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 23 namespace 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. 39 Constant *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. 45 Constant *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 /// 55 Constant *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 /// 64 Constant *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. 72 Constant *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. 78 Constant *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. 83 Constant *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. 89 Constant *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. 94 bool 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. 98 Constant *ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands, 99 const TargetLibraryInfo *TLI = 0); 100 } 101 102 #endif 103
