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