| //===-- InstructionSimplify.h - Fold instrs into simpler forms --*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file declares routines for folding instructions into simpler forms |
| // that do not require creating new instructions. This does constant folding |
| // ("add i32 1, 1" -> "2") but can also handle non-constant operands, either |
| // returning a constant ("and i32 %x, 0" -> "0") or an already existing value |
| // ("and i32 %x, %x" -> "%x"). If the simplification is also an instruction |
| // then it dominates the original instruction. |
| // |
| // These routines implicitly resolve undef uses. The easiest way to be safe when |
| // using these routines to obtain simplified values for existing instructions is |
| // to always replace all uses of the instructions with the resulting simplified |
| // values. This will prevent other code from seeing the same undef uses and |
| // resolving them to different values. |
| // |
| // They require that all the IR that they encounter be valid and inserted into a |
| // parent function. |
| // |
| // Additionally, these routines can't simplify to the instructions that are not |
| // def-reachable, meaning we can't just scan the basic block for instructions |
| // to simplify to. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H |
| #define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H |
| |
| #include "llvm/IR/PatternMatch.h" |
| |
| namespace llvm { |
| |
| template <typename T, typename... TArgs> class AnalysisManager; |
| template <class T> class ArrayRef; |
| class AssumptionCache; |
| class BinaryOperator; |
| class CallBase; |
| class DataLayout; |
| class DominatorTree; |
| class Function; |
| class Instruction; |
| struct LoopStandardAnalysisResults; |
| class MDNode; |
| class Pass; |
| template <class T, unsigned n> class SmallSetVector; |
| class TargetLibraryInfo; |
| class Type; |
| class Value; |
| |
| /// InstrInfoQuery provides an interface to query additional information for |
| /// instructions like metadata or keywords like nsw, which provides conservative |
| /// results if the users specified it is safe to use. |
| struct InstrInfoQuery { |
| InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {} |
| InstrInfoQuery() = default; |
| bool UseInstrInfo = true; |
| |
| MDNode *getMetadata(const Instruction *I, unsigned KindID) const { |
| if (UseInstrInfo) |
| return I->getMetadata(KindID); |
| return nullptr; |
| } |
| |
| template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const { |
| if (UseInstrInfo) |
| return Op->hasNoUnsignedWrap(); |
| return false; |
| } |
| |
| template <class InstT> bool hasNoSignedWrap(const InstT *Op) const { |
| if (UseInstrInfo) |
| return Op->hasNoSignedWrap(); |
| return false; |
| } |
| |
| bool isExact(const BinaryOperator *Op) const { |
| if (UseInstrInfo && isa<PossiblyExactOperator>(Op)) |
| return cast<PossiblyExactOperator>(Op)->isExact(); |
| return false; |
| } |
| }; |
| |
| struct SimplifyQuery { |
| const DataLayout &DL; |
| const TargetLibraryInfo *TLI = nullptr; |
| const DominatorTree *DT = nullptr; |
| AssumptionCache *AC = nullptr; |
| const Instruction *CxtI = nullptr; |
| |
| // Wrapper to query additional information for instructions like metadata or |
| // keywords like nsw, which provides conservative results if those cannot |
| // be safely used. |
| const InstrInfoQuery IIQ; |
| |
| /// Controls whether simplifications are allowed to constrain the range of |
| /// possible values for uses of undef. If it is false, simplifications are not |
| /// allowed to assume a particular value for a use of undef for example. |
| bool CanUseUndef = true; |
| |
| SimplifyQuery(const DataLayout &DL, const Instruction *CXTI = nullptr) |
| : DL(DL), CxtI(CXTI) {} |
| |
| SimplifyQuery(const DataLayout &DL, const TargetLibraryInfo *TLI, |
| const DominatorTree *DT = nullptr, |
| AssumptionCache *AC = nullptr, |
| const Instruction *CXTI = nullptr, bool UseInstrInfo = true, |
| bool CanUseUndef = true) |
| : DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo), |
| CanUseUndef(CanUseUndef) {} |
| SimplifyQuery getWithInstruction(Instruction *I) const { |
| SimplifyQuery Copy(*this); |
| Copy.CxtI = I; |
| return Copy; |
| } |
| SimplifyQuery getWithoutUndef() const { |
| SimplifyQuery Copy(*this); |
| Copy.CanUseUndef = false; |
| return Copy; |
| } |
| |
| /// If CanUseUndef is true, returns whether \p V is undef. |
| /// Otherwise always return false. |
| bool isUndefValue(Value *V) const { |
| if (!CanUseUndef) |
| return false; |
| |
| using namespace PatternMatch; |
| return match(V, m_Undef()); |
| } |
| }; |
| |
| // NOTE: the explicit multiple argument versions of these functions are |
