MCSymbol.h revision c28cc093e3b5b8601cb5024a5365a6f31f49839a 
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  ///
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  private:  // MCContext creates and uniques these.
57    friend class MCContext;
58    MCSymbol(StringRef name, bool isTemporary)
59      : Name(name), Section(0), Value(0), IsTemporary(isTemporary) {}
60
61    MCSymbol(const MCSymbol&);       // DO NOT IMPLEMENT
62    void operator=(const MCSymbol&); // DO NOT IMPLEMENT
63  public:
64    /// getName - Get the symbol name.
65    StringRef getName() const { return Name; }
66
67    /// @name Symbol Type
68    /// @{
69
70    /// isTemporary - Check if this is an assembler temporary symbol.
71    bool isTemporary() const {
72      return IsTemporary;
73    }
74
75    /// @}
76    /// @name Associated Sections
77    /// @{
78
79    /// isDefined - Check if this symbol is defined (i.e., it has an address).
80    ///
81    /// Defined symbols are either absolute or in some section.
82    bool isDefined() const {
83      return Section != 0;
84    }
85
86    /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
87    bool isUndefined() const {
88      return !isDefined();
89    }
90
91    /// isAbsolute - Check if this is an absolute symbol.
92    bool isAbsolute() const {
93      return Section == AbsolutePseudoSection;
94    }
95
96    /// getSection - Get the section associated with a defined, non-absolute
97    /// symbol.
98    const MCSection &getSection() const {
99      assert(!isUndefined() && !isAbsolute() && "Invalid accessor!");
100      return *Section;
101    }
102
103    /// setSection - Mark the symbol as defined in the section \arg S.
104    void setSection(const MCSection &S) { Section = &S; }
105
106    /// setUndefined - Mark the symbol as undefined.
107    void setUndefined() {
108      Section = 0;
109    }
110
111    /// setAbsolute - Mark the symbol as absolute.
112    void setAbsolute() { Section = AbsolutePseudoSection; }
113
114    /// @}
115    /// @name Variable Symbols
116    /// @{
117
118    /// isVariable - Check if this is a variable symbol.
119    bool isVariable() const {
120      return Value != 0;
121    }
122
123    /// getValue() - Get the value for variable symbols, or null if the symbol
124    /// is not a variable.
125    const MCExpr *getValue() const { return Value; }
126
127    void setValue(const MCExpr *Value) {
128      this->Value = Value;
129    }
130
131    /// @}
132
133    /// print - Print the value to the stream \arg OS.
134    void print(raw_ostream &OS) const;
135
136    /// dump - Print the value to stderr.
137    void dump() const;
138  };
139
140  inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
141    Sym.print(OS);
142    return OS;
143  }
144} // end namespace llvm
145
146#endif
147