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"
33 #include "ELFWriter.h"
34 #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/CodeGen/MachineFunctionPass.h"
45 #include "llvm/Target/TargetData.h"
46 #include "llvm/Target/TargetMachine.h"
47 #include "llvm/Support/Mangler.h"
48 #include "llvm/Support/Streams.h"
49 #include "llvm/Support/raw_ostream.h"
50 #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::getGlobalELFLinkage(const GlobalVariable *GV) {
145 if (GV->hasInternalLinkage())
146 return ELFSym::STB_LOCAL;
148 if (GV->hasWeakLinkage())
149 return ELFSym::STB_WEAK;
151 return ELFSym::STB_GLOBAL;
154 // For global symbols without a section, return the Null section as a
156 ELFSection &ELFWriter::getGlobalSymELFSection(const GlobalVariable *GV,
158 const Section *S = TAI->SectionForGlobal(GV);
159 unsigned Flags = S->getFlags();
160 unsigned SectionType = ELFSection::SHT_PROGBITS;
161 unsigned SHdrFlags = ELFSection::SHF_ALLOC;
162 DOUT << "Section " << S->getName() << " for global " << GV->getName() << "\n";
164 // If this is an external global, the symbol does not have a section.
165 if (!GV->hasInitializer()) {
166 Sym.SectionIdx = ELFSection::SHN_UNDEF;
167 return getNullSection();
170 const TargetData *TD = TM.getTargetData();
171 unsigned Align = TD->getPreferredAlignment(GV);
172 Constant *CV = GV->getInitializer();
174 if (Flags & SectionFlags::Code)
175 SHdrFlags |= ELFSection::SHF_EXECINSTR;
176 if (Flags & SectionFlags::Writeable)
177 SHdrFlags |= ELFSection::SHF_WRITE;
178 if (Flags & SectionFlags::Mergeable)
179 SHdrFlags |= ELFSection::SHF_MERGE;
180 if (Flags & SectionFlags::TLS)
181 SHdrFlags |= ELFSection::SHF_TLS;
182 if (Flags & SectionFlags::Strings)
183 SHdrFlags |= ELFSection::SHF_STRINGS;
185 // If this global has a zero initializer, go to .bss or common section.
186 // Variables are part of the common block if they are zero initialized
187 // and allowed to be merged with other symbols.
188 if (CV->isNullValue() || isa<UndefValue>(CV)) {
189 SectionType = ELFSection::SHT_NOBITS;
190 ELFSection &ElfS = getSection(S->getName(), SectionType, SHdrFlags);
191 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
192 GV->hasCommonLinkage()) {
193 Sym.SectionIdx = ELFSection::SHN_COMMON;
199 Sym.SectionIdx = ElfS.SectionIdx;
200 if (Align) ElfS.Size = (ElfS.Size + Align-1) & ~(Align-1);
201 ElfS.Align = std::max(ElfS.Align, Align);
205 Sym.IsConstant = true;
206 ELFSection &ElfS = getSection(S->getName(), SectionType, SHdrFlags);
207 Sym.SectionIdx = ElfS.SectionIdx;
208 ElfS.Align = std::max(ElfS.Align, Align);
212 void ELFWriter::EmitFunctionDeclaration(const Function *F) {
214 GblSym.setBind(ELFSym::STB_GLOBAL);
215 GblSym.setType(ELFSym::STT_NOTYPE);
216 GblSym.SectionIdx = ELFSection::SHN_UNDEF;
217 SymbolList.push_back(GblSym);
220 void ELFWriter::EmitGlobalVar(const GlobalVariable *GV) {
221 unsigned SymBind = getGlobalELFLinkage(GV);
222 unsigned Align=0, Size=0;
224 GblSym.setBind(SymBind);
226 if (GV->hasInitializer()) {
227 GblSym.setType(ELFSym::STT_OBJECT);
228 const TargetData *TD = TM.getTargetData();
229 Align = TD->getPreferredAlignment(GV);
230 Size = TD->getTypeAllocSize(GV->getInitializer()->getType());
233 GblSym.setType(ELFSym::STT_NOTYPE);
236 ELFSection &GblSection = getGlobalSymELFSection(GV, GblSym);
238 if (GblSym.IsCommon) {
239 GblSym.Value = Align;
240 } else if (GblSym.IsBss) {
241 GblSym.Value = GblSection.Size;
242 GblSection.Size += Size;
243 } else if (GblSym.IsConstant){
244 // GblSym.Value should contain the symbol index inside the section,
245 // and all symbols should start on their required alignment boundary
246 GblSym.Value = (GblSection.size() + (Align-1)) & (-Align);
247 GblSection.emitAlignment(Align);
248 EmitGlobalConstant(GV->getInitializer(), GblSection);
251 // Local symbols should come first on the symbol table.
