xref: /llvm-project/llvm/lib/MC/MCParser/ELFAsmParser.cpp (revision c8140d0d7fa943f5ae339cb5e6f4fd8644d5ae89) 
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/StringExtras.h"
10 #include "llvm/ADT/StringRef.h"
11 #include "llvm/ADT/StringSwitch.h"
12 #include "llvm/BinaryFormat/ELF.h"
13 #include "llvm/MC/MCAsmInfo.h"
14 #include "llvm/MC/MCContext.h"
15 #include "llvm/MC/MCDirectives.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/MCSectionELF.h"
20 #include "llvm/MC/MCStreamer.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/MC/MCSymbolELF.h"
23 #include "llvm/MC/SectionKind.h"
24 #include "llvm/Support/Casting.h"
25 #include "llvm/Support/MathExtras.h"
26 #include "llvm/Support/SMLoc.h"
27 #include <cassert>
28 #include <cstdint>
29 #include <utility>
30 
31 using namespace llvm;
32 
33 namespace {
34 
35 class ELFAsmParser : public MCAsmParserExtension {
36   template<bool (ELFAsmParser::*HandlerMethod)(StringRef, SMLoc)>
37   void addDirectiveHandler(StringRef Directive) {
38     MCAsmParser::ExtensionDirectiveHandler Handler = std::make_pair(
39         this, HandleDirective<ELFAsmParser, HandlerMethod>);
40 
41     getParser().addDirectiveHandler(Directive, Handler);
42   }
43 
44   bool parseSectionSwitch(StringRef Section, unsigned Type, unsigned Flags,
45                           SectionKind Kind);
46 
47 public:
48   ELFAsmParser() { BracketExpressionsSupported = true; }
49 
50   void Initialize(MCAsmParser &Parser) override {
51     // Call the base implementation.
52     this->MCAsmParserExtension::Initialize(Parser);
53 
54     addDirectiveHandler<&ELFAsmParser::parseSectionDirectiveData>(".data");
55     addDirectiveHandler<&ELFAsmParser::parseSectionDirectiveText>(".text");
56     addDirectiveHandler<&ELFAsmParser::parseSectionDirectiveBSS>(".bss");
57     addDirectiveHandler<&ELFAsmParser::parseSectionDirectiveRoData>(".rodata");
58     addDirectiveHandler<&ELFAsmParser::parseSectionDirectiveTData>(".tdata");
59     addDirectiveHandler<&ELFAsmParser::parseSectionDirectiveTBSS>(".tbss");
60     addDirectiveHandler<
61       &ELFAsmParser::parseSectionDirectiveDataRel>(".data.rel");
62     addDirectiveHandler<
63       &ELFAsmParser::parseSectionDirectiveDataRelRo>(".data.rel.ro");
64     addDirectiveHandler<
65       &ELFAsmParser::parseSectionDirectiveEhFrame>(".eh_frame");
66     addDirectiveHandler<&ELFAsmParser::parseDirectiveSection>(".section");
67     addDirectiveHandler<
68       &ELFAsmParser::parseDirectivePushSection>(".pushsection");
69     addDirectiveHandler<&ELFAsmParser::parseDirectivePopSection>(".popsection");
70     addDirectiveHandler<&ELFAsmParser::parseDirectiveSize>(".size");
71     addDirectiveHandler<&ELFAsmParser::parseDirectivePrevious>(".previous");
72     addDirectiveHandler<&ELFAsmParser::parseDirectiveType>(".type");
73     addDirectiveHandler<&ELFAsmParser::parseDirectiveIdent>(".ident");
74     addDirectiveHandler<&ELFAsmParser::parseDirectiveSymver>(".symver");
75     addDirectiveHandler<&ELFAsmParser::parseDirectiveVersion>(".version");
76     addDirectiveHandler<&ELFAsmParser::parseDirectiveWeakref>(".weakref");
77     addDirectiveHandler<&ELFAsmParser::parseDirectiveSymbolAttribute>(".weak");
78     addDirectiveHandler<&ELFAsmParser::parseDirectiveSymbolAttribute>(".local");
79     addDirectiveHandler<
80       &ELFAsmParser::parseDirectiveSymbolAttribute>(".protected");
81     addDirectiveHandler<
82       &ELFAsmParser::parseDirectiveSymbolAttribute>(".internal");
83     addDirectiveHandler<
84       &ELFAsmParser::parseDirectiveSymbolAttribute>(".hidden");
85     addDirectiveHandler<&ELFAsmParser::parseDirectiveSubsection>(".subsection");
86     addDirectiveHandler<&ELFAsmParser::parseDirectiveCGProfile>(".cg_profile");
87   }
88 
89   // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
90   // the best way for us to get access to it?
