xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCParser/ELFAsmParser.cpp (revision 0ad011ececb978e22a9bff2acf76633b094f1ff6) 
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.startswith(".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 (Group)
620       if (parseGroup(GroupName, IsComdat))
621         return true;
622     if (Flags & ELF::SHF_LINK_ORDER)
623       if (parseLinkedToSym(LinkedToSym))
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.startswith(".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.getAsInteger(0, Type))
681       return TokError("unknown section type");
682   }
683 
684   if (UseLastGroup) {
685     MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
686     if (const MCSectionELF *Section =
687             cast_or_null<MCSectionELF>(CurrentSection.first))
688       if (const MCSymbol *Group = Section->getGroup()) {
689         GroupName = Group->getName();
690         IsComdat = Section->isComdat();
691         Flags |= ELF::SHF_GROUP;
692       }
693   }
694 
695   MCSectionELF *Section =
696       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
697                                  IsComdat, UniqueID, LinkedToSym);
698   getStreamer().switchSection(Section, Subsection);
699   // Check that flags are used consistently. However, the GNU assembler permits
700   // to leave out in subsequent uses of the same sections; for compatibility,
701   // do likewise.
702   if (!TypeName.empty() && Section->getType() != Type &&
703       !allowSectionTypeMismatch(getContext().getTargetTriple(), SectionName,
704                                 Type))
705     Error(loc, "changed section type for " + SectionName + ", expected: 0x" +
706                    utohexstr(Section->getType()));
707   if ((extraFlags || Size || !TypeName.empty()) && Section->getFlags() != Flags)
708     Error(loc, "changed section flags for " + SectionName + ", expected: 0x" +
709                    utohexstr(Section->getFlags()));
710   if ((extraFlags || Size || !TypeName.empty()) &&
711       Section->getEntrySize() != Size)
712     Error(loc, "changed section entsize for " + SectionName +
713                    ", expected: " + Twine(Section->getEntrySize()));
714 
715   if (getContext().getGenDwarfForAssembly() &&
716       (Section->getFlags() & ELF::SHF_ALLOC) &&
717       (Section->getFlags() & ELF::SHF_EXECINSTR)) {
718     bool InsertResult = getContext().addGenDwarfSection(Section);
719     if (InsertResult) {
720       if (getContext().getDwarfVersion() <= 2)
721         Warning(loc, "DWARF2 only supports one section per compilation unit");
722 
723       if (!Section->getBeginSymbol()) {
724         MCSymbol *SectionStartSymbol = getContext().createTempSymbol();
725         getStreamer().emitLabel(SectionStartSymbol);
726         Section->setBeginSymbol(SectionStartSymbol);
727       }
728     }
729   }
730 
731   return false;
732 }
733 
734 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
735   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
736   if (PreviousSection.first == nullptr)
737       return TokError(".previous without corresponding .section");
738   getStreamer().switchSection(PreviousSection.first, PreviousSection.second);
739 
740   return false;
741 }
742 
743 static MCSymbolAttr MCAttrForString(StringRef Type) {
744   return StringSwitch<MCSymbolAttr>(Type)
745           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
746           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
747           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
748           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
749           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
750           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
751                  MCSA_ELF_TypeIndFunction)
752           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
753           .Default(MCSA_Invalid);
754 }
755 
756 /// ParseDirectiveELFType
757 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
758 ///  ::= .type identifier , #attribute
759 ///  ::= .type identifier , @attribute
760 ///  ::= .type identifier , %attribute
761 ///  ::= .type identifier , "attribute"
762 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
763   StringRef Name;
764   if (getParser().parseIdentifier(Name))
765     return TokError("expected identifier");
766 
767   // Handle the identifier as the key symbol.
768   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
769 
770   // NOTE the comma is optional in all cases.  It is only documented as being
771   // optional in the first case, however, GAS will silently treat the comma as
772   // optional in all cases.  Furthermore, although the documentation states that
773   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
774   // accepts both the upper case name as well as the lower case aliases.
