InstCombineInternal.h revision 309124 
1//===- InstCombineInternal.h - InstCombine pass internals -------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9/// \file
10///
11/// This file provides internal interfaces used to implement the InstCombine.
12///
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
16#define LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H
17
18#include "llvm/Analysis/AliasAnalysis.h"
19#include "llvm/Analysis/AssumptionCache.h"
20#include "llvm/Analysis/LoopInfo.h"
21#include "llvm/Analysis/TargetFolder.h"
22#include "llvm/Analysis/ValueTracking.h"
23#include "llvm/IR/Dominators.h"
24#include "llvm/IR/IRBuilder.h"
25#include "llvm/IR/InstVisitor.h"
26#include "llvm/IR/IntrinsicInst.h"
27#include "llvm/IR/Operator.h"
28#include "llvm/IR/PatternMatch.h"
29#include "llvm/Pass.h"
30#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
31
32#define DEBUG_TYPE "instcombine"
33
34namespace llvm {
35class CallSite;
36class DataLayout;
37class DominatorTree;
38class TargetLibraryInfo;
39class DbgDeclareInst;
40class MemIntrinsic;
41class MemSetInst;
42
43/// \brief Assign a complexity or rank value to LLVM Values.
44///
45/// This routine maps IR values to various complexity ranks:
46///   0 -> undef
47///   1 -> Constants
48///   2 -> Other non-instructions
49///   3 -> Arguments
50///   3 -> Unary operations
51///   4 -> Other instructions
52static inline unsigned getComplexity(Value *V) {
53  if (isa<Instruction>(V)) {
54    if (BinaryOperator::isNeg(V) || BinaryOperator::isFNeg(V) ||
55        BinaryOperator::isNot(V))
56      return 3;
57    return 4;
58  }
59  if (isa<Argument>(V))
60    return 3;
61  return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
62}
63
64/// \brief Add one to a Constant
65static inline Constant *AddOne(Constant *C) {
66  return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
67}
68/// \brief Subtract one from a Constant
69static inline Constant *SubOne(Constant *C) {
70  return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
71}
72
73/// \brief Return true if the specified value is free to invert (apply ~ to).
74/// This happens in cases where the ~ can be eliminated.  If WillInvertAllUses
75/// is true, work under the assumption that the caller intends to remove all
76/// uses of V and only keep uses of ~V.
77///
78static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) {
79  // ~(~(X)) -> X.
80  if (BinaryOperator::isNot(V))
81    return true;
82
83  // Constants can be considered to be not'ed values.
84  if (isa<ConstantInt>(V))
85    return true;
86
87  // Compares can be inverted if all of their uses are being modified to use the
88  // ~V.
89  if (isa<CmpInst>(V))
90    return WillInvertAllUses;
91
92  // If `V` is of the form `A + Constant` then `-1 - V` can be folded into `(-1
93  // - Constant) - A` if we are willing to invert all of the uses.
94  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
95    if (BO->getOpcode() == Instruction::Add ||
96        BO->getOpcode() == Instruction::Sub)
97      if (isa<Constant>(BO->getOperand(0)) || isa<Constant>(BO->getOperand(1)))
98        return WillInvertAllUses;
99
100  return false;
101}
102
103
104/// \brief Specific patterns of overflow check idioms that we match.
105enum OverflowCheckFlavor {
106  OCF_UNSIGNED_ADD,
107  OCF_SIGNED_ADD,
108  OCF_UNSIGNED_SUB,
109  OCF_SIGNED_SUB,
110  OCF_UNSIGNED_MUL,
111  OCF_SIGNED_MUL,
112
113  OCF_INVALID
114};
115
116/// \brief Returns the OverflowCheckFlavor corresponding to a overflow_with_op
117/// intrinsic.
