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
32using namespace llvm;
33
34namespace {
35
36class 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
48public:
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
154private:
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 parseLinkedToSym(MCSymbolELF *&LinkedToSym);
162  bool maybeParseUniqueID(int64_t &UniqueID);
163};
164
165} // end anonymous namespace
166
167/// ParseDirectiveSymbolAttribute
168///  ::= { ".local", ".weak", ... } [ identifier ( , identifier )* ]
169bool 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
202bool 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
217bool 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
239bool 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
281static 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
340unsigned 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
370bool 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
381bool ELFAsmParser::ParseDirectivePopSection(StringRef, SMLoc) {
382  if (!getStreamer().PopSection())
383    return TokError(".popsection without corresponding .pushsection");
384  return false;
385}
386
387bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc loc) {
388  return ParseSectionArguments(/*IsPush=*/false, loc);
389}
390
391bool 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
413bool 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
424bool 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
446bool ELFAsmParser::parseLinkedToSym(MCSymbolELF *&LinkedToSym) {
447  MCAsmLexer &L = getLexer();
448  if (L.isNot(AsmToken::Comma))
449    return TokError("expected linked-to symbol");
450  Lex();
451  StringRef Name;
452  SMLoc StartLoc = L.getLoc();
453  if (getParser().parseIdentifier(Name))
454    return TokError("invalid linked-to symbol");
455  LinkedToSym = dyn_cast_or_null<MCSymbolELF>(getContext().lookupSymbol(Name));
456  if (!LinkedToSym || !LinkedToSym->isInSection())
457    return Error(StartLoc, "linked-to symbol is not in a section: " + Name);
458  return false;
459}
460
461bool ELFAsmParser::maybeParseUniqueID(int64_t &UniqueID) {
462  MCAsmLexer &L = getLexer();
463  if (L.isNot(AsmToken::Comma))
464    return false;
465  Lex();
466  StringRef UniqueStr;
467  if (getParser().parseIdentifier(UniqueStr))
468    return TokError("expected identifier in directive");
469  if (UniqueStr != "unique")
470    return TokError("expected 'unique'");
471  if (L.isNot(AsmToken::Comma))
472    return TokError("expected commma");
473  Lex();
474  if (getParser().parseAbsoluteExpression(UniqueID))
475    return true;
476  if (UniqueID < 0)
477    return TokError("unique id must be positive");
478  if (!isUInt<32>(UniqueID) || UniqueID == ~0U)
479    return TokError("unique id is too large");
480  return false;
481}
482
483static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
484  return SectionName.startswith(Prefix) || SectionName == Prefix.drop_back();
485}
486
487bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
488  StringRef SectionName;
489
490  if (ParseSectionName(SectionName))
491    return TokError("expected identifier in directive");
492
493  StringRef TypeName;
494  int64_t Size = 0;
495  StringRef GroupName;
496  unsigned Flags = 0;
497  const MCExpr *Subsection = nullptr;
498  bool UseLastGroup = false;
499  MCSymbolELF *LinkedToSym = nullptr;
500  int64_t UniqueID = ~0;
501
502  // Set the defaults first.
503  if (hasPrefix(SectionName, ".rodata.") || SectionName == ".rodata1")
504    Flags |= ELF::SHF_ALLOC;
505  else if (SectionName == ".fini" || SectionName == ".init" ||
506           hasPrefix(SectionName, ".text."))
507    Flags |= ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
508  else if (hasPrefix(SectionName, ".data.") || SectionName == ".data1" ||
509           hasPrefix(SectionName, ".bss.") ||
510           hasPrefix(SectionName, ".init_array.") ||
511           hasPrefix(SectionName, ".fini_array.") ||
512           hasPrefix(SectionName, ".preinit_array."))
513    Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE;
514  else if (hasPrefix(SectionName, ".tdata.") ||
515           hasPrefix(SectionName, ".tbss."))
