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/StringSwitch.h"
  12 #include "llvm/ADT/Twine.h"
  13 #include "llvm/MC/MCAsmInfo.h"
  14 #include "llvm/MC/MCContext.h"
  15 #include "llvm/MC/MCExpr.h"
  16 #include "llvm/MC/MCParser/MCAsmLexer.h"
  17 #include "llvm/MC/MCSectionELF.h"
  18 #include "llvm/MC/MCStreamer.h"
  19 using namespace llvm;
  20
  21 namespace {
  22
  23 class ELFAsmParser : public MCAsmParserExtension {
  24   template<bool (ELFAsmParser::*Handler)(StringRef, SMLoc)>
  25   void AddDirectiveHandler(StringRef Directive) {
  26     getParser().AddDirectiveHandler(this, Directive,
  27                                     HandleDirective<ELFAsmParser, Handler>);
  28   }
  29
  30   bool ParseSectionSwitch(StringRef Section, unsigned Type,
  31                           unsigned Flags, SectionKind Kind);
  32
  33 public:
  34   ELFAsmParser() {}
  35
  36   virtual void Initialize(MCAsmParser &Parser) {
  37     // Call the base implementation.
  38     this->MCAsmParserExtension::Initialize(Parser);
  39
  40     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveData>(".data");
  41     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveText>(".text");
  42     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveBSS>(".bss");
  43     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveRoData>(".rodata");
  44     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTData>(".tdata");
  45     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTBSS>(".tbss");
  46     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveDataRel>(".data.rel");
  47     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveDataRelRo>(".data.rel.ro");
  48     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveDataRelRoLocal>(".data.rel.ro.local");
  49     AddDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveEhFrame>(".eh_frame");
  50     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSection>(".section");
  51     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSize>(".size");
  52     AddDirectiveHandler<&ELFAsmParser::ParseDirectivePrevious>(".previous");
  53     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveType>(".type");
  54     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveIdent>(".ident");
  55     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveSymver>(".symver");
  56     AddDirectiveHandler<&ELFAsmParser::ParseDirectiveWeakref>(".weakref");
  57   }
  58
  59   // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
  60   // the best way for us to get access to it?
  61   bool ParseSectionDirectiveData(StringRef, SMLoc) {
  62     return ParseSectionSwitch(".data", MCSectionELF::SHT_PROGBITS,
  63                               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
  64                               SectionKind::getDataRel());
  65   }
  66   bool ParseSectionDirectiveText(StringRef, SMLoc) {
  67     return ParseSectionSwitch(".text", MCSectionELF::SHT_PROGBITS,
  68                               MCSectionELF::SHF_EXECINSTR |
  69                               MCSectionELF::SHF_ALLOC, SectionKind::getText());
  70   }
  71   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
  72     return ParseSectionSwitch(".bss", MCSectionELF::SHT_NOBITS,
  73                               MCSectionELF::SHF_WRITE |
  74                               MCSectionELF::SHF_ALLOC, SectionKind::getBSS());
  75   }
  76   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
  77     return ParseSectionSwitch(".rodata", MCSectionELF::SHT_PROGBITS,
  78                               MCSectionELF::SHF_ALLOC,
  79                               SectionKind::getReadOnly());
  80   }
  81   bool ParseSectionDirectiveTData(StringRef, SMLoc) {
  82     return ParseSectionSwitch(".tdata", MCSectionELF::SHT_PROGBITS,
  83                               MCSectionELF::SHF_ALLOC |
  84                               MCSectionELF::SHF_TLS | MCSectionELF::SHF_WRITE,
  85                               SectionKind::getThreadData());
  86   }
  87   bool ParseSectionDirectiveTBSS(StringRef, SMLoc) {
  88     return ParseSectionSwitch(".tbss", MCSectionELF::SHT_NOBITS,
