1//===-- ConstantFolding.h - Fold instructions into constants --------------===// 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// 10// This file declares routines for folding instructions into constants when all 11// operands are constants, for example "sub i32 1, 0" -> "1". 12// 13// Also, to supplement the basic VMCore ConstantExpr simplifications, 14// this file declares some additional folding routines that can make use of 15// TargetData information. These functions cannot go in VMCore due to library 16// dependency issues. 17// 18//===----------------------------------------------------------------------===// 19 20#ifndef LLVM_ANALYSIS_CONSTANTFOLDING_H 21#define LLVM_ANALYSIS_CONSTANTFOLDING_H 22 23namespace llvm { 24 class Constant; 25 class ConstantExpr; 26 class Instruction; 27 class TargetData; 28 class TargetLibraryInfo; 29 class Function; 30 class Type; 31 template<typename T> 32 class ArrayRef; 33 34/// ConstantFoldInstruction - Try to constant fold the specified instruction. 35/// If successful, the constant result is returned, if not, null is returned. 36/// Note that this fails if not all of the operands are constant. Otherwise, 37/// this function can only fail when attempting to fold instructions like loads 38/// and stores, which have no constant expression form. 39Constant *ConstantFoldInstruction(Instruction *I, const TargetData *TD = 0, 40 const TargetLibraryInfo *TLI = 0); 41 42/// ConstantFoldConstantExpression - Attempt to fold the constant expression 43/// using the specified TargetData. If successful, the constant result is 44/// result is returned, if not, null is returned. 45Constant *ConstantFoldConstantExpression(const ConstantExpr *CE, 46 const TargetData *TD = 0, 47 const TargetLibraryInfo *TLI = 0); 48 49/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the 50/// specified operands. If successful, the constant result is returned, if not, 51/// null is returned. Note that this function can fail when attempting to 52/// fold instructions like loads and stores, which have no constant expression 53/// form. 54/// 55Constant *ConstantFoldInstOperands(unsigned Opcode, Type *DestTy, 56 ArrayRef<Constant *> Ops, 57 const TargetData *TD = 0, 58 const TargetLibraryInfo *TLI = 0); 59 60/// ConstantFoldCompareInstOperands - Attempt to constant fold a compare 61/// instruction (icmp/fcmp) with the specified operands. If it fails, it 62/// returns a constant expression of the specified operands. 63/// 64Constant *ConstantFoldCompareInstOperands(unsigned Predicate, 65 Constant *LHS, Constant *RHS, 66 const TargetData *TD = 0, 67 const TargetLibraryInfo *TLI = 0); 68 69/// ConstantFoldInsertValueInstruction - Attempt to constant fold an insertvalue 70/// instruction with the specified operands and indices. The constant result is 71/// returned if successful; if not, null is returned. 72Constant *ConstantFoldInsertValueInstruction(Constant *Agg, Constant *Val, 73 ArrayRef<unsigned> Idxs); 74 75/// ConstantFoldLoadFromConstPtr - Return the value that a load from C would 76/// produce if it is constant and determinable. If this is not determinable, 77/// return null. 78Constant *ConstantFoldLoadFromConstPtr(Constant *C, const TargetData *TD = 0); 79 80/// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a 81/// getelementptr constantexpr, return the constant value being addressed by the 82/// constant expression, or null if something is funny and we can't decide. 83Constant *ConstantFoldLoadThroughGEPConstantExpr(Constant *C, ConstantExpr *CE); 84 85/// ConstantFoldLoadThroughGEPIndices - Given a constant and getelementptr 86/// indices (with an *implied* zero pointer index that is not in the list), 87/// return the constant value being addressed by a virtual load, or null if 88/// something is funny and we can't decide. 89Constant *ConstantFoldLoadThroughGEPIndices(Constant *C, 90 ArrayRef<Constant*> Indices); 91 92/// canConstantFoldCallTo - Return true if its even possible to fold a call to 93/// the specified function. 94bool canConstantFoldCallTo(const Function *F); 95 96/// ConstantFoldCall - Attempt to constant fold a call to the specified function 97/// with the specified arguments, returning null if unsuccessful. 98Constant *ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands, 99 const TargetLibraryInfo *TLI = 0); 100} 101 102#endif 103