516    Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_TLS;
517
518  if (getLexer().is(AsmToken::Comma)) {
519    Lex();
520
521    if (IsPush && getLexer().isNot(AsmToken::String)) {
522      if (getParser().parseExpression(Subsection))
523        return true;
524      if (getLexer().isNot(AsmToken::Comma))
525        goto EndStmt;
526      Lex();
527    }
528
529    unsigned extraFlags;
530
531    if (getLexer().isNot(AsmToken::String)) {
532      if (!getContext().getAsmInfo()->usesSunStyleELFSectionSwitchSyntax()
533          || getLexer().isNot(AsmToken::Hash))
534        return TokError("expected string in directive");
535      extraFlags = parseSunStyleSectionFlags();
536    } else {
537      StringRef FlagsStr = getTok().getStringContents();
538      Lex();
539      extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
540    }
541
542    if (extraFlags == -1U)
543      return TokError("unknown flag");
544    Flags |= extraFlags;
545
546    bool Mergeable = Flags & ELF::SHF_MERGE;
547    bool Group = Flags & ELF::SHF_GROUP;
548    if (Group && UseLastGroup)
549      return TokError("Section cannot specifiy a group name while also acting "
550                      "as a member of the last group");
551
552    if (maybeParseSectionType(TypeName))
553      return true;
554
555    MCAsmLexer &L = getLexer();
556    if (TypeName.empty()) {
557      if (Mergeable)
558        return TokError("Mergeable section must specify the type");
559      if (Group)
560        return TokError("Group section must specify the type");
561      if (L.isNot(AsmToken::EndOfStatement))
562        return TokError("unexpected token in directive");
563    }
564
565    if (Mergeable)
566      if (parseMergeSize(Size))
567        return true;
568    if (Group)
569      if (parseGroup(GroupName))
570        return true;
571    if (Flags & ELF::SHF_LINK_ORDER)
572      if (parseLinkedToSym(LinkedToSym))
573        return true;
574    if (maybeParseUniqueID(UniqueID))
575      return true;
576  }
577
578EndStmt:
579  if (getLexer().isNot(AsmToken::EndOfStatement))
580    return TokError("unexpected token in directive");
581  Lex();
582
583  unsigned Type = ELF::SHT_PROGBITS;
584
585  if (TypeName.empty()) {
586    if (SectionName.startswith(".note"))
587      Type = ELF::SHT_NOTE;
588    else if (hasPrefix(SectionName, ".init_array."))
589      Type = ELF::SHT_INIT_ARRAY;
590    else if (hasPrefix(SectionName, ".bss."))
591      Type = ELF::SHT_NOBITS;
592    else if (hasPrefix(SectionName, ".tbss."))
593      Type = ELF::SHT_NOBITS;
594    else if (hasPrefix(SectionName, ".fini_array."))
595      Type = ELF::SHT_FINI_ARRAY;
596    else if (hasPrefix(SectionName, ".preinit_array."))
597      Type = ELF::SHT_PREINIT_ARRAY;
598  } else {
599    if (TypeName == "init_array")
600      Type = ELF::SHT_INIT_ARRAY;
601    else if (TypeName == "fini_array")
602      Type = ELF::SHT_FINI_ARRAY;
603    else if (TypeName == "preinit_array")
604      Type = ELF::SHT_PREINIT_ARRAY;
605    else if (TypeName == "nobits")
606      Type = ELF::SHT_NOBITS;
607    else if (TypeName == "progbits")
608      Type = ELF::SHT_PROGBITS;
609    else if (TypeName == "note")
610      Type = ELF::SHT_NOTE;
611    else if (TypeName == "unwind")
612      Type = ELF::SHT_X86_64_UNWIND;
613    else if (TypeName == "llvm_odrtab")
614      Type = ELF::SHT_LLVM_ODRTAB;
615    else if (TypeName == "llvm_linker_options")
616      Type = ELF::SHT_LLVM_LINKER_OPTIONS;
617    else if (TypeName == "llvm_call_graph_profile")
618      Type = ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
619    else if (TypeName == "llvm_dependent_libraries")
620      Type = ELF::SHT_LLVM_DEPENDENT_LIBRARIES;
621    else if (TypeName == "llvm_sympart")
622      Type = ELF::SHT_LLVM_SYMPART;
623    else if (TypeName.getAsInteger(0, Type))
624      return TokError("unknown section type");
625  }
626
627  if (UseLastGroup) {
628    MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
629    if (const MCSectionELF *Section =
630            cast_or_null<MCSectionELF>(CurrentSection.first))
631      if (const MCSymbol *Group = Section->getGroup()) {
632        GroupName = Group->getName();
633        Flags |= ELF::SHF_GROUP;
634      }
635  }
636
637  MCSectionELF *Section = getContext().getELFSection(
638      SectionName, Type, Flags, Size, GroupName, UniqueID, LinkedToSym);
639  getStreamer().SwitchSection(Section, Subsection);
640  // x86-64 psABI names SHT_X86_64_UNWIND as the canonical type for .eh_frame,
641  // but GNU as emits SHT_PROGBITS .eh_frame for .cfi_* directives. Don't error
642  // for SHT_PROGBITS .eh_frame
643  if (Section->getType() != Type &&
644      !(SectionName == ".eh_frame" && Type == ELF::SHT_PROGBITS))
645    Error(loc, "changed section type for " + SectionName + ", expected: 0x" +
646                   utohexstr(Section->getType()));
647  // Check that flags are used consistently. However, the GNU assembler permits
648  // to leave out in subsequent uses of the same sections; for compatibility,
649  // do likewise.
