InstructionSimplify.h revision d261dc650a01ac5c51ab10f97f1e35aa6a770721 
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  /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
41  /// fold the result.  If not, this returns null.
42  Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
43                          const TargetData *TD = 0,
44                          const DominatorTree *DT = 0);
45
46  /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
47  /// fold the result.  If not, this returns null.
48  Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
49                          const TargetData *TD = 0,
50                          const DominatorTree *DT = 0);
51
52  /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
53  /// the result.  If not, this returns null.
54  Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
55                            const TargetData *TD = 0,
56                            const DominatorTree *DT = 0);
57
58  /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
59  /// fold the result.  If not, this returns null.
60  Value *SimplifyGEPInst(Value * const *Ops, unsigned NumOps,
61                         const TargetData *TD = 0, const DominatorTree *DT = 0);
62
63  //=== Helper functions for higher up the class hierarchy.
64
65
66  /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
67  /// fold the result.  If not, this returns null.
68  Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
69                         const TargetData *TD = 0, const DominatorTree *DT = 0);
70
71  /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
72  /// fold the result.  If not, this returns null.
73  Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
74                       const TargetData *TD = 0, const DominatorTree *DT = 0);
75
76  /// SimplifyInstruction - See if we can compute a simplified version of this
77  /// instruction.  If not, this returns null.
78  Value *SimplifyInstruction(Instruction *I, const TargetData *TD = 0,
79                             const DominatorTree *DT = 0);
80
81
82  /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
83  /// delete the From instruction.  In addition to a basic RAUW, this does a
84  /// recursive simplification of the updated instructions.  This catches
85  /// things where one simplification exposes other opportunities.  This only
86  /// simplifies and deletes scalar operations, it does not change the CFG.
87  ///
88  void ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
89                                 const TargetData *TD = 0,
90                                 const DominatorTree *DT = 0);
91} // end namespace llvm
92
93#endif
94
95