xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCParser/ELFAsmParser.cpp (revision e9e8876a4d6afc1ad5315faaa191b25121a813d7) 
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/StringRef.h"
10 #include "llvm/ADT/StringSwitch.h"
11 #include "llvm/BinaryFormat/ELF.h"
12 #include "llvm/MC/MCAsmInfo.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCDirectives.h"
15 #include "llvm/MC/MCExpr.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/MCSection.h"
20 #include "llvm/MC/MCSectionELF.h"
21 #include "llvm/MC/MCStreamer.h"
22 #include "llvm/MC/MCSymbol.h"
23 #include "llvm/MC/MCSymbolELF.h"
24 #include "llvm/MC/SectionKind.h"
25 #include "llvm/Support/Casting.h"
26 #include "llvm/Support/MathExtras.h"
27 #include "llvm/Support/SMLoc.h"
28 #include <cassert>
29 #include <cstdint>
30 #include <utility>
31 
32 using namespace llvm;
33 
34 namespace {
35 
36 class ELFAsmParser : public MCAsmParserExtension {
37   template<bool (ELFAsmParser::*HandlerMethod)(StringRef, SMLoc)>
38   void addDirectiveHandler(StringRef Directive) {
39     MCAsmParser::ExtensionDirectiveHandler Handler = std::make_pair(
40         this, HandleDirective<ELFAsmParser, HandlerMethod>);
41 
42     getParser().addDirectiveHandler(Directive, Handler);
43   }
44 
45   bool ParseSectionSwitch(StringRef Section, unsigned Type, unsigned Flags,
46                           SectionKind Kind);
47 
48 public:
49   ELFAsmParser() { BracketExpressionsSupported = true; }
50 
51   void Initialize(MCAsmParser &Parser) override {
52     // Call the base implementation.
53     this->MCAsmParserExtension::Initialize(Parser);
54 
55     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveData>(".data");
56     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveText>(".text");
57     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveBSS>(".bss");
58     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveRoData>(".rodata");
59     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTData>(".tdata");
60     addDirectiveHandler<&ELFAsmParser::ParseSectionDirectiveTBSS>(".tbss");
61     addDirectiveHandler<
62       &ELFAsmParser::ParseSectionDirectiveDataRel>(".data.rel");
63     addDirectiveHandler<
64       &ELFAsmParser::ParseSectionDirectiveDataRelRo>(".data.rel.ro");
65     addDirectiveHandler<
66       &ELFAsmParser::ParseSectionDirectiveEhFrame>(".eh_frame");
67     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSection>(".section");
68     addDirectiveHandler<
69       &ELFAsmParser::ParseDirectivePushSection>(".pushsection");
70     addDirectiveHandler<&ELFAsmParser::ParseDirectivePopSection>(".popsection");
71     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSize>(".size");
72     addDirectiveHandler<&ELFAsmParser::ParseDirectivePrevious>(".previous");
73     addDirectiveHandler<&ELFAsmParser::ParseDirectiveType>(".type");
74     addDirectiveHandler<&ELFAsmParser::ParseDirectiveIdent>(".ident");
75     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymver>(".symver");
76     addDirectiveHandler<&ELFAsmParser::ParseDirectiveVersion>(".version");
77     addDirectiveHandler<&ELFAsmParser::ParseDirectiveWeakref>(".weakref");
78     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".weak");
79     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSymbolAttribute>(".local");
80     addDirectiveHandler<
81       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".protected");
82     addDirectiveHandler<
83       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".internal");
84     addDirectiveHandler<
85       &ELFAsmParser::ParseDirectiveSymbolAttribute>(".hidden");
86     addDirectiveHandler<&ELFAsmParser::ParseDirectiveSubsection>(".subsection");
87     addDirectiveHandler<&ELFAsmParser::ParseDirectiveCGProfile>(".cg_profile");
88   }
89 
90   // FIXME: Part of this logic is duplicated in the MCELFStreamer. What is
91   // the best way for us to get access to it?
