &&
2328 (LHS->hasOneUse() || RHS->hasOneUse() ||
2329 (LHS == RHS && LHS->hasNUses(N: 2))))
2330 return createBinOpReverse(V1, V2);
2331
2332 // Op(rev(V1), RHSSplat)) -> rev(Op(V1, RHSSplat))
2333 if (LHS->hasOneUse() && isSplatValue(V: RHS))
2334 return createBinOpReverse(V1, RHS);
2335 }
2336 // Op(LHSSplat, rev(V2)) -> rev(Op(LHSSplat, V2))
2337 else if (isSplatValue(V: LHS) && match(V: RHS, P: m_OneUse(SubPattern: m_VecReverse(Op0: m_Value(V&: V2)))))
2338 return createBinOpReverse(LHS, V2);
2339
2340 auto createBinOpVPReverse = [&](Value *X, Value *Y, Value *EVL) {
2341 Value *V = Builder.CreateBinOp(Opc: Opcode, LHS: X, RHS: Y, Name: Inst.getName());
2342 if (auto *BO = dyn_cast<BinaryOperator>(Val: V))
2343 BO->copyIRFlags(V: &Inst);
2344
2345 ElementCount EC = cast<VectorType>(Val: V->getType())->getElementCount();
2346 Value *AllTrueMask = Builder.CreateVectorSplat(EC, V: Builder.getTrue());
2347 Module *M = Inst.getModule();
2348 Function *F = Intrinsic::getOrInsertDeclaration(
2349 M, id: Intrinsic::experimental_vp_reverse, Tys: V->getType());
2350 return CallInst::Create(Func: F, Args: {V, AllTrueMask, EVL});
2351 };
2352
2353 Value *EVL;
2354 if (match(V: LHS, P: m_Intrinsic<Intrinsic::experimental_vp_reverse>(
2355 Op0: m_Value(V&: V1), Op1: m_AllOnes(), Op2: m_Value(V&: EVL)))) {
2356 // Op(rev(V1), rev(V2)) -> rev(Op(V1, V2))
2357 if (match(V: RHS, P: m_Intrinsic<Intrinsic::experimental_vp_reverse>(
2358 Op0: m_Value(V&: V2), Op1: m_AllOnes(), Op2: m_Specific(V: EVL))) &&
2359 (LHS->hasOneUse() || RHS->hasOneUse() ||
2360 (LHS == RHS && LHS->hasNUses(N: 2))))
2361 return createBinOpVPReverse(V1, V2, EVL);
2362
2363 // Op(rev(V1), RHSSplat)) -> rev(Op(V1, RHSSplat))
2364 if (LHS->hasOneUse() && isSplatValue(V: RHS))
2365 return createBinOpVPReverse(V1, RHS, EVL);
2366 }
2367 // Op(LHSSplat, rev(V2)) -> rev(Op(LHSSplat, V2))
2368 else if (isSplatValue(V: LHS) &&
2369 match(V: RHS, P: m_Intrinsic<Intrinsic::experimental_vp_reverse>(
2370 Op0: m_Value(V&: V2), Op1: m_AllOnes(), Op2: m_Value(V&: EVL))))
2371 return createBinOpVPReverse(LHS, V2, EVL);
2372
2373 // It may not be safe to reorder shuffles and things like div, urem, etc.
2374 // because we may trap when executing those ops on unknown vector elements.
2375 // See PR20059.
2376 if (!isSafeToSpeculativelyExecuteWithVariableReplaced(I: &Inst))
2377 return nullptr;
2378
2379 auto createBinOpShuffle = [&](Value *X, Value *Y, ArrayRef<int> M) {
2380 Value *XY = Builder.CreateBinOp(Opc: Opcode, LHS: X, RHS: Y);
2381 if (auto *BO = dyn_cast<BinaryOperator>(Val: XY))
2382 BO->copyIRFlags(V: &Inst);
2383 return new ShuffleVectorInst(XY, M);
2384 };
2385
2386 // If both arguments of the binary operation are shuffles that use the same
2387 // mask and shuffle within a single vector, move the shuffle after the binop.
2388 if (match(V: LHS, P: m_Shuffle(v1: m_Value(V&: V1), v2: m_Poison(), mask: m_Mask(Mask))) &&
2389 match(V: RHS, P: m_Shuffle(v1: m_Value(V&: V2), v2: m_Poison(), mask: m_SpecificMask(Mask))) &&
2390 V1->getType() == V2->getType() &&
2391 (LHS->hasOneUse() || RHS->hasOneUse() || LHS == RHS)) {
2392 // Op(shuffle(V1, Mask), shuffle(V2, Mask)) -> shuffle(Op(V1, V2), Mask)
2393 return createBinOpShuffle(V1, V2, Mask);
2394 }
2395
2396 // If both arguments of a commutative binop are select-shuffles that use the
2397 // same mask with commuted operands, the shuffles are unnecessary.
2398 if (Inst.isCommutative() &&
2399 match(V: LHS, P: m_Shuffle(v1: m_Value(V&: V1), v2: m_Value(V&: V2), mask: m_Mask(Mask))) &&
2400 match(V: RHS,
2401 P: m_Shuffle(v1: m_Specific(V: V2), v2: m_Specific(V: V1), mask: m_SpecificMask(Mask)))) {
2402 auto *LShuf = cast<ShuffleVectorInst>(Val: LHS);
2403 auto *RShuf = cast<ShuffleVectorInst>(Val: RHS);
2404 // TODO: Allow shuffles that contain undefs in the mask?
2405 // That is legal, but it reduces undef knowledge.
2406 // TODO: Allow arbitrary shuffles by shuffling after binop?
2407 // That might be legal, but we have to deal with poison.
2408 if (LShuf->isSelect() &&
2409 !is_contained(Range: LShuf->getShuffleMask(), Element: PoisonMaskElem) &&
2410 RShuf->isSelect() &&
2411 !is_contained(Range: RShuf->getShuffleMask(), Element: PoisonMaskElem)) {
2412 // Example:
2413 // LHS = shuffle V1, V2, <0, 5, 6, 3>
2414 // RHS = shuffle V2, V1, <0, 5, 6, 3>
2415 // LHS + RHS --> (V10+V20, V21+V11, V22+V12, V13+V23) --> V1 + V2
2416 Instruction *NewBO = BinaryOperator::Create(Op: Opcode, S1: V1, S2: V2);
2417 NewBO->copyIRFlags(V: &Inst);
2418 return NewBO;
2419 }
2420 }
2421
2422 // If one argument is a shuffle within one vector and the other is a constant,
2423 // try moving the shuffle after the binary operation. This canonicalization
2424 // intends to move shuffles closer to other shuffles and binops closer to
2425 // other binops, so they can be folded. It may also enable demanded elements
2426 // transforms.
2427 Constant *C;
2428 if (match(V: &Inst, P: m_c_BinOp(L: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: V1), v2: m_Poison(),
2429 mask: m_Mask(Mask))),
2430 R: m_ImmConstant(C)))) {
2431 assert(Inst.getType()->getScalarType() == V1->getType()->getScalarType() &&
2432 "Shuffle should not change scalar type");
2433
2434 bool ConstOp1 = isa<Constant>(Val: RHS);
2435 if (Constant *NewC =
2436 unshuffleConstant(ShMask: Mask, C, NewCTy: cast<VectorType>(Val: V1->getType()))) {
2437 // For fixed vectors, lanes of NewC not used by the shuffle will be poison
2438 // which will cause UB for div/rem. Mask them with a safe constant.
2439 if (isa<FixedVectorType>(Val: V1->getType()) && Inst.isIntDivRem())
2440 NewC = getSafeVectorConstantForBinop(Opcode, In: NewC, IsRHSConstant: ConstOp1);
2441
2442 // Op(shuffle(V1, Mask), C) -> shuffle(Op(V1, NewC), Mask)
2443 // Op(C, shuffle(V1, Mask)) -> shuffle(Op(NewC, V1), Mask)
2444 Value *NewLHS = ConstOp1 ? V1 : NewC;
2445 Value *NewRHS = ConstOp1 ? NewC : V1;
2446 return createBinOpShuffle(NewLHS, NewRHS, Mask);
2447 }
2448 }
2449
2450 // Try to reassociate to sink a splat shuffle after a binary operation.
2451 if (Inst.isAssociative() && Inst.isCommutative()) {
2452 // Canonicalize shuffle operand as LHS.
2453 if (isa<ShuffleVectorInst>(Val: RHS))
2454 std::swap(a&: LHS, b&: RHS);
2455
2456 Value *X;
2457 ArrayRef<int> MaskC;
2458 int SplatIndex;
2459 Value *Y, *OtherOp;
2460 if (!match(V: LHS,
2461 P: m_OneUse(SubPattern: m_Shuffle(v1: m_Value(V&: X), v2: m_Undef(), mask: m_Mask(MaskC)))) ||
2462 !match(Mask: MaskC, P: m_SplatOrPoisonMask(SplatIndex)) ||
2463 X->getType() != Inst.getType() ||
2464 !match(V: RHS, P: m_OneUse(SubPattern: m_BinOp(Opcode, L: m_Value(V&: Y), R: m_Value(V&: OtherOp)))))
2465 return nullptr;
2466
2467 // FIXME: This may not be safe if the analysis allows undef elements. By
2468 // moving 'Y' before the splat shuffle, we are implicitly assuming
2469 // that it is not undef/poison at the splat index.
2470 if (isSplatValue(V: OtherOp, Index: SplatIndex)) {
2471 std::swap(a&: Y, b&: OtherOp);
2472 } else if (!isSplatValue(V: Y, Index: SplatIndex)) {
2473 return nullptr;
2474 }
2475
2476 // X and Y are splatted values, so perform the binary operation on those
2477 // values followed by a splat followed by the 2nd binary operation:
2478 // bo (splat X), (bo Y, OtherOp) --> bo (splat (bo X, Y)), OtherOp
2479 Value *NewBO = Builder.CreateBinOp(Opc: Opcode, LHS: X, RHS: Y);
2480 SmallVector<int, 8> NewMask(MaskC.size(), SplatIndex);
2481 Value *NewSplat = Builder.CreateShuffleVector(V: NewBO, Mask: NewMask);
2482 Instruction *R = BinaryOperator::Create(Op: Opcode, S1: NewSplat, S2: OtherOp);
2483
2484 // Intersect FMF on both new binops. Other (poison-generating) flags are
2485 // dropped to be safe.
2486 if (isa<FPMathOperator>(Val: R)) {
2487 R->copyFastMathFlags(I: &Inst);
2488 R->andIRFlags(V: RHS);
2489 }
2490 if (auto *NewInstBO = dyn_cast<BinaryOperator>(Val: NewBO))
2491 NewInstBO->copyIRFlags(V: R);
2492 return R;
2493 }
2494
2495 return nullptr;
2496}
2497
2498/// Try to narrow the width of a binop if at least 1 operand is an extend of
2499/// of a value. This requires a potentially expensive known bits check to make
2500/// sure the narrow op does not overflow.
2501Instruction *InstCombinerImpl::narrowMathIfNoOverflow(BinaryOperator &BO) {
2502 // We need at least one extended operand.
2503 Value *Op0 = BO.getOperand(i_nocapture: 0), *Op1 = BO.getOperand(i_nocapture: 1);
2504
2505 // If this is a sub, we swap the operands since we always want an extension
2506 // on the RHS. The LHS can be an extension or a constant.
2507 if (BO.getOpcode() == Instruction::Sub)
2508 std::swap(a&: Op0, b&: Op1);
2509
2510 Value *X;
2511 bool IsSext = match(V: Op0, P: m_SExt(Op: m_Value(V&: X)));
2512 if (!IsSext && !match(V: Op0, P: m_ZExt(Op: m_Value(V&: X))))
2513 return nullptr;
2514
2515 // If both operands are the same extension from the same source type and we
2516 // can eliminate at least one (hasOneUse), this might work.
2517 CastInst::CastOps CastOpc = IsSext ? Instruction::SExt : Instruction::ZExt;
2518 Value *Y;
2519 if (!(match(V: Op1, P: m_ZExtOrSExt(Op: m_Value(V&: Y))) && X->getType() == Y->getType() &&
2520 cast<Operator>(Val: Op1)->getOpcode() == CastOpc &&
2521 (Op0->hasOneUse() || Op1->hasOneUse()))) {
2522 // If that did not match, see if we have a suitable constant operand.
2523 // Truncating and extending must produce the same constant.
2524 Constant *WideC;
2525 if (!Op0->hasOneUse() || !match(V: Op1, P: m_Constant(C&: WideC)))
2526 return nullptr;
2527 Constant *NarrowC = getLosslessTrunc(C: WideC, TruncTy: X->getType(), ExtOp: CastOpc);
2528 if (!NarrowC)
2529 return nullptr;
2530 Y = NarrowC;
2531 }
2532
2533 // Swap back now that we found our operands.
2534 if (BO.getOpcode() == Instruction::Sub)
2535 std::swap(a&: X, b&: Y);
2536
2537 // Both operands have narrow versions. Last step: the math must not overflow
2538 // in the narrow width.
2539 if (!willNotOverflow(Opcode: BO.getOpcode(), LHS: X, RHS: Y, CxtI: BO, IsSigned: IsSext))
2540 return nullptr;
2541
2542 // bo (ext X), (ext Y) --> ext (bo X, Y)
2543 // bo (ext X), C --> ext (bo X, C')
2544 Value *NarrowBO = Builder.CreateBinOp(Opc: BO.getOpcode(), LHS: X, RHS: Y, Name: "narrow");
2545 if (auto *NewBinOp = dyn_cast<BinaryOperator>(Val: NarrowBO)) {
2546 if (IsSext)
2547 NewBinOp->setHasNoSignedWrap();
2548 else
2549 NewBinOp->setHasNoUnsignedWrap();
2550 }
2551 return CastInst::Create(CastOpc, S: NarrowBO, Ty: BO.getType());
2552}
2553
2554/// Determine nowrap flags for (gep (gep p, x), y) to (gep p, (x + y))
2555/// transform.
2556static GEPNoWrapFlags getMergedGEPNoWrapFlags(GEPOperator &GEP1,
2557 GEPOperator &GEP2) {
2558 return GEP1.getNoWrapFlags().intersectForOffsetAdd(Other: GEP2.getNoWrapFlags());
2559}
2560
2561/// Thread a GEP operation with constant indices through the constant true/false
2562/// arms of a select.
2563static Instruction *foldSelectGEP(GetElementPtrInst &GEP,
2564 InstCombiner::BuilderTy &Builder) {
2565 if (!GEP.hasAllConstantIndices())
2566 return nullptr;
2567
2568 Instruction *Sel;
2569 Value *Cond;
2570 Constant *TrueC, *FalseC;
2571 if (!match(V: GEP.getPointerOperand(), P: m_Instruction(I&: Sel)) ||
2572 !match(V: Sel,
2573 P: m_Select(C: m_Value(V&: Cond), L: m_Constant(C&: TrueC), R: m_Constant(C&: FalseC))))
2574 return nullptr;
2575
2576 // gep (select Cond, TrueC, FalseC), IndexC --> select Cond, TrueC', FalseC'
2577 // Propagate 'inbounds' and metadata from existing instructions.
2578 // Note: using IRBuilder to create the constants for efficiency.
2579 SmallVector<Value *, 4> IndexC(GEP.indices());
2580 GEPNoWrapFlags NW = GEP.getNoWrapFlags();
2581 Type *Ty = GEP.getSourceElementType();
2582 Value *NewTrueC = Builder.CreateGEP(Ty, Ptr: TrueC, IdxList: IndexC, Name: "", NW);
2583 Value *NewFalseC = Builder.CreateGEP(Ty, Ptr: FalseC, IdxList: IndexC, Name: "", NW);
2584 return SelectInst::Create(C: Cond, S1: NewTrueC, S2: NewFalseC, NameStr: "", InsertBefore: nullptr, MDFrom: Sel);
2585}
2586
2587// Canonicalization:
2588// gep T, (gep i8, base, C1), (Index + C2) into
2589// gep T, (gep i8, base, C1 + C2 * sizeof(T)), Index
2590static Instruction *canonicalizeGEPOfConstGEPI8(GetElementPtrInst &GEP,
2591 GEPOperator *Src,
2592 InstCombinerImpl &IC) {
2593 if (GEP.getNumIndices() != 1)
2594 return nullptr;
2595 auto &DL = IC.getDataLayout();
2596 Value *Base;
2597 const APInt *C1;
2598 if (!match(V: Src, P: m_PtrAdd(PointerOp: m_Value(V&: Base), OffsetOp: m_APInt(Res&: C1))))
2599 return nullptr;
2600 Value *VarIndex;
2601 const APInt *C2;
2602 Type *PtrTy = Src->getType()->getScalarType();
2603 unsigned IndexSizeInBits = DL.getIndexTypeSizeInBits(Ty: PtrTy);
2604 if (!match(V: GEP.getOperand(i_nocapture: 1), P: m_AddLike(L: m_Value(V&: VarIndex), R: m_APInt(Res&: C2))))
2605 return nullptr;
2606 if (C1->getBitWidth() != IndexSizeInBits ||
2607 C2->getBitWidth() != IndexSizeInBits)
2608 return nullptr;
2609 Type *BaseType = GEP.getSourceElementType();
2610 if (isa<ScalableVectorType>(Val: BaseType))
2611 return nullptr;
2612 APInt TypeSize(IndexSizeInBits, DL.getTypeAllocSize(Ty: BaseType));
2613 APInt NewOffset = TypeSize * *C2 + *C1;
2614 if (NewOffset.isZero() ||
2615 (Src->hasOneUse() && GEP.getOperand(i_nocapture: 1)->hasOneUse())) {
2616 Value *GEPConst =
2617 IC.Builder.CreatePtrAdd(Ptr: Base, Offset: IC.Builder.getInt(AI: NewOffset));
2618 return GetElementPtrInst::Create(PointeeType: BaseType, Ptr: GEPConst, IdxList: VarIndex);
2619 }
2620
2621 return nullptr;
2622}
2623
2624Instruction *InstCombinerImpl::visitGEPOfGEP(GetElementPtrInst &GEP,
2625 GEPOperator *Src) {
2626 // Combine Indices - If the source pointer to this getelementptr instruction
2627 // is a getelementptr instruction with matching element type, combine the
2628 // indices of the two getelementptr instructions into a single instruction.
2629 if (!shouldMergeGEPs(GEP&: *cast<GEPOperator>(Val: &GEP), Src&: *Src))
2630 return nullptr;
2631
2632 if (auto *I = canonicalizeGEPOfConstGEPI8(GEP, Src, IC&: *this))
2633 return I;
2634
2635 // For constant GEPs, use a more general offset-based folding approach.
2636 Type *PtrTy = Src->getType()->getScalarType();
2637 if (GEP.hasAllConstantIndices() &&
2638 (Src->hasOneUse() || Src->hasAllConstantIndices())) {
2639 // Split Src into a variable part and a constant suffix.
2640 gep_type_iterator GTI = gep_type_begin(GEP: *Src);
2641 Type *BaseType = GTI.getIndexedType();
2642 bool IsFirstType = true;
2643 unsigned NumVarIndices = 0;
2644 for (auto Pair : enumerate(First: Src->indices())) {
2645 if (!isa<ConstantInt>(Val: Pair.value())) {
2646 BaseType = GTI.getIndexedType();
2647 IsFirstType = false;
2648 NumVarIndices = Pair.index() + 1;
2649 }
2650 ++GTI;
2651 }
2652
2653 // Determine the offset for the constant suffix of Src.
2654 APInt Offset(DL.getIndexTypeSizeInBits(Ty: PtrTy), 0);
2655 if (NumVarIndices != Src->getNumIndices()) {
2656 // FIXME: getIndexedOffsetInType() does not handled scalable vectors.
2657 if (BaseType->isScalableTy())
2658 return nullptr;
2659
2660 SmallVector<Value *> ConstantIndices;
2661 if (!IsFirstType)
2662 ConstantIndices.push_back(
2663 Elt: Constant::getNullValue(Ty: Type::getInt32Ty(C&: GEP.getContext())));
2664 append_range(C&: ConstantIndices, R: drop_begin(RangeOrContainer: Src->indices(), N: NumVarIndices));
2665 Offset += DL.getIndexedOffsetInType(ElemTy: BaseType, Indices: ConstantIndices);
2666 }
2667
2668 // Add the offset for GEP (which is fully constant).
2669 if (!GEP.accumulateConstantOffset(DL, Offset))
2670 return nullptr;
2671
2672 // Convert the total offset back into indices.
2673 SmallVector<APInt> ConstIndices =
2674 DL.getGEPIndicesForOffset(ElemTy&: BaseType, Offset);
2675 if (!Offset.isZero() || (!IsFirstType && !ConstIndices[0].isZero()))
2676 return nullptr;
2677
2678 GEPNoWrapFlags NW = getMergedGEPNoWrapFlags(GEP1&: *Src, GEP2&: *cast<GEPOperator>(Val: &GEP));
2679 SmallVector<Value *> Indices(
2680 drop_end(RangeOrContainer: Src->indices(), N: Src->getNumIndices() - NumVarIndices));
2681 for (const APInt &Idx : drop_begin(RangeOrContainer&: ConstIndices, N: !IsFirstType)) {
2682 Indices.push_back(Elt: ConstantInt::get(Context&: GEP.getContext(), V: Idx));
2683 // Even if the total offset is inbounds, we may end up representing it
2684 // by first performing a larger negative offset, and then a smaller
2685 // positive one. The large negative offset might go out of bounds. Only
2686 // preserve inbounds if all signs are the same.
2687 if (Idx.isNonNegative() != ConstIndices[0].isNonNegative())
2688 NW = NW.withoutNoUnsignedSignedWrap();
2689 if (!Idx.isNonNegative())
2690 NW = NW.withoutNoUnsignedWrap();
2691 }
2692
2693 return replaceInstUsesWith(
2694 I&: GEP, V: Builder.CreateGEP(Ty: Src->getSourceElementType(), Ptr: Src->getOperand(i_nocapture: 0),
2695 IdxList: Indices, Name: "", NW));
2696 }
2697
2698 if (Src->getResultElementType() != GEP.getSourceElementType())
2699 return nullptr;
2700
2701 SmallVector<Value*, 8> Indices;
2702
2703 // Find out whether the last index in the source GEP is a sequential idx.
2704 bool EndsWithSequential = false;
2705 for (gep_type_iterator I = gep_type_begin(GEP: *Src), E = gep_type_end(GEP: *Src);
2706 I != E; ++I)
2707 EndsWithSequential = I.isSequential();
2708
2709 // Can we combine the two pointer arithmetics offsets?
2710 if (EndsWithSequential) {
2711 // Replace: gep (gep %P, long B), long A, ...
2712 // With: T = long A+B; gep %P, T, ...
2713 Value *SO1 = Src->getOperand(i_nocapture: Src->getNumOperands()-1);
2714 Value *GO1 = GEP.getOperand(i_nocapture: 1);
2715
2716 // If they aren't the same type, then the input hasn't been processed
2717 // by the loop above yet (which canonicalizes sequential index types to
2718 // intptr_t). Just avoid transforming this until the input has been
2719 // normalized.
