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[llvm/stm8.git] / lib / MC / ELFObjectWriter.cpp
blobb7d30cd46bf77dbf64955f4304eef18ecaeb9d95
1 //===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===//
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 // This file implements ELF object file writer information.
12 //===----------------------------------------------------------------------===//
14 #include "ELFObjectWriter.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/StringMap.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/MC/MCAsmLayout.h"
19 #include "llvm/MC/MCContext.h"
20 #include "llvm/MC/MCExpr.h"
21 #include "llvm/MC/MCSectionELF.h"
22 #include "llvm/MC/MCValue.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/ELF.h"
26 #include "llvm/Target/TargetAsmBackend.h"
27 #include "llvm/ADT/StringSwitch.h"
29 #include "../Target/X86/X86FixupKinds.h"
30 #include "../Target/ARM/ARMFixupKinds.h"
32 #include <vector>
33 using namespace llvm;
35 bool ELFObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
36 const MCFixupKindInfo &FKI =
37 Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind);
39 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
42 bool ELFObjectWriter::RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
43 switch (Variant) {
44 default:
45 return false;
46 case MCSymbolRefExpr::VK_GOT:
47 case MCSymbolRefExpr::VK_PLT:
48 case MCSymbolRefExpr::VK_GOTPCREL:
49 case MCSymbolRefExpr::VK_TPOFF:
50 case MCSymbolRefExpr::VK_TLSGD:
51 case MCSymbolRefExpr::VK_GOTTPOFF:
52 case MCSymbolRefExpr::VK_INDNTPOFF:
53 case MCSymbolRefExpr::VK_NTPOFF:
54 case MCSymbolRefExpr::VK_GOTNTPOFF:
55 case MCSymbolRefExpr::VK_TLSLDM:
56 case MCSymbolRefExpr::VK_DTPOFF:
57 case MCSymbolRefExpr::VK_TLSLD:
58 return true;
62 ELFObjectWriter::~ELFObjectWriter()
65 // Emit the ELF header.
66 void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize,
67 unsigned NumberOfSections) {
68 // ELF Header
69 // ----------
71 // Note
72 // ----
73 // emitWord method behaves differently for ELF32 and ELF64, writing
74 // 4 bytes in the former and 8 in the latter.
76 Write8(0x7f); // e_ident[EI_MAG0]
77 Write8('E'); // e_ident[EI_MAG1]
78 Write8('L'); // e_ident[EI_MAG2]
79 Write8('F'); // e_ident[EI_MAG3]
81 Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
83 // e_ident[EI_DATA]
84 Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
86 Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
87 // e_ident[EI_OSABI]
88 switch (TargetObjectWriter->getOSType()) {
89 case Triple::FreeBSD: Write8(ELF::ELFOSABI_FREEBSD); break;
90 case Triple::Linux: Write8(ELF::ELFOSABI_LINUX); break;
91 default: Write8(ELF::ELFOSABI_NONE); break;
93 Write8(0); // e_ident[EI_ABIVERSION]
95 WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
97 Write16(ELF::ET_REL); // e_type
99 Write16(TargetObjectWriter->getEMachine()); // e_machine = target
101 Write32(ELF::EV_CURRENT); // e_version
102 WriteWord(0); // e_entry, no entry point in .o file
103 WriteWord(0); // e_phoff, no program header for .o
104 WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
105 sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes
107 // e_flags = whatever the target wants
108 WriteEFlags();
110 // e_ehsize = ELF header size
111 Write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
113 Write16(0); // e_phentsize = prog header entry size
114 Write16(0); // e_phnum = # prog header entries = 0
116 // e_shentsize = Section header entry size
117 Write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
119 // e_shnum = # of section header ents
120 if (NumberOfSections >= ELF::SHN_LORESERVE)
121 Write16(0);
122 else
123 Write16(NumberOfSections);
125 // e_shstrndx = Section # of '.shstrtab'
126 if (NumberOfSections >= ELF::SHN_LORESERVE)
127 Write16(ELF::SHN_XINDEX);
128 else
129 Write16(ShstrtabIndex);
132 void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
133 MCDataFragment *ShndxF,
134 uint64_t name,
135 uint8_t info, uint64_t value,
136 uint64_t size, uint8_t other,
137 uint32_t shndx,
138 bool Reserved) {
139 if (ShndxF) {
140 if (shndx >= ELF::SHN_LORESERVE && !Reserved)
141 String32(*ShndxF, shndx);
142 else
143 String32(*ShndxF, 0);
146 uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
147 uint16_t(ELF::SHN_XINDEX) : shndx;
149 if (is64Bit()) {
150 String32(*SymtabF, name); // st_name
151 String8(*SymtabF, info); // st_info
152 String8(*SymtabF, other); // st_other
153 String16(*SymtabF, Index); // st_shndx
154 String64(*SymtabF, value); // st_value
155 String64(*SymtabF, size); // st_size
156 } else {
157 String32(*SymtabF, name); // st_name
158 String32(*SymtabF, value); // st_value
159 String32(*SymtabF, size); // st_size
160 String8(*SymtabF, info); // st_info
161 String8(*SymtabF, other); // st_other
162 String16(*SymtabF, Index); // st_shndx
166 uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
167 const MCAsmLayout &Layout) {
168 if (Data.isCommon() && Data.isExternal())
169 return Data.getCommonAlignment();
171 const MCSymbol &Symbol = Data.getSymbol();
173 if (Symbol.isAbsolute() && Symbol.isVariable()) {
174 if (const MCExpr *Value = Symbol.getVariableValue()) {
175 int64_t IntValue;
176 if (Value->EvaluateAsAbsolute(IntValue, Layout))
177 return (uint64_t)IntValue;
181 if (!Symbol.isInSection())
182 return 0;
184 if (Data.getFragment())
185 return Layout.getSymbolOffset(&Data);
187 return 0;
190 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
191 const MCAsmLayout &Layout) {
192 // The presence of symbol versions causes undefined symbols and
193 // versions declared with @@@ to be renamed.
195 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
196 ie = Asm.symbol_end(); it != ie; ++it) {
197 const MCSymbol &Alias = it->getSymbol();
198 const MCSymbol &Symbol = Alias.AliasedSymbol();
199 MCSymbolData &SD = Asm.getSymbolData(Symbol);
201 // Not an alias.
202 if (&Symbol == &Alias)
203 continue;
205 StringRef AliasName = Alias.getName();
206 size_t Pos = AliasName.find('@');
207 if (Pos == StringRef::npos)
208 continue;
210 // Aliases defined with .symvar copy the binding from the symbol they alias.
211 // This is the first place we are able to copy this information.