775   if (getLexer().is(AsmToken::Comma))
776     Lex();
777 
778   if (getLexer().isNot(AsmToken::Identifier) &&
779       getLexer().isNot(AsmToken::Hash) &&
780       getLexer().isNot(AsmToken::Percent) &&
781       getLexer().isNot(AsmToken::String)) {
782     if (!getLexer().getAllowAtInIdentifier())
783       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
784                       "'%<type>' or \"<type>\"");
785     else if (getLexer().isNot(AsmToken::At))
786       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
787                       "'%<type>' or \"<type>\"");
788   }
789 
790   if (getLexer().isNot(AsmToken::String) &&
791       getLexer().isNot(AsmToken::Identifier))
792     Lex();
793 
794   SMLoc TypeLoc = getLexer().getLoc();
795 
796   StringRef Type;
797   if (getParser().parseIdentifier(Type))
798     return TokError("expected symbol type");
799 
800   MCSymbolAttr Attr = MCAttrForString(Type);
801   if (Attr == MCSA_Invalid)
802     return Error(TypeLoc, "unsupported attribute");
803 
804   if (getLexer().isNot(AsmToken::EndOfStatement))
805     return TokError("expected end of directive");
806   Lex();
807 
808   getStreamer().emitSymbolAttribute(Sym, Attr);
809 
810   return false;
811 }
812 
813 /// ParseDirectiveIdent
814 ///  ::= .ident string
815 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
816   if (getLexer().isNot(AsmToken::String))
817     return TokError("expected string");
818 
819   StringRef Data = getTok().getIdentifier();
820 
821   Lex();
822 
823   if (getLexer().isNot(AsmToken::EndOfStatement))
824     return TokError("expected end of directive");
825   Lex();
826 
827   getStreamer().emitIdent(Data);
828   return false;
829 }
830 
831 /// ParseDirectiveSymver
832 ///  ::= .symver foo, bar2@zed
833 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
834   StringRef OriginalName, Name, Action;
835   if (getParser().parseIdentifier(OriginalName))
836     return TokError("expected identifier");
837 
838   if (getLexer().isNot(AsmToken::Comma))
839     return TokError("expected a comma");
840 
841   // ARM assembly uses @ for a comment...
842   // except when parsing the second parameter of the .symver directive.
843   // Force the next symbol to allow @ in the identifier, which is
844   // required for this directive and then reset it to its initial state.
845   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
846   getLexer().setAllowAtInIdentifier(true);
847   Lex();
848   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
849 
850   if (getParser().parseIdentifier(Name))
851     return TokError("expected identifier");
852 
853   if (!Name.contains('@'))
854     return TokError("expected a '@' in the name");
855   bool KeepOriginalSym = !Name.contains("@@@");
856   if (parseOptionalToken(AsmToken::Comma)) {
857     if (getParser().parseIdentifier(Action) || Action != "remove")
858       return TokError("expected 'remove'");
859     KeepOriginalSym = false;
860   }
861   (void)parseOptionalToken(AsmToken::EndOfStatement);
862 
863   getStreamer().emitELFSymverDirective(
864       getContext().getOrCreateSymbol(OriginalName), Name, KeepOriginalSym);
865   return false;
866 }
867 
868 /// ParseDirectiveVersion
869 ///  ::= .version string
870 bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
871   if (getLexer().isNot(AsmToken::String))
872     return TokError("expected string");
873 
874   StringRef Data = getTok().getIdentifier();
875 
876   Lex();
877 
878   MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
879 
880   getStreamer().pushSection();
881   getStreamer().switchSection(Note);
882   getStreamer().emitInt32(Data.size() + 1); // namesz
883   getStreamer().emitInt32(0);               // descsz = 0 (no description).
884   getStreamer().emitInt32(1);               // type = NT_VERSION
885   getStreamer().emitBytes(Data);            // name
886   getStreamer().emitInt8(0);                // NUL
887   getStreamer().emitValueToAlignment(Align(4));
888   getStreamer().popSection();
889   return false;
890 }
891 
892 /// ParseDirectiveWeakref
893 ///  ::= .weakref foo, bar
894 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
895   // FIXME: Share code with the other alias building directives.
896 
897   StringRef AliasName;
898   if (getParser().parseIdentifier(AliasName))
899     return TokError("expected identifier");
900 
901   if (getLexer().isNot(AsmToken::Comma))
902     return TokError("expected a comma");
903 
904   Lex();
905 
906   StringRef Name;
907   if (getParser().parseIdentifier(Name))
908     return TokError("expected identifier");
909 
910   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
911 
912   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
913 
914   getStreamer().emitWeakReference(Alias, Sym);
915   return false;
916 }
917 
918 bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
919   const MCExpr *Subsection = nullptr;
920   if (getLexer().isNot(AsmToken::EndOfStatement)) {
921     if (getParser().parseExpression(Subsection))
922      return true;
923   }
924 
925   if (getLexer().isNot(AsmToken::EndOfStatement))
926     return TokError("expected end of directive");
927 
928   Lex();
929 
930   getStreamer().subSection(Subsection);
931   return false;
932 }
933 
934 bool ELFAsmParser::ParseDirectiveCGProfile(StringRef S, SMLoc Loc) {
935   return MCAsmParserExtension::ParseDirectiveCGProfile(S, Loc);
936 }
937 
938 namespace llvm {
939 
940 MCAsmParserExtension *createELFAsmParser() {
941   return new ELFAsmParser;
942 }
943 
944 } // end namespace llvm
945