InstCombineInternal.h revision 0c7f116bb6950ef819323d855415b2f2b0aad987 
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/AssumptionCache.h"
19#include "llvm/Analysis/LoopInfo.h"
20#include "llvm/Analysis/TargetFolder.h"
21#include "llvm/Analysis/ValueTracking.h"
22#include "llvm/IR/Dominators.h"
23#include "llvm/IR/IRBuilder.h"
24#include "llvm/IR/InstVisitor.h"
25#include "llvm/IR/IntrinsicInst.h"
26#include "llvm/IR/Operator.h"
27#include "llvm/IR/PatternMatch.h"
28#include "llvm/Pass.h"
29#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
30
31#define DEBUG_TYPE "instcombine"
32
33namespace llvm {
34class CallSite;
35class DataLayout;
36class DominatorTree;
37class TargetLibraryInfo;
38class DbgDeclareInst;
39class MemIntrinsic;
40class MemSetInst;
41
42/// \brief Specific patterns of select instructions we can match.
43enum SelectPatternFlavor {
44  SPF_UNKNOWN = 0,
45  SPF_SMIN,
46  SPF_UMIN,
47  SPF_SMAX,
48  SPF_UMAX,
49  SPF_ABS,
50  SPF_NABS
51};
52
53/// \brief Assign a complexity or rank value to LLVM Values.
54///
55/// This routine maps IR values to various complexity ranks:
56///   0 -> undef
57///   1 -> Constants
58///   2 -> Other non-instructions
59///   3 -> Arguments
60///   3 -> Unary operations
61///   4 -> Other instructions
62static inline unsigned getComplexity(Value *V) {
63  if (isa<Instruction>(V)) {
64    if (BinaryOperator::isNeg(V) || BinaryOperator::isFNeg(V) ||
65        BinaryOperator::isNot(V))
66      return 3;
67    return 4;
68  }
69  if (isa<Argument>(V))
70    return 3;
71  return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
72}
73
74/// \brief Add one to a Constant
75static inline Constant *AddOne(Constant *C) {
76  return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
77}
78/// \brief Subtract one from a Constant
79static inline Constant *SubOne(Constant *C) {
80  return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
81}
82
83/// \brief Return true if the specified value is free to invert (apply ~ to).
84/// This happens in cases where the ~ can be eliminated.  If WillInvertAllUses
85/// is true, work under the assumption that the caller intends to remove all
86/// uses of V and only keep uses of ~V.
87///
88static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) {
89  // ~(~(X)) -> X.
90  if (BinaryOperator::isNot(V))
91    return true;
92
93  // Constants can be considered to be not'ed values.
94  if (isa<ConstantInt>(V))
95    return true;
96
97  // Compares can be inverted if all of their uses are being modified to use the
98  // ~V.
99  if (isa<CmpInst>(V))
100    return WillInvertAllUses;
101
102  // If `V` is of the form `A + Constant` then `-1 - V` can be folded into `(-1
103  // - Constant) - A` if we are willing to invert all of the uses.
104  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
105    if (BO->getOpcode() == Instruction::Add ||
106        BO->getOpcode() == Instruction::Sub)
107      if (isa<Constant>(BO->getOperand(0)) || isa<Constant>(BO->getOperand(1)))
108        return WillInvertAllUses;
109
110  return false;
111}
112
113
114/// \brief Specific patterns of overflow check idioms that we match.
115enum OverflowCheckFlavor {
116  OCF_UNSIGNED_ADD,
117  OCF_SIGNED_ADD,
118  OCF_UNSIGNED_SUB,
119  OCF_SIGNED_SUB,
120  OCF_UNSIGNED_MUL,
121  OCF_SIGNED_MUL,
122
123  OCF_INVALID
124};
125
126/// \brief Returns the OverflowCheckFlavor corresponding to a overflow_with_op
127/// intrinsic.
128static inline OverflowCheckFlavor
129IntrinsicIDToOverflowCheckFlavor(unsigned ID) {
130  switch (ID) {
131  default:
132    return OCF_INVALID;
133  case Intrinsic::uadd_with_overflow:
134    return OCF_UNSIGNED_ADD;
135  case Intrinsic::sadd_with_overflow:
136    return OCF_SIGNED_ADD;
137  case Intrinsic::usub_with_overflow:
138    return OCF_UNSIGNED_SUB;
139  case Intrinsic::ssub_with_overflow:
140    return OCF_SIGNED_SUB;
141  case Intrinsic::umul_with_overflow:
142    return OCF_UNSIGNED_MUL;
143  case Intrinsic::smul_with_overflow:
144    return OCF_SIGNED_MUL;
145  }
146}
147
148/// \brief An IRBuilder inserter that adds new instructions to the instcombine
149/// worklist.
