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 's':
325       flags |= ELF::SHF_HEX_GPREL;
326       break;
327     case 'G':
328       flags |= ELF::SHF_GROUP;
329       break;
330     case '?':
331       *UseLastGroup = true;
332       break;
333     default:
334       return -1U;
335     }
336   }
337 
338   return flags;
339 }
340 
341 unsigned ELFAsmParser::parseSunStyleSectionFlags() {
342   unsigned flags = 0;
343   while (getLexer().is(AsmToken::Hash)) {
344     Lex(); // Eat the #.
345 
346     if (!getLexer().is(AsmToken::Identifier))
347       return -1U;
348 
349     StringRef flagId = getTok().getIdentifier();
350     if (flagId == "alloc")
351       flags |= ELF::SHF_ALLOC;
352     else if (flagId == "execinstr")
353       flags |= ELF::SHF_EXECINSTR;
354     else if (flagId == "write")
355       flags |= ELF::SHF_WRITE;
356     else if (flagId == "tls")
357       flags |= ELF::SHF_TLS;
358     else
359       return -1U;
360 
361     Lex(); // Eat the flag.
362 
363     if (!getLexer().is(AsmToken::Comma))
364         break;
365     Lex(); // Eat the comma.
366   }
367   return flags;
368 }
369 
370 
371 bool ELFAsmParser::ParseDirectivePushSection(StringRef s, SMLoc loc) {
372   getStreamer().PushSection();
373 
374   if (ParseSectionArguments(/*IsPush=*/true, loc)) {
375     getStreamer().PopSection();
376     return true;
377   }
378 
379   return false;
380 }
381 
382 bool ELFAsmParser::ParseDirectivePopSection(StringRef, SMLoc) {
383   if (!getStreamer().PopSection())
384     return TokError(".popsection without corresponding .pushsection");
385   return false;
386 }
387 
388 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc loc) {
389   return ParseSectionArguments(/*IsPush=*/false, loc);
390 }
391 
392 bool ELFAsmParser::maybeParseSectionType(StringRef &TypeName) {
393   MCAsmLexer &L = getLexer();
394   if (L.isNot(AsmToken::Comma))
395     return false;
396   Lex();
397   if (L.isNot(AsmToken::At) && L.isNot(AsmToken::Percent) &&
398       L.isNot(AsmToken::String)) {
399     if (L.getAllowAtInIdentifier())
400       return TokError("expected '@<type>', '%<type>' or \"<type>\"");
401     else
402       return TokError("expected '%<type>' or \"<type>\"");
403   }
404   if (!L.is(AsmToken::String))
405     Lex();
406   if (L.is(AsmToken::Integer)) {
407     TypeName = getTok().getString();
408     Lex();
409   } else if (getParser().parseIdentifier(TypeName))
410     return TokError("expected identifier in directive");
411   return false;
412 }
413 
414 bool ELFAsmParser::parseMergeSize(int64_t &Size) {
415   if (getLexer().isNot(AsmToken::Comma))
416     return TokError("expected the entry size");
417   Lex();
418   if (getParser().parseAbsoluteExpression(Size))
419     return true;
420   if (Size <= 0)
421     return TokError("entry size must be positive");
422   return false;
423 }
424 
425 bool ELFAsmParser::parseGroup(StringRef &GroupName) {
426   MCAsmLexer &L = getLexer();
427   if (L.isNot(AsmToken::Comma))
428     return TokError("expected group name");
429   Lex();
430   if (L.is(AsmToken::Integer)) {
431     GroupName = getTok().getString();