91   bool parseSectionDirectiveData(StringRef, SMLoc) {
92     return parseSectionSwitch(".data", ELF::SHT_PROGBITS,
93                               ELF::SHF_WRITE | ELF::SHF_ALLOC,
94                               SectionKind::getData());
95   }
96   bool parseSectionDirectiveText(StringRef, SMLoc) {
97     return parseSectionSwitch(".text", ELF::SHT_PROGBITS,
98                               ELF::SHF_EXECINSTR |
99                               ELF::SHF_ALLOC, SectionKind::getText());
100   }
101   bool parseSectionDirectiveBSS(StringRef, SMLoc) {
102     return parseSectionSwitch(".bss", ELF::SHT_NOBITS,
103                               ELF::SHF_WRITE |
104                               ELF::SHF_ALLOC, SectionKind::getBSS());
105   }
106   bool parseSectionDirectiveRoData(StringRef, SMLoc) {
107     return parseSectionSwitch(".rodata", ELF::SHT_PROGBITS,
108                               ELF::SHF_ALLOC,
109                               SectionKind::getReadOnly());
110   }
111   bool parseSectionDirectiveTData(StringRef, SMLoc) {
112     return parseSectionSwitch(".tdata", ELF::SHT_PROGBITS,
113                               ELF::SHF_ALLOC |
114                               ELF::SHF_TLS | ELF::SHF_WRITE,
115                               SectionKind::getThreadData());
116   }
117   bool parseSectionDirectiveTBSS(StringRef, SMLoc) {
118     return parseSectionSwitch(".tbss", ELF::SHT_NOBITS,
119                               ELF::SHF_ALLOC |
120                               ELF::SHF_TLS | ELF::SHF_WRITE,
121                               SectionKind::getThreadBSS());
122   }
123   bool parseSectionDirectiveDataRel(StringRef, SMLoc) {
124     return parseSectionSwitch(".data.rel", ELF::SHT_PROGBITS,
125                               ELF::SHF_ALLOC | ELF::SHF_WRITE,
126                               SectionKind::getData());
127   }
128   bool parseSectionDirectiveDataRelRo(StringRef, SMLoc) {
129     return parseSectionSwitch(".data.rel.ro", ELF::SHT_PROGBITS,
130                               ELF::SHF_ALLOC |
131                               ELF::SHF_WRITE,
132                               SectionKind::getReadOnlyWithRel());
133   }
134   bool parseSectionDirectiveEhFrame(StringRef, SMLoc) {
135     return parseSectionSwitch(".eh_frame", ELF::SHT_PROGBITS,
136                               ELF::SHF_ALLOC | ELF::SHF_WRITE,
137                               SectionKind::getData());
138   }
139   bool parseDirectivePushSection(StringRef, SMLoc);
140   bool parseDirectivePopSection(StringRef, SMLoc);
141   bool parseDirectiveSection(StringRef, SMLoc);
142   bool parseDirectiveSize(StringRef, SMLoc);
143   bool parseDirectivePrevious(StringRef, SMLoc);
144   bool parseDirectiveType(StringRef, SMLoc);
145   bool parseDirectiveIdent(StringRef, SMLoc);
146   bool parseDirectiveSymver(StringRef, SMLoc);
147   bool parseDirectiveVersion(StringRef, SMLoc);
148   bool parseDirectiveWeakref(StringRef, SMLoc);
149   bool parseDirectiveSymbolAttribute(StringRef, SMLoc);
150   bool parseDirectiveSubsection(StringRef, SMLoc);
151   bool parseDirectiveCGProfile(StringRef, SMLoc);
152 
153 private:
154   bool parseSectionName(StringRef &SectionName);
155   bool parseSectionArguments(bool IsPush, SMLoc loc);
156   unsigned parseSunStyleSectionFlags();
157   bool maybeParseSectionType(StringRef &TypeName);
158   bool parseMergeSize(int64_t &Size);
159   bool parseGroup(StringRef &GroupName, bool &IsComdat);
160   bool parseLinkedToSym(MCSymbolELF *&LinkedToSym);
161   bool maybeParseUniqueID(int64_t &UniqueID);
162 };
163 
164 } // end anonymous namespace
165 
