lib/MC/MCParser/ELFAsmParser.cpp

   1 //===- ELFAsmParser.cpp - ELF Assembly Parser -----------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/ADT/StringRef.h"
  10 #include "llvm/ADT/StringSwitch.h"
  11 #include "llvm/BinaryFormat/ELF.h"
  12 #include "llvm/MC/MCAsmInfo.h"
  13 #include "llvm/MC/MCContext.h"
  14 #include "llvm/MC/MCDirectives.h"
  15 #include "llvm/MC/MCExpr.h"
  16 #include "llvm/MC/MCParser/MCAsmLexer.h"
  17 #include "llvm/MC/MCParser/MCAsmParser.h"
  18 #include "llvm/MC/MCParser/MCAsmParserExtension.h"
  19 #include "llvm/MC/MCSection.h"
  20 #include "llvm/MC/MCSectionELF.h"
  21 #include "llvm/MC/MCStreamer.h"
  22 #include "llvm/MC/MCSymbol.h"
  23 #include "llvm/MC/MCSymbolELF.h"
  24 #include "llvm/MC/SectionKind.h"
  25 #include "llvm/Support/Casting.h"
  26 #include "llvm/Support/MathExtras.h"
  27 #include "llvm/Support/SMLoc.h"
  28 #include <cassert>
  29 #include <cstdint>
  30 #include <utility>
  31
  32 using namespace llvm;
  33
  34 namespace {
  35
  36 class ELFAsmParser : public MCAsmParserExtension {
  37   template<bool (ELFAsmParser::*HandlerMethod)(StringRef, SMLoc)>
  38   void addDirectiveHandler(StringRef Directive) {
  39     MCAsmParser::ExtensionDirectiveHandler Handler = std::make_pair(
  40         this, HandleDirective<ELFAsmParser, HandlerMethod>);
  41
  42     getParser().addDirectiveHandler(Directive, Handler);
  43   }
  44
  45   bool ParseSectionSwitch(StringRef Section, unsigned Type, unsigned Flags,
  46                           SectionKind Kind);
  47
  48 public:
  49   ELFAsmParser() { BracketExpressionsSupported = true; }
  50
  51   void Initialize(MCAsmParser &Parser) override {
  52     // Call the base implementation.
  53     this->MCAsmParserExtension::Initialize(Parser);
  54
  55     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveData>(".data");
  56     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveText>(".text");
  57     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveBSS>(".bss");
  58     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveRoData>(".rodata");
  59     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTData>(".tdata");
  60     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTBSS>(".tbss");
  61     addDirectiveHandler<
  62       &ELFAsmParser::ParseSectionDirectiveDataRel>(".data.rel");
  63     addDirectiveHandler<
  64       &ELFAsmParser::ParseSectionDirectiveDataRelRo>(".data.rel.ro");
  65     addDirectiveHandler<
  66       &ELFAsmParser::ParseSectionDirectiveEhFrame>(".eh_frame");
  67     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSection>(".section");
  68     addDirectiveHandler<
  69       &ELFAsmParser::ParseDirectivePushSection>(".pushsection");
  70     addDirectiveHandler<&ELFAsmParser::ParseDirectivePopSection>(".popsection");
  71     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSize>(".size");
  72     addDirectiveHandler<&ELFAsmParser::ParseDirectivePrevious>(".previous");
  73     addDirectiveHandler<&ELFAsmParser::ParseDirectiveType>(".type");
  74     addDirectiveHandler<&ELFAsmParser::ParseDirectiveIdent>(".ident");
  75     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymver>(".symver");
  76     addDirectiveHandler<&ELFAsmParser::ParseDirectiveVersion>(".version");
  77     addDirectiveHandler<&ELFAsmParser::ParseDirectiveWeakref>(".weakref");
  78     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".weak");
  79     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".local");
  80     addDirectiveHandler<
  81       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".protected");
  82     addDirectiveHandler<
  83       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".internal");
  84     addDirectiveHandler<
  85       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".hidden");
  86     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSubsection>(".subsection");
  87     addDirectiveHandler<&ELFAsmParser::ParseDirectiveCGProfile>(".cg_profile");
  88   }
  89
  90   // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
  91   // the best way for us to get access to it?