212 it->setExternal(SD.isExternal());
213 MCELF::SetBinding(*it, MCELF::GetBinding(SD));
215 StringRef Rest = AliasName.substr(Pos);
216 if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
217 continue;
219 // FIXME: produce a better error message.
220 if (Symbol.isUndefined() && Rest.startswith("@@") &&
221 !Rest.startswith("@@@"))
222 report_fatal_error("A @@ version cannot be undefined");
224 Renames.insert(std::make_pair(&Symbol, &Alias));
228 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
229 MCDataFragment *ShndxF,
230 ELFSymbolData &MSD,
231 const MCAsmLayout &Layout) {
232 MCSymbolData &OrigData = *MSD.SymbolData;
233 MCSymbolData &Data =
234 Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
236 bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
237 Data.getSymbol().isVariable();
239 uint8_t Binding = MCELF::GetBinding(OrigData);
240 uint8_t Visibility = MCELF::GetVisibility(OrigData);
241 uint8_t Type = MCELF::GetType(Data);
243 uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
244 uint8_t Other = Visibility;
246 uint64_t Value = SymbolValue(Data, Layout);
247 uint64_t Size = 0;
249 assert(!(Data.isCommon() && !Data.isExternal()));
251 const MCExpr *ESize = Data.getSize();
252 if (ESize) {
253 int64_t Res;
254 if (!ESize->EvaluateAsAbsolute(Res, Layout))
255 report_fatal_error("Size expression must be absolute.");
256 Size = Res;
259 // Write out the symbol table entry
260 WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
261 Size, Other, MSD.SectionIndex, IsReserved);
264 void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
265 MCDataFragment *ShndxF,
266 const MCAssembler &Asm,
267 const MCAsmLayout &Layout,
268 const SectionIndexMapTy &SectionIndexMap) {
269 // The string table must be emitted first because we need the index
270 // into the string table for all the symbol names.
271 assert(StringTable.size() && "Missing string table");
273 // FIXME: Make sure the start of the symbol table is aligned.
275 // The first entry is the undefined symbol entry.
276 WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
278 // Write the symbol table entries.
279 LastLocalSymbolIndex = LocalSymbolData.size() + 1;
280 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
281 ELFSymbolData &MSD = LocalSymbolData[i];
282 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
285 // Write out a symbol table entry for each regular section.
286 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
287 ++i) {
288 const MCSectionELF &Section =
289 static_cast<const MCSectionELF&>(i->getSection());
290 if (Section.getType() == ELF::SHT_RELA ||
291 Section.getType() == ELF::SHT_REL ||
292 Section.getType() == ELF::SHT_STRTAB ||
293 Section.getType() == ELF::SHT_SYMTAB)
294 continue;
295 WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0,
296 ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section), false);
297 LastLocalSymbolIndex++;
300 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
301 ELFSymbolData &MSD = ExternalSymbolData[i];
302 MCSymbolData &Data = *MSD.SymbolData;
303 assert(((Data.getFlags() & ELF_STB_Global) ||
304 (Data.getFlags() & ELF_STB_Weak)) &&
305 "External symbol requires STB_GLOBAL or STB_WEAK flag");
306 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
307 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
308 LastLocalSymbolIndex++;
311 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
312 ELFSymbolData &MSD = UndefinedSymbolData[i];
313 MCSymbolData &Data = *MSD.SymbolData;
314 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
315 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
316 LastLocalSymbolIndex++;
320 const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
321 const MCValue &Target,
322 const MCFragment &F) const {
323 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
324 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
325 const MCSymbol *Renamed = Renames.lookup(&Symbol);
326 const MCSymbolData &SD = Asm.getSymbolData(Symbol);
328 if (ASymbol.isUndefined()) {
329 if (Renamed)
330 return Renamed;
331 return &ASymbol;
334 if (SD.isExternal()) {
335 if (Renamed)
336 return Renamed;
337 return &Symbol;
340 const MCSectionELF &Section =
341 static_cast<const MCSectionELF&>(ASymbol.getSection());
342 const SectionKind secKind = Section.getKind();
344 if (secKind.isBSS())
345 return ExplicitRelSym(Asm, Target, F, true);
347 if (secKind.isThreadLocal()) {
348 if (Renamed)
349 return Renamed;
350 return &Symbol;
353 MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
354 const MCSectionELF &Sec2 =
355 static_cast<const MCSectionELF&>(F.getParent()->getSection());
357 if (&Sec2 != &Section &&
358 (Kind == MCSymbolRefExpr::VK_PLT ||
359 Kind == MCSymbolRefExpr::VK_GOTPCREL ||
360 Kind == MCSymbolRefExpr::VK_GOTOFF)) {
361 if (Renamed)
362 return Renamed;
363 return &Symbol;
366 if (Section.getFlags() & ELF::SHF_MERGE) {
367 if (Target.getConstant() == 0)
368 return NULL;
369 if (Renamed)
370 return Renamed;
371 return &Symbol;
374 return ExplicitRelSym(Asm, Target, F, false);
378 void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
379 const MCAsmLayout &Layout,
380 const MCFragment *Fragment,
381 const MCFixup &Fixup,
382 MCValue Target,
383 uint64_t &FixedValue) {
384 int64_t Addend = 0;
385 int Index = 0;
386 int64_t Value = Target.getConstant();
387 const MCSymbol *RelocSymbol = NULL;
389 bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
390 if (!Target.isAbsolute()) {
391 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
392 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
393 RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
395 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
396 const MCSymbol &SymbolB = RefB->getSymbol();
397 MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
398 IsPCRel = true;
400 // Offset of the symbol in the section
401 int64_t a = Layout.getSymbolOffset(&SDB);
403 // Ofeset of the relocation in the section
404 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
405 Value += b - a;
408 if (!RelocSymbol) {
409 MCSymbolData &SD = Asm.getSymbolData(ASymbol);
410 MCFragment *F = SD.getFragment();
412 Index = F->getParent()->getOrdinal() + 1;
414 // Offset of the symbol in the section
415 Value += Layout.getSymbolOffset(&SD);
416 } else {
417 if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
418 WeakrefUsedInReloc.insert(RelocSymbol);
419 else
420 UsedInReloc.insert(RelocSymbol);
421 Index = -1;
423 Addend = Value;
424 // Compensate for the addend on i386.