252 if (!GV->hasPrivateLinkage()) {
253 if (SymBind == ELFSym::STB_LOCAL)
254 SymbolList.push_front(GblSym);
256 SymbolList.push_back(GblSym);
260 void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
263 // Print the fields in successive locations. Pad to align if needed!
264 const TargetData *TD = TM.getTargetData();
265 unsigned Size = TD->getTypeAllocSize(CVS->getType());
266 const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
267 uint64_t sizeSoFar = 0;
268 for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
269 const Constant* field = CVS->getOperand(i);
271 // Check if padding is needed and insert one or more 0s.
272 uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
273 uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
274 - cvsLayout->getElementOffset(i)) - fieldSize;
275 sizeSoFar += fieldSize + padSize;
277 // Now print the actual field value.
278 EmitGlobalConstant(field, GblS);
280 // Insert padding - this may include padding to increase the size of the
281 // current field up to the ABI size (if the struct is not packed) as well
282 // as padding to ensure that the next field starts at the right offset.
283 for (unsigned p=0; p < padSize; p++)
286 assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
287 "Layout of constant struct may be incorrect!");
290 void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
291 const TargetData *TD = TM.getTargetData();
292 unsigned Size = TD->getTypeAllocSize(CV->getType());
294 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
295 if (CVA->isString()) {
296 std::string GblStr = CVA->getAsString();
297 GblStr.resize(GblStr.size()-1);
298 GblS.emitString(GblStr);
299 } else { // Not a string. Print the values in successive locations
300 for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
301 EmitGlobalConstant(CVA->getOperand(i), GblS);
304 } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
305 EmitGlobalConstantStruct(CVS, GblS);
307 } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
308 uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
309 if (CFP->getType() == Type::DoubleTy)
310 GblS.emitWord64(Val);
311 else if (CFP->getType() == Type::FloatTy)
312 GblS.emitWord32(Val);
313 else if (CFP->getType() == Type::X86_FP80Ty) {
314 assert(0 && "X86_FP80Ty global emission not implemented");
315 } else if (CFP->getType() == Type::PPC_FP128Ty)
316 assert(0 && "PPC_FP128Ty global emission not implemented");
318 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
320 GblS.emitWord32(CI->getZExtValue());
322 GblS.emitWord64(CI->getZExtValue());
324 assert(0 && "LargeInt global emission not implemented");
326 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
327 const VectorType *PTy = CP->getType();
328 for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
329 EmitGlobalConstant(CP->getOperand(I), GblS);
332 assert(0 && "unknown global constant");
336 bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
337 // Nothing to do here, this is all done through the MCE object above.
341 /// doFinalization - Now that the module has been completely processed, emit
342 /// the ELF file to 'O'.
343 bool ELFWriter::doFinalization(Module &M) {
344 /// FIXME: This should be removed when moving to ObjectCodeEmiter. Since the
345 /// current ELFCodeEmiter uses CurrBuff, ... it doesn't update S.Data
346 /// vector size for .text sections, so this is a quick dirty fix
347 ELFSection &TS = getTextSection();
349 BinaryData &BD = TS.getData();
350 for (unsigned e=0; e<TS.Size; ++e)
354 // Emit .data section placeholder
357 // Emit .bss section placeholder
360 // Build and emit data, bss and "common" sections.