166 /// parseDirectiveSymbolAttribute
167 ///  ::= { ".local", ".weak", ... } [ identifier ( , identifier )* ]
168 bool ELFAsmParser::parseDirectiveSymbolAttribute(StringRef Directive, SMLoc) {
169   MCSymbolAttr Attr = StringSwitch<MCSymbolAttr>(Directive)
170     .Case(".weak", MCSA_Weak)
171     .Case(".local", MCSA_Local)
172     .Case(".hidden", MCSA_Hidden)
173     .Case(".internal", MCSA_Internal)
174     .Case(".protected", MCSA_Protected)
175     .Default(MCSA_Invalid);
176   assert(Attr != MCSA_Invalid && "unexpected symbol attribute directive!");
177   if (getLexer().isNot(AsmToken::EndOfStatement)) {
178     while (true) {
179       StringRef Name;
180 
181       if (getParser().parseIdentifier(Name))
182         return TokError("expected identifier");
183 
184       if (getParser().discardLTOSymbol(Name)) {
185         if (getLexer().is(AsmToken::EndOfStatement))
186           break;
187         continue;
188       }
189 
190       MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
191 
192       getStreamer().emitSymbolAttribute(Sym, Attr);
193 
194       if (getLexer().is(AsmToken::EndOfStatement))
195         break;
196 
197       if (getLexer().isNot(AsmToken::Comma))
198         return TokError("expected comma");
199       Lex();
200     }
201   }
202 
203   Lex();
204   return false;
205 }
206 
207 bool ELFAsmParser::parseSectionSwitch(StringRef Section, unsigned Type,
208                                       unsigned Flags, SectionKind Kind) {
209   const MCExpr *Subsection = nullptr;
210   if (getLexer().isNot(AsmToken::EndOfStatement)) {
211     if (getParser().parseExpression(Subsection))
212       return true;
213   }
214   Lex();
215 
216   getStreamer().switchSection(getContext().getELFSection(Section, Type, Flags),
217                               Subsection);
218 
219   return false;
220 }
221 
222 bool ELFAsmParser::parseDirectiveSize(StringRef, SMLoc) {
223   StringRef Name;
224   if (getParser().parseIdentifier(Name))
225     return TokError("expected identifier");
226   MCSymbolELF *Sym = cast<MCSymbolELF>(getContext().getOrCreateSymbol(Name));
227 
228   if (getLexer().isNot(AsmToken::Comma))
229     return TokError("expected comma");
230   Lex();
231 
232   const MCExpr *Expr;
233   if (getParser().parseExpression(Expr))
234     return true;
235 
236   if (getLexer().isNot(AsmToken::EndOfStatement))
237     return TokError("unexpected token");
238   Lex();
239 
240   getStreamer().emitELFSize(Sym, Expr);
241   return false;
242 }
243 
244 bool ELFAsmParser::parseSectionName(StringRef &SectionName) {
245   // A section name can contain -, so we cannot just use
246   // parseIdentifier.
247   SMLoc FirstLoc = getLexer().getLoc();
248   unsigned Size = 0;
249 
250   if (getLexer().is(AsmToken::String)) {
251     SectionName = getTok().getIdentifier();
252     Lex();
253     return false;
254   }
255 
256   while (!getParser().hasPendingError()) {
257     SMLoc PrevLoc = getLexer().getLoc();
258     if (getLexer().is(AsmToken::Comma) ||
259       getLexer().is(AsmToken::EndOfStatement))
260       break;
261 
262     unsigned CurSize;
263     if (getLexer().is(AsmToken::String)) {
264       CurSize = getTok().getIdentifier().size() + 2;
265       Lex();
266     } else if (getLexer().is(AsmToken::Identifier)) {
267       CurSize = getTok().getIdentifier().size();
268       Lex();
269     } else {
270       CurSize = getTok().getString().size();
271       Lex();
272     }
273     Size += CurSize;
274     SectionName = StringRef(FirstLoc.getPointer(), Size);
275 
276     // Make sure the following token is adjacent.
