Home | History | Annotate | Download | only in MCParser 
      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 #include "llvm/MC/MCSymbol.h"
     20 #include "llvm/Support/ELF.h"
     21 using namespace llvm;
     22 
     23 namespace {
     24 
     25 class ELFAsmParser : public MCAsmParserExtension {
     26   template<bool (ELFAsmParser::*HandlerMethod)(StringRef, SMLoc)>
     27   void addDirectiveHandler(StringRef Directive) {
     28     MCAsmParser::ExtensionDirectiveHandler Handler = std::make_pair(
     29         this, HandleDirective<ELFAsmParser, HandlerMethod>);
     30 
     31     getParser().addDirectiveHandler(Directive, Handler);
     32   }
     33 
     34   bool ParseSectionSwitch(StringRef Section, unsigned Type, unsigned Flags,
     35                           SectionKind Kind);
     36 
     37 public:
     38   ELFAsmParser() { BracketExpressionsSupported = true; }
     39 
     40   void Initialize(MCAsmParser &Parser) override {
     41     // Call the base implementation.
     42     this->MCAsmParserExtension::Initialize(Parser);
     43 
     44     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveData>(".data");
     45     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveText>(".text");
     46     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveBSS>(".bss");
     47     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveRoData>(".rodata");
     48     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTData>(".tdata");
     49     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTBSS>(".tbss");
     50     addDirectiveHandler<
     51       &ELFAsmParser::ParseSectionDirectiveDataRel>(".data.rel");
     52     addDirectiveHandler<
     53       &ELFAsmParser::ParseSectionDirectiveDataRelRo>(".data.rel.ro");
     54     addDirectiveHandler<
     55       &ELFAsmParser::ParseSectionDirectiveDataRelRoLocal>(".data.rel.ro.local");
     56     addDirectiveHandler<
     57       &ELFAsmParser::ParseSectionDirectiveEhFrame>(".eh_frame");
     58     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSection>(".section");
     59     addDirectiveHandler<
     60       &ELFAsmParser::ParseDirectivePushSection>(".pushsection");
     61     addDirectiveHandler<&ELFAsmParser::ParseDirectivePopSection>(".popsection");
     62     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSize>(".size");
     63     addDirectiveHandler<&ELFAsmParser::ParseDirectivePrevious>(".previous");
     64     addDirectiveHandler<&ELFAsmParser::ParseDirectiveType>(".type");
     65     addDirectiveHandler<&ELFAsmParser::ParseDirectiveIdent>(".ident");
     66     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymver>(".symver");
     67     addDirectiveHandler<&ELFAsmParser::ParseDirectiveVersion>(".version");
     68     addDirectiveHandler<&ELFAsmParser::ParseDirectiveWeakref>(".weakref");
     69     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".weak");
     70     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".local");
     71     addDirectiveHandler<
     72       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".protected");
     73     addDirectiveHandler<
     74       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".internal");
     75     addDirectiveHandler<
     76       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".hidden");
     77     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSubsection>(".subsection");
     78   }
     79 
     80   // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
     81   // the best way for us to get access to it?