361 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
367 // Emit all pending globals
368 // TODO: this should be done only for referenced symbols
369 for (SetVector<GlobalValue*>::const_iterator I = PendingGlobals.begin(),
370 E = PendingGlobals.end(); I != E; ++I) {
372 // No need to emit the symbol again
373 if (GblSymLookup.find(*I) != GblSymLookup.end())
376 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
378 } else if (Function *F = dyn_cast<Function>(*I)) {
379 // If function is not in GblSymLookup, it doesn't have a body,
380 // so emit the symbol as a function declaration (no section associated)
381 EmitFunctionDeclaration(F);
383 assert("unknown howto handle pending global");
385 GblSymLookup[*I] = 0;
388 // Emit non-executable stack note
389 if (TAI->getNonexecutableStackDirective())
390 getNonExecStackSection();
392 // Emit a symbol for each section created until now
393 for (std::map<std::string, ELFSection*>::iterator I = SectionLookup.begin(),
394 E = SectionLookup.end(); I != E; ++I) {
395 ELFSection *ES = I->second;
398 if (ES->SectionIdx == 0) continue;
400 ELFSym SectionSym(0);
401 SectionSym.SectionIdx = ES->SectionIdx;
403 SectionSym.setBind(ELFSym::STB_LOCAL);
404 SectionSym.setType(ELFSym::STT_SECTION);
406 // Local symbols go in the list front
407 SymbolList.push_front(SectionSym);
413 // Emit the symbol table now, if non-empty.
416 // Emit the relocation sections.
419 // Emit the sections string table.
420 EmitSectionTableStringTable();
422 // Dump the sections and section table to the .o file.
423 OutputSectionsAndSectionTable();
425 // We are done with the abstract symbols.
429 // Release the name mangler object.
430 delete Mang; Mang = 0;
434 /// EmitRelocations - Emit relocations
435 void ELFWriter::EmitRelocations() {
437 // Create Relocation sections for each section which needs it.
438 for (std::list<ELFSection>::iterator I = SectionList.begin(),
439 E = SectionList.end(); I != E; ++I) {
441 // This section does not have relocations
442 if (!I->hasRelocations()) continue;
444 // Get the relocation section for section 'I'
445 bool HasRelA = TEW->hasRelocationAddend();
446 ELFSection &RelSec = getRelocSection(I->getName(), HasRelA);
448 // 'Link' - Section hdr idx of the associated symbol table
449 // 'Info' - Section hdr idx of the section to which the relocation applies
450 ELFSection &SymTab = getSymbolTableSection();
451 RelSec.Link = SymTab.SectionIdx;
452 RelSec.Info = I->SectionIdx;
453 RelSec.EntSize = TEW->getRelocationEntrySize();
455 // Get the relocations from Section
456 std::vector<MachineRelocation> Relos = I->getRelocations();
457 for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
458 MRE = Relos.end(); MRI != MRE; ++MRI) {
459 MachineRelocation &MR = *MRI;
461 // Offset from the start of the section containing the symbol
462 unsigned Offset = MR.getMachineCodeOffset();
464 // Symbol index in the symbol table
467 // Target specific ELF relocation type
468 unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
470 // Constant addend used to compute the value to be stored
471 // into the relocatable field
474 // There are several machine relocations types, and each one of
475 // them needs a different approach to retrieve the symbol table index.
476 if (MR.isGlobalValue()) {
477 const GlobalValue *G = MR.getGlobalValue();
478 SymIdx = GblSymLookup[G];
479 Addend = TEW->getAddendForRelTy(RelType);
481 unsigned SectionIdx = MR.getConstantVal();
482 // TODO: use a map for this.