92   bool ParseSectionDirectiveData(StringRef, SMLoc) {
93     return ParseSectionSwitch(".data", ELF::SHT_PROGBITS,
94                               ELF::SHF_WRITE | ELF::SHF_ALLOC,
95                               SectionKind::getData());
96   }
97   bool ParseSectionDirectiveText(StringRef, SMLoc) {
98     return ParseSectionSwitch(".text", ELF::SHT_PROGBITS,
99                               ELF::SHF_EXECINSTR |
100                               ELF::SHF_ALLOC, SectionKind::getText());
101   }
102   bool ParseSectionDirectiveBSS(StringRef, SMLoc) {
103     return ParseSectionSwitch(".bss", ELF::SHT_NOBITS,
104                               ELF::SHF_WRITE |
105                               ELF::SHF_ALLOC, SectionKind::getBSS());
106   }
107   bool ParseSectionDirectiveRoData(StringRef, SMLoc) {
108     return ParseSectionSwitch(".rodata", ELF::SHT_PROGBITS,
109                               ELF::SHF_ALLOC,
110                               SectionKind::getReadOnly());
111   }
112   bool ParseSectionDirectiveTData(StringRef, SMLoc) {
113     return ParseSectionSwitch(".tdata", ELF::SHT_PROGBITS,
114                               ELF::SHF_ALLOC |
115                               ELF::SHF_TLS | ELF::SHF_WRITE,
116                               SectionKind::getThreadData());
117   }
118   bool ParseSectionDirectiveTBSS(StringRef, SMLoc) {
119     return ParseSectionSwitch(".tbss", ELF::SHT_NOBITS,
120                               ELF::SHF_ALLOC |
121                               ELF::SHF_TLS | ELF::SHF_WRITE,
122                               SectionKind::getThreadBSS());
123   }
124   bool ParseSectionDirectiveDataRel(StringRef, SMLoc) {
125     return ParseSectionSwitch(".data.rel", ELF::SHT_PROGBITS,
126                               ELF::SHF_ALLOC | ELF::SHF_WRITE,
127                               SectionKind::getData());
128   }
129   bool ParseSectionDirectiveDataRelRo(StringRef, SMLoc) {
130     return ParseSectionSwitch(".data.rel.ro", ELF::SHT_PROGBITS,
131                               ELF::SHF_ALLOC |
132                               ELF::SHF_WRITE,
133                               SectionKind::getReadOnlyWithRel());
134   }
135   bool ParseSectionDirectiveEhFrame(StringRef, SMLoc) {
136     return ParseSectionSwitch(".eh_frame", ELF::SHT_PROGBITS,
137                               ELF::SHF_ALLOC | ELF::SHF_WRITE,
138                               SectionKind::getData());
139   }
140   bool ParseDirectivePushSection(StringRef, SMLoc);
141   bool ParseDirectivePopSection(StringRef, SMLoc);
142   bool ParseDirectiveSection(StringRef, SMLoc);
143   bool ParseDirectiveSize(StringRef, SMLoc);
144   bool ParseDirectivePrevious(StringRef, SMLoc);
145   bool ParseDirectiveType(StringRef, SMLoc);
146   bool ParseDirectiveIdent(StringRef, SMLoc);
147   bool ParseDirectiveSymver(StringRef, SMLoc);
148   bool ParseDirectiveVersion(StringRef, SMLoc);
149   bool ParseDirectiveWeakref(StringRef, SMLoc);
150   bool ParseDirectiveSymbolAttribute(StringRef, SMLoc);
151   bool ParseDirectiveSubsection(StringRef, SMLoc);
152   bool ParseDirectiveCGProfile(StringRef, SMLoc);
153 
154 private:
155   bool ParseSectionName(StringRef &SectionName);
156   bool ParseSectionArguments(bool IsPush, SMLoc loc);
157   unsigned parseSunStyleSectionFlags();
158   bool maybeParseSectionType(StringRef &TypeName);
159   bool parseMergeSize(int64_t &Size);
160   bool parseGroup(StringRef &GroupName, bool &IsComdat);
161   bool parseLinkedToSym(MCSymbolELF *&LinkedToSym);
162   bool maybeParseUniqueID(int64_t &UniqueID);
163 };
164 
165 } // end anonymous namespace
166 
167 /// ParseDirectiveSymbolAttribute
168 ///  ::= { ".local", ".weak", ... } [ identifier ( , identifier )* ]
169 bool ELFAsmParser::ParseDirectiveSymbolAttribute(StringRef Directive, SMLoc) {
170   MCSymbolAttr Attr = StringSwitch<MCSymbolAttr>(Directive)
171     .Case(".weak", MCSA_Weak)
172     .Case(".local", MCSA_Local)
173     .Case(".hidden", MCSA_Hidden)
174     .Case(".internal", MCSA_Internal)
175     .Case(".protected", MCSA_Protected)
176     .Default(MCSA_Invalid);