  92   bool ParseSectionDirectiveData(StringRef, SMLoc) {
  93     return ParseSectionSwitch(".data", ELF::SHT_PROGBITS,
  94                               ELF::SHF_WRITE | ELF::SHF_ALLOC,
  95                               SectionKind::getData());
  96   }
  97   bool ParseSectionDirectiveText(StringRef, SMLoc) {
  98     return ParseSectionSwitch(".text", ELF::SHT_PROGBITS,
  99                               ELF::SHF_EXECINSTR |
 100                               ELF::SHF_ALLOC, SectionKind::getText());
 101   }
 102   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
 103     return ParseSectionSwitch(".bss", ELF::SHT_NOBITS,
 104                               ELF::SHF_WRITE |
 105                               ELF::SHF_ALLOC, SectionKind::getBSS());
 106   }
 107   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
 108     return ParseSectionSwitch(".rodata", ELF::SHT_PROGBITS,
 109                               ELF::SHF_ALLOC,
 110                               SectionKind::getReadOnly());
 111   }
 112   bool ParseSectionDirectiveTData(StringRef, SMLoc) {
 113     return ParseSectionSwitch(".tdata", ELF::SHT_PROGBITS,
 114                               ELF::SHF_ALLOC |
 115                               ELF::SHF_TLS | ELF::SHF_WRITE,
 116                               SectionKind::getThreadData());
 117   }
 118   bool ParseSectionDirectiveTBSS(StringRef, SMLoc) {
 119     return ParseSectionSwitch(".tbss", ELF::SHT_NOBITS,
 120                               ELF::SHF_ALLOC |
 121                               ELF::SHF_TLS | ELF::SHF_WRITE,
 122                               SectionKind::getThreadBSS());
 123   }
 124   bool ParseSectionDirectiveDataRel(StringRef, SMLoc) {
 125     return ParseSectionSwitch(".data.rel", ELF::SHT_PROGBITS,
 126                               ELF::SHF_ALLOC | ELF::SHF_WRITE,
 127                               SectionKind::getData());
 128   }
 129   bool ParseSectionDirectiveDataRelRo(StringRef, SMLoc) {
 130     return ParseSectionSwitch(".data.rel.ro", ELF::SHT_PROGBITS,
 131                               ELF::SHF_ALLOC |
 132                               ELF::SHF_WRITE,
 133                               SectionKind::getReadOnlyWithRel());
 134   }
 135   bool ParseSectionDirectiveEhFrame(StringRef, SMLoc) {
 136     return ParseSectionSwitch(".eh_frame", ELF::SHT_PROGBITS,
 137                               ELF::SHF_ALLOC | ELF::SHF_WRITE,
 138                               SectionKind::getData());
 139   }
 140   bool ParseDirectivePushSection(StringRef, SMLoc);
 141   bool ParseDirectivePopSection(StringRef, SMLoc);
 142   bool ParseDirectiveSection(StringRef, SMLoc);
 143   bool ParseDirectiveSize(StringRef, SMLoc);
 144   bool ParseDirectivePrevious(StringRef, SMLoc);
 145   bool ParseDirectiveType(StringRef, SMLoc);
 146   bool ParseDirectiveIdent(StringRef, SMLoc);
 147   bool ParseDirectiveSymver(StringRef, SMLoc);
 148   bool ParseDirectiveVersion(StringRef, SMLoc);
 149   bool ParseDirectiveWeakref(StringRef, SMLoc);
 150   bool ParseDirectiveSymbolAttribute(StringRef, SMLoc);
 151   bool ParseDirectiveSubsection(StringRef, SMLoc);
 152   bool ParseDirectiveCGProfile(StringRef, SMLoc);
 153
 154 private:
 155   bool ParseSectionName(StringRef &SectionName);
 156   bool ParseSectionArguments(bool IsPush, SMLoc loc);
 157   unsigned parseSunStyleSectionFlags();
 158   bool maybeParseSectionType(StringRef &TypeName);
 159   bool parseMergeSize(int64_t &Size);
 160   bool parseGroup(StringRef &GroupName);
 161   bool parseMetadataSym(MCSymbolELF *&Associated);
 162   bool maybeParseUniqueID(int64_t &UniqueID);
 163 };