650  if ((Flags || Size || !TypeName.empty()) && Section->getFlags() != Flags)
651    Error(loc, "changed section flags for " + SectionName + ", expected: 0x" +
652                   utohexstr(Section->getFlags()));
653  if ((Flags || Size || !TypeName.empty()) && Section->getEntrySize() != Size)
654    Error(loc, "changed section entsize for " + SectionName +
655                   ", expected: " + Twine(Section->getEntrySize()));
656
657  if (getContext().getGenDwarfForAssembly()) {
658    bool InsertResult = getContext().addGenDwarfSection(Section);
659    if (InsertResult) {
660      if (getContext().getDwarfVersion() <= 2)
661        Warning(loc, "DWARF2 only supports one section per compilation unit");
662
663      if (!Section->getBeginSymbol()) {
664        MCSymbol *SectionStartSymbol = getContext().createTempSymbol();
665        getStreamer().emitLabel(SectionStartSymbol);
666        Section->setBeginSymbol(SectionStartSymbol);
667      }
668    }
669  }
670
671  return false;
672}
673
674bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
675  MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
676  if (PreviousSection.first == nullptr)
677      return TokError(".previous without corresponding .section");
678  getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
679
680  return false;
681}
682
683static MCSymbolAttr MCAttrForString(StringRef Type) {
684  return StringSwitch<MCSymbolAttr>(Type)
685          .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
686          .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
687          .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
688          .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
689          .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
690          .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
691                 MCSA_ELF_TypeIndFunction)
692          .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
693          .Default(MCSA_Invalid);
694}
695
696/// ParseDirectiveELFType
697///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
698///  ::= .type identifier , #attribute
699///  ::= .type identifier , @attribute
700///  ::= .type identifier , %attribute
701///  ::= .type identifier , "attribute"
702bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
703  StringRef Name;
704  if (getParser().parseIdentifier(Name))
705    return TokError("expected identifier in directive");
706
707  // Handle the identifier as the key symbol.
708  MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
709
710  // NOTE the comma is optional in all cases.  It is only documented as being
711  // optional in the first case, however, GAS will silently treat the comma as
712  // optional in all cases.  Furthermore, although the documentation states that
713  // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
714  // accepts both the upper case name as well as the lower case aliases.
