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   // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
  55   // the best way for us to get access to it?
  56   bool ParseSectionDirectiveData(StringRef, SMLoc) {
  57     bool ret =  ParseSectionSwitch(".data", MCSectionELF::SHT_PROGBITS,
  58                               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
  59                               SectionKind::getDataRel());
  60     getStreamer().EmitCodeAlignment(4, 0);
  61     return ret;
  62   }
  63   bool ParseSectionDirectiveText(StringRef, SMLoc) {
  64     bool ret = ParseSectionSwitch(".text", MCSectionELF::SHT_PROGBITS,
  65                               MCSectionELF::SHF_EXECINSTR |
  66                               MCSectionELF::SHF_ALLOC, SectionKind::getText());
  67     getStreamer().EmitCodeAlignment(4, 0);
  68     return ret;
  69   }
  70   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
  71     bool ret = ParseSectionSwitch(".bss", MCSectionELF::SHT_NOBITS,
  72                               MCSectionELF::SHF_WRITE |
  73                               MCSectionELF::SHF_ALLOC, SectionKind::getBSS());
  74     getStreamer().EmitCodeAlignment(4, 0);
  75     return ret;
  76   }
  77   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
  78     return ParseSectionSwitch(".rodata", MCSectionELF::SHT_PROGBITS,
  79                               MCSectionELF::SHF_ALLOC,
  80                               SectionKind::getReadOnly());
  81   }
  82   bool ParseSectionDirectiveTData(StringRef, SMLoc) {
  83     return ParseSectionSwitch(".tdata", MCSectionELF::SHT_PROGBITS,
  84                               MCSectionELF::SHF_ALLOC |
  85                               MCSectionELF::SHF_TLS | MCSectionELF::SHF_WRITE,
  86                               SectionKind::getThreadData());
  87   }
  88   bool ParseSectionDirectiveTBSS(StringRef, SMLoc) {
  89     return ParseSectionSwitch(".tbss", MCSectionELF::SHT_NOBITS,
  90                               MCSectionELF::SHF_ALLOC |
  91                               MCSectionELF::SHF_TLS | MCSectionELF::SHF_WRITE,
  92                               SectionKind::getThreadBSS());
  93   }
  94   bool ParseSectionDirectiveDataRel(StringRef, SMLoc) {
  95     return ParseSectionSwitch(".data.rel", MCSectionELF::SHT_PROGBITS,
  96                               MCSectionELF::SHF_ALLOC |
  97                               MCSectionELF::SHF_WRITE,
  98                               SectionKind::getDataRel());
  99   }
 100   bool ParseSectionDirectiveDataRelRo(StringRef, SMLoc) {
 101     return ParseSectionSwitch(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
 102                               MCSectionELF::SHF_ALLOC |
 103                               MCSectionELF::SHF_WRITE,
 104                               SectionKind::getReadOnlyWithRel());
 105   }
 106   bool ParseSectionDirectiveDataRelRoLocal(StringRef, SMLoc) {
 107     return ParseSectionSwitch(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
 108                               MCSectionELF::SHF_ALLOC |
 109                               MCSectionELF::SHF_WRITE,
 110                               SectionKind::getReadOnlyWithRelLocal());
 111   }
 112   bool ParseSectionDirectiveEhFrame(StringRef, SMLoc) {
 113     return ParseSectionSwitch(".eh_frame", MCSectionELF::SHT_PROGBITS,
 114                               MCSectionELF::SHF_ALLOC |
 115                               MCSectionELF::SHF_WRITE,
 116                               SectionKind::getDataRel());
 117   }
 118   bool ParseDirectiveSection(StringRef, SMLoc);
 119   bool ParseDirectiveSize(StringRef, SMLoc);
 120   bool ParseDirectivePrevious(StringRef, SMLoc);
 121 };
 122
 123 }
 124
 125 bool ELFAsmParser::ParseSectionSwitch(StringRef Section, unsigned Type,
 126                                       unsigned Flags, SectionKind Kind) {
 127   if (getLexer().isNot(AsmToken::EndOfStatement))
 128     return TokError("unexpected token in section switching directive");
 129   Lex();
 130
 131   getStreamer().SwitchSection(getContext().getELFSection(
 132                                 Section, Type, Flags, Kind));
 133
 134   return false;
 135 }
 136
 137 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
 138   StringRef Name;
 139   if (getParser().ParseIdentifier(Name))
 140     return TokError("expected identifier in directive");
 141   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);;
 142
 143   if (getLexer().isNot(AsmToken::Comma))
 144     return TokError("unexpected token in directive");
 145   Lex();
 146
 147   const MCExpr *Expr;
 148   if (getParser().ParseExpression(Expr))
 149     return true;
 150
 151   if (getLexer().isNot(AsmToken::EndOfStatement))
 152     return TokError("unexpected token in directive");
 153
 154   getStreamer().EmitELFSize(Sym, Expr);
 155   return false;
 156 }
 157
 158 // FIXME: This is a work in progress.