 164
 165 } // end anonymous namespace
 166
 167 /// ParseDirectiveSymbolAttribute
 168 ///  ::= { ".local", ".weak", ... } [ identifier ( , identifier )* ]
 169 bool ELFAsmParser::ParseDirectiveSymbolAttribute(StringRef Directive, SMLoc) {
 170   MCSymbolAttr Attr = StringSwitch<MCSymbolAttr>(Directive)
 171     .Case(".weak", MCSA_Weak)
 172     .Case(".local", MCSA_Local)
 173     .Case(".hidden", MCSA_Hidden)
 174     .Case(".internal", MCSA_Internal)
 175     .Case(".protected", MCSA_Protected)
 176     .Default(MCSA_Invalid);
 177   assert(Attr != MCSA_Invalid && "unexpected symbol attribute directive!");
 178   if (getLexer().isNot(AsmToken::EndOfStatement)) {
 179     while (true) {
 180       StringRef Name;
 181
 182       if (getParser().parseIdentifier(Name))
 183         return TokError("expected identifier in directive");
 184
 185       MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
 186
 187       getStreamer().EmitSymbolAttribute(Sym, Attr);
 188
 189       if (getLexer().is(AsmToken::EndOfStatement))
 190         break;
 191
 192       if (getLexer().isNot(AsmToken::Comma))
 193         return TokError("unexpected token in directive");
 194       Lex();
 195     }
 196   }
 197
 198   Lex();
 199   return false;
 200 }
 201
 202 bool ELFAsmParser::ParseSectionSwitch(StringRef Section, unsigned Type,
 203                                       unsigned Flags, SectionKind Kind) {
 204   const MCExpr *Subsection = nullptr;
 205   if (getLexer().isNot(AsmToken::EndOfStatement)) {
 206     if (getParser().parseExpression(Subsection))
 207       return true;
 208   }
 209   Lex();
 210
 211   getStreamer().SwitchSection(getContext().getELFSection(Section, Type, Flags),
 212                               Subsection);
 213
 214   return false;
 215 }
 216
 217 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
 218   StringRef Name;
 219   if (getParser().parseIdentifier(Name))
 220     return TokError("expected identifier in directive");
 221   MCSymbolELF *Sym = cast<MCSymbolELF>(getContext().getOrCreateSymbol(Name));
 222
 223   if (getLexer().isNot(AsmToken::Comma))
 224     return TokError("unexpected token in directive");
 225   Lex();
 226
 227   const MCExpr *Expr;
 228   if (getParser().parseExpression(Expr))
 229     return true;
 230
 231   if (getLexer().isNot(AsmToken::EndOfStatement))
 232     return TokError("unexpected token in directive");
 233   Lex();
 234
 235   getStreamer().emitELFSize(Sym, Expr);
 236   return false;
 237 }
 238
 239 bool ELFAsmParser::ParseSectionName(StringRef &SectionName) {
 240   // A section name can contain -, so we cannot just use
 241   // parseIdentifier.
 242   SMLoc FirstLoc = getLexer().getLoc();
 243   unsigned Size = 0;
 244
 245   if (getLexer().is(AsmToken::String)) {
 246     SectionName = getTok().getIdentifier();
 247     Lex();
 248     return false;
 249   }
 250
 251   while (!getParser().hasPendingError()) {
 252     SMLoc PrevLoc = getLexer().getLoc();
 253     if (getLexer().is(AsmToken::Comma) ||
 254       getLexer().is(AsmToken::EndOfStatement))
 255       break;
 256
 257     unsigned CurSize;
 258     if (getLexer().is(AsmToken::String)) {
 259       CurSize = getTok().getIdentifier().size() + 2;
 260       Lex();
 261     } else if (getLexer().is(AsmToken::Identifier)) {
 262       CurSize = getTok().getIdentifier().size();
 263       Lex();
 264     } else {
 265       CurSize = getTok().getString().size();
 266       Lex();
 267     }
 268     Size += CurSize;
 269     SectionName = StringRef(FirstLoc.getPointer(), Size);
 270
 271     // Make sure the following token is adjacent.