177   assert(Attr != MCSA_Invalid && "unexpected symbol attribute directive!");
178   if (getLexer().isNot(AsmToken::EndOfStatement)) {
179     while (true) {
180       StringRef Name;
181 
182       if (getParser().parseIdentifier(Name))
183         return TokError("expected identifier in directive");
184 
185       if (getParser().discardLTOSymbol(Name)) {
186         if (getLexer().is(AsmToken::EndOfStatement))
187           break;
188         continue;
189       }
190 
191       MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
192 
193       getStreamer().emitSymbolAttribute(Sym, Attr);
194 
195       if (getLexer().is(AsmToken::EndOfStatement))
196         break;
197 
198       if (getLexer().isNot(AsmToken::Comma))
199         return TokError("unexpected token in directive");
200       Lex();
201     }
202   }
203 
204   Lex();
205   return false;
206 }
207 
208 bool ELFAsmParser::ParseSectionSwitch(StringRef Section, unsigned Type,
209                                       unsigned Flags, SectionKind Kind) {
210   const MCExpr *Subsection = nullptr;
211   if (getLexer().isNot(AsmToken::EndOfStatement)) {
212     if (getParser().parseExpression(Subsection))
213       return true;
214   }
215   Lex();
216 
217   getStreamer().SwitchSection(getContext().getELFSection(Section, Type, Flags),
218                               Subsection);
219 
220   return false;
221 }
222 
223 bool ELFAsmParser::ParseDirectiveSize(StringRef, SMLoc) {
224   StringRef Name;
225   if (getParser().parseIdentifier(Name))
226     return TokError("expected identifier in directive");
227   MCSymbolELF *Sym = cast<MCSymbolELF>(getContext().getOrCreateSymbol(Name));
228 
229   if (getLexer().isNot(AsmToken::Comma))
230     return TokError("unexpected token in directive");
231   Lex();
232 
233   const MCExpr *Expr;
234   if (getParser().parseExpression(Expr))
235     return true;
236 
237   if (getLexer().isNot(AsmToken::EndOfStatement))
238     return TokError("unexpected token in directive");
239   Lex();
240 
241   getStreamer().emitELFSize(Sym, Expr);
242   return false;
243 }
244 
245 bool ELFAsmParser::ParseSectionName(StringRef &SectionName) {
246   // A section name can contain -, so we cannot just use
247   // parseIdentifier.
248   SMLoc FirstLoc = getLexer().getLoc();
249   unsigned Size = 0;
250 
251   if (getLexer().is(AsmToken::String)) {
252     SectionName = getTok().getIdentifier();
253     Lex();
254     return false;
255   }
256 
257   while (!getParser().hasPendingError()) {
258     SMLoc PrevLoc = getLexer().getLoc();
259     if (getLexer().is(AsmToken::Comma) ||
260       getLexer().is(AsmToken::EndOfStatement))
261       break;
262 
263     unsigned CurSize;
264     if (getLexer().is(AsmToken::String)) {
265       CurSize = getTok().getIdentifier().size() + 2;
266       Lex();
267     } else if (getLexer().is(AsmToken::Identifier)) {
268       CurSize = getTok().getIdentifier().size();
269       Lex();
270     } else {
271       CurSize = getTok().getString().size();
272       Lex();
273     }
274     Size += CurSize;
275     SectionName = StringRef(FirstLoc.getPointer(), Size);
276 
277     // Make sure the following token is adjacent.
278     if (PrevLoc.getPointer() + CurSize != getTok().getLoc().getPointer())
279       break;
280   }
281   if (Size == 0)
282     return true;
283 
284   return false;
285 }
286 
287 static unsigned parseSectionFlags(StringRef flagsStr, 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       flags |= ELF::XCORE_SHF_CP_SECTION;
322       break;
323     case 'd':
324       flags |= ELF::XCORE_SHF_DP_SECTION;
325       break;
326     case 'y':
327       flags |= ELF::SHF_ARM_PURECODE;
328       break;
329     case 's':
330       flags |= ELF::SHF_HEX_GPREL;
331       break;
332     case 'G':
333       flags |= ELF::SHF_GROUP;
334       break;
335     case 'R':
336       flags |= ELF::SHF_GNU_RETAIN;
337       break;
338     case '?':
339       *UseLastGroup = true;
340       break;
341     default:
342       return -1U;
343     }
344   }
345 
346   return flags;
347 }
348 
349 unsigned ELFAsmParser::parseSunStyleSectionFlags() {
350   unsigned flags = 0;