277     if (PrevLoc.getPointer() + CurSize != getTok().getLoc().getPointer())
278       break;
279   }
280   if (Size == 0)
281     return true;
282 
283   return false;
284 }
285 
286 static unsigned parseSectionFlags(const Triple &TT, StringRef flagsStr,
287                                   bool *UseLastGroup) {
288   unsigned flags = 0;
289 
290   // If a valid numerical value is set for the section flag, use it verbatim
291   if (!flagsStr.getAsInteger(0, flags))
292     return flags;
293 
294   for (char i : flagsStr) {
295     switch (i) {
296     case 'a':
297       flags |= ELF::SHF_ALLOC;
298       break;
299     case 'e':
300       flags |= ELF::SHF_EXCLUDE;
301       break;
302     case 'x':
303       flags |= ELF::SHF_EXECINSTR;
304       break;
305     case 'w':
306       flags |= ELF::SHF_WRITE;
307       break;
308     case 'o':
309       flags |= ELF::SHF_LINK_ORDER;
310       break;
311     case 'M':
312       flags |= ELF::SHF_MERGE;
313       break;
314     case 'S':
315       flags |= ELF::SHF_STRINGS;
316       break;
317     case 'T':
318       flags |= ELF::SHF_TLS;
319       break;
320     case 'c':
321       if (TT.getArch() != Triple::xcore)
322         return -1U;
323       flags |= ELF::XCORE_SHF_CP_SECTION;
324       break;
325     case 'd':
326       if (TT.getArch() != Triple::xcore)
327         return -1U;
328       flags |= ELF::XCORE_SHF_DP_SECTION;
329       break;
330     case 'y':
331       if (!(TT.isARM() || TT.isThumb()))
332         return -1U;
333       flags |= ELF::SHF_ARM_PURECODE;
334       break;
335     case 's':
336       if (TT.getArch() != Triple::hexagon)
337         return -1U;
338       flags |= ELF::SHF_HEX_GPREL;
339       break;
340     case 'G':
341       flags |= ELF::SHF_GROUP;
342       break;
343     case 'l':
344       if (TT.getArch() != Triple::x86_64)
345         return -1U;
346       flags |= ELF::SHF_X86_64_LARGE;
347       break;
348     case 'R':
349       if (TT.isOSSolaris())
350         flags |= ELF::SHF_SUNW_NODISCARD;
351       else
352         flags |= ELF::SHF_GNU_RETAIN;
353       break;
354     case '?':
355       *UseLastGroup = true;
356       break;
357     default:
358       return -1U;
359     }
360   }
361 
362   return flags;
363 }
364 
365 unsigned ELFAsmParser::parseSunStyleSectionFlags() {
366   unsigned flags = 0;
367   while (getLexer().is(AsmToken::Hash)) {
368     Lex(); // Eat the #.
369 
370     if (!getLexer().is(AsmToken::Identifier))
371       return -1U;
372 
373     StringRef flagId = getTok().getIdentifier();
374     if (flagId == "alloc")
375       flags |= ELF::SHF_ALLOC;
376     else if (flagId == "execinstr")
377       flags |= ELF::SHF_EXECINSTR;
378     else if (flagId == "write")
379       flags |= ELF::SHF_WRITE;
380     else if (flagId == "tls")
381       flags |= ELF::SHF_TLS;
382     else
383       return -1U;
384 
385     Lex(); // Eat the flag.
386 
387     if (!getLexer().is(AsmToken::Comma))
388         break;
389     Lex(); // Eat the comma.
390   }
391   return flags;
392 }
393 
394 
395 bool ELFAsmParser::parseDirectivePushSection(StringRef s, SMLoc loc) {
396   getStreamer().pushSection();
397 
398   if (parseSectionArguments(/*IsPush=*/true, loc)) {
399     getStreamer().popSection();
400     return true;
401   }
402 
403   return false;
404 }
405 
406 bool ELFAsmParser::parseDirectivePopSection(StringRef, SMLoc) {
407   if (!getStreamer().popSection())
408     return TokError(".popsection without corresponding .pushsection");
409   return false;
410 }
411 
412 bool ELFAsmParser::parseDirectiveSection(StringRef, SMLoc loc) {
413   return parseSectionArguments(/*IsPush=*/false, loc);
414 }
415 
416 bool ELFAsmParser::maybeParseSectionType(StringRef &TypeName) {
417   MCAsmLexer &L = getLexer();
418   if (L.isNot(AsmToken::Comma))
419     return false;
420   Lex();
421   if (L.isNot(AsmToken::At) && L.isNot(AsmToken::Percent) &&
422       L.isNot(AsmToken::String)) {
423     if (L.getAllowAtInIdentifier())
424       return TokError("expected '@<type>', '%<type>' or \"<type>\"");
425     else
426       return TokError("expected '%<type>' or \"<type>\"");
427   }
428   if (!L.is(AsmToken::String))
429     Lex();
430   if (L.is(AsmToken::Integer)) {
431     TypeName = getTok().getString();
432     Lex();
433   } else if (getParser().parseIdentifier(TypeName))
