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