PseudoSourceValue.cpp revision 87e4592785576c12930d0ffd65b33c7b7d889fc5 
1//===-- llvm/CodeGen/PseudoSourceValue.cpp ----------------------*- 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 implements the PseudoSourceValue class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/CodeGen/MachineFrameInfo.h"
15#include "llvm/CodeGen/PseudoSourceValue.h"
16#include "llvm/DerivedTypes.h"
17#include "llvm/LLVMContext.h"
18#include "llvm/Support/ErrorHandling.h"
19#include "llvm/Support/ManagedStatic.h"
20#include "llvm/Support/raw_ostream.h"
21#include <map>
22using namespace llvm;
23
24static ManagedStatic<PseudoSourceValue[4]> PSVs;
25
26const PseudoSourceValue *PseudoSourceValue::getStack()
27{ return &(*PSVs)[0]; }
28const PseudoSourceValue *PseudoSourceValue::getGOT()
29{ return &(*PSVs)[1]; }
30const PseudoSourceValue *PseudoSourceValue::getJumpTable()
31{ return &(*PSVs)[2]; }
32const PseudoSourceValue *PseudoSourceValue::getConstantPool()
33{ return &(*PSVs)[3]; }
34
35static const char *const PSVNames[] = {
36  "Stack",
37  "GOT",
38  "JumpTable",
39  "ConstantPool"
40};
41
42// FIXME: THIS IS A HACK!!!!
43// Eventually these should be uniqued on LLVMContext rather than in a managed
44// static.  For now, we can safely use the global context for the time being to
45// squeak by.
46PseudoSourceValue::PseudoSourceValue() :
47  Value(Type::getInt8PtrTy(getGlobalContext()),
48        PseudoSourceValueVal) {}
49
50void PseudoSourceValue::printCustom(raw_ostream &O) const {
51  O << PSVNames[this - *PSVs];
52}
53
54namespace {
55  /// FixedStackPseudoSourceValue - A specialized PseudoSourceValue
56  /// for holding FixedStack values, which must include a frame
57  /// index.
58  class FixedStackPseudoSourceValue : public PseudoSourceValue {
59    const int FI;
60  public:
61    explicit FixedStackPseudoSourceValue(int fi) : FI(fi) {}
62
63    virtual bool isConstant(const MachineFrameInfo *MFI) const;
64
65    virtual bool isAliased(const MachineFrameInfo *MFI) const;
66
67    virtual bool mayAlias(const MachineFrameInfo *) const;
68
69    virtual void printCustom(raw_ostream &OS) const {
70      OS << "FixedStack" << FI;
71    }
72  };
73}
74
75static ManagedStatic<std::map<int, const PseudoSourceValue *> > FSValues;
76
77const PseudoSourceValue *PseudoSourceValue::getFixedStack(int FI) {
78  const PseudoSourceValue *&V = (*FSValues)[FI];
79  if (!V)
80    V = new FixedStackPseudoSourceValue(FI);
81  return V;
82}
83
84bool PseudoSourceValue::isConstant(const MachineFrameInfo *) const {
85  if (this == getStack())
86    return false;
87  if (this == getGOT() ||
88      this == getConstantPool() ||
89      this == getJumpTable())
90    return true;
91  llvm_unreachable("Unknown PseudoSourceValue!");
92  return false;
93}
94
95bool PseudoSourceValue::isAliased(const MachineFrameInfo *MFI) const {
96  if (this == getStack() ||
97      this == getGOT() ||
98      this == getConstantPool() ||
99      this == getJumpTable())
100    return false;
101  llvm_unreachable("Unknown PseudoSourceValue!");
102  return true;
103}
104
105bool PseudoSourceValue::mayAlias(const MachineFrameInfo *MFI) const {
106  if (this == getGOT() ||
107      this == getConstantPool() ||
108      this == getJumpTable())
109    return false;
110  return true;
111}
112
113bool FixedStackPseudoSourceValue::isConstant(const MachineFrameInfo *MFI) const{
114  return MFI && MFI->isImmutableObjectIndex(FI);
115}
116
117bool FixedStackPseudoSourceValue::isAliased(const MachineFrameInfo *MFI) const {
118  // Negative frame indices are used for special things that don't
119  // appear in LLVM IR. Non-negative indices may be used for things
120  // like static allocas.
121  if (!MFI)
122    return FI >= 0;
123  // Spill slots should not alias others.
124  return !MFI->isFixedObjectIndex(FI) && !MFI->isSpillSlotObjectIndex(FI);
125}
126
127bool FixedStackPseudoSourceValue::mayAlias(const MachineFrameInfo *MFI) const {
128  if (!MFI)
129    return true;
130  // Spill slots will not alias any LLVM IR value.
131  return !MFI->isSpillSlotObjectIndex(FI);
132}
133