425 if (is64Bit())
426 Value = 0;
429 FixedValue = Value;
430 unsigned Type = GetRelocType(Target, Fixup, IsPCRel,
431 (RelocSymbol != 0), Addend);
433 uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) +
434 Fixup.getOffset();
436 if (!hasRelocationAddend())
437 Addend = 0;
438 ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend);
439 Relocations[Fragment->getParent()].push_back(ERE);
443 uint64_t
444 ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
445 const MCSymbol *S) {
446 MCSymbolData &SD = Asm.getSymbolData(*S);
447 return SD.getIndex();
450 bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm,
451 const MCSymbolData &Data,
452 bool Used, bool Renamed) {
453 if (Data.getFlags() & ELF_Other_Weakref)
454 return false;
456 if (Used)
457 return true;
459 if (Renamed)
460 return false;
462 const MCSymbol &Symbol = Data.getSymbol();
464 if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
465 return true;
467 const MCSymbol &A = Symbol.AliasedSymbol();
468 if (Symbol.isVariable() && !A.isVariable() && A.isUndefined())
469 return false;
471 bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL;
472 if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal)
473 return false;
475 if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
476 return false;
478 if (Symbol.isTemporary())
479 return false;
481 return true;
484 bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature,
485 bool isUsedInReloc) {
486 if (Data.isExternal())
487 return false;
489 const MCSymbol &Symbol = Data.getSymbol();
490 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
492 if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
493 if (isSignature && !isUsedInReloc)
494 return true;
496 return false;
499 return true;
502 void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
503 SectionIndexMapTy &SectionIndexMap,
504 const RelMapTy &RelMap) {
505 unsigned Index = 1;
506 for (MCAssembler::iterator it = Asm.begin(),
507 ie = Asm.end(); it != ie; ++it) {
508 const MCSectionELF &Section =
509 static_cast<const MCSectionELF &>(it->getSection());
510 if (Section.getType() != ELF::SHT_GROUP)
511 continue;
512 SectionIndexMap[&Section] = Index++;
515 for (MCAssembler::iterator it = Asm.begin(),
516 ie = Asm.end(); it != ie; ++it) {
517 const MCSectionELF &Section =
518 static_cast<const MCSectionELF &>(it->getSection());
519 if (Section.getType() == ELF::SHT_GROUP ||
520 Section.getType() == ELF::SHT_REL ||
521 Section.getType() == ELF::SHT_RELA)
522 continue;
523 SectionIndexMap[&Section] = Index++;
524 const MCSectionELF *RelSection = RelMap.lookup(&Section);
525 if (RelSection)
526 SectionIndexMap[RelSection] = Index++;
530 void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
531 const SectionIndexMapTy &SectionIndexMap,
532 RevGroupMapTy RevGroupMap,
533 unsigned NumRegularSections) {
534 // FIXME: Is this the correct place to do this?
535 if (NeedsGOT) {
536 llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
537 MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
538 MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
539 Data.setExternal(true);
540 MCELF::SetBinding(Data, ELF::STB_GLOBAL);
543 // Index 0 is always the empty string.
544 StringMap<uint64_t> StringIndexMap;
545 StringTable += '\x00';
547 // FIXME: We could optimize suffixes in strtab in the same way we
548 // optimize them in shstrtab.
550 // Add the data for the symbols.
551 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
552 ie = Asm.symbol_end(); it != ie; ++it) {
553 const MCSymbol &Symbol = it->getSymbol();
555 bool Used = UsedInReloc.count(&Symbol);
556 bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
557 bool isSignature = RevGroupMap.count(&Symbol);
559 if (!isInSymtab(Asm, *it,
560 Used || WeakrefUsed || isSignature,
561 Renames.count(&Symbol)))
562 continue;
564 ELFSymbolData MSD;
565 MSD.SymbolData = it;
566 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
568 // Undefined symbols are global, but this is the first place we
569 // are able to set it.
570 bool Local = isLocal(*it, isSignature, Used);
571 if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) {
572 MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
573 MCELF::SetBinding(*it, ELF::STB_GLOBAL);
574 MCELF::SetBinding(SD, ELF::STB_GLOBAL);
577 if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
578 MCELF::SetBinding(*it, ELF::STB_WEAK);
580 if (it->isCommon()) {
581 assert(!Local);
582 MSD.SectionIndex = ELF::SHN_COMMON;
583 } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
584 MSD.SectionIndex = ELF::SHN_ABS;
585 } else if (RefSymbol.isUndefined()) {
586 if (isSignature && !Used)
587 MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
588 else
589 MSD.SectionIndex = ELF::SHN_UNDEF;
590 } else {
591 const MCSectionELF &Section =
592 static_cast<const MCSectionELF&>(RefSymbol.getSection());
593 MSD.SectionIndex = SectionIndexMap.lookup(&Section);
594 if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
595 NeedsSymtabShndx = true;
596 assert(MSD.SectionIndex && "Invalid section index!");
599 // The @@@ in symbol version is replaced with @ in undefined symbols and
600 // @@ in defined ones.
601 StringRef Name = Symbol.getName();
602 SmallString<32> Buf;
604 size_t Pos = Name.find("@@@");
605 if (Pos != StringRef::npos) {
606 Buf += Name.substr(0, Pos);
607 unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
608 Buf += Name.substr(Pos + Skip);
609 Name = Buf;
612 uint64_t &Entry = StringIndexMap[Name];
613 if (!Entry) {
614 Entry = StringTable.size();
615 StringTable += Name;
616 StringTable += '\x00';
618 MSD.StringIndex = Entry;
619 if (MSD.SectionIndex == ELF::SHN_UNDEF)
620 UndefinedSymbolData.push_back(MSD);
621 else if (Local)
622 LocalSymbolData.push_back(MSD);
623 else
624 ExternalSymbolData.push_back(MSD);
627 // Symbols are required to be in lexicographic order.
628 array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
629 array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
630 array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
632 // Set the symbol indices. Local symbols must come before all other
633 // symbols with non-local bindings.
634 unsigned Index = 1;
635 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
636 LocalSymbolData[i].SymbolData->setIndex(Index++);
638 Index += NumRegularSections;
640 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
641 ExternalSymbolData[i].SymbolData->setIndex(Index++);
642 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
643 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
646 void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm,
647 MCAsmLayout &Layout,
648 RelMapTy &RelMap) {
649 for (MCAssembler::const_iterator it = Asm.begin(),
650 ie = Asm.end(); it != ie; ++it) {
651 const MCSectionData &SD = *it;
652 if (Relocations[&SD].empty())
653 continue;
655 MCContext &Ctx = Asm.getContext();
656 const MCSectionELF &Section =
657 static_cast<const MCSectionELF&>(SD.getSection());
659 const StringRef SectionName = Section.getSectionName();
660 std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel";
661 RelaSectionName += SectionName;
663 unsigned EntrySize;
664 if (hasRelocationAddend())
665 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
666 else
667 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
669 const MCSectionELF *RelaSection =
670 Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ?