483 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
484 E = SymbolList.end(); I != E; ++I)
485 if ((SectionIdx == I->SectionIdx) &&
486 (I->getType() == ELFSym::STT_SECTION)) {
487 SymIdx = I->SymTabIdx;
490 Addend = (uint64_t)MR.getResultPointer();
493 // Get the relocation entry and emit to the relocation section
494 ELFRelocation Rel(Offset, SymIdx, RelType, HasRelA, Addend);
495 EmitRelocation(RelSec, Rel, HasRelA);
500 /// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
501 void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
503 RelSec.emitWord(Rel.getOffset());
504 RelSec.emitWord(Rel.getInfo(is64Bit));
506 RelSec.emitWord(Rel.getAddend());
509 /// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
510 void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
512 SymbolTable.emitWord32(Sym.NameIdx);
513 SymbolTable.emitByte(Sym.Info);
514 SymbolTable.emitByte(Sym.Other);
515 SymbolTable.emitWord16(Sym.SectionIdx);
516 SymbolTable.emitWord64(Sym.Value);
517 SymbolTable.emitWord64(Sym.Size);
519 SymbolTable.emitWord32(Sym.NameIdx);
520 SymbolTable.emitWord32(Sym.Value);
521 SymbolTable.emitWord32(Sym.Size);
522 SymbolTable.emitByte(Sym.Info);
523 SymbolTable.emitByte(Sym.Other);
524 SymbolTable.emitWord16(Sym.SectionIdx);
528 /// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
529 /// Section Header Table
530 void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
531 const ELFSection &SHdr) {
532 SHdrTab.emitWord32(SHdr.NameIdx);
533 SHdrTab.emitWord32(SHdr.Type);
535 SHdrTab.emitWord64(SHdr.Flags);
536 SHdrTab.emitWord(SHdr.Addr);
537 SHdrTab.emitWord(SHdr.Offset);
538 SHdrTab.emitWord64(SHdr.Size);
539 SHdrTab.emitWord32(SHdr.Link);
540 SHdrTab.emitWord32(SHdr.Info);
541 SHdrTab.emitWord64(SHdr.Align);
542 SHdrTab.emitWord64(SHdr.EntSize);
544 SHdrTab.emitWord32(SHdr.Flags);
545 SHdrTab.emitWord(SHdr.Addr);
546 SHdrTab.emitWord(SHdr.Offset);
547 SHdrTab.emitWord32(SHdr.Size);
548 SHdrTab.emitWord32(SHdr.Link);
549 SHdrTab.emitWord32(SHdr.Info);
550 SHdrTab.emitWord32(SHdr.Align);
551 SHdrTab.emitWord32(SHdr.EntSize);
555 /// EmitStringTable - If the current symbol table is non-empty, emit the string
557 void ELFWriter::EmitStringTable() {
558 if (!SymbolList.size()) return; // Empty symbol table.
559 ELFSection &StrTab = getStringTableSection();
561 // Set the zero'th symbol to a null byte, as required.
564 // Walk on the symbol list and write symbol names into the
567 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
568 E = SymbolList.end(); I != E; ++I) {
570 // Use the name mangler to uniquify the LLVM symbol.
572 if (I->GV) Name.append(Mang->getValueName(I->GV));
578 StrTab.emitString(Name);
580 // Keep track of the number of bytes emitted to this section.
581 Index += Name.size()+1;
584 assert(Index == StrTab.size());
588 /// EmitSymbolTable - Emit the symbol table itself.
589 void ELFWriter::EmitSymbolTable() {
590 if (!SymbolList.size()) return; // Empty symbol table.
592 unsigned FirstNonLocalSymbol = 1;
593 // Now that we have emitted the string table and know the offset into the
594 // string table of each symbol, emit the symbol table itself.
595 ELFSection &SymTab = getSymbolTableSection();
596 SymTab.Align = TEW->getPrefELFAlignment();
598 // Section Index of .strtab.
599 SymTab.Link = getStringTableSection().SectionIdx;
601 // Size of each symtab entry.
