1 //===-- ELFWriter.cpp - Target-independent ELF Writer code ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the target-independent ELF writer. This file writes out
11 // the ELF file in the following order:
14 // #2. '.text' section
15 // #3. '.data' section
16 // #4. '.bss' section (conceptual position in file)
18 // #X. '.shstrtab' section
21 // The entries in the section table are laid out as:
22 // #0. Null entry [required]
23 // #1. ".text" entry - the program code
24 // #2. ".data" entry - global variables with initializers. [ if needed ]
25 // #3. ".bss" entry - global variables without initializers. [ if needed ]
27 // #N. ".shstrtab" entry - String table for the section names.
29 //===----------------------------------------------------------------------===//
31 #define DEBUG_TYPE "elfwriter"
34 #include "ELFWriter.h"
35 #include "ELFCodeEmitter.h"
36 #include "llvm/Constants.h"
37 #include "llvm/Module.h"
38 #include "llvm/PassManager.h"
39 #include "llvm/DerivedTypes.h"
40 #include "llvm/CodeGen/BinaryObject.h"
41 #include "llvm/CodeGen/FileWriters.h"
42 #include "llvm/CodeGen/MachineCodeEmitter.h"
43 #include "llvm/CodeGen/MachineConstantPool.h"
44 #include "llvm/Target/TargetAsmInfo.h"
45 #include "llvm/Target/TargetData.h"
46 #include "llvm/Target/TargetELFWriterInfo.h"
47 #include "llvm/Target/TargetMachine.h"
48 #include "llvm/Support/Mangler.h"
49 #include "llvm/Support/Streams.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include "llvm/Support/Debug.h"
54 char ELFWriter::ID = 0;
55 /// AddELFWriter - Concrete function to add the ELF writer to the function pass
57 MachineCodeEmitter *llvm::AddELFWriter(PassManagerBase &PM,
60 ELFWriter *EW = new ELFWriter(O, TM);
62 return &EW->getMachineCodeEmitter();
65 //===----------------------------------------------------------------------===//
66 // ELFWriter Implementation
67 //===----------------------------------------------------------------------===//
69 ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
70 : MachineFunctionPass(&ID), O(o), TM(tm),
71 is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
72 isLittleEndian(TM.getTargetData()->isLittleEndian()),
73 ElfHdr(isLittleEndian, is64Bit) {
75 TAI = TM.getTargetAsmInfo();
76 TEW = TM.getELFWriterInfo();
78 // Create the machine code emitter object for this target.
79 MCE = new ELFCodeEmitter(*this);
81 // Inital number of sections
85 ELFWriter::~ELFWriter() {
89 // doInitialization - Emit the file header and all of the global variables for
90 // the module to the ELF file.
91 bool ELFWriter::doInitialization(Module &M) {
92 Mang = new Mangler(M);
96 // Fields e_shnum e_shstrndx are only known after all section have
97 // been emitted. They locations in the ouput buffer are recorded so
98 // to be patched up later.
102 // emitWord method behaves differently for ELF32 and ELF64, writing
103 // 4 bytes in the former and 8 in the last for *_off and *_addr elf types
105 ElfHdr.emitByte(0x7f); // e_ident[EI_MAG0]
106 ElfHdr.emitByte('E'); // e_ident[EI_MAG1]
107 ElfHdr.emitByte('L'); // e_ident[EI_MAG2]
108 ElfHdr.emitByte('F'); // e_ident[EI_MAG3]
110 ElfHdr.emitByte(TEW->getEIClass()); // e_ident[EI_CLASS]
111 ElfHdr.emitByte(TEW->getEIData()); // e_ident[EI_DATA]
112 ElfHdr.emitByte(EV_CURRENT); // e_ident[EI_VERSION]
113 ElfHdr.emitAlignment(16); // e_ident[EI_NIDENT-EI_PAD]
115 ElfHdr.emitWord16(ET_REL); // e_type
116 ElfHdr.emitWord16(TEW->getEMachine()); // e_machine = target
117 ElfHdr.emitWord32(EV_CURRENT); // e_version
118 ElfHdr.emitWord(0); // e_entry, no entry point in .o file
119 ElfHdr.emitWord(0); // e_phoff, no program header for .o
120 ELFHdr_e_shoff_Offset = ElfHdr.size();
121 ElfHdr.emitWord(0); // e_shoff = sec hdr table off in bytes
122 ElfHdr.emitWord32(TEW->getEFlags()); // e_flags = whatever the target wants
123 ElfHdr.emitWord16(TEW->getHdrSize()); // e_ehsize = ELF header size
124 ElfHdr.emitWord16(0); // e_phentsize = prog header entry size
125 ElfHdr.emitWord16(0); // e_phnum = # prog header entries = 0
127 // e_shentsize = Section header entry size
128 ElfHdr.emitWord16(TEW->getSHdrSize());
130 // e_shnum = # of section header ents
131 ELFHdr_e_shnum_Offset = ElfHdr.size();
132 ElfHdr.emitWord16(0); // Placeholder
134 // e_shstrndx = Section # of '.shstrtab'
135 ELFHdr_e_shstrndx_Offset = ElfHdr.size();
136 ElfHdr.emitWord16(0); // Placeholder
138 // Add the null section, which is required to be first in the file.