118static inline OverflowCheckFlavor
119IntrinsicIDToOverflowCheckFlavor(unsigned ID) {
120  switch (ID) {
121  default:
122    return OCF_INVALID;
123  case Intrinsic::uadd_with_overflow:
124    return OCF_UNSIGNED_ADD;
125  case Intrinsic::sadd_with_overflow:
126    return OCF_SIGNED_ADD;
127  case Intrinsic::usub_with_overflow:
128    return OCF_UNSIGNED_SUB;
129  case Intrinsic::ssub_with_overflow:
130    return OCF_SIGNED_SUB;
131  case Intrinsic::umul_with_overflow:
132    return OCF_UNSIGNED_MUL;
133  case Intrinsic::smul_with_overflow:
134    return OCF_SIGNED_MUL;
135  }
136}
137
138/// \brief An IRBuilder inserter that adds new instructions to the instcombine
139/// worklist.
140class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter
141    : public IRBuilderDefaultInserter {
142  InstCombineWorklist &Worklist;
143  AssumptionCache *AC;
144
145public:
146  InstCombineIRInserter(InstCombineWorklist &WL, AssumptionCache *AC)
147      : Worklist(WL), AC(AC) {}
148
149  void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
150                    BasicBlock::iterator InsertPt) const {
151    IRBuilderDefaultInserter::InsertHelper(I, Name, BB, InsertPt);
152    Worklist.Add(I);
153
154    using namespace llvm::PatternMatch;
155    if (match(I, m_Intrinsic<Intrinsic::assume>()))
156      AC->registerAssumption(cast<CallInst>(I));
157  }
158};
159
160/// \brief The core instruction combiner logic.
161///
162/// This class provides both the logic to recursively visit instructions and
163/// combine them, as well as the pass infrastructure for running this as part
164/// of the LLVM pass pipeline.
165class LLVM_LIBRARY_VISIBILITY InstCombiner
166    : public InstVisitor<InstCombiner, Instruction *> {
167  // FIXME: These members shouldn't be public.
168public:
169  /// \brief A worklist of the instructions that need to be simplified.
170  InstCombineWorklist &Worklist;
171
172  /// \brief An IRBuilder that automatically inserts new instructions into the
173  /// worklist.
174  typedef IRBuilder<TargetFolder, InstCombineIRInserter> BuilderTy;
175  BuilderTy *Builder;
176
177private:
178  // Mode in which we are running the combiner.
179  const bool MinimizeSize;
180  /// Enable combines that trigger rarely but are costly in compiletime.
181  const bool ExpensiveCombines;
182
183  AliasAnalysis *AA;
184
185  // Required analyses.
186  // FIXME: These can never be null and should be references.
187  AssumptionCache *AC;
188  TargetLibraryInfo *TLI;
189  DominatorTree *DT;
190  const DataLayout &DL;
191
192  // Optional analyses. When non-null, these can both be used to do better
193  // combining and will be updated to reflect any changes.
194  LoopInfo *LI;
195
196  bool MadeIRChange;
197
198public:
199  InstCombiner(InstCombineWorklist &Worklist, BuilderTy *Builder,
200               bool MinimizeSize, bool ExpensiveCombines, AliasAnalysis *AA,
201               AssumptionCache *AC, TargetLibraryInfo *TLI,
202               DominatorTree *DT, const DataLayout &DL, LoopInfo *LI)
203      : Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize),
204        ExpensiveCombines(ExpensiveCombines), AA(AA), AC(AC), TLI(TLI), DT(DT),
205        DL(DL), LI(LI), MadeIRChange(false) {}
206
207  /// \brief Run the combiner over the entire worklist until it is empty.
208  ///
209  /// \returns true if the IR is changed.