434     return TokError("expected identifier");
435   return false;
436 }
437 
438 bool ELFAsmParser::parseMergeSize(int64_t &Size) {
439   if (getLexer().isNot(AsmToken::Comma))
440     return TokError("expected the entry size");
441   Lex();
442   if (getParser().parseAbsoluteExpression(Size))
443     return true;
444   if (Size <= 0)
445     return TokError("entry size must be positive");
446   return false;
447 }
448 
449 bool ELFAsmParser::parseGroup(StringRef &GroupName, bool &IsComdat) {
450   MCAsmLexer &L = getLexer();
451   if (L.isNot(AsmToken::Comma))
452     return TokError("expected group name");
453   Lex();
454   if (L.is(AsmToken::Integer)) {
455     GroupName = getTok().getString();
456     Lex();
457   } else if (getParser().parseIdentifier(GroupName)) {
458     return TokError("invalid group name");
459   }
460   if (L.is(AsmToken::Comma)) {
461     Lex();
462     StringRef Linkage;
463     if (getParser().parseIdentifier(Linkage))
464       return TokError("invalid linkage");
465     if (Linkage != "comdat")
466       return TokError("Linkage must be 'comdat'");
467     IsComdat = true;
468   } else {
469     IsComdat = false;
470   }
471   return false;
472 }
473 
474 bool ELFAsmParser::parseLinkedToSym(MCSymbolELF *&LinkedToSym) {
475   MCAsmLexer &L = getLexer();
476   if (L.isNot(AsmToken::Comma))
477     return TokError("expected linked-to symbol");
478   Lex();
479   StringRef Name;
480   SMLoc StartLoc = L.getLoc();
481   if (getParser().parseIdentifier(Name)) {
482     if (getParser().getTok().getString() == "0") {
483       getParser().Lex();
484       LinkedToSym = nullptr;
485       return false;
486     }
487     return TokError("invalid linked-to symbol");
488   }
489   LinkedToSym = dyn_cast_or_null<MCSymbolELF>(getContext().lookupSymbol(Name));
490   if (!LinkedToSym || !LinkedToSym->isInSection())
491     return Error(StartLoc, "linked-to symbol is not in a section: " + Name);
492   return false;
493 }
494 
495 bool ELFAsmParser::maybeParseUniqueID(int64_t &UniqueID) {
496   MCAsmLexer &L = getLexer();
497   if (L.isNot(AsmToken::Comma))
498     return false;
499   Lex();
500   StringRef UniqueStr;
501   if (getParser().parseIdentifier(UniqueStr))
502     return TokError("expected identifier");
503   if (UniqueStr != "unique")
504     return TokError("expected 'unique'");
505   if (L.isNot(AsmToken::Comma))
506     return TokError("expected commma");
507   Lex();
508   if (getParser().parseAbsoluteExpression(UniqueID))
509     return true;
510   if (UniqueID < 0)
511     return TokError("unique id must be positive");
512   if (!isUInt<32>(UniqueID) || UniqueID == ~0U)
513     return TokError("unique id is too large");
514   return false;
515 }
516 
517 static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
518   return SectionName.consume_front(Prefix) &&
519          (SectionName.empty() || SectionName[0] == '.');
520 }
521 
522 static bool allowSectionTypeMismatch(const Triple &TT, StringRef SectionName,
523                                      unsigned Type) {
524   if (TT.getArch() == Triple::x86_64) {
525     // x86-64 psABI names SHT_X86_64_UNWIND as the canonical type for .eh_frame,
526     // but GNU as emits SHT_PROGBITS .eh_frame for .cfi_* directives. Don't
527     // error for SHT_PROGBITS .eh_frame
528     return SectionName == ".eh_frame" && Type == ELF::SHT_PROGBITS;
529   }
530   if (TT.isMIPS()) {
531     // MIPS .debug_* sections should have SHT_MIPS_DWARF section type to
532     // distinguish among sections contain DWARF and ECOFF debug formats,
533     // but in assembly files these sections have SHT_PROGBITS type.
534     return SectionName.starts_with(".debug_") && Type == ELF::SHT_PROGBITS;
535   }
536   return false;
537 }
538 
539 bool ELFAsmParser::parseSectionArguments(bool IsPush, SMLoc loc) {
540   StringRef SectionName;
541 
542   if (parseSectionName(SectionName))
543     return TokError("expected identifier");
544 
545   StringRef TypeName;
546   int64_t Size = 0;
547   StringRef GroupName;
548   bool IsComdat = false;
549   unsigned Flags = 0;
550   unsigned extraFlags = 0;
551   const MCExpr *Subsection = nullptr;
552   bool UseLastGroup = false;
553   MCSymbolELF *LinkedToSym = nullptr;
554   int64_t UniqueID = ~0;
555 
556   // Set the defaults first.