432     Lex();
433   } else if (getParser().parseIdentifier(GroupName)) {
434     return TokError("invalid group name");
435   }
436   if (L.is(AsmToken::Comma)) {
437     Lex();
438     StringRef Linkage;
439     if (getParser().parseIdentifier(Linkage))
440       return TokError("invalid linkage");
441     if (Linkage != "comdat")
442       return TokError("Linkage must be 'comdat'");
443   }
444   return false;
445 }
446 
447 bool ELFAsmParser::parseMetadataSym(MCSymbolELF *&Associated) {
448   MCAsmLexer &L = getLexer();
449   if (L.isNot(AsmToken::Comma))
450     return TokError("expected metadata symbol");
451   Lex();
452   StringRef Name;
453   if (getParser().parseIdentifier(Name))
454     return TokError("invalid metadata symbol");
455   Associated = dyn_cast_or_null<MCSymbolELF>(getContext().lookupSymbol(Name));
456   if (!Associated || !Associated->isInSection())
457     return TokError("symbol is not in a section: " + Name);
458   return false;
459 }
460 
461 bool ELFAsmParser::maybeParseUniqueID(int64_t &UniqueID) {
462   MCAsmLexer &L = getLexer();
463   if (L.isNot(AsmToken::Comma))
464     return false;
465   Lex();
466   StringRef UniqueStr;
467   if (getParser().parseIdentifier(UniqueStr))
468     return TokError("expected identifier in directive");
469   if (UniqueStr != "unique")
470     return TokError("expected 'unique'");
471   if (L.isNot(AsmToken::Comma))
472     return TokError("expected commma");
473   Lex();
474   if (getParser().parseAbsoluteExpression(UniqueID))
475     return true;
476   if (UniqueID < 0)
477     return TokError("unique id must be positive");
478   if (!isUInt<32>(UniqueID) || UniqueID == ~0U)
479     return TokError("unique id is too large");
480   return false;
481 }
482 
483 static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
484   return SectionName.startswith(Prefix) || SectionName == Prefix.drop_back();
485 }
486 
487 bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
488   StringRef SectionName;
489 
490   if (ParseSectionName(SectionName))
491     return TokError("expected identifier in directive");
492 
493   StringRef TypeName;
494   int64_t Size = 0;
495   StringRef GroupName;
496   unsigned Flags = 0;
497   const MCExpr *Subsection = nullptr;
498   bool UseLastGroup = false;
499   MCSymbolELF *Associated = nullptr;
500   int64_t UniqueID = ~0;
501 
502   // Set the defaults first.
503   if (hasPrefix(SectionName, ".rodata.") || SectionName == ".rodata1")
504     Flags |= ELF::SHF_ALLOC;
505   else if (SectionName == ".fini" || SectionName == ".init" ||
506            hasPrefix(SectionName, ".text."))
507     Flags |= ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
508   else if (hasPrefix(SectionName, ".data.") || SectionName == ".data1" ||
509            hasPrefix(SectionName, ".bss.") ||
510            hasPrefix(SectionName, ".init_array.") ||
511            hasPrefix(SectionName, ".fini_array.") ||
512            hasPrefix(SectionName, ".preinit_array."))
513     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE;
514   else if (hasPrefix(SectionName, ".tdata.") ||
515            hasPrefix(SectionName, ".tbss."))
