MCSymbol.h revision daf97333697e1d243e531f4be648b1640d6a58bb 
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
19namespace llvm {
20  class MCExpr;
21  class MCSection;
22  class MCContext;
23  class raw_ostream;
24
25  /// MCSymbol - Instances of this class represent a symbol name in the MC file,
26  /// and MCSymbols are created and unique'd by the MCContext class.  MCSymbols
27  /// should only be constructed with valid names for the object file.
28  ///
29  /// If the symbol is defined/emitted into the current translation unit, the
30  /// Section member is set to indicate what section it lives in.  Otherwise, if
31  /// it is a reference to an external entity, it has a null section.
32  class MCSymbol {
33    // Special sentinal value for the absolute pseudo section.
34    //
35    // FIXME: Use a PointerInt wrapper for this?
36    static const MCSection *AbsolutePseudoSection;
37
38    /// Name - The name of the symbol.  The referred-to string data is actually
39    /// held by the StringMap that lives in MCContext.
40    StringRef Name;
41
42    /// Section - The section the symbol is defined in. This is null for
43    /// undefined symbols, and the special AbsolutePseudoSection value for
44    /// absolute symbols.
45    const MCSection *Section;
46
47    /// Value - If non-null, the value for a variable symbol.
48    const MCExpr *Value;
49
50    /// IsTemporary - True if this is an assembler temporary label, which
51    /// typically does not survive in the .o file's symbol table.  Usually
52    /// "Lfoo" or ".foo".
53    unsigned IsTemporary : 1;
54
55  private:  // MCContext creates and uniques these.
56    friend class MCContext;
57    MCSymbol(StringRef name, bool isTemporary)
58      : Name(name), Section(0), Value(0), IsTemporary(isTemporary) {}
59
60    MCSymbol(const MCSymbol&);       // DO NOT IMPLEMENT
61    void operator=(const MCSymbol&); // DO NOT IMPLEMENT
62  public:
63    /// getName - Get the symbol name.
64    StringRef getName() const { return Name; }
65
66    /// @name Symbol Type
67    /// @{
68
69    /// isTemporary - Check if this is an assembler temporary symbol.
70    bool isTemporary() const {
71      return IsTemporary;
72    }
73
74    /// @}
75    /// @name Associated Sections
76    /// @{
77
78    /// isDefined - Check if this symbol is defined (i.e., it has an address).
79    ///
80    /// Defined symbols are either absolute or in some section.
81    bool isDefined() const {
82      return Section != 0;
83    }
84
85    /// isInSection - Check if this symbol is defined in some section (i.e., it
86    /// is defined but not absolute).
87    bool isInSection() const {
88      return isDefined() && !isAbsolute();
89    }
90
91    /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
92    bool isUndefined() const {
93      return !isDefined();
94    }
95
96    /// isAbsolute - Check if this is an absolute symbol.
97    bool isAbsolute() const {
98      return Section == AbsolutePseudoSection;
99    }
100
101    /// getSection - Get the section associated with a defined, non-absolute
102    /// symbol.
103    const MCSection &getSection() const {
104      assert(isInSection() && "Invalid accessor!");
105      return *Section;
106    }
107
108    /// setSection - Mark the symbol as defined in the section \arg S.
109    void setSection(const MCSection &S) { Section = &S; }
110
111    /// setUndefined - Mark the symbol as undefined.
112    void setUndefined() {
113      Section = 0;
114    }
115
116    /// setAbsolute - Mark the symbol as absolute.
117    void setAbsolute() { Section = AbsolutePseudoSection; }
118
119    /// @}
120    /// @name Variable Symbols
121    /// @{
122
123    /// isVariable - Check if this is a variable symbol.
124    bool isVariable() const {
125      return Value != 0;
126    }
127
128    /// getValue() - Get the value for variable symbols, or null if the symbol
129    /// is not a variable.
130    const MCExpr *getValue() const { return Value; }
131
132    void setValue(const MCExpr *Value) {
133      this->Value = Value;
134    }
135
136    /// @}
137
138    /// print - Print the value to the stream \arg OS.
139    void print(raw_ostream &OS) const;
140
141    /// dump - Print the value to stderr.
142    void dump() const;
143  };
144
145  inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
146    Sym.print(OS);
147    return OS;
148  }
149} // end namespace llvm
150
151#endif
152