671 ELF::SHT_RELA : ELF::SHT_REL, 0,
672 SectionKind::getReadOnly(),
673 EntrySize, "");
674 RelMap[&Section] = RelaSection;
675 Asm.getOrCreateSectionData(*RelaSection);
679 void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
680 const RelMapTy &RelMap) {
681 for (MCAssembler::const_iterator it = Asm.begin(),
682 ie = Asm.end(); it != ie; ++it) {
683 const MCSectionData &SD = *it;
684 const MCSectionELF &Section =
685 static_cast<const MCSectionELF&>(SD.getSection());
687 const MCSectionELF *RelaSection = RelMap.lookup(&Section);
688 if (!RelaSection)
689 continue;
690 MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
691 RelaSD.setAlignment(is64Bit() ? 8 : 4);
693 MCDataFragment *F = new MCDataFragment(&RelaSD);
694 WriteRelocationsFragment(Asm, F, &*it);
698 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
699 uint64_t Flags, uint64_t Address,
700 uint64_t Offset, uint64_t Size,
701 uint32_t Link, uint32_t Info,
702 uint64_t Alignment,
703 uint64_t EntrySize) {
704 Write32(Name); // sh_name: index into string table
705 Write32(Type); // sh_type
706 WriteWord(Flags); // sh_flags
707 WriteWord(Address); // sh_addr
708 WriteWord(Offset); // sh_offset
709 WriteWord(Size); // sh_size
710 Write32(Link); // sh_link
711 Write32(Info); // sh_info
712 WriteWord(Alignment); // sh_addralign
713 WriteWord(EntrySize); // sh_entsize
716 void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
717 MCDataFragment *F,
718 const MCSectionData *SD) {
719 std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
720 // sort by the r_offset just like gnu as does
721 array_pod_sort(Relocs.begin(), Relocs.end());
723 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
724 ELFRelocationEntry entry = Relocs[e - i - 1];
726 if (!entry.Index)
728 else if (entry.Index < 0)
729 entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
730 else
731 entry.Index += LocalSymbolData.size();
732 if (is64Bit()) {
733 String64(*F, entry.r_offset);
735 struct ELF::Elf64_Rela ERE64;
736 ERE64.setSymbolAndType(entry.Index, entry.Type);
737 String64(*F, ERE64.r_info);
739 if (hasRelocationAddend())
740 String64(*F, entry.r_addend);
741 } else {
742 String32(*F, entry.r_offset);
744 struct ELF::Elf32_Rela ERE32;
745 ERE32.setSymbolAndType(entry.Index, entry.Type);
746 String32(*F, ERE32.r_info);
748 if (hasRelocationAddend())
749 String32(*F, entry.r_addend);
754 static int compareBySuffix(const void *a, const void *b) {
755 const MCSectionELF *secA = *static_cast<const MCSectionELF* const *>(a);
756 const MCSectionELF *secB = *static_cast<const MCSectionELF* const *>(b);
757 const StringRef &NameA = secA->getSectionName();
758 const StringRef &NameB = secB->getSectionName();
759 const unsigned sizeA = NameA.size();
760 const unsigned sizeB = NameB.size();
761 const unsigned len = std::min(sizeA, sizeB);
762 for (unsigned int i = 0; i < len; ++i) {
763 char ca = NameA[sizeA - i - 1];
764 char cb = NameB[sizeB - i - 1];
765 if (ca != cb)
766 return cb - ca;
769 return sizeB - sizeA;
772 void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
773 MCAsmLayout &Layout,
774 SectionIndexMapTy &SectionIndexMap,
775 const RelMapTy &RelMap) {
776 MCContext &Ctx = Asm.getContext();
777 MCDataFragment *F;
779 unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
781 // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
782 const MCSectionELF *ShstrtabSection =
783 Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
784 SectionKind::getReadOnly());
785 MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
786 ShstrtabSD.setAlignment(1);
788 const MCSectionELF *SymtabSection =
789 Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
790 SectionKind::getReadOnly(),
791 EntrySize, "");
792 MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
793 SymtabSD.setAlignment(is64Bit() ? 8 : 4);
795 MCSectionData *SymtabShndxSD = NULL;
797 if (NeedsSymtabShndx) {
798 const MCSectionELF *SymtabShndxSection =
799 Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
800 SectionKind::getReadOnly(), 4, "");
801 SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
802 SymtabShndxSD->setAlignment(4);
805 const MCSectionELF *StrtabSection;
806 StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
807 SectionKind::getReadOnly());
808 MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
809 StrtabSD.setAlignment(1);
811 ComputeIndexMap(Asm, SectionIndexMap, RelMap);
813 ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection);
814 SymbolTableIndex = SectionIndexMap.lookup(SymtabSection);
815 StringTableIndex = SectionIndexMap.lookup(StrtabSection);
817 // Symbol table
818 F = new MCDataFragment(&SymtabSD);
819 MCDataFragment *ShndxF = NULL;
820 if (NeedsSymtabShndx) {
821 ShndxF = new MCDataFragment(SymtabShndxSD);
823 WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
825 F = new MCDataFragment(&StrtabSD);
826 F->getContents().append(StringTable.begin(), StringTable.end());
828 F = new MCDataFragment(&ShstrtabSD);
830 std::vector<const MCSectionELF*> Sections;
831 for (MCAssembler::const_iterator it = Asm.begin(),
832 ie = Asm.end(); it != ie; ++it) {
833 const MCSectionELF &Section =
834 static_cast<const MCSectionELF&>(it->getSection());
835 Sections.push_back(&Section);
837 array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix);
839 // Section header string table.
841 // The first entry of a string table holds a null character so skip
842 // section 0.
843 uint64_t Index = 1;
844 F->getContents() += '\x00';
846 for (unsigned int I = 0, E = Sections.size(); I != E; ++I) {
847 const MCSectionELF &Section = *Sections[I];
849 StringRef Name = Section.getSectionName();
850 if (I != 0) {
851 StringRef PreviousName = Sections[I - 1]->getSectionName();
852 if (PreviousName.endswith(Name)) {
853 SectionStringTableIndex[&Section] = Index - Name.size() - 1;
854 continue;
857 // Remember the index into the string table so we can write it
858 // into the sh_name field of the section header table.
859 SectionStringTableIndex[&Section] = Index;
861 Index += Name.size() + 1;
862 F->getContents() += Name;
863 F->getContents() += '\x00';
867 void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
868 MCAsmLayout &Layout,
869 GroupMapTy &GroupMap,
870 RevGroupMapTy &RevGroupMap,
871 SectionIndexMapTy &SectionIndexMap,
872 const RelMapTy &RelMap) {
873 // Create the .note.GNU-stack section if needed.