     82   bool ParseSectionDirectiveData(StringRef, SMLoc) {
     83     return ParseSectionSwitch(".data", ELF::SHT_PROGBITS,
     84                               ELF::SHF_WRITE |ELF::SHF_ALLOC,
     85                               SectionKind::getDataRel());
     86   }
     87   bool ParseSectionDirectiveText(StringRef, SMLoc) {
     88     return ParseSectionSwitch(".text", ELF::SHT_PROGBITS,
     89                               ELF::SHF_EXECINSTR |
     90                               ELF::SHF_ALLOC, SectionKind::getText());
     91   }
     92   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
     93     return ParseSectionSwitch(".bss", ELF::SHT_NOBITS,
     94                               ELF::SHF_WRITE |
     95                               ELF::SHF_ALLOC, SectionKind::getBSS());
     96   }
     97   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
     98     return ParseSectionSwitch(".rodata", ELF::SHT_PROGBITS,
     99                               ELF::SHF_ALLOC,
    100                               SectionKind::getReadOnly());
    101   }
    102   bool ParseSectionDirectiveTData(StringRef, SMLoc) {
    103     return ParseSectionSwitch(".tdata", ELF::SHT_PROGBITS,
    104                               ELF::SHF_ALLOC |
    105                               ELF::SHF_TLS | ELF::SHF_WRITE,
    106                               SectionKind::getThreadData());
    107   }
    108   bool ParseSectionDirectiveTBSS(StringRef, SMLoc) {
    109     return ParseSectionSwitch(".tbss", ELF::SHT_NOBITS,
    110                               ELF::SHF_ALLOC |
    111                               ELF::SHF_TLS | ELF::SHF_WRITE,
    112                               SectionKind::getThreadBSS());
    113   }
    114   bool ParseSectionDirectiveDataRel(StringRef, SMLoc) {
    115     return ParseSectionSwitch(".data.rel", ELF::SHT_PROGBITS,
    116                               ELF::SHF_ALLOC |
    117                               ELF::SHF_WRITE,
    118                               SectionKind::getDataRel());
    119   }
    120   bool ParseSectionDirectiveDataRelRo(StringRef, SMLoc) {
    121     return ParseSectionSwitch(".data.rel.ro", ELF::SHT_PROGBITS,
    122                               ELF::SHF_ALLOC |
    123                               ELF::SHF_WRITE,
    124                               SectionKind::getReadOnlyWithRel());
    125   }
    126   bool ParseSectionDirectiveDataRelRoLocal(StringRef, SMLoc) {
    127     return ParseSectionSwitch(".data.rel.ro.local", ELF::SHT_PROGBITS,
    128                               ELF::SHF_ALLOC |
    129                               ELF::SHF_WRITE,
    130                               SectionKind::getReadOnlyWithRelLocal());
    131   }
    132   bool ParseSectionDirectiveEhFrame(StringRef, SMLoc) {
    133     return ParseSectionSwitch(".eh_frame", ELF::SHT_PROGBITS,
    134                               ELF::SHF_ALLOC |
    135                               ELF::SHF_WRITE,
    136                               SectionKind::getDataRel());
    137   }
    138   bool ParseDirectivePushSection(StringRef, SMLoc);
    139   bool ParseDirectivePopSection(StringRef, SMLoc);
    140   bool ParseDirectiveSection(StringRef, SMLoc);
    141   bool ParseDirectiveSize(StringRef, SMLoc);
    142   bool ParseDirectivePrevious(StringRef, SMLoc);
    143   bool ParseDirectiveType(StringRef, SMLoc);
    144   bool ParseDirectiveIdent(StringRef, SMLoc);
    145   bool ParseDirectiveSymver(StringRef, SMLoc);
    146   bool ParseDirectiveVersion(StringRef, SMLoc);
    147   bool ParseDirectiveWeakref(StringRef, SMLoc);
    148   bool ParseDirectiveSymbolAttribute(StringRef, SMLoc);
    149   bool ParseDirectiveSubsection(StringRef, SMLoc);
    150 
    151 private:
    152   bool ParseSectionName(StringRef &SectionName);
    153   bool ParseSectionArguments(bool IsPush, SMLoc loc);
    154   unsigned parseSunStyleSectionFlags();
    155 };
    156 
    157 }
    158 
    159 /// ParseDirectiveSymbolAttribute
    160 ///  ::= { ".local", ".weak", ... } [ identifier ( , identifier )* ]
    161 bool ELFAsmParser::ParseDirectiveSymbolAttribute(StringRef Directive, SMLoc) {