2720 if (SO1->getType() != GO1->getType())
2721 return nullptr;
2722
2723 Value *Sum =
2724 simplifyAddInst(LHS: GO1, RHS: SO1, IsNSW: false, IsNUW: false, Q: SQ.getWithInstruction(I: &GEP));
2725 // Only do the combine when we are sure the cost after the
2726 // merge is never more than that before the merge.
2727 if (Sum == nullptr)
2728 return nullptr;
2729
2730 Indices.append(in_start: Src->op_begin()+1, in_end: Src->op_end()-1);
2731 Indices.push_back(Elt: Sum);
2732 Indices.append(in_start: GEP.op_begin()+2, in_end: GEP.op_end());
2733 } else if (isa<Constant>(Val: *GEP.idx_begin()) &&
2734 cast<Constant>(Val&: *GEP.idx_begin())->isNullValue() &&
2735 Src->getNumOperands() != 1) {
2736 // Otherwise we can do the fold if the first index of the GEP is a zero
2737 Indices.append(in_start: Src->op_begin()+1, in_end: Src->op_end());
2738 Indices.append(in_start: GEP.idx_begin()+1, in_end: GEP.idx_end());
2739 }
2740
2741 if (!Indices.empty())
2742 return replaceInstUsesWith(
2743 I&: GEP, V: Builder.CreateGEP(
2744 Ty: Src->getSourceElementType(), Ptr: Src->getOperand(i_nocapture: 0), IdxList: Indices, Name: "",
2745 NW: getMergedGEPNoWrapFlags(GEP1&: *Src, GEP2&: *cast<GEPOperator>(Val: &GEP))));
2746
2747 return nullptr;
2748}
2749
2750Value *InstCombiner::getFreelyInvertedImpl(Value *V, bool WillInvertAllUses,
2751 BuilderTy *Builder,
2752 bool &DoesConsume, unsigned Depth) {
2753 static Value *const NonNull = reinterpret_cast<Value *>(uintptr_t(1));
2754 // ~(~(X)) -> X.
2755 Value *A, *B;
2756 if (match(V, P: m_Not(V: m_Value(V&: A)))) {
2757 DoesConsume = true;
2758 return A;
2759 }
2760
2761 Constant *C;
2762 // Constants can be considered to be not'ed values.
2763 if (match(V, P: m_ImmConstant(C)))
2764 return ConstantExpr::getNot(C);
2765
2766 if (Depth++ >= MaxAnalysisRecursionDepth)
2767 return nullptr;
2768
2769 // The rest of the cases require that we invert all uses so don't bother
2770 // doing the analysis if we know we can't use the result.
2771 if (!WillInvertAllUses)
2772 return nullptr;
2773
2774 // Compares can be inverted if all of their uses are being modified to use
2775 // the ~V.
2776 if (auto *I = dyn_cast<CmpInst>(Val: V)) {
2777 if (Builder != nullptr)
2778 return Builder->CreateCmp(Pred: I->getInversePredicate(), LHS: I->getOperand(i_nocapture: 0),
2779 RHS: I->getOperand(i_nocapture: 1));
2780 return NonNull;
2781 }
2782
2783 // If `V` is of the form `A + B` then `-1 - V` can be folded into
2784 // `(-1 - B) - A` if we are willing to invert all of the uses.
2785 if (match(V, P: m_Add(L: m_Value(V&: A), R: m_Value(V&: B)))) {
2786 if (auto *BV = getFreelyInvertedImpl(V: B, WillInvertAllUses: B->hasOneUse(), Builder,
2787 DoesConsume, Depth))
2788 return Builder ? Builder->CreateSub(LHS: BV, RHS: A) : NonNull;
2789 if (auto *AV = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2790 DoesConsume, Depth))
2791 return Builder ? Builder->CreateSub(LHS: AV, RHS: B) : NonNull;
2792 return nullptr;
2793 }
2794
2795 // If `V` is of the form `A ^ ~B` then `~(A ^ ~B)` can be folded
2796 // into `A ^ B` if we are willing to invert all of the uses.
2797 if (match(V, P: m_Xor(L: m_Value(V&: A), R: m_Value(V&: B)))) {
2798 if (auto *BV = getFreelyInvertedImpl(V: B, WillInvertAllUses: B->hasOneUse(), Builder,
2799 DoesConsume, Depth))
2800 return Builder ? Builder->CreateXor(LHS: A, RHS: BV) : NonNull;
2801 if (auto *AV = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2802 DoesConsume, Depth))
2803 return Builder ? Builder->CreateXor(LHS: AV, RHS: B) : NonNull;
2804 return nullptr;
2805 }
2806
2807 // If `V` is of the form `B - A` then `-1 - V` can be folded into
2808 // `A + (-1 - B)` if we are willing to invert all of the uses.
2809 if (match(V, P: m_Sub(L: m_Value(V&: A), R: m_Value(V&: B)))) {
2810 if (auto *AV = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2811 DoesConsume, Depth))
2812 return Builder ? Builder->CreateAdd(LHS: AV, RHS: B) : NonNull;
2813 return nullptr;
2814 }
2815
2816 // If `V` is of the form `(~A) s>> B` then `~((~A) s>> B)` can be folded
2817 // into `A s>> B` if we are willing to invert all of the uses.
2818 if (match(V, P: m_AShr(L: m_Value(V&: A), R: m_Value(V&: B)))) {
2819 if (auto *AV = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2820 DoesConsume, Depth))
2821 return Builder ? Builder->CreateAShr(LHS: AV, RHS: B) : NonNull;
2822 return nullptr;
2823 }
2824
2825 Value *Cond;
2826 // LogicOps are special in that we canonicalize them at the cost of an
2827 // instruction.
2828 bool IsSelect = match(V, P: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: A), R: m_Value(V&: B))) &&
2829 !shouldAvoidAbsorbingNotIntoSelect(SI: *cast<SelectInst>(Val: V));
2830 // Selects/min/max with invertible operands are freely invertible
2831 if (IsSelect || match(V, P: m_MaxOrMin(L: m_Value(V&: A), R: m_Value(V&: B)))) {
2832 bool LocalDoesConsume = DoesConsume;
2833 if (!getFreelyInvertedImpl(V: B, WillInvertAllUses: B->hasOneUse(), /*Builder*/ nullptr,
2834 DoesConsume&: LocalDoesConsume, Depth))
2835 return nullptr;
2836 if (Value *NotA = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2837 DoesConsume&: LocalDoesConsume, Depth)) {
2838 DoesConsume = LocalDoesConsume;
2839 if (Builder != nullptr) {
2840 Value *NotB = getFreelyInvertedImpl(V: B, WillInvertAllUses: B->hasOneUse(), Builder,
2841 DoesConsume, Depth);
2842 assert(NotB != nullptr &&
2843 "Unable to build inverted value for known freely invertable op");
2844 if (auto *II = dyn_cast<IntrinsicInst>(Val: V))
2845 return Builder->CreateBinaryIntrinsic(
2846 ID: getInverseMinMaxIntrinsic(MinMaxID: II->getIntrinsicID()), LHS: NotA, RHS: NotB);
2847 return Builder->CreateSelect(C: Cond, True: NotA, False: NotB);
2848 }
2849 return NonNull;
2850 }
2851 }
2852
2853 if (PHINode *PN = dyn_cast<PHINode>(Val: V)) {
2854 bool LocalDoesConsume = DoesConsume;
2855 SmallVector<std::pair<Value *, BasicBlock *>, 8> IncomingValues;
2856 for (Use &U : PN->operands()) {
2857 BasicBlock *IncomingBlock = PN->getIncomingBlock(U);
2858 Value *NewIncomingVal = getFreelyInvertedImpl(
2859 V: U.get(), /*WillInvertAllUses=*/false,
2860 /*Builder=*/nullptr, DoesConsume&: LocalDoesConsume, Depth: MaxAnalysisRecursionDepth - 1);
2861 if (NewIncomingVal == nullptr)
2862 return nullptr;
2863 // Make sure that we can safely erase the original PHI node.
2864 if (NewIncomingVal == V)
2865 return nullptr;
2866 if (Builder != nullptr)
2867 IncomingValues.emplace_back(Args&: NewIncomingVal, Args&: IncomingBlock);
2868 }
2869
2870 DoesConsume = LocalDoesConsume;
2871 if (Builder != nullptr) {
2872 IRBuilderBase::InsertPointGuard Guard(*Builder);
2873 Builder->SetInsertPoint(PN);
2874 PHINode *NewPN =
2875 Builder->CreatePHI(Ty: PN->getType(), NumReservedValues: PN->getNumIncomingValues());
2876 for (auto [Val, Pred] : IncomingValues)
2877 NewPN->addIncoming(V: Val, BB: Pred);
2878 return NewPN;
2879 }
2880 return NonNull;
2881 }
2882
2883 if (match(V, P: m_SExtLike(Op: m_Value(V&: A)))) {
2884 if (auto *AV = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2885 DoesConsume, Depth))
2886 return Builder ? Builder->CreateSExt(V: AV, DestTy: V->getType()) : NonNull;
2887 return nullptr;
2888 }
2889
2890 if (match(V, P: m_Trunc(Op: m_Value(V&: A)))) {
2891 if (auto *AV = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2892 DoesConsume, Depth))
2893 return Builder ? Builder->CreateTrunc(V: AV, DestTy: V->getType()) : NonNull;
2894 return nullptr;
2895 }
2896
2897 // De Morgan's Laws:
2898 // (~(A | B)) -> (~A & ~B)
2899 // (~(A & B)) -> (~A | ~B)
2900 auto TryInvertAndOrUsingDeMorgan = [&](Instruction::BinaryOps Opcode,
2901 bool IsLogical, Value *A,
2902 Value *B) -> Value * {
2903 bool LocalDoesConsume = DoesConsume;
2904 if (!getFreelyInvertedImpl(V: B, WillInvertAllUses: B->hasOneUse(), /*Builder=*/nullptr,
2905 DoesConsume&: LocalDoesConsume, Depth))
2906 return nullptr;
2907 if (auto *NotA = getFreelyInvertedImpl(V: A, WillInvertAllUses: A->hasOneUse(), Builder,
2908 DoesConsume&: LocalDoesConsume, Depth)) {
2909 auto *NotB = getFreelyInvertedImpl(V: B, WillInvertAllUses: B->hasOneUse(), Builder,
2910 DoesConsume&: LocalDoesConsume, Depth);
2911 DoesConsume = LocalDoesConsume;
2912 if (IsLogical)
2913 return Builder ? Builder->CreateLogicalOp(Opc: Opcode, Cond1: NotA, Cond2: NotB) : NonNull;
2914 return Builder ? Builder->CreateBinOp(Opc: Opcode, LHS: NotA, RHS: NotB) : NonNull;
2915 }
2916
2917 return nullptr;
2918 };
2919
2920 if (match(V, P: m_Or(L: m_Value(V&: A), R: m_Value(V&: B))))
2921 return TryInvertAndOrUsingDeMorgan(Instruction::And, /*IsLogical=*/false, A,
2922 B);
2923
2924 if (match(V, P: m_And(L: m_Value(V&: A), R: m_Value(V&: B))))
2925 return TryInvertAndOrUsingDeMorgan(Instruction::Or, /*IsLogical=*/false, A,
2926 B);
2927
2928 if (match(V, P: m_LogicalOr(L: m_Value(V&: A), R: m_Value(V&: B))))
2929 return TryInvertAndOrUsingDeMorgan(Instruction::And, /*IsLogical=*/true, A,
2930 B);
2931
2932 if (match(V, P: m_LogicalAnd(L: m_Value(V&: A), R: m_Value(V&: B))))
2933 return TryInvertAndOrUsingDeMorgan(Instruction::Or, /*IsLogical=*/true, A,
2934 B);
2935
2936 return nullptr;
2937}
2938
2939/// Return true if we should canonicalize the gep to an i8 ptradd.
2940static bool shouldCanonicalizeGEPToPtrAdd(GetElementPtrInst &GEP) {
2941 Value *PtrOp = GEP.getOperand(i_nocapture: 0);
2942 Type *GEPEltType = GEP.getSourceElementType();
2943 if (GEPEltType->isIntegerTy(Bitwidth: 8))
2944 return false;
2945
2946 // Canonicalize scalable GEPs to an explicit offset using the llvm.vscale
2947 // intrinsic. This has better support in BasicAA.
2948 if (GEPEltType->isScalableTy())
2949 return true;
2950
2951 // gep i32 p, mul(O, C) -> gep i8, p, mul(O, C*4) to fold the two multiplies
2952 // together.
2953 if (GEP.getNumIndices() == 1 &&
2954 match(V: GEP.getOperand(i_nocapture: 1),
2955 P: m_OneUse(SubPattern: m_CombineOr(L: m_Mul(L: m_Value(), R: m_ConstantInt()),
2956 R: m_Shl(L: m_Value(), R: m_ConstantInt())))))
2957 return true;
2958
2959 // gep (gep %p, C1), %x, C2 is expanded so the two constants can
2960 // possibly be merged together.
2961 auto PtrOpGep = dyn_cast<GEPOperator>(Val: PtrOp);
2962 return PtrOpGep && PtrOpGep->hasAllConstantIndices() &&
2963 any_of(Range: GEP.indices(), P: [](Value *V) {
2964 const APInt *C;
2965 return match(V, P: m_APInt(Res&: C)) && !C->isZero();
2966 });
2967}
2968
2969static Instruction *foldGEPOfPhi(GetElementPtrInst &GEP, PHINode *PN,
2970 IRBuilderBase &Builder) {
2971 auto *Op1 = dyn_cast<GetElementPtrInst>(Val: PN->getOperand(i_nocapture: 0));
2972 if (!Op1)
2973 return nullptr;
2974
2975 // Don't fold a GEP into itself through a PHI node. This can only happen
2976 // through the back-edge of a loop. Folding a GEP into itself means that
2977 // the value of the previous iteration needs to be stored in the meantime,
2978 // thus requiring an additional register variable to be live, but not
2979 // actually achieving anything (the GEP still needs to be executed once per
2980 // loop iteration).
2981 if (Op1 == &GEP)
2982 return nullptr;
2983 GEPNoWrapFlags NW = Op1->getNoWrapFlags();
2984
2985 int DI = -1;
2986
2987 for (auto I = PN->op_begin()+1, E = PN->op_end(); I !=E; ++I) {
2988 auto *Op2 = dyn_cast<GetElementPtrInst>(Val&: *I);
2989 if (!Op2 || Op1->getNumOperands() != Op2->getNumOperands() ||
2990 Op1->getSourceElementType() != Op2->getSourceElementType())
2991 return nullptr;
2992
2993 // As for Op1 above, don't try to fold a GEP into itself.
2994 if (Op2 == &GEP)
2995 return nullptr;
2996
2997 // Keep track of the type as we walk the GEP.
2998 Type *CurTy = nullptr;
2999
3000 for (unsigned J = 0, F = Op1->getNumOperands(); J != F; ++J) {
3001 if (Op1->getOperand(i_nocapture: J)->getType() != Op2->getOperand(i_nocapture: J)->getType())
3002 return nullptr;
3003
3004 if (Op1->getOperand(i_nocapture: J) != Op2->getOperand(i_nocapture: J)) {
3005 if (DI == -1) {
3006 // We have not seen any differences yet in the GEPs feeding the
3007 // PHI yet, so we record this one if it is allowed to be a
3008 // variable.
3009
3010 // The first two arguments can vary for any GEP, the rest have to be
3011 // static for struct slots
3012 if (J > 1) {
3013 assert(CurTy && "No current type?");
3014 if (CurTy->isStructTy())
3015 return nullptr;
3016 }
3017
3018 DI = J;
3019 } else {
3020 // The GEP is different by more than one input. While this could be
3021 // extended to support GEPs that vary by more than one variable it
3022 // doesn't make sense since it greatly increases the complexity and
3023 // would result in an R+R+R addressing mode which no backend
3024 // directly supports and would need to be broken into several
3025 // simpler instructions anyway.
3026 return nullptr;
3027 }
3028 }
3029
3030 // Sink down a layer of the type for the next iteration.
3031 if (J > 0) {
3032 if (J == 1) {
3033 CurTy = Op1->getSourceElementType();
3034 } else {
3035 CurTy =
3036 GetElementPtrInst::getTypeAtIndex(Ty: CurTy, Idx: Op1->getOperand(i_nocapture: J));
3037 }
3038 }
3039 }
3040
3041 NW &= Op2->getNoWrapFlags();
3042 }
3043
3044 // If not all GEPs are identical we'll have to create a new PHI node.
3045 // Check that the old PHI node has only one use so that it will get
3046 // removed.
3047 if (DI != -1 && !PN->hasOneUse())
3048 return nullptr;
3049
3050 auto *NewGEP = cast<GetElementPtrInst>(Val: Op1->clone());
3051 NewGEP->setNoWrapFlags(NW);
3052
3053 if (DI == -1) {
3054 // All the GEPs feeding the PHI are identical. Clone one down into our
3055 // BB so that it can be merged with the current GEP.
3056 } else {
3057 // All the GEPs feeding the PHI differ at a single offset. Clone a GEP
3058 // into the current block so it can be merged, and create a new PHI to
3059 // set that index.
3060 PHINode *NewPN;
3061 {
3062 IRBuilderBase::InsertPointGuard Guard(Builder);
3063 Builder.SetInsertPoint(PN);
3064 NewPN = Builder.CreatePHI(Ty: Op1->getOperand(i_nocapture: DI)->getType(),
3065 NumReservedValues: PN->getNumOperands());
3066 }
3067
3068 for (auto &I : PN->operands())
3069 NewPN->addIncoming(V: cast<GEPOperator>(Val&: I)->getOperand(i_nocapture: DI),
3070 BB: PN->getIncomingBlock(U: I));
3071
3072 NewGEP->setOperand(i_nocapture: DI, Val_nocapture: NewPN);
3073 }
3074
3075 NewGEP->insertBefore(BB&: *GEP.getParent(), InsertPos: GEP.getParent()->getFirstInsertionPt());
3076 return NewGEP;
3077}
3078
3079Instruction *InstCombinerImpl::visitGetElementPtrInst(GetElementPtrInst &GEP) {
3080 Value *PtrOp = GEP.getOperand(i_nocapture: 0);
3081 SmallVector<Value *, 8> Indices(GEP.indices());
3082 Type *GEPType = GEP.getType();
3083 Type *GEPEltType = GEP.getSourceElementType();
3084 if (Value *V =
3085 simplifyGEPInst(SrcTy: GEPEltType, Ptr: PtrOp, Indices, NW: GEP.getNoWrapFlags(),
3086 Q: SQ.getWithInstruction(I: &GEP)))
3087 return replaceInstUsesWith(I&: GEP, V);
3088
3089 // For vector geps, use the generic demanded vector support.
3090 // Skip if GEP return type is scalable. The number of elements is unknown at
3091 // compile-time.
3092 if (auto *GEPFVTy = dyn_cast<FixedVectorType>(Val: GEPType)) {
3093 auto VWidth = GEPFVTy->getNumElements();
3094 APInt PoisonElts(VWidth, 0);
3095 APInt AllOnesEltMask(APInt::getAllOnes(numBits: VWidth));
3096 if (Value *V = SimplifyDemandedVectorElts(V: &GEP, DemandedElts: AllOnesEltMask,
3097 PoisonElts)) {
3098 if (V != &GEP)
3099 return replaceInstUsesWith(I&: GEP, V);
3100 return &GEP;
3101 }
3102 }
3103
3104 // Eliminate unneeded casts for indices, and replace indices which displace
3105 // by multiples of a zero size type with zero.
3106 bool MadeChange = false;
3107
3108 // Index width may not be the same width as pointer width.
3109 // Data layout chooses the right type based on supported integer types.
3110 Type *NewScalarIndexTy =
3111 DL.getIndexType(PtrTy: GEP.getPointerOperandType()->getScalarType());
3112
3113 gep_type_iterator GTI = gep_type_begin(GEP);
3114 for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end(); I != E;
3115 ++I, ++GTI) {
3116 // Skip indices into struct types.
3117 if (GTI.isStruct())
3118 continue;
3119
3120 Type *IndexTy = (*I)->getType();
3121 Type *NewIndexType =
3122 IndexTy->isVectorTy()
3123 ? VectorType::get(ElementType: NewScalarIndexTy,
3124 EC: cast<VectorType>(Val: IndexTy)->getElementCount())
3125 : NewScalarIndexTy;
3126
3127 // If the element type has zero size then any index over it is equivalent
3128 // to an index of zero, so replace it with zero if it is not zero already.
3129 Type *EltTy = GTI.getIndexedType();
3130 if (EltTy->isSized() && DL.getTypeAllocSize(Ty: EltTy).isZero())
3131 if (!isa<Constant>(Val: *I) || !match(V: I->get(), P: m_Zero())) {
3132 *I = Constant::getNullValue(Ty: NewIndexType);
3133 MadeChange = true;
3134 }
3135
3136 if (IndexTy != NewIndexType) {
3137 // If we are using a wider index than needed for this platform, shrink
3138 // it to what we need. If narrower, sign-extend it to what we need.
3139 // This explicit cast can make subsequent optimizations more obvious.
3140 *I = Builder.CreateIntCast(V: *I, DestTy: NewIndexType, isSigned: true);
3141 MadeChange = true;
3142 }
3143 }
3144 if (MadeChange)
3145 return &GEP;
3146
3147 // Canonicalize constant GEPs to i8 type.
3148 if (!GEPEltType->isIntegerTy(Bitwidth: 8) && GEP.hasAllConstantIndices()) {
3149 APInt Offset(DL.getIndexTypeSizeInBits(Ty: GEPType), 0);
3150 if (GEP.accumulateConstantOffset(DL, Offset))
3151 return replaceInstUsesWith(
3152 I&: GEP, V: Builder.CreatePtrAdd(Ptr: PtrOp, Offset: Builder.getInt(AI: Offset), Name: "",
3153 NW: GEP.getNoWrapFlags()));
3154 }
3155
3156 if (shouldCanonicalizeGEPToPtrAdd(GEP)) {
3157 Value *Offset = EmitGEPOffset(GEP: cast<GEPOperator>(Val: &GEP));
3158 Value *NewGEP =
3159 Builder.CreatePtrAdd(Ptr: PtrOp, Offset, Name: "", NW: GEP.getNoWrapFlags());
3160 return replaceInstUsesWith(I&: GEP, V: NewGEP);
3161 }
3162
3163 // Scalarize vector operands; prefer splat-of-gep.as canonical form.
3164 // Note that this looses information about undef lanes; we run it after
3165 // demanded bits to partially mitigate that loss.
3166 if (GEPType->isVectorTy() && llvm::any_of(Range: GEP.operands(), P: [](Value *Op) {
3167 return Op->getType()->isVectorTy() && getSplatValue(V: Op);
3168 })) {
3169 SmallVector<Value *> NewOps;
3170 for (auto &Op : GEP.operands()) {
3171 if (Op->getType()->isVectorTy())
3172 if (Value *Scalar = getSplatValue(V: Op)) {
3173 NewOps.push_back(Elt: Scalar);
3174 continue;
3175 }
3176 NewOps.push_back(Elt: Op);
3177 }
3178
3179 Value *Res = Builder.CreateGEP(Ty: GEP.getSourceElementType(), Ptr: NewOps[0],
3180 IdxList: ArrayRef(NewOps).drop_front(), Name: GEP.getName(),
3181 NW: GEP.getNoWrapFlags());
3182 if (!Res->getType()->isVectorTy()) {
3183 ElementCount EC = cast<VectorType>(Val: GEPType)->getElementCount();
3184 Res = Builder.CreateVectorSplat(EC, V: Res);
3185 }
3186 return replaceInstUsesWith(I&: GEP, V: Res);
3187 }
3188
3189 // Check to see if the inputs to the PHI node are getelementptr instructions.