  89                               MCSectionELF::SHF_ALLOC |
  90                               MCSectionELF::SHF_TLS | MCSectionELF::SHF_WRITE,
  91                               SectionKind::getThreadBSS());
  92   }
  93   bool ParseSectionDirectiveDataRel(StringRef, SMLoc) {
  94     return ParseSectionSwitch(".data.rel", MCSectionELF::SHT_PROGBITS,
  95                               MCSectionELF::SHF_ALLOC |
  96                               MCSectionELF::SHF_WRITE,
  97                               SectionKind::getDataRel());
  98   }
  99   bool ParseSectionDirectiveDataRelRo(StringRef, SMLoc) {
 100     return ParseSectionSwitch(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
 101                               MCSectionELF::SHF_ALLOC |
 102                               MCSectionELF::SHF_WRITE,
 103                               SectionKind::getReadOnlyWithRel());
 104   }
 105   bool ParseSectionDirectiveDataRelRoLocal(StringRef, SMLoc) {
 106     return ParseSectionSwitch(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
 107                               MCSectionELF::SHF_ALLOC |
 108                               MCSectionELF::SHF_WRITE,
 109                               SectionKind::getReadOnlyWithRelLocal());
 110   }
 111   bool ParseSectionDirectiveEhFrame(StringRef, SMLoc) {
 112     return ParseSectionSwitch(".eh_frame", MCSectionELF::SHT_PROGBITS,
 113                               MCSectionELF::SHF_ALLOC |
 114                               MCSectionELF::SHF_WRITE,
 115                               SectionKind::getDataRel());
 116   }
 117   bool ParseDirectiveSection(StringRef, SMLoc);
 118   bool ParseDirectiveSize(StringRef, SMLoc);
 119   bool ParseDirectivePrevious(StringRef, SMLoc);
 120   bool ParseDirectiveType(StringRef, SMLoc);
 121   bool ParseDirectiveIdent(StringRef, SMLoc);
 122   bool ParseDirectiveSymver(StringRef, SMLoc);
 123   bool ParseDirectiveWeakref(StringRef, SMLoc);
 124
 125 private:
 126   bool ParseSectionName(StringRef &SectionName);
 127 };
 128
 129 }
 130
 131 bool ELFAsmParser::ParseSectionSwitch(StringRef Section, unsigned Type,
 132                                       unsigned Flags, SectionKind Kind) {
 133   if (getLexer().isNot(AsmToken::EndOfStatement))
 134     return TokError("unexpected token in section switching directive");
 135   Lex();
 136
 137   getStreamer().SwitchSection(getContext().getELFSection(
 138                                 Section, Type, Flags, Kind));
 139
 140   return false;
 141 }
 142
 143 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
 144   StringRef Name;
 145   if (getParser().ParseIdentifier(Name))
 146     return TokError("expected identifier in directive");
 147   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);;
 148
 149   if (getLexer().isNot(AsmToken::Comma))
 150     return TokError("unexpected token in directive");
 151   Lex();
 152
 153   const MCExpr *Expr;
 154   if (getParser().ParseExpression(Expr))
 155     return true;
 156
 157   if (getLexer().isNot(AsmToken::EndOfStatement))
 158     return TokError("unexpected token in directive");
 159
 160   getStreamer().EmitELFSize(Sym, Expr);
 161   return false;
 162 }
 163
 164 bool ELFAsmParser::ParseSectionName(StringRef &SectionName) {
 165   // A section name can contain -, so we cannot just use
 166   // ParseIdentifier.
 167   SMLoc FirstLoc = getLexer().getLoc();
 168   unsigned Size = 0;
 169
 170   for (;;) {
 171     StringRef Tmp;
 172     unsigned CurSize;
 173
 174     SMLoc PrevLoc = getLexer().getLoc();
 175     if (getLexer().is(AsmToken::Minus)) {
 176       CurSize = 1;
 177       Lex(); // Consume the "-".
 178     } else if (!getParser().ParseIdentifier(Tmp))
 179       CurSize = Tmp.size();
 180     else
 181       break;
 182
 183     Size += CurSize;
 184     SectionName = StringRef(FirstLoc.getPointer(), Size);
 185
 186     // Make sure the following token is adjacent.
 187     if (PrevLoc.getPointer() + CurSize != getTok().getLoc().getPointer())
 188       break;
 189   }
 190   if (Size == 0)
 191     return true;
 192
 193   return false;
 194 }
 195
 196 // FIXME: This is a work in progress.