150class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter
151    : public IRBuilderDefaultInserter<true> {
152  InstCombineWorklist &Worklist;
153  AssumptionCache *AC;
154
155public:
156  InstCombineIRInserter(InstCombineWorklist &WL, AssumptionCache *AC)
157      : Worklist(WL), AC(AC) {}
158
159  void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
160                    BasicBlock::iterator InsertPt) const {
161    IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
162    Worklist.Add(I);
163
164    using namespace llvm::PatternMatch;
165    if (match(I, m_Intrinsic<Intrinsic::assume>()))
166      AC->registerAssumption(cast<CallInst>(I));
167  }
168};
169
170/// \brief The core instruction combiner logic.
171///
172/// This class provides both the logic to recursively visit instructions and
173/// combine them, as well as the pass infrastructure for running this as part
174/// of the LLVM pass pipeline.
175class LLVM_LIBRARY_VISIBILITY InstCombiner
176    : public InstVisitor<InstCombiner, Instruction *> {
177  // FIXME: These members shouldn't be public.
178public:
179  /// \brief A worklist of the instructions that need to be simplified.
180  InstCombineWorklist &Worklist;
181
182  /// \brief An IRBuilder that automatically inserts new instructions into the
183  /// worklist.
184  typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
185  BuilderTy *Builder;
186
187private:
188  // Mode in which we are running the combiner.
189  const bool MinimizeSize;
190
191  // Required analyses.
192  // FIXME: These can never be null and should be references.
193  AssumptionCache *AC;
194  TargetLibraryInfo *TLI;
195  DominatorTree *DT;
196  const DataLayout &DL;
197
198  // Optional analyses. When non-null, these can both be used to do better
199  // combining and will be updated to reflect any changes.
200  LoopInfo *LI;
201
202  bool MadeIRChange;
203
204public:
205  InstCombiner(InstCombineWorklist &Worklist, BuilderTy *Builder,
206               bool MinimizeSize, AssumptionCache *AC, TargetLibraryInfo *TLI,
207               DominatorTree *DT, const DataLayout &DL, LoopInfo *LI)
208      : Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize),
209        AC(AC), TLI(TLI), DT(DT), DL(DL), LI(LI), MadeIRChange(false) {}
210
211  /// \brief Run the combiner over the entire worklist until it is empty.
212  ///
213  /// \returns true if the IR is changed.
214  bool run();
215
216  AssumptionCache *getAssumptionCache() const { return AC; }
217
218  const DataLayout &getDataLayout() const { return DL; }
219
220  DominatorTree *getDominatorTree() const { return DT; }
221
222  LoopInfo *getLoopInfo() const { return LI; }
223
224  TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; }
225
226  // Visitation implementation - Implement instruction combining for different
227  // instruction types.  The semantics are as follows:
228  // Return Value:
229  //    null        - No change was made
230  //     I          - Change was made, I is still valid, I may be dead though
231  //   otherwise    - Change was made, replace I with returned instruction
232  //
233  Instruction *visitAdd(BinaryOperator &I);
234  Instruction *visitFAdd(BinaryOperator &I);
235  Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty);
236  Instruction *visitSub(BinaryOperator &I);
237  Instruction *visitFSub(BinaryOperator &I);
238  Instruction *visitMul(BinaryOperator &I);
239  Value *foldFMulConst(Instruction *FMulOrDiv, Constant *C,
240                       Instruction *InsertBefore);
241  Instruction *visitFMul(BinaryOperator &I);
242  Instruction *visitURem(BinaryOperator &I);
243  Instruction *visitSRem(BinaryOperator &I);
244  Instruction *visitFRem(BinaryOperator &I);
245  bool SimplifyDivRemOfSelect(BinaryOperator &I);
246  Instruction *commonRemTransforms(BinaryOperator &I);
247  Instruction *commonIRemTransforms(BinaryOperator &I);
248  Instruction *commonDivTransforms(BinaryOperator &I);
249  Instruction *commonIDivTransforms(BinaryOperator &I);
250  Instruction *visitUDiv(BinaryOperator &I);
251  Instruction *visitSDiv(BinaryOperator &I);
252  Instruction *visitFDiv(BinaryOperator &I);
253  Value *simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted);
254  Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
255  Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
256  Instruction *visitAnd(BinaryOperator &I);
257  Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI);
258  Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