557   if (hasPrefix(SectionName, ".rodata") || SectionName == ".rodata1")
558     Flags |= ELF::SHF_ALLOC;
559   else if (SectionName == ".fini" || SectionName == ".init" ||
560            hasPrefix(SectionName, ".text"))
561     Flags |= ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
562   else if (hasPrefix(SectionName, ".data") || SectionName == ".data1" ||
563            hasPrefix(SectionName, ".bss") ||
564            hasPrefix(SectionName, ".init_array") ||
565            hasPrefix(SectionName, ".fini_array") ||
566            hasPrefix(SectionName, ".preinit_array"))
567     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE;
568   else if (hasPrefix(SectionName, ".tdata") || hasPrefix(SectionName, ".tbss"))
569     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_TLS;
570 
571   if (getLexer().is(AsmToken::Comma)) {
572     Lex();
573 
574     if (IsPush && getLexer().isNot(AsmToken::String)) {
575       if (getParser().parseExpression(Subsection))
576         return true;
577       if (getLexer().isNot(AsmToken::Comma))
578         goto EndStmt;
579       Lex();
580     }
581 
582     if (getLexer().isNot(AsmToken::String)) {
583       if (getLexer().isNot(AsmToken::Hash))
584         return TokError("expected string");
585       extraFlags = parseSunStyleSectionFlags();
586     } else {
587       StringRef FlagsStr = getTok().getStringContents();
588       Lex();
589       extraFlags = parseSectionFlags(getContext().getTargetTriple(), FlagsStr,
590                                      &UseLastGroup);
591     }
592 
593     if (extraFlags == -1U)
594       return TokError("unknown flag");
595     Flags |= extraFlags;
596 
597     bool Mergeable = Flags & ELF::SHF_MERGE;
598     bool Group = Flags & ELF::SHF_GROUP;
599     if (Group && UseLastGroup)
600       return TokError("Section cannot specifiy a group name while also acting "
601                       "as a member of the last group");
602 
603     if (maybeParseSectionType(TypeName))
604       return true;
605 
606     MCAsmLexer &L = getLexer();
607     if (TypeName.empty()) {
608       if (Mergeable)
609         return TokError("Mergeable section must specify the type");
610       if (Group)
611         return TokError("Group section must specify the type");
612       if (L.isNot(AsmToken::EndOfStatement))
613         return TokError("expected end of directive");
614     }
615 
616     if (Mergeable)
617       if (parseMergeSize(Size))
618         return true;
619     if (Flags & ELF::SHF_LINK_ORDER)
620       if (parseLinkedToSym(LinkedToSym))
621         return true;
622     if (Group)
623       if (parseGroup(GroupName, IsComdat))
624         return true;
625     if (maybeParseUniqueID(UniqueID))
626       return true;
627   }
628 
629 EndStmt:
630   if (getLexer().isNot(AsmToken::EndOfStatement))
631     return TokError("expected end of directive");
632   Lex();
633 
634   unsigned Type = ELF::SHT_PROGBITS;
635 
636   if (TypeName.empty()) {
637     if (SectionName.starts_with(".note"))
638       Type = ELF::SHT_NOTE;
639     else if (hasPrefix(SectionName, ".init_array"))
640       Type = ELF::SHT_INIT_ARRAY;
641     else if (hasPrefix(SectionName, ".bss"))
642       Type = ELF::SHT_NOBITS;
643     else if (hasPrefix(SectionName, ".tbss"))
644       Type = ELF::SHT_NOBITS;
645     else if (hasPrefix(SectionName, ".fini_array"))
646       Type = ELF::SHT_FINI_ARRAY;
647     else if (hasPrefix(SectionName, ".preinit_array"))
648       Type = ELF::SHT_PREINIT_ARRAY;
649   } else {
650     if (TypeName == "init_array")
651       Type = ELF::SHT_INIT_ARRAY;
652     else if (TypeName == "fini_array")
653       Type = ELF::SHT_FINI_ARRAY;
654     else if (TypeName == "preinit_array")
655       Type = ELF::SHT_PREINIT_ARRAY;
656     else if (TypeName == "nobits")
657       Type = ELF::SHT_NOBITS;
658     else if (TypeName == "progbits")
659       Type = ELF::SHT_PROGBITS;
660     else if (TypeName == "note")
661       Type = ELF::SHT_NOTE;
662     else if (TypeName == "unwind")
663       Type = ELF::SHT_X86_64_UNWIND;
664     else if (TypeName == "llvm_odrtab")
665       Type = ELF::SHT_LLVM_ODRTAB;
666     else if (TypeName == "llvm_linker_options")
667       Type = ELF::SHT_LLVM_LINKER_OPTIONS;
668     else if (TypeName == "llvm_call_graph_profile")
669       Type = ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
670     else if (TypeName == "llvm_dependent_libraries")
671       Type = ELF::SHT_LLVM_DEPENDENT_LIBRARIES;
672     else if (TypeName == "llvm_sympart")
673       Type = ELF::SHT_LLVM_SYMPART;
674     else if (TypeName == "llvm_bb_addr_map")
675       Type = ELF::SHT_LLVM_BB_ADDR_MAP;
676     else if (TypeName == "llvm_offloading")
677       Type = ELF::SHT_LLVM_OFFLOADING;
678     else if (TypeName == "llvm_lto")
679       Type = ELF::SHT_LLVM_LTO;
680     else if (TypeName == "llvm_jt_sizes")
681       Type = ELF::SHT_LLVM_JT_SIZES;
682     else if (TypeName.getAsInteger(0, Type))
683       return TokError("unknown section type");
684   }
685 
686   if (UseLastGroup) {
687     if (const MCSectionELF *Section =
688             cast_or_null<MCSectionELF>(getStreamer().getCurrentSectionOnly()))
689       if (const MCSymbol *Group = Section->getGroup()) {
690         GroupName = Group->getName();
691         IsComdat = Section->isComdat();
692         Flags |= ELF::SHF_GROUP;
693       }
694   }
695 
696   MCSectionELF *Section =
697       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
698                                  IsComdat, UniqueID, LinkedToSym);
699   getStreamer().switchSection(Section, Subsection);
700   // Check that flags are used consistently. However, the GNU assembler permits
701   // to leave out in subsequent uses of the same sections; for compatibility,
702   // do likewise.