144 unsigned ELFWriter::getGlobalELFVisibility(const GlobalValue *GV) {
145 switch (GV->getVisibility()) {
147 assert(0 && "unknown visibility type");
148 case GlobalValue::DefaultVisibility:
149 return ELFSym::STV_DEFAULT;
150 case GlobalValue::HiddenVisibility:
151 return ELFSym::STV_HIDDEN;
152 case GlobalValue::ProtectedVisibility:
153 return ELFSym::STV_PROTECTED;
159 unsigned ELFWriter::getGlobalELFLinkage(const GlobalValue *GV) {
160 if (GV->hasInternalLinkage())
161 return ELFSym::STB_LOCAL;
163 if (GV->hasWeakLinkage())
164 return ELFSym::STB_WEAK;
166 return ELFSym::STB_GLOBAL;
169 // getElfSectionFlags - Get the ELF Section Header based on the
170 // flags defined in ELFTargetAsmInfo.
171 unsigned ELFWriter::getElfSectionFlags(unsigned Flags) {
172 unsigned ElfSectionFlags = ELFSection::SHF_ALLOC;
174 if (Flags & SectionFlags::Code)
175 ElfSectionFlags |= ELFSection::SHF_EXECINSTR;
176 if (Flags & SectionFlags::Writeable)
177 ElfSectionFlags |= ELFSection::SHF_WRITE;
178 if (Flags & SectionFlags::Mergeable)
179 ElfSectionFlags |= ELFSection::SHF_MERGE;
180 if (Flags & SectionFlags::TLS)
181 ElfSectionFlags |= ELFSection::SHF_TLS;
182 if (Flags & SectionFlags::Strings)
183 ElfSectionFlags |= ELFSection::SHF_STRINGS;
185 return ElfSectionFlags;
188 // For global symbols without a section, return the Null section as a
190 ELFSection &ELFWriter::getGlobalSymELFSection(const GlobalVariable *GV,
192 // If this is a declaration, the symbol does not have a section.
193 if (!GV->hasInitializer()) {
194 Sym.SectionIdx = ELFSection::SHN_UNDEF;
195 return getNullSection();
198 // Get the name and flags of the section for the global
199 const Section *S = TAI->SectionForGlobal(GV);
200 unsigned SectionType = ELFSection::SHT_PROGBITS;
201 unsigned SectionFlags = getElfSectionFlags(S->getFlags());
202 DOUT << "Section " << S->getName() << " for global " << GV->getName() << "\n";
204 const TargetData *TD = TM.getTargetData();
205 unsigned Align = TD->getPreferredAlignment(GV);
206 Constant *CV = GV->getInitializer();
208 // If this global has a zero initializer, go to .bss or common section.
209 // Variables are part of the common block if they are zero initialized
210 // and allowed to be merged with other symbols.