 272     if (PrevLoc.getPointer() + CurSize != getTok().getLoc().getPointer())
 273       break;
 274   }
 275   if (Size == 0)
 276     return true;
 277
 278   return false;
 279 }
 280
 281 static unsigned parseSectionFlags(StringRef flagsStr, bool *UseLastGroup) {
 282   unsigned flags = 0;
 283
 284   // If a valid numerical value is set for the section flag, use it verbatim
 285   if (!flagsStr.getAsInteger(0, flags))
 286     return flags;
 287
 288   for (char i : flagsStr) {
 289     switch (i) {
 290     case 'a':
 291       flags |= ELF::SHF_ALLOC;
 292       break;
 293     case 'e':
 294       flags |= ELF::SHF_EXCLUDE;
 295       break;
 296     case 'x':
 297       flags |= ELF::SHF_EXECINSTR;
 298       break;
 299     case 'w':
 300       flags |= ELF::SHF_WRITE;
 301       break;
 302     case 'o':
 303       flags |= ELF::SHF_LINK_ORDER;
 304       break;
 305     case 'M':
 306       flags |= ELF::SHF_MERGE;
 307       break;
 308     case 'S':
 309       flags |= ELF::SHF_STRINGS;
 310       break;
 311     case 'T':
 312       flags |= ELF::SHF_TLS;
 313       break;
 314     case 'c':
 315       flags |= ELF::XCORE_SHF_CP_SECTION;
 316       break;
 317     case 'd':
 318       flags |= ELF::XCORE_SHF_DP_SECTION;
 319       break;
 320     case 'y':
 321       flags |= ELF::SHF_ARM_PURECODE;
 322       break;
 323     case 's':
 324       flags |= ELF::SHF_HEX_GPREL;
 325       break;
 326     case 'G':
 327       flags |= ELF::SHF_GROUP;
 328       break;
 329     case '?':
 330       *UseLastGroup = true;
 331       break;
 332     default:
 333       return -1U;
 334     }
 335   }
 336
 337   return flags;
 338 }
 339
 340 unsigned ELFAsmParser::parseSunStyleSectionFlags() {
 341   unsigned flags = 0;
 342   while (getLexer().is(AsmToken::Hash)) {
 343     Lex(); // Eat the #.
 344
 345     if (!getLexer().is(AsmToken::Identifier))
 346       return -1U;
 347
 348     StringRef flagId = getTok().getIdentifier();
 349     if (flagId == "alloc")
 350       flags |= ELF::SHF_ALLOC;
 351     else if (flagId == "execinstr")
 352       flags |= ELF::SHF_EXECINSTR;
 353     else if (flagId == "write")
 354       flags |= ELF::SHF_WRITE;
 355     else if (flagId == "tls")
 356       flags |= ELF::SHF_TLS;
 357     else
 358       return -1U;
 359
 360     Lex(); // Eat the flag.
 361
 362     if (!getLexer().is(AsmToken::Comma))
 363         break;
 364     Lex(); // Eat the comma.
 365   }
 366   return flags;
 367 }
 368
 369
 370 bool ELFAsmParser::ParseDirectivePushSection(StringRef s, SMLoc loc) {
 371   getStreamer().PushSection();
 372
 373   if (ParseSectionArguments(/*IsPush=*/true, loc)) {
 374     getStreamer().PopSection();
 375     return true;
 376   }
 377
 378   return false;
 379 }
 380
 381 bool ELFAsmParser::ParseDirectivePopSection(StringRef, SMLoc) {
 382   if (!getStreamer().PopSection())
 383     return TokError(".popsection without corresponding .pushsection");
 384   return false;
 385 }
 386
 387 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc loc) {
 388   return ParseSectionArguments(/*IsPush=*/false, loc);
 389 }
 390
 391 bool ELFAsmParser::maybeParseSectionType(StringRef &TypeName) {
 392   MCAsmLexer &L = getLexer();
 393   if (L.isNot(AsmToken::Comma))
 394     return false;
 395   Lex();
 396   if (L.isNot(AsmToken::At) && L.isNot(AsmToken::Percent) &&
 397       L.isNot(AsmToken::String)) {
 398     if (L.getAllowAtInIdentifier())
 399       return TokError("expected '@<type>', '%<type>' or \"<type>\"");
 400     else
 401       return TokError("expected '%<type>' or \"<type>\"");
 402   }
 403   if (!L.is(AsmToken::String))
 404     Lex();
 405   if (L.is(AsmToken::Integer)) {
 406     TypeName = getTok().getString();
 407     Lex();
 408   } else if (getParser().parseIdentifier(TypeName))
 409     return TokError("expected identifier in directive");