210  bool run();
211
212  AssumptionCache *getAssumptionCache() const { return AC; }
213
214  const DataLayout &getDataLayout() const { return DL; }
215
216  DominatorTree *getDominatorTree() const { return DT; }
217
218  LoopInfo *getLoopInfo() const { return LI; }
219
220  TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; }
221
222  // Visitation implementation - Implement instruction combining for different
223  // instruction types.  The semantics are as follows:
224  // Return Value:
225  //    null        - No change was made
226  //     I          - Change was made, I is still valid, I may be dead though
227  //   otherwise    - Change was made, replace I with returned instruction
228  //
229  Instruction *visitAdd(BinaryOperator &I);
230  Instruction *visitFAdd(BinaryOperator &I);
231  Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty);
232  Instruction *visitSub(BinaryOperator &I);
233  Instruction *visitFSub(BinaryOperator &I);
234  Instruction *visitMul(BinaryOperator &I);
235  Value *foldFMulConst(Instruction *FMulOrDiv, Constant *C,
236                       Instruction *InsertBefore);
237  Instruction *visitFMul(BinaryOperator &I);
238  Instruction *visitURem(BinaryOperator &I);
239  Instruction *visitSRem(BinaryOperator &I);
240  Instruction *visitFRem(BinaryOperator &I);
241  bool SimplifyDivRemOfSelect(BinaryOperator &I);
242  Instruction *commonRemTransforms(BinaryOperator &I);
243  Instruction *commonIRemTransforms(BinaryOperator &I);
244  Instruction *commonDivTransforms(BinaryOperator &I);
245  Instruction *commonIDivTransforms(BinaryOperator &I);
246  Instruction *visitUDiv(BinaryOperator &I);
247  Instruction *visitSDiv(BinaryOperator &I);
248  Instruction *visitFDiv(BinaryOperator &I);
249  Value *simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted);
250  Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
251  Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
252  Instruction *visitAnd(BinaryOperator &I);
253  Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI);
254  Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
255  Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A,
256                                   Value *B, Value *C);
257  Instruction *FoldXorWithConstants(BinaryOperator &I, Value *Op, Value *A,
258                                    Value *B, Value *C);
259  Instruction *visitOr(BinaryOperator &I);
260  Instruction *visitXor(BinaryOperator &I);
261  Instruction *visitShl(BinaryOperator &I);
262  Instruction *visitAShr(BinaryOperator &I);
263  Instruction *visitLShr(BinaryOperator &I);
264  Instruction *commonShiftTransforms(BinaryOperator &I);
265  Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
266                                    Constant *RHSC);
267  Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
268                                            GlobalVariable *GV, CmpInst &ICI,
269                                            ConstantInt *AndCst = nullptr);
270  Instruction *visitFCmpInst(FCmpInst &I);
271  Instruction *visitICmpInst(ICmpInst &I);
272  Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
273  Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, Instruction *LHS,
274                                              ConstantInt *RHS);
275  Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
276                              ConstantInt *DivRHS);
277  Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI,
278                              ConstantInt *DivRHS);
279  Instruction *FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,
280                                 ConstantInt *CI1, ConstantInt *CI2);
281  Instruction *FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A,
282                                 ConstantInt *CI1, ConstantInt *CI2);
283  Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI,
284                                ICmpInst::Predicate Pred);
285  Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
286                           ICmpInst::Predicate Cond, Instruction &I);
287  Instruction *FoldAllocaCmp(ICmpInst &ICI, AllocaInst *Alloca, Value *Other);
288  Instruction *FoldShiftByConstant(Value *Op0, Constant *Op1,
289                                   BinaryOperator &I);
290  Instruction *commonCastTransforms(CastInst &CI);
291  Instruction *commonPointerCastTransforms(CastInst &CI);
292  Instruction *visitTrunc(TruncInst &CI);
