lib/MC/MCSymbol.cpp

   1 //===- lib/MC/MCSymbol.cpp - MCSymbol implementation ----------------------===//
   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 #include "llvm/MC/MCSymbol.h"
  11 #include "llvm/MC/MCAsmInfo.h"
  12 #include "llvm/Support/raw_ostream.h"
  13 using namespace llvm;
  14
  15 // Sentinel value for the absolute pseudo section.
  16 const MCSection *MCSymbol::AbsolutePseudoSection =
  17   reinterpret_cast<const MCSection *>(1);
  18
  19 static bool isAcceptableChar(char C) {
  20   if ((C < 'a' || C > 'z') &&
  21       (C < 'A' || C > 'Z') &&
  22       (C < '0' || C > '9') &&
  23       C != '_' && C != '$' && C != '.' && C != '@')
  24     return false;
  25   return true;
  26 }
  27
  28 static char HexDigit(int V) {
  29   return V < 10 ? V+'0' : V+'A'-10;
  30 }
  31
  32 static void MangleLetter(raw_ostream &OS, unsigned char C) {
  33   OS << '_' << HexDigit(C >> 4) << HexDigit(C & 15) << '_';
  34 }
  35
  36 /// NameNeedsEscaping - Return true if the identifier \arg Str needs quotes
  37 /// for this assembler.
  38 static bool NameNeedsEscaping(const StringRef &Str, const MCAsmInfo &MAI) {
  39   assert(!Str.empty() && "Cannot create an empty MCSymbol");
  40
  41   // If the first character is a number, we need quotes.
  42   if (Str[0] >= '0' && Str[0] <= '9')
  43     return true;
  44
  45   // If any of the characters in the string is an unacceptable character, force
  46   // quotes.
  47   for (unsigned i = 0, e = Str.size(); i != e; ++i)
  48     if (!isAcceptableChar(Str[i]))
  49       return true;
  50   return false;
  51 }
  52
  53 static void PrintMangledName(raw_ostream &OS, StringRef Str) {
  54   // The first character is not allowed to be a number.
  55   if (Str[0] >= '0' && Str[0] <= '9') {
  56     MangleLetter(OS, Str[0]);
  57     Str = Str.substr(1);
  58   }
  59
  60   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
  61     if (!isAcceptableChar(Str[i]))
  62       MangleLetter(OS, Str[i]);
  63     else
  64       OS << Str[i];
  65   }
  66 }
  67
  68 /// PrintMangledQuotedName - On systems that support quoted symbols, we still
  69 /// have to escape some (obscure) characters like " and \n which would break the
  70 /// assembler's lexing.
  71 static void PrintMangledQuotedName(raw_ostream &OS, StringRef Str) {
  72   OS << '"';
  73
  74   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
  75     if (Str[i] == '"')
  76       OS << "_QQ_";
  77     else if (Str[i] == '\n')
  78       OS << "_NL_";
  79     else
  80       OS << Str[i];
  81   }
  82   OS << '"';
  83 }
  84
  85
  86 void MCSymbol::print(raw_ostream &OS, const MCAsmInfo *MAI) const {
  87   if (MAI == 0 || !NameNeedsEscaping(getName(), *MAI)) {
  88     OS << getName();
  89     return;
  90   }
  91
  92   // On systems that do not allow quoted names, print with mangling.
  93   if (!MAI->doesAllowQuotesInName())
  94     return PrintMangledName(OS, getName());
  95
  96   // If the string contains a double quote or newline, we still have to mangle
  97   // it.
  98   if (getName().find('"') != std::string::npos ||
  99       getName().find('\n') != std::string::npos)
 100     return PrintMangledQuotedName(OS, getName());
 101
 102   OS << '"' << getName() << '"';
 103 }
 104
 105 void MCSymbol::dump() const {
 106   print(errs(), 0);
 107 }