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   Lex();
192 
193   getStreamer().SwitchSection(getContext().getELFSection(Section, Type, Flags),
194                               Subsection);
195 
196   return false;
197 }
198 
ParseDirectiveSize(StringRef,SMLoc)199 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
200   StringRef Name;
201   if (getParser().parseIdentifier(Name))
202     return TokError("expected identifier in directive");
203   MCSymbolELF *Sym = cast<MCSymbolELF>(getContext().getOrCreateSymbol(Name));
204 
205   if (getLexer().isNot(AsmToken::Comma))
206     return TokError("unexpected token in directive");
207   Lex();
208 
209   const MCExpr *Expr;
210   if (getParser().parseExpression(Expr))
211     return true;
212 
213   if (getLexer().isNot(AsmToken::EndOfStatement))
214     return TokError("unexpected token in directive");
215 
216   getStreamer().emitELFSize(Sym, Expr);
217   return false;
218 }
219 
ParseSectionName(StringRef & SectionName)220 bool ELFAsmParser::ParseSectionName(StringRef &SectionName) {
221   // A section name can contain -, so we cannot just use
222   // parseIdentifier.
223   SMLoc FirstLoc = getLexer().getLoc();
224   unsigned Size = 0;
225 
226   if (getLexer().is(AsmToken::String)) {
227     SectionName = getTok().getIdentifier();
228     Lex();
229     return false;
230   }
231 
232   for (;;) {
233 
234     SMLoc PrevLoc = getLexer().getLoc();
235     if (getLexer().is(AsmToken::Comma) ||
236       getLexer().is(AsmToken::EndOfStatement))
237       break;
238 
239     unsigned CurSize;
240     if (getLexer().is(AsmToken::String)) {
241       CurSize = getTok().getIdentifier().size() + 2;
242       Lex();
243     } else if (getLexer().is(AsmToken::Identifier)) {
244       CurSize = getTok().getIdentifier().size();
245       Lex();
246     } else {
247       CurSize = getTok().getString().size();
248       Lex();
249     }
250     Size += CurSize;
251     SectionName = StringRef(FirstLoc.getPointer(), Size);
252 
253     // Make sure the following token is adjacent.
254     if (PrevLoc.getPointer() + CurSize != getTok().getLoc().getPointer())
255       break;
256   }
257   if (Size == 0)
258     return true;
259 
260   return false;
261 }
262 
parseSectionFlags(StringRef flagsStr,bool * UseLastGroup)263 static unsigned parseSectionFlags(StringRef flagsStr, bool *UseLastGroup) {
264   unsigned flags = 0;
265 
266   for (char i : flagsStr) {
267     switch (i) {
268     case 'a':
269       flags |= ELF::SHF_ALLOC;
270       break;
271     case 'e':
272       flags |= ELF::SHF_EXCLUDE;
273       break;
274     case 'x':
275       flags |= ELF::SHF_EXECINSTR;
276       break;
277     case 'w':
278       flags |= ELF::SHF_WRITE;
279       break;
280     case 'M':
281       flags |= ELF::SHF_MERGE;
282       break;
283     case 'S':
284       flags |= ELF::SHF_STRINGS;
285       break;
286     case 'T':
287       flags |= ELF::SHF_TLS;
288       break;
289     case 'c':
290       flags |= ELF::XCORE_SHF_CP_SECTION;
291       break;
292     case 'd':
293       flags |= ELF::XCORE_SHF_DP_SECTION;
294       break;
295     case 'G':
296       flags |= ELF::SHF_GROUP;
297       break;
298     case '?':
299       *UseLastGroup = true;
300       break;
301     default:
302       return -1U;
303     }
304   }
305 
306   return flags;
307 }
308 
parseSunStyleSectionFlags()309 unsigned ELFAsmParser::parseSunStyleSectionFlags() {
310   unsigned flags = 0;
311   while (getLexer().is(AsmToken::Hash)) {
312     Lex(); // Eat the #.
313 
314     if (!getLexer().is(AsmToken::Identifier))
315       return -1U;
316 
317     StringRef flagId = getTok().getIdentifier();
318     if (flagId == "alloc")
319       flags |= ELF::SHF_ALLOC;
320     else if (flagId == "execinstr")
321       flags |= ELF::SHF_EXECINSTR;
322     else if (flagId == "write")
323       flags |= ELF::SHF_WRITE;
324     else if (flagId == "tls")
325       flags |= ELF::SHF_TLS;
326     else
327       return -1U;
328 
329     Lex(); // Eat the flag.
330 
331     if (!getLexer().is(AsmToken::Comma))
332         break;
333     Lex(); // Eat the comma.
334   }
335   return flags;
336 }
337 
338 
ParseDirectivePushSection(StringRef s,SMLoc loc)339 bool ELFAsmParser::ParseDirectivePushSection(StringRef s, SMLoc loc) {
340   getStreamer().PushSection();
341 
342   if (ParseSectionArguments(/*IsPush=*/true, loc)) {
343     getStreamer().PopSection();
344     return true;
345   }
346 
347   return false;
348 }
349 
ParseDirectivePopSection(StringRef,SMLoc)350 bool ELFAsmParser::ParseDirectivePopSection(StringRef, SMLoc) {
351   if (!getStreamer().PopSection())
352     return TokError(".popsection without corresponding .pushsection");
353   return false;
354 }
355 
356 // FIXME: This is a work in progress.