3190 if (auto *PN = dyn_cast<PHINode>(Val: PtrOp)) {
3191 if (Value *NewPtrOp = foldGEPOfPhi(GEP, PN, Builder))
3192 return replaceOperand(I&: GEP, OpNum: 0, V: NewPtrOp);
3193 }
3194
3195 if (auto *Src = dyn_cast<GEPOperator>(Val: PtrOp))
3196 if (Instruction *I = visitGEPOfGEP(GEP, Src))
3197 return I;
3198
3199 if (GEP.getNumIndices() == 1) {
3200 unsigned AS = GEP.getPointerAddressSpace();
3201 if (GEP.getOperand(i_nocapture: 1)->getType()->getScalarSizeInBits() ==
3202 DL.getIndexSizeInBits(AS)) {
3203 uint64_t TyAllocSize = DL.getTypeAllocSize(Ty: GEPEltType).getFixedValue();
3204
3205 if (TyAllocSize == 1) {
3206 // Canonicalize (gep i8* X, (ptrtoint Y)-(ptrtoint X)) to (bitcast Y),
3207 // but only if the result pointer is only used as if it were an integer,
3208 // or both point to the same underlying object (otherwise provenance is
3209 // not necessarily retained).
3210 Value *X = GEP.getPointerOperand();
3211 Value *Y;
3212 if (match(V: GEP.getOperand(i_nocapture: 1),
3213 P: m_Sub(L: m_PtrToInt(Op: m_Value(V&: Y)), R: m_PtrToInt(Op: m_Specific(V: X)))) &&
3214 GEPType == Y->getType()) {
3215 bool HasSameUnderlyingObject =
3216 getUnderlyingObject(V: X) == getUnderlyingObject(V: Y);
3217 bool Changed = false;
3218 GEP.replaceUsesWithIf(New: Y, ShouldReplace: [&](Use &U) {
3219 bool ShouldReplace = HasSameUnderlyingObject ||
3220 isa<ICmpInst>(Val: U.getUser()) ||
3221 isa<PtrToIntInst>(Val: U.getUser());
3222 Changed |= ShouldReplace;
3223 return ShouldReplace;
3224 });
3225 return Changed ? &GEP : nullptr;
3226 }
3227 } else if (auto *ExactIns =
3228 dyn_cast<PossiblyExactOperator>(Val: GEP.getOperand(i_nocapture: 1))) {
3229 // Canonicalize (gep T* X, V / sizeof(T)) to (gep i8* X, V)
3230 Value *V;
3231 if (ExactIns->isExact()) {
3232 if ((has_single_bit(Value: TyAllocSize) &&
3233 match(V: GEP.getOperand(i_nocapture: 1),
3234 P: m_Shr(L: m_Value(V),
3235 R: m_SpecificInt(V: countr_zero(Val: TyAllocSize))))) ||
3236 match(V: GEP.getOperand(i_nocapture: 1),
3237 P: m_IDiv(L: m_Value(V), R: m_SpecificInt(V: TyAllocSize)))) {
3238 return GetElementPtrInst::Create(PointeeType: Builder.getInt8Ty(),
3239 Ptr: GEP.getPointerOperand(), IdxList: V,
3240 NW: GEP.getNoWrapFlags());
3241 }
3242 }
3243 if (ExactIns->isExact() && ExactIns->hasOneUse()) {
3244 // Try to canonicalize non-i8 element type to i8 if the index is an
3245 // exact instruction. If the index is an exact instruction (div/shr)
3246 // with a constant RHS, we can fold the non-i8 element scale into the
3247 // div/shr (similiar to the mul case, just inverted).
3248 const APInt *C;
3249 std::optional<APInt> NewC;
3250 if (has_single_bit(Value: TyAllocSize) &&
3251 match(V: ExactIns, P: m_Shr(L: m_Value(V), R: m_APInt(Res&: C))) &&
3252 C->uge(RHS: countr_zero(Val: TyAllocSize)))
3253 NewC = *C - countr_zero(Val: TyAllocSize);
3254 else if (match(V: ExactIns, P: m_UDiv(L: m_Value(V), R: m_APInt(Res&: C)))) {
3255 APInt Quot;
3256 uint64_t Rem;
3257 APInt::udivrem(LHS: *C, RHS: TyAllocSize, Quotient&: Quot, Remainder&: Rem);
3258 if (Rem == 0)
3259 NewC = Quot;
3260 } else if (match(V: ExactIns, P: m_SDiv(L: m_Value(V), R: m_APInt(Res&: C)))) {
3261 APInt Quot;
3262 int64_t Rem;
3263 APInt::sdivrem(LHS: *C, RHS: TyAllocSize, Quotient&: Quot, Remainder&: Rem);
3264 // For sdiv we need to make sure we arent creating INT_MIN / -1.
3265 if (!Quot.isAllOnes() && Rem == 0)
3266 NewC = Quot;
3267 }
3268
3269 if (NewC.has_value()) {
3270 Value *NewOp = Builder.CreateBinOp(
3271 Opc: static_cast<Instruction::BinaryOps>(ExactIns->getOpcode()), LHS: V,
3272 RHS: ConstantInt::get(Ty: V->getType(), V: *NewC));
3273 cast<BinaryOperator>(Val: NewOp)->setIsExact();
3274 return GetElementPtrInst::Create(PointeeType: Builder.getInt8Ty(),
3275 Ptr: GEP.getPointerOperand(), IdxList: NewOp,
3276 NW: GEP.getNoWrapFlags());
3277 }
3278 }
3279 }
3280 }
3281 }
3282 // We do not handle pointer-vector geps here.
3283 if (GEPType->isVectorTy())
3284 return nullptr;
3285
3286 if (!GEP.isInBounds()) {
3287 unsigned IdxWidth =
3288 DL.getIndexSizeInBits(AS: PtrOp->getType()->getPointerAddressSpace());
3289 APInt BasePtrOffset(IdxWidth, 0);
3290 Value *UnderlyingPtrOp =
3291 PtrOp->stripAndAccumulateInBoundsConstantOffsets(DL, Offset&: BasePtrOffset);
3292 bool CanBeNull, CanBeFreed;
3293 uint64_t DerefBytes = UnderlyingPtrOp->getPointerDereferenceableBytes(
3294 DL, CanBeNull, CanBeFreed);
3295 if (!CanBeNull && !CanBeFreed && DerefBytes != 0) {
3296 if (GEP.accumulateConstantOffset(DL, Offset&: BasePtrOffset) &&
3297 BasePtrOffset.isNonNegative()) {
3298 APInt AllocSize(IdxWidth, DerefBytes);
3299 if (BasePtrOffset.ule(RHS: AllocSize)) {
3300 return GetElementPtrInst::CreateInBounds(
3301 PointeeType: GEP.getSourceElementType(), Ptr: PtrOp, IdxList: Indices, NameStr: GEP.getName());
3302 }
3303 }
3304 }
3305 }
3306
3307 // nusw + nneg -> nuw
3308 if (GEP.hasNoUnsignedSignedWrap() && !GEP.hasNoUnsignedWrap() &&
3309 all_of(Range: GEP.indices(), P: [&](Value *Idx) {
3310 return isKnownNonNegative(V: Idx, SQ: SQ.getWithInstruction(I: &GEP));
3311 })) {
3312 GEP.setNoWrapFlags(GEP.getNoWrapFlags() | GEPNoWrapFlags::noUnsignedWrap());
3313 return &GEP;
3314 }
3315
3316 // These rewrites are trying to preserve inbounds/nuw attributes. So we want
3317 // to do this after having tried to derive "nuw" above.
3318 if (GEP.getNumIndices() == 1) {
3319 // Given (gep p, x+y) we want to determine the common nowrap flags for both
3320 // geps if transforming into (gep (gep p, x), y).
3321 auto GetPreservedNoWrapFlags = [&](bool AddIsNUW) {
3322 // We can preserve both "inbounds nuw", "nusw nuw" and "nuw" if we know
3323 // that x + y does not have unsigned wrap.
3324 if (GEP.hasNoUnsignedWrap() && AddIsNUW)
3325 return GEP.getNoWrapFlags();
3326 return GEPNoWrapFlags::none();
3327 };
3328
3329 // Try to replace ADD + GEP with GEP + GEP.
3330 Value *Idx1, *Idx2;
3331 if (match(V: GEP.getOperand(i_nocapture: 1),
3332 P: m_OneUse(SubPattern: m_AddLike(L: m_Value(V&: Idx1), R: m_Value(V&: Idx2))))) {
3333 // %idx = add i64 %idx1, %idx2
3334 // %gep = getelementptr i32, ptr %ptr, i64 %idx
3335 // as:
3336 // %newptr = getelementptr i32, ptr %ptr, i64 %idx1
3337 // %newgep = getelementptr i32, ptr %newptr, i64 %idx2
3338 bool NUW = match(V: GEP.getOperand(i_nocapture: 1), P: m_NUWAddLike(L: m_Value(), R: m_Value()));
3339 GEPNoWrapFlags NWFlags = GetPreservedNoWrapFlags(NUW);
3340 auto *NewPtr =
3341 Builder.CreateGEP(Ty: GEP.getSourceElementType(), Ptr: GEP.getPointerOperand(),
3342 IdxList: Idx1, Name: "", NW: NWFlags);
3343 return replaceInstUsesWith(I&: GEP,
3344 V: Builder.CreateGEP(Ty: GEP.getSourceElementType(),
3345 Ptr: NewPtr, IdxList: Idx2, Name: "", NW: NWFlags));
3346 }
3347 ConstantInt *C;
3348 if (match(V: GEP.getOperand(i_nocapture: 1), P: m_OneUse(SubPattern: m_SExtLike(Op: m_OneUse(SubPattern: m_NSWAddLike(
3349 L: m_Value(V&: Idx1), R: m_ConstantInt(CI&: C))))))) {
3350 // %add = add nsw i32 %idx1, idx2
3351 // %sidx = sext i32 %add to i64
3352 // %gep = getelementptr i32, ptr %ptr, i64 %sidx
3353 // as:
3354 // %newptr = getelementptr i32, ptr %ptr, i32 %idx1
3355 // %newgep = getelementptr i32, ptr %newptr, i32 idx2
3356 bool NUW = match(V: GEP.getOperand(i_nocapture: 1),
3357 P: m_NNegZExt(Op: m_NUWAddLike(L: m_Value(), R: m_Value())));
3358 GEPNoWrapFlags NWFlags = GetPreservedNoWrapFlags(NUW);
3359 auto *NewPtr = Builder.CreateGEP(
3360 Ty: GEP.getSourceElementType(), Ptr: GEP.getPointerOperand(),
3361 IdxList: Builder.CreateSExt(V: Idx1, DestTy: GEP.getOperand(i_nocapture: 1)->getType()), Name: "", NW: NWFlags);
3362 return replaceInstUsesWith(
3363 I&: GEP,
3364 V: Builder.CreateGEP(Ty: GEP.getSourceElementType(), Ptr: NewPtr,
3365 IdxList: Builder.CreateSExt(V: C, DestTy: GEP.getOperand(i_nocapture: 1)->getType()),
3366 Name: "", NW: NWFlags));
3367 }
3368 }
3369
3370 if (Instruction *R = foldSelectGEP(GEP, Builder))
3371 return R;
3372
3373 return nullptr;
3374}
3375
3376static bool isNeverEqualToUnescapedAlloc(Value *V, const TargetLibraryInfo &TLI,
3377 Instruction *AI) {
3378 if (isa<ConstantPointerNull>(Val: V))
3379 return true;
3380 if (auto *LI = dyn_cast<LoadInst>(Val: V))
3381 return isa<GlobalVariable>(Val: LI->getPointerOperand());
3382 // Two distinct allocations will never be equal.
3383 return isAllocLikeFn(V, TLI: &TLI) && V != AI;
3384}
3385
3386/// Given a call CB which uses an address UsedV, return true if we can prove the
3387/// call's only possible effect is storing to V.
3388static bool isRemovableWrite(CallBase &CB, Value *UsedV,
3389 const TargetLibraryInfo &TLI) {
3390 if (!CB.use_empty())
3391 // TODO: add recursion if returned attribute is present
3392 return false;
3393
3394 if (CB.isTerminator())
3395 // TODO: remove implementation restriction
3396 return false;
3397
3398 if (!CB.willReturn() || !CB.doesNotThrow())
3399 return false;
3400
3401 // If the only possible side effect of the call is writing to the alloca,
3402 // and the result isn't used, we can safely remove any reads implied by the
3403 // call including those which might read the alloca itself.
3404 std::optional<MemoryLocation> Dest = MemoryLocation::getForDest(CI: &CB, TLI);
3405 return Dest && Dest->Ptr == UsedV;
3406}
3407
3408static std::optional<ModRefInfo>
3409isAllocSiteRemovable(Instruction *AI, SmallVectorImpl<WeakTrackingVH> &Users,
3410 const TargetLibraryInfo &TLI, bool KnowInit) {
3411 SmallVector<Instruction*, 4> Worklist;
3412 const std::optional<StringRef> Family = getAllocationFamily(I: AI, TLI: &TLI);
3413 Worklist.push_back(Elt: AI);
3414 ModRefInfo Access = KnowInit ? ModRefInfo::NoModRef : ModRefInfo::Mod;
3415
3416 do {
3417 Instruction *PI = Worklist.pop_back_val();
3418 for (User *U : PI->users()) {
3419 Instruction *I = cast<Instruction>(Val: U);
3420 switch (I->getOpcode()) {
3421 default:
3422 // Give up the moment we see something we can't handle.
3423 return std::nullopt;
3424
3425 case Instruction::AddrSpaceCast:
3426 case Instruction::BitCast:
3427 case Instruction::GetElementPtr:
3428 Users.emplace_back(Args&: I);
3429 Worklist.push_back(Elt: I);
3430 continue;
3431
3432 case Instruction::ICmp: {
3433 ICmpInst *ICI = cast<ICmpInst>(Val: I);
3434 // We can fold eq/ne comparisons with null to false/true, respectively.
3435 // We also fold comparisons in some conditions provided the alloc has
3436 // not escaped (see isNeverEqualToUnescapedAlloc).
3437 if (!ICI->isEquality())
3438 return std::nullopt;
3439 unsigned OtherIndex = (ICI->getOperand(i_nocapture: 0) == PI) ? 1 : 0;
3440 if (!isNeverEqualToUnescapedAlloc(V: ICI->getOperand(i_nocapture: OtherIndex), TLI, AI))
3441 return std::nullopt;
3442
3443 // Do not fold compares to aligned_alloc calls, as they may have to
3444 // return null in case the required alignment cannot be satisfied,
3445 // unless we can prove that both alignment and size are valid.
3446 auto AlignmentAndSizeKnownValid = [](CallBase *CB) {
3447 // Check if alignment and size of a call to aligned_alloc is valid,
3448 // that is alignment is a power-of-2 and the size is a multiple of the
3449 // alignment.
3450 const APInt *Alignment;
3451 const APInt *Size;
3452 return match(V: CB->getArgOperand(i: 0), P: m_APInt(Res&: Alignment)) &&
3453 match(V: CB->getArgOperand(i: 1), P: m_APInt(Res&: Size)) &&
3454 Alignment->isPowerOf2() && Size->urem(RHS: *Alignment).isZero();
3455 };
3456 auto *CB = dyn_cast<CallBase>(Val: AI);
3457 LibFunc TheLibFunc;
3458 if (CB && TLI.getLibFunc(FDecl: *CB->getCalledFunction(), F&: TheLibFunc) &&
3459 TLI.has(F: TheLibFunc) && TheLibFunc == LibFunc_aligned_alloc &&
3460 !AlignmentAndSizeKnownValid(CB))
3461 return std::nullopt;
3462 Users.emplace_back(Args&: I);
3463 continue;
3464 }
3465
3466 case Instruction::Call:
3467 // Ignore no-op and store intrinsics.
3468 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
3469 switch (II->getIntrinsicID()) {
3470 default:
3471 return std::nullopt;
3472
3473 case Intrinsic::memmove:
3474 case Intrinsic::memcpy:
3475 case Intrinsic::memset: {
3476 MemIntrinsic *MI = cast<MemIntrinsic>(Val: II);
3477 if (MI->isVolatile())
3478 return std::nullopt;
3479 // Note: this could also be ModRef, but we can still interpret that
3480 // as just Mod in that case.
3481 ModRefInfo NewAccess =
3482 MI->getRawDest() == PI ? ModRefInfo::Mod : ModRefInfo::Ref;
3483 if ((Access & ~NewAccess) != ModRefInfo::NoModRef)
3484 return std::nullopt;
3485 Access |= NewAccess;
3486 [[fallthrough]];
3487 }
3488 case Intrinsic::assume:
3489 case Intrinsic::invariant_start:
3490 case Intrinsic::invariant_end:
3491 case Intrinsic::lifetime_start:
3492 case Intrinsic::lifetime_end:
3493 case Intrinsic::objectsize:
3494 Users.emplace_back(Args&: I);
3495 continue;
3496 case Intrinsic::launder_invariant_group:
3497 case Intrinsic::strip_invariant_group:
3498 Users.emplace_back(Args&: I);
3499 Worklist.push_back(Elt: I);
3500 continue;
3501 }
3502 }
3503
3504 if (Family && getFreedOperand(CB: cast<CallBase>(Val: I), TLI: &TLI) == PI &&
3505 getAllocationFamily(I, TLI: &TLI) == Family) {
3506 Users.emplace_back(Args&: I);
3507 continue;
3508 }
3509
3510 if (Family && getReallocatedOperand(CB: cast<CallBase>(Val: I)) == PI &&
3511 getAllocationFamily(I, TLI: &TLI) == Family) {
3512 Users.emplace_back(Args&: I);
3513 Worklist.push_back(Elt: I);
3514 continue;
3515 }
3516
3517 if (!isRefSet(MRI: Access) &&
3518 isRemovableWrite(CB&: *cast<CallBase>(Val: I), UsedV: PI, TLI)) {
3519 Access |= ModRefInfo::Mod;
3520 Users.emplace_back(Args&: I);
3521 continue;
3522 }
3523
3524 return std::nullopt;
3525
3526 case Instruction::Store: {
3527 StoreInst *SI = cast<StoreInst>(Val: I);
3528 if (SI->isVolatile() || SI->getPointerOperand() != PI)
3529 return std::nullopt;
3530 if (isRefSet(MRI: Access))
3531 return std::nullopt;
3532 Access |= ModRefInfo::Mod;
3533 Users.emplace_back(Args&: I);
3534 continue;
3535 }
3536
3537 case Instruction::Load: {
3538 LoadInst *LI = cast<LoadInst>(Val: I);
3539 if (LI->isVolatile() || LI->getPointerOperand() != PI)
3540 return std::nullopt;
3541 if (isModSet(MRI: Access))
3542 return std::nullopt;
3543 Access |= ModRefInfo::Ref;
3544 Users.emplace_back(Args&: I);
3545 continue;
3546 }
3547 }
3548 llvm_unreachable("missing a return?");
3549 }
3550 } while (!Worklist.empty());
3551
3552 assert(Access != ModRefInfo::ModRef);
3553 return Access;
3554}
3555
3556Instruction *InstCombinerImpl::visitAllocSite(Instruction &MI) {
3557 assert(isa<AllocaInst>(MI) || isRemovableAlloc(&cast<CallBase>(MI), &TLI));
3558
3559 // If we have a malloc call which is only used in any amount of comparisons to
3560 // null and free calls, delete the calls and replace the comparisons with true
3561 // or false as appropriate.
3562
3563 // This is based on the principle that we can substitute our own allocation
3564 // function (which will never return null) rather than knowledge of the
3565 // specific function being called. In some sense this can change the permitted
3566 // outputs of a program (when we convert a malloc to an alloca, the fact that
3567 // the allocation is now on the stack is potentially visible, for example),
3568 // but we believe in a permissible manner.
3569 SmallVector<WeakTrackingVH, 64> Users;
3570
3571 // If we are removing an alloca with a dbg.declare, insert dbg.value calls
3572 // before each store.
3573 SmallVector<DbgVariableIntrinsic *, 8> DVIs;
3574 SmallVector<DbgVariableRecord *, 8> DVRs;
3575 std::unique_ptr<DIBuilder> DIB;
3576 if (isa<AllocaInst>(Val: MI)) {
3577 findDbgUsers(DbgInsts&: DVIs, V: &MI, DbgVariableRecords: &DVRs);
3578 DIB.reset(p: new DIBuilder(*MI.getModule(), /*AllowUnresolved=*/false));
3579 }
3580
3581 // Determine what getInitialValueOfAllocation would return without actually
3582 // allocating the result.
3583 bool KnowInitUndef = false;
3584 bool KnowInitZero = false;
3585 Constant *Init =
3586 getInitialValueOfAllocation(V: &MI, TLI: &TLI, Ty: Type::getInt8Ty(C&: MI.getContext()));
3587 if (Init) {
3588 if (isa<UndefValue>(Val: Init))
3589 KnowInitUndef = true;
3590 else if (Init->isNullValue())
3591 KnowInitZero = true;
3592 }
3593 // The various sanitizers don't actually return undef memory, but rather
3594 // memory initialized with special forms of runtime poison
3595 auto &F = *MI.getFunction();
3596 if (F.hasFnAttribute(Kind: Attribute::SanitizeMemory) ||
3597 F.hasFnAttribute(Kind: Attribute::SanitizeAddress))
3598 KnowInitUndef = false;
3599
3600 auto Removable =
3601 isAllocSiteRemovable(AI: &MI, Users, TLI, KnowInit: KnowInitZero | KnowInitUndef);
3602 if (Removable) {
3603 for (WeakTrackingVH &User : Users) {
3604 // Lowering all @llvm.objectsize and MTI calls first because they may use
3605 // a bitcast/GEP of the alloca we are removing.
