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//===- MCSymbol.h - Machine Code Symbols ------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the declaration of the MCSymbol class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCSYMBOL_H
#define LLVM_MC_MCSYMBOL_H
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
class MCExpr;
class MCSection;
class MCContext;
class raw_ostream;
/// MCSymbol - Instances of this class represent a symbol name in the MC file,
/// and MCSymbols are created and unique'd by the MCContext class. MCSymbols
/// should only be constructed with valid names for the object file.
///
/// If the symbol is defined/emitted into the current translation unit, the
/// Section member is set to indicate what section it lives in. Otherwise, if
/// it is a reference to an external entity, it has a null section.
class MCSymbol {
// Special sentinal value for the absolute pseudo section.
//
// FIXME: Use a PointerInt wrapper for this?
static const MCSection *AbsolutePseudoSection;
/// Name - The name of the symbol. The referred-to string data is actually
/// held by the StringMap that lives in MCContext.
StringRef Name;
/// Section - The section the symbol is defined in. This is null for
/// undefined symbols, and the special AbsolutePseudoSection value for
/// absolute symbols.
const MCSection *Section;
/// Value - If non-null, the value for a variable symbol.
const MCExpr *Value;
/// IsTemporary - True if this is an assembler temporary label, which
/// typically does not survive in the .o file's symbol table. Usually
/// "Lfoo" or ".foo".
unsigned IsTemporary : 1;
/// \brief True if this symbol can be redefined.
unsigned IsRedefinable : 1;
/// IsUsed - True if this symbol has been used.
mutable unsigned IsUsed : 1;
private: // MCContext creates and uniques these.
friend class MCExpr;
friend class MCContext;
MCSymbol(StringRef name, bool isTemporary)
: Name(name), Section(nullptr), Value(nullptr),
IsTemporary(isTemporary), IsRedefinable(false), IsUsed(false) {}
MCSymbol(const MCSymbol&) = delete;
void operator=(const MCSymbol&) = delete;
public:
/// getName - Get the symbol name.
StringRef getName() const { return Name; }
/// @name Accessors
/// @{
/// isTemporary - Check if this is an assembler temporary symbol.
bool isTemporary() const { return IsTemporary; }
/// isUsed - Check if this is used.
bool isUsed() const { return IsUsed; }
void setUsed(bool Value) const { IsUsed = Value; }
/// \brief Check if this symbol is redefinable.
bool isRedefinable() const { return IsRedefinable; }
/// \brief Mark this symbol as redefinable.
void setRedefinable(bool Value) { IsRedefinable = Value; }
/// \brief Prepare this symbol to be redefined.
void redefineIfPossible() {
if (IsRedefinable) {
Value = nullptr;
Section = nullptr;
IsRedefinable = false;
}
}
/// @}
/// @name Associated Sections
/// @{
/// isDefined - Check if this symbol is defined (i.e., it has an address).
///
/// Defined symbols are either absolute or in some section.
bool isDefined() const {
return Section != nullptr;
}
/// isInSection - Check if this symbol is defined in some section (i.e., it
/// is defined but not absolute).
bool isInSection() const {
return isDefined() && !isAbsolute();
}
/// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
bool isUndefined() const {
return !isDefined();
}
/// isAbsolute - Check if this is an absolute symbol.
bool isAbsolute() const {
return Section == AbsolutePseudoSection;
}
/// getSection - Get the section associated with a defined, non-absolute
/// symbol.
const MCSection &getSection() const {
assert(isInSection() && "Invalid accessor!");
return *Section;
}
/// setSection - Mark the symbol as defined in the section \p S.
void setSection(const MCSection &S) { Section = &S; }
/// setUndefined - Mark the symbol as undefined.
void setUndefined() {
Section = nullptr;
}
/// setAbsolute - Mark the symbol as absolute.
void setAbsolute() { Section = AbsolutePseudoSection; }
/// @}
/// @name Variable Symbols
/// @{
/// isVariable - Check if this is a variable symbol.
bool isVariable() const {
return Value != nullptr;
}
/// getVariableValue() - Get the value for variable symbols.
const MCExpr *getVariableValue() const {
assert(isVariable() && "Invalid accessor!");
IsUsed = true;
return Value;
}
// AliasedSymbol() - If this is an alias (a = b), return the symbol
// we ultimately point to. For a non-alias, this just returns the symbol
// itself.
const MCSymbol &AliasedSymbol() const;
void setVariableValue(const MCExpr *Value);
/// @}
/// print - Print the value to the stream \p OS.
void print(raw_ostream &OS) const;
/// dump - Print the value to stderr.
void dump() const;
};
inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
Sym.print(OS);
return OS;
}
} // end namespace llvm
#endif
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