259  Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A,
260                                   Value *B, Value *C);
261  Instruction *FoldXorWithConstants(BinaryOperator &I, Value *Op, Value *A,
262                                    Value *B, Value *C);
263  Instruction *visitOr(BinaryOperator &I);
264  Instruction *visitXor(BinaryOperator &I);
265  Instruction *visitShl(BinaryOperator &I);
266  Instruction *visitAShr(BinaryOperator &I);
267  Instruction *visitLShr(BinaryOperator &I);
268  Instruction *commonShiftTransforms(BinaryOperator &I);
269  Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
270                                    Constant *RHSC);
271  Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
272                                            GlobalVariable *GV, CmpInst &ICI,
273                                            ConstantInt *AndCst = nullptr);
274  Instruction *visitFCmpInst(FCmpInst &I);
275  Instruction *visitICmpInst(ICmpInst &I);
276  Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
277  Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, Instruction *LHS,
278                                              ConstantInt *RHS);
279  Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
280                              ConstantInt *DivRHS);
281  Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI,
282                              ConstantInt *DivRHS);
283  Instruction *FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,
284                                 ConstantInt *CI1, ConstantInt *CI2);
285  Instruction *FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A,
286                                 ConstantInt *CI1, ConstantInt *CI2);
287  Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI,
288                                ICmpInst::Predicate Pred);
289  Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
290                           ICmpInst::Predicate Cond, Instruction &I);
291  Instruction *FoldShiftByConstant(Value *Op0, Constant *Op1,
292                                   BinaryOperator &I);
293  Instruction *commonCastTransforms(CastInst &CI);
294  Instruction *commonPointerCastTransforms(CastInst &CI);
295  Instruction *visitTrunc(TruncInst &CI);
296  Instruction *visitZExt(ZExtInst &CI);
297  Instruction *visitSExt(SExtInst &CI);
298  Instruction *visitFPTrunc(FPTruncInst &CI);
299  Instruction *visitFPExt(CastInst &CI);
300  Instruction *visitFPToUI(FPToUIInst &FI);
301  Instruction *visitFPToSI(FPToSIInst &FI);
302  Instruction *visitUIToFP(CastInst &CI);
303  Instruction *visitSIToFP(CastInst &CI);
304  Instruction *visitPtrToInt(PtrToIntInst &CI);
305  Instruction *visitIntToPtr(IntToPtrInst &CI);
306  Instruction *visitBitCast(BitCastInst &CI);
307  Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
308  Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI);
309  Instruction *FoldSelectIntoOp(SelectInst &SI, Value *, Value *);
310  Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
311                            Value *A, Value *B, Instruction &Outer,
312                            SelectPatternFlavor SPF2, Value *C);
313  Instruction *FoldItoFPtoI(Instruction &FI);
314  Instruction *visitSelectInst(SelectInst &SI);
315  Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
316  Instruction *visitCallInst(CallInst &CI);
317  Instruction *visitInvokeInst(InvokeInst &II);
318
319  Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
320  Instruction *visitPHINode(PHINode &PN);
321  Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
322  Instruction *visitAllocaInst(AllocaInst &AI);
323  Instruction *visitAllocSite(Instruction &FI);
324  Instruction *visitFree(CallInst &FI);
325  Instruction *visitLoadInst(LoadInst &LI);
326  Instruction *visitStoreInst(StoreInst &SI);
327  Instruction *visitBranchInst(BranchInst &BI);
328  Instruction *visitSwitchInst(SwitchInst &SI);
329  Instruction *visitReturnInst(ReturnInst &RI);
330  Instruction *visitInsertValueInst(InsertValueInst &IV);
331  Instruction *visitInsertElementInst(InsertElementInst &IE);
332  Instruction *visitExtractElementInst(ExtractElementInst &EI);
333  Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
334  Instruction *visitExtractValueInst(ExtractValueInst &EV);
335  Instruction *visitLandingPadInst(LandingPadInst &LI);
336
337  // visitInstruction - Specify what to return for unhandled instructions...
338  Instruction *visitInstruction(Instruction &I) { return nullptr; }
339
340  // True when DB dominates all uses of DI execpt UI.