 410   return false;
 411 }
 412
 413 bool ELFAsmParser::parseMergeSize(int64_t &Size) {
 414   if (getLexer().isNot(AsmToken::Comma))
 415     return TokError("expected the entry size");
 416   Lex();
 417   if (getParser().parseAbsoluteExpression(Size))
 418     return true;
 419   if (Size <= 0)
 420     return TokError("entry size must be positive");
 421   return false;
 422 }
 423
 424 bool ELFAsmParser::parseGroup(StringRef &GroupName) {
 425   MCAsmLexer &L = getLexer();
 426   if (L.isNot(AsmToken::Comma))
 427     return TokError("expected group name");
 428   Lex();
 429   if (L.is(AsmToken::Integer)) {
 430     GroupName = getTok().getString();
 431     Lex();
 432   } else if (getParser().parseIdentifier(GroupName)) {
 433     return TokError("invalid group name");
 434   }
 435   if (L.is(AsmToken::Comma)) {
 436     Lex();
 437     StringRef Linkage;
 438     if (getParser().parseIdentifier(Linkage))
 439       return TokError("invalid linkage");
 440     if (Linkage != "comdat")
 441       return TokError("Linkage must be 'comdat'");
 442   }
 443   return false;
 444 }
 445
 446 bool ELFAsmParser::parseMetadataSym(MCSymbolELF *&Associated) {
 447   MCAsmLexer &L = getLexer();
 448   if (L.isNot(AsmToken::Comma))
 449     return TokError("expected metadata symbol");
 450   Lex();
 451   StringRef Name;
 452   if (getParser().parseIdentifier(Name))
 453     return TokError("invalid metadata symbol");
 454   Associated = dyn_cast_or_null<MCSymbolELF>(getContext().lookupSymbol(Name));
 455   if (!Associated || !Associated->isInSection())
 456     return TokError("symbol is not in a section: " + Name);
 457   return false;
 458 }
 459
 460 bool ELFAsmParser::maybeParseUniqueID(int64_t &UniqueID) {
 461   MCAsmLexer &L = getLexer();
 462   if (L.isNot(AsmToken::Comma))
 463     return false;
 464   Lex();
 465   StringRef UniqueStr;
 466   if (getParser().parseIdentifier(UniqueStr))
 467     return TokError("expected identifier in directive");
 468   if (UniqueStr != "unique")
 469     return TokError("expected 'unique'");
 470   if (L.isNot(AsmToken::Comma))
 471     return TokError("expected commma");
 472   Lex();
 473   if (getParser().parseAbsoluteExpression(UniqueID))
 474     return true;
 475   if (UniqueID < 0)
 476     return TokError("unique id must be positive");
 477   if (!isUInt<32>(UniqueID) || UniqueID == ~0U)
 478     return TokError("unique id is too large");
 479   return false;
 480 }
 481
 482 static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
 483   return SectionName.startswith(Prefix) || SectionName == Prefix.drop_back();
 484 }
 485
 486 bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
 487   StringRef SectionName;
 488
 489   if (ParseSectionName(SectionName))
 490     return TokError("expected identifier in directive");
 491
 492   StringRef TypeName;
 493   int64_t Size = 0;
 494   StringRef GroupName;
 495   unsigned Flags = 0;
 496   const MCExpr *Subsection = nullptr;
 497   bool UseLastGroup = false;
 498   MCSymbolELF *Associated = nullptr;
 499   int64_t UniqueID = ~0;
 500
 501   // Set the defaults first.
 502   if (hasPrefix(SectionName, ".rodata.") || SectionName == ".rodata1")
 503     Flags |= ELF::SHF_ALLOC;
 504   else if (SectionName == ".fini" || SectionName == ".init" ||
 505            hasPrefix(SectionName, ".text."))
 506     Flags |= ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
 507   else if (hasPrefix(SectionName, ".data.") || SectionName == ".data1" ||
 508            hasPrefix(SectionName, ".bss.") ||
 509            hasPrefix(SectionName, ".init_array.") ||
 510            hasPrefix(SectionName, ".fini_array.") ||
 511            hasPrefix(SectionName, ".preinit_array."))
 512     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE;
 513   else if (hasPrefix(SectionName, ".tdata.") ||
 514            hasPrefix(SectionName, ".tbss."))