351   while (getLexer().is(AsmToken::Hash)) {
352     Lex(); // Eat the #.
353 
354     if (!getLexer().is(AsmToken::Identifier))
355       return -1U;
356 
357     StringRef flagId = getTok().getIdentifier();
358     if (flagId == "alloc")
359       flags |= ELF::SHF_ALLOC;
360     else if (flagId == "execinstr")
361       flags |= ELF::SHF_EXECINSTR;
362     else if (flagId == "write")
363       flags |= ELF::SHF_WRITE;
364     else if (flagId == "tls")
365       flags |= ELF::SHF_TLS;
366     else
367       return -1U;
368 
369     Lex(); // Eat the flag.
370 
371     if (!getLexer().is(AsmToken::Comma))
372         break;
373     Lex(); // Eat the comma.
374   }
375   return flags;
376 }
377 
378 
379 bool ELFAsmParser::ParseDirectivePushSection(StringRef s, SMLoc loc) {
380   getStreamer().PushSection();
381 
382   if (ParseSectionArguments(/*IsPush=*/true, loc)) {
383     getStreamer().PopSection();
384     return true;
385   }
386 
387   return false;
388 }
389 
390 bool ELFAsmParser::ParseDirectivePopSection(StringRef, SMLoc) {
391   if (!getStreamer().PopSection())
392     return TokError(".popsection without corresponding .pushsection");
393   return false;
394 }
395 
396 bool ELFAsmParser::ParseDirectiveSection(StringRef, SMLoc loc) {
397   return ParseSectionArguments(/*IsPush=*/false, loc);
398 }
399 
400 bool ELFAsmParser::maybeParseSectionType(StringRef &TypeName) {
401   MCAsmLexer &L = getLexer();
402   if (L.isNot(AsmToken::Comma))
403     return false;
404   Lex();
405   if (L.isNot(AsmToken::At) && L.isNot(AsmToken::Percent) &&
406       L.isNot(AsmToken::String)) {
407     if (L.getAllowAtInIdentifier())
408       return TokError("expected '@<type>', '%<type>' or \"<type>\"");
409     else
410       return TokError("expected '%<type>' or \"<type>\"");
411   }
412   if (!L.is(AsmToken::String))
413     Lex();
414   if (L.is(AsmToken::Integer)) {
415     TypeName = getTok().getString();
416     Lex();
417   } else if (getParser().parseIdentifier(TypeName))
418     return TokError("expected identifier in directive");
419   return false;
420 }
421 
422 bool ELFAsmParser::parseMergeSize(int64_t &Size) {
423   if (getLexer().isNot(AsmToken::Comma))
424     return TokError("expected the entry size");
425   Lex();
426   if (getParser().parseAbsoluteExpression(Size))
427     return true;
428   if (Size <= 0)
429     return TokError("entry size must be positive");
430   return false;
431 }
432 
433 bool ELFAsmParser::parseGroup(StringRef &GroupName, bool &IsComdat) {
434   MCAsmLexer &L = getLexer();
435   if (L.isNot(AsmToken::Comma))
436     return TokError("expected group name");
437   Lex();
438   if (L.is(AsmToken::Integer)) {
439     GroupName = getTok().getString();
440     Lex();
441   } else if (getParser().parseIdentifier(GroupName)) {
442     return TokError("invalid group name");
443   }
444   if (L.is(AsmToken::Comma)) {
445     Lex();
446     StringRef Linkage;
447     if (getParser().parseIdentifier(Linkage))
448       return TokError("invalid linkage");
449     if (Linkage != "comdat")
450       return TokError("Linkage must be 'comdat'");
451     IsComdat = true;
452   } else {
453     IsComdat = false;
454   }
455   return false;
456 }
457 
458 bool ELFAsmParser::parseLinkedToSym(MCSymbolELF *&LinkedToSym) {
459   MCAsmLexer &L = getLexer();
460   if (L.isNot(AsmToken::Comma))
461     return TokError("expected linked-to symbol");
462   Lex();
463   StringRef Name;
464   SMLoc StartLoc = L.getLoc();
465   if (getParser().parseIdentifier(Name)) {
466     if (getParser().getTok().getString() == "0") {
467       getParser().Lex();
468       LinkedToSym = nullptr;
469       return false;
470     }
471     return TokError("invalid linked-to symbol");
472   }
473   LinkedToSym = dyn_cast_or_null<MCSymbolELF>(getContext().lookupSymbol(Name));
474   if (!LinkedToSym || !LinkedToSym->isInSection())
475     return Error(StartLoc, "linked-to symbol is not in a section: " + Name);
476   return false;
477 }
478 
479 bool ELFAsmParser::maybeParseUniqueID(int64_t &UniqueID) {
480   MCAsmLexer &L = getLexer();
481   if (L.isNot(AsmToken::Comma))
482     return false;
483   Lex();
484   StringRef UniqueStr;
485   if (getParser().parseIdentifier(UniqueStr))
486     return TokError("expected identifier in directive");