715  if (getLexer().is(AsmToken::Comma))
716    Lex();
717
718  if (getLexer().isNot(AsmToken::Identifier) &&
719      getLexer().isNot(AsmToken::Hash) &&
720      getLexer().isNot(AsmToken::Percent) &&
721      getLexer().isNot(AsmToken::String)) {
722    if (!getLexer().getAllowAtInIdentifier())
723      return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
724                      "'%<type>' or \"<type>\"");
725    else if (getLexer().isNot(AsmToken::At))
726      return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
727                      "'%<type>' or \"<type>\"");
728  }
729
730  if (getLexer().isNot(AsmToken::String) &&
731      getLexer().isNot(AsmToken::Identifier))
732    Lex();
733
734  SMLoc TypeLoc = getLexer().getLoc();
735
736  StringRef Type;
737  if (getParser().parseIdentifier(Type))
738    return TokError("expected symbol type in directive");
739
740  MCSymbolAttr Attr = MCAttrForString(Type);
741  if (Attr == MCSA_Invalid)
742    return Error(TypeLoc, "unsupported attribute in '.type' directive");
743
744  if (getLexer().isNot(AsmToken::EndOfStatement))
745    return TokError("unexpected token in '.type' directive");
746  Lex();
747
748  getStreamer().emitSymbolAttribute(Sym, Attr);
749
750  return false;
751}
752
753/// ParseDirectiveIdent
754///  ::= .ident string
755bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
756  if (getLexer().isNot(AsmToken::String))
757    return TokError("unexpected token in '.ident' directive");
758
759  StringRef Data = getTok().getIdentifier();
760
761  Lex();
762
763  if (getLexer().isNot(AsmToken::EndOfStatement))
764    return TokError("unexpected token in '.ident' directive");
765  Lex();
766
767  getStreamer().emitIdent(Data);
768  return false;
769}
770
771/// ParseDirectiveSymver
772///  ::= .symver foo, bar2@zed
773bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
774  StringRef Name;
775  if (getParser().parseIdentifier(Name))
776    return TokError("expected identifier in directive");
777
778  if (getLexer().isNot(AsmToken::Comma))
779    return TokError("expected a comma");
780
781  // ARM assembly uses @ for a comment...
782  // except when parsing the second parameter of the .symver directive.
783  // Force the next symbol to allow @ in the identifier, which is
784  // required for this directive and then reset it to its initial state.
785  const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
786  getLexer().setAllowAtInIdentifier(true);
787  Lex();
788  getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
789
790  StringRef AliasName;
791  if (getParser().parseIdentifier(AliasName))
792    return TokError("expected identifier in directive");
793
794  if (AliasName.find('@') == StringRef::npos)
795    return TokError("expected a '@' in the name");
796
797  MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
798  getStreamer().emitELFSymverDirective(AliasName, Sym);
799  return false;
800}
801
802/// ParseDirectiveVersion
803///  ::= .version string
804bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
805  if (getLexer().isNot(AsmToken::String))
806    return TokError("unexpected token in '.version' directive");
807
808  StringRef Data = getTok().getIdentifier();
809
810  Lex();
811
812  MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
813
814  getStreamer().PushSection();
815  getStreamer().SwitchSection(Note);
816  getStreamer().emitInt32(Data.size() + 1); // namesz
817  getStreamer().emitInt32(0);               // descsz = 0 (no description).
818  getStreamer().emitInt32(1);               // type = NT_VERSION
819  getStreamer().emitBytes(Data);            // name
820  getStreamer().emitInt8(0);                // NUL
821  getStreamer().emitValueToAlignment(4);
822  getStreamer().PopSection();
823  return false;
824}
825
826/// ParseDirectiveWeakref
827///  ::= .weakref foo, bar
828bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
829  // FIXME: Share code with the other alias building directives.
830
831  StringRef AliasName;
832  if (getParser().parseIdentifier(AliasName))
833    return TokError("expected identifier in directive");
834
835  if (getLexer().isNot(AsmToken::Comma))
836    return TokError("expected a comma");
837
838  Lex();
839
840  StringRef Name;
841  if (getParser().parseIdentifier(Name))
842    return TokError("expected identifier in directive");
843
844  MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
845
846  MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
847
848  getStreamer().emitWeakReference(Alias, Sym);
849  return false;
850}
851
852bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
853  const MCExpr *Subsection = nullptr;
854  if (getLexer().isNot(AsmToken::EndOfStatement)) {
855    if (getParser().parseExpression(Subsection))
856     return true;
857  }
858
859  if (getLexer().isNot(AsmToken::EndOfStatement))
860    return TokError("unexpected token in directive");
861
862  Lex();
863
864  getStreamer().SubSection(Subsection);
865  return false;
866}
867
868bool ELFAsmParser::ParseDirectiveCGProfile(StringRef S, SMLoc Loc) {
869  return MCAsmParserExtension::ParseDirectiveCGProfile(S, Loc);
870}
871
872namespace llvm {
873
874MCAsmParserExtension *createELFAsmParser() {
875  return new ELFAsmParser;
876}
877
878} // end namespace llvm
879