874 MCContext &Ctx = Asm.getContext();
875 if (Asm.getNoExecStack()) {
876 const MCSectionELF *GnuStackSection =
877 Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0,
878 SectionKind::getReadOnly());
879 Asm.getOrCreateSectionData(*GnuStackSection);
882 // Build the groups
883 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
884 it != ie; ++it) {
885 const MCSectionELF &Section =
886 static_cast<const MCSectionELF&>(it->getSection());
887 if (!(Section.getFlags() & ELF::SHF_GROUP))
888 continue;
890 const MCSymbol *SignatureSymbol = Section.getGroup();
891 Asm.getOrCreateSymbolData(*SignatureSymbol);
892 const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
893 if (!Group) {
894 Group = Ctx.CreateELFGroupSection();
895 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
896 Data.setAlignment(4);
897 MCDataFragment *F = new MCDataFragment(&Data);
898 String32(*F, ELF::GRP_COMDAT);
900 GroupMap[Group] = SignatureSymbol;
903 ComputeIndexMap(Asm, SectionIndexMap, RelMap);
905 // Add sections to the groups
906 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
907 it != ie; ++it) {
908 const MCSectionELF &Section =
909 static_cast<const MCSectionELF&>(it->getSection());
910 if (!(Section.getFlags() & ELF::SHF_GROUP))
911 continue;
912 const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
913 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
914 // FIXME: we could use the previous fragment
915 MCDataFragment *F = new MCDataFragment(&Data);
916 unsigned Index = SectionIndexMap.lookup(&Section);
917 String32(*F, Index);
921 void ELFObjectWriter::WriteSection(MCAssembler &Asm,
922 const SectionIndexMapTy &SectionIndexMap,
923 uint32_t GroupSymbolIndex,
924 uint64_t Offset, uint64_t Size,
925 uint64_t Alignment,
926 const MCSectionELF &Section) {
927 uint64_t sh_link = 0;
928 uint64_t sh_info = 0;
930 switch(Section.getType()) {
931 case ELF::SHT_DYNAMIC:
932 sh_link = SectionStringTableIndex[&Section];
933 sh_info = 0;
934 break;
936 case ELF::SHT_REL:
937 case ELF::SHT_RELA: {
938 const MCSectionELF *SymtabSection;
939 const MCSectionELF *InfoSection;
940 SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
942 SectionKind::getReadOnly());
943 sh_link = SectionIndexMap.lookup(SymtabSection);
944 assert(sh_link && ".symtab not found");
946 // Remove ".rel" and ".rela" prefixes.
947 unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
948 StringRef SectionName = Section.getSectionName().substr(SecNameLen);
950 InfoSection = Asm.getContext().getELFSection(SectionName,
951 ELF::SHT_PROGBITS, 0,
952 SectionKind::getReadOnly());
953 sh_info = SectionIndexMap.lookup(InfoSection);
954 break;
957 case ELF::SHT_SYMTAB:
958 case ELF::SHT_DYNSYM:
959 sh_link = StringTableIndex;
960 sh_info = LastLocalSymbolIndex;
961 break;
963 case ELF::SHT_SYMTAB_SHNDX:
964 sh_link = SymbolTableIndex;
965 break;
967 case ELF::SHT_PROGBITS:
968 case ELF::SHT_STRTAB:
969 case ELF::SHT_NOBITS:
970 case ELF::SHT_NOTE:
971 case ELF::SHT_NULL:
972 case ELF::SHT_ARM_ATTRIBUTES:
973 case ELF::SHT_INIT_ARRAY:
974 case ELF::SHT_FINI_ARRAY:
975 case ELF::SHT_PREINIT_ARRAY:
976 case ELF::SHT_X86_64_UNWIND:
977 // Nothing to do.
978 break;
980 case ELF::SHT_GROUP: {
981 sh_link = SymbolTableIndex;
982 sh_info = GroupSymbolIndex;
983 break;
986 default:
987 assert(0 && "FIXME: sh_type value not supported!");
988 break;
991 WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
992 Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
993 Alignment, Section.getEntrySize());
996 bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) {
997 return SD.getOrdinal() == ~UINT32_C(0) &&
998 !SD.getSection().isVirtualSection();
1001 uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) {
1002 uint64_t Ret = 0;
1003 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1004 ++i) {
1005 const MCFragment &F = *i;
1006 assert(F.getKind() == MCFragment::FT_Data);
1007 Ret += cast<MCDataFragment>(F).getContents().size();
1009 return Ret;
1012 uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout,
1013 const MCSectionData &SD) {
1014 if (IsELFMetaDataSection(SD))
1015 return DataSectionSize(SD);
1016 return Layout.getSectionFileSize(&SD);
1019 uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout,
1020 const MCSectionData &SD) {
1021 if (IsELFMetaDataSection(SD))
1022 return DataSectionSize(SD);
1023 return Layout.getSectionAddressSize(&SD);
1026 void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
1027 const MCAsmLayout &Layout,
1028 const MCSectionELF &Section) {
1029 uint64_t FileOff = OS.tell();
1030 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1032 uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment());
1033 WriteZeros(Padding);
1034 FileOff += Padding;
1036 FileOff += GetSectionFileSize(Layout, SD);
1038 if (IsELFMetaDataSection(SD)) {
1039 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1040 ++i) {
1041 const MCFragment &F = *i;
1042 assert(F.getKind() == MCFragment::FT_Data);
1043 WriteBytes(cast<MCDataFragment>(F).getContents().str());
1045 } else {
1046 Asm.WriteSectionData(&SD, Layout);
1050 void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm,
1051 const GroupMapTy &GroupMap,
1052 const MCAsmLayout &Layout,
1053 const SectionIndexMapTy &SectionIndexMap,
1054 const SectionOffsetMapTy &SectionOffsetMap) {
1055 const unsigned NumSections = Asm.size() + 1;
1057 std::vector<const MCSectionELF*> Sections;
1058 Sections.resize(NumSections - 1);
1060 for (SectionIndexMapTy::const_iterator i=
1061 SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
1062 const std::pair<const MCSectionELF*, uint32_t> &p = *i;
1063 Sections[p.second - 1] = p.first;
1066 // Null section first.