516     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_TLS;
517 
518   if (getLexer().is(AsmToken::Comma)) {
519     Lex();
520 
521     if (IsPush && getLexer().isNot(AsmToken::String)) {
522       if (getParser().parseExpression(Subsection))
523         return true;
524       if (getLexer().isNot(AsmToken::Comma))
525         goto EndStmt;
526       Lex();
527     }
528 
529     unsigned extraFlags;
530 
531     if (getLexer().isNot(AsmToken::String)) {
532       if (!getContext().getAsmInfo()->usesSunStyleELFSectionSwitchSyntax()
533           || getLexer().isNot(AsmToken::Hash))
534         return TokError("expected string in directive");
535       extraFlags = parseSunStyleSectionFlags();
536     } else {
537       StringRef FlagsStr = getTok().getStringContents();
538       Lex();
539       extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
540     }
541 
542     if (extraFlags == -1U)
543       return TokError("unknown flag");
544     Flags |= extraFlags;
545 
546     bool Mergeable = Flags & ELF::SHF_MERGE;
547     bool Group = Flags & ELF::SHF_GROUP;
548     if (Group && UseLastGroup)
549       return TokError("Section cannot specifiy a group name while also acting "
550                       "as a member of the last group");
551 
552     if (maybeParseSectionType(TypeName))
553       return true;
554 
555     MCAsmLexer &L = getLexer();
556     if (TypeName.empty()) {
557       if (Mergeable)
558         return TokError("Mergeable section must specify the type");
559       if (Group)
560         return TokError("Group section must specify the type");
561       if (L.isNot(AsmToken::EndOfStatement))
562         return TokError("unexpected token in directive");
563     }
564 
565     if (Mergeable)
566       if (parseMergeSize(Size))
567         return true;
568     if (Group)
569       if (parseGroup(GroupName))
570         return true;
571     if (Flags & ELF::SHF_LINK_ORDER)
572       if (parseMetadataSym(Associated))
573         return true;
574     if (maybeParseUniqueID(UniqueID))
575       return true;
576   }
577 
578 EndStmt:
579   if (getLexer().isNot(AsmToken::EndOfStatement))
580     return TokError("unexpected token in directive");
581   Lex();
582 
583   unsigned Type = ELF::SHT_PROGBITS;
584 
585   if (TypeName.empty()) {
586     if (SectionName.startswith(".note"))
587       Type = ELF::SHT_NOTE;
588     else if (hasPrefix(SectionName, ".init_array."))
589       Type = ELF::SHT_INIT_ARRAY;
590     else if (hasPrefix(SectionName, ".bss."))
591       Type = ELF::SHT_NOBITS;
592     else if (hasPrefix(SectionName, ".tbss."))
593       Type = ELF::SHT_NOBITS;
594     else if (hasPrefix(SectionName, ".fini_array."))
595       Type = ELF::SHT_FINI_ARRAY;
596     else if (hasPrefix(SectionName, ".preinit_array."))
597       Type = ELF::SHT_PREINIT_ARRAY;
598   } else {
599     if (TypeName == "init_array")
600       Type = ELF::SHT_INIT_ARRAY;
601     else if (TypeName == "fini_array")
602       Type = ELF::SHT_FINI_ARRAY;
603     else if (TypeName == "preinit_array")
604       Type = ELF::SHT_PREINIT_ARRAY;
605     else if (TypeName == "nobits")
606       Type = ELF::SHT_NOBITS;
607     else if (TypeName == "progbits")
608       Type = ELF::SHT_PROGBITS;
609     else if (TypeName == "note")
610       Type = ELF::SHT_NOTE;
611     else if (TypeName == "unwind")
612       Type = ELF::SHT_X86_64_UNWIND;
613     else if (TypeName == "llvm_odrtab")
614       Type = ELF::SHT_LLVM_ODRTAB;
615     else if (TypeName == "llvm_linker_options")
616       Type = ELF::SHT_LLVM_LINKER_OPTIONS;
617     else if (TypeName == "llvm_call_graph_profile")
618       Type = ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
619     else if (TypeName.getAsInteger(0, Type))
620       return TokError("unknown section type");
621   }
622 
623   if (UseLastGroup) {
624     MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
625     if (const MCSectionELF *Section =
626             cast_or_null<MCSectionELF>(CurrentSection.first))
627       if (const MCSymbol *Group = Section->getGroup()) {
628         GroupName = Group->getName();
629         Flags |= ELF::SHF_GROUP;
630       }
631   }
632 
633   MCSection *ELFSection =
634       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
635                                  UniqueID, Associated);
636   getStreamer().SwitchSection(ELFSection, Subsection);
637 
638   if (getContext().getGenDwarfForAssembly()) {
639     bool InsertResult = getContext().addGenDwarfSection(ELFSection);
640     if (InsertResult) {
641       if (getContext().getDwarfVersion() <= 2)
642         Warning(loc, "DWARF2 only supports one section per compilation unit");
643 
644       if (!ELFSection->getBeginSymbol()) {
645         MCSymbol *SectionStartSymbol = getContext().createTempSymbol();
646         getStreamer().EmitLabel(SectionStartSymbol);
647         ELFSection->setBeginSymbol(SectionStartSymbol);
648       }
649     }
650   }
651 
652   return false;
653 }
654 
655 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
656   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
657   if (PreviousSection.first == nullptr)
658       return TokError(".previous without corresponding .section");
659   getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
660 
661   return false;
662 }
663 
664 static MCSymbolAttr MCAttrForString(StringRef Type) {
665   return StringSwitch<MCSymbolAttr>(Type)
666           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
667           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
668           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
669           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
670           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
671           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
672                  MCSA_ELF_TypeIndFunction)
673           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
674           .Default(MCSA_Invalid);
675 }
676 
677 /// ParseDirectiveELFType
678 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
679 ///  ::= .type identifier , #attribute
680 ///  ::= .type identifier , @attribute
681 ///  ::= .type identifier , %attribute
682 ///  ::= .type identifier , "attribute"
683 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
684   StringRef Name;
685   if (getParser().parseIdentifier(Name))
686     return TokError("expected identifier in directive");
687 
688   // Handle the identifier as the key symbol.