211 if (CV->isNullValue() || isa<UndefValue>(CV)) {
212 SectionType = ELFSection::SHT_NOBITS;
213 ELFSection &ElfS = getSection(S->getName(), SectionType, SectionFlags);
214 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
215 GV->hasCommonLinkage()) {
216 Sym.SectionIdx = ELFSection::SHN_COMMON;
222 Sym.SectionIdx = ElfS.SectionIdx;
223 if (Align) ElfS.Size = (ElfS.Size + Align-1) & ~(Align-1);
224 ElfS.Align = std::max(ElfS.Align, Align);
228 Sym.IsConstant = true;
229 ELFSection &ElfS = getSection(S->getName(), SectionType, SectionFlags);
230 Sym.SectionIdx = ElfS.SectionIdx;
231 ElfS.Align = std::max(ElfS.Align, Align);
235 void ELFWriter::EmitFunctionDeclaration(const Function *F) {
237 GblSym.setBind(ELFSym::STB_GLOBAL);
238 GblSym.setType(ELFSym::STT_NOTYPE);
239 GblSym.setVisibility(ELFSym::STV_DEFAULT);
240 GblSym.SectionIdx = ELFSection::SHN_UNDEF;
241 SymbolList.push_back(GblSym);
244 void ELFWriter::EmitGlobalVar(const GlobalVariable *GV) {
245 unsigned SymBind = getGlobalELFLinkage(GV);
246 unsigned Align=0, Size=0;
248 GblSym.setBind(SymBind);
249 GblSym.setVisibility(getGlobalELFVisibility(GV));
251 if (GV->hasInitializer()) {
252 GblSym.setType(ELFSym::STT_OBJECT);
253 const TargetData *TD = TM.getTargetData();
254 Align = TD->getPreferredAlignment(GV);
255 Size = TD->getTypeAllocSize(GV->getInitializer()->getType());
258 GblSym.setType(ELFSym::STT_NOTYPE);
261 ELFSection &GblSection = getGlobalSymELFSection(GV, GblSym);
263 if (GblSym.IsCommon) {
264 GblSym.Value = Align;
265 } else if (GblSym.IsBss) {
266 GblSym.Value = GblSection.Size;
267 GblSection.Size += Size;
268 } else if (GblSym.IsConstant){
269 // GblSym.Value should contain the symbol index inside the section,
270 // and all symbols should start on their required alignment boundary
271 GblSym.Value = (GblSection.size() + (Align-1)) & (-Align);
272 GblSection.emitAlignment(Align);
273 EmitGlobalConstant(GV->getInitializer(), GblSection);
276 // Local symbols should come first on the symbol table.
277 if (!GV->hasPrivateLinkage()) {
278 if (SymBind == ELFSym::STB_LOCAL)
279 SymbolList.push_front(GblSym);
281 SymbolList.push_back(GblSym);
285 void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
288 // Print the fields in successive locations. Pad to align if needed!
289 const TargetData *TD = TM.getTargetData();
290 unsigned Size = TD->getTypeAllocSize(CVS->getType());
291 const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
292 uint64_t sizeSoFar = 0;
293 for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
294 const Constant* field = CVS->getOperand(i);
296 // Check if padding is needed and insert one or more 0s.
297 uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
298 uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
299 - cvsLayout->getElementOffset(i)) - fieldSize;
300 sizeSoFar += fieldSize + padSize;
302 // Now print the actual field value.
303 EmitGlobalConstant(field, GblS);
305 // Insert padding - this may include padding to increase the size of the
306 // current field up to the ABI size (if the struct is not packed) as well
307 // as padding to ensure that the next field starts at the right offset.
308 for (unsigned p=0; p < padSize; p++)
311 assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
312 "Layout of constant struct may be incorrect!");
315 void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
316 const TargetData *TD = TM.getTargetData();
317 unsigned Size = TD->getTypeAllocSize(CV->getType());
319 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
320 if (CVA->isString()) {
321 std::string GblStr = CVA->getAsString();
322 GblStr.resize(GblStr.size()-1);
323 GblS.emitString(GblStr);
324 } else { // Not a string. Print the values in successive locations
325 for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
326 EmitGlobalConstant(CVA->getOperand(i), GblS);
329 } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
330 EmitGlobalConstantStruct(CVS, GblS);
332 } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
333 uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
334 if (CFP->getType() == Type::DoubleTy)
335 GblS.emitWord64(Val);
336 else if (CFP->getType() == Type::FloatTy)
337 GblS.emitWord32(Val);
338 else if (CFP->getType() == Type::X86_FP80Ty) {
339 assert(0 && "X86_FP80Ty global emission not implemented");
340 } else if (CFP->getType() == Type::PPC_FP128Ty)
341 assert(0 && "PPC_FP128Ty global emission not implemented");
343 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
345 GblS.emitWord32(CI->getZExtValue());
347 GblS.emitWord64(CI->getZExtValue());
349 assert(0 && "LargeInt global emission not implemented");
351 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
352 const VectorType *PTy = CP->getType();
353 for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
354 EmitGlobalConstant(CP->getOperand(I), GblS);
357 assert(0 && "unknown global constant");
361 bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
362 // Nothing to do here, this is all done through the MCE object above.
