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MCSymbol.h
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1 //===- MCSymbol.h - Machine Code Symbols ------------------------*- 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 contains the declaration of the MCSymbol class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_MC_MCSYMBOL_H
15 #define LLVM_MC_MCSYMBOL_H
16 
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Support/Compiler.h"
19 
20 namespace llvm {
21  class MCExpr;
22  class MCSection;
23  class MCContext;
24  class raw_ostream;
25 
26  /// MCSymbol - Instances of this class represent a symbol name in the MC file,
27  /// and MCSymbols are created and unique'd by the MCContext class. MCSymbols
28  /// should only be constructed with valid names for the object file.
29  ///
30  /// If the symbol is defined/emitted into the current translation unit, the
31  /// Section member is set to indicate what section it lives in. Otherwise, if
32  /// it is a reference to an external entity, it has a null section.
33  class MCSymbol {
34  // Special sentinal value for the absolute pseudo section.
35  //
36  // FIXME: Use a PointerInt wrapper for this?
37  static const MCSection *AbsolutePseudoSection;
38 
39  /// Name - The name of the symbol. The referred-to string data is actually
40  /// held by the StringMap that lives in MCContext.
41  StringRef Name;
42 
43  /// Section - The section the symbol is defined in. This is null for
44  /// undefined symbols, and the special AbsolutePseudoSection value for
45  /// absolute symbols.
46  const MCSection *Section;
47 
48  /// Value - If non-null, the value for a variable symbol.
49  const MCExpr *Value;
50 
51  /// IsTemporary - True if this is an assembler temporary label, which
52  /// typically does not survive in the .o file's symbol table. Usually
53  /// "Lfoo" or ".foo".
54  unsigned IsTemporary : 1;
55 
56  /// IsUsed - True if this symbol has been used.
57  mutable unsigned IsUsed : 1;
58 
59  private: // MCContext creates and uniques these.
60  friend class MCExpr;
61  friend class MCContext;
62  MCSymbol(StringRef name, bool isTemporary)
63  : Name(name), Section(0), Value(0),
64  IsTemporary(isTemporary), IsUsed(false) {}
65 
67  void operator=(const MCSymbol&) LLVM_DELETED_FUNCTION;
68  public:
69  /// getName - Get the symbol name.
70  StringRef getName() const { return Name; }
71 
72  /// @name Accessors
73  /// @{
74 
75  /// isTemporary - Check if this is an assembler temporary symbol.
76  bool isTemporary() const { return IsTemporary; }
77 
78  /// isUsed - Check if this is used.
79  bool isUsed() const { return IsUsed; }
80  void setUsed(bool Value) const { IsUsed = Value; }
81 
82  /// @}
83  /// @name Associated Sections
84  /// @{
85 
86  /// isDefined - Check if this symbol is defined (i.e., it has an address).
87  ///
88  /// Defined symbols are either absolute or in some section.
89  bool isDefined() const {
90  return Section != 0;
91  }
92 
93  /// isInSection - Check if this symbol is defined in some section (i.e., it
94  /// is defined but not absolute).
95  bool isInSection() const {
96  return isDefined() && !isAbsolute();
97  }
98 
99  /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
100  bool isUndefined() const {
101  return !isDefined();
102  }
103 
104  /// isAbsolute - Check if this is an absolute symbol.
105  bool isAbsolute() const {
106  return Section == AbsolutePseudoSection;
107  }
108 
109  /// getSection - Get the section associated with a defined, non-absolute
110  /// symbol.
111  const MCSection &getSection() const {
112  assert(isInSection() && "Invalid accessor!");
113  return *Section;
114  }
115 
116  /// setSection - Mark the symbol as defined in the section \p S.
117  void setSection(const MCSection &S) { Section = &S; }
118 
119  /// setUndefined - Mark the symbol as undefined.
120  void setUndefined() {
121  Section = 0;
122  }
123 
124  /// setAbsolute - Mark the symbol as absolute.
125  void setAbsolute() { Section = AbsolutePseudoSection; }
126 
127  /// @}
128  /// @name Variable Symbols
129  /// @{
130 
131  /// isVariable - Check if this is a variable symbol.
132  bool isVariable() const {
133  return Value != 0;
134  }
135 
136  /// getVariableValue() - Get the value for variable symbols.
137  const MCExpr *getVariableValue() const {
138  assert(isVariable() && "Invalid accessor!");
139  IsUsed = true;
140  return Value;
141  }
142 
143  // AliasedSymbol() - If this is an alias (a = b), return the symbol
144  // we ultimately point to. For a non alias, this just returns the symbol
145  // itself.
146  const MCSymbol &AliasedSymbol() const;
147 
148  void setVariableValue(const MCExpr *Value);
149 
150  /// @}
151 
152  /// print - Print the value to the stream \p OS.
153  void print(raw_ostream &OS) const;
154 
155  /// dump - Print the value to stderr.
156  void dump() const;
157  };
158 
159  inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
160  Sym.print(OS);
161  return OS;
162  }
163 } // end namespace llvm
164 
165 #endif
void setAbsolute()
setAbsolute - Mark the symbol as absolute.
Definition: MCSymbol.h:125
const MCSection & getSection() const
Definition: MCSymbol.h:111
const MCExpr * getVariableValue() const
getVariableValue() - Get the value for variable symbols.
Definition: MCSymbol.h:137
#define false
Definition: ConvertUTF.c:64
bool isInSection() const
Definition: MCSymbol.h:95
bool isUsed() const
isUsed - Check if this is used.
Definition: MCSymbol.h:79
bool isAbsolute() const
isAbsolute - Check if this is an absolute symbol.
Definition: MCSymbol.h:105
bool isDefined() const
Definition: MCSymbol.h:89
void setUndefined()
setUndefined - Mark the symbol as undefined.
Definition: MCSymbol.h:120
void setUsed(bool Value) const
Definition: MCSymbol.h:80
void setVariableValue(const MCExpr *Value)
Definition: MCSymbol.cpp:54
#define LLVM_DELETED_FUNCTION
Definition: Compiler.h:137
bool isTemporary() const
isTemporary - Check if this is an assembler temporary symbol.
Definition: MCSymbol.h:76
StringRef getName() const
getName - Get the symbol name.
Definition: MCSymbol.h:70
const MCSymbol & AliasedSymbol() const
Definition: MCSymbol.cpp:42
void setSection(const MCSection &S)
setSection - Mark the symbol as defined in the section S.
Definition: MCSymbol.h:117
raw_ostream & operator<<(raw_ostream &OS, const APInt &I)
Definition: APInt.h:1688
bool isVariable() const
isVariable - Check if this is a variable symbol.
Definition: MCSymbol.h:132
LLVM Value Representation.
Definition: Value.h:66
void print(raw_ostream &OS) const
print - Print the value to the stream OS.
Definition: MCSymbol.cpp:67
bool isUndefined() const
isUndefined - Check if this symbol undefined (i.e., implicitly defined).
Definition: MCSymbol.h:100
void dump() const
dump - Print the value to stderr.
Definition: MCSymbol.cpp:91