487   if (UniqueStr != "unique")
488     return TokError("expected 'unique'");
489   if (L.isNot(AsmToken::Comma))
490     return TokError("expected commma");
491   Lex();
492   if (getParser().parseAbsoluteExpression(UniqueID))
493     return true;
494   if (UniqueID < 0)
495     return TokError("unique id must be positive");
496   if (!isUInt<32>(UniqueID) || UniqueID == ~0U)
497     return TokError("unique id is too large");
498   return false;
499 }
500 
501 static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
502   return SectionName.startswith(Prefix) || SectionName == Prefix.drop_back();
503 }
504 
505 bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
506   StringRef SectionName;
507 
508   if (ParseSectionName(SectionName))
509     return TokError("expected identifier in directive");
510 
511   StringRef TypeName;
512   int64_t Size = 0;
513   StringRef GroupName;
514   bool IsComdat = false;
515   unsigned Flags = 0;
516   unsigned extraFlags = 0;
517   const MCExpr *Subsection = nullptr;
518   bool UseLastGroup = false;
519   MCSymbolELF *LinkedToSym = nullptr;
520   int64_t UniqueID = ~0;
521 
522   // Set the defaults first.
523   if (hasPrefix(SectionName, ".rodata.") || SectionName == ".rodata1")
524     Flags |= ELF::SHF_ALLOC;
525   else if (SectionName == ".fini" || SectionName == ".init" ||
526            hasPrefix(SectionName, ".text."))
527     Flags |= ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
528   else if (hasPrefix(SectionName, ".data.") || SectionName == ".data1" ||
529            hasPrefix(SectionName, ".bss.") ||
530            hasPrefix(SectionName, ".init_array.") ||
531            hasPrefix(SectionName, ".fini_array.") ||
532            hasPrefix(SectionName, ".preinit_array."))
533     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE;
534   else if (hasPrefix(SectionName, ".tdata.") ||
535            hasPrefix(SectionName, ".tbss."))
536     Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_TLS;
537 
538   if (getLexer().is(AsmToken::Comma)) {
539     Lex();
540 
541     if (IsPush && getLexer().isNot(AsmToken::String)) {
542       if (getParser().parseExpression(Subsection))
543         return true;
544       if (getLexer().isNot(AsmToken::Comma))
545         goto EndStmt;
546       Lex();
547     }
548 
549     if (getLexer().isNot(AsmToken::String)) {
550       if (!getContext().getAsmInfo()->usesSunStyleELFSectionSwitchSyntax()
551           || getLexer().isNot(AsmToken::Hash))
552         return TokError("expected string in directive");
553       extraFlags = parseSunStyleSectionFlags();
554     } else {
555       StringRef FlagsStr = getTok().getStringContents();
556       Lex();
557       extraFlags = parseSectionFlags(FlagsStr, &UseLastGroup);
558     }
559 
560     if (extraFlags == -1U)
561       return TokError("unknown flag");
562     Flags |= extraFlags;
563 
564     bool Mergeable = Flags & ELF::SHF_MERGE;
565     bool Group = Flags & ELF::SHF_GROUP;
566     if (Group && UseLastGroup)
567       return TokError("Section cannot specifiy a group name while also acting "
568                       "as a member of the last group");
569 
570     if (maybeParseSectionType(TypeName))
571       return true;
572 
573     MCAsmLexer &L = getLexer();
574     if (TypeName.empty()) {
575       if (Mergeable)
576         return TokError("Mergeable section must specify the type");
577       if (Group)
578         return TokError("Group section must specify the type");
579       if (L.isNot(AsmToken::EndOfStatement))
580         return TokError("unexpected token in directive");
581     }
582 
583     if (Mergeable)
584       if (parseMergeSize(Size))
585         return true;
586     if (Group)
587       if (parseGroup(GroupName, IsComdat))
588         return true;
589     if (Flags & ELF::SHF_LINK_ORDER)
590       if (parseLinkedToSym(LinkedToSym))
591         return true;
592     if (maybeParseUniqueID(UniqueID))
593       return true;
594   }
595 
596 EndStmt:
597   if (getLexer().isNot(AsmToken::EndOfStatement))
598     return TokError("unexpected token in directive");
599   Lex();
600 
601   unsigned Type = ELF::SHT_PROGBITS;
602 
603   if (TypeName.empty()) {
604     if (SectionName.startswith(".note"))
605       Type = ELF::SHT_NOTE;
606     else if (hasPrefix(SectionName, ".init_array."))
