lib/MC/MCParser/ELFAsmParser.cpp

   1 //===- ELFAsmParser.cpp - ELF Assembly Parser -----------------------------===//
   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/MCParser/MCAsmParserExtension.h"
  11 #include "llvm/ADT/Twine.h"
  12 #include "llvm/MC/MCAsmInfo.h"
  13 #include "llvm/MC/MCContext.h"
  14 #include "llvm/MC/MCParser/MCAsmLexer.h"
  15 #include "llvm/MC/MCSectionELF.h"
  16 #include "llvm/MC/MCStreamer.h"
  17 #include "llvm/ADT/Twine.h"
  18 using namespace llvm;
  19
  20 namespace {
  21
  22 class ELFAsmParser : public MCAsmParserExtension {
  23   template<bool (ELFAsmParser::*Handler)(StringRef, SMLoc)>
  24   void AddDirectiveHandler(StringRef Directive) {
  25     getParser().AddDirectiveHandler(this, Directive,
  26                                     HandleDirective<ELFAsmParser, Handler>);
  27   }
  28
  29   bool ParseSectionSwitch(StringRef Section, unsigned Type,
  30                           unsigned Flags, SectionKind Kind);
  31
  32 public:
  33   ELFAsmParser() {}
  34
  35   virtual void Initialize(MCAsmParser &Parser) {
  36     // Call the base implementation.
  37     this->MCAsmParserExtension::Initialize(Parser);
  38
  39     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveData>(".data");
  40     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveText>(".text");
  41     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveBSS>(".bss");
  42     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveRoData>(".rodata");
  43     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTData>(".tdata");
  44     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTBSS>(".tbss");
  45     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveDataRel>(".data.rel");
  46     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveDataRelRo>(".data.rel.ro");
  47     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveDataRelRoLocal>(".data.rel.ro.local");
  48     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveEhFrame>(".eh_frame");
  49     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSection>(".section");
  50     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSize>(".size");
  51     AddDirectiveHandler<&ELFAsmParser::ParseDirectivePrevious>(".previous");
  52   }
  53
  54   bool ParseSectionDirectiveData(StringRef, SMLoc) {
  55     return ParseSectionSwitch(".data", MCSectionELF::SHT_PROGBITS,
  56                               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
  57                               SectionKind::getDataRel());
  58   }
  59   bool ParseSectionDirectiveText(StringRef, SMLoc) {
  60     return ParseSectionSwitch(".text", MCSectionELF::SHT_PROGBITS,
  61                               MCSectionELF::SHF_EXECINSTR |
  62                               MCSectionELF::SHF_ALLOC, SectionKind::getText());
  63   }
  64   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
  65     return ParseSectionSwitch(".bss", MCSectionELF::SHT_NOBITS,
  66                               MCSectionELF::SHF_WRITE |
  67                               MCSectionELF::SHF_ALLOC, SectionKind::getBSS());
  68   }
  69   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
  70     return ParseSectionSwitch(".rodata", MCSectionELF::SHT_PROGBITS,
  71                               MCSectionELF::SHF_ALLOC,
  72                               SectionKind::getReadOnly());
  73   }
  74   bool ParseSectionDirectiveTData(StringRef, SMLoc) {
  75     return ParseSectionSwitch(".tdata", MCSectionELF::SHT_PROGBITS,
  76                               MCSectionELF::SHF_ALLOC |
  77                               MCSectionELF::SHF_TLS | MCSectionELF::SHF_WRITE,
  78                               SectionKind::getThreadData());
  79   }
  80   bool ParseSectionDirectiveTBSS(StringRef, SMLoc) {
  81     return ParseSectionSwitch(".tbss", MCSectionELF::SHT_NOBITS,
  82                               MCSectionELF::SHF_ALLOC |
  83                               MCSectionELF::SHF_TLS | MCSectionELF::SHF_WRITE,
  84                               SectionKind::getThreadBSS());
  85   }
  86   bool ParseSectionDirectiveDataRel(StringRef, SMLoc) {
  87     return ParseSectionSwitch(".data.rel", MCSectionELF::SHT_PROGBITS,
  88                               MCSectionELF::SHF_ALLOC |
  89                               MCSectionELF::SHF_WRITE,
  90                               SectionKind::getDataRel());
  91   }
  92   bool ParseSectionDirectiveDataRelRo(StringRef, SMLoc) {
  93     return ParseSectionSwitch(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
  94                               MCSectionELF::SHF_ALLOC |
  95                               MCSectionELF::SHF_WRITE,
  96                               SectionKind::getReadOnlyWithRel());
  97   }
  98   bool ParseSectionDirectiveDataRelRoLocal(StringRef, SMLoc) {
  99     return ParseSectionSwitch(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
 100                               MCSectionELF::SHF_ALLOC |
 101                               MCSectionELF::SHF_WRITE,
 102                               SectionKind::getReadOnlyWithRelLocal());
 103   }
 104   bool ParseSectionDirectiveEhFrame(StringRef, SMLoc) {
 105     return ParseSectionSwitch(".eh_frame", MCSectionELF::SHT_PROGBITS,
 106                               MCSectionELF::SHF_ALLOC |
 107                               MCSectionELF::SHF_WRITE,
 108                               SectionKind::getDataRel());
 109   }
 110   bool ParseDirectiveSection(StringRef, SMLoc);
 111   bool ParseDirectiveSize(StringRef, SMLoc);
 112   bool ParseDirectivePrevious(StringRef, SMLoc);
 113 };
 114
 115 }
 116
 117 bool ELFAsmParser::ParseSectionSwitch(StringRef Section, unsigned Type,
 118                                       unsigned Flags, SectionKind Kind) {
 119   if (getLexer().isNot(AsmToken::EndOfStatement))
 120     return TokError("unexpected token in section switching directive");
 121   Lex();
 122
 123   getStreamer().SwitchSection(getContext().getELFSection(
 124                                 Section, Type, Flags, Kind));
 125
 126   return false;
 127 }
 128
 129 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
 130   StringRef Name;
 131   if (getParser().ParseIdentifier(Name))
 132     return TokError("expected identifier in directive");
 133   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);;
 134
 135   if (getLexer().isNot(AsmToken::Comma))
 136     return TokError("unexpected token in directive");
 137   Lex();
 138
 139   const MCExpr *Expr;
 140   if (getParser().ParseExpression(Expr))
 141     return true;
 142
 143   if (getLexer().isNot(AsmToken::EndOfStatement))
 144     return TokError("unexpected token in directive");
 145
 146   getStreamer().EmitELFSize(Sym, Expr);
 147   return false;
 148 }
 149
 150 // FIXME: This is a work in progress.