ParseDirectiveSection(StringRef,SMLoc loc)357 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc loc) {
358   return ParseSectionArguments(/*IsPush=*/false, loc);
359 }
360 
ParseSectionArguments(bool IsPush,SMLoc loc)361 bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
362   StringRef SectionName;
363 
364   if (ParseSectionName(SectionName))
365     return TokError("expected identifier in directive");
366 
367   StringRef TypeName;
368   int64_t Size = 0;
369   StringRef GroupName;
370   unsigned Flags = 0;
371   const MCExpr *Subsection = nullptr;
372   bool UseLastGroup = false;
373   StringRef UniqueStr;
374   int64_t UniqueID = ~0;
375 
376   // Set the defaults first.
377   if (SectionName == ".fini" || SectionName == ".init" ||
378       SectionName == ".rodata")
379     Flags |= ELF::SHF_ALLOC;
380   if (SectionName == ".fini" || SectionName == ".init")
381     Flags |= ELF::SHF_EXECINSTR;
382 
383   if (getLexer().is(AsmToken::Comma)) {
384     Lex();
385 
386     if (IsPush && getLexer().isNot(AsmToken::String)) {
387       if (getParser().parseExpression(Subsection))
388         return true;
389       if (getLexer().isNot(AsmToken::Comma))
390         goto EndStmt;
391       Lex();
392     }
393 
394     unsigned extraFlags;
395 
396     if (getLexer().isNot(AsmToken::String)) {
397       if (!getContext().getAsmInfo()->usesSunStyleELFSectionSwitchSyntax()
398           || getLexer().isNot(AsmToken::Hash))
399         return TokError("expected string in directive");
400       extraFlags = parseSunStyleSectionFlags();
401     } else {
402       StringRef FlagsStr = getTok().getStringContents();
403       Lex();
404       extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
405     }
406 
407     if (extraFlags == -1U)
408       return TokError("unknown flag");
409     Flags |= extraFlags;
410 
411     bool Mergeable = Flags & ELF::SHF_MERGE;
412     bool Group = Flags & ELF::SHF_GROUP;
413     if (Group && UseLastGroup)
414       return TokError("Section cannot specifiy a group name while also acting "
415                       "as a member of the last group");
416 
417     if (getLexer().isNot(AsmToken::Comma)) {
418       if (Mergeable)
419         return TokError("Mergeable section must specify the type");
420       if (Group)
421         return TokError("Group section must specify the type");
422     } else {
423       Lex();
424       if (getLexer().is(AsmToken::At) || getLexer().is(AsmToken::Percent) ||
425           getLexer().is(AsmToken::String)) {
426         if (!getLexer().is(AsmToken::String))
427           Lex();
428       } else
429         return TokError("expected '@<type>', '%<type>' or \"<type>\"");
430 
431       if (getParser().parseIdentifier(TypeName))
432         return TokError("expected identifier in directive");
433 
434       if (Mergeable) {
435         if (getLexer().isNot(AsmToken::Comma))
436           return TokError("expected the entry size");
437         Lex();
438         if (getParser().parseAbsoluteExpression(Size))
439           return true;
440         if (Size <= 0)
441           return TokError("entry size must be positive");
442       }
443 
444       if (Group) {
445         if (getLexer().isNot(AsmToken::Comma))
446           return TokError("expected group name");
447         Lex();
448         if (getParser().parseIdentifier(GroupName))
449           return true;
450         if (getLexer().is(AsmToken::Comma)) {
451           Lex();
452           StringRef Linkage;
453           if (getParser().parseIdentifier(Linkage))
454             return true;
455           if (Linkage != "comdat")
456             return TokError("Linkage must be 'comdat'");
457         }
458       }
459       if (getLexer().is(AsmToken::Comma)) {
460         Lex();
461         if (getParser().parseIdentifier(UniqueStr))
462           return TokError("expected identifier in directive");
463         if (UniqueStr != "unique")
464           return TokError("expected 'unique'");
465         if (getLexer().isNot(AsmToken::Comma))
466           return TokError("expected commma");
467         Lex();
468         if (getParser().parseAbsoluteExpression(UniqueID))
469           return true;
470         if (UniqueID < 0)
471           return TokError("unique id must be positive");
472         if (!isUInt<32>(UniqueID) || UniqueID == ~0U)
473           return TokError("unique id is too large");
474       }
475     }
476   }
477 