    162   MCSymbolAttr Attr = StringSwitch<MCSymbolAttr>(Directive)
    163     .Case(".weak", MCSA_Weak)
    164     .Case(".local", MCSA_Local)
    165     .Case(".hidden", MCSA_Hidden)
    166     .Case(".internal", MCSA_Internal)
    167     .Case(".protected", MCSA_Protected)
    168     .Default(MCSA_Invalid);
    169   assert(Attr != MCSA_Invalid && "unexpected symbol attribute directive!");
    170   if (getLexer().isNot(AsmToken::EndOfStatement)) {
    171     for (;;) {
    172       StringRef Name;
    173 
    174       if (getParser().parseIdentifier(Name))
    175         return TokError("expected identifier in directive");
    176 
    177       MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
    178 
    179       getStreamer().EmitSymbolAttribute(Sym, Attr);
    180 
    181       if (getLexer().is(AsmToken::EndOfStatement))
    182         break;
    183 
    184       if (getLexer().isNot(AsmToken::Comma))
    185         return TokError("unexpected token in directive");
    186       Lex();
    187     }
    188   }
    189 
    190   Lex();
    191   return false;
    192 }
    193 
    194 bool ELFAsmParser::ParseSectionSwitch(StringRef Section, unsigned Type,
    195                                       unsigned Flags, SectionKind Kind) {
    196   const MCExpr *Subsection = nullptr;
    197   if (getLexer().isNot(AsmToken::EndOfStatement)) {
    198     if (getParser().parseExpression(Subsection))
    199       return true;
    200   }
    201 
    202   getStreamer().SwitchSection(getContext().getELFSection(
    203                                 Section, Type, Flags, Kind),
    204                               Subsection);
    205 
    206   return false;
    207 }
    208 
    209 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
    210   StringRef Name;
    211   if (getParser().parseIdentifier(Name))
    212     return TokError("expected identifier in directive");
    213   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
    214 
    215   if (getLexer().isNot(AsmToken::Comma))
    216     return TokError("unexpected token in directive");
    217   Lex();
    218 
    219   const MCExpr *Expr;
    220   if (getParser().parseExpression(Expr))
    221     return true;
    222 
    223   if (getLexer().isNot(AsmToken::EndOfStatement))
    224     return TokError("unexpected token in directive");
    225 
    226   getStreamer().EmitELFSize(Sym, Expr);
    227   return false;
    228 }
    229 
    230 bool ELFAsmParser::ParseSectionName(StringRef &SectionName) {
    231   // A section name can contain -, so we cannot just use
    232   // parseIdentifier.
    233   SMLoc FirstLoc = getLexer().getLoc();
    234   unsigned Size = 0;
    235 
    236   if (getLexer().is(AsmToken::String)) {
    237     SectionName = getTok().getIdentifier();
    238     Lex();
    239     return false;
    240   }
    241 
    242   for (;;) {
    243     unsigned CurSize;
    244 
    245     SMLoc PrevLoc = getLexer().getLoc();
    246     if (getLexer().is(AsmToken::Minus)) {
    247       CurSize = 1;
    248       Lex(); // Consume the "-".
    249     } else if (getLexer().is(AsmToken::String)) {
    250       CurSize = getTok().getIdentifier().size() + 2;
    251       Lex();
    252     } else if (getLexer().is(AsmToken::Identifier)) {
    253       CurSize = getTok().getIdentifier().size();
    254       Lex();
    255     } else {
    256       break;
    257     }
    258 
    259     Size += CurSize;
    260     SectionName = StringRef(FirstLoc.getPointer(), Size);
    261 
    262     // Make sure the following token is adjacent.
    263     if (PrevLoc.getPointer() + CurSize != getTok().getLoc().getPointer())
    264       break;
    265   }
    266   if (Size == 0)
    267     return true;
    268 
    269   return false;
    270 }
    271 
    272 static SectionKind computeSectionKind(unsigned Flags, unsigned ElemSize) {
    273   if (Flags & ELF::SHF_EXECINSTR)
    274     return SectionKind::getText();
    275   if (Flags & ELF::SHF_TLS)
    276     return SectionKind::getThreadData();
    277   if (Flags & ELF::SHF_MERGE) {
    278     if (Flags & ELF::SHF_STRINGS) {