| // deprecated. |
| // Please use the SimplifyQuery versions in new code. |
| |
| /// Given operands for an Add, fold the result or return null. |
| Value *simplifyAddInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a Sub, fold the result or return null. |
| Value *simplifySubInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a Mul, fold the result or return null. |
| Value *simplifyMulInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an SDiv, fold the result or return null. |
| Value *simplifySDivInst(Value *LHS, Value *RHS, bool IsExact, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a UDiv, fold the result or return null. |
| Value *simplifyUDivInst(Value *LHS, Value *RHS, bool IsExact, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an SRem, fold the result or return null. |
| Value *simplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); |
| |
| /// Given operands for a URem, fold the result or return null. |
| Value *simplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); |
| |
| /// Given operand for an FNeg, fold the result or return null. |
| Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, const SimplifyQuery &Q); |
| |
| |
| /// Given operands for an FAdd, fold the result or return null. |
| Value * |
| simplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q, |
| fp::ExceptionBehavior ExBehavior = fp::ebIgnore, |
| RoundingMode Rounding = RoundingMode::NearestTiesToEven); |
| |
| /// Given operands for an FSub, fold the result or return null. |
| Value * |
| simplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q, |
| fp::ExceptionBehavior ExBehavior = fp::ebIgnore, |
| RoundingMode Rounding = RoundingMode::NearestTiesToEven); |
| |
| /// Given operands for an FMul, fold the result or return null. |
| Value * |
| simplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q, |
| fp::ExceptionBehavior ExBehavior = fp::ebIgnore, |
| RoundingMode Rounding = RoundingMode::NearestTiesToEven); |
| |
| /// Given operands for the multiplication of a FMA, fold the result or return |
| /// null. In contrast to simplifyFMulInst, this function will not perform |
| /// simplifications whose unrounded results differ when rounded to the argument |
| /// type. |
| Value *simplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q, |
| fp::ExceptionBehavior ExBehavior = fp::ebIgnore, |
| RoundingMode Rounding = RoundingMode::NearestTiesToEven); |
| |
| /// Given operands for an FDiv, fold the result or return null. |
| Value * |
| simplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q, |
| fp::ExceptionBehavior ExBehavior = fp::ebIgnore, |
| RoundingMode Rounding = RoundingMode::NearestTiesToEven); |
| |
| /// Given operands for an FRem, fold the result or return null. |
| Value * |
| simplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q, |
| fp::ExceptionBehavior ExBehavior = fp::ebIgnore, |
| RoundingMode Rounding = RoundingMode::NearestTiesToEven); |
| |
| /// Given operands for a Shl, fold the result or return null. |
| Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a LShr, fold the result or return null. |
| Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a AShr, fold the result or return nulll. |
| Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an And, fold the result or return null. |
| Value *simplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); |
| |
| /// Given operands for an Or, fold the result or return null. |
| Value *simplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); |
| |
| /// Given operands for an Xor, fold the result or return null. |
| Value *simplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); |
| |
| /// Given operands for an ICmpInst, fold the result or return null. |
| Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an FCmpInst, fold the result or return null. |
| Value *simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| FastMathFlags FMF, const SimplifyQuery &Q); |
| |
| /// Given operands for a SelectInst, fold the result or return null. |
| Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a GetElementPtrInst, fold the result or return null. |
| Value *simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices, |
| bool InBounds, const SimplifyQuery &Q); |
| |
| /// Given operands for an InsertValueInst, fold the result or return null. |
| Value *simplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an InsertElement, fold the result or return null. |
| Value *simplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an ExtractValueInst, fold the result or return null. |
| Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for an ExtractElementInst, fold the result or return null. |