 159 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) {
 160   StringRef SectionName;
 161   // FIXME: This doesn't parse section names like ".note.GNU-stack" correctly.
 162   if (getParser().ParseIdentifier(SectionName))
 163     return TokError("expected identifier in directive");
 164
 165   std::string FlagsStr;
 166   StringRef TypeName;
 167   int64_t Size = 0;
 168   if (getLexer().is(AsmToken::Comma)) {
 169     Lex();
 170
 171     if (getLexer().isNot(AsmToken::String))
 172       return TokError("expected string in directive");
 173
 174     FlagsStr = getTok().getStringContents();
 175     Lex();
 176
 177     AsmToken::TokenKind TypeStartToken;
 178     if (getContext().getAsmInfo().getCommentString()[0] == '@')
 179       TypeStartToken = AsmToken::Percent;
 180     else
 181       TypeStartToken = AsmToken::At;
 182
 183     if (getLexer().is(AsmToken::Comma)) {
 184       Lex();
 185       if (getLexer().is(TypeStartToken)) {
 186         Lex();
 187         if (getParser().ParseIdentifier(TypeName))
 188           return TokError("expected identifier in directive");
 189
 190         if (getLexer().is(AsmToken::Comma)) {
 191           Lex();
 192
 193           if (getParser().ParseAbsoluteExpression(Size))
 194             return true;
 195
 196           if (Size <= 0)
 197             return TokError("section size must be positive");
 198         }
 199       }
 200     }
 201   }
 202
 203   if (getLexer().isNot(AsmToken::EndOfStatement))
 204     return TokError("unexpected token in directive");
 205
 206   unsigned Flags = 0;
 207   for (unsigned i = 0; i < FlagsStr.size(); i++) {
 208     switch (FlagsStr[i]) {
 209     case 'a':
 210       Flags |= MCSectionELF::SHF_ALLOC;
 211       break;
 212     case 'x':
 213       Flags |= MCSectionELF::SHF_EXECINSTR;
 214       break;
 215     case 'w':
 216       Flags |= MCSectionELF::SHF_WRITE;
 217       break;
 218     case 'M':
 219       Flags |= MCSectionELF::SHF_MERGE;
 220       break;
 221     case 'S':
 222       Flags |= MCSectionELF::SHF_STRINGS;
 223       break;
 224     case 'T':
 225       Flags |= MCSectionELF::SHF_TLS;
 226       break;
 227     case 'c':
 228       Flags |= MCSectionELF::XCORE_SHF_CP_SECTION;
 229       break;
 230     case 'd':
 231       Flags |= MCSectionELF::XCORE_SHF_DP_SECTION;
 232       break;
 233     default:
 234       return TokError("unknown flag");
 235     }
 236   }
 237
 238   unsigned Type = MCSectionELF::SHT_NULL;
 239   if (!TypeName.empty()) {
 240     if (TypeName == "init_array")
 241       Type = MCSectionELF::SHT_INIT_ARRAY;
 242     else if (TypeName == "fini_array")
 243       Type = MCSectionELF::SHT_FINI_ARRAY;
 244     else if (TypeName == "preinit_array")
 245       Type = MCSectionELF::SHT_PREINIT_ARRAY;
 246     else if (TypeName == "nobits")
 247       Type = MCSectionELF::SHT_NOBITS;
 248     else if (TypeName == "progbits")
 249       Type = MCSectionELF::SHT_PROGBITS;
 250     else
 251       return TokError("unknown section type");
 252   }
 253
 254   SectionKind Kind = (Flags & MCSectionELF::SHF_EXECINSTR)
 255                      ? SectionKind::getText()
 256                      : SectionKind::getDataRel();
 257   getStreamer().SwitchSection(getContext().getELFSection(SectionName, Type,
 258                                                          Flags, Kind, false));
 259   return false;
 260 }
 261
 262 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
 263   const MCSection *PreviousSection = getStreamer().getPreviousSection();
 264   if (PreviousSection != NULL)
 265     getStreamer().SwitchSection(PreviousSection);
 266
 267   return false;
 268 }
 269
 270 namespace llvm {
 271
 272 MCAsmParserExtension *createELFAsmParser() {
 273   return new ELFAsmParser;
 274 }
 275
 276 }