293  Instruction *visitZExt(ZExtInst &CI);
294  Instruction *visitSExt(SExtInst &CI);
295  Instruction *visitFPTrunc(FPTruncInst &CI);
296  Instruction *visitFPExt(CastInst &CI);
297  Instruction *visitFPToUI(FPToUIInst &FI);
298  Instruction *visitFPToSI(FPToSIInst &FI);
299  Instruction *visitUIToFP(CastInst &CI);
300  Instruction *visitSIToFP(CastInst &CI);
301  Instruction *visitPtrToInt(PtrToIntInst &CI);
302  Instruction *visitIntToPtr(IntToPtrInst &CI);
303  Instruction *visitBitCast(BitCastInst &CI);
304  Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
305  Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI);
306  Instruction *FoldSelectIntoOp(SelectInst &SI, Value *, Value *);
307  Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
308                            Value *A, Value *B, Instruction &Outer,
309                            SelectPatternFlavor SPF2, Value *C);
310  Instruction *FoldItoFPtoI(Instruction &FI);
311  Instruction *visitSelectInst(SelectInst &SI);
312  Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
313  Instruction *visitCallInst(CallInst &CI);
314  Instruction *visitInvokeInst(InvokeInst &II);
315
316  Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
317  Instruction *visitPHINode(PHINode &PN);
318  Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
319  Instruction *visitAllocaInst(AllocaInst &AI);
320  Instruction *visitAllocSite(Instruction &FI);
321  Instruction *visitFree(CallInst &FI);
322  Instruction *visitLoadInst(LoadInst &LI);
323  Instruction *visitStoreInst(StoreInst &SI);
324  Instruction *visitBranchInst(BranchInst &BI);
325  Instruction *visitSwitchInst(SwitchInst &SI);
326  Instruction *visitReturnInst(ReturnInst &RI);
327  Instruction *visitInsertValueInst(InsertValueInst &IV);
328  Instruction *visitInsertElementInst(InsertElementInst &IE);
329  Instruction *visitExtractElementInst(ExtractElementInst &EI);
330  Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
331  Instruction *visitExtractValueInst(ExtractValueInst &EV);
332  Instruction *visitLandingPadInst(LandingPadInst &LI);
333  Instruction *visitVAStartInst(VAStartInst &I);
334  Instruction *visitVACopyInst(VACopyInst &I);
335
336  // visitInstruction - Specify what to return for unhandled instructions...
337  Instruction *visitInstruction(Instruction &I) { return nullptr; }
338
339  // True when DB dominates all uses of DI execpt UI.
340  // UI must be in the same block as DI.
341  // The routine checks that the DI parent and DB are different.
342  bool dominatesAllUses(const Instruction *DI, const Instruction *UI,
343                        const BasicBlock *DB) const;
344
345  // Replace select with select operand SIOpd in SI-ICmp sequence when possible
346  bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp,
347                                 const unsigned SIOpd);
348
349private:
350  bool ShouldChangeType(unsigned FromBitWidth, unsigned ToBitWidth) const;
351  bool ShouldChangeType(Type *From, Type *To) const;
352  Value *dyn_castNegVal(Value *V) const;
353  Value *dyn_castFNegVal(Value *V, bool NoSignedZero = false) const;
354  Type *FindElementAtOffset(PointerType *PtrTy, int64_t Offset,
355                            SmallVectorImpl<Value *> &NewIndices);
356  Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI);
357
358  /// \brief Classify whether a cast is worth optimizing.
359  ///
360  /// Returns true if the cast from "V to Ty" actually results in any code
361  /// being generated and is interesting to optimize out. If the cast can be
362  /// eliminated by some other simple transformation, we prefer to do the
363  /// simplification first.
364  bool ShouldOptimizeCast(Instruction::CastOps opcode, const Value *V,
365                          Type *Ty);
366
367  /// \brief Try to optimize a sequence of instructions checking if an operation
368  /// on LHS and RHS overflows.
369  ///
370  /// If this overflow check is done via one of the overflow check intrinsics,
371  /// then CtxI has to be the call instruction calling that intrinsic.  If this
372  /// overflow check is done by arithmetic followed by a compare, then CtxI has
373  /// to be the arithmetic instruction.
374  ///
375  /// If a simplification is possible, stores the simplified result of the
376  /// operation in OperationResult and result of the overflow check in
377  /// OverflowResult, and return true.  If no simplification is possible,
378  /// returns false.