 197 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc) {
 198   StringRef SectionName;
 199
 200   if (ParseSectionName(SectionName))
 201     return TokError("expected identifier in directive");
 202
 203   StringRef FlagsStr;
 204   StringRef TypeName;
 205   int64_t Size = 0;
 206   if (getLexer().is(AsmToken::Comma)) {
 207     Lex();
 208
 209     if (getLexer().isNot(AsmToken::String))
 210       return TokError("expected string in directive");
 211
 212     FlagsStr = getTok().getStringContents();
 213     Lex();
 214
 215     AsmToken::TokenKind TypeStartToken;
 216     if (getContext().getAsmInfo().getCommentString()[0] == '@')
 217       TypeStartToken = AsmToken::Percent;
 218     else
 219       TypeStartToken = AsmToken::At;
 220
 221     bool Mergeable = FlagsStr.find('M') != StringRef::npos;
 222     bool Group = FlagsStr.find('G') != StringRef::npos;
 223
 224     if (getLexer().isNot(AsmToken::Comma)) {
 225       if (Mergeable)
 226         return TokError("Mergeable section must specify the type");
 227       if (Group)
 228         return TokError("Group section must specify the type");
 229     } else {
 230       Lex();
 231       if (getLexer().isNot(TypeStartToken))
 232         return TokError("expected the type");
 233
 234       Lex();
 235       if (getParser().ParseIdentifier(TypeName))
 236         return TokError("expected identifier in directive");
 237
 238       if (Mergeable) {
 239         if (getLexer().isNot(AsmToken::Comma))
 240           return TokError("expected the entry size");
 241         Lex();
 242         if (getParser().ParseAbsoluteExpression(Size))
 243           return true;
 244         if (Size <= 0)
 245           return TokError("entry size must be positive");
 246       }
 247
 248       if (Group) {
 249         if (getLexer().isNot(AsmToken::Comma))
 250           return TokError("expected group name");
 251         Lex();
 252         StringRef GroupName;
 253         if (getParser().ParseIdentifier(GroupName))
 254           return true;
 255         if (getLexer().is(AsmToken::Comma)) {
 256           Lex();
 257           StringRef Linkage;
 258           if (getParser().ParseIdentifier(Linkage))
 259             return true;
 260           if (Linkage != "comdat" && Linkage != ".gnu.linkonce")
 261             return TokError("Linkage must be 'comdat' or '.gnu.linkonce'");
 262         }
 263       }
 264     }
 265   }
 266
 267   if (getLexer().isNot(AsmToken::EndOfStatement))
 268     return TokError("unexpected token in directive");
 269
 270   unsigned Flags = 0;
 271   unsigned Type = MCSectionELF::SHT_NULL;
 272
 273   // Set the defaults first.
 274   if (SectionName == ".fini" || SectionName == ".init") {
 275     Type = MCSectionELF::SHT_PROGBITS;
 276     Flags |= MCSectionELF::SHF_ALLOC;
 277     Flags |= MCSectionELF::SHF_EXECINSTR;
 278   }
 279
 280   for (unsigned i = 0; i < FlagsStr.size(); i++) {
 281     switch (FlagsStr[i]) {
 282     case 'a':
 283       Flags |= MCSectionELF::SHF_ALLOC;
 284       break;
 285     case 'x':
 286       Flags |= MCSectionELF::SHF_EXECINSTR;
 287       break;
 288     case 'w':
 289       Flags |= MCSectionELF::SHF_WRITE;
 290       break;
 291     case 'M':
 292       Flags |= MCSectionELF::SHF_MERGE;
 293       break;
 294     case 'S':
 295       Flags |= MCSectionELF::SHF_STRINGS;
 296       break;
 297     case 'T':
 298       Flags |= MCSectionELF::SHF_TLS;
 299       break;
 300     case 'c':
 301       Flags |= MCSectionELF::XCORE_SHF_CP_SECTION;
 302       break;
 303     case 'd':
 304       Flags |= MCSectionELF::XCORE_SHF_DP_SECTION;
 305       break;
 306     case 'G':
 307       break;
 308     default:
 309       return TokError("unknown flag");
 310     }
 311   }
 312
 313   if (!TypeName.empty()) {
 314     if (TypeName == "init_array")
 315       Type = MCSectionELF::SHT_INIT_ARRAY;
 316     else if (TypeName == "fini_array")
 317       Type = MCSectionELF::SHT_FINI_ARRAY;
 318     else if (TypeName == "preinit_array")
 319       Type = MCSectionELF::SHT_PREINIT_ARRAY;
 320     else if (TypeName == "nobits")
 321       Type = MCSectionELF::SHT_NOBITS;
 322     else if (TypeName == "progbits")
 323       Type = MCSectionELF::SHT_PROGBITS;
 324     else
 325       return TokError("unknown section type");
 326   }
 327
 328   SectionKind Kind = (Flags & MCSectionELF::SHF_EXECINSTR)
 329                      ? SectionKind::getText()
 330                      : SectionKind::getDataRel();
 331   getStreamer().SwitchSection(getContext().getELFSection(SectionName, Type,
 332                                                          Flags, Kind, false,
 333                                                          Size));
 334   return false;
 335 }
 336
 337 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
 338   const MCSection *PreviousSection = getStreamer().getPreviousSection();
 339   if (PreviousSection != NULL)
 340     getStreamer().SwitchSection(PreviousSection);
 341
 342   return false;
 343 }
 344
 345 /// ParseDirectiveELFType
 346 ///  ::= .type identifier , @attribute
 347 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
 348   StringRef Name;
 349   if (getParser().ParseIdentifier(Name))
 350     return TokError("expected identifier in directive");
 351
 352   // Handle the identifier as the key symbol.