    279       switch (ElemSize) {
    280       default:
    281         break;
    282       case 1:
    283         return SectionKind::getMergeable1ByteCString();
    284       case 2:
    285         return SectionKind::getMergeable2ByteCString();
    286       case 4:
    287         return SectionKind::getMergeable4ByteCString();
    288       }
    289     } else {
    290       switch (ElemSize) {
    291       default:
    292         break;
    293       case 4:
    294         return SectionKind::getMergeableConst4();
    295       case 8:
    296         return SectionKind::getMergeableConst8();
    297       case 16:
    298         return SectionKind::getMergeableConst16();
    299       }
    300     }
    301   }
    302 
    303   return SectionKind::getDataRel();
    304 }
    305 
    306 static unsigned parseSectionFlags(StringRef flagsStr, bool *UseLastGroup) {
    307   unsigned flags = 0;
    308 
    309   for (unsigned i = 0; i < flagsStr.size(); i++) {
    310     switch (flagsStr[i]) {
    311     case 'a':
    312       flags |= ELF::SHF_ALLOC;
    313       break;
    314     case 'e':
    315       flags |= ELF::SHF_EXCLUDE;
    316       break;
    317     case 'x':
    318       flags |= ELF::SHF_EXECINSTR;
    319       break;
    320     case 'w':
    321       flags |= ELF::SHF_WRITE;
    322       break;
    323     case 'M':
    324       flags |= ELF::SHF_MERGE;
    325       break;
    326     case 'S':
    327       flags |= ELF::SHF_STRINGS;
    328       break;
    329     case 'T':
    330       flags |= ELF::SHF_TLS;
    331       break;
    332     case 'c':
    333       flags |= ELF::XCORE_SHF_CP_SECTION;
    334       break;
    335     case 'd':
    336       flags |= ELF::XCORE_SHF_DP_SECTION;
    337       break;
    338     case 'G':
    339       flags |= ELF::SHF_GROUP;
    340       break;
    341     case '?':
    342       *UseLastGroup = true;
    343       break;
    344     default:
    345       return -1U;
    346     }
    347   }
    348 
    349   return flags;
    350 }
    351 
    352 unsigned ELFAsmParser::parseSunStyleSectionFlags() {
    353   unsigned flags = 0;
    354   while (getLexer().is(AsmToken::Hash)) {
    355     Lex(); // Eat the #.
    356 
    357     if (!getLexer().is(AsmToken::Identifier))
    358       return -1U;
    359 
    360     StringRef flagId = getTok().getIdentifier();
    361     if (flagId == "alloc")
    362       flags |= ELF::SHF_ALLOC;
    363     else if (flagId == "execinstr")
    364       flags |= ELF::SHF_EXECINSTR;
    365     else if (flagId == "write")
    366       flags |= ELF::SHF_WRITE;
    367     else if (flagId == "tls")
    368       flags |= ELF::SHF_TLS;
    369     else
    370       return -1U;
    371 
    372     Lex(); // Eat the flag.
    373 
    374     if (!getLexer().is(AsmToken::Comma))
    375         break;
    376     Lex(); // Eat the comma.
    377   }
    378   return flags;
    379 }
    380 
    381 
    382 bool ELFAsmParser::ParseDirectivePushSection(StringRef s, SMLoc loc) {
    383   getStreamer().PushSection();
    384 
    385   if (ParseSectionArguments(/*IsPush=*/true, loc)) {
    386     getStreamer().PopSection();
    387     return true;
    388   }
    389 
    390   return false;
    391 }
    392 
    393 bool ELFAsmParser::ParseDirectivePopSection(StringRef, SMLoc) {
    394   if (!getStreamer().PopSection())
    395     return TokError(".popsection without corresponding .pushsection");
    396   return false;
    397 }
    398 
    399 // FIXME: This is a work in progress.
    400 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc loc) {
    401   return ParseSectionArguments(/*IsPush=*/false, loc);
    402 }
    403 
    404 bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
    405   StringRef SectionName;
    406 
    407   if (ParseSectionName(SectionName))
    408     return TokError("expected identifier in directive");
    409 
    410   StringRef TypeName;
    411   int64_t Size = 0;
    412   StringRef GroupName;
    413   unsigned Flags = 0;
    414   const MCExpr *Subsection = nullptr;
    415   bool UseLastGroup = false;
    416 
    417   // Set the defaults first.