602 SymTab.EntSize = TEW->getSymTabEntrySize();
604 // The first entry in the symtab is the null symbol
605 ELFSym NullSym = ELFSym(0);
606 EmitSymbol(SymTab, NullSym);
608 // Emit all the symbols to the symbol table. Skip the null
609 // symbol, cause it's emitted already
611 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
612 E = SymbolList.end(); I != E; ++I, ++Index) {
613 // Keep track of the first non-local symbol
614 if (I->getBind() == ELFSym::STB_LOCAL)
615 FirstNonLocalSymbol++;
617 // Emit symbol to the symbol table
618 EmitSymbol(SymTab, *I);
620 // Record the symbol table index for each global value
622 GblSymLookup[I->GV] = Index;
624 // Keep track on the symbol index into the symbol table
625 I->SymTabIdx = Index;
628 SymTab.Info = FirstNonLocalSymbol;
629 SymTab.Size = SymTab.size();
632 /// EmitSectionTableStringTable - This method adds and emits a section for the
633 /// ELF Section Table string table: the string table that holds all of the
635 void ELFWriter::EmitSectionTableStringTable() {
636 // First step: add the section for the string table to the list of sections:
637 ELFSection &SHStrTab = getSectionHeaderStringTableSection();
639 // Now that we know which section number is the .shstrtab section, update the
640 // e_shstrndx entry in the ELF header.
641 ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
643 // Set the NameIdx of each section in the string table and emit the bytes for
647 for (std::list<ELFSection>::iterator I = SectionList.begin(),
648 E = SectionList.end(); I != E; ++I) {
649 // Set the index into the table. Note if we have lots of entries with
650 // common suffixes, we could memoize them here if we cared.
652 SHStrTab.emitString(I->getName());
654 // Keep track of the number of bytes emitted to this section.
655 Index += I->getName().size()+1;
658 // Set the size of .shstrtab now that we know what it is.
659 assert(Index == SHStrTab.size());
660 SHStrTab.Size = Index;
663 /// OutputSectionsAndSectionTable - Now that we have constructed the file header
664 /// and all of the sections, emit these to the ostream destination and emit the
666 void ELFWriter::OutputSectionsAndSectionTable() {
667 // Pass #1: Compute the file offset for each section.
668 size_t FileOff = ElfHdr.size(); // File header first.
670 // Adjust alignment of all section if needed.
671 for (std::list<ELFSection>::iterator I = SectionList.begin(),
672 E = SectionList.end(); I != E; ++I) {
674 // Section idx 0 has 0 offset
683 // Update Section size
687 // Align FileOff to whatever the alignment restrictions of the section are.
689 FileOff = (FileOff+I->Align-1) & ~(I->Align-1);
695 // Align Section Header.
696 unsigned TableAlign = TEW->getPrefELFAlignment();
697 FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
699 // Now that we know where all of the sections will be emitted, set the e_shnum
700 // entry in the ELF header.
701 ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
703 // Now that we know the offset in the file of the section table, update the
704 // e_shoff address in the ELF header.
705 ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
707 // Now that we know all of the data in the file header, emit it and all of the
709 O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
710 FileOff = ElfHdr.size();
712 // Section Header Table blob
713 BinaryObject SHdrTable(isLittleEndian, is64Bit);
715 // Emit all of sections to the file and build the section header table.
716 while (!SectionList.empty()) {
717 ELFSection &S = *SectionList.begin();
718 DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
719 << ", Size: " << S.Size << ", Offset: " << S.Offset
720 << ", SectionData Size: " << S.size() << "\n";
722 // Align FileOff to whatever the alignment restrictions of the section are.
725 for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
726 FileOff != NewFileOff; ++FileOff)
729 O.write((char *)&S.getData()[0], S.Size);
733 EmitSectionHeader(SHdrTable, S);
734 SectionList.pop_front();
737 // Align output for the section table.
738 for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
739 FileOff != NewFileOff; ++FileOff)
742 // Emit the section table itself.
743 O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());