366 /// doFinalization - Now that the module has been completely processed, emit
367 /// the ELF file to 'O'.
368 bool ELFWriter::doFinalization(Module &M) {
369 /// FIXME: This should be removed when moving to ObjectCodeEmiter. Since the
370 /// current ELFCodeEmiter uses CurrBuff, ... it doesn't update S.Data
371 /// vector size for .text sections, so this is a quick dirty fix
372 ELFSection &TS = getTextSection();
374 BinaryData &BD = TS.getData();
375 for (unsigned e=0; e<TS.Size; ++e)
379 // Emit .data section placeholder
382 // Emit .bss section placeholder
385 // Build and emit data, bss and "common" sections.
386 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
392 // Emit all pending globals
393 // TODO: this should be done only for referenced symbols
394 for (SetVector<GlobalValue*>::const_iterator I = PendingGlobals.begin(),
395 E = PendingGlobals.end(); I != E; ++I) {
397 // No need to emit the symbol again
398 if (GblSymLookup.find(*I) != GblSymLookup.end())
401 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
403 } else if (Function *F = dyn_cast<Function>(*I)) {
404 // If function is not in GblSymLookup, it doesn't have a body,
405 // so emit the symbol as a function declaration (no section associated)
406 EmitFunctionDeclaration(F);
408 assert("unknown howto handle pending global");
410 GblSymLookup[*I] = 0;
413 // Emit non-executable stack note
414 if (TAI->getNonexecutableStackDirective())
415 getNonExecStackSection();
417 // Emit a symbol for each section created until now
418 for (std::map<std::string, ELFSection*>::iterator I = SectionLookup.begin(),
419 E = SectionLookup.end(); I != E; ++I) {
420 ELFSection *ES = I->second;
423 if (ES->SectionIdx == 0) continue;
425 ELFSym SectionSym(0);
426 SectionSym.SectionIdx = ES->SectionIdx;
428 SectionSym.setBind(ELFSym::STB_LOCAL);
429 SectionSym.setType(ELFSym::STT_SECTION);
430 SectionSym.setVisibility(ELFSym::STV_DEFAULT);
432 // Local symbols go in the list front
433 SymbolList.push_front(SectionSym);
439 // Emit the symbol table now, if non-empty.
442 // Emit the relocation sections.
445 // Emit the sections string table.
446 EmitSectionTableStringTable();
448 // Dump the sections and section table to the .o file.
449 OutputSectionsAndSectionTable();
451 // We are done with the abstract symbols.
455 // Release the name mangler object.
456 delete Mang; Mang = 0;
460 /// EmitRelocations - Emit relocations
461 void ELFWriter::EmitRelocations() {
463 // Create Relocation sections for each section which needs it.
464 for (std::list<ELFSection>::iterator I = SectionList.begin(),
465 E = SectionList.end(); I != E; ++I) {
467 // This section does not have relocations
468 if (!I->hasRelocations()) continue;
470 // Get the relocation section for section 'I'
471 bool HasRelA = TEW->hasRelocationAddend();
472 ELFSection &RelSec = getRelocSection(I->getName(), HasRelA,
473 TEW->getPrefELFAlignment());
475 // 'Link' - Section hdr idx of the associated symbol table
476 // 'Info' - Section hdr idx of the section to which the relocation applies
477 ELFSection &SymTab = getSymbolTableSection();
478 RelSec.Link = SymTab.SectionIdx;
479 RelSec.Info = I->SectionIdx;
480 RelSec.EntSize = TEW->getRelocationEntrySize();
482 // Get the relocations from Section
483 std::vector<MachineRelocation> Relos = I->getRelocations();
484 for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
485 MRE = Relos.end(); MRI != MRE; ++MRI) {
486 MachineRelocation &MR = *MRI;
488 // Offset from the start of the section containing the symbol
489 unsigned Offset = MR.getMachineCodeOffset();
491 // Symbol index in the symbol table
494 // Target specific ELF relocation type
495 unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
497 // Constant addend used to compute the value to be stored
498 // into the relocatable field
501 // There are several machine relocations types, and each one of
502 // them needs a different approach to retrieve the symbol table index.