    418   if (SectionName == ".fini" || SectionName == ".init" ||
    419       SectionName == ".rodata")
    420     Flags |= ELF::SHF_ALLOC;
    421   if (SectionName == ".fini" || SectionName == ".init")
    422     Flags |= ELF::SHF_EXECINSTR;
    423 
    424   if (getLexer().is(AsmToken::Comma)) {
    425     Lex();
    426 
    427     if (IsPush && getLexer().isNot(AsmToken::String)) {
    428       if (getParser().parseExpression(Subsection))
    429         return true;
    430       if (getLexer().isNot(AsmToken::Comma))
    431         goto EndStmt;
    432       Lex();
    433     }
    434 
    435     unsigned extraFlags;
    436 
    437     if (getLexer().isNot(AsmToken::String)) {
    438       if (!getContext().getAsmInfo()->usesSunStyleELFSectionSwitchSyntax()
    439           || getLexer().isNot(AsmToken::Hash))
    440         return TokError("expected string in directive");
    441       extraFlags = parseSunStyleSectionFlags();
    442     } else {
    443       StringRef FlagsStr = getTok().getStringContents();
    444       Lex();
    445       extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
    446     }
    447 
    448     if (extraFlags == -1U)
    449       return TokError("unknown flag");
    450     Flags |= extraFlags;
    451 
    452     bool Mergeable = Flags & ELF::SHF_MERGE;
    453     bool Group = Flags & ELF::SHF_GROUP;
    454     if (Group && UseLastGroup)
    455       return TokError("Section cannot specifiy a group name while also acting "
    456                       "as a member of the last group");
    457 
    458     if (getLexer().isNot(AsmToken::Comma)) {
    459       if (Mergeable)
    460         return TokError("Mergeable section must specify the type");
    461       if (Group)
    462         return TokError("Group section must specify the type");
    463     } else {
    464       Lex();
    465       if (getLexer().is(AsmToken::At) || getLexer().is(AsmToken::Percent) ||
    466           getLexer().is(AsmToken::String)) {
    467         if (!getLexer().is(AsmToken::String))
    468           Lex();
    469       } else
    470         return TokError("expected '@<type>', '%<type>' or \"<type>\"");
    471 
    472       if (getParser().parseIdentifier(TypeName))
    473         return TokError("expected identifier in directive");
    474 
    475       if (Mergeable) {
    476         if (getLexer().isNot(AsmToken::Comma))
    477           return TokError("expected the entry size");
    478         Lex();
    479         if (getParser().parseAbsoluteExpression(Size))
    480           return true;
    481         if (Size <= 0)
    482           return TokError("entry size must be positive");
    483       }
    484 
    485       if (Group) {
    486         if (getLexer().isNot(AsmToken::Comma))
    487           return TokError("expected group name");
    488         Lex();
    489         if (getParser().parseIdentifier(GroupName))
    490           return true;
    491         if (getLexer().is(AsmToken::Comma)) {
    492           Lex();
    493           StringRef Linkage;
    494           if (getParser().parseIdentifier(Linkage))
    495             return true;
    496           if (Linkage != "comdat")
    497             return TokError("Linkage must be 'comdat'");
    498         }
    499       }
    500     }
    501   }
    502 
    503 EndStmt:
    504   if (getLexer().isNot(AsmToken::EndOfStatement))
    505     return TokError("unexpected token in directive");
    506 
    507   unsigned Type = ELF::SHT_PROGBITS;
    508 
    509   if (TypeName.empty()) {
    510     if (SectionName.startswith(".note"))
    511       Type = ELF::SHT_NOTE;
    512     else if (SectionName == ".init_array")
    513       Type = ELF::SHT_INIT_ARRAY;
    514     else if (SectionName == ".fini_array")
    515       Type = ELF::SHT_FINI_ARRAY;
    516     else if (SectionName == ".preinit_array")
    517       Type = ELF::SHT_PREINIT_ARRAY;
    518   } else {
    519     if (TypeName == "init_array")
    520       Type = ELF::SHT_INIT_ARRAY;
    521     else if (TypeName == "fini_array")
    522       Type = ELF::SHT_FINI_ARRAY;
    523     else if (TypeName == "preinit_array")
    524       Type = ELF::SHT_PREINIT_ARRAY;
    525     else if (TypeName == "nobits")
    526       Type = ELF::SHT_NOBITS;
    527     else if (TypeName == "progbits")
    528       Type = ELF::SHT_PROGBITS;
    529     else if (TypeName == "note")
    530       Type = ELF::SHT_NOTE;
    531     else if (TypeName == "unwind")
    532       Type = ELF::SHT_X86_64_UNWIND;
    533     else
    534       return TokError("unknown section type");
    535   }
    536 
    537   if (UseLastGroup) {
    538     MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
    539     if (const MCSectionELF *Section =
    540             cast_or_null<MCSectionELF>(CurrentSection.first))
    541       if (const MCSymbol *Group = Section->getGroup()) {
    542         GroupName = Group->getName();
    543         Flags |= ELF::SHF_GROUP;
    544       }
    545   }
    546 
    547   SectionKind Kind = computeSectionKind(Flags, Size);
