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