 515     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_TLS;
 516
 517   if (getLexer().is(AsmToken::Comma)) {
 518     Lex();
 519
 520     if (IsPush && getLexer().isNot(AsmToken::String)) {
 521       if (getParser().parseExpression(Subsection))
 522         return true;
 523       if (getLexer().isNot(AsmToken::Comma))
 524         goto EndStmt;
 525       Lex();
 526     }
 527
 528     unsigned extraFlags;
 529
 530     if (getLexer().isNot(AsmToken::String)) {
 531       if (!getContext().getAsmInfo()->usesSunStyleELFSectionSwitchSyntax()
 532           || getLexer().isNot(AsmToken::Hash))
 533         return TokError("expected string in directive");
 534       extraFlags = parseSunStyleSectionFlags();
 535     } else {
 536       StringRef FlagsStr = getTok().getStringContents();
 537       Lex();
 538       extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
 539     }
 540
 541     if (extraFlags == -1U)
 542       return TokError("unknown flag");
 543     Flags |= extraFlags;
 544
 545     bool Mergeable = Flags & ELF::SHF_MERGE;
 546     bool Group = Flags & ELF::SHF_GROUP;
 547     if (Group && UseLastGroup)
 548       return TokError("Section cannot specifiy a group name while also acting "
 549                       "as a member of the last group");
 550
 551     if (maybeParseSectionType(TypeName))
 552       return true;
 553
 554     MCAsmLexer &L = getLexer();
 555     if (TypeName.empty()) {
 556       if (Mergeable)
 557         return TokError("Mergeable section must specify the type");
 558       if (Group)
 559         return TokError("Group section must specify the type");
 560       if (L.isNot(AsmToken::EndOfStatement))
 561         return TokError("unexpected token in directive");
 562     }
 563
 564     if (Mergeable)
 565       if (parseMergeSize(Size))
 566         return true;
 567     if (Group)
 568       if (parseGroup(GroupName))
 569         return true;
 570     if (Flags & ELF::SHF_LINK_ORDER)
 571       if (parseMetadataSym(Associated))
 572         return true;
 573     if (maybeParseUniqueID(UniqueID))
 574       return true;
 575   }
 576
 577 EndStmt:
 578   if (getLexer().isNot(AsmToken::EndOfStatement))
 579     return TokError("unexpected token in directive");
 580   Lex();
 581
 582   unsigned Type = ELF::SHT_PROGBITS;
 583
 584   if (TypeName.empty()) {
 585     if (SectionName.startswith(".note"))
 586       Type = ELF::SHT_NOTE;
 587     else if (hasPrefix(SectionName, ".init_array."))
 588       Type = ELF::SHT_INIT_ARRAY;
 589     else if (hasPrefix(SectionName, ".bss."))
 590       Type = ELF::SHT_NOBITS;
 591     else if (hasPrefix(SectionName, ".tbss."))
 592       Type = ELF::SHT_NOBITS;
 593     else if (hasPrefix(SectionName, ".fini_array."))
 594       Type = ELF::SHT_FINI_ARRAY;
 595     else if (hasPrefix(SectionName, ".preinit_array."))
 596       Type = ELF::SHT_PREINIT_ARRAY;
 597   } else {
 598     if (TypeName == "init_array")
 599       Type = ELF::SHT_INIT_ARRAY;
 600     else if (TypeName == "fini_array")
 601       Type = ELF::SHT_FINI_ARRAY;
 602     else if (TypeName == "preinit_array")
 603       Type = ELF::SHT_PREINIT_ARRAY;
 604     else if (TypeName == "nobits")
 605       Type = ELF::SHT_NOBITS;
 606     else if (TypeName == "progbits")
 607       Type = ELF::SHT_PROGBITS;
 608     else if (TypeName == "note")
 609       Type = ELF::SHT_NOTE;
 610     else if (TypeName == "unwind")
 611       Type = ELF::SHT_X86_64_UNWIND;
 612     else if (TypeName == "llvm_odrtab")
 613       Type = ELF::SHT_LLVM_ODRTAB;
 614     else if (TypeName == "llvm_linker_options")
 615       Type = ELF::SHT_LLVM_LINKER_OPTIONS;
 616     else if (TypeName == "llvm_call_graph_profile")
 617       Type = ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
 618     else if (TypeName == "llvm_dependent_libraries")
 619       Type = ELF::SHT_LLVM_DEPENDENT_LIBRARIES;
 620     else if (TypeName == "llvm_sympart")
 621       Type = ELF::SHT_LLVM_SYMPART;
 622     else if (TypeName.getAsInteger(0, Type))
 623       return TokError("unknown section type");
 624   }
 625
 626   if (UseLastGroup) {
 627     MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
 628     if (const MCSectionELF *Section =
 629             cast_or_null<MCSectionELF>(CurrentSection.first))
 630       if (const MCSymbol *Group = Section->getGroup()) {
 631         GroupName = Group->getName();
 632         Flags |= ELF::SHF_GROUP;
 633       }
 634   }
 635
 636   MCSection *ELFSection =
 637       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
 638                                  UniqueID, Associated);
 639   getStreamer().SwitchSection(ELFSection, Subsection);
 640
 641   if (getContext().getGenDwarfForAssembly()) {
 642     bool InsertResult = getContext().addGenDwarfSection(ELFSection);
 643     if (InsertResult) {
 644       if (getContext().getDwarfVersion() <= 2)