    548   const MCSection *ELFSection = getContext().getELFSection(
    549       SectionName, Type, Flags, Kind, Size, GroupName);
    550   getStreamer().SwitchSection(ELFSection, Subsection);
    551 
    552   if (getContext().getGenDwarfForAssembly()) {
    553     auto &Sections = getContext().getGenDwarfSectionSyms();
    554     auto InsertResult = Sections.insert(
    555         std::make_pair(ELFSection, std::make_pair(nullptr, nullptr)));
    556     if (InsertResult.second) {
    557       if (getContext().getDwarfVersion() <= 2)
    558         Error(loc, "DWARF2 only supports one section per compilation unit");
    559 
    560       MCSymbol *SectionStartSymbol = getContext().CreateTempSymbol();
    561       getStreamer().EmitLabel(SectionStartSymbol);
    562       InsertResult.first->second.first = SectionStartSymbol;
    563     }
    564   }
    565 
    566   return false;
    567 }
    568 
    569 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
    570   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
    571   if (PreviousSection.first == nullptr)
    572       return TokError(".previous without corresponding .section");
    573   getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
    574 
    575   return false;
    576 }
    577 
    578 static MCSymbolAttr MCAttrForString(StringRef Type) {
    579   return StringSwitch<MCSymbolAttr>(Type)
    580           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
    581           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
    582           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
    583           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
    584           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
    585           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
    586                  MCSA_ELF_TypeIndFunction)
    587           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
    588           .Default(MCSA_Invalid);
    589 }
    590 
    591 /// ParseDirectiveELFType
    592 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
    593 ///  ::= .type identifier , #attribute
    594 ///  ::= .type identifier , @attribute
    595 ///  ::= .type identifier , %attribute
    596 ///  ::= .type identifier , "attribute"
    597 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
    598   StringRef Name;
    599   if (getParser().parseIdentifier(Name))
    600     return TokError("expected identifier in directive");
    601 
    602   // Handle the identifier as the key symbol.
    603   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
    604 
    605   // NOTE the comma is optional in all cases.  It is only documented as being
    606   // optional in the first case, however, GAS will silently treat the comma as
    607   // optional in all cases.  Furthermore, although the documentation states that
    608   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
    609   // accepts both the upper case name as well as the lower case aliases.
    610   if (getLexer().is(AsmToken::Comma))
    611     Lex();
    612 
    613   if (getLexer().isNot(AsmToken::Identifier) &&
    614       getLexer().isNot(AsmToken::Hash) && getLexer().isNot(AsmToken::At) &&
    615       getLexer().isNot(AsmToken::Percent) && getLexer().isNot(AsmToken::String))
    616     return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
    617                     "'%<type>' or \"<type>\"");
    618 
    619   if (getLexer().isNot(AsmToken::String) &&
    620       getLexer().isNot(AsmToken::Identifier))
    621     Lex();
    622 
    623   SMLoc TypeLoc = getLexer().getLoc();
    624 
    625   StringRef Type;
    626   if (getParser().parseIdentifier(Type))
    627     return TokError("expected symbol type in directive");
    628 
    629   MCSymbolAttr Attr = MCAttrForString(Type);
    630   if (Attr == MCSA_Invalid)
    631     return Error(TypeLoc, "unsupported attribute in '.type' directive");
    632 
    633   if (getLexer().isNot(AsmToken::EndOfStatement))
    634     return TokError("unexpected token in '.type' directive");
    635   Lex();
    636 
    637   getStreamer().EmitSymbolAttribute(Sym, Attr);
    638 
    639   return false;
    640 }
    641 
    642 /// ParseDirectiveIdent
    643 ///  ::= .ident string
    644 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
    645   if (getLexer().isNot(AsmToken::String))
    646     return TokError("unexpected token in '.ident' directive");
    647 
    648   StringRef Data = getTok().getIdentifier();
    649 
    650   Lex();
    651 
    652   getStreamer().EmitIdent(Data);
    653   return false;
    654 }
    655 
    656 /// ParseDirectiveSymver
    657 ///  ::= .symver foo, bar2@zed
    658 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
    659   StringRef Name;
    660   if (getParser().parseIdentifier(Name))
    661     return TokError("expected identifier in directive");
    662 
    663   if (getLexer().isNot(AsmToken::Comma))
    664     return TokError("expected a comma");
    665 
    666   // ARM assembly uses @ for a comment...