341  // UI must be in the same block as DI.
342  // The routine checks that the DI parent and DB are different.
343  bool dominatesAllUses(const Instruction *DI, const Instruction *UI,
344                        const BasicBlock *DB) const;
345
346  // Replace select with select operand SIOpd in SI-ICmp sequence when possible
347  bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp,
348                                 const unsigned SIOpd);
349
350private:
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 a simplification is possible, stores the simplified result of the
371  /// operation in OperationResult and result of the overflow check in
372  /// OverflowResult, and return true.  If no simplification is possible,
373  /// returns false.
374  bool OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS, Value *RHS,
375                             Instruction &CtxI, Value *&OperationResult,
376                             Constant *&OverflowResult);
377
378  Instruction *visitCallSite(CallSite CS);
379  Instruction *tryOptimizeCall(CallInst *CI);
380  bool transformConstExprCastCall(CallSite CS);
381  Instruction *transformCallThroughTrampoline(CallSite CS,
382                                              IntrinsicInst *Tramp);
383  Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
384                                 bool DoXform = true);
385  Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI);
386  bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS, Instruction &CxtI);
387  bool WillNotOverflowSignedSub(Value *LHS, Value *RHS, Instruction &CxtI);
388  bool WillNotOverflowUnsignedSub(Value *LHS, Value *RHS, Instruction &CxtI);
389  bool WillNotOverflowSignedMul(Value *LHS, Value *RHS, Instruction &CxtI);
390  Value *EmitGEPOffset(User *GEP);
391  Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
392  Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
393
394public:
395  /// \brief Inserts an instruction \p New before instruction \p Old
396  ///
397  /// Also adds the new instruction to the worklist and returns \p New so that
398  /// it is suitable for use as the return from the visitation patterns.
399  Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
400    assert(New && !New->getParent() &&
401           "New instruction already inserted into a basic block!");
402    BasicBlock *BB = Old.getParent();
403    BB->getInstList().insert(&Old, New); // Insert inst
404    Worklist.Add(New);
405    return New;
406  }
407
408  /// \brief Same as InsertNewInstBefore, but also sets the debug loc.
409  Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) {
410    New->setDebugLoc(Old.getDebugLoc());
411    return InsertNewInstBefore(New, Old);
412  }
413
414  /// \brief A combiner-aware RAUW-like routine.
415  ///
416  /// This method is to be used when an instruction is found to be dead,
417  /// replacable with another preexisting expression. Here we add all uses of
418  /// I to the worklist, replace all uses of I with the new value, then return
419  /// I, so that the inst combiner will know that I was modified.
420  Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
421    // If there are no uses to replace, then we return nullptr to indicate that
422    // no changes were made to the program.
423    if (I.use_empty()) return nullptr;
424
425    Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
426
427    // If we are replacing the instruction with itself, this must be in a
428    // segment of unreachable code, so just clobber the instruction.
429    if (&I == V)
430      V = UndefValue::get(I.getType());
431
432    DEBUG(dbgs() << "IC: Replacing " << I << "\n"
433                 << "    with " << *V << '\n');
434
435    I.replaceAllUsesWith(V);
436    return &I;
437  }
438
439  /// Creates a result tuple for an overflow intrinsic \p II with a given
440  /// \p Result and a constant \p Overflow value.
441  Instruction *CreateOverflowTuple(IntrinsicInst *II, Value *Result,
442                                   Constant *Overflow) {
443    Constant *V[] = {UndefValue::get(Result->getType()), Overflow};
444    StructType *ST = cast<StructType>(II->getType());
445    Constant *Struct = ConstantStruct::get(ST, V);
446    return InsertValueInst::Create(Struct, Result, 0);
447  }
448
449  /// \brief Combiner aware instruction erasure.
450  ///
451  /// When dealing with an instruction that has side effects or produces a void
452  /// value, we can't rely on DCE to delete the instruction. Instead, visit
453  /// methods should return the value returned by this function.
454  Instruction *EraseInstFromFunction(Instruction &I) {
455    DEBUG(dbgs() << "IC: ERASE " << I << '\n');
456
457    assert(I.use_empty() && "Cannot erase instruction that is used!");
458    // Make sure that we reprocess all operands now that we reduced their
459    // use counts.