 645         Warning(loc, "DWARF2 only supports one section per compilation unit");
 646
 647       if (!ELFSection->getBeginSymbol()) {
 648         MCSymbol *SectionStartSymbol = getContext().createTempSymbol();
 649         getStreamer().EmitLabel(SectionStartSymbol);
 650         ELFSection->setBeginSymbol(SectionStartSymbol);
 651       }
 652     }
 653   }
 654
 655   return false;
 656 }
 657
 658 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
 659   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
 660   if (PreviousSection.first == nullptr)
 661       return TokError(".previous without corresponding .section");
 662   getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
 663
 664   return false;
 665 }
 666
 667 static MCSymbolAttr MCAttrForString(StringRef Type) {
 668   return StringSwitch<MCSymbolAttr>(Type)
 669           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
 670           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
 671           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
 672           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
 673           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
 674           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
 675                  MCSA_ELF_TypeIndFunction)
 676           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
 677           .Default(MCSA_Invalid);
 678 }
 679
 680 /// ParseDirectiveELFType
 681 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
 682 ///  ::= .type identifier , #attribute
 683 ///  ::= .type identifier , @attribute
 684 ///  ::= .type identifier , %attribute
 685 ///  ::= .type identifier , "attribute"
 686 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
 687   StringRef Name;
 688   if (getParser().parseIdentifier(Name))
 689     return TokError("expected identifier in directive");
 690
 691   // Handle the identifier as the key symbol.
 692   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
 693
 694   // NOTE the comma is optional in all cases.  It is only documented as being
 695   // optional in the first case, however, GAS will silently treat the comma as
 696   // optional in all cases.  Furthermore, although the documentation states that
 697   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
 698   // accepts both the upper case name as well as the lower case aliases.
 699   if (getLexer().is(AsmToken::Comma))
 700     Lex();
 701
 702   if (getLexer().isNot(AsmToken::Identifier) &&
 703       getLexer().isNot(AsmToken::Hash) &&
 704       getLexer().isNot(AsmToken::Percent) &&
 705       getLexer().isNot(AsmToken::String)) {
 706     if (!getLexer().getAllowAtInIdentifier())
 707       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
 708                       "'%<type>' or \"<type>\"");
 709     else if (getLexer().isNot(AsmToken::At))
 710       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
 711                       "'%<type>' or \"<type>\"");
 712   }
 713
 714   if (getLexer().isNot(AsmToken::String) &&
 715       getLexer().isNot(AsmToken::Identifier))
 716     Lex();
 717
 718   SMLoc TypeLoc = getLexer().getLoc();
 719
 720   StringRef Type;
 721   if (getParser().parseIdentifier(Type))
 722     return TokError("expected symbol type in directive");
 723
 724   MCSymbolAttr Attr = MCAttrForString(Type);
 725   if (Attr == MCSA_Invalid)
 726     return Error(TypeLoc, "unsupported attribute in '.type' directive");
 727
 728   if (getLexer().isNot(AsmToken::EndOfStatement))
 729     return TokError("unexpected token in '.type' directive");
 730   Lex();
 731
 732   getStreamer().EmitSymbolAttribute(Sym, Attr);
 733
 734   return false;
 735 }
 736
 737 /// ParseDirectiveIdent
 738 ///  ::= .ident string
 739 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
 740   if (getLexer().isNot(AsmToken::String))
 741     return TokError("unexpected token in '.ident' directive");
 742
 743   StringRef Data = getTok().getIdentifier();
 744
 745   Lex();
 746
 747   if (getLexer().isNot(AsmToken::EndOfStatement))
 748     return TokError("unexpected token in '.ident' directive");
 749   Lex();
 750
 751   getStreamer().EmitIdent(Data);
 752   return false;
 753 }
 754
 755 /// ParseDirectiveSymver
 756 ///  ::= .symver foo, bar2@zed
 757 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
 758   StringRef Name;
 759   if (getParser().parseIdentifier(Name))
 760     return TokError("expected identifier in directive");
 761
 762   if (getLexer().isNot(AsmToken::Comma))
 763     return TokError("expected a comma");
 764
 765   // ARM assembly uses @ for a comment...
 766   // except when parsing the second parameter of the .symver directive.
 767   // Force the next symbol to allow @ in the identifier, which is
 768   // required for this directive and then reset it to its initial state.