703   if (!TypeName.empty() && Section->getType() != Type &&
704       !allowSectionTypeMismatch(getContext().getTargetTriple(), SectionName,
705                                 Type))
706     Error(loc, "changed section type for " + SectionName + ", expected: 0x" +
707                    utohexstr(Section->getType()));
708   if ((extraFlags || Size || !TypeName.empty()) && Section->getFlags() != Flags)
709     Error(loc, "changed section flags for " + SectionName + ", expected: 0x" +
710                    utohexstr(Section->getFlags()));
711   if ((extraFlags || Size || !TypeName.empty()) &&
712       Section->getEntrySize() != Size)
713     Error(loc, "changed section entsize for " + SectionName +
714                    ", expected: " + Twine(Section->getEntrySize()));
715 
716   if (getContext().getGenDwarfForAssembly() &&
717       (Section->getFlags() & ELF::SHF_ALLOC) &&
718       (Section->getFlags() & ELF::SHF_EXECINSTR)) {
719     bool InsertResult = getContext().addGenDwarfSection(Section);
720     if (InsertResult && getContext().getDwarfVersion() <= 2)
721       Warning(loc, "DWARF2 only supports one section per compilation unit");
722   }
723 
724   return false;
725 }
726 
727 bool ELFAsmParser::parseDirectivePrevious(StringRef DirName, SMLoc) {
728   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
729   if (PreviousSection.first == nullptr)
730       return TokError(".previous without corresponding .section");
731   getStreamer().switchSection(PreviousSection.first, PreviousSection.second);
732 
733   return false;
734 }
735 
736 static MCSymbolAttr MCAttrForString(StringRef Type) {
737   return StringSwitch<MCSymbolAttr>(Type)
738           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
739           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
740           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
741           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
742           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
743           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
744                  MCSA_ELF_TypeIndFunction)
745           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
746           .Default(MCSA_Invalid);
747 }
748 
749 /// parseDirectiveELFType
750 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
751 ///  ::= .type identifier , #attribute
752 ///  ::= .type identifier , @attribute
753 ///  ::= .type identifier , %attribute
754 ///  ::= .type identifier , "attribute"
755 bool ELFAsmParser::parseDirectiveType(StringRef, SMLoc) {
756   StringRef Name;
757   if (getParser().parseIdentifier(Name))
758     return TokError("expected identifier");
759 
760   // Handle the identifier as the key symbol.
761   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
762 
763   // NOTE the comma is optional in all cases.  It is only documented as being
764   // optional in the first case, however, GAS will silently treat the comma as
765   // optional in all cases.  Furthermore, although the documentation states that
766   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
767   // accepts both the upper case name as well as the lower case aliases.
768   if (getLexer().is(AsmToken::Comma))
769     Lex();
770 
771   if (getLexer().isNot(AsmToken::Identifier) &&
772       getLexer().isNot(AsmToken::Hash) &&
773       getLexer().isNot(AsmToken::Percent) &&
774       getLexer().isNot(AsmToken::String)) {
775     if (!getLexer().getAllowAtInIdentifier())
776       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
777                       "'%<type>' or \"<type>\"");
778     else if (getLexer().isNot(AsmToken::At))
779       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
780                       "'%<type>' or \"<type>\"");
781   }
782 
783   if (getLexer().isNot(AsmToken::String) &&
784       getLexer().isNot(AsmToken::Identifier))
785     Lex();
786 
787   SMLoc TypeLoc = getLexer().getLoc();
788 
789   StringRef Type;
790   if (getParser().parseIdentifier(Type))
791     return TokError("expected symbol type");
792 
793   MCSymbolAttr Attr = MCAttrForString(Type);
794   if (Attr == MCSA_Invalid)
795     return Error(TypeLoc, "unsupported attribute");
796 
797   if (getLexer().isNot(AsmToken::EndOfStatement))
798     return TokError("expected end of directive");
799   Lex();
800 
801   getStreamer().emitSymbolAttribute(Sym, Attr);
802 
803   return false;
804 }
805 
806 /// parseDirectiveIdent
807 ///  ::= .ident string
808 bool ELFAsmParser::parseDirectiveIdent(StringRef, SMLoc) {
809   if (getLexer().isNot(AsmToken::String))
810     return TokError("expected string");
811 
812   StringRef Data = getTok().getIdentifier();
813 
814   Lex();
815 
816   if (getLexer().isNot(AsmToken::EndOfStatement))
817     return TokError("expected end of directive");
818   Lex();
819 
820   getStreamer().emitIdent(Data);
821   return false;
822 }
823 
824 /// parseDirectiveSymver
825 ///  ::= .symver foo, bar2@zed
826 bool ELFAsmParser::parseDirectiveSymver(StringRef, SMLoc) {
827   StringRef OriginalName, Name, Action;
828   if (getParser().parseIdentifier(OriginalName))
829     return TokError("expected identifier");
830 
831   if (getLexer().isNot(AsmToken::Comma))
832     return TokError("expected a comma");
833 
834   // ARM assembly uses @ for a comment...