460    if (I.getNumOperands() < 8) {
461      for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
462        if (Instruction *Op = dyn_cast<Instruction>(*i))
463          Worklist.Add(Op);
464    }
465    Worklist.Remove(&I);
466    I.eraseFromParent();
467    MadeIRChange = true;
468    return nullptr; // Don't do anything with FI
469  }
470
471  void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne,
472                        unsigned Depth, Instruction *CxtI) const {
473    return llvm::computeKnownBits(V, KnownZero, KnownOne, DL, Depth, AC, CxtI,
474                                  DT);
475  }
476
477  bool MaskedValueIsZero(Value *V, const APInt &Mask, unsigned Depth = 0,
478                         Instruction *CxtI = nullptr) const {
479    return llvm::MaskedValueIsZero(V, Mask, DL, Depth, AC, CxtI, DT);
480  }
481  unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0,
482                              Instruction *CxtI = nullptr) const {
483    return llvm::ComputeNumSignBits(Op, DL, Depth, AC, CxtI, DT);
484  }
485  void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne,
486                      unsigned Depth = 0, Instruction *CxtI = nullptr) const {
487    return llvm::ComputeSignBit(V, KnownZero, KnownOne, DL, Depth, AC, CxtI,
488                                DT);
489  }
490  OverflowResult computeOverflowForUnsignedMul(Value *LHS, Value *RHS,
491                                               const Instruction *CxtI) {
492    return llvm::computeOverflowForUnsignedMul(LHS, RHS, DL, AC, CxtI, DT);
493  }
494  OverflowResult computeOverflowForUnsignedAdd(Value *LHS, Value *RHS,
495                                               const Instruction *CxtI) {
496    return llvm::computeOverflowForUnsignedAdd(LHS, RHS, DL, AC, CxtI, DT);
497  }
498
499private:
500  /// \brief Performs a few simplifications for operators which are associative
501  /// or commutative.
502  bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
503
504  /// \brief Tries to simplify binary operations which some other binary
505  /// operation distributes over.
506  ///
507  /// It does this by either by factorizing out common terms (eg "(A*B)+(A*C)"
508  /// -> "A*(B+C)") or expanding out if this results in simplifications (eg: "A
509  /// & (B | C) -> (A&B) | (A&C)" if this is a win).  Returns the simplified
510  /// value, or null if it didn't simplify.
511  Value *SimplifyUsingDistributiveLaws(BinaryOperator &I);
512
513  /// \brief Attempts to replace V with a simpler value based on the demanded
514  /// bits.
515  Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, APInt &KnownZero,
516                                 APInt &KnownOne, unsigned Depth,
517                                 Instruction *CxtI);
518  bool SimplifyDemandedBits(Use &U, APInt DemandedMask, APInt &KnownZero,
519                            APInt &KnownOne, unsigned Depth = 0);
520  /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded
521  /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence.
522  Value *SimplifyShrShlDemandedBits(Instruction *Lsr, Instruction *Sftl,
523                                    APInt DemandedMask, APInt &KnownZero,
524                                    APInt &KnownOne);
525
526  /// \brief Tries to simplify operands to an integer instruction based on its
527  /// demanded bits.
528  bool SimplifyDemandedInstructionBits(Instruction &Inst);
529
530  Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
531                                    APInt &UndefElts, unsigned Depth = 0);
532
533  Value *SimplifyVectorOp(BinaryOperator &Inst);
534  Value *SimplifyBSwap(BinaryOperator &Inst);
535
536  // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
537  // which has a PHI node as operand #0, see if we can fold the instruction
538  // into the PHI (which is only possible if all operands to the PHI are
539  // constants).
540  //
541  Instruction *FoldOpIntoPhi(Instruction &I);
542
543  /// \brief Try to rotate an operation below a PHI node, using PHI nodes for
544  /// its operands.
545  Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
546  Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
547  Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
548  Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
549
550  Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
551                        ConstantInt *AndRHS, BinaryOperator &TheAnd);
552
553  Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
554                            bool isSub, Instruction &I);
555  Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, bool isSigned,
556                         bool Inside);
557  Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
558  Instruction *MatchBSwap(BinaryOperator &I);
559  bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
560  Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
561  Instruction *SimplifyMemSet(MemSetInst *MI);
562
563  Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
564
565  /// \brief Returns a value X such that Val = X * Scale, or null if none.
566  ///
567  /// If the multiplication is known not to overflow then NoSignedWrap is set.
568  Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap);
569};
570
571} // end namespace llvm.
572
573#undef DEBUG_TYPE
574
575#endif
576