3606 if (!User)
3607 continue;
3608
3609 Instruction *I = cast<Instruction>(Val: &*User);
3610
3611 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
3612 if (II->getIntrinsicID() == Intrinsic::objectsize) {
3613 SmallVector<Instruction *> InsertedInstructions;
3614 Value *Result = lowerObjectSizeCall(
3615 ObjectSize: II, DL, TLI: &TLI, AA, /*MustSucceed=*/true, InsertedInstructions: &InsertedInstructions);
3616 for (Instruction *Inserted : InsertedInstructions)
3617 Worklist.add(I: Inserted);
3618 replaceInstUsesWith(I&: *I, V: Result);
3619 eraseInstFromFunction(I&: *I);
3620 User = nullptr; // Skip examining in the next loop.
3621 continue;
3622 }
3623 if (auto *MTI = dyn_cast<MemTransferInst>(Val: I)) {
3624 if (KnowInitZero && isRefSet(MRI: *Removable)) {
3625 IRBuilderBase::InsertPointGuard Guard(Builder);
3626 Builder.SetInsertPoint(MTI);
3627 auto *M = Builder.CreateMemSet(
3628 Ptr: MTI->getRawDest(),
3629 Val: ConstantInt::get(Ty: Type::getInt8Ty(C&: MI.getContext()), V: 0),
3630 Size: MTI->getLength(), Align: MTI->getDestAlign());
3631 M->copyMetadata(SrcInst: *MTI);
3632 }
3633 }
3634 }
3635 }
3636 for (WeakTrackingVH &User : Users) {
3637 if (!User)
3638 continue;
3639
3640 Instruction *I = cast<Instruction>(Val: &*User);
3641
3642 if (ICmpInst *C = dyn_cast<ICmpInst>(Val: I)) {
3643 replaceInstUsesWith(I&: *C,
3644 V: ConstantInt::get(Ty: Type::getInt1Ty(C&: C->getContext()),
3645 V: C->isFalseWhenEqual()));
3646 } else if (auto *SI = dyn_cast<StoreInst>(Val: I)) {
3647 for (auto *DVI : DVIs)
3648 if (DVI->isAddressOfVariable())
3649 ConvertDebugDeclareToDebugValue(DII: DVI, SI, Builder&: *DIB);
3650 for (auto *DVR : DVRs)
3651 if (DVR->isAddressOfVariable())
3652 ConvertDebugDeclareToDebugValue(DVR, SI, Builder&: *DIB);
3653 } else {
3654 // Casts, GEP, or anything else: we're about to delete this instruction,
3655 // so it can not have any valid uses.
3656 Constant *Replace;
3657 if (isa<LoadInst>(Val: I)) {
3658 assert(KnowInitZero || KnowInitUndef);
3659 Replace = KnowInitUndef ? UndefValue::get(T: I->getType())
3660 : Constant::getNullValue(Ty: I->getType());
3661 } else
3662 Replace = PoisonValue::get(T: I->getType());
3663 replaceInstUsesWith(I&: *I, V: Replace);
3664 }
3665 eraseInstFromFunction(I&: *I);
3666 }
3667
3668 if (InvokeInst *II = dyn_cast<InvokeInst>(Val: &MI)) {
3669 // Replace invoke with a NOP intrinsic to maintain the original CFG
3670 Module *M = II->getModule();
3671 Function *F = Intrinsic::getOrInsertDeclaration(M, id: Intrinsic::donothing);
3672 auto *NewII = InvokeInst::Create(
3673 Func: F, IfNormal: II->getNormalDest(), IfException: II->getUnwindDest(), Args: {}, NameStr: "", InsertBefore: II->getParent());
3674 NewII->setDebugLoc(II->getDebugLoc());
3675 }
3676
3677 // Remove debug intrinsics which describe the value contained within the
3678 // alloca. In addition to removing dbg.{declare,addr} which simply point to
3679 // the alloca, remove dbg.value(<alloca>, ..., DW_OP_deref)'s as well, e.g.:
3680 //
3681 // ```
3682 // define void @foo(i32 %0) {
3683 // %a = alloca i32 ; Deleted.
3684 // store i32 %0, i32* %a
3685 // dbg.value(i32 %0, "arg0") ; Not deleted.
3686 // dbg.value(i32* %a, "arg0", DW_OP_deref) ; Deleted.
3687 // call void @trivially_inlinable_no_op(i32* %a)
3688 // ret void
3689 // }
3690 // ```
3691 //
3692 // This may not be required if we stop describing the contents of allocas
3693 // using dbg.value(<alloca>, ..., DW_OP_deref), but we currently do this in
3694 // the LowerDbgDeclare utility.
3695 //
3696 // If there is a dead store to `%a` in @trivially_inlinable_no_op, the
3697 // "arg0" dbg.value may be stale after the call. However, failing to remove
3698 // the DW_OP_deref dbg.value causes large gaps in location coverage.
3699 //
3700 // FIXME: the Assignment Tracking project has now likely made this
3701 // redundant (and it's sometimes harmful).
3702 for (auto *DVI : DVIs)
3703 if (DVI->isAddressOfVariable() || DVI->getExpression()->startsWithDeref())
3704 DVI->eraseFromParent();
3705 for (auto *DVR : DVRs)
3706 if (DVR->isAddressOfVariable() || DVR->getExpression()->startsWithDeref())
3707 DVR->eraseFromParent();
3708
3709 return eraseInstFromFunction(I&: MI);
3710 }
3711 return nullptr;
3712}
3713
3714/// Move the call to free before a NULL test.
3715///
3716/// Check if this free is accessed after its argument has been test
3717/// against NULL (property 0).
3718/// If yes, it is legal to move this call in its predecessor block.
3719///
3720/// The move is performed only if the block containing the call to free
3721/// will be removed, i.e.:
3722/// 1. it has only one predecessor P, and P has two successors
3723/// 2. it contains the call, noops, and an unconditional branch
3724/// 3. its successor is the same as its predecessor's successor
3725///
3726/// The profitability is out-of concern here and this function should
3727/// be called only if the caller knows this transformation would be
3728/// profitable (e.g., for code size).
3729static Instruction *tryToMoveFreeBeforeNullTest(CallInst &FI,
3730 const DataLayout &DL) {
3731 Value *Op = FI.getArgOperand(i: 0);
3732 BasicBlock *FreeInstrBB = FI.getParent();
3733 BasicBlock *PredBB = FreeInstrBB->getSinglePredecessor();
3734
3735 // Validate part of constraint #1: Only one predecessor
3736 // FIXME: We can extend the number of predecessor, but in that case, we
3737 // would duplicate the call to free in each predecessor and it may
3738 // not be profitable even for code size.
3739 if (!PredBB)
3740 return nullptr;
3741
3742 // Validate constraint #2: Does this block contains only the call to
3743 // free, noops, and an unconditional branch?
3744 BasicBlock *SuccBB;
3745 Instruction *FreeInstrBBTerminator = FreeInstrBB->getTerminator();
3746 if (!match(V: FreeInstrBBTerminator, P: m_UnconditionalBr(Succ&: SuccBB)))
3747 return nullptr;
3748
3749 // If there are only 2 instructions in the block, at this point,
3750 // this is the call to free and unconditional.
3751 // If there are more than 2 instructions, check that they are noops
3752 // i.e., they won't hurt the performance of the generated code.
3753 if (FreeInstrBB->size() != 2) {
3754 for (const Instruction &Inst : FreeInstrBB->instructionsWithoutDebug()) {
3755 if (&Inst == &FI || &Inst == FreeInstrBBTerminator)
3756 continue;
3757 auto *Cast = dyn_cast<CastInst>(Val: &Inst);
3758 if (!Cast || !Cast->isNoopCast(DL))
3759 return nullptr;
3760 }
3761 }
3762 // Validate the rest of constraint #1 by matching on the pred branch.
3763 Instruction *TI = PredBB->getTerminator();
3764 BasicBlock *TrueBB, *FalseBB;
3765 CmpPredicate Pred;
3766 if (!match(V: TI, P: m_Br(C: m_ICmp(Pred,
3767 L: m_CombineOr(L: m_Specific(V: Op),
3768 R: m_Specific(V: Op->stripPointerCasts())),
3769 R: m_Zero()),
3770 T&: TrueBB, F&: FalseBB)))
3771 return nullptr;
3772 if (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE)
3773 return nullptr;
3774
3775 // Validate constraint #3: Ensure the null case just falls through.
3776 if (SuccBB != (Pred == ICmpInst::ICMP_EQ ? TrueBB : FalseBB))
3777 return nullptr;
3778 assert(FreeInstrBB == (Pred == ICmpInst::ICMP_EQ ? FalseBB : TrueBB) &&
3779 "Broken CFG: missing edge from predecessor to successor");
3780
3781 // At this point, we know that everything in FreeInstrBB can be moved
3782 // before TI.
3783 for (Instruction &Instr : llvm::make_early_inc_range(Range&: *FreeInstrBB)) {
3784 if (&Instr == FreeInstrBBTerminator)
3785 break;
3786 Instr.moveBeforePreserving(MovePos: TI->getIterator());
3787 }
3788 assert(FreeInstrBB->size() == 1 &&
3789 "Only the branch instruction should remain");
3790
3791 // Now that we've moved the call to free before the NULL check, we have to
3792 // remove any attributes on its parameter that imply it's non-null, because
3793 // those attributes might have only been valid because of the NULL check, and
3794 // we can get miscompiles if we keep them. This is conservative if non-null is
3795 // also implied by something other than the NULL check, but it's guaranteed to
3796 // be correct, and the conservativeness won't matter in practice, since the
3797 // attributes are irrelevant for the call to free itself and the pointer
3798 // shouldn't be used after the call.
3799 AttributeList Attrs = FI.getAttributes();
3800 Attrs = Attrs.removeParamAttribute(C&: FI.getContext(), ArgNo: 0, Kind: Attribute::NonNull);
3801 Attribute Dereferenceable = Attrs.getParamAttr(ArgNo: 0, Kind: Attribute::Dereferenceable);
3802 if (Dereferenceable.isValid()) {
3803 uint64_t Bytes = Dereferenceable.getDereferenceableBytes();
3804 Attrs = Attrs.removeParamAttribute(C&: FI.getContext(), ArgNo: 0,
3805 Kind: Attribute::Dereferenceable);
3806 Attrs = Attrs.addDereferenceableOrNullParamAttr(C&: FI.getContext(), ArgNo: 0, Bytes);
3807 }
3808 FI.setAttributes(Attrs);
3809
3810 return &FI;
3811}
3812
3813Instruction *InstCombinerImpl::visitFree(CallInst &FI, Value *Op) {
3814 // free undef -> unreachable.
3815 if (isa<UndefValue>(Val: Op)) {
3816 // Leave a marker since we can't modify the CFG here.
3817 CreateNonTerminatorUnreachable(InsertAt: &FI);
3818 return eraseInstFromFunction(I&: FI);
3819 }
3820
3821 // If we have 'free null' delete the instruction. This can happen in stl code
3822 // when lots of inlining happens.
3823 if (isa<ConstantPointerNull>(Val: Op))
3824 return eraseInstFromFunction(I&: FI);
3825
3826 // If we had free(realloc(...)) with no intervening uses, then eliminate the
3827 // realloc() entirely.
3828 CallInst *CI = dyn_cast<CallInst>(Val: Op);
3829 if (CI && CI->hasOneUse())
3830 if (Value *ReallocatedOp = getReallocatedOperand(CB: CI))
3831 return eraseInstFromFunction(I&: *replaceInstUsesWith(I&: *CI, V: ReallocatedOp));
3832
3833 // If we optimize for code size, try to move the call to free before the null
3834 // test so that simplify cfg can remove the empty block and dead code
3835 // elimination the branch. I.e., helps to turn something like:
3836 // if (foo) free(foo);
3837 // into
3838 // free(foo);
3839 //
3840 // Note that we can only do this for 'free' and not for any flavor of
3841 // 'operator delete'; there is no 'operator delete' symbol for which we are
3842 // permitted to invent a call, even if we're passing in a null pointer.
3843 if (MinimizeSize) {
3844 LibFunc Func;
3845 if (TLI.getLibFunc(CB: FI, F&: Func) && TLI.has(F: Func) && Func == LibFunc_free)
3846 if (Instruction *I = tryToMoveFreeBeforeNullTest(FI, DL))
3847 return I;
3848 }
3849
3850 return nullptr;
3851}
3852
3853Instruction *InstCombinerImpl::visitReturnInst(ReturnInst &RI) {
3854 Value *RetVal = RI.getReturnValue();
3855 if (!RetVal)
3856 return nullptr;
3857
3858 Function *F = RI.getFunction();
3859 Type *RetTy = RetVal->getType();
3860 if (RetTy->isPointerTy()) {
3861 bool HasDereferenceable =
3862 F->getAttributes().getRetDereferenceableBytes() > 0;
3863 if (F->hasRetAttribute(Kind: Attribute::NonNull) ||
3864 (HasDereferenceable &&
3865 !NullPointerIsDefined(F, AS: RetTy->getPointerAddressSpace()))) {
3866 if (Value *V = simplifyNonNullOperand(V: RetVal, HasDereferenceable))
3867 return replaceOperand(I&: RI, OpNum: 0, V);
3868 }
3869 }
3870
3871 if (!AttributeFuncs::isNoFPClassCompatibleType(Ty: RetTy))
3872 return nullptr;
3873
3874 FPClassTest ReturnClass = F->getAttributes().getRetNoFPClass();
3875 if (ReturnClass == fcNone)
3876 return nullptr;
3877
3878 KnownFPClass KnownClass;
3879 Value *Simplified =
3880 SimplifyDemandedUseFPClass(V: RetVal, DemandedMask: ~ReturnClass, Known&: KnownClass, CxtI: &RI);
3881 if (!Simplified)
3882 return nullptr;
3883
3884 return ReturnInst::Create(C&: RI.getContext(), retVal: Simplified);
3885}
3886
3887// WARNING: keep in sync with SimplifyCFGOpt::simplifyUnreachable()!
3888bool InstCombinerImpl::removeInstructionsBeforeUnreachable(Instruction &I) {
3889 // Try to remove the previous instruction if it must lead to unreachable.
3890 // This includes instructions like stores and "llvm.assume" that may not get
3891 // removed by simple dead code elimination.
3892 bool Changed = false;
3893 while (Instruction *Prev = I.getPrevNonDebugInstruction()) {
3894 // While we theoretically can erase EH, that would result in a block that
3895 // used to start with an EH no longer starting with EH, which is invalid.
3896 // To make it valid, we'd need to fixup predecessors to no longer refer to
3897 // this block, but that changes CFG, which is not allowed in InstCombine.
3898 if (Prev->isEHPad())
3899 break; // Can not drop any more instructions. We're done here.
3900
3901 if (!isGuaranteedToTransferExecutionToSuccessor(I: Prev))
3902 break; // Can not drop any more instructions. We're done here.
3903 // Otherwise, this instruction can be freely erased,
3904 // even if it is not side-effect free.
3905
3906 // A value may still have uses before we process it here (for example, in
3907 // another unreachable block), so convert those to poison.
3908 replaceInstUsesWith(I&: *Prev, V: PoisonValue::get(T: Prev->getType()));
3909 eraseInstFromFunction(I&: *Prev);
3910 Changed = true;
3911 }
3912 return Changed;
3913}
3914
3915Instruction *InstCombinerImpl::visitUnreachableInst(UnreachableInst &I) {
3916 removeInstructionsBeforeUnreachable(I);
3917 return nullptr;
3918}
3919
3920Instruction *InstCombinerImpl::visitUnconditionalBranchInst(BranchInst &BI) {
3921 assert(BI.isUnconditional() && "Only for unconditional branches.");
3922
3923 // If this store is the second-to-last instruction in the basic block
3924 // (excluding debug info) and if the block ends with
3925 // an unconditional branch, try to move the store to the successor block.
3926
3927 auto GetLastSinkableStore = [](BasicBlock::iterator BBI) {
3928 BasicBlock::iterator FirstInstr = BBI->getParent()->begin();
3929 do {
3930 if (BBI != FirstInstr)
3931 --BBI;
3932 } while (BBI != FirstInstr && BBI->isDebugOrPseudoInst());
3933
3934 return dyn_cast<StoreInst>(Val&: BBI);
3935 };
3936
3937 if (StoreInst *SI = GetLastSinkableStore(BasicBlock::iterator(BI)))
3938 if (mergeStoreIntoSuccessor(SI&: *SI))
3939 return &BI;
3940
3941 return nullptr;
3942}
3943
3944void InstCombinerImpl::addDeadEdge(BasicBlock *From, BasicBlock *To,
3945 SmallVectorImpl<BasicBlock *> &Worklist) {
3946 if (!DeadEdges.insert(V: {From, To}).second)
3947 return;
3948
3949 // Replace phi node operands in successor with poison.
3950 for (PHINode &PN : To->phis())
3951 for (Use &U : PN.incoming_values())
3952 if (PN.getIncomingBlock(U) == From && !isa<PoisonValue>(Val: U)) {
3953 replaceUse(U, NewValue: PoisonValue::get(T: PN.getType()));
3954 addToWorklist(I: &PN);
3955 MadeIRChange = true;
3956 }
3957
3958 Worklist.push_back(Elt: To);
3959}
3960
3961// Under the assumption that I is unreachable, remove it and following
3962// instructions. Changes are reported directly to MadeIRChange.
3963void InstCombinerImpl::handleUnreachableFrom(
3964 Instruction *I, SmallVectorImpl<BasicBlock *> &Worklist) {
3965 BasicBlock *BB = I->getParent();
3966 for (Instruction &Inst : make_early_inc_range(
3967 Range: make_range(x: std::next(x: BB->getTerminator()->getReverseIterator()),
3968 y: std::next(x: I->getReverseIterator())))) {
3969 if (!Inst.use_empty() && !Inst.getType()->isTokenTy()) {
3970 replaceInstUsesWith(I&: Inst, V: PoisonValue::get(T: Inst.getType()));
3971 MadeIRChange = true;
3972 }
3973 if (Inst.isEHPad() || Inst.getType()->isTokenTy())
3974 continue;
3975 // RemoveDIs: erase debug-info on this instruction manually.
3976 Inst.dropDbgRecords();
3977 eraseInstFromFunction(I&: Inst);
3978 MadeIRChange = true;
3979 }
3980
3981 SmallVector<Value *> Changed;
3982 if (handleUnreachableTerminator(I: BB->getTerminator(), PoisonedValues&: Changed)) {
3983 MadeIRChange = true;
3984 for (Value *V : Changed)
3985 addToWorklist(I: cast<Instruction>(Val: V));
3986 }
3987
3988 // Handle potentially dead successors.
3989 for (BasicBlock *Succ : successors(BB))
3990 addDeadEdge(From: BB, To: Succ, Worklist);
3991}
3992
3993void InstCombinerImpl::handlePotentiallyDeadBlocks(
3994 SmallVectorImpl<BasicBlock *> &Worklist) {
3995 while (!Worklist.empty()) {
3996 BasicBlock *BB = Worklist.pop_back_val();
3997 if (!all_of(Range: predecessors(BB), P: [&](BasicBlock *Pred) {
3998 return DeadEdges.contains(V: {Pred, BB}) || DT.dominates(A: BB, B: Pred);
3999 }))
4000 continue;
4001
4002 handleUnreachableFrom(I: &BB->front(), Worklist);
4003 }
4004}
4005
4006void InstCombinerImpl::handlePotentiallyDeadSuccessors(BasicBlock *BB,
4007 BasicBlock *LiveSucc) {
4008 SmallVector<BasicBlock *> Worklist;
4009 for (BasicBlock *Succ : successors(BB)) {
4010 // The live successor isn't dead.
4011 if (Succ == LiveSucc)
4012 continue;
4013
4014 addDeadEdge(From: BB, To: Succ, Worklist);
4015 }
4016
4017 handlePotentiallyDeadBlocks(Worklist);
4018}
4019
4020Instruction *InstCombinerImpl::visitBranchInst(BranchInst &BI) {
4021 if (BI.isUnconditional())
4022 return visitUnconditionalBranchInst(BI);
4023
4024 // Change br (not X), label True, label False to: br X, label False, True
4025 Value *Cond = BI.getCondition();
4026 Value *X;
4027 if (match(V: Cond, P: m_Not(V: m_Value(V&: X))) && !isa<Constant>(Val: X)) {
4028 // Swap Destinations and condition...
4029 BI.swapSuccessors();
4030 if (BPI)
4031 BPI->swapSuccEdgesProbabilities(Src: BI.getParent());
4032 return replaceOperand(I&: BI, OpNum: 0, V: X);
4033 }
4034
4035 // Canonicalize logical-and-with-invert as logical-or-with-invert.
4036 // This is done by inverting the condition and swapping successors:
4037 // br (X && !Y), T, F --> br !(X && !Y), F, T --> br (!X || Y), F, T
4038 Value *Y;
4039 if (isa<SelectInst>(Val: Cond) &&
4040 match(V: Cond,
4041 P: m_OneUse(SubPattern: m_LogicalAnd(L: m_Value(V&: X), R: m_OneUse(SubPattern: m_Not(V: m_Value(V&: Y))))))) {
4042 Value *NotX = Builder.CreateNot(V: X, Name: "not." + X->getName());
4043 Value *Or = Builder.CreateLogicalOr(Cond1: NotX, Cond2: Y);
4044 BI.swapSuccessors();
4045 if (BPI)
4046 BPI->swapSuccEdgesProbabilities(Src: BI.getParent());
4047 return replaceOperand(I&: BI, OpNum: 0, V: Or);
4048 }
4049
4050 // If the condition is irrelevant, remove the use so that other
4051 // transforms on the condition become more effective.
4052 if (!isa<ConstantInt>(Val: Cond) && BI.getSuccessor(i: 0) == BI.getSuccessor(i: 1))
4053 return replaceOperand(I&: BI, OpNum: 0, V: ConstantInt::getFalse(Ty: Cond->getType()));
4054
4055 // Canonicalize, for example, fcmp_one -> fcmp_oeq.
4056 CmpPredicate Pred;
4057 if (match(V: Cond, P: m_OneUse(SubPattern: m_FCmp(Pred, L: m_Value(), R: m_Value()))) &&
4058 !isCanonicalPredicate(Pred)) {
4059 // Swap destinations and condition.
4060 auto *Cmp = cast<CmpInst>(Val: Cond);
4061 Cmp->setPredicate(CmpInst::getInversePredicate(pred: Pred));
4062 BI.swapSuccessors();
4063 if (BPI)
4064 BPI->swapSuccEdgesProbabilities(Src: BI.getParent());
4065 Worklist.push(I: Cmp);
4066 return &BI;
4067 }
4068
4069 if (isa<UndefValue>(Val: Cond)) {
4070 handlePotentiallyDeadSuccessors(BB: BI.getParent(), /*LiveSucc*/ nullptr);
4071 return nullptr;
4072 }
4073 if (auto *CI = dyn_cast<ConstantInt>(Val: Cond)) {
4074 handlePotentiallyDeadSuccessors(BB: BI.getParent(),
4075 LiveSucc: BI.getSuccessor(i: !CI->getZExtValue()));
4076 return nullptr;
4077 }
4078
4079 // Replace all dominated uses of the condition with true/false
4080 // Ignore constant expressions to avoid iterating over uses on other
4081 // functions.
4082 if (!isa<Constant>(Val: Cond) && BI.getSuccessor(i: 0) != BI.getSuccessor(i: 1)) {
4083 for (auto &U : make_early_inc_range(Range: Cond->uses())) {
4084 BasicBlockEdge Edge0(BI.getParent(), BI.getSuccessor(i: 0));
4085 if (DT.dominates(BBE: Edge0, U)) {
4086 replaceUse(U, NewValue: ConstantInt::getTrue(Ty: Cond->getType()));
4087 addToWorklist(I: cast<Instruction>(Val: U.getUser()));
4088 continue;
4089 }
4090 BasicBlockEdge Edge1(BI.getParent(), BI.getSuccessor(i: 1));
4091 if (DT.dominates(BBE: Edge1, U)) {
4092 replaceUse(U, NewValue: ConstantInt::getFalse(Ty: Cond->getType()));
4093 addToWorklist(I: cast<Instruction>(Val: U.getUser()));
4094 }
4095 }
4096 }
4097
4098 DC.registerBranch(BI: &BI);
4099 return nullptr;
4100}
4101
4102// Replaces (switch (select cond, X, C)/(select cond, C, X)) with (switch X) if
4103// we can prove that both (switch C) and (switch X) go to the default when cond
4104// is false/true.