478 EndStmt:
479   if (getLexer().isNot(AsmToken::EndOfStatement))
480     return TokError("unexpected token in directive");
481 
482   unsigned Type = ELF::SHT_PROGBITS;
483 
484   if (TypeName.empty()) {
485     if (SectionName.startswith(".note"))
486       Type = ELF::SHT_NOTE;
487     else if (SectionName == ".init_array")
488       Type = ELF::SHT_INIT_ARRAY;
489     else if (SectionName == ".fini_array")
490       Type = ELF::SHT_FINI_ARRAY;
491     else if (SectionName == ".preinit_array")
492       Type = ELF::SHT_PREINIT_ARRAY;
493   } else {
494     if (TypeName == "init_array")
495       Type = ELF::SHT_INIT_ARRAY;
496     else if (TypeName == "fini_array")
497       Type = ELF::SHT_FINI_ARRAY;
498     else if (TypeName == "preinit_array")
499       Type = ELF::SHT_PREINIT_ARRAY;
500     else if (TypeName == "nobits")
501       Type = ELF::SHT_NOBITS;
502     else if (TypeName == "progbits")
503       Type = ELF::SHT_PROGBITS;
504     else if (TypeName == "note")
505       Type = ELF::SHT_NOTE;
506     else if (TypeName == "unwind")
507       Type = ELF::SHT_X86_64_UNWIND;
508     else
509       return TokError("unknown section type");
510   }
511 
512   if (UseLastGroup) {
513     MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
514     if (const MCSectionELF *Section =
515             cast_or_null<MCSectionELF>(CurrentSection.first))
516       if (const MCSymbol *Group = Section->getGroup()) {
517         GroupName = Group->getName();
518         Flags |= ELF::SHF_GROUP;
519       }
520   }
521 
522   MCSection *ELFSection = getContext().getELFSection(SectionName, Type, Flags,
523                                                      Size, GroupName, UniqueID);
524   getStreamer().SwitchSection(ELFSection, Subsection);
525 
526   if (getContext().getGenDwarfForAssembly()) {
527     bool InsertResult = getContext().addGenDwarfSection(ELFSection);
528     if (InsertResult) {
529       if (getContext().getDwarfVersion() <= 2)
530         Warning(loc, "DWARF2 only supports one section per compilation unit");
531 
532       if (!ELFSection->getBeginSymbol()) {
533         MCSymbol *SectionStartSymbol = getContext().createTempSymbol();
534         getStreamer().EmitLabel(SectionStartSymbol);
535         ELFSection->setBeginSymbol(SectionStartSymbol);
536       }
537     }
538   }
539 
540   return false;
541 }
542 
ParseDirectivePrevious(StringRef DirName,SMLoc)543 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
544   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
545   if (PreviousSection.first == nullptr)
546       return TokError(".previous without corresponding .section");
547   getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
548 
549   return false;
550 }
551 
MCAttrForString(StringRef Type)552 static MCSymbolAttr MCAttrForString(StringRef Type) {
553   return StringSwitch<MCSymbolAttr>(Type)
554           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
555           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
556           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
557           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
558           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
559           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
560                  MCSA_ELF_TypeIndFunction)
561           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
562           .Default(MCSA_Invalid);
563 }
564 
565 /// ParseDirectiveELFType
566 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
567 ///  ::= .type identifier , #attribute
568 ///  ::= .type identifier , @attribute
569 ///  ::= .type identifier , %attribute
570 ///  ::= .type identifier , "attribute"
ParseDirectiveType(StringRef,SMLoc)571 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
572   StringRef Name;
573   if (getParser().parseIdentifier(Name))
574     return TokError("expected identifier in directive");
575 
576   // Handle the identifier as the key symbol.
577   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
578 
579   // NOTE the comma is optional in all cases.  It is only documented as being
580   // optional in the first case, however, GAS will silently treat the comma as
581   // optional in all cases.  Furthermore, although the documentation states that
582   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
583   // accepts both the upper case name as well as the lower case aliases.