| Value *simplifyExtractElementInst(Value *Vec, Value *Idx, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a CastInst, fold the result or return null. |
| Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a ShuffleVectorInst, fold the result or return null. |
| /// See class ShuffleVectorInst for a description of the mask representation. |
| Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1, ArrayRef<int> Mask, |
| Type *RetTy, const SimplifyQuery &Q); |
| |
| //=== Helper functions for higher up the class hierarchy. |
| |
| /// Given operands for a CmpInst, fold the result or return null. |
| Value *simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, |
| const SimplifyQuery &Q); |
| |
| /// Given operand for a UnaryOperator, fold the result or return null. |
| Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q); |
| |
| /// Given operand for a UnaryOperator, fold the result or return null. |
| /// Try to use FastMathFlags when folding the result. |
| Value *simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a BinaryOperator, fold the result or return null. |
| Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, |
| const SimplifyQuery &Q); |
| |
| /// Given operands for a BinaryOperator, fold the result or return null. |
| /// Try to use FastMathFlags when folding the result. |
| Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, FastMathFlags FMF, |
| const SimplifyQuery &Q); |
| |
| /// Given a callsite, callee, and arguments, fold the result or return null. |
| Value *simplifyCall(CallBase *Call, Value *Callee, ArrayRef<Value *> Args, |
| const SimplifyQuery &Q); |
| |
| /// Given a constrained FP intrinsic call, tries to compute its simplified |
| /// version. Returns a simplified result or null. |
| /// |
| /// This function provides an additional contract: it guarantees that if |
| /// simplification succeeds that the intrinsic is side effect free. As a result, |
| /// successful simplification can be used to delete the intrinsic not just |
| /// replace its result. |
| Value *simplifyConstrainedFPCall(CallBase *Call, const SimplifyQuery &Q); |
| |
| /// Given an operand for a Freeze, see if we can fold the result. |
| /// If not, this returns null. |
| Value *simplifyFreezeInst(Value *Op, const SimplifyQuery &Q); |
| |
| /// Given a load instruction and its pointer operand, fold the result or return |
| /// null. |
| Value *simplifyLoadInst(LoadInst *LI, Value *PtrOp, const SimplifyQuery &Q); |
| |
| /// See if we can compute a simplified version of this instruction. If not, |
| /// return null. |
| Value *simplifyInstruction(Instruction *I, const SimplifyQuery &Q); |
| |
| /// Like \p simplifyInstruction but the operands of \p I are replaced with |
| /// \p NewOps. Returns a simplified value, or null if none was found. |
| Value * |
| simplifyInstructionWithOperands(Instruction *I, ArrayRef<Value *> NewOps, |
| const SimplifyQuery &Q); |
| |
| /// See if V simplifies when its operand Op is replaced with RepOp. If not, |
| /// return null. |
| /// AllowRefinement specifies whether the simplification can be a refinement |
| /// (e.g. 0 instead of poison), or whether it needs to be strictly identical. |
| /// Op and RepOp can be assumed to not be poison when determining refinement. |
| Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, |
| const SimplifyQuery &Q, bool AllowRefinement); |
| |
| /// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively. |
| /// |
| /// This first performs a normal RAUW of I with SimpleV. It then recursively |
| /// attempts to simplify those users updated by the operation. The 'I' |
| /// instruction must not be equal to the simplified value 'SimpleV'. |
| /// If UnsimplifiedUsers is provided, instructions that could not be simplified |
| /// are added to it. |
| /// |
| /// The function returns true if any simplifications were performed. |
| bool replaceAndRecursivelySimplify( |
| Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr, |
| const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr, |
| SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr); |
| |
| // These helper functions return a SimplifyQuery structure that contains as |
| // many of the optional analysis we use as are currently valid. This is the |
| // strongly preferred way of constructing SimplifyQuery in passes. |
| const SimplifyQuery getBestSimplifyQuery(Pass &, Function &); |
| template <class T, class... TArgs> |
| const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &, |
| Function &); |
| const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &, |
| const DataLayout &); |
| } // end namespace llvm |
| |
| #endif |