InstructionSimplify.h revision 593faa53fa6d89841e601cc4571d143a6a05f0b4 
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
11// that do not require creating new instructions.  This does constant folding
12// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
13// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
14// ("and i32 %x, %x" -> "%x").  If the simplification is also an instruction
15// then it dominates the original instruction.
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
20#define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
21
22namespace llvm {
23  class DominatorTree;
24  class Instruction;
25  class Value;
26  class TargetData;
27
28  /// SimplifyAddInst - Given operands for an Add, see if we can
29  /// fold the result.  If not, this returns null.
30  Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
31                         const TargetData *TD = 0, const DominatorTree *DT = 0);
32
33  /// SimplifySubInst - Given operands for a Sub, see if we can
34  /// fold the result.  If not, this returns null.
35  Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
36                         const TargetData *TD = 0, const DominatorTree *DT = 0);
37
38  /// SimplifyMulInst - Given operands for a Mul, see if we can
39  /// fold the result.  If not, this returns null.
40  Value *SimplifyMulInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
41                         const DominatorTree *DT = 0);
42
43  /// SimplifySDivInst - Given operands for an SDiv, see if we can
44  /// fold the result.  If not, this returns null.
45  Value *SimplifySDivInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
46                          const DominatorTree *DT = 0);
47
48  /// SimplifyUDivInst - Given operands for a UDiv, see if we can
49  /// fold the result.  If not, this returns null.
50  Value *SimplifyUDivInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
51                         const DominatorTree *DT = 0);
52
53  /// SimplifyShlInst - Given operands for a Shl, see if we can
54  /// fold the result.  If not, this returns null.
55  Value *SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD = 0,
56                         const DominatorTree *DT = 0);
57
58  /// SimplifyLShrInst - Given operands for a LShr, see if we can
59  /// fold the result.  If not, this returns null.
60  Value *SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD = 0,
61                          const DominatorTree *DT = 0);
62
63  /// SimplifyAShrInst - Given operands for a AShr, see if we can
64  /// fold the result.  If not, this returns null.
65  Value *SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD = 0,
66                          const DominatorTree *DT = 0);
67
68  /// SimplifyAndInst - Given operands for an And, see if we can
69  /// fold the result.  If not, this returns null.
70  Value *SimplifyAndInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
71                         const DominatorTree *DT = 0);
72
73  /// SimplifyOrInst - Given operands for an Or, see if we can
74  /// fold the result.  If not, this returns null.
75  Value *SimplifyOrInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
76                        const DominatorTree *DT = 0);
77
78  /// SimplifyXorInst - Given operands for a Xor, see if we can
79  /// fold the result.  If not, this returns null.
80  Value *SimplifyXorInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
81                         const DominatorTree *DT = 0);
82
83  /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
84  /// fold the result.  If not, this returns null.
85  Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
86                          const TargetData *TD = 0,
87                          const DominatorTree *DT = 0);
88
89  /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
90  /// fold the result.  If not, this returns null.
91  Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
92                          const TargetData *TD = 0,
93                          const DominatorTree *DT = 0);
94
95  /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
96  /// the result.  If not, this returns null.
97  Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
98                            const TargetData *TD = 0,
99                            const DominatorTree *DT = 0);
100
101  /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
102  /// fold the result.  If not, this returns null.
103  Value *SimplifyGEPInst(Value * const *Ops, unsigned NumOps,
104                         const TargetData *TD = 0, const DominatorTree *DT = 0);
105
106  //=== Helper functions for higher up the class hierarchy.
107
108
109  /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
110  /// fold the result.  If not, this returns null.
111  Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
112                         const TargetData *TD = 0, const DominatorTree *DT = 0);
113
114  /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
115  /// fold the result.  If not, this returns null.
116  Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
117                       const TargetData *TD = 0, const DominatorTree *DT = 0);
118
119  /// SimplifyInstruction - See if we can compute a simplified version of this
120  /// instruction.  If not, this returns null.
121  Value *SimplifyInstruction(Instruction *I, const TargetData *TD = 0,
122                             const DominatorTree *DT = 0);
123
124
125  /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
126  /// delete the From instruction.  In addition to a basic RAUW, this does a
127  /// recursive simplification of the updated instructions.  This catches
128  /// things where one simplification exposes other opportunities.  This only
129  /// simplifies and deletes scalar operations, it does not change the CFG.
130  ///
131  void ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
132                                 const TargetData *TD = 0,
133                                 const DominatorTree *DT = 0);
134} // end namespace llvm
135
136#endif
137
138