379  bool OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS, Value *RHS,
380                             Instruction &CtxI, Value *&OperationResult,
381                             Constant *&OverflowResult);
382
383  Instruction *visitCallSite(CallSite CS);
384  Instruction *tryOptimizeCall(CallInst *CI);
385  bool transformConstExprCastCall(CallSite CS);
386  Instruction *transformCallThroughTrampoline(CallSite CS,
387                                              IntrinsicInst *Tramp);
388  Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
389                                 bool DoXform = true);
390  Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI);
391  bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS, Instruction &CxtI);
392  bool WillNotOverflowSignedSub(Value *LHS, Value *RHS, Instruction &CxtI);
393  bool WillNotOverflowUnsignedSub(Value *LHS, Value *RHS, Instruction &CxtI);
394  bool WillNotOverflowSignedMul(Value *LHS, Value *RHS, Instruction &CxtI);
395  Value *EmitGEPOffset(User *GEP);
396  Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
397  Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
398  Instruction *foldCastedBitwiseLogic(BinaryOperator &I);
399
400public:
401  /// \brief Inserts an instruction \p New before instruction \p Old
402  ///
403  /// Also adds the new instruction to the worklist and returns \p New so that
404  /// it is suitable for use as the return from the visitation patterns.
405  Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
406    assert(New && !New->getParent() &&
407           "New instruction already inserted into a basic block!");
408    BasicBlock *BB = Old.getParent();
409    BB->getInstList().insert(Old.getIterator(), New); // Insert inst
410    Worklist.Add(New);
411    return New;
412  }
413
414  /// \brief Same as InsertNewInstBefore, but also sets the debug loc.
415  Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) {
416    New->setDebugLoc(Old.getDebugLoc());
417    return InsertNewInstBefore(New, Old);
418  }
419
420  /// \brief A combiner-aware RAUW-like routine.
421  ///
422  /// This method is to be used when an instruction is found to be dead,
423  /// replaceable with another preexisting expression. Here we add all uses of
424  /// I to the worklist, replace all uses of I with the new value, then return
425  /// I, so that the inst combiner will know that I was modified.
426  Instruction *replaceInstUsesWith(Instruction &I, Value *V) {
427    // If there are no uses to replace, then we return nullptr to indicate that
428    // no changes were made to the program.
429    if (I.use_empty()) return nullptr;
430
431    Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
432
433    // If we are replacing the instruction with itself, this must be in a
434    // segment of unreachable code, so just clobber the instruction.
435    if (&I == V)
436      V = UndefValue::get(I.getType());
437
438    DEBUG(dbgs() << "IC: Replacing " << I << "\n"
439                 << "    with " << *V << '\n');
440
441    I.replaceAllUsesWith(V);
442    return &I;
443  }
444
445  /// Creates a result tuple for an overflow intrinsic \p II with a given
446  /// \p Result and a constant \p Overflow value.
447  Instruction *CreateOverflowTuple(IntrinsicInst *II, Value *Result,
448                                   Constant *Overflow) {
449    Constant *V[] = {UndefValue::get(Result->getType()), Overflow};
450    StructType *ST = cast<StructType>(II->getType());
451    Constant *Struct = ConstantStruct::get(ST, V);
452    return InsertValueInst::Create(Struct, Result, 0);
453  }
454
455  /// \brief Combiner aware instruction erasure.
456  ///
457  /// When dealing with an instruction that has side effects or produces a void
458  /// value, we can't rely on DCE to delete the instruction. Instead, visit
459  /// methods should return the value returned by this function.
460  Instruction *eraseInstFromFunction(Instruction &I) {
461    DEBUG(dbgs() << "IC: ERASE " << I << '\n');
462
463    assert(I.use_empty() && "Cannot erase instruction that is used!");
464    // Make sure that we reprocess all operands now that we reduced their
465    // use counts.
