MCSymbol.h revision 525a3a67c16c2d1d9ce9d75ed1b44296be6c2270 
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    /// IsUsedInExpr - True if this symbol has been used in an expression and
56    /// cannot be redefined.
57    unsigned IsUsedInExpr : 1;
58
59  private:  // MCContext creates and uniques these.
60    friend class MCContext;
61    MCSymbol(StringRef name, bool isTemporary)
62      : Name(name), Section(0), Value(0),
63        IsTemporary(isTemporary), IsUsedInExpr(false) {}
64
65    MCSymbol(const MCSymbol&);       // DO NOT IMPLEMENT
66    void operator=(const MCSymbol&); // DO NOT IMPLEMENT
67  public:
68    /// getName - Get the symbol name.
69    StringRef getName() const { return Name; }
70
71    /// @name Accessors
72    /// @{
73
74    /// isTemporary - Check if this is an assembler temporary symbol.
75    bool isTemporary() const { return IsTemporary; }
76
77    /// isUsedInExpr - Check if this is an assembler temporary symbol.
78    bool isUsedInExpr() const { return IsUsedInExpr; }
79    void setUsedInExpr(bool Value) { IsUsedInExpr = Value; }
80
81    /// @}
82    /// @name Associated Sections
83    /// @{
84
85    /// isDefined - Check if this symbol is defined (i.e., it has an address).
86    ///
87    /// Defined symbols are either absolute or in some section.
88    bool isDefined() const {
89      return Section != 0;
90    }
91
92    /// isInSection - Check if this symbol is defined in some section (i.e., it
93    /// is defined but not absolute).
94    bool isInSection() const {
95      return isDefined() && !isAbsolute();
96    }
97
98    /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
99    bool isUndefined() const {
100      return !isDefined();
101    }
102
103    /// isAbsolute - Check if this is an absolute symbol.
104    bool isAbsolute() const {
105      return Section == AbsolutePseudoSection;
106    }
107
108    /// getSection - Get the section associated with a defined, non-absolute
109    /// symbol.
110    const MCSection &getSection() const {
111      assert(isInSection() && "Invalid accessor!");
112      return *Section;
113    }
114
115    /// setSection - Mark the symbol as defined in the section \arg S.
116    void setSection(const MCSection &S) { Section = &S; }
117
118    /// setUndefined - Mark the symbol as undefined.
119    void setUndefined() {
120      Section = 0;
121    }
122
123    /// setAbsolute - Mark the symbol as absolute.
124    void setAbsolute() { Section = AbsolutePseudoSection; }
125
126    /// @}
127    /// @name Variable Symbols
128    /// @{
129
130    /// isVariable - Check if this is a variable symbol.
131    bool isVariable() const {
132      return Value != 0;
133    }
134
135    /// getValue() - Get the value for variable symbols.
136    const MCExpr *getVariableValue() const {
137      assert(isVariable() && "Invalid accessor!");
138      return Value;
139    }
140
141    void setVariableValue(const MCExpr *Value);
142
143    /// @}
144
145    /// print - Print the value to the stream \arg OS.
146    void print(raw_ostream &OS) const;
147
148    /// dump - Print the value to stderr.
149    void dump() const;
150  };
151
152  inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
153    Sym.print(OS);
154    return OS;
155  }
156} // end namespace llvm
157
158#endif
159