607       Type = ELF::SHT_INIT_ARRAY;
608     else if (hasPrefix(SectionName, ".bss."))
609       Type = ELF::SHT_NOBITS;
610     else if (hasPrefix(SectionName, ".tbss."))
611       Type = ELF::SHT_NOBITS;
612     else if (hasPrefix(SectionName, ".fini_array."))
613       Type = ELF::SHT_FINI_ARRAY;
614     else if (hasPrefix(SectionName, ".preinit_array."))
615       Type = ELF::SHT_PREINIT_ARRAY;
616   } else {
617     if (TypeName == "init_array")
618       Type = ELF::SHT_INIT_ARRAY;
619     else if (TypeName == "fini_array")
620       Type = ELF::SHT_FINI_ARRAY;
621     else if (TypeName == "preinit_array")
622       Type = ELF::SHT_PREINIT_ARRAY;
623     else if (TypeName == "nobits")
624       Type = ELF::SHT_NOBITS;
625     else if (TypeName == "progbits")
626       Type = ELF::SHT_PROGBITS;
627     else if (TypeName == "note")
628       Type = ELF::SHT_NOTE;
629     else if (TypeName == "unwind")
630       Type = ELF::SHT_X86_64_UNWIND;
631     else if (TypeName == "llvm_odrtab")
632       Type = ELF::SHT_LLVM_ODRTAB;
633     else if (TypeName == "llvm_linker_options")
634       Type = ELF::SHT_LLVM_LINKER_OPTIONS;
635     else if (TypeName == "llvm_call_graph_profile")
636       Type = ELF::SHT_LLVM_CALL_GRAPH_PROFILE;
637     else if (TypeName == "llvm_dependent_libraries")
638       Type = ELF::SHT_LLVM_DEPENDENT_LIBRARIES;
639     else if (TypeName == "llvm_sympart")
640       Type = ELF::SHT_LLVM_SYMPART;
641     else if (TypeName == "llvm_bb_addr_map")
642       Type = ELF::SHT_LLVM_BB_ADDR_MAP;
643     else if (TypeName.getAsInteger(0, Type))
644       return TokError("unknown section type");
645   }
646 
647   if (UseLastGroup) {
648     MCSectionSubPair CurrentSection = getStreamer().getCurrentSection();
649     if (const MCSectionELF *Section =
650             cast_or_null<MCSectionELF>(CurrentSection.first))
651       if (const MCSymbol *Group = Section->getGroup()) {
652         GroupName = Group->getName();
653         IsComdat = Section->isComdat();
654         Flags |= ELF::SHF_GROUP;
655       }
656   }
657 
658   MCSectionELF *Section =
659       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
660                                  IsComdat, UniqueID, LinkedToSym);
661   getStreamer().SwitchSection(Section, Subsection);
662   // x86-64 psABI names SHT_X86_64_UNWIND as the canonical type for .eh_frame,
663   // but GNU as emits SHT_PROGBITS .eh_frame for .cfi_* directives. Don't error
664   // for SHT_PROGBITS .eh_frame
665   if (Section->getType() != Type &&
666       !(SectionName == ".eh_frame" && Type == ELF::SHT_PROGBITS))
667     Error(loc, "changed section type for " + SectionName + ", expected: 0x" +
668                    utohexstr(Section->getType()));
669   // Check that flags are used consistently. However, the GNU assembler permits
670   // to leave out in subsequent uses of the same sections; for compatibility,
671   // do likewise.
