1 //===-- ConstantFolding.h - Fold instructions into constants --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares routines for folding instructions into constants.
12 // Also, to supplement the basic VMCore ConstantExpr simplifications,
13 // this file declares some additional folding routines that can make use of
14 // TargetData information. These functions cannot go in VMCore due to library
17 //===----------------------------------------------------------------------===//
19 #ifndef LLVM_ANALYSIS_CONSTANTFOLDING_H
20 #define LLVM_ANALYSIS_CONSTANTFOLDING_H
30 /// ConstantFoldInstruction - Attempt to constant fold the specified
31 /// instruction. If successful, the constant result is returned, if not, null
32 /// is returned. Note that this function can only fail when attempting to fold
33 /// instructions like loads and stores, which have no constant expression form.
35 Constant *ConstantFoldInstruction(Instruction *I, const TargetData *TD = 0);
37 /// ConstantFoldConstantExpression - Attempt to fold the constant expression
38 /// using the specified TargetData. If successful, the constant result is
39 /// result is returned, if not, null is returned.
40 Constant *ConstantFoldConstantExpression(const ConstantExpr *CE,
41 const TargetData *TD = 0);
43 /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
44 /// specified operands. If successful, the constant result is returned, if not,
45 /// null is returned. Note that this function can fail when attempting to
46 /// fold instructions like loads and stores, which have no constant expression
49 Constant *ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
50 Constant *const *Ops, unsigned NumOps,
51 const TargetData *TD = 0);
53 /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
54 /// instruction (icmp/fcmp) with the specified operands. If it fails, it
55 /// returns a constant expression of the specified operands.
57 Constant *ConstantFoldCompareInstOperands(unsigned Predicate,
58 Constant *LHS, Constant *RHS,
59 const TargetData *TD = 0);
61 /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
62 /// produce if it is constant and determinable. If this is not determinable,
64 Constant *ConstantFoldLoadFromConstPtr(Constant *C, const TargetData *TD = 0);
66 /// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
67 /// getelementptr constantexpr, return the constant value being addressed by the
68 /// constant expression, or null if something is funny and we can't decide.
69 Constant *ConstantFoldLoadThroughGEPConstantExpr(Constant *C, ConstantExpr *CE);
71 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
72 /// the specified function.
73 bool canConstantFoldCallTo(const Function *F);
75 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
76 /// with the specified arguments, returning null if unsuccessful.
78 ConstantFoldCall(Function *F, Constant *const *Operands, unsigned NumOperands);