 151 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) {
 152   StringRef SectionName;
 153   // FIXME: This doesn't parse section names like ".note.GNU-stack" correctly.
 154   if (getParser().ParseIdentifier(SectionName))
 155     return TokError("expected identifier in directive");
 156
 157   std::string FlagsStr;
 158   StringRef TypeName;
 159   int64_t Size = 0;
 160   if (getLexer().is(AsmToken::Comma)) {
 161     Lex();
 162
 163     if (getLexer().isNot(AsmToken::String))
 164       return TokError("expected string in directive");
 165
 166     FlagsStr = getTok().getStringContents();
 167     Lex();
 168
 169     AsmToken::TokenKind TypeStartToken;
 170     if (getContext().getAsmInfo().getCommentString()[0] == '@')
 171       TypeStartToken = AsmToken::Percent;
 172     else
 173       TypeStartToken = AsmToken::At;
 174
 175     if (getLexer().is(AsmToken::Comma)) {
 176       Lex();
 177       if (getLexer().is(TypeStartToken)) {
 178         Lex();
 179         if (getParser().ParseIdentifier(TypeName))
 180           return TokError("expected identifier in directive");
 181
 182         if (getLexer().is(AsmToken::Comma)) {
 183           Lex();
 184
 185           if (getParser().ParseAbsoluteExpression(Size))
 186             return true;
 187
 188           if (Size <= 0)
 189             return TokError("section size must be positive");
 190         }
 191       }
 192     }
 193   }
 194
 195   if (getLexer().isNot(AsmToken::EndOfStatement))
 196     return TokError("unexpected token in directive");
 197
 198   unsigned Flags = 0;
 199   for (unsigned i = 0; i < FlagsStr.size(); i++) {
 200     switch (FlagsStr[i]) {
 201     case 'a':
 202       Flags |= MCSectionELF::SHF_ALLOC;
 203       break;
 204     case 'x':
 205       Flags |= MCSectionELF::SHF_EXECINSTR;
 206       break;
 207     case 'w':
 208       Flags |= MCSectionELF::SHF_WRITE;
 209       break;
 210     case 'M':
 211       Flags |= MCSectionELF::SHF_MERGE;
 212       break;
 213     case 'S':
 214       Flags |= MCSectionELF::SHF_STRINGS;
 215       break;
 216     case 'T':
 217       Flags |= MCSectionELF::SHF_TLS;
 218       break;
 219     case 'c':
 220       Flags |= MCSectionELF::XCORE_SHF_CP_SECTION;
 221       break;
 222     case 'd':
 223       Flags |= MCSectionELF::XCORE_SHF_DP_SECTION;
 224       break;
 225     default:
 226       return TokError("unknown flag");
 227     }
 228   }
 229
 230   unsigned Type = MCSectionELF::SHT_NULL;
 231   if (!TypeName.empty()) {
 232     if (TypeName == "init_array")
 233       Type = MCSectionELF::SHT_INIT_ARRAY;
 234     else if (TypeName == "fini_array")
 235       Type = MCSectionELF::SHT_FINI_ARRAY;
 236     else if (TypeName == "preinit_array")
 237       Type = MCSectionELF::SHT_PREINIT_ARRAY;
 238     else if (TypeName == "nobits")
 239       Type = MCSectionELF::SHT_NOBITS;
 240     else if (TypeName == "progbits")
 241       Type = MCSectionELF::SHT_PROGBITS;
 242     else
 243       return TokError("unknown section type");
 244   }
 245
 246   SectionKind Kind = (Flags & MCSectionELF::SHF_EXECINSTR)
 247                      ? SectionKind::getText()
 248                      : SectionKind::getDataRel();
 249   getStreamer().SwitchSection(getContext().getELFSection(SectionName, Type,
 250                                                          Flags, Kind, false));
 251   return false;
 252 }
 253
 254 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
 255   const MCSection *PreviousSection = getStreamer().getPreviousSection();
 256   if (PreviousSection != NULL)
 257     getStreamer().SwitchSection(PreviousSection);
 258
 259   return false;
 260 }
 261
 262 namespace llvm {
 263
 264 MCAsmParserExtension *createELFAsmParser() {
 265   return new ELFAsmParser;
 266 }
 267
 268 }