466    if (I.getNumOperands() < 8) {
467      for (Use &Operand : I.operands())
468        if (auto *Inst = dyn_cast<Instruction>(Operand))
469          Worklist.Add(Inst);
470    }
471    Worklist.Remove(&I);
472    I.eraseFromParent();
473    MadeIRChange = true;
474    return nullptr; // Don't do anything with FI
475  }
476
477  void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
478                        unsigned Depth, Instruction *CxtI) const {
479    return llvm::computeKnownBits(V, KnownZero, KnownOne, DL, Depth, AC, CxtI,
480                                  DT);
481  }
482
483  bool MaskedValueIsZero(Value *V, const APInt &Mask, unsigned Depth = 0,
484                         Instruction *CxtI = nullptr) const {
485    return llvm::MaskedValueIsZero(V, Mask, DL, Depth, AC, CxtI, DT);
486  }
487  unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0,
488                              Instruction *CxtI = nullptr) const {
489    return llvm::ComputeNumSignBits(Op, DL, Depth, AC, CxtI, DT);
490  }
491  void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne,
492                      unsigned Depth = 0, Instruction *CxtI = nullptr) const {
493    return llvm::ComputeSignBit(V, KnownZero, KnownOne, DL, Depth, AC, CxtI,
494                                DT);
495  }
496  OverflowResult computeOverflowForUnsignedMul(Value *LHS, Value *RHS,
497                                               const Instruction *CxtI) {
498    return llvm::computeOverflowForUnsignedMul(LHS, RHS, DL, AC, CxtI, DT);
499  }
500  OverflowResult computeOverflowForUnsignedAdd(Value *LHS, Value *RHS,
501                                               const Instruction *CxtI) {
502    return llvm::computeOverflowForUnsignedAdd(LHS, RHS, DL, AC, CxtI, DT);
503  }
504
505private:
506  /// \brief Performs a few simplifications for operators which are associative
507  /// or commutative.
508  bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
509
510  /// \brief Tries to simplify binary operations which some other binary
511  /// operation distributes over.
512  ///
513  /// It does this by either by factorizing out common terms (eg "(A*B)+(A*C)"
514  /// -> "A*(B+C)") or expanding out if this results in simplifications (eg: "A
515  /// & (B | C) -> (A&B) | (A&C)" if this is a win).  Returns the simplified
516  /// value, or null if it didn't simplify.
517  Value *SimplifyUsingDistributiveLaws(BinaryOperator &I);
518
519  /// \brief Attempts to replace V with a simpler value based on the demanded
520  /// bits.
521  Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, APInt &KnownZero,
522                                 APInt &KnownOne, unsigned Depth,
523                                 Instruction *CxtI);
524  bool SimplifyDemandedBits(Use &U, const APInt &DemandedMask, APInt &KnownZero,
525                            APInt &KnownOne, unsigned Depth = 0);
526  /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded
527  /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence.
528  Value *SimplifyShrShlDemandedBits(Instruction *Lsr, Instruction *Sftl,
529                                    const APInt &DemandedMask, APInt &KnownZero,
530                                    APInt &KnownOne);
531
532  /// \brief Tries to simplify operands to an integer instruction based on its
533  /// demanded bits.
534  bool SimplifyDemandedInstructionBits(Instruction &Inst);
535
536  Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
537                                    APInt &UndefElts, unsigned Depth = 0);
538
539  Value *SimplifyVectorOp(BinaryOperator &Inst);
540  Value *SimplifyBSwap(BinaryOperator &Inst);
541
542  // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
543  // which has a PHI node as operand #0, see if we can fold the instruction
544  // into the PHI (which is only possible if all operands to the PHI are
545  // constants).
546  //
547  Instruction *FoldOpIntoPhi(Instruction &I);
548
549  /// \brief Try to rotate an operation below a PHI node, using PHI nodes for
550  /// its operands.
551  Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
552  Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
553  Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
554  Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
555  Instruction *FoldPHIArgZextsIntoPHI(PHINode &PN);
556
557  Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
558                        ConstantInt *AndRHS, BinaryOperator &TheAnd);
559
560  Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
561                            bool isSub, Instruction &I);
562  Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, bool isSigned,
563                         bool Inside);
564  Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
565  Instruction *MatchBSwap(BinaryOperator &I);
566  bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
567  Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
568  Instruction *SimplifyMemSet(MemSetInst *MI);
569
570  Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
571
572  /// \brief Returns a value X such that Val = X * Scale, or null if none.
573  ///
574  /// If the multiplication is known not to overflow then NoSignedWrap is set.
575  Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap);
576};
577
578} // end namespace llvm.
579
580#undef DEBUG_TYPE
581
582#endif
583