1067 uint64_t FirstSectionSize =
1068 NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
1069 uint32_t FirstSectionLink =
1070 ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
1071 WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
1073 for (unsigned i = 0; i < NumSections - 1; ++i) {
1074 const MCSectionELF &Section = *Sections[i];
1075 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1076 uint32_t GroupSymbolIndex;
1077 if (Section.getType() != ELF::SHT_GROUP)
1078 GroupSymbolIndex = 0;
1079 else
1080 GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm,
1081 GroupMap.lookup(&Section));
1083 uint64_t Size = GetSectionAddressSize(Layout, SD);
1085 WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
1086 SectionOffsetMap.lookup(&Section), Size,
1087 SD.getAlignment(), Section);
1091 void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm,
1092 std::vector<const MCSectionELF*> &Sections) {
1093 for (MCAssembler::iterator it = Asm.begin(),
1094 ie = Asm.end(); it != ie; ++it) {
1095 const MCSectionELF &Section =
1096 static_cast<const MCSectionELF &>(it->getSection());
1097 if (Section.getType() == ELF::SHT_GROUP)
1098 Sections.push_back(&Section);
1101 for (MCAssembler::iterator it = Asm.begin(),
1102 ie = Asm.end(); it != ie; ++it) {
1103 const MCSectionELF &Section =
1104 static_cast<const MCSectionELF &>(it->getSection());
1105 if (Section.getType() != ELF::SHT_GROUP &&
1106 Section.getType() != ELF::SHT_REL &&
1107 Section.getType() != ELF::SHT_RELA)
1108 Sections.push_back(&Section);
1111 for (MCAssembler::iterator it = Asm.begin(),
1112 ie = Asm.end(); it != ie; ++it) {
1113 const MCSectionELF &Section =
1114 static_cast<const MCSectionELF &>(it->getSection());
1115 if (Section.getType() == ELF::SHT_REL ||
1116 Section.getType() == ELF::SHT_RELA)
1117 Sections.push_back(&Section);
1121 void ELFObjectWriter::WriteObject(MCAssembler &Asm,
1122 const MCAsmLayout &Layout) {
1123 GroupMapTy GroupMap;
1124 RevGroupMapTy RevGroupMap;
1125 SectionIndexMapTy SectionIndexMap;
1127 unsigned NumUserSections = Asm.size();
1129 DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
1130 CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
1132 const unsigned NumUserAndRelocSections = Asm.size();
1133 CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
1134 RevGroupMap, SectionIndexMap, RelMap);
1135 const unsigned AllSections = Asm.size();
1136 const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
1138 unsigned NumRegularSections = NumUserSections + NumIndexedSections;
1140 // Compute symbol table information.
1141 ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections);
1144 WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
1146 CreateMetadataSections(const_cast<MCAssembler&>(Asm),
1147 const_cast<MCAsmLayout&>(Layout),
1148 SectionIndexMap,
1149 RelMap);
1151 uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
1152 uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
1153 sizeof(ELF::Elf32_Ehdr);
1154 uint64_t FileOff = HeaderSize;
1156 std::vector<const MCSectionELF*> Sections;
1157 ComputeSectionOrder(Asm, Sections);
1158 unsigned NumSections = Sections.size();
1159 SectionOffsetMapTy SectionOffsetMap;
1160 for (unsigned i = 0; i < NumRegularSections + 1; ++i) {
1161 const MCSectionELF &Section = *Sections[i];
1162 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1164 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1166 // Remember the offset into the file for this section.
1167 SectionOffsetMap[&Section] = FileOff;
1169 // Get the size of the section in the output file (including padding).
1170 FileOff += GetSectionFileSize(Layout, SD);
1173 FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
1175 const unsigned SectionHeaderOffset = FileOff - HeaderSize;
1177 uint64_t SectionHeaderEntrySize = is64Bit() ?
1178 sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr);
1179 FileOff += (NumSections + 1) * SectionHeaderEntrySize;
1181 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) {
1182 const MCSectionELF &Section = *Sections[i];
1183 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1185 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1187 // Remember the offset into the file for this section.
1188 SectionOffsetMap[&Section] = FileOff;
1190 // Get the size of the section in the output file (including padding).
1191 FileOff += GetSectionFileSize(Layout, SD);
1194 // Write out the ELF header ...
1195 WriteHeader(SectionHeaderOffset, NumSections + 1);
1197 // ... then the regular sections ...
1198 // + because of .shstrtab
1199 for (unsigned i = 0; i < NumRegularSections + 1; ++i)
1200 WriteDataSectionData(Asm, Layout, *Sections[i]);
1202 FileOff = OS.tell();
1203 uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment);
1204 WriteZeros(Padding);
1206 // ... then the section header table ...
1207 WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap,
1208 SectionOffsetMap);
1210 FileOff = OS.tell();
1212 // ... and then the remainting sections ...
1213 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)
1214 WriteDataSectionData(Asm, Layout, *Sections[i]);
1217 bool
1218 ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
1219 const MCSymbolData &DataA,
1220 const MCFragment &FB,
1221 bool InSet,
1222 bool IsPCRel) const {
1223 if (DataA.getFlags() & ELF_STB_Weak)
1224 return false;
1225 return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
1226 Asm, DataA, FB,InSet, IsPCRel);
1229 MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
1230 raw_ostream &OS,
1231 bool IsLittleEndian) {
1232 switch (MOTW->getEMachine()) {
1233 case ELF::EM_386:
1234 case ELF::EM_X86_64:
1235 return new X86ELFObjectWriter(MOTW, OS, IsLittleEndian); break;
1236 case ELF::EM_ARM:
1237 return new ARMELFObjectWriter(MOTW, OS, IsLittleEndian); break;
1238 case ELF::EM_MBLAZE:
1239 return new MBlazeELFObjectWriter(MOTW, OS, IsLittleEndian); break;
1240 default: llvm_unreachable("Unsupported architecture"); break;
1245 /// START OF SUBCLASSES for ELFObjectWriter
1246 //===- ARMELFObjectWriter -------------------------------------------===//
1248 ARMELFObjectWriter::ARMELFObjectWriter(MCELFObjectTargetWriter *MOTW,
1249 raw_ostream &_OS,
1250 bool IsLittleEndian)
1251 : ELFObjectWriter(MOTW, _OS, IsLittleEndian)
1254 ARMELFObjectWriter::~ARMELFObjectWriter()
1257 // FIXME: get the real EABI Version from the Triple.
1258 void ARMELFObjectWriter::WriteEFlags() {
1259 Write32(ELF::EF_ARM_EABIMASK & DefaultEABIVersion);
1262 // In ARM, _MergedGlobals and other most symbols get emitted directly.
1263 // I.e. not as an offset to a section symbol.
1264 // This code is a first-cut approximation of what ARM/gcc does.
