src/llvm/include/llvm/MC/MCSymbol.h

   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
  66     MCSymbol(const MCSymbol&) LLVM_DELETED_FUNCTION;
  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