4105static Value *simplifySwitchOnSelectUsingRanges(SwitchInst &SI,
4106 SelectInst *Select,
4107 bool IsTrueArm) {
4108 unsigned CstOpIdx = IsTrueArm ? 1 : 2;
4109 auto *C = dyn_cast<ConstantInt>(Val: Select->getOperand(i_nocapture: CstOpIdx));
4110 if (!C)
4111 return nullptr;
4112
4113 BasicBlock *CstBB = SI.findCaseValue(C)->getCaseSuccessor();
4114 if (CstBB != SI.getDefaultDest())
4115 return nullptr;
4116 Value *X = Select->getOperand(i_nocapture: 3 - CstOpIdx);
4117 CmpPredicate Pred;
4118 const APInt *RHSC;
4119 if (!match(V: Select->getCondition(),
4120 P: m_ICmp(Pred, L: m_Specific(V: X), R: m_APInt(Res&: RHSC))))
4121 return nullptr;
4122 if (IsTrueArm)
4123 Pred = ICmpInst::getInversePredicate(pred: Pred);
4124
4125 // See whether we can replace the select with X
4126 ConstantRange CR = ConstantRange::makeExactICmpRegion(Pred, Other: *RHSC);
4127 for (auto Case : SI.cases())
4128 if (!CR.contains(Val: Case.getCaseValue()->getValue()))
4129 return nullptr;
4130
4131 return X;
4132}
4133
4134Instruction *InstCombinerImpl::visitSwitchInst(SwitchInst &SI) {
4135 Value *Cond = SI.getCondition();
4136 Value *Op0;
4137 ConstantInt *AddRHS;
4138 if (match(V: Cond, P: m_Add(L: m_Value(V&: Op0), R: m_ConstantInt(CI&: AddRHS)))) {
4139 // Change 'switch (X+4) case 1:' into 'switch (X) case -3'.
4140 for (auto Case : SI.cases()) {
4141 Constant *NewCase = ConstantExpr::getSub(C1: Case.getCaseValue(), C2: AddRHS);
4142 assert(isa<ConstantInt>(NewCase) &&
4143 "Result of expression should be constant");
4144 Case.setValue(cast<ConstantInt>(Val: NewCase));
4145 }
4146 return replaceOperand(I&: SI, OpNum: 0, V: Op0);
4147 }
4148
4149 ConstantInt *SubLHS;
4150 if (match(V: Cond, P: m_Sub(L: m_ConstantInt(CI&: SubLHS), R: m_Value(V&: Op0)))) {
4151 // Change 'switch (1-X) case 1:' into 'switch (X) case 0'.
4152 for (auto Case : SI.cases()) {
4153 Constant *NewCase = ConstantExpr::getSub(C1: SubLHS, C2: Case.getCaseValue());
4154 assert(isa<ConstantInt>(NewCase) &&
4155 "Result of expression should be constant");
4156 Case.setValue(cast<ConstantInt>(Val: NewCase));
4157 }
4158 return replaceOperand(I&: SI, OpNum: 0, V: Op0);
4159 }
4160
4161 uint64_t ShiftAmt;
4162 if (match(V: Cond, P: m_Shl(L: m_Value(V&: Op0), R: m_ConstantInt(V&: ShiftAmt))) &&
4163 ShiftAmt < Op0->getType()->getScalarSizeInBits() &&
4164 all_of(Range: SI.cases(), P: [&](const auto &Case) {
4165 return Case.getCaseValue()->getValue().countr_zero() >= ShiftAmt;
4166 })) {
4167 // Change 'switch (X << 2) case 4:' into 'switch (X) case 1:'.
4168 OverflowingBinaryOperator *Shl = cast<OverflowingBinaryOperator>(Val: Cond);
4169 if (Shl->hasNoUnsignedWrap() || Shl->hasNoSignedWrap() ||
4170 Shl->hasOneUse()) {
4171 Value *NewCond = Op0;
4172 if (!Shl->hasNoUnsignedWrap() && !Shl->hasNoSignedWrap()) {
4173 // If the shift may wrap, we need to mask off the shifted bits.
4174 unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
4175 NewCond = Builder.CreateAnd(
4176 LHS: Op0, RHS: APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - ShiftAmt));
4177 }
4178 for (auto Case : SI.cases()) {
4179 const APInt &CaseVal = Case.getCaseValue()->getValue();
4180 APInt ShiftedCase = Shl->hasNoSignedWrap() ? CaseVal.ashr(ShiftAmt)
4181 : CaseVal.lshr(shiftAmt: ShiftAmt);
4182 Case.setValue(ConstantInt::get(Context&: SI.getContext(), V: ShiftedCase));
4183 }
4184 return replaceOperand(I&: SI, OpNum: 0, V: NewCond);
4185 }
4186 }
4187
4188 // Fold switch(zext/sext(X)) into switch(X) if possible.
4189 if (match(V: Cond, P: m_ZExtOrSExt(Op: m_Value(V&: Op0)))) {
4190 bool IsZExt = isa<ZExtInst>(Val: Cond);
4191 Type *SrcTy = Op0->getType();
4192 unsigned NewWidth = SrcTy->getScalarSizeInBits();
4193
4194 if (all_of(Range: SI.cases(), P: [&](const auto &Case) {
4195 const APInt &CaseVal = Case.getCaseValue()->getValue();
4196 return IsZExt ? CaseVal.isIntN(N: NewWidth)
4197 : CaseVal.isSignedIntN(N: NewWidth);
4198 })) {
4199 for (auto &Case : SI.cases()) {
4200 APInt TruncatedCase = Case.getCaseValue()->getValue().trunc(width: NewWidth);
4201 Case.setValue(ConstantInt::get(Context&: SI.getContext(), V: TruncatedCase));
4202 }
4203 return replaceOperand(I&: SI, OpNum: 0, V: Op0);
4204 }
4205 }
4206
4207 // Fold switch(select cond, X, Y) into switch(X/Y) if possible
4208 if (auto *Select = dyn_cast<SelectInst>(Val: Cond)) {
4209 if (Value *V =
4210 simplifySwitchOnSelectUsingRanges(SI, Select, /*IsTrueArm=*/true))
4211 return replaceOperand(I&: SI, OpNum: 0, V);
4212 if (Value *V =
4213 simplifySwitchOnSelectUsingRanges(SI, Select, /*IsTrueArm=*/false))
4214 return replaceOperand(I&: SI, OpNum: 0, V);
4215 }
4216
4217 KnownBits Known = computeKnownBits(V: Cond, CxtI: &SI);
4218 unsigned LeadingKnownZeros = Known.countMinLeadingZeros();
4219 unsigned LeadingKnownOnes = Known.countMinLeadingOnes();
4220
4221 // Compute the number of leading bits we can ignore.
4222 // TODO: A better way to determine this would use ComputeNumSignBits().
4223 for (const auto &C : SI.cases()) {
4224 LeadingKnownZeros =
4225 std::min(a: LeadingKnownZeros, b: C.getCaseValue()->getValue().countl_zero());
4226 LeadingKnownOnes =
4227 std::min(a: LeadingKnownOnes, b: C.getCaseValue()->getValue().countl_one());
4228 }
4229
4230 unsigned NewWidth = Known.getBitWidth() - std::max(a: LeadingKnownZeros, b: LeadingKnownOnes);
4231
4232 // Shrink the condition operand if the new type is smaller than the old type.
4233 // But do not shrink to a non-standard type, because backend can't generate
4234 // good code for that yet.
4235 // TODO: We can make it aggressive again after fixing PR39569.
4236 if (NewWidth > 0 && NewWidth < Known.getBitWidth() &&
4237 shouldChangeType(FromWidth: Known.getBitWidth(), ToWidth: NewWidth)) {
4238 IntegerType *Ty = IntegerType::get(C&: SI.getContext(), NumBits: NewWidth);
4239 Builder.SetInsertPoint(&SI);
4240 Value *NewCond = Builder.CreateTrunc(V: Cond, DestTy: Ty, Name: "trunc");
4241
4242 for (auto Case : SI.cases()) {
4243 APInt TruncatedCase = Case.getCaseValue()->getValue().trunc(width: NewWidth);
4244 Case.setValue(ConstantInt::get(Context&: SI.getContext(), V: TruncatedCase));
4245 }
4246 return replaceOperand(I&: SI, OpNum: 0, V: NewCond);
4247 }
4248
4249 if (isa<UndefValue>(Val: Cond)) {
4250 handlePotentiallyDeadSuccessors(BB: SI.getParent(), /*LiveSucc*/ nullptr);
4251 return nullptr;
4252 }
4253 if (auto *CI = dyn_cast<ConstantInt>(Val: Cond)) {
4254 handlePotentiallyDeadSuccessors(BB: SI.getParent(),
4255 LiveSucc: SI.findCaseValue(C: CI)->getCaseSuccessor());
4256 return nullptr;
4257 }
4258
4259 return nullptr;
4260}
4261
4262Instruction *
4263InstCombinerImpl::foldExtractOfOverflowIntrinsic(ExtractValueInst &EV) {
4264 auto *WO = dyn_cast<WithOverflowInst>(Val: EV.getAggregateOperand());
4265 if (!WO)
4266 return nullptr;
4267
4268 Intrinsic::ID OvID = WO->getIntrinsicID();
4269 const APInt *C = nullptr;
4270 if (match(V: WO->getRHS(), P: m_APIntAllowPoison(Res&: C))) {
4271 if (*EV.idx_begin() == 0 && (OvID == Intrinsic::smul_with_overflow ||
4272 OvID == Intrinsic::umul_with_overflow)) {
4273 // extractvalue (any_mul_with_overflow X, -1), 0 --> -X
4274 if (C->isAllOnes())
4275 return BinaryOperator::CreateNeg(Op: WO->getLHS());
4276 // extractvalue (any_mul_with_overflow X, 2^n), 0 --> X << n
4277 if (C->isPowerOf2()) {
4278 return BinaryOperator::CreateShl(
4279 V1: WO->getLHS(),
4280 V2: ConstantInt::get(Ty: WO->getLHS()->getType(), V: C->logBase2()));
4281 }
4282 }
4283 }
4284
4285 // We're extracting from an overflow intrinsic. See if we're the only user.
4286 // That allows us to simplify multiple result intrinsics to simpler things
4287 // that just get one value.
4288 if (!WO->hasOneUse())
4289 return nullptr;
4290
4291 // Check if we're grabbing only the result of a 'with overflow' intrinsic
4292 // and replace it with a traditional binary instruction.
4293 if (*EV.idx_begin() == 0) {
4294 Instruction::BinaryOps BinOp = WO->getBinaryOp();
4295 Value *LHS = WO->getLHS(), *RHS = WO->getRHS();
4296 // Replace the old instruction's uses with poison.
4297 replaceInstUsesWith(I&: *WO, V: PoisonValue::get(T: WO->getType()));
4298 eraseInstFromFunction(I&: *WO);
4299 return BinaryOperator::Create(Op: BinOp, S1: LHS, S2: RHS);
4300 }
4301
4302 assert(*EV.idx_begin() == 1 && "Unexpected extract index for overflow inst");
4303
4304 // (usub LHS, RHS) overflows when LHS is unsigned-less-than RHS.
4305 if (OvID == Intrinsic::usub_with_overflow)
4306 return new ICmpInst(ICmpInst::ICMP_ULT, WO->getLHS(), WO->getRHS());
4307
4308 // smul with i1 types overflows when both sides are set: -1 * -1 == +1, but
4309 // +1 is not possible because we assume signed values.
4310 if (OvID == Intrinsic::smul_with_overflow &&
4311 WO->getLHS()->getType()->isIntOrIntVectorTy(BitWidth: 1))
4312 return BinaryOperator::CreateAnd(V1: WO->getLHS(), V2: WO->getRHS());
4313
4314 // extractvalue (umul_with_overflow X, X), 1 -> X u> 2^(N/2)-1
4315 if (OvID == Intrinsic::umul_with_overflow && WO->getLHS() == WO->getRHS()) {
4316 unsigned BitWidth = WO->getLHS()->getType()->getScalarSizeInBits();
4317 // Only handle even bitwidths for performance reasons.
4318 if (BitWidth % 2 == 0)
4319 return new ICmpInst(
4320 ICmpInst::ICMP_UGT, WO->getLHS(),
4321 ConstantInt::get(Ty: WO->getLHS()->getType(),
4322 V: APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth / 2)));
4323 }
4324
4325 // If only the overflow result is used, and the right hand side is a
4326 // constant (or constant splat), we can remove the intrinsic by directly
4327 // checking for overflow.
4328 if (C) {
4329 // Compute the no-wrap range for LHS given RHS=C, then construct an
4330 // equivalent icmp, potentially using an offset.
4331 ConstantRange NWR = ConstantRange::makeExactNoWrapRegion(
4332 BinOp: WO->getBinaryOp(), Other: *C, NoWrapKind: WO->getNoWrapKind());
4333
4334 CmpInst::Predicate Pred;
4335 APInt NewRHSC, Offset;
4336 NWR.getEquivalentICmp(Pred, RHS&: NewRHSC, Offset);
4337 auto *OpTy = WO->getRHS()->getType();
4338 auto *NewLHS = WO->getLHS();
4339 if (Offset != 0)
4340 NewLHS = Builder.CreateAdd(LHS: NewLHS, RHS: ConstantInt::get(Ty: OpTy, V: Offset));
4341 return new ICmpInst(ICmpInst::getInversePredicate(pred: Pred), NewLHS,
4342 ConstantInt::get(Ty: OpTy, V: NewRHSC));
4343 }
4344
4345 return nullptr;
4346}
4347
4348static Value *foldFrexpOfSelect(ExtractValueInst &EV, IntrinsicInst *FrexpCall,
4349 SelectInst *SelectInst,
4350 InstCombiner::BuilderTy &Builder) {
4351 // Helper to fold frexp of select to select of frexp.
4352
4353 if (!SelectInst->hasOneUse() || !FrexpCall->hasOneUse())
4354 return nullptr;
4355 Value *Cond = SelectInst->getCondition();
4356 Value *TrueVal = SelectInst->getTrueValue();
4357 Value *FalseVal = SelectInst->getFalseValue();
4358
4359 const APFloat *ConstVal = nullptr;
4360 Value *VarOp = nullptr;
4361 bool ConstIsTrue = false;
4362
4363 if (match(V: TrueVal, P: m_APFloat(Res&: ConstVal))) {
4364 VarOp = FalseVal;
4365 ConstIsTrue = true;
4366 } else if (match(V: FalseVal, P: m_APFloat(Res&: ConstVal))) {
4367 VarOp = TrueVal;
4368 ConstIsTrue = false;
4369 } else {
4370 return nullptr;
4371 }
4372
4373 Builder.SetInsertPoint(&EV);
4374
4375 CallInst *NewFrexp =
4376 Builder.CreateCall(Callee: FrexpCall->getCalledFunction(), Args: {VarOp}, Name: "frexp");
4377 NewFrexp->copyIRFlags(V: FrexpCall);
4378
4379 Value *NewEV = Builder.CreateExtractValue(Agg: NewFrexp, Idxs: 0, Name: "mantissa");
4380
4381 int Exp;
4382 APFloat Mantissa = frexp(X: *ConstVal, Exp, RM: APFloat::rmNearestTiesToEven);
4383
4384 Constant *ConstantMantissa = ConstantFP::get(Ty: TrueVal->getType(), V: Mantissa);
4385
4386 Value *NewSel = Builder.CreateSelectFMF(
4387 C: Cond, True: ConstIsTrue ? ConstantMantissa : NewEV,
4388 False: ConstIsTrue ? NewEV : ConstantMantissa, FMFSource: SelectInst, Name: "select.frexp");
4389 return NewSel;
4390}
4391Instruction *InstCombinerImpl::visitExtractValueInst(ExtractValueInst &EV) {
4392 Value *Agg = EV.getAggregateOperand();
4393
4394 if (!EV.hasIndices())
4395 return replaceInstUsesWith(I&: EV, V: Agg);
4396
4397 if (Value *V = simplifyExtractValueInst(Agg, Idxs: EV.getIndices(),
4398 Q: SQ.getWithInstruction(I: &EV)))
4399 return replaceInstUsesWith(I&: EV, V);
4400
4401 Value *Cond, *TrueVal, *FalseVal;
4402 if (match(V: &EV, P: m_ExtractValue<0>(V: m_Intrinsic<Intrinsic::frexp>(Op0: m_Select(
4403 C: m_Value(V&: Cond), L: m_Value(V&: TrueVal), R: m_Value(V&: FalseVal)))))) {
4404 auto *SelInst =
4405 cast<SelectInst>(Val: cast<IntrinsicInst>(Val: Agg)->getArgOperand(i: 0));
4406 if (Value *Result =
4407 foldFrexpOfSelect(EV, FrexpCall: cast<IntrinsicInst>(Val: Agg), SelectInst: SelInst, Builder))
4408 return replaceInstUsesWith(I&: EV, V: Result);
4409 }
4410 if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Val: Agg)) {
4411 // We're extracting from an insertvalue instruction, compare the indices
4412 const unsigned *exti, *exte, *insi, *inse;
4413 for (exti = EV.idx_begin(), insi = IV->idx_begin(),
4414 exte = EV.idx_end(), inse = IV->idx_end();
4415 exti != exte && insi != inse;
4416 ++exti, ++insi) {
4417 if (*insi != *exti)
4418 // The insert and extract both reference distinctly different elements.
4419 // This means the extract is not influenced by the insert, and we can
4420 // replace the aggregate operand of the extract with the aggregate
4421 // operand of the insert. i.e., replace
4422 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
4423 // %E = extractvalue { i32, { i32 } } %I, 0
4424 // with
4425 // %E = extractvalue { i32, { i32 } } %A, 0
4426 return ExtractValueInst::Create(Agg: IV->getAggregateOperand(),
4427 Idxs: EV.getIndices());
4428 }
4429 if (exti == exte && insi == inse)
4430 // Both iterators are at the end: Index lists are identical. Replace
4431 // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
4432 // %C = extractvalue { i32, { i32 } } %B, 1, 0
4433 // with "i32 42"
4434 return replaceInstUsesWith(I&: EV, V: IV->getInsertedValueOperand());
4435 if (exti == exte) {
4436 // The extract list is a prefix of the insert list. i.e. replace
4437 // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
4438 // %E = extractvalue { i32, { i32 } } %I, 1
4439 // with
4440 // %X = extractvalue { i32, { i32 } } %A, 1
4441 // %E = insertvalue { i32 } %X, i32 42, 0
4442 // by switching the order of the insert and extract (though the
4443 // insertvalue should be left in, since it may have other uses).
4444 Value *NewEV = Builder.CreateExtractValue(Agg: IV->getAggregateOperand(),
4445 Idxs: EV.getIndices());
4446 return InsertValueInst::Create(Agg: NewEV, Val: IV->getInsertedValueOperand(),
4447 Idxs: ArrayRef(insi, inse));
4448 }
4449 if (insi == inse)
4450 // The insert list is a prefix of the extract list
4451 // We can simply remove the common indices from the extract and make it
4452 // operate on the inserted value instead of the insertvalue result.
4453 // i.e., replace
4454 // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
4455 // %E = extractvalue { i32, { i32 } } %I, 1, 0
4456 // with
4457 // %E extractvalue { i32 } { i32 42 }, 0
4458 return ExtractValueInst::Create(Agg: IV->getInsertedValueOperand(),
4459 Idxs: ArrayRef(exti, exte));
4460 }
4461
4462 if (Instruction *R = foldExtractOfOverflowIntrinsic(EV))
4463 return R;
4464
4465 if (LoadInst *L = dyn_cast<LoadInst>(Val: Agg)) {
4466 // Bail out if the aggregate contains scalable vector type
4467 if (auto *STy = dyn_cast<StructType>(Val: Agg->getType());
4468 STy && STy->isScalableTy())
4469 return nullptr;
4470
4471 // If the (non-volatile) load only has one use, we can rewrite this to a
4472 // load from a GEP. This reduces the size of the load. If a load is used
4473 // only by extractvalue instructions then this either must have been
4474 // optimized before, or it is a struct with padding, in which case we
4475 // don't want to do the transformation as it loses padding knowledge.
4476 if (L->isSimple() && L->hasOneUse()) {
4477 // extractvalue has integer indices, getelementptr has Value*s. Convert.
4478 SmallVector<Value*, 4> Indices;
4479 // Prefix an i32 0 since we need the first element.
4480 Indices.push_back(Elt: Builder.getInt32(C: 0));
4481 for (unsigned Idx : EV.indices())
4482 Indices.push_back(Elt: Builder.getInt32(C: Idx));
4483
4484 // We need to insert these at the location of the old load, not at that of
4485 // the extractvalue.
4486 Builder.SetInsertPoint(L);
4487 Value *GEP = Builder.CreateInBoundsGEP(Ty: L->getType(),
4488 Ptr: L->getPointerOperand(), IdxList: Indices);
4489 Instruction *NL = Builder.CreateLoad(Ty: EV.getType(), Ptr: GEP);
4490 // Whatever aliasing information we had for the orignal load must also
4491 // hold for the smaller load, so propagate the annotations.
4492 NL->setAAMetadata(L->getAAMetadata());
4493 // Returning the load directly will cause the main loop to insert it in
4494 // the wrong spot, so use replaceInstUsesWith().
4495 return replaceInstUsesWith(I&: EV, V: NL);
4496 }
4497 }
4498
4499 if (auto *PN = dyn_cast<PHINode>(Val: Agg))
4500 if (Instruction *Res = foldOpIntoPhi(I&: EV, PN))
4501 return Res;
4502
4503 // Canonicalize extract (select Cond, TV, FV)
4504 // -> select cond, (extract TV), (extract FV)
4505 if (auto *SI = dyn_cast<SelectInst>(Val: Agg))
4506 if (Instruction *R = FoldOpIntoSelect(Op&: EV, SI, /*FoldWithMultiUse=*/true))
4507 return R;
4508
4509 // We could simplify extracts from other values. Note that nested extracts may
4510 // already be simplified implicitly by the above: extract (extract (insert) )
4511 // will be translated into extract ( insert ( extract ) ) first and then just
4512 // the value inserted, if appropriate. Similarly for extracts from single-use
4513 // loads: extract (extract (load)) will be translated to extract (load (gep))
4514 // and if again single-use then via load (gep (gep)) to load (gep).
4515 // However, double extracts from e.g. function arguments or return values
4516 // aren't handled yet.
4517 return nullptr;
4518}
4519
4520/// Return 'true' if the given typeinfo will match anything.
4521static bool isCatchAll(EHPersonality Personality, Constant *TypeInfo) {
4522 switch (Personality) {
4523 case EHPersonality::GNU_C:
4524 case EHPersonality::GNU_C_SjLj:
4525 case EHPersonality::Rust:
4526 // The GCC C EH and Rust personality only exists to support cleanups, so
4527 // it's not clear what the semantics of catch clauses are.
