InstructionSimplify.h revision 2b749870d0488c3b049edf5d0c8875f56f5b1bed 
1//===-- InstructionSimplify.h - Fold instructions into simpler forms ------===//
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 simpler forms that
11// do not require creating new instructions.  For example, this does constant
12// folding, and can handle identities like (X&0)->0.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
17#define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
18
19namespace llvm {
20  class DominatorTree;
21  class Instruction;
22  class Value;
23  class TargetData;
24
25  /// SimplifyAddInst - Given operands for an Add, see if we can
26  /// fold the result.  If not, this returns null.
27  Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
28                         const TargetData *TD = 0, const DominatorTree *DT = 0);
29
30  /// SimplifyAndInst - Given operands for an And, see if we can
31  /// fold the result.  If not, this returns null.
32  Value *SimplifyAndInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
33                         const DominatorTree *DT = 0);
34
35  /// SimplifyOrInst - Given operands for an Or, see if we can
36  /// fold the result.  If not, this returns null.
37  Value *SimplifyOrInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
38                        const DominatorTree *DT = 0);
39
40  /// SimplifyXorInst - Given operands for a Xor, see if we can
41  /// fold the result.  If not, this returns null.
42  Value *SimplifyXorInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
43                         const DominatorTree *DT = 0);
44
45  /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
46  /// fold the result.  If not, this returns null.
47  Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
48                          const TargetData *TD = 0,
49                          const DominatorTree *DT = 0);
50
51  /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
52  /// fold the result.  If not, this returns null.
53  Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
54                          const TargetData *TD = 0,
55                          const DominatorTree *DT = 0);
56
57  /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
58  /// the result.  If not, this returns null.
59  Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
60                            const TargetData *TD = 0,
61                            const DominatorTree *DT = 0);
62
63  /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
64  /// fold the result.  If not, this returns null.
65  Value *SimplifyGEPInst(Value * const *Ops, unsigned NumOps,
66                         const TargetData *TD = 0, const DominatorTree *DT = 0);
67
68  //=== Helper functions for higher up the class hierarchy.
69
70
71  /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
72  /// fold the result.  If not, this returns null.
73  Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
74                         const TargetData *TD = 0, const DominatorTree *DT = 0);
75
76  /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
77  /// fold the result.  If not, this returns null.
78  Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
79                       const TargetData *TD = 0, const DominatorTree *DT = 0);
80
81  /// SimplifyInstruction - See if we can compute a simplified version of this
82  /// instruction.  If not, this returns null.
83  Value *SimplifyInstruction(Instruction *I, const TargetData *TD = 0,
84                             const DominatorTree *DT = 0);
85
86
87  /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
88  /// delete the From instruction.  In addition to a basic RAUW, this does a
89  /// recursive simplification of the updated instructions.  This catches
90  /// things where one simplification exposes other opportunities.  This only
91  /// simplifies and deletes scalar operations, it does not change the CFG.
92  ///
93  void ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
94                                 const TargetData *TD = 0,
95                                 const DominatorTree *DT = 0);
96} // end namespace llvm
97
98#endif
99
100