LLVM  3.7.0
ConstantFolding.h
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1 //===-- ConstantFolding.h - Fold instructions into constants ----*- C++ -*-===//
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 constants when all
11 // operands are constants, for example "sub i32 1, 0" -> "1".
12 //
13 // Also, to supplement the basic VMCore ConstantExpr simplifications,
14 // this file declares some additional folding routines that can make use of
15 // DataLayout information. These functions cannot go in VMCore due to library
16 // dependency issues.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #ifndef LLVM_ANALYSIS_CONSTANTFOLDING_H
21 #define LLVM_ANALYSIS_CONSTANTFOLDING_H
22 
23 namespace llvm {
24  class Constant;
25  class ConstantExpr;
26  class Instruction;
27  class DataLayout;
28  class TargetLibraryInfo;
29  class Function;
30  class Type;
31  template<typename T>
32  class ArrayRef;
33 
34 /// ConstantFoldInstruction - Try to constant fold the specified instruction.
35 /// If successful, the constant result is returned, if not, null is returned.
36 /// Note that this fails if not all of the operands are constant. Otherwise,
37 /// this function can only fail when attempting to fold instructions like loads
38 /// and stores, which have no constant expression form.
39  Constant *ConstantFoldInstruction(Instruction *I, const DataLayout &DL,
40  const TargetLibraryInfo *TLI = nullptr);
41 
42 /// ConstantFoldConstantExpression - Attempt to fold the constant expression
43 /// using the specified DataLayout. If successful, the constant result is
44 /// result is returned, if not, null is returned.
45  Constant *
46  ConstantFoldConstantExpression(const ConstantExpr *CE, const DataLayout &DL,
47  const TargetLibraryInfo *TLI = nullptr);
48 
49 /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
50 /// specified operands. If successful, the constant result is returned, if not,
51 /// null is returned. Note that this function can fail when attempting to
52 /// fold instructions like loads and stores, which have no constant expression
53 /// form.
54 ///
55  Constant *ConstantFoldInstOperands(unsigned Opcode, Type *DestTy,
56  ArrayRef<Constant *> Ops,
57  const DataLayout &DL,
58  const TargetLibraryInfo *TLI = nullptr);
59 
60 /// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
61 /// instruction (icmp/fcmp) with the specified operands. If it fails, it
62 /// returns a constant expression of the specified operands.
63 ///
64  Constant *
66  Constant *RHS, const DataLayout &DL,
67  const TargetLibraryInfo *TLI = nullptr);
68 
69 /// ConstantFoldInsertValueInstruction - Attempt to constant fold an insertvalue
70 /// instruction with the specified operands and indices. The constant result is
71 /// returned if successful; if not, null is returned.
73  ArrayRef<unsigned> Idxs);
74 
75 /// \brief Attempt to constant fold an extractvalue instruction with the
76 /// specified operands and indices. The constant result is returned if
77 /// successful; if not, null is returned.
79  ArrayRef<unsigned> Idxs);
80 
81 /// \brief Attempt to constant fold an extractelement instruction with the
82 /// specified operands and indices. The constant result is returned if
83 /// successful; if not, null is returned.
85 
86 /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
87 /// produce if it is constant and determinable. If this is not determinable,
88 /// return null.
89 Constant *ConstantFoldLoadFromConstPtr(Constant *C, const DataLayout &DL);
90 
91 /// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
92 /// getelementptr constantexpr, return the constant value being addressed by the
93 /// constant expression, or null if something is funny and we can't decide.
95 
96 /// ConstantFoldLoadThroughGEPIndices - Given a constant and getelementptr
97 /// indices (with an *implied* zero pointer index that is not in the list),
98 /// return the constant value being addressed by a virtual load, or null if
99 /// something is funny and we can't decide.
101  ArrayRef<Constant*> Indices);
102 
103 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
104 /// the specified function.
105 bool canConstantFoldCallTo(const Function *F);
106 
107 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
108 /// with the specified arguments, returning null if unsuccessful.
109 Constant *ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
110  const TargetLibraryInfo *TLI = nullptr);
111 }
112 
113 #endif
Constant * ConstantFoldLoadThroughGEPConstantExpr(Constant *C, ConstantExpr *CE)
ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a getelementptr constantexpr, return the constant value being addressed by the constant expression, or null if something is funny and we can't decide.
bool canConstantFoldCallTo(const Function *F)
canConstantFoldCallTo - Return true if its even possible to fold a call to the specified function...
Constant * ConstantFoldExtractElementInstruction(Constant *Val, Constant *Idx)
Attempt to constant fold an extractelement instruction with the specified operands and indices...
F(f)
Constant * ConstantFoldConstantExpression(const ConstantExpr *CE, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldConstantExpression - Attempt to fold the constant expression using the specified DataLayo...
Constant * ConstantFoldLoadFromConstPtr(Constant *C, const DataLayout &DL)
ConstantFoldLoadFromConstPtr - Return the value that a load from C would produce if it is constant an...
Constant * ConstantFoldInsertValueInstruction(Constant *Agg, Constant *Val, ArrayRef< unsigned > Idxs)
ConstantFoldInsertValueInstruction - Attempt to constant fold an insertvalue instruction with the spe...
Constant * ConstantFoldInstruction(Instruction *I, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldInstruction - Try to constant fold the specified instruction.
SI Fold Operands
Constant * ConstantFoldCompareInstOperands(unsigned Predicate, Constant *LHS, Constant *RHS, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldCompareInstOperands - Attempt to constant fold a compare instruction (icmp/fcmp) with the...
Constant * ConstantFoldInstOperands(unsigned Opcode, Type *DestTy, ArrayRef< Constant * > Ops, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldInstOperands - Attempt to constant fold an instruction with the specified operands...
#define I(x, y, z)
Definition: MD5.cpp:54
C - The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
Constant * ConstantFoldExtractValueInstruction(Constant *Agg, ArrayRef< unsigned > Idxs)
Attempt to constant fold an extractvalue instruction with the specified operands and indices...
Constant * ConstantFoldLoadThroughGEPIndices(Constant *C, ArrayRef< Constant * > Indices)
ConstantFoldLoadThroughGEPIndices - Given a constant and getelementptr indices (with an implied zero ...
Constant * ConstantFoldCall(Function *F, ArrayRef< Constant * > Operands, const TargetLibraryInfo *TLI=nullptr)
ConstantFoldCall - Attempt to constant fold a call to the specified function with the specified argum...