584   if (getLexer().is(AsmToken::Comma))
585     Lex();
586 
587   if (getLexer().isNot(AsmToken::Identifier) &&
588       getLexer().isNot(AsmToken::Hash) &&
589       getLexer().isNot(AsmToken::Percent) &&
590       getLexer().isNot(AsmToken::String)) {
591     if (!getLexer().getAllowAtInIdentifier())
592       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
593                       "'%<type>' or \"<type>\"");
594     else if (getLexer().isNot(AsmToken::At))
595       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
596                       "'%<type>' or \"<type>\"");
597   }
598 
599   if (getLexer().isNot(AsmToken::String) &&
600       getLexer().isNot(AsmToken::Identifier))
601     Lex();
602 
603   SMLoc TypeLoc = getLexer().getLoc();
604 
605   StringRef Type;
606   if (getParser().parseIdentifier(Type))
607     return TokError("expected symbol type in directive");
608 
609   MCSymbolAttr Attr = MCAttrForString(Type);
610   if (Attr == MCSA_Invalid)
611     return Error(TypeLoc, "unsupported attribute in '.type' directive");
612 
613   if (getLexer().isNot(AsmToken::EndOfStatement))
614     return TokError("unexpected token in '.type' directive");
615   Lex();
616 
617   getStreamer().EmitSymbolAttribute(Sym, Attr);
618 
619   return false;
620 }
621 
622 /// ParseDirectiveIdent
623 ///  ::= .ident string
ParseDirectiveIdent(StringRef,SMLoc)624 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
625   if (getLexer().isNot(AsmToken::String))
626     return TokError("unexpected token in '.ident' directive");
627 
628   StringRef Data = getTok().getIdentifier();
629 
630   Lex();
631 
632   getStreamer().EmitIdent(Data);
633   return false;
634 }
635 
636 /// ParseDirectiveSymver
637 ///  ::= .symver foo, bar2@zed
ParseDirectiveSymver(StringRef,SMLoc)638 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
639   StringRef Name;
640   if (getParser().parseIdentifier(Name))
641     return TokError("expected identifier in directive");
642 
643   if (getLexer().isNot(AsmToken::Comma))
644     return TokError("expected a comma");
645 
646   // ARM assembly uses @ for a comment...
647   // except when parsing the second parameter of the .symver directive.
648   // Force the next symbol to allow @ in the identifier, which is
649   // required for this directive and then reset it to its initial state.
650   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
651   getLexer().setAllowAtInIdentifier(true);
652   Lex();
653   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
654 
655   StringRef AliasName;
656   if (getParser().parseIdentifier(AliasName))
657     return TokError("expected identifier in directive");
658 
659   if (AliasName.find('@') == StringRef::npos)
660     return TokError("expected a '@' in the name");
661 
662   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
663   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
664   const MCExpr *Value = MCSymbolRefExpr::create(Sym, getContext());
665 
666   getStreamer().EmitAssignment(Alias, Value);
667   return false;
668 }
669 
670 /// ParseDirectiveVersion
671 ///  ::= .version string
ParseDirectiveVersion(StringRef,SMLoc)672 bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
673   if (getLexer().isNot(AsmToken::String))
674     return TokError("unexpected token in '.version' directive");
675 
676   StringRef Data = getTok().getIdentifier();
677 
678   Lex();
679 
680   MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
681 
682   getStreamer().PushSection();
683   getStreamer().SwitchSection(Note);
684   getStreamer().EmitIntValue(Data.size()+1, 4); // namesz.
685   getStreamer().EmitIntValue(0, 4);             // descsz = 0 (no description).
686   getStreamer().EmitIntValue(1, 4);             // type = NT_VERSION.
687   getStreamer().EmitBytes(Data);                // name.
688   getStreamer().EmitIntValue(0, 1);             // terminate the string.
689   getStreamer().EmitValueToAlignment(4);        // ensure 4 byte alignment.
690   getStreamer().PopSection();
691   return false;
692 }
693 
694 /// ParseDirectiveWeakref
695 ///  ::= .weakref foo, bar
ParseDirectiveWeakref(StringRef,SMLoc)696 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
697   // FIXME: Share code with the other alias building directives.
698 
699   StringRef AliasName;
700   if (getParser().parseIdentifier(AliasName))
701     return TokError("expected identifier in directive");
702 
703   if (getLexer().isNot(AsmToken::Comma))
704     return TokError("expected a comma");
705 
706   Lex();
707 
708   StringRef Name;
709   if (getParser().parseIdentifier(Name))
710     return TokError("expected identifier in directive");
711 
712   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
713 
714   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
715 
716   getStreamer().EmitWeakReference(Alias, Sym);
717   return false;
718 }
719 
ParseDirectiveSubsection(StringRef,SMLoc)720 bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
721   const MCExpr *Subsection = nullptr;
722   if (getLexer().isNot(AsmToken::EndOfStatement)) {
723     if (getParser().parseExpression(Subsection))
724      return true;
725   }
726 
727   if (getLexer().isNot(AsmToken::EndOfStatement))
728     return TokError("unexpected token in directive");
729 
730   getStreamer().SubSection(Subsection);
731   return false;
732 }
733 
734 namespace llvm {
735 
createELFAsmParser()736 MCAsmParserExtension *createELFAsmParser() {
737   return new ELFAsmParser;
738 }
739 
740 }
741