4528 return false;
4529 case EHPersonality::Unknown:
4530 return false;
4531 case EHPersonality::GNU_Ada:
4532 // While __gnat_all_others_value will match any Ada exception, it doesn't
4533 // match foreign exceptions (or didn't, before gcc-4.7).
4534 return false;
4535 case EHPersonality::GNU_CXX:
4536 case EHPersonality::GNU_CXX_SjLj:
4537 case EHPersonality::GNU_ObjC:
4538 case EHPersonality::MSVC_X86SEH:
4539 case EHPersonality::MSVC_TableSEH:
4540 case EHPersonality::MSVC_CXX:
4541 case EHPersonality::CoreCLR:
4542 case EHPersonality::Wasm_CXX:
4543 case EHPersonality::XL_CXX:
4544 case EHPersonality::ZOS_CXX:
4545 return TypeInfo->isNullValue();
4546 }
4547 llvm_unreachable("invalid enum");
4548}
4549
4550static bool shorter_filter(const Value *LHS, const Value *RHS) {
4551 return
4552 cast<ArrayType>(Val: LHS->getType())->getNumElements()
4553 <
4554 cast<ArrayType>(Val: RHS->getType())->getNumElements();
4555}
4556
4557Instruction *InstCombinerImpl::visitLandingPadInst(LandingPadInst &LI) {
4558 // The logic here should be correct for any real-world personality function.
4559 // However if that turns out not to be true, the offending logic can always
4560 // be conditioned on the personality function, like the catch-all logic is.
4561 EHPersonality Personality =
4562 classifyEHPersonality(Pers: LI.getParent()->getParent()->getPersonalityFn());
4563
4564 // Simplify the list of clauses, eg by removing repeated catch clauses
4565 // (these are often created by inlining).
4566 bool MakeNewInstruction = false; // If true, recreate using the following:
4567 SmallVector<Constant *, 16> NewClauses; // - Clauses for the new instruction;
4568 bool CleanupFlag = LI.isCleanup(); // - The new instruction is a cleanup.
4569
4570 SmallPtrSet<Value *, 16> AlreadyCaught; // Typeinfos known caught already.
4571 for (unsigned i = 0, e = LI.getNumClauses(); i != e; ++i) {
4572 bool isLastClause = i + 1 == e;
4573 if (LI.isCatch(Idx: i)) {
4574 // A catch clause.
4575 Constant *CatchClause = LI.getClause(Idx: i);
4576 Constant *TypeInfo = CatchClause->stripPointerCasts();
4577
4578 // If we already saw this clause, there is no point in having a second
4579 // copy of it.
4580 if (AlreadyCaught.insert(Ptr: TypeInfo).second) {
4581 // This catch clause was not already seen.
4582 NewClauses.push_back(Elt: CatchClause);
4583 } else {
4584 // Repeated catch clause - drop the redundant copy.
4585 MakeNewInstruction = true;
4586 }
4587
4588 // If this is a catch-all then there is no point in keeping any following
4589 // clauses or marking the landingpad as having a cleanup.
4590 if (isCatchAll(Personality, TypeInfo)) {
4591 if (!isLastClause)
4592 MakeNewInstruction = true;
4593 CleanupFlag = false;
4594 break;
4595 }
4596 } else {
4597 // A filter clause. If any of the filter elements were already caught
4598 // then they can be dropped from the filter. It is tempting to try to
4599 // exploit the filter further by saying that any typeinfo that does not
4600 // occur in the filter can't be caught later (and thus can be dropped).
4601 // However this would be wrong, since typeinfos can match without being
4602 // equal (for example if one represents a C++ class, and the other some
4603 // class derived from it).
4604 assert(LI.isFilter(i) && "Unsupported landingpad clause!");
4605 Constant *FilterClause = LI.getClause(Idx: i);
4606 ArrayType *FilterType = cast<ArrayType>(Val: FilterClause->getType());
4607 unsigned NumTypeInfos = FilterType->getNumElements();
4608
4609 // An empty filter catches everything, so there is no point in keeping any
4610 // following clauses or marking the landingpad as having a cleanup. By
4611 // dealing with this case here the following code is made a bit simpler.
4612 if (!NumTypeInfos) {
4613 NewClauses.push_back(Elt: FilterClause);
4614 if (!isLastClause)
4615 MakeNewInstruction = true;
4616 CleanupFlag = false;
4617 break;
4618 }
4619
4620 bool MakeNewFilter = false; // If true, make a new filter.
4621 SmallVector<Constant *, 16> NewFilterElts; // New elements.
4622 if (isa<ConstantAggregateZero>(Val: FilterClause)) {
4623 // Not an empty filter - it contains at least one null typeinfo.
4624 assert(NumTypeInfos > 0 && "Should have handled empty filter already!");
4625 Constant *TypeInfo =
4626 Constant::getNullValue(Ty: FilterType->getElementType());
4627 // If this typeinfo is a catch-all then the filter can never match.
4628 if (isCatchAll(Personality, TypeInfo)) {
4629 // Throw the filter away.
4630 MakeNewInstruction = true;
4631 continue;
4632 }
4633
4634 // There is no point in having multiple copies of this typeinfo, so
4635 // discard all but the first copy if there is more than one.
4636 NewFilterElts.push_back(Elt: TypeInfo);
4637 if (NumTypeInfos > 1)
4638 MakeNewFilter = true;
4639 } else {
4640 ConstantArray *Filter = cast<ConstantArray>(Val: FilterClause);
4641 SmallPtrSet<Value *, 16> SeenInFilter; // For uniquing the elements.
4642 NewFilterElts.reserve(N: NumTypeInfos);
4643
4644 // Remove any filter elements that were already caught or that already
4645 // occurred in the filter. While there, see if any of the elements are
4646 // catch-alls. If so, the filter can be discarded.
4647 bool SawCatchAll = false;
4648 for (unsigned j = 0; j != NumTypeInfos; ++j) {
4649 Constant *Elt = Filter->getOperand(i_nocapture: j);
4650 Constant *TypeInfo = Elt->stripPointerCasts();
4651 if (isCatchAll(Personality, TypeInfo)) {
4652 // This element is a catch-all. Bail out, noting this fact.
4653 SawCatchAll = true;
4654 break;
4655 }
4656
4657 // Even if we've seen a type in a catch clause, we don't want to
4658 // remove it from the filter. An unexpected type handler may be
4659 // set up for a call site which throws an exception of the same
4660 // type caught. In order for the exception thrown by the unexpected
4661 // handler to propagate correctly, the filter must be correctly
4662 // described for the call site.
4663 //
4664 // Example:
4665 //
4666 // void unexpected() { throw 1;}
4667 // void foo() throw (int) {
4668 // std::set_unexpected(unexpected);
4669 // try {
4670 // throw 2.0;
4671 // } catch (int i) {}
4672 // }
4673
4674 // There is no point in having multiple copies of the same typeinfo in
4675 // a filter, so only add it if we didn't already.
4676 if (SeenInFilter.insert(Ptr: TypeInfo).second)
4677 NewFilterElts.push_back(Elt: cast<Constant>(Val: Elt));
4678 }
4679 // A filter containing a catch-all cannot match anything by definition.
4680 if (SawCatchAll) {
4681 // Throw the filter away.
4682 MakeNewInstruction = true;
4683 continue;
4684 }
4685
4686 // If we dropped something from the filter, make a new one.
4687 if (NewFilterElts.size() < NumTypeInfos)
4688 MakeNewFilter = true;
4689 }
4690 if (MakeNewFilter) {
4691 FilterType = ArrayType::get(ElementType: FilterType->getElementType(),
4692 NumElements: NewFilterElts.size());
4693 FilterClause = ConstantArray::get(T: FilterType, V: NewFilterElts);
4694 MakeNewInstruction = true;
4695 }
4696
4697 NewClauses.push_back(Elt: FilterClause);
4698
4699 // If the new filter is empty then it will catch everything so there is
4700 // no point in keeping any following clauses or marking the landingpad
4701 // as having a cleanup. The case of the original filter being empty was
4702 // already handled above.
4703 if (MakeNewFilter && !NewFilterElts.size()) {
4704 assert(MakeNewInstruction && "New filter but not a new instruction!");
4705 CleanupFlag = false;
4706 break;
4707 }
4708 }
4709 }
4710
4711 // If several filters occur in a row then reorder them so that the shortest
4712 // filters come first (those with the smallest number of elements). This is
4713 // advantageous because shorter filters are more likely to match, speeding up
4714 // unwinding, but mostly because it increases the effectiveness of the other
4715 // filter optimizations below.
4716 for (unsigned i = 0, e = NewClauses.size(); i + 1 < e; ) {
4717 unsigned j;
4718 // Find the maximal 'j' s.t. the range [i, j) consists entirely of filters.
4719 for (j = i; j != e; ++j)
4720 if (!isa<ArrayType>(Val: NewClauses[j]->getType()))
4721 break;
4722
4723 // Check whether the filters are already sorted by length. We need to know
4724 // if sorting them is actually going to do anything so that we only make a
4725 // new landingpad instruction if it does.
4726 for (unsigned k = i; k + 1 < j; ++k)
4727 if (shorter_filter(LHS: NewClauses[k+1], RHS: NewClauses[k])) {
4728 // Not sorted, so sort the filters now. Doing an unstable sort would be
4729 // correct too but reordering filters pointlessly might confuse users.
4730 std::stable_sort(first: NewClauses.begin() + i, last: NewClauses.begin() + j,
4731 comp: shorter_filter);
4732 MakeNewInstruction = true;
4733 break;
4734 }
4735
4736 // Look for the next batch of filters.
4737 i = j + 1;
4738 }
4739
4740 // If typeinfos matched if and only if equal, then the elements of a filter L
4741 // that occurs later than a filter F could be replaced by the intersection of
4742 // the elements of F and L. In reality two typeinfos can match without being
4743 // equal (for example if one represents a C++ class, and the other some class
4744 // derived from it) so it would be wrong to perform this transform in general.
4745 // However the transform is correct and useful if F is a subset of L. In that
4746 // case L can be replaced by F, and thus removed altogether since repeating a
4747 // filter is pointless. So here we look at all pairs of filters F and L where
4748 // L follows F in the list of clauses, and remove L if every element of F is
4749 // an element of L. This can occur when inlining C++ functions with exception
4750 // specifications.
4751 for (unsigned i = 0; i + 1 < NewClauses.size(); ++i) {
4752 // Examine each filter in turn.
4753 Value *Filter = NewClauses[i];
4754 ArrayType *FTy = dyn_cast<ArrayType>(Val: Filter->getType());
4755 if (!FTy)
4756 // Not a filter - skip it.
4757 continue;
4758 unsigned FElts = FTy->getNumElements();
4759 // Examine each filter following this one. Doing this backwards means that
4760 // we don't have to worry about filters disappearing under us when removed.
4761 for (unsigned j = NewClauses.size() - 1; j != i; --j) {
4762 Value *LFilter = NewClauses[j];
4763 ArrayType *LTy = dyn_cast<ArrayType>(Val: LFilter->getType());
4764 if (!LTy)
4765 // Not a filter - skip it.
4766 continue;
4767 // If Filter is a subset of LFilter, i.e. every element of Filter is also
4768 // an element of LFilter, then discard LFilter.
4769 SmallVectorImpl<Constant *>::iterator J = NewClauses.begin() + j;
4770 // If Filter is empty then it is a subset of LFilter.
4771 if (!FElts) {
4772 // Discard LFilter.
4773 NewClauses.erase(CI: J);
4774 MakeNewInstruction = true;
4775 // Move on to the next filter.
4776 continue;
4777 }
4778 unsigned LElts = LTy->getNumElements();
4779 // If Filter is longer than LFilter then it cannot be a subset of it.
4780 if (FElts > LElts)
4781 // Move on to the next filter.
4782 continue;
4783 // At this point we know that LFilter has at least one element.
4784 if (isa<ConstantAggregateZero>(Val: LFilter)) { // LFilter only contains zeros.
4785 // Filter is a subset of LFilter iff Filter contains only zeros (as we
4786 // already know that Filter is not longer than LFilter).
4787 if (isa<ConstantAggregateZero>(Val: Filter)) {
4788 assert(FElts <= LElts && "Should have handled this case earlier!");
4789 // Discard LFilter.
4790 NewClauses.erase(CI: J);
4791 MakeNewInstruction = true;
4792 }
4793 // Move on to the next filter.
4794 continue;
4795 }
4796 ConstantArray *LArray = cast<ConstantArray>(Val: LFilter);
4797 if (isa<ConstantAggregateZero>(Val: Filter)) { // Filter only contains zeros.
4798 // Since Filter is non-empty and contains only zeros, it is a subset of
4799 // LFilter iff LFilter contains a zero.
4800 assert(FElts > 0 && "Should have eliminated the empty filter earlier!");
4801 for (unsigned l = 0; l != LElts; ++l)
4802 if (LArray->getOperand(i_nocapture: l)->isNullValue()) {
4803 // LFilter contains a zero - discard it.
4804 NewClauses.erase(CI: J);
4805 MakeNewInstruction = true;
4806 break;
4807 }
4808 // Move on to the next filter.
4809 continue;
4810 }
4811 // At this point we know that both filters are ConstantArrays. Loop over
4812 // operands to see whether every element of Filter is also an element of
4813 // LFilter. Since filters tend to be short this is probably faster than
4814 // using a method that scales nicely.
4815 ConstantArray *FArray = cast<ConstantArray>(Val: Filter);
4816 bool AllFound = true;
4817 for (unsigned f = 0; f != FElts; ++f) {
4818 Value *FTypeInfo = FArray->getOperand(i_nocapture: f)->stripPointerCasts();
4819 AllFound = false;
4820 for (unsigned l = 0; l != LElts; ++l) {
4821 Value *LTypeInfo = LArray->getOperand(i_nocapture: l)->stripPointerCasts();
4822 if (LTypeInfo == FTypeInfo) {
4823 AllFound = true;
4824 break;
4825 }
4826 }
4827 if (!AllFound)
4828 break;
4829 }
4830 if (AllFound) {
4831 // Discard LFilter.
4832 NewClauses.erase(CI: J);
4833 MakeNewInstruction = true;
4834 }
4835 // Move on to the next filter.
4836 }
4837 }
4838
4839 // If we changed any of the clauses, replace the old landingpad instruction
4840 // with a new one.
4841 if (MakeNewInstruction) {
4842 LandingPadInst *NLI = LandingPadInst::Create(RetTy: LI.getType(),
4843 NumReservedClauses: NewClauses.size());
4844 for (Constant *C : NewClauses)
4845 NLI->addClause(ClauseVal: C);
4846 // A landing pad with no clauses must have the cleanup flag set. It is
4847 // theoretically possible, though highly unlikely, that we eliminated all
4848 // clauses. If so, force the cleanup flag to true.
4849 if (NewClauses.empty())
4850 CleanupFlag = true;
4851 NLI->setCleanup(CleanupFlag);
4852 return NLI;
4853 }
4854
4855 // Even if none of the clauses changed, we may nonetheless have understood
4856 // that the cleanup flag is pointless. Clear it if so.
4857 if (LI.isCleanup() != CleanupFlag) {
4858 assert(!CleanupFlag && "Adding a cleanup, not removing one?!");
4859 LI.setCleanup(CleanupFlag);
4860 return &LI;
4861 }
4862
4863 return nullptr;
4864}
4865
4866Value *
4867InstCombinerImpl::pushFreezeToPreventPoisonFromPropagating(FreezeInst &OrigFI) {
4868 // Try to push freeze through instructions that propagate but don't produce
4869 // poison as far as possible. If an operand of freeze follows three
4870 // conditions 1) one-use, 2) does not produce poison, and 3) has all but one
4871 // guaranteed-non-poison operands then push the freeze through to the one
4872 // operand that is not guaranteed non-poison. The actual transform is as
4873 // follows.
4874 // Op1 = ... ; Op1 can be posion
4875 // Op0 = Inst(Op1, NonPoisonOps...) ; Op0 has only one use and only have
4876 // ; single guaranteed-non-poison operands
4877 // ... = Freeze(Op0)
4878 // =>
4879 // Op1 = ...
4880 // Op1.fr = Freeze(Op1)
4881 // ... = Inst(Op1.fr, NonPoisonOps...)
4882 auto *OrigOp = OrigFI.getOperand(i_nocapture: 0);
4883 auto *OrigOpInst = dyn_cast<Instruction>(Val: OrigOp);
4884
4885 // While we could change the other users of OrigOp to use freeze(OrigOp), that
4886 // potentially reduces their optimization potential, so let's only do this iff
4887 // the OrigOp is only used by the freeze.
4888 if (!OrigOpInst || !OrigOpInst->hasOneUse() || isa<PHINode>(Val: OrigOp))
4889 return nullptr;
4890
4891 // We can't push the freeze through an instruction which can itself create
4892 // poison. If the only source of new poison is flags, we can simply
4893 // strip them (since we know the only use is the freeze and nothing can
4894 // benefit from them.)
4895 if (canCreateUndefOrPoison(Op: cast<Operator>(Val: OrigOp),
4896 /*ConsiderFlagsAndMetadata*/ false))
4897 return nullptr;
4898
4899 // If operand is guaranteed not to be poison, there is no need to add freeze
4900 // to the operand. So we first find the operand that is not guaranteed to be
4901 // poison.
4902 Use *MaybePoisonOperand = nullptr;
4903 for (Use &U : OrigOpInst->operands()) {
4904 if (isa<MetadataAsValue>(Val: U.get()) ||
4905 isGuaranteedNotToBeUndefOrPoison(V: U.get()))
4906 continue;
4907 if (!MaybePoisonOperand)
4908 MaybePoisonOperand = &U;
4909 else
4910 return nullptr;
4911 }
4912
4913 OrigOpInst->dropPoisonGeneratingAnnotations();
4914
4915 // If all operands are guaranteed to be non-poison, we can drop freeze.
4916 if (!MaybePoisonOperand)
4917 return OrigOp;
4918
4919 Builder.SetInsertPoint(OrigOpInst);
4920 auto *FrozenMaybePoisonOperand = Builder.CreateFreeze(
4921 V: MaybePoisonOperand->get(), Name: MaybePoisonOperand->get()->getName() + ".fr");
4922
4923 replaceUse(U&: *MaybePoisonOperand, NewValue: FrozenMaybePoisonOperand);
4924 return OrigOp;
4925}
4926
4927Instruction *InstCombinerImpl::foldFreezeIntoRecurrence(FreezeInst &FI,
4928 PHINode *PN) {
4929 // Detect whether this is a recurrence with a start value and some number of
4930 // backedge values. We'll check whether we can push the freeze through the
4931 // backedge values (possibly dropping poison flags along the way) until we
4932 // reach the phi again. In that case, we can move the freeze to the start
4933 // value.
4934 Use *StartU = nullptr;
4935 SmallVector<Value *> Worklist;
4936 for (Use &U : PN->incoming_values()) {
4937 if (DT.dominates(A: PN->getParent(), B: PN->getIncomingBlock(U))) {
4938 // Add backedge value to worklist.
4939 Worklist.push_back(Elt: U.get());
4940 continue;
4941 }
4942
4943 // Don't bother handling multiple start values.
4944 if (StartU)
4945 return nullptr;
4946 StartU = &U;
4947 }
4948
4949 if (!StartU || Worklist.empty())
4950 return nullptr; // Not a recurrence.
4951
4952 Value *StartV = StartU->get();
4953 BasicBlock *StartBB = PN->getIncomingBlock(U: *StartU);
4954 bool StartNeedsFreeze = !isGuaranteedNotToBeUndefOrPoison(V: StartV);
4955 // We can't insert freeze if the start value is the result of the
4956 // terminator (e.g. an invoke).
4957 if (StartNeedsFreeze && StartBB->getTerminator() == StartV)
4958 return nullptr;
4959
4960 SmallPtrSet<Value *, 32> Visited;
4961 SmallVector<Instruction *> DropFlags;
4962 while (!Worklist.empty()) {
4963 Value *V = Worklist.pop_back_val();
4964 if (!Visited.insert(Ptr: V).second)
4965 continue;
4966
4967 if (Visited.size() > 32)
4968 return nullptr; // Limit the total number of values we inspect.
4969
4970 // Assume that PN is non-poison, because it will be after the transform.
4971 if (V == PN || isGuaranteedNotToBeUndefOrPoison(V))
4972 continue;
4973
4974 Instruction *I = dyn_cast<Instruction>(Val: V);
4975 if (!I || canCreateUndefOrPoison(Op: cast<Operator>(Val: I),
4976 /*ConsiderFlagsAndMetadata*/ false))
4977 return nullptr;
4978
4979 DropFlags.push_back(Elt: I);
4980 append_range(C&: Worklist, R: I->operands());
4981 }
4982
4983 for (Instruction *I : DropFlags)
4984 I->dropPoisonGeneratingAnnotations();
4985
4986 if (StartNeedsFreeze) {
4987 Builder.SetInsertPoint(StartBB->getTerminator());
4988 Value *FrozenStartV = Builder.CreateFreeze(V: StartV,
4989 Name: StartV->getName() + ".fr");
4990 replaceUse(U&: *StartU, NewValue: FrozenStartV);
4991 }
4992 return replaceInstUsesWith(I&: FI, V: PN);
4993}
4994
4995bool InstCombinerImpl::freezeOtherUses(FreezeInst &FI) {
4996 Value *Op = FI.getOperand(i_nocapture: 0);
4997
4998 if (isa<Constant>(Val: Op) || Op->hasOneUse())
4999 return false;
5000
5001 // Move the freeze directly after the definition of its operand, so that
5002 // it dominates the maximum number of uses. Note that it may not dominate
5003 // *all* uses if the operand is an invoke/callbr and the use is in a phi on
5004 // the normal/default destination. This is why the domination check in the
5005 // replacement below is still necessary.
5006 BasicBlock::iterator MoveBefore;
5007 if (isa<Argument>(Val: Op)) {
5008 MoveBefore =
5009 FI.getFunction()->getEntryBlock().getFirstNonPHIOrDbgOrAlloca();
5010 } else {
5011 auto MoveBeforeOpt = cast<Instruction>(Val: Op)->getInsertionPointAfterDef();
5012 if (!MoveBeforeOpt)
5013 return false;
5014 MoveBefore = *MoveBeforeOpt;
5015 }
5016
5017 // Re-point iterator to come after any debug-info records.
5018 MoveBefore.setHeadBit(false);
5019
5020 bool Changed = false;
5021 if (&FI != &*MoveBefore) {
5022 FI.moveBefore(BB&: *MoveBefore->getParent(), I: MoveBefore);
5023 Changed = true;
5024 }
5025
5026 Op->replaceUsesWithIf(New: &FI, ShouldReplace: [&](Use &U) -> bool {
5027 bool Dominates = DT.dominates(Def: &FI, U);
5028 Changed |= Dominates;
5029 return Dominates;
5030 });
5031
5032 return Changed;
5033}
5034
5035// Check if any direct or bitcast user of this value is a shuffle instruction.