 353   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
 354
 355   if (getLexer().isNot(AsmToken::Comma))
 356     return TokError("unexpected token in '.type' directive");
 357   Lex();
 358
 359   if (getLexer().isNot(AsmToken::At))
 360     return TokError("expected '@' before type");
 361   Lex();
 362
 363   StringRef Type;
 364   SMLoc TypeLoc;
 365
 366   TypeLoc = getLexer().getLoc();
 367   if (getParser().ParseIdentifier(Type))
 368     return TokError("expected symbol type in directive");
 369
 370   MCSymbolAttr Attr = StringSwitch<MCSymbolAttr>(Type)
 371     .Case("function", MCSA_ELF_TypeFunction)
 372     .Case("object", MCSA_ELF_TypeObject)
 373     .Case("tls_object", MCSA_ELF_TypeTLS)
 374     .Case("common", MCSA_ELF_TypeCommon)
 375     .Case("notype", MCSA_ELF_TypeNoType)
 376     .Default(MCSA_Invalid);
 377
 378   if (Attr == MCSA_Invalid)
 379     return Error(TypeLoc, "unsupported attribute in '.type' directive");
 380
 381   if (getLexer().isNot(AsmToken::EndOfStatement))
 382     return TokError("unexpected token in '.type' directive");
 383
 384   Lex();
 385
 386   getStreamer().EmitSymbolAttribute(Sym, Attr);
 387
 388   return false;
 389 }
 390
 391 /// ParseDirectiveIdent
 392 ///  ::= .ident string
 393 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
 394   if (getLexer().isNot(AsmToken::String))
 395     return TokError("unexpected token in '.ident' directive");
 396
 397   StringRef Data = getTok().getIdentifier();
 398
 399   Lex();
 400
 401   const MCSection *OldSection = getStreamer().getCurrentSection();
 402   const MCSection *Comment =
 403     getContext().getELFSection(".comment", MCSectionELF::SHT_PROGBITS,
 404                                MCSectionELF::SHF_MERGE |
 405                                MCSectionELF::SHF_STRINGS,
 406                                SectionKind::getReadOnly(),
 407                                false, 1);
 408
 409   static bool First = true;
 410
 411   getStreamer().SwitchSection(Comment);
 412   if (First)
 413     getStreamer().EmitIntValue(0, 1);
 414   First = false;
 415   getStreamer().EmitBytes(Data, 0);
 416   getStreamer().EmitIntValue(0, 1);
 417   getStreamer().SwitchSection(OldSection);
 418   return false;
 419 }
 420
 421 /// ParseDirectiveSymver
 422 ///  ::= .symver foo, bar2@zed
 423 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
 424   StringRef Name;
 425   if (getParser().ParseIdentifier(Name))
 426     return TokError("expected identifier in directive");
 427
 428   if (getLexer().isNot(AsmToken::Comma))
 429     return TokError("expected a comma");
 430
 431   Lex();
 432
 433   StringRef AliasName;
 434   if (getParser().ParseIdentifier(AliasName))
 435     return TokError("expected identifier in directive");
 436
 437   if (AliasName.find('@') == StringRef::npos)
 438     return TokError("expected a '@' in the name");
 439
 440   MCSymbol *Alias = getContext().GetOrCreateSymbol(AliasName);
 441   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
 442   const MCExpr *Value = MCSymbolRefExpr::Create(Sym, getContext());
 443
 444   getStreamer().EmitAssignment(Alias, Value);
 445   return false;
 446 }
 447
 448 /// ParseDirectiveWeakref
 449 ///  ::= .weakref foo, bar
 450 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
 451   // FIXME: Share code with the other alias building directives.
 452
 453   StringRef AliasName;
 454   if (getParser().ParseIdentifier(AliasName))
 455     return TokError("expected identifier in directive");
 456
 457   if (getLexer().isNot(AsmToken::Comma))
 458     return TokError("expected a comma");
 459
 460   Lex();
 461
 462   StringRef Name;
 463   if (getParser().ParseIdentifier(Name))
 464     return TokError("expected identifier in directive");
 465
 466   MCSymbol *Alias = getContext().GetOrCreateSymbol(AliasName);
 467
 468   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
 469
 470   getStreamer().EmitWeakReference(Alias, Sym);
 471   return false;
 472 }
 473
 474 namespace llvm {
 475
 476 MCAsmParserExtension *createELFAsmParser() {
 477   return new ELFAsmParser;
 478 }
 479
 480 }