    667   // except when parsing the second parameter of the .symver directive.
    668   // Force the next symbol to allow @ in the identifier, which is
    669   // required for this directive and then reset it to its initial state.
    670   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
    671   getLexer().setAllowAtInIdentifier(true);
    672   Lex();
    673   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
    674 
    675   StringRef AliasName;
    676   if (getParser().parseIdentifier(AliasName))
    677     return TokError("expected identifier in directive");
    678 
    679   if (AliasName.find('@') == StringRef::npos)
    680     return TokError("expected a '@' in the name");
    681 
    682   MCSymbol *Alias = getContext().GetOrCreateSymbol(AliasName);
    683   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
    684   const MCExpr *Value = MCSymbolRefExpr::Create(Sym, getContext());
    685 
    686   getStreamer().EmitAssignment(Alias, Value);
    687   return false;
    688 }
    689 
    690 /// ParseDirectiveVersion
    691 ///  ::= .version string
    692 bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
    693   if (getLexer().isNot(AsmToken::String))
    694     return TokError("unexpected token in '.version' directive");
    695 
    696   StringRef Data = getTok().getIdentifier();
    697 
    698   Lex();
    699 
    700   const MCSection *Note =
    701     getContext().getELFSection(".note", ELF::SHT_NOTE, 0,
    702                                SectionKind::getReadOnly());
    703 
    704   getStreamer().PushSection();
    705   getStreamer().SwitchSection(Note);
    706   getStreamer().EmitIntValue(Data.size()+1, 4); // namesz.
    707   getStreamer().EmitIntValue(0, 4);             // descsz = 0 (no description).
    708   getStreamer().EmitIntValue(1, 4);             // type = NT_VERSION.
    709   getStreamer().EmitBytes(Data);                // name.
    710   getStreamer().EmitIntValue(0, 1);             // terminate the string.
    711   getStreamer().EmitValueToAlignment(4);        // ensure 4 byte alignment.
    712   getStreamer().PopSection();
    713   return false;
    714 }
    715 
    716 /// ParseDirectiveWeakref
    717 ///  ::= .weakref foo, bar
    718 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
    719   // FIXME: Share code with the other alias building directives.
    720 
    721   StringRef AliasName;
    722   if (getParser().parseIdentifier(AliasName))
    723     return TokError("expected identifier in directive");
    724 
    725   if (getLexer().isNot(AsmToken::Comma))
    726     return TokError("expected a comma");
    727 
    728   Lex();
    729 
    730   StringRef Name;
    731   if (getParser().parseIdentifier(Name))
    732     return TokError("expected identifier in directive");
    733 
    734   MCSymbol *Alias = getContext().GetOrCreateSymbol(AliasName);
    735 
    736   MCSymbol *Sym = getContext().GetOrCreateSymbol(Name);
    737 
    738   getStreamer().EmitWeakReference(Alias, Sym);
    739   return false;
    740 }
    741 
    742 bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
    743   const MCExpr *Subsection = nullptr;
    744   if (getLexer().isNot(AsmToken::EndOfStatement)) {
    745     if (getParser().parseExpression(Subsection))
    746      return true;
    747   }
    748 
    749   if (getLexer().isNot(AsmToken::EndOfStatement))
    750     return TokError("unexpected token in directive");
    751 
    752   getStreamer().SubSection(Subsection);
    753   return false;
    754 }
    755 
    756 namespace llvm {
    757 
    758 MCAsmParserExtension *createELFAsmParser() {
    759   return new ELFAsmParser;
    760 }
    761 
    762 }
    763