689   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
690 
691   // NOTE the comma is optional in all cases.  It is only documented as being
692   // optional in the first case, however, GAS will silently treat the comma as
693   // optional in all cases.  Furthermore, although the documentation states that
694   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
695   // accepts both the upper case name as well as the lower case aliases.
696   if (getLexer().is(AsmToken::Comma))
697     Lex();
698 
699   if (getLexer().isNot(AsmToken::Identifier) &&
700       getLexer().isNot(AsmToken::Hash) &&
701       getLexer().isNot(AsmToken::Percent) &&
702       getLexer().isNot(AsmToken::String)) {
703     if (!getLexer().getAllowAtInIdentifier())
704       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
705                       "'%<type>' or \"<type>\"");
706     else if (getLexer().isNot(AsmToken::At))
707       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
708                       "'%<type>' or \"<type>\"");
709   }
710 
711   if (getLexer().isNot(AsmToken::String) &&
712       getLexer().isNot(AsmToken::Identifier))
713     Lex();
714 
715   SMLoc TypeLoc = getLexer().getLoc();
716 
717   StringRef Type;
718   if (getParser().parseIdentifier(Type))
719     return TokError("expected symbol type in directive");
720 
721   MCSymbolAttr Attr = MCAttrForString(Type);
722   if (Attr == MCSA_Invalid)
723     return Error(TypeLoc, "unsupported attribute in '.type' directive");
724 
725   if (getLexer().isNot(AsmToken::EndOfStatement))
726     return TokError("unexpected token in '.type' directive");
727   Lex();
728 
729   getStreamer().EmitSymbolAttribute(Sym, Attr);
730 
731   return false;
732 }
733 
734 /// ParseDirectiveIdent
735 ///  ::= .ident string
736 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
737   if (getLexer().isNot(AsmToken::String))
738     return TokError("unexpected token in '.ident' directive");
739 
740   StringRef Data = getTok().getIdentifier();
741 
742   Lex();
743 
744   if (getLexer().isNot(AsmToken::EndOfStatement))
745     return TokError("unexpected token in '.ident' directive");
746   Lex();
747 
748   getStreamer().EmitIdent(Data);
749   return false;
750 }
751 
752 /// ParseDirectiveSymver
753 ///  ::= .symver foo, bar2@zed
754 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
755   StringRef Name;
756   if (getParser().parseIdentifier(Name))
757     return TokError("expected identifier in directive");
758 
759   if (getLexer().isNot(AsmToken::Comma))
760     return TokError("expected a comma");
761 
762   // ARM assembly uses @ for a comment...
763   // except when parsing the second parameter of the .symver directive.
764   // Force the next symbol to allow @ in the identifier, which is
765   // required for this directive and then reset it to its initial state.
