llvm-mirror/lib/MC/MCSymbol.cpp

//===- lib/MC/MCSymbol.cpp - MCSymbol implementation ----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;

// Sentinel value for the absolute pseudo section.
const MCSection *MCSymbol::AbsolutePseudoSection =
  reinterpret_cast<const MCSection *>(1);

static bool isAcceptableChar(char C) {
  if ((C < 'a' || C > 'z') &&
      (C < 'A' || C > 'Z') &&
      (C < '0' || C > '9') &&
      C != '_' && C != '$' && C != '.' && C != '@')
    return false;
  return true;
}

/// NameNeedsQuoting - Return true if the identifier \p Str needs quotes to be
/// syntactically correct.
static bool NameNeedsQuoting(StringRef Str) {
  assert(!Str.empty() && "Cannot create an empty MCSymbol");

  // If any of the characters in the string is an unacceptable character, force
  // quotes.
  for (unsigned i = 0, e = Str.size(); i != e; ++i)
    if (!isAcceptableChar(Str[i]))
      return true;
  return false;
}

const MCSymbol &MCSymbol::AliasedSymbol() const {
  const MCSymbol *S = this;
  while (S->isVariable()) {
    const MCExpr *Value = S->getVariableValue();
    if (Value->getKind() != MCExpr::SymbolRef)
      return *S;
    const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
    S = &Ref->getSymbol();
  }
  return *S;
}

void MCSymbol::setVariableValue(const MCExpr *Value) {
  assert(!IsUsed && "Cannot set a variable that has already been used.");
  assert(Value && "Invalid variable value!");
  this->Value = Value;

  // Variables should always be marked as in the same "section" as the value.
  const MCSection *Section = Value->FindAssociatedSection();
  if (Section)
    setSection(*Section);
  else
    setUndefined();
}

void MCSymbol::print(raw_ostream &OS) const {
  // The name for this MCSymbol is required to be a valid target name.  However,
  // some targets support quoting names with funny characters.  If the name
  // contains a funny character, then print it quoted.
  StringRef Name = getName();
  if (!NameNeedsQuoting(Name)) {
    OS << Name;
    return;
  }

  OS << '"';
  for (unsigned I = 0, E = Name.size(); I != E; ++I) {
    char C = Name[I];
    if (C == '\n')
      OS << "\\n";
    else if (C == '"')
      OS << "\\\"";
    else
      OS << C;
  }
  OS << '"';
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void MCSymbol::dump() const {
  print(dbgs());
}
#endif