1266 const MCSymbol *ARMELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
1267 const MCValue &Target,
1268 const MCFragment &F,
1269 bool IsBSS) const {
1270 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
1271 bool EmitThisSym = false;
1273 if (IsBSS) {
1274 EmitThisSym = StringSwitch<bool>(Symbol.getName())
1275 .Case("_MergedGlobals", true)
1276 .Default(false);
1277 } else {
1278 EmitThisSym = StringSwitch<bool>(Symbol.getName())
1279 .Case("_MergedGlobals", true)
1280 .StartsWith(".L.str", true)
1281 .Default(false);
1283 if (EmitThisSym)
1284 return &Symbol;
1285 if (! Symbol.isTemporary())
1286 return &Symbol;
1287 return NULL;
1290 unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
1291 const MCFixup &Fixup,
1292 bool IsPCRel,
1293 bool IsRelocWithSymbol,
1294 int64_t Addend) {
1295 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1296 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1298 unsigned Type = 0;
1299 if (IsPCRel) {
1300 switch ((unsigned)Fixup.getKind()) {
1301 default: assert(0 && "Unimplemented");
1302 case FK_Data_4:
1303 switch (Modifier) {
1304 default: llvm_unreachable("Unsupported Modifier");
1305 case MCSymbolRefExpr::VK_None:
1306 Type = ELF::R_ARM_BASE_PREL;
1307 break;
1308 case MCSymbolRefExpr::VK_ARM_TLSGD:
1309 assert(0 && "unimplemented");
1310 break;
1311 case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
1312 Type = ELF::R_ARM_TLS_IE32;
1313 break;
1315 break;
1316 case ARM::fixup_arm_uncondbranch:
1317 switch (Modifier) {
1318 case MCSymbolRefExpr::VK_ARM_PLT:
1319 Type = ELF::R_ARM_PLT32;
1320 break;
1321 default:
1322 Type = ELF::R_ARM_CALL;
1323 break;
1325 break;
1326 case ARM::fixup_arm_condbranch:
1327 Type = ELF::R_ARM_JUMP24;
1328 break;
1329 case ARM::fixup_arm_movt_hi16:
1330 case ARM::fixup_arm_movt_hi16_pcrel:
1331 Type = ELF::R_ARM_MOVT_PREL;
1332 break;
1333 case ARM::fixup_arm_movw_lo16:
1334 case ARM::fixup_arm_movw_lo16_pcrel:
1335 Type = ELF::R_ARM_MOVW_PREL_NC;
1336 break;
1337 case ARM::fixup_t2_movt_hi16:
1338 case ARM::fixup_t2_movt_hi16_pcrel:
1339 Type = ELF::R_ARM_THM_MOVT_PREL;
1340 break;
1341 case ARM::fixup_t2_movw_lo16:
1342 case ARM::fixup_t2_movw_lo16_pcrel:
1343 Type = ELF::R_ARM_THM_MOVW_PREL_NC;
1344 break;
1346 } else {
1347 switch ((unsigned)Fixup.getKind()) {
1348 default: llvm_unreachable("invalid fixup kind!");
1349 case FK_Data_4:
1350 switch (Modifier) {
1351 default: llvm_unreachable("Unsupported Modifier"); break;
1352 case MCSymbolRefExpr::VK_ARM_GOT:
1353 Type = ELF::R_ARM_GOT_BREL;
1354 break;
1355 case MCSymbolRefExpr::VK_ARM_TLSGD:
1356 Type = ELF::R_ARM_TLS_GD32;
1357 break;
1358 case MCSymbolRefExpr::VK_ARM_TPOFF:
1359 Type = ELF::R_ARM_TLS_LE32;
1360 break;
1361 case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
1362 Type = ELF::R_ARM_TLS_IE32;
1363 break;
1364 case MCSymbolRefExpr::VK_None:
1365 Type = ELF::R_ARM_ABS32;
1366 break;
1367 case MCSymbolRefExpr::VK_ARM_GOTOFF:
1368 Type = ELF::R_ARM_GOTOFF32;
1369 break;
1371 break;
1372 case ARM::fixup_arm_ldst_pcrel_12:
1373 case ARM::fixup_arm_pcrel_10:
1374 case ARM::fixup_arm_adr_pcrel_12:
1375 case ARM::fixup_arm_thumb_bl:
1376 case ARM::fixup_arm_thumb_cb:
1377 case ARM::fixup_arm_thumb_cp:
1378 case ARM::fixup_arm_thumb_br:
1379 assert(0 && "Unimplemented");
1380 break;
1381 case ARM::fixup_arm_uncondbranch:
1382 Type = ELF::R_ARM_CALL;
1383 break;
1384 case ARM::fixup_arm_condbranch:
1385 Type = ELF::R_ARM_JUMP24;
1386 break;
1387 case ARM::fixup_arm_movt_hi16:
1388 Type = ELF::R_ARM_MOVT_ABS;
1389 break;
1390 case ARM::fixup_arm_movw_lo16:
1391 Type = ELF::R_ARM_MOVW_ABS_NC;
1392 break;
1393 case ARM::fixup_t2_movt_hi16:
1394 Type = ELF::R_ARM_THM_MOVT_ABS;
1395 break;
1396 case ARM::fixup_t2_movw_lo16:
1397 Type = ELF::R_ARM_THM_MOVW_ABS_NC;
1398 break;
1402 if (RelocNeedsGOT(Modifier))
1403 NeedsGOT = true;
1405 return Type;
1408 //===- MBlazeELFObjectWriter -------------------------------------------===//
1410 MBlazeELFObjectWriter::MBlazeELFObjectWriter(MCELFObjectTargetWriter *MOTW,
1411 raw_ostream &_OS,
1412 bool IsLittleEndian)
1413 : ELFObjectWriter(MOTW, _OS, IsLittleEndian) {
1416 MBlazeELFObjectWriter::~MBlazeELFObjectWriter() {
1419 unsigned MBlazeELFObjectWriter::GetRelocType(const MCValue &Target,
1420 const MCFixup &Fixup,
1421 bool IsPCRel,
1422 bool IsRelocWithSymbol,
1423 int64_t Addend) {
1424 // determine the type of the relocation
1425 unsigned Type;
1426 if (IsPCRel) {
1427 switch ((unsigned)Fixup.getKind()) {
1428 default:
1429 llvm_unreachable("Unimplemented");
1430 case FK_PCRel_4:
1431 Type = ELF::R_MICROBLAZE_64_PCREL;
1432 break;
1433 case FK_PCRel_2:
1434 Type = ELF::R_MICROBLAZE_32_PCREL;
1435 break;
1437 } else {
1438 switch ((unsigned)Fixup.getKind()) {
1439 default: llvm_unreachable("invalid fixup kind!");
1440 case FK_Data_4:
1441 Type = ((IsRelocWithSymbol || Addend !=0)
1442 ? ELF::R_MICROBLAZE_32
1443 : ELF::R_MICROBLAZE_64);
1444 break;
1445 case FK_Data_2:
1446 Type = ELF::R_MICROBLAZE_32;
1447 break;
1450 return Type;
1453 //===- X86ELFObjectWriter -------------------------------------------===//
1456 X86ELFObjectWriter::X86ELFObjectWriter(MCELFObjectTargetWriter *MOTW,
1457 raw_ostream &_OS,
1458 bool IsLittleEndian)
1459 : ELFObjectWriter(MOTW, _OS, IsLittleEndian)
1462 X86ELFObjectWriter::~X86ELFObjectWriter()
1465 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
1466 const MCFixup &Fixup,
1467 bool IsPCRel,
1468 bool IsRelocWithSymbol,
1469 int64_t Addend) {
1470 // determine the type of the relocation
1472 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1473 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1474 unsigned Type;
1475 if (is64Bit()) {
1476 if (IsPCRel) {
1477 switch ((unsigned)Fixup.getKind()) {
1478 default: llvm_unreachable("invalid fixup kind!");
1479 case FK_PCRel_8:
1480 assert(Modifier == MCSymbolRefExpr::VK_None);
1481 Type = ELF::R_X86_64_PC64;
1482 break;
1483 case X86::reloc_signed_4byte:
1484 case X86::reloc_riprel_4byte_movq_load:
1485 case FK_Data_4: // FIXME?