672   if ((extraFlags || Size || !TypeName.empty()) && Section->getFlags() != Flags)
673     Error(loc, "changed section flags for " + SectionName + ", expected: 0x" +
674                    utohexstr(Section->getFlags()));
675   if ((extraFlags || Size || !TypeName.empty()) &&
676       Section->getEntrySize() != Size)
677     Error(loc, "changed section entsize for " + SectionName +
678                    ", expected: " + Twine(Section->getEntrySize()));
679 
680   if (getContext().getGenDwarfForAssembly() &&
681       (Section->getFlags() & ELF::SHF_ALLOC) &&
682       (Section->getFlags() & ELF::SHF_EXECINSTR)) {
683     bool InsertResult = getContext().addGenDwarfSection(Section);
684     if (InsertResult) {
685       if (getContext().getDwarfVersion() <= 2)
686         Warning(loc, "DWARF2 only supports one section per compilation unit");
687 
688       if (!Section->getBeginSymbol()) {
689         MCSymbol *SectionStartSymbol = getContext().createTempSymbol();
690         getStreamer().emitLabel(SectionStartSymbol);
691         Section->setBeginSymbol(SectionStartSymbol);
692       }
693     }
694   }
695 
696   return false;
697 }
698 
699 bool ELFAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
700   MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
701   if (PreviousSection.first == nullptr)
702       return TokError(".previous without corresponding .section");
703   getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
704 
705   return false;
706 }
707 
708 static MCSymbolAttr MCAttrForString(StringRef Type) {
709   return StringSwitch<MCSymbolAttr>(Type)
710           .Cases("STT_FUNC", "function", MCSA_ELF_TypeFunction)
711           .Cases("STT_OBJECT", "object", MCSA_ELF_TypeObject)
712           .Cases("STT_TLS", "tls_object", MCSA_ELF_TypeTLS)
713           .Cases("STT_COMMON", "common", MCSA_ELF_TypeCommon)
714           .Cases("STT_NOTYPE", "notype", MCSA_ELF_TypeNoType)
715           .Cases("STT_GNU_IFUNC", "gnu_indirect_function",
716                  MCSA_ELF_TypeIndFunction)
717           .Case("gnu_unique_object", MCSA_ELF_TypeGnuUniqueObject)
718           .Default(MCSA_Invalid);
719 }
720 
721 /// ParseDirectiveELFType
722 ///  ::= .type identifier , STT_<TYPE_IN_UPPER_CASE>
723 ///  ::= .type identifier , #attribute
724 ///  ::= .type identifier , @attribute
725 ///  ::= .type identifier , %attribute
726 ///  ::= .type identifier , "attribute"
727 bool ELFAsmParser::ParseDirectiveType(StringRef, SMLoc) {
728   StringRef Name;
729   if (getParser().parseIdentifier(Name))
730     return TokError("expected identifier in directive");
731 
732   // Handle the identifier as the key symbol.
733   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
734 
735   // NOTE the comma is optional in all cases.  It is only documented as being
736   // optional in the first case, however, GAS will silently treat the comma as
737   // optional in all cases.  Furthermore, although the documentation states that
738   // the first form only accepts STT_<TYPE_IN_UPPER_CASE>, in reality, GAS
739   // accepts both the upper case name as well as the lower case aliases.
740   if (getLexer().is(AsmToken::Comma))
741     Lex();
742 
743   if (getLexer().isNot(AsmToken::Identifier) &&
744       getLexer().isNot(AsmToken::Hash) &&
745       getLexer().isNot(AsmToken::Percent) &&
746       getLexer().isNot(AsmToken::String)) {
747     if (!getLexer().getAllowAtInIdentifier())
748       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', "
749                       "'%<type>' or \"<type>\"");
750     else if (getLexer().isNot(AsmToken::At))
751       return TokError("expected STT_<TYPE_IN_UPPER_CASE>, '#<type>', '@<type>', "
752                       "'%<type>' or \"<type>\"");
753   }
754 
755   if (getLexer().isNot(AsmToken::String) &&
756       getLexer().isNot(AsmToken::Identifier))
757     Lex();
758 
759   SMLoc TypeLoc = getLexer().getLoc();
760 
761   StringRef Type;
762   if (getParser().parseIdentifier(Type))
763     return TokError("expected symbol type in directive");
764 
765   MCSymbolAttr Attr = MCAttrForString(Type);
766   if (Attr == MCSA_Invalid)
767     return Error(TypeLoc, "unsupported attribute in '.type' directive");
768 
769   if (getLexer().isNot(AsmToken::EndOfStatement))
770     return TokError("unexpected token in '.type' directive");
771   Lex();
772 
773   getStreamer().emitSymbolAttribute(Sym, Attr);
774 
775   return false;
776 }
777 
778 /// ParseDirectiveIdent
779 ///  ::= .ident string
780 bool ELFAsmParser::ParseDirectiveIdent(StringRef, SMLoc) {
781   if (getLexer().isNot(AsmToken::String))
782     return TokError("unexpected token in '.ident' directive");
783 
784   StringRef Data = getTok().getIdentifier();
785 
786   Lex();
787 
788   if (getLexer().isNot(AsmToken::EndOfStatement))
789     return TokError("unexpected token in '.ident' directive");
790   Lex();
791 
792   getStreamer().emitIdent(Data);
793   return false;
794 }
795 
796 /// ParseDirectiveSymver
797 ///  ::= .symver foo, bar2@zed
798 bool ELFAsmParser::ParseDirectiveSymver(StringRef, SMLoc) {
799   StringRef OriginalName, Name, Action;
800   if (getParser().parseIdentifier(OriginalName))
801     return TokError("expected identifier in directive");
802 
803   if (getLexer().isNot(AsmToken::Comma))
804     return TokError("expected a comma");
805 
806   // ARM assembly uses @ for a comment...