835   // except when parsing the second parameter of the .symver directive.
836   // Force the next symbol to allow @ in the identifier, which is
837   // required for this directive and then reset it to its initial state.
838   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
839   getLexer().setAllowAtInIdentifier(true);
840   Lex();
841   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
842 
843   if (getParser().parseIdentifier(Name))
844     return TokError("expected identifier");
845 
846   if (!Name.contains('@'))
847     return TokError("expected a '@' in the name");
848   bool KeepOriginalSym = !Name.contains("@@@");
849   if (parseOptionalToken(AsmToken::Comma)) {
850     if (getParser().parseIdentifier(Action) || Action != "remove")
851       return TokError("expected 'remove'");
852     KeepOriginalSym = false;
853   }
854   (void)parseOptionalToken(AsmToken::EndOfStatement);
855 
856   getStreamer().emitELFSymverDirective(
857       getContext().getOrCreateSymbol(OriginalName), Name, KeepOriginalSym);
858   return false;
859 }
860 
861 /// parseDirectiveVersion
862 ///  ::= .version string
863 bool ELFAsmParser::parseDirectiveVersion(StringRef, SMLoc) {
864   if (getLexer().isNot(AsmToken::String))
865     return TokError("expected string");
866 
867   StringRef Data = getTok().getIdentifier();
868 
869   Lex();
870 
871   MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
872 
873   getStreamer().pushSection();
874   getStreamer().switchSection(Note);
875   getStreamer().emitInt32(Data.size() + 1); // namesz
876   getStreamer().emitInt32(0);               // descsz = 0 (no description).
877   getStreamer().emitInt32(1);               // type = NT_VERSION
878   getStreamer().emitBytes(Data);            // name
879   getStreamer().emitInt8(0);                // NUL
880   getStreamer().emitValueToAlignment(Align(4));
881   getStreamer().popSection();
882   return false;
883 }
884 
885 /// parseDirectiveWeakref
886 ///  ::= .weakref foo, bar
887 bool ELFAsmParser::parseDirectiveWeakref(StringRef, SMLoc) {
888   // FIXME: Share code with the other alias building directives.
889 
890   StringRef AliasName;
891   if (getParser().parseIdentifier(AliasName))
892     return TokError("expected identifier");
893 
894   if (getLexer().isNot(AsmToken::Comma))
895     return TokError("expected a comma");
896 
897   Lex();
898 
899   StringRef Name;
900   if (getParser().parseIdentifier(Name))
901     return TokError("expected identifier");
902 
903   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
904 
905   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
906 
907   getStreamer().emitWeakReference(Alias, Sym);
908   return false;
909 }
910 
911 bool ELFAsmParser::parseDirectiveSubsection(StringRef, SMLoc) {
912   const MCExpr *Subsection = MCConstantExpr::create(0, getContext());
913   if (getLexer().isNot(AsmToken::EndOfStatement)) {
914     if (getParser().parseExpression(Subsection))
915      return true;
916   }
917 
918   if (getLexer().isNot(AsmToken::EndOfStatement))
919     return TokError("expected end of directive");
920 
921   Lex();
922 
923   return getStreamer().switchSection(getStreamer().getCurrentSectionOnly(),
924                                      Subsection);
925 }
926 
927 bool ELFAsmParser::parseDirectiveCGProfile(StringRef S, SMLoc Loc) {
928   return MCAsmParserExtension::parseDirectiveCGProfile(S, Loc);
929 }
930 
931 namespace llvm {
932 
933 MCAsmParserExtension *createELFAsmParser() {
934   return new ELFAsmParser;
935 }
936 
937 } // end namespace llvm
938