1486 case X86::reloc_riprel_4byte:
1487 case FK_PCRel_4:
1488 switch (Modifier) {
1489 default:
1490 llvm_unreachable("Unimplemented");
1491 case MCSymbolRefExpr::VK_None:
1492 Type = ELF::R_X86_64_PC32;
1493 break;
1494 case MCSymbolRefExpr::VK_PLT:
1495 Type = ELF::R_X86_64_PLT32;
1496 break;
1497 case MCSymbolRefExpr::VK_GOTPCREL:
1498 Type = ELF::R_X86_64_GOTPCREL;
1499 break;
1500 case MCSymbolRefExpr::VK_GOTTPOFF:
1501 Type = ELF::R_X86_64_GOTTPOFF;
1502 break;
1503 case MCSymbolRefExpr::VK_TLSGD:
1504 Type = ELF::R_X86_64_TLSGD;
1505 break;
1506 case MCSymbolRefExpr::VK_TLSLD:
1507 Type = ELF::R_X86_64_TLSLD;
1508 break;
1510 break;
1511 case FK_PCRel_2:
1512 assert(Modifier == MCSymbolRefExpr::VK_None);
1513 Type = ELF::R_X86_64_PC16;
1514 break;
1515 case FK_PCRel_1:
1516 assert(Modifier == MCSymbolRefExpr::VK_None);
1517 Type = ELF::R_X86_64_PC8;
1518 break;
1520 } else {
1521 switch ((unsigned)Fixup.getKind()) {
1522 default: llvm_unreachable("invalid fixup kind!");
1523 case FK_Data_8: Type = ELF::R_X86_64_64; break;
1524 case X86::reloc_signed_4byte:
1525 assert(isInt<32>(Target.getConstant()));
1526 switch (Modifier) {
1527 default:
1528 llvm_unreachable("Unimplemented");
1529 case MCSymbolRefExpr::VK_None:
1530 Type = ELF::R_X86_64_32S;
1531 break;
1532 case MCSymbolRefExpr::VK_GOT:
1533 Type = ELF::R_X86_64_GOT32;
1534 break;
1535 case MCSymbolRefExpr::VK_GOTPCREL:
1536 Type = ELF::R_X86_64_GOTPCREL;
1537 break;
1538 case MCSymbolRefExpr::VK_TPOFF:
1539 Type = ELF::R_X86_64_TPOFF32;
1540 break;
1541 case MCSymbolRefExpr::VK_DTPOFF:
1542 Type = ELF::R_X86_64_DTPOFF32;
1543 break;
1545 break;
1546 case FK_Data_4:
1547 Type = ELF::R_X86_64_32;
1548 break;
1549 case FK_Data_2: Type = ELF::R_X86_64_16; break;
1550 case FK_PCRel_1:
1551 case FK_Data_1: Type = ELF::R_X86_64_8; break;
1554 } else {
1555 if (IsPCRel) {
1556 switch (Modifier) {
1557 default:
1558 llvm_unreachable("Unimplemented");
1559 case MCSymbolRefExpr::VK_None:
1560 Type = ELF::R_386_PC32;
1561 break;
1562 case MCSymbolRefExpr::VK_PLT:
1563 Type = ELF::R_386_PLT32;
1564 break;
1566 } else {
1567 switch ((unsigned)Fixup.getKind()) {
1568 default: llvm_unreachable("invalid fixup kind!");
1570 case X86::reloc_global_offset_table:
1571 Type = ELF::R_386_GOTPC;
1572 break;
1574 // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
1575 // instead?
1576 case X86::reloc_signed_4byte:
1577 case FK_PCRel_4:
1578 case FK_Data_4:
1579 switch (Modifier) {
1580 default:
1581 llvm_unreachable("Unimplemented");
1582 case MCSymbolRefExpr::VK_None:
1583 Type = ELF::R_386_32;
1584 break;
1585 case MCSymbolRefExpr::VK_GOT:
1586 Type = ELF::R_386_GOT32;
1587 break;
1588 case MCSymbolRefExpr::VK_GOTOFF:
1589 Type = ELF::R_386_GOTOFF;
1590 break;
1591 case MCSymbolRefExpr::VK_TLSGD:
1592 Type = ELF::R_386_TLS_GD;
1593 break;
1594 case MCSymbolRefExpr::VK_TPOFF:
1595 Type = ELF::R_386_TLS_LE_32;
1596 break;
1597 case MCSymbolRefExpr::VK_INDNTPOFF:
1598 Type = ELF::R_386_TLS_IE;
1599 break;
1600 case MCSymbolRefExpr::VK_NTPOFF:
1601 Type = ELF::R_386_TLS_LE;
1602 break;
1603 case MCSymbolRefExpr::VK_GOTNTPOFF:
1604 Type = ELF::R_386_TLS_GOTIE;
1605 break;
1606 case MCSymbolRefExpr::VK_TLSLDM:
1607 Type = ELF::R_386_TLS_LDM;
1608 break;
1609 case MCSymbolRefExpr::VK_DTPOFF:
1610 Type = ELF::R_386_TLS_LDO_32;
1611 break;
1613 break;
1614 case FK_Data_2: Type = ELF::R_386_16; break;
1615 case FK_PCRel_1:
1616 case FK_Data_1: Type = ELF::R_386_8; break;
1621 if (RelocNeedsGOT(Modifier))
1622 NeedsGOT = true;
1624 return Type;