807   // except when parsing the second parameter of the .symver directive.
808   // Force the next symbol to allow @ in the identifier, which is
809   // required for this directive and then reset it to its initial state.
810   const bool AllowAtInIdentifier = getLexer().getAllowAtInIdentifier();
811   getLexer().setAllowAtInIdentifier(true);
812   Lex();
813   getLexer().setAllowAtInIdentifier(AllowAtInIdentifier);
814 
815   if (getParser().parseIdentifier(Name))
816     return TokError("expected identifier in directive");
817 
818   if (Name.find('@') == StringRef::npos)
819     return TokError("expected a '@' in the name");
820   bool KeepOriginalSym = !Name.contains("@@@");
821   if (parseOptionalToken(AsmToken::Comma)) {
822     if (getParser().parseIdentifier(Action) || Action != "remove")
823       return TokError("expected 'remove'");
824     KeepOriginalSym = false;
825   }
826   (void)parseOptionalToken(AsmToken::EndOfStatement);
827 
828   getStreamer().emitELFSymverDirective(
829       getContext().getOrCreateSymbol(OriginalName), Name, KeepOriginalSym);
830   return false;
831 }
832 
833 /// ParseDirectiveVersion
834 ///  ::= .version string
835 bool ELFAsmParser::ParseDirectiveVersion(StringRef, SMLoc) {
836   if (getLexer().isNot(AsmToken::String))
837     return TokError("unexpected token in '.version' directive");
838 
839   StringRef Data = getTok().getIdentifier();
840 
841   Lex();
842 
843   MCSection *Note = getContext().getELFSection(".note", ELF::SHT_NOTE, 0);
844 
845   getStreamer().PushSection();
846   getStreamer().SwitchSection(Note);
847   getStreamer().emitInt32(Data.size() + 1); // namesz
848   getStreamer().emitInt32(0);               // descsz = 0 (no description).
849   getStreamer().emitInt32(1);               // type = NT_VERSION
850   getStreamer().emitBytes(Data);            // name
851   getStreamer().emitInt8(0);                // NUL
852   getStreamer().emitValueToAlignment(4);
853   getStreamer().PopSection();
854   return false;
855 }
856 
857 /// ParseDirectiveWeakref
858 ///  ::= .weakref foo, bar
859 bool ELFAsmParser::ParseDirectiveWeakref(StringRef, SMLoc) {
860   // FIXME: Share code with the other alias building directives.
861 
862   StringRef AliasName;
863   if (getParser().parseIdentifier(AliasName))
864     return TokError("expected identifier in directive");
865 
866   if (getLexer().isNot(AsmToken::Comma))
867     return TokError("expected a comma");
868 
869   Lex();
870 
871   StringRef Name;
872   if (getParser().parseIdentifier(Name))
873     return TokError("expected identifier in directive");
874 
875   MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
876 
877   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
878 
879   getStreamer().emitWeakReference(Alias, Sym);
880   return false;
881 }
882 
883 bool ELFAsmParser::ParseDirectiveSubsection(StringRef, SMLoc) {
884   const MCExpr *Subsection = nullptr;
885   if (getLexer().isNot(AsmToken::EndOfStatement)) {
886     if (getParser().parseExpression(Subsection))
887      return true;
888   }
889 
890   if (getLexer().isNot(AsmToken::EndOfStatement))
891     return TokError("unexpected token in directive");
892 
893   Lex();
894 
895   getStreamer().SubSection(Subsection);
896   return false;
897 }
898 
899 bool ELFAsmParser::ParseDirectiveCGProfile(StringRef S, SMLoc Loc) {
900   return MCAsmParserExtension::ParseDirectiveCGProfile(S, Loc);
901 }
902 
903 namespace llvm {
904 
905 MCAsmParserExtension *createELFAsmParser() {
906   return new ELFAsmParser;
907 }
908 
909 } // end namespace llvm
910