503 if (MR.isGlobalValue()) {
504 const GlobalValue *G = MR.getGlobalValue();
505 SymIdx = GblSymLookup[G];
506 Addend = TEW->getAddendForRelTy(RelType);
508 unsigned SectionIdx = MR.getConstantVal();
509 // TODO: use a map for this.
510 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
511 E = SymbolList.end(); I != E; ++I)
512 if ((SectionIdx == I->SectionIdx) &&
513 (I->getType() == ELFSym::STT_SECTION)) {
514 SymIdx = I->SymTabIdx;
517 Addend = (uint64_t)MR.getResultPointer();
520 // Get the relocation entry and emit to the relocation section
521 ELFRelocation Rel(Offset, SymIdx, RelType, HasRelA, Addend);
522 EmitRelocation(RelSec, Rel, HasRelA);
527 /// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
528 void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
530 RelSec.emitWord(Rel.getOffset());
531 RelSec.emitWord(Rel.getInfo(is64Bit));
533 RelSec.emitWord(Rel.getAddend());
536 /// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
537 void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
539 SymbolTable.emitWord32(Sym.NameIdx);
540 SymbolTable.emitByte(Sym.Info);
541 SymbolTable.emitByte(Sym.Other);
542 SymbolTable.emitWord16(Sym.SectionIdx);
543 SymbolTable.emitWord64(Sym.Value);
544 SymbolTable.emitWord64(Sym.Size);
546 SymbolTable.emitWord32(Sym.NameIdx);
547 SymbolTable.emitWord32(Sym.Value);
548 SymbolTable.emitWord32(Sym.Size);
549 SymbolTable.emitByte(Sym.Info);
550 SymbolTable.emitByte(Sym.Other);
551 SymbolTable.emitWord16(Sym.SectionIdx);
555 /// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
556 /// Section Header Table
557 void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
558 const ELFSection &SHdr) {
559 SHdrTab.emitWord32(SHdr.NameIdx);
560 SHdrTab.emitWord32(SHdr.Type);
562 SHdrTab.emitWord64(SHdr.Flags);
563 SHdrTab.emitWord(SHdr.Addr);
564 SHdrTab.emitWord(SHdr.Offset);
565 SHdrTab.emitWord64(SHdr.Size);
566 SHdrTab.emitWord32(SHdr.Link);
567 SHdrTab.emitWord32(SHdr.Info);
568 SHdrTab.emitWord64(SHdr.Align);
569 SHdrTab.emitWord64(SHdr.EntSize);
571 SHdrTab.emitWord32(SHdr.Flags);
572 SHdrTab.emitWord(SHdr.Addr);
573 SHdrTab.emitWord(SHdr.Offset);
574 SHdrTab.emitWord32(SHdr.Size);
575 SHdrTab.emitWord32(SHdr.Link);
576 SHdrTab.emitWord32(SHdr.Info);
577 SHdrTab.emitWord32(SHdr.Align);
578 SHdrTab.emitWord32(SHdr.EntSize);
582 /// EmitStringTable - If the current symbol table is non-empty, emit the string
584 void ELFWriter::EmitStringTable() {
585 if (!SymbolList.size()) return; // Empty symbol table.
586 ELFSection &StrTab = getStringTableSection();
588 // Set the zero'th symbol to a null byte, as required.
591 // Walk on the symbol list and write symbol names into the
594 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
595 E = SymbolList.end(); I != E; ++I) {
597 // Use the name mangler to uniquify the LLVM symbol.
599 if (I->GV) Name.append(Mang->getValueName(I->GV));
605 StrTab.emitString(Name);
607 // Keep track of the number of bytes emitted to this section.
608 Index += Name.size()+1;
611 assert(Index == StrTab.size());
615 /// EmitSymbolTable - Emit the symbol table itself.
616 void ELFWriter::EmitSymbolTable() {
617 if (!SymbolList.size()) return; // Empty symbol table.
619 unsigned FirstNonLocalSymbol = 1;
620 // Now that we have emitted the string table and know the offset into the
621 // string table of each symbol, emit the symbol table itself.