5036static bool isUsedWithinShuffleVector(Value *V) {
5037 for (auto *U : V->users()) {
5038 if (isa<ShuffleVectorInst>(Val: U))
5039 return true;
5040 else if (match(V: U, P: m_BitCast(Op: m_Specific(V))) && isUsedWithinShuffleVector(V: U))
5041 return true;
5042 }
5043 return false;
5044}
5045
5046Instruction *InstCombinerImpl::visitFreeze(FreezeInst &I) {
5047 Value *Op0 = I.getOperand(i_nocapture: 0);
5048
5049 if (Value *V = simplifyFreezeInst(Op: Op0, Q: SQ.getWithInstruction(I: &I)))
5050 return replaceInstUsesWith(I, V);
5051
5052 // freeze (phi const, x) --> phi const, (freeze x)
5053 if (auto *PN = dyn_cast<PHINode>(Val: Op0)) {
5054 if (Instruction *NV = foldOpIntoPhi(I, PN))
5055 return NV;
5056 if (Instruction *NV = foldFreezeIntoRecurrence(FI&: I, PN))
5057 return NV;
5058 }
5059
5060 if (Value *NI = pushFreezeToPreventPoisonFromPropagating(OrigFI&: I))
5061 return replaceInstUsesWith(I, V: NI);
5062
5063 // If I is freeze(undef), check its uses and fold it to a fixed constant.
5064 // - or: pick -1
5065 // - select's condition: if the true value is constant, choose it by making
5066 // the condition true.
5067 // - default: pick 0
5068 //
5069 // Note that this transform is intentionally done here rather than
5070 // via an analysis in InstSimplify or at individual user sites. That is
5071 // because we must produce the same value for all uses of the freeze -
5072 // it's the reason "freeze" exists!
5073 //
5074 // TODO: This could use getBinopAbsorber() / getBinopIdentity() to avoid
5075 // duplicating logic for binops at least.
5076 auto getUndefReplacement = [&](Type *Ty) {
5077 Value *BestValue = nullptr;
5078 Value *NullValue = Constant::getNullValue(Ty);
5079 for (const auto *U : I.users()) {
5080 Value *V = NullValue;
5081 if (match(V: U, P: m_Or(L: m_Value(), R: m_Value())))
5082 V = ConstantInt::getAllOnesValue(Ty);
5083 else if (match(V: U, P: m_Select(C: m_Specific(V: &I), L: m_Constant(), R: m_Value())))
5084 V = ConstantInt::getTrue(Ty);
5085 else if (match(V: U, P: m_c_Select(L: m_Specific(V: &I), R: m_Value(V)))) {
5086 if (!isGuaranteedNotToBeUndefOrPoison(V, AC: &AC, CtxI: &I, DT: &DT))
5087 V = NullValue;
5088 }
5089
5090 if (!BestValue)
5091 BestValue = V;
5092 else if (BestValue != V)
5093 BestValue = NullValue;
5094 }
5095 assert(BestValue && "Must have at least one use");
5096 return BestValue;
5097 };
5098
5099 if (match(V: Op0, P: m_Undef())) {
5100 // Don't fold freeze(undef/poison) if it's used as a vector operand in
5101 // a shuffle. This may improve codegen for shuffles that allow
5102 // unspecified inputs.
5103 if (isUsedWithinShuffleVector(V: &I))
5104 return nullptr;
5105 return replaceInstUsesWith(I, V: getUndefReplacement(I.getType()));
5106 }
5107
5108 auto getFreezeVectorReplacement = [](Constant *C) -> Constant * {
5109 Type *Ty = C->getType();
5110 auto *VTy = dyn_cast<FixedVectorType>(Val: Ty);
5111 if (!VTy)
5112 return nullptr;
5113 unsigned NumElts = VTy->getNumElements();
5114 Constant *BestValue = Constant::getNullValue(Ty: VTy->getScalarType());
5115 for (unsigned i = 0; i != NumElts; ++i) {
5116 Constant *EltC = C->getAggregateElement(Elt: i);
5117 if (EltC && !match(V: EltC, P: m_Undef())) {
5118 BestValue = EltC;
5119 break;
5120 }
5121 }
5122 return Constant::replaceUndefsWith(C, Replacement: BestValue);
5123 };
5124
5125 Constant *C;
5126 if (match(V: Op0, P: m_Constant(C)) && C->containsUndefOrPoisonElement() &&
5127 !C->containsConstantExpression()) {
5128 if (Constant *Repl = getFreezeVectorReplacement(C))
5129 return replaceInstUsesWith(I, V: Repl);
5130 }
5131
5132 // Replace uses of Op with freeze(Op).
5133 if (freezeOtherUses(FI&: I))
5134 return &I;
5135
5136 return nullptr;
5137}
5138
5139/// Check for case where the call writes to an otherwise dead alloca. This
5140/// shows up for unused out-params in idiomatic C/C++ code. Note that this
5141/// helper *only* analyzes the write; doesn't check any other legality aspect.
5142static bool SoleWriteToDeadLocal(Instruction *I, TargetLibraryInfo &TLI) {
5143 auto *CB = dyn_cast<CallBase>(Val: I);
5144 if (!CB)
5145 // TODO: handle e.g. store to alloca here - only worth doing if we extend
5146 // to allow reload along used path as described below. Otherwise, this
5147 // is simply a store to a dead allocation which will be removed.
5148 return false;
5149 std::optional<MemoryLocation> Dest = MemoryLocation::getForDest(CI: CB, TLI);
5150 if (!Dest)
5151 return false;
5152 auto *AI = dyn_cast<AllocaInst>(Val: getUnderlyingObject(V: Dest->Ptr));
5153 if (!AI)
5154 // TODO: allow malloc?
5155 return false;
5156 // TODO: allow memory access dominated by move point? Note that since AI
5157 // could have a reference to itself captured by the call, we would need to
5158 // account for cycles in doing so.
5159 SmallVector<const User *> AllocaUsers;
5160 SmallPtrSet<const User *, 4> Visited;
5161 auto pushUsers = [&](const Instruction &I) {
5162 for (const User *U : I.users()) {
5163 if (Visited.insert(Ptr: U).second)
5164 AllocaUsers.push_back(Elt: U);
5165 }
5166 };
5167 pushUsers(*AI);
5168 while (!AllocaUsers.empty()) {
5169 auto *UserI = cast<Instruction>(Val: AllocaUsers.pop_back_val());
5170 if (isa<GetElementPtrInst>(Val: UserI) || isa<AddrSpaceCastInst>(Val: UserI)) {
5171 pushUsers(*UserI);
5172 continue;
5173 }
5174 if (UserI == CB)
5175 continue;
5176 // TODO: support lifetime.start/end here
5177 return false;
5178 }
5179 return true;
5180}
5181
5182/// Try to move the specified instruction from its current block into the
5183/// beginning of DestBlock, which can only happen if it's safe to move the
5184/// instruction past all of the instructions between it and the end of its
5185/// block.
5186bool InstCombinerImpl::tryToSinkInstruction(Instruction *I,
5187 BasicBlock *DestBlock) {
5188 BasicBlock *SrcBlock = I->getParent();
5189
5190 // Cannot move control-flow-involving, volatile loads, vaarg, etc.
5191 if (isa<PHINode>(Val: I) || I->isEHPad() || I->mayThrow() || !I->willReturn() ||
5192 I->isTerminator())
5193 return false;
5194
5195 // Do not sink static or dynamic alloca instructions. Static allocas must
5196 // remain in the entry block, and dynamic allocas must not be sunk in between
5197 // a stacksave / stackrestore pair, which would incorrectly shorten its
5198 // lifetime.
5199 if (isa<AllocaInst>(Val: I))
5200 return false;
5201
5202 // Do not sink into catchswitch blocks.
5203 if (isa<CatchSwitchInst>(Val: DestBlock->getTerminator()))
5204 return false;
5205
5206 // Do not sink convergent call instructions.
5207 if (auto *CI = dyn_cast<CallInst>(Val: I)) {
5208 if (CI->isConvergent())
5209 return false;
5210 }
5211
5212 // Unless we can prove that the memory write isn't visibile except on the
5213 // path we're sinking to, we must bail.
5214 if (I->mayWriteToMemory()) {
5215 if (!SoleWriteToDeadLocal(I, TLI))
5216 return false;
5217 }
5218
5219 // We can only sink load instructions if there is nothing between the load and
5220 // the end of block that could change the value.
5221 if (I->mayReadFromMemory() &&
5222 !I->hasMetadata(KindID: LLVMContext::MD_invariant_load)) {
5223 // We don't want to do any sophisticated alias analysis, so we only check
5224 // the instructions after I in I's parent block if we try to sink to its
5225 // successor block.
5226 if (DestBlock->getUniquePredecessor() != I->getParent())
5227 return false;
5228 for (BasicBlock::iterator Scan = std::next(x: I->getIterator()),
5229 E = I->getParent()->end();
5230 Scan != E; ++Scan)
5231 if (Scan->mayWriteToMemory())
5232 return false;
5233 }
5234
5235 I->dropDroppableUses(ShouldDrop: [&](const Use *U) {
5236 auto *I = dyn_cast<Instruction>(Val: U->getUser());
5237 if (I && I->getParent() != DestBlock) {
5238 Worklist.add(I);
5239 return true;
5240 }
5241 return false;
5242 });
5243 /// FIXME: We could remove droppable uses that are not dominated by
5244 /// the new position.
5245
5246 BasicBlock::iterator InsertPos = DestBlock->getFirstInsertionPt();
5247 I->moveBefore(BB&: *DestBlock, I: InsertPos);
5248 ++NumSunkInst;
5249
5250 // Also sink all related debug uses from the source basic block. Otherwise we
5251 // get debug use before the def. Attempt to salvage debug uses first, to
5252 // maximise the range variables have location for. If we cannot salvage, then
5253 // mark the location undef: we know it was supposed to receive a new location
5254 // here, but that computation has been sunk.
5255 SmallVector<DbgVariableIntrinsic *, 2> DbgUsers;
5256 SmallVector<DbgVariableRecord *, 2> DbgVariableRecords;
5257 findDbgUsers(DbgInsts&: DbgUsers, V: I, DbgVariableRecords: &DbgVariableRecords);
5258 if (!DbgUsers.empty())
5259 tryToSinkInstructionDbgValues(I, InsertPos, SrcBlock, DestBlock, DbgUsers);
5260 if (!DbgVariableRecords.empty())
5261 tryToSinkInstructionDbgVariableRecords(I, InsertPos, SrcBlock, DestBlock,
5262 DPUsers&: DbgVariableRecords);
5263
5264 // PS: there are numerous flaws with this behaviour, not least that right now
5265 // assignments can be re-ordered past other assignments to the same variable
5266 // if they use different Values. Creating more undef assignements can never be
5267 // undone. And salvaging all users outside of this block can un-necessarily
5268 // alter the lifetime of the live-value that the variable refers to.
5269 // Some of these things can be resolved by tolerating debug use-before-defs in
5270 // LLVM-IR, however it depends on the instruction-referencing CodeGen backend
5271 // being used for more architectures.
5272
5273 return true;
5274}
5275
5276void InstCombinerImpl::tryToSinkInstructionDbgValues(
5277 Instruction *I, BasicBlock::iterator InsertPos, BasicBlock *SrcBlock,
5278 BasicBlock *DestBlock, SmallVectorImpl<DbgVariableIntrinsic *> &DbgUsers) {
5279 // For all debug values in the destination block, the sunk instruction
5280 // will still be available, so they do not need to be dropped.
5281 SmallVector<DbgVariableIntrinsic *, 2> DbgUsersToSalvage;
5282 for (auto &DbgUser : DbgUsers)
5283 if (DbgUser->getParent() != DestBlock)
5284 DbgUsersToSalvage.push_back(Elt: DbgUser);
5285
5286 // Process the sinking DbgUsersToSalvage in reverse order, as we only want
5287 // to clone the last appearing debug intrinsic for each given variable.
5288 SmallVector<DbgVariableIntrinsic *, 2> DbgUsersToSink;
5289 for (DbgVariableIntrinsic *DVI : DbgUsersToSalvage)
5290 if (DVI->getParent() == SrcBlock)
5291 DbgUsersToSink.push_back(Elt: DVI);
5292 llvm::sort(C&: DbgUsersToSink,
5293 Comp: [](auto *A, auto *B) { return B->comesBefore(A); });
5294
5295 SmallVector<DbgVariableIntrinsic *, 2> DIIClones;
5296 SmallSet<DebugVariable, 4> SunkVariables;
5297 for (auto *User : DbgUsersToSink) {
5298 // A dbg.declare instruction should not be cloned, since there can only be
5299 // one per variable fragment. It should be left in the original place
5300 // because the sunk instruction is not an alloca (otherwise we could not be
5301 // here).
5302 if (isa<DbgDeclareInst>(Val: User))
5303 continue;
5304
5305 DebugVariable DbgUserVariable =
5306 DebugVariable(User->getVariable(), User->getExpression(),
5307 User->getDebugLoc()->getInlinedAt());
5308
5309 if (!SunkVariables.insert(V: DbgUserVariable).second)
5310 continue;
5311
5312 // Leave dbg.assign intrinsics in their original positions and there should
5313 // be no need to insert a clone.
5314 if (isa<DbgAssignIntrinsic>(Val: User))
5315 continue;
5316
5317 DIIClones.emplace_back(Args: cast<DbgVariableIntrinsic>(Val: User->clone()));
5318 if (isa<DbgDeclareInst>(Val: User) && isa<CastInst>(Val: I))
5319 DIIClones.back()->replaceVariableLocationOp(OldValue: I, NewValue: I->getOperand(i: 0));
5320 LLVM_DEBUG(dbgs() << "CLONE: " << *DIIClones.back() << '\n');
5321 }
5322
5323 // Perform salvaging without the clones, then sink the clones.
5324 if (!DIIClones.empty()) {
5325 salvageDebugInfoForDbgValues(I&: *I, Insns: DbgUsersToSalvage, DPInsns: {});
5326 // The clones are in reverse order of original appearance, reverse again to
5327 // maintain the original order.
5328 for (auto &DIIClone : llvm::reverse(C&: DIIClones)) {
5329 DIIClone->insertBefore(InsertPos);
5330 LLVM_DEBUG(dbgs() << "SINK: " << *DIIClone << '\n');
5331 }
5332 }
5333}
5334
5335void InstCombinerImpl::tryToSinkInstructionDbgVariableRecords(
5336 Instruction *I, BasicBlock::iterator InsertPos, BasicBlock *SrcBlock,
5337 BasicBlock *DestBlock,
5338 SmallVectorImpl<DbgVariableRecord *> &DbgVariableRecords) {
5339 // Implementation of tryToSinkInstructionDbgValues, but for the
5340 // DbgVariableRecord of variable assignments rather than dbg.values.
5341
5342 // Fetch all DbgVariableRecords not already in the destination.
5343 SmallVector<DbgVariableRecord *, 2> DbgVariableRecordsToSalvage;
5344 for (auto &DVR : DbgVariableRecords)
5345 if (DVR->getParent() != DestBlock)
5346 DbgVariableRecordsToSalvage.push_back(Elt: DVR);
5347
5348 // Fetch a second collection, of DbgVariableRecords in the source block that
5349 // we're going to sink.
5350 SmallVector<DbgVariableRecord *> DbgVariableRecordsToSink;
5351 for (DbgVariableRecord *DVR : DbgVariableRecordsToSalvage)
5352 if (DVR->getParent() == SrcBlock)
5353 DbgVariableRecordsToSink.push_back(Elt: DVR);
5354
5355 // Sort DbgVariableRecords according to their position in the block. This is a
5356 // partial order: DbgVariableRecords attached to different instructions will
5357 // be ordered by the instruction order, but DbgVariableRecords attached to the
5358 // same instruction won't have an order.
5359 auto Order = [](DbgVariableRecord *A, DbgVariableRecord *B) -> bool {
5360 return B->getInstruction()->comesBefore(Other: A->getInstruction());
5361 };
5362 llvm::stable_sort(Range&: DbgVariableRecordsToSink, C: Order);
5363
5364 // If there are two assignments to the same variable attached to the same
5365 // instruction, the ordering between the two assignments is important. Scan
5366 // for this (rare) case and establish which is the last assignment.
5367 using InstVarPair = std::pair<const Instruction *, DebugVariable>;
5368 SmallDenseMap<InstVarPair, DbgVariableRecord *> FilterOutMap;
5369 if (DbgVariableRecordsToSink.size() > 1) {
5370 SmallDenseMap<InstVarPair, unsigned> CountMap;
5371 // Count how many assignments to each variable there is per instruction.
5372 for (DbgVariableRecord *DVR : DbgVariableRecordsToSink) {
5373 DebugVariable DbgUserVariable =
5374 DebugVariable(DVR->getVariable(), DVR->getExpression(),
5375 DVR->getDebugLoc()->getInlinedAt());
5376 CountMap[std::make_pair(x: DVR->getInstruction(), y&: DbgUserVariable)] += 1;
5377 }
5378
5379 // If there are any instructions with two assignments, add them to the
5380 // FilterOutMap to record that they need extra filtering.
5381 SmallPtrSet<const Instruction *, 4> DupSet;
5382 for (auto It : CountMap) {
5383 if (It.second > 1) {
5384 FilterOutMap[It.first] = nullptr;
5385 DupSet.insert(Ptr: It.first.first);
5386 }
5387 }
5388
5389 // For all instruction/variable pairs needing extra filtering, find the
5390 // latest assignment.
5391 for (const Instruction *Inst : DupSet) {
5392 for (DbgVariableRecord &DVR :
5393 llvm::reverse(C: filterDbgVars(R: Inst->getDbgRecordRange()))) {
5394 DebugVariable DbgUserVariable =
5395 DebugVariable(DVR.getVariable(), DVR.getExpression(),
5396 DVR.getDebugLoc()->getInlinedAt());
5397 auto FilterIt =
5398 FilterOutMap.find(Val: std::make_pair(x&: Inst, y&: DbgUserVariable));
5399 if (FilterIt == FilterOutMap.end())
5400 continue;
5401 if (FilterIt->second != nullptr)
5402 continue;
5403 FilterIt->second = &DVR;
5404 }
5405 }
5406 }
5407
5408 // Perform cloning of the DbgVariableRecords that we plan on sinking, filter
5409 // out any duplicate assignments identified above.
5410 SmallVector<DbgVariableRecord *, 2> DVRClones;
5411 SmallSet<DebugVariable, 4> SunkVariables;
5412 for (DbgVariableRecord *DVR : DbgVariableRecordsToSink) {
5413 if (DVR->Type == DbgVariableRecord::LocationType::Declare)
5414 continue;
5415
5416 DebugVariable DbgUserVariable =
5417 DebugVariable(DVR->getVariable(), DVR->getExpression(),
5418 DVR->getDebugLoc()->getInlinedAt());
5419
5420 // For any variable where there were multiple assignments in the same place,
5421 // ignore all but the last assignment.
5422 if (!FilterOutMap.empty()) {
5423 InstVarPair IVP = std::make_pair(x: DVR->getInstruction(), y&: DbgUserVariable);
5424 auto It = FilterOutMap.find(Val: IVP);
5425
5426 // Filter out.
5427 if (It != FilterOutMap.end() && It->second != DVR)
5428 continue;
5429 }
5430
5431 if (!SunkVariables.insert(V: DbgUserVariable).second)
5432 continue;
5433
5434 if (DVR->isDbgAssign())
5435 continue;
5436
5437 DVRClones.emplace_back(Args: DVR->clone());
5438 LLVM_DEBUG(dbgs() << "CLONE: " << *DVRClones.back() << '\n');
5439 }
5440
5441 // Perform salvaging without the clones, then sink the clones.
5442 if (DVRClones.empty())
5443 return;
5444
5445 salvageDebugInfoForDbgValues(I&: *I, Insns: {}, DPInsns: DbgVariableRecordsToSalvage);
5446
5447 // The clones are in reverse order of original appearance. Assert that the
5448 // head bit is set on the iterator as we _should_ have received it via
5449 // getFirstInsertionPt. Inserting like this will reverse the clone order as
5450 // we'll repeatedly insert at the head, such as:
5451 // DVR-3 (third insertion goes here)
5452 // DVR-2 (second insertion goes here)
5453 // DVR-1 (first insertion goes here)
5454 // Any-Prior-DVRs
5455 // InsertPtInst
5456 assert(InsertPos.getHeadBit());
5457 for (DbgVariableRecord *DVRClone : DVRClones) {
5458 InsertPos->getParent()->insertDbgRecordBefore(DR: DVRClone, Here: InsertPos);
5459 LLVM_DEBUG(dbgs() << "SINK: " << *DVRClone << '\n');
5460 }
5461}
5462
5463bool InstCombinerImpl::run() {
5464 while (!Worklist.isEmpty()) {
5465 // Walk deferred instructions in reverse order, and push them to the
5466 // worklist, which means they'll end up popped from the worklist in-order.
5467 while (Instruction *I = Worklist.popDeferred()) {
5468 // Check to see if we can DCE the instruction. We do this already here to
5469 // reduce the number of uses and thus allow other folds to trigger.
5470 // Note that eraseInstFromFunction() may push additional instructions on
5471 // the deferred worklist, so this will DCE whole instruction chains.
5472 if (isInstructionTriviallyDead(I, TLI: &TLI)) {
5473 eraseInstFromFunction(I&: *I);
5474 ++NumDeadInst;
5475 continue;
5476 }
5477
5478 Worklist.push(I);
5479 }
5480
5481 Instruction *I = Worklist.removeOne();
5482 if (I == nullptr) continue; // skip null values.
5483
5484 // Check to see if we can DCE the instruction.
5485 if (isInstructionTriviallyDead(I, TLI: &TLI)) {
5486 eraseInstFromFunction(I&: *I);
5487 ++NumDeadInst;
5488 continue;
5489 }
5490
5491 if (!DebugCounter::shouldExecute(CounterName: VisitCounter))
5492 continue;
5493
5494 // See if we can trivially sink this instruction to its user if we can
5495 // prove that the successor is not executed more frequently than our block.
5496 // Return the UserBlock if successful.
5497 auto getOptionalSinkBlockForInst =
5498 [this](Instruction *I) -> std::optional<BasicBlock *> {
5499 if (!EnableCodeSinking)
5500 return std::nullopt;
5501
5502 BasicBlock *BB = I->getParent();
5503 BasicBlock *UserParent = nullptr;
5504 unsigned NumUsers = 0;
5505
5506 for (Use &U : I->uses()) {
5507 User *User = U.getUser();
5508 if (User->isDroppable())
5509 continue;
5510 if (NumUsers > MaxSinkNumUsers)
5511 return std::nullopt;
5512
5513 Instruction *UserInst = cast<Instruction>(Val: User);
5514 // Special handling for Phi nodes - get the block the use occurs in.
5515 BasicBlock *UserBB = UserInst->getParent();
5516 if (PHINode *PN = dyn_cast<PHINode>(Val: UserInst))
5517 UserBB = PN->getIncomingBlock(U);
5518 // Bail out if we have uses in different blocks. We don't do any
5519 // sophisticated analysis (i.e finding NearestCommonDominator of these
5520 // use blocks).
5521 if (UserParent && UserParent != UserBB)
5522 return std::nullopt;
5523 UserParent = UserBB;
5524
5525 // Make sure these checks are done only once, naturally we do the checks
5526 // the first time we get the userparent, this will save compile time.
5527 if (NumUsers == 0) {
5528 // Try sinking to another block. If that block is unreachable, then do
5529 // not bother. SimplifyCFG should handle it.
