InstructionSimplify.h revision 81a0dc911586c77421c2255aa417dc9b350b9e20 
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  /// SimplifyFDivInst - Given operands for an FDiv, see if we can
54  /// fold the result.  If not, this returns null.
55  Value *SimplifyFDivInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
56                          const DominatorTree *DT = 0);
57
58  /// SimplifyShlInst - Given operands for a Shl, see if we can
59  /// fold the result.  If not, this returns null.
60  Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
61                         const TargetData *TD = 0, const DominatorTree *DT = 0);
62
63  /// SimplifyLShrInst - Given operands for a LShr, see if we can
64  /// fold the result.  If not, this returns null.
65  Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
66                          const TargetData *TD = 0, const DominatorTree *DT=0);
67
68  /// SimplifyAShrInst - Given operands for a AShr, see if we can
69  /// fold the result.  If not, this returns null.
70  Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
71                          const TargetData *TD = 0,
72                          const DominatorTree *DT = 0);
73
74  /// SimplifyAndInst - Given operands for an And, see if we can
75  /// fold the result.  If not, this returns null.
76  Value *SimplifyAndInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
77                         const DominatorTree *DT = 0);
78
79  /// SimplifyOrInst - Given operands for an Or, see if we can
80  /// fold the result.  If not, this returns null.
81  Value *SimplifyOrInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
82                        const DominatorTree *DT = 0);
83
84  /// SimplifyXorInst - Given operands for a Xor, see if we can
85  /// fold the result.  If not, this returns null.
86  Value *SimplifyXorInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
87                         const DominatorTree *DT = 0);
88
89  /// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
90  /// fold the result.  If not, this returns null.
91  Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
92                          const TargetData *TD = 0,
93                          const DominatorTree *DT = 0);
94
95  /// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
96  /// fold the result.  If not, this returns null.
97  Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
98                          const TargetData *TD = 0,
99                          const DominatorTree *DT = 0);
100
101  /// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
102  /// the result.  If not, this returns null.
103  Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
104                            const TargetData *TD = 0,
105                            const DominatorTree *DT = 0);
106
107  /// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
108  /// fold the result.  If not, this returns null.
109  Value *SimplifyGEPInst(Value * const *Ops, unsigned NumOps,
110                         const TargetData *TD = 0, const DominatorTree *DT = 0);
111
112  //=== Helper functions for higher up the class hierarchy.
113
114
115  /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
116  /// fold the result.  If not, this returns null.
117  Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
118                         const TargetData *TD = 0, const DominatorTree *DT = 0);
119
120  /// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
121  /// fold the result.  If not, this returns null.
122  Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
123                       const TargetData *TD = 0, const DominatorTree *DT = 0);
124
125  /// SimplifyInstruction - See if we can compute a simplified version of this
126  /// instruction.  If not, this returns null.
127  Value *SimplifyInstruction(Instruction *I, const TargetData *TD = 0,
128                             const DominatorTree *DT = 0);
129
130
131  /// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
132  /// delete the From instruction.  In addition to a basic RAUW, this does a
133  /// recursive simplification of the updated instructions.  This catches
134  /// things where one simplification exposes other opportunities.  This only
135  /// simplifies and deletes scalar operations, it does not change the CFG.
136  ///
137  void ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
138                                 const TargetData *TD = 0,
139                                 const DominatorTree *DT = 0);
140} // end namespace llvm
141
142#endif
143
144