 769   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
 770   getLexer().setAllowAtInIdentifier(true);
 771   Lex();
 772   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
 773
 774   StringRef AliasName;
 775   if (getParser().parseIdentifier(AliasName))
 776     return TokError("expected identifier in directive");
 777
 778   if (AliasName.find('@') == StringRef::npos)
 779     return TokError("expected a '@' in the name");
 780
 781   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
 782   getStreamer().emitELFSymverDirective(AliasName, Sym);
 783   return false;
 784 }
 785
 786 /// ParseDirectiveVersion
 787 ///  ::= .version string
 788 bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
 789   if (getLexer().isNot(AsmToken::String))
 790     return TokError("unexpected token in '.version' directive");
 791
 792   StringRef Data = getTok().getIdentifier();
 793
 794   Lex();
 795
 796   MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
 797
 798   getStreamer().PushSection();
 799   getStreamer().SwitchSection(Note);
 800   getStreamer().EmitIntValue(Data.size()+1, 4); // namesz.
 801   getStreamer().EmitIntValue(0, 4);             // descsz = 0 (no description).
 802   getStreamer().EmitIntValue(1, 4);             // type = NT_VERSION.
 803   getStreamer().EmitBytes(Data);                // name.
 804   getStreamer().EmitIntValue(0, 1);             // terminate the string.
 805   getStreamer().EmitValueToAlignment(4);        // ensure 4 byte alignment.
 806   getStreamer().PopSection();
 807   return false;
 808 }
 809
 810 /// ParseDirectiveWeakref
 811 ///  ::= .weakref foo, bar
 812 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
 813   // FIXME: Share code with the other alias building directives.
 814
 815   StringRef AliasName;
 816   if (getParser().parseIdentifier(AliasName))
 817     return TokError("expected identifier in directive");
 818
 819   if (getLexer().isNot(AsmToken::Comma))
 820     return TokError("expected a comma");
 821
 822   Lex();
 823
 824   StringRef Name;
 825   if (getParser().parseIdentifier(Name))
 826     return TokError("expected identifier in directive");
 827
 828   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
 829
 830   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
 831
 832   getStreamer().EmitWeakReference(Alias, Sym);
 833   return false;
 834 }
 835
 836 bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
 837   const MCExpr *Subsection = nullptr;
 838   if (getLexer().isNot(AsmToken::EndOfStatement)) {
 839     if (getParser().parseExpression(Subsection))
 840      return true;
 841   }
 842
 843   if (getLexer().isNot(AsmToken::EndOfStatement))
 844     return TokError("unexpected token in directive");
 845
 846   Lex();
 847
 848   getStreamer().SubSection(Subsection);
 849   return false;
 850 }
 851
 852 /// ParseDirectiveCGProfile
 853 ///  ::= .cg_profile identifier, identifier, <number>
 854 bool ELFAsmParser::ParseDirectiveCGProfile(StringRef, SMLoc) {
 855   StringRef From;
 856   SMLoc FromLoc = getLexer().getLoc();
 857   if (getParser().parseIdentifier(From))
 858     return TokError("expected identifier in directive");
 859
 860   if (getLexer().isNot(AsmToken::Comma))
 861     return TokError("expected a comma");
 862   Lex();
 863
 864   StringRef To;
 865   SMLoc ToLoc = getLexer().getLoc();
 866   if (getParser().parseIdentifier(To))
 867     return TokError("expected identifier in directive");
 868
 869   if (getLexer().isNot(AsmToken::Comma))
 870     return TokError("expected a comma");
 871   Lex();
 872
 873   int64_t Count;
 874   if (getParser().parseIntToken(
 875           Count, "expected integer count in '.cg_profile' directive"))
 876     return true;
 877
 878   if (getLexer().isNot(AsmToken::EndOfStatement))
 879     return TokError("unexpected token in directive");
 880
 881   MCSymbol *FromSym = getContext().getOrCreateSymbol(From);
 882   MCSymbol *ToSym = getContext().getOrCreateSymbol(To);
 883
 884   getStreamer().emitCGProfileEntry(
 885       MCSymbolRefExpr::create(FromSym, MCSymbolRefExpr::VK_None, getContext(),
 886                               FromLoc),
 887       MCSymbolRefExpr::create(ToSym, MCSymbolRefExpr::VK_None, getContext(),
 888                               ToLoc),
 889       Count);
 890   return false;
 891 }
 892
 893 namespace llvm {
 894
 895 MCAsmParserExtension *createELFAsmParser() {
 896   return new ELFAsmParser;
 897 }
 898
 899 } // end namespace llvm