5530 if (UserParent == BB || !DT.isReachableFromEntry(A: UserParent))
5531 return std::nullopt;
5532
5533 auto *Term = UserParent->getTerminator();
5534 // See if the user is one of our successors that has only one
5535 // predecessor, so that we don't have to split the critical edge.
5536 // Another option where we can sink is a block that ends with a
5537 // terminator that does not pass control to other block (such as
5538 // return or unreachable or resume). In this case:
5539 // - I dominates the User (by SSA form);
5540 // - the User will be executed at most once.
5541 // So sinking I down to User is always profitable or neutral.
5542 if (UserParent->getUniquePredecessor() != BB && !succ_empty(I: Term))
5543 return std::nullopt;
5544
5545 assert(DT.dominates(BB, UserParent) && "Dominance relation broken?");
5546 }
5547
5548 NumUsers++;
5549 }
5550
5551 // No user or only has droppable users.
5552 if (!UserParent)
5553 return std::nullopt;
5554
5555 return UserParent;
5556 };
5557
5558 auto OptBB = getOptionalSinkBlockForInst(I);
5559 if (OptBB) {
5560 auto *UserParent = *OptBB;
5561 // Okay, the CFG is simple enough, try to sink this instruction.
5562 if (tryToSinkInstruction(I, DestBlock: UserParent)) {
5563 LLVM_DEBUG(dbgs() << "IC: Sink: " << *I << '\n');
5564 MadeIRChange = true;
5565 // We'll add uses of the sunk instruction below, but since
5566 // sinking can expose opportunities for it's *operands* add
5567 // them to the worklist
5568 for (Use &U : I->operands())
5569 if (Instruction *OpI = dyn_cast<Instruction>(Val: U.get()))
5570 Worklist.push(I: OpI);
5571 }
5572 }
5573
5574 // Now that we have an instruction, try combining it to simplify it.
5575 Builder.SetInsertPoint(I);
5576 Builder.CollectMetadataToCopy(
5577 Src: I, MetadataKinds: {LLVMContext::MD_dbg, LLVMContext::MD_annotation});
5578
5579#ifndef NDEBUG
5580 std::string OrigI;
5581#endif
5582 LLVM_DEBUG(raw_string_ostream SS(OrigI); I->print(SS););
5583 LLVM_DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
5584
5585 if (Instruction *Result = visit(I&: *I)) {
5586 ++NumCombined;
5587 // Should we replace the old instruction with a new one?
5588 if (Result != I) {
5589 LLVM_DEBUG(dbgs() << "IC: Old = " << *I << '\n'
5590 << " New = " << *Result << '\n');
5591
5592 // We copy the old instruction's DebugLoc to the new instruction, unless
5593 // InstCombine already assigned a DebugLoc to it, in which case we
5594 // should trust the more specifically selected DebugLoc.
5595 Result->setDebugLoc(Result->getDebugLoc().orElse(Other: I->getDebugLoc()));
5596 // We also copy annotation metadata to the new instruction.
5597 Result->copyMetadata(SrcInst: *I, WL: LLVMContext::MD_annotation);
5598 // Everything uses the new instruction now.
5599 I->replaceAllUsesWith(V: Result);
5600
5601 // Move the name to the new instruction first.
5602 Result->takeName(V: I);
5603
5604 // Insert the new instruction into the basic block...
5605 BasicBlock *InstParent = I->getParent();
5606 BasicBlock::iterator InsertPos = I->getIterator();
5607
5608 // Are we replace a PHI with something that isn't a PHI, or vice versa?
5609 if (isa<PHINode>(Val: Result) != isa<PHINode>(Val: I)) {
5610 // We need to fix up the insertion point.
5611 if (isa<PHINode>(Val: I)) // PHI -> Non-PHI
5612 InsertPos = InstParent->getFirstInsertionPt();
5613 else // Non-PHI -> PHI
5614 InsertPos = InstParent->getFirstNonPHIIt();
5615 }
5616
5617 Result->insertInto(ParentBB: InstParent, It: InsertPos);
5618
5619 // Push the new instruction and any users onto the worklist.
5620 Worklist.pushUsersToWorkList(I&: *Result);
5621 Worklist.push(I: Result);
5622
5623 eraseInstFromFunction(I&: *I);
5624 } else {
5625 LLVM_DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
5626 << " New = " << *I << '\n');
5627
5628 // If the instruction was modified, it's possible that it is now dead.
5629 // if so, remove it.
5630 if (isInstructionTriviallyDead(I, TLI: &TLI)) {
5631 eraseInstFromFunction(I&: *I);
5632 } else {
5633 Worklist.pushUsersToWorkList(I&: *I);
5634 Worklist.push(I);
5635 }
5636 }
5637 MadeIRChange = true;
5638 }
5639 }
5640
5641 Worklist.zap();
5642 return MadeIRChange;
5643}
5644
5645// Track the scopes used by !alias.scope and !noalias. In a function, a
5646// @llvm.experimental.noalias.scope.decl is only useful if that scope is used
5647// by both sets. If not, the declaration of the scope can be safely omitted.
5648// The MDNode of the scope can be omitted as well for the instructions that are
5649// part of this function. We do not do that at this point, as this might become
5650// too time consuming to do.
5651class AliasScopeTracker {
5652 SmallPtrSet<const MDNode *, 8> UsedAliasScopesAndLists;
5653 SmallPtrSet<const MDNode *, 8> UsedNoAliasScopesAndLists;
5654
5655public:
5656 void analyse(Instruction *I) {
5657 // This seems to be faster than checking 'mayReadOrWriteMemory()'.
5658 if (!I->hasMetadataOtherThanDebugLoc())
5659 return;
5660
5661 auto Track = [](Metadata *ScopeList, auto &Container) {
5662 const auto *MDScopeList = dyn_cast_or_null<MDNode>(Val: ScopeList);
5663 if (!MDScopeList || !Container.insert(MDScopeList).second)
5664 return;
5665 for (const auto &MDOperand : MDScopeList->operands())
5666 if (auto *MDScope = dyn_cast<MDNode>(Val: MDOperand))
5667 Container.insert(MDScope);
5668 };
5669
5670 Track(I->getMetadata(KindID: LLVMContext::MD_alias_scope), UsedAliasScopesAndLists);
5671 Track(I->getMetadata(KindID: LLVMContext::MD_noalias), UsedNoAliasScopesAndLists);
5672 }
5673
5674 bool isNoAliasScopeDeclDead(Instruction *Inst) {
5675 NoAliasScopeDeclInst *Decl = dyn_cast<NoAliasScopeDeclInst>(Val: Inst);
5676 if (!Decl)
5677 return false;
5678
5679 assert(Decl->use_empty() &&
5680 "llvm.experimental.noalias.scope.decl in use ?");
5681 const MDNode *MDSL = Decl->getScopeList();
5682 assert(MDSL->getNumOperands() == 1 &&
5683 "llvm.experimental.noalias.scope should refer to a single scope");
5684 auto &MDOperand = MDSL->getOperand(I: 0);
5685 if (auto *MD = dyn_cast<MDNode>(Val: MDOperand))
5686 return !UsedAliasScopesAndLists.contains(Ptr: MD) ||
5687 !UsedNoAliasScopesAndLists.contains(Ptr: MD);
5688
5689 // Not an MDNode ? throw away.
5690 return true;
5691 }
5692};
5693
5694/// Populate the IC worklist from a function, by walking it in reverse
5695/// post-order and adding all reachable code to the worklist.
5696///
5697/// This has a couple of tricks to make the code faster and more powerful. In
5698/// particular, we constant fold and DCE instructions as we go, to avoid adding
5699/// them to the worklist (this significantly speeds up instcombine on code where
5700/// many instructions are dead or constant). Additionally, if we find a branch
5701/// whose condition is a known constant, we only visit the reachable successors.
5702bool InstCombinerImpl::prepareWorklist(Function &F) {
5703 bool MadeIRChange = false;
5704 SmallPtrSet<BasicBlock *, 32> LiveBlocks;
5705 SmallVector<Instruction *, 128> InstrsForInstructionWorklist;
5706 DenseMap<Constant *, Constant *> FoldedConstants;
5707 AliasScopeTracker SeenAliasScopes;
5708
5709 auto HandleOnlyLiveSuccessor = [&](BasicBlock *BB, BasicBlock *LiveSucc) {
5710 for (BasicBlock *Succ : successors(BB))
5711 if (Succ != LiveSucc && DeadEdges.insert(V: {BB, Succ}).second)
5712 for (PHINode &PN : Succ->phis())
5713 for (Use &U : PN.incoming_values())
5714 if (PN.getIncomingBlock(U) == BB && !isa<PoisonValue>(Val: U)) {
5715 U.set(PoisonValue::get(T: PN.getType()));
5716 MadeIRChange = true;
5717 }
5718 };
5719
5720 for (BasicBlock *BB : RPOT) {
5721 if (!BB->isEntryBlock() && all_of(Range: predecessors(BB), P: [&](BasicBlock *Pred) {
5722 return DeadEdges.contains(V: {Pred, BB}) || DT.dominates(A: BB, B: Pred);
5723 })) {
5724 HandleOnlyLiveSuccessor(BB, nullptr);
5725 continue;
5726 }
5727 LiveBlocks.insert(Ptr: BB);
5728
5729 for (Instruction &Inst : llvm::make_early_inc_range(Range&: *BB)) {
5730 // ConstantProp instruction if trivially constant.
5731 if (!Inst.use_empty() &&
5732 (Inst.getNumOperands() == 0 || isa<Constant>(Val: Inst.getOperand(i: 0))))
5733 if (Constant *C = ConstantFoldInstruction(I: &Inst, DL, TLI: &TLI)) {
5734 LLVM_DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << Inst
5735 << '\n');
5736 Inst.replaceAllUsesWith(V: C);
5737 ++NumConstProp;
5738 if (isInstructionTriviallyDead(I: &Inst, TLI: &TLI))
5739 Inst.eraseFromParent();
5740 MadeIRChange = true;
5741 continue;
5742 }
5743
5744 // See if we can constant fold its operands.
5745 for (Use &U : Inst.operands()) {
5746 if (!isa<ConstantVector>(Val: U) && !isa<ConstantExpr>(Val: U))
5747 continue;
5748
5749 auto *C = cast<Constant>(Val&: U);
5750 Constant *&FoldRes = FoldedConstants[C];
5751 if (!FoldRes)
5752 FoldRes = ConstantFoldConstant(C, DL, TLI: &TLI);
5753
5754 if (FoldRes != C) {
5755 LLVM_DEBUG(dbgs() << "IC: ConstFold operand of: " << Inst
5756 << "\n Old = " << *C
5757 << "\n New = " << *FoldRes << '\n');
5758 U = FoldRes;
5759 MadeIRChange = true;
5760 }
5761 }
5762
5763 // Skip processing debug and pseudo intrinsics in InstCombine. Processing
5764 // these call instructions consumes non-trivial amount of time and
5765 // provides no value for the optimization.
5766 if (!Inst.isDebugOrPseudoInst()) {
5767 InstrsForInstructionWorklist.push_back(Elt: &Inst);
5768 SeenAliasScopes.analyse(I: &Inst);
5769 }
5770 }
5771
5772 // If this is a branch or switch on a constant, mark only the single
5773 // live successor. Otherwise assume all successors are live.
5774 Instruction *TI = BB->getTerminator();
5775 if (BranchInst *BI = dyn_cast<BranchInst>(Val: TI); BI && BI->isConditional()) {
5776 if (isa<UndefValue>(Val: BI->getCondition())) {
5777 // Branch on undef is UB.
5778 HandleOnlyLiveSuccessor(BB, nullptr);
5779 continue;
5780 }
5781 if (auto *Cond = dyn_cast<ConstantInt>(Val: BI->getCondition())) {
5782 bool CondVal = Cond->getZExtValue();
5783 HandleOnlyLiveSuccessor(BB, BI->getSuccessor(i: !CondVal));
5784 continue;
5785 }
5786 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(Val: TI)) {
5787 if (isa<UndefValue>(Val: SI->getCondition())) {
5788 // Switch on undef is UB.
5789 HandleOnlyLiveSuccessor(BB, nullptr);
5790 continue;
5791 }
5792 if (auto *Cond = dyn_cast<ConstantInt>(Val: SI->getCondition())) {
5793 HandleOnlyLiveSuccessor(BB,
5794 SI->findCaseValue(C: Cond)->getCaseSuccessor());
5795 continue;
5796 }
5797 }
5798 }
5799
5800 // Remove instructions inside unreachable blocks. This prevents the
5801 // instcombine code from having to deal with some bad special cases, and
5802 // reduces use counts of instructions.
5803 for (BasicBlock &BB : F) {
5804 if (LiveBlocks.count(Ptr: &BB))
5805 continue;
5806
5807 unsigned NumDeadInstInBB;
5808 NumDeadInstInBB = removeAllNonTerminatorAndEHPadInstructions(BB: &BB);
5809
5810 MadeIRChange |= NumDeadInstInBB != 0;
5811 NumDeadInst += NumDeadInstInBB;
5812 }
5813
5814 // Once we've found all of the instructions to add to instcombine's worklist,
5815 // add them in reverse order. This way instcombine will visit from the top
5816 // of the function down. This jives well with the way that it adds all uses
5817 // of instructions to the worklist after doing a transformation, thus avoiding
5818 // some N^2 behavior in pathological cases.
5819 Worklist.reserve(Size: InstrsForInstructionWorklist.size());
5820 for (Instruction *Inst : reverse(C&: InstrsForInstructionWorklist)) {
5821 // DCE instruction if trivially dead. As we iterate in reverse program
5822 // order here, we will clean up whole chains of dead instructions.
5823 if (isInstructionTriviallyDead(I: Inst, TLI: &TLI) ||
5824 SeenAliasScopes.isNoAliasScopeDeclDead(Inst)) {
5825 ++NumDeadInst;
5826 LLVM_DEBUG(dbgs() << "IC: DCE: " << *Inst << '\n');
5827 salvageDebugInfo(I&: *Inst);
5828 Inst->eraseFromParent();
5829 MadeIRChange = true;
5830 continue;
5831 }
5832
5833 Worklist.push(I: Inst);
5834 }
5835
5836 return MadeIRChange;
5837}
5838
5839void InstCombiner::computeBackEdges() {
5840 // Collect backedges.
5841 SmallPtrSet<BasicBlock *, 16> Visited;
5842 for (BasicBlock *BB : RPOT) {
5843 Visited.insert(Ptr: BB);
5844 for (BasicBlock *Succ : successors(BB))
5845 if (Visited.contains(Ptr: Succ))
5846 BackEdges.insert(V: {BB, Succ});
5847 }
5848 ComputedBackEdges = true;
5849}
5850
5851static bool combineInstructionsOverFunction(
5852 Function &F, InstructionWorklist &Worklist, AliasAnalysis *AA,
5853 AssumptionCache &AC, TargetLibraryInfo &TLI, TargetTransformInfo &TTI,
5854 DominatorTree &DT, OptimizationRemarkEmitter &ORE, BlockFrequencyInfo *BFI,
5855 BranchProbabilityInfo *BPI, ProfileSummaryInfo *PSI,
5856 const InstCombineOptions &Opts) {
5857 auto &DL = F.getDataLayout();
5858 bool VerifyFixpoint = Opts.VerifyFixpoint &&
5859 !F.hasFnAttribute(Kind: "instcombine-no-verify-fixpoint");
5860
5861 /// Builder - This is an IRBuilder that automatically inserts new
5862 /// instructions into the worklist when they are created.
5863 IRBuilder<TargetFolder, IRBuilderCallbackInserter> Builder(
5864 F.getContext(), TargetFolder(DL),
5865 IRBuilderCallbackInserter([&Worklist, &AC](Instruction *I) {
5866 Worklist.add(I);
5867 if (auto *Assume = dyn_cast<AssumeInst>(Val: I))
5868 AC.registerAssumption(CI: Assume);
5869 }));
5870
5871 ReversePostOrderTraversal<BasicBlock *> RPOT(&F.front());
5872
5873 // Lower dbg.declare intrinsics otherwise their value may be clobbered
5874 // by instcombiner.
5875 bool MadeIRChange = false;
5876 if (ShouldLowerDbgDeclare)
5877 MadeIRChange = LowerDbgDeclare(F);
5878
5879 // Iterate while there is work to do.
5880 unsigned Iteration = 0;
5881 while (true) {
5882 if (Iteration >= Opts.MaxIterations && !VerifyFixpoint) {
5883 LLVM_DEBUG(dbgs() << "\n\n[IC] Iteration limit #" << Opts.MaxIterations
5884 << " on " << F.getName()
5885 << " reached; stopping without verifying fixpoint\n");
5886 break;
5887 }
5888
5889 ++Iteration;
5890 ++NumWorklistIterations;
5891 LLVM_DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
5892 << F.getName() << "\n");
5893
5894 InstCombinerImpl IC(Worklist, Builder, F.hasMinSize(), AA, AC, TLI, TTI, DT,
5895 ORE, BFI, BPI, PSI, DL, RPOT);
5896 IC.MaxArraySizeForCombine = MaxArraySize;
5897 bool MadeChangeInThisIteration = IC.prepareWorklist(F);
5898 MadeChangeInThisIteration |= IC.run();
5899 if (!MadeChangeInThisIteration)
5900 break;
5901
5902 MadeIRChange = true;
5903 if (Iteration > Opts.MaxIterations) {
5904 reportFatalUsageError(
5905 reason: "Instruction Combining on " + Twine(F.getName()) +
5906 " did not reach a fixpoint after " + Twine(Opts.MaxIterations) +
5907 " iterations. " +
5908 "Use 'instcombine<no-verify-fixpoint>' or function attribute "
5909 "'instcombine-no-verify-fixpoint' to suppress this error.");
5910 }
5911 }
5912
5913 if (Iteration == 1)
5914 ++NumOneIteration;
5915 else if (Iteration == 2)
5916 ++NumTwoIterations;
5917 else if (Iteration == 3)
5918 ++NumThreeIterations;
5919 else
5920 ++NumFourOrMoreIterations;
5921
5922 return MadeIRChange;
5923}
5924
5925InstCombinePass::InstCombinePass(InstCombineOptions Opts) : Options(Opts) {}
5926
5927void InstCombinePass::printPipeline(
5928 raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
5929 static_cast<PassInfoMixin<InstCombinePass> *>(this)->printPipeline(
5930 OS, MapClassName2PassName);
5931 OS << '<';
5932 OS << "max-iterations=" << Options.MaxIterations << ";";
5933 OS << (Options.VerifyFixpoint ? "" : "no-") << "verify-fixpoint";
5934 OS << '>';
5935}
5936
5937char InstCombinePass::ID = 0;
5938
5939PreservedAnalyses InstCombinePass::run(Function &F,
5940 FunctionAnalysisManager &AM) {
5941 auto &LRT = AM.getResult<LastRunTrackingAnalysis>(IR&: F);
5942 // No changes since last InstCombine pass, exit early.
5943 if (LRT.shouldSkip(ID: &ID))
5944 return PreservedAnalyses::all();
5945
5946 auto &AC = AM.getResult<AssumptionAnalysis>(IR&: F);
5947 auto &DT = AM.getResult<DominatorTreeAnalysis>(IR&: F);
5948 auto &TLI = AM.getResult<TargetLibraryAnalysis>(IR&: F);
5949 auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(IR&: F);
5950 auto &TTI = AM.getResult<TargetIRAnalysis>(IR&: F);
5951
5952 auto *AA = &AM.getResult<AAManager>(IR&: F);
5953 auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(IR&: F);
5954 ProfileSummaryInfo *PSI =
5955 MAMProxy.getCachedResult<ProfileSummaryAnalysis>(IR&: *F.getParent());
5956 auto *BFI = (PSI && PSI->hasProfileSummary()) ?
5957 &AM.getResult<BlockFrequencyAnalysis>(IR&: F) : nullptr;
5958 auto *BPI = AM.getCachedResult<BranchProbabilityAnalysis>(IR&: F);
5959
5960 if (!combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, TTI, DT, ORE,
5961 BFI, BPI, PSI, Opts: Options)) {
5962 // No changes, all analyses are preserved.
5963 LRT.update(ID: &ID, /*Changed=*/false);
5964 return PreservedAnalyses::all();
5965 }
5966
5967 // Mark all the analyses that instcombine updates as preserved.
5968 PreservedAnalyses PA;
5969 LRT.update(ID: &ID, /*Changed=*/true);
5970 PA.preserve<LastRunTrackingAnalysis>();
5971 PA.preserveSet<CFGAnalyses>();
5972 return PA;
5973}
5974
5975void InstructionCombiningPass::getAnalysisUsage(AnalysisUsage &AU) const {
5976 AU.setPreservesCFG();
5977 AU.addRequired<AAResultsWrapperPass>();
5978 AU.addRequired<AssumptionCacheTracker>();
5979 AU.addRequired<TargetLibraryInfoWrapperPass>();
5980 AU.addRequired<TargetTransformInfoWrapperPass>();
5981 AU.addRequired<DominatorTreeWrapperPass>();
5982 AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
5983 AU.addPreserved<DominatorTreeWrapperPass>();
5984 AU.addPreserved<AAResultsWrapperPass>();
5985 AU.addPreserved<BasicAAWrapperPass>();
5986 AU.addPreserved<GlobalsAAWrapperPass>();
5987 AU.addRequired<ProfileSummaryInfoWrapperPass>();
5988 LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AU);
5989}
5990
5991bool InstructionCombiningPass::runOnFunction(Function &F) {
5992 if (skipFunction(F))
5993 return false;
5994
5995 // Required analyses.
5996 auto AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
5997 auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
5998 auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
5999 auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
6000 auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
6001 auto &ORE = getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
6002
6003 // Optional analyses.
6004 ProfileSummaryInfo *PSI =
6005 &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
6006 BlockFrequencyInfo *BFI =
6007 (PSI && PSI->hasProfileSummary()) ?
6008 &getAnalysis<LazyBlockFrequencyInfoPass>().getBFI() :
6009 nullptr;
6010 BranchProbabilityInfo *BPI = nullptr;
6011 if (auto *WrapperPass =
6012 getAnalysisIfAvailable<BranchProbabilityInfoWrapperPass>())
6013 BPI = &WrapperPass->getBPI();
6014
6015 return combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, TTI, DT, ORE,
6016 BFI, BPI, PSI, Opts: InstCombineOptions());
6017}
6018
6019char InstructionCombiningPass::ID = 0;
6020
6021InstructionCombiningPass::InstructionCombiningPass() : FunctionPass(ID) {
6022 initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
6023}
6024
6025INITIALIZE_PASS_BEGIN(InstructionCombiningPass, "instcombine",
6026 "Combine redundant instructions", false, false)
6027INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
6028INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
6029INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
6030INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
6031INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
6032INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
6033INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
6034INITIALIZE_PASS_DEPENDENCY(LazyBlockFrequencyInfoPass)
6035INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
6036INITIALIZE_PASS_END(InstructionCombiningPass, "instcombine",
6037 "Combine redundant instructions", false, false)
6038
6039// Initialization Routines
6040void llvm::initializeInstCombine(PassRegistry &Registry) {
6041 initializeInstructionCombiningPassPass(Registry);
6042}
6043
6044FunctionPass *llvm::createInstructionCombiningPass() {
6045 return new InstructionCombiningPass();
6046}
6047