766   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
767   getLexer().setAllowAtInIdentifier(true);
768   Lex();
769   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
770 
771   StringRef AliasName;
772   if (getParser().parseIdentifier(AliasName))
773     return TokError("expected identifier in directive");
774 
775   if (AliasName.find('@') == StringRef::npos)
776     return TokError("expected a '@' in the name");
777 
778   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
779   getStreamer().emitELFSymverDirective(AliasName, Sym);
780   return false;
781 }
782 
783 /// ParseDirectiveVersion
784 ///  ::= .version string
785 bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
786   if (getLexer().isNot(AsmToken::String))
787     return TokError("unexpected token in '.version' directive");
788 
789   StringRef Data = getTok().getIdentifier();
790 
791   Lex();
792 
793   MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
794 
795   getStreamer().PushSection();
796   getStreamer().SwitchSection(Note);
797   getStreamer().EmitIntValue(Data.size()+1, 4); // namesz.
798   getStreamer().EmitIntValue(0, 4);             // descsz = 0 (no description).
799   getStreamer().EmitIntValue(1, 4);             // type = NT_VERSION.
800   getStreamer().EmitBytes(Data);                // name.
801   getStreamer().EmitIntValue(0, 1);             // terminate the string.
802   getStreamer().EmitValueToAlignment(4);        // ensure 4 byte alignment.
803   getStreamer().PopSection();
804   return false;
805 }
806 
807 /// ParseDirectiveWeakref
808 ///  ::= .weakref foo, bar
809 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
810   // FIXME: Share code with the other alias building directives.
811 
812   StringRef AliasName;
813   if (getParser().parseIdentifier(AliasName))
814     return TokError("expected identifier in directive");
815 
816   if (getLexer().isNot(AsmToken::Comma))
817     return TokError("expected a comma");
818 
819   Lex();
820 
821   StringRef Name;
822   if (getParser().parseIdentifier(Name))
823     return TokError("expected identifier in directive");
824 
825   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
826 
827   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
828 
829   getStreamer().EmitWeakReference(Alias, Sym);
830   return false;
831 }
832 
833 bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
834   const MCExpr *Subsection = nullptr;
835   if (getLexer().isNot(AsmToken::EndOfStatement)) {
836     if (getParser().parseExpression(Subsection))
837      return true;
838   }
839 
840   if (getLexer().isNot(AsmToken::EndOfStatement))
841     return TokError("unexpected token in directive");
842 
843   Lex();
844 
845   getStreamer().SubSection(Subsection);
846   return false;
847 }
848 
849 /// ParseDirectiveCGProfile
850 ///  ::= .cg_profile identifier, identifier, <number>
851 bool ELFAsmParser::ParseDirectiveCGProfile(StringRef, SMLoc) {
852   StringRef From;
853   SMLoc FromLoc = getLexer().getLoc();
854   if (getParser().parseIdentifier(From))
855     return TokError("expected identifier in directive");
856 
857   if (getLexer().isNot(AsmToken::Comma))
858     return TokError("expected a comma");
859   Lex();
860 
861   StringRef To;
862   SMLoc ToLoc = getLexer().getLoc();
863   if (getParser().parseIdentifier(To))
864     return TokError("expected identifier in directive");
865 
866   if (getLexer().isNot(AsmToken::Comma))
867     return TokError("expected a comma");
868   Lex();
869 
870   int64_t Count;
871   if (getParser().parseIntToken(
872           Count, "expected integer count in '.cg_profile' directive"))
873     return true;
874 
875   if (getLexer().isNot(AsmToken::EndOfStatement))
876     return TokError("unexpected token in directive");
877 
878   MCSymbol *FromSym = getContext().getOrCreateSymbol(From);
879   MCSymbol *ToSym = getContext().getOrCreateSymbol(To);
880 
881   getStreamer().emitCGProfileEntry(
882       MCSymbolRefExpr::create(FromSym, MCSymbolRefExpr::VK_None, getContext(),
883                               FromLoc),
884       MCSymbolRefExpr::create(ToSym, MCSymbolRefExpr::VK_None, getContext(),
885                               ToLoc),
886       Count);
887   return false;
888 }
889 
890 namespace llvm {
891 
892 MCAsmParserExtension *createELFAsmParser() {
893   return new ELFAsmParser;
894 }
895 
896 } // end namespace llvm
897