622 ELFSection &SymTab = getSymbolTableSection();
623 SymTab.Align = TEW->getPrefELFAlignment();
625 // Section Index of .strtab.
626 SymTab.Link = getStringTableSection().SectionIdx;
628 // Size of each symtab entry.
629 SymTab.EntSize = TEW->getSymTabEntrySize();
631 // The first entry in the symtab is the null symbol
632 ELFSym NullSym = ELFSym(0);
633 EmitSymbol(SymTab, NullSym);
635 // Emit all the symbols to the symbol table. Skip the null
636 // symbol, cause it's emitted already
638 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
639 E = SymbolList.end(); I != E; ++I, ++Index) {
640 // Keep track of the first non-local symbol
641 if (I->getBind() == ELFSym::STB_LOCAL)
642 FirstNonLocalSymbol++;
644 // Emit symbol to the symbol table
645 EmitSymbol(SymTab, *I);
647 // Record the symbol table index for each global value
649 GblSymLookup[I->GV] = Index;
651 // Keep track on the symbol index into the symbol table
652 I->SymTabIdx = Index;
655 SymTab.Info = FirstNonLocalSymbol;
656 SymTab.Size = SymTab.size();
659 /// EmitSectionTableStringTable - This method adds and emits a section for the
660 /// ELF Section Table string table: the string table that holds all of the
662 void ELFWriter::EmitSectionTableStringTable() {
663 // First step: add the section for the string table to the list of sections:
664 ELFSection &SHStrTab = getSectionHeaderStringTableSection();
666 // Now that we know which section number is the .shstrtab section, update the
667 // e_shstrndx entry in the ELF header.
668 ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
670 // Set the NameIdx of each section in the string table and emit the bytes for
674 for (std::list<ELFSection>::iterator I = SectionList.begin(),
675 E = SectionList.end(); I != E; ++I) {
676 // Set the index into the table. Note if we have lots of entries with
677 // common suffixes, we could memoize them here if we cared.
679 SHStrTab.emitString(I->getName());
681 // Keep track of the number of bytes emitted to this section.
682 Index += I->getName().size()+1;
685 // Set the size of .shstrtab now that we know what it is.
686 assert(Index == SHStrTab.size());
687 SHStrTab.Size = Index;
690 /// OutputSectionsAndSectionTable - Now that we have constructed the file header
691 /// and all of the sections, emit these to the ostream destination and emit the
693 void ELFWriter::OutputSectionsAndSectionTable() {
694 // Pass #1: Compute the file offset for each section.
695 size_t FileOff = ElfHdr.size(); // File header first.
697 // Adjust alignment of all section if needed.
698 for (std::list<ELFSection>::iterator I = SectionList.begin(),
699 E = SectionList.end(); I != E; ++I) {
701 // Section idx 0 has 0 offset
710 // Update Section size
714 // Align FileOff to whatever the alignment restrictions of the section are.
716 FileOff = (FileOff+I->Align-1) & ~(I->Align-1);
722 // Align Section Header.
723 unsigned TableAlign = TEW->getPrefELFAlignment();
724 FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
726 // Now that we know where all of the sections will be emitted, set the e_shnum
727 // entry in the ELF header.
728 ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
730 // Now that we know the offset in the file of the section table, update the
731 // e_shoff address in the ELF header.
732 ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
734 // Now that we know all of the data in the file header, emit it and all of the
736 O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
737 FileOff = ElfHdr.size();
739 // Section Header Table blob
740 BinaryObject SHdrTable(isLittleEndian, is64Bit);
742 // Emit all of sections to the file and build the section header table.
743 while (!SectionList.empty()) {
744 ELFSection &S = *SectionList.begin();
745 DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
746 << ", Size: " << S.Size << ", Offset: " << S.Offset
747 << ", SectionData Size: " << S.size() << "\n";
749 // Align FileOff to whatever the alignment restrictions of the section are.
752 for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
753 FileOff != NewFileOff; ++FileOff)
756 O.write((char *)&S.getData()[0], S.Size);
760 EmitSectionHeader(SHdrTable, S);
761 SectionList.pop_front();
764 // Align output for the section table.
765 for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
766 FileOff != NewFileOff; ++FileOff)
769 // Emit the section table itself.
770 O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());