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 // For global symbols without a section, return the Null section as a
171 ELFSection &ELFWriter::getGlobalSymELFSection(const GlobalVariable *GV,
173 const Section *S = TAI->SectionForGlobal(GV);
174 unsigned Flags = S->getFlags();
175 unsigned SectionType = ELFSection::SHT_PROGBITS;
176 unsigned SHdrFlags = ELFSection::SHF_ALLOC;
177 DOUT << "Section " << S->getName() << " for global " << GV->getName() << "\n";
179 // If this is an external global, the symbol does not have a section.
180 if (!GV->hasInitializer()) {
181 Sym.SectionIdx = ELFSection::SHN_UNDEF;
182 return getNullSection();
185 const TargetData *TD = TM.getTargetData();
186 unsigned Align = TD->getPreferredAlignment(GV);
187 Constant *CV = GV->getInitializer();
189 if (Flags & SectionFlags::Code)
190 SHdrFlags |= ELFSection::SHF_EXECINSTR;
191 if (Flags & SectionFlags::Writeable)
192 SHdrFlags |= ELFSection::SHF_WRITE;
193 if (Flags & SectionFlags::Mergeable)
194 SHdrFlags |= ELFSection::SHF_MERGE;
195 if (Flags & SectionFlags::TLS)
196 SHdrFlags |= ELFSection::SHF_TLS;
197 if (Flags & SectionFlags::Strings)
198 SHdrFlags |= ELFSection::SHF_STRINGS;
200 // If this global has a zero initializer, go to .bss or common section.
201 // Variables are part of the common block if they are zero initialized
202 // and allowed to be merged with other symbols.
203 if (CV->isNullValue() || isa<UndefValue>(CV)) {
204 SectionType = ELFSection::SHT_NOBITS;
205 ELFSection &ElfS = getSection(S->getName(), SectionType, SHdrFlags);
206 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
207 GV->hasCommonLinkage()) {
208 Sym.SectionIdx = ELFSection::SHN_COMMON;
214 Sym.SectionIdx = ElfS.SectionIdx;
215 if (Align) ElfS.Size = (ElfS.Size + Align-1) & ~(Align-1);
216 ElfS.Align = std::max(ElfS.Align, Align);
220 Sym.IsConstant = true;
221 ELFSection &ElfS = getSection(S->getName(), SectionType, SHdrFlags);
222 Sym.SectionIdx = ElfS.SectionIdx;
223 ElfS.Align = std::max(ElfS.Align, Align);
227 void ELFWriter::EmitFunctionDeclaration(const Function *F) {
229 GblSym.setBind(ELFSym::STB_GLOBAL);
230 GblSym.setType(ELFSym::STT_NOTYPE);
231 GblSym.setVisibility(ELFSym::STV_DEFAULT);
232 GblSym.SectionIdx = ELFSection::SHN_UNDEF;
233 SymbolList.push_back(GblSym);
236 void ELFWriter::EmitGlobalVar(const GlobalVariable *GV) {
237 unsigned SymBind = getGlobalELFLinkage(GV);
238 unsigned Align=0, Size=0;
240 GblSym.setBind(SymBind);
241 GblSym.setVisibility(getGlobalELFVisibility(GV));
243 if (GV->hasInitializer()) {
244 GblSym.setType(ELFSym::STT_OBJECT);
245 const TargetData *TD = TM.getTargetData();
246 Align = TD->getPreferredAlignment(GV);
247 Size = TD->getTypeAllocSize(GV->getInitializer()->getType());
250 GblSym.setType(ELFSym::STT_NOTYPE);
253 ELFSection &GblSection = getGlobalSymELFSection(GV, GblSym);
255 if (GblSym.IsCommon) {
256 GblSym.Value = Align;
257 } else if (GblSym.IsBss) {
258 GblSym.Value = GblSection.Size;
259 GblSection.Size += Size;
260 } else if (GblSym.IsConstant){
261 // GblSym.Value should contain the symbol index inside the section,
262 // and all symbols should start on their required alignment boundary
263 GblSym.Value = (GblSection.size() + (Align-1)) & (-Align);
264 GblSection.emitAlignment(Align);
265 EmitGlobalConstant(GV->getInitializer(), GblSection);
268 // Local symbols should come first on the symbol table.
269 if (!GV->hasPrivateLinkage()) {
270 if (SymBind == ELFSym::STB_LOCAL)
271 SymbolList.push_front(GblSym);
273 SymbolList.push_back(GblSym);
277 void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
280 // Print the fields in successive locations. Pad to align if needed!
281 const TargetData *TD = TM.getTargetData();
282 unsigned Size = TD->getTypeAllocSize(CVS->getType());
283 const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
284 uint64_t sizeSoFar = 0;
285 for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
286 const Constant* field = CVS->getOperand(i);
288 // Check if padding is needed and insert one or more 0s.
289 uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
290 uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
291 - cvsLayout->getElementOffset(i)) - fieldSize;
292 sizeSoFar += fieldSize + padSize;
294 // Now print the actual field value.
295 EmitGlobalConstant(field, GblS);
297 // Insert padding - this may include padding to increase the size of the
298 // current field up to the ABI size (if the struct is not packed) as well
299 // as padding to ensure that the next field starts at the right offset.
300 for (unsigned p=0; p < padSize; p++)
303 assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
304 "Layout of constant struct may be incorrect!");
307 void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
308 const TargetData *TD = TM.getTargetData();
309 unsigned Size = TD->getTypeAllocSize(CV->getType());
311 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
312 if (CVA->isString()) {
313 std::string GblStr = CVA->getAsString();
314 GblStr.resize(GblStr.size()-1);
315 GblS.emitString(GblStr);
316 } else { // Not a string. Print the values in successive locations
317 for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
318 EmitGlobalConstant(CVA->getOperand(i), GblS);
321 } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
322 EmitGlobalConstantStruct(CVS, GblS);
324 } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
325 uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
326 if (CFP->getType() == Type::DoubleTy)
327 GblS.emitWord64(Val);
328 else if (CFP->getType() == Type::FloatTy)
329 GblS.emitWord32(Val);
330 else if (CFP->getType() == Type::X86_FP80Ty) {
331 assert(0 && "X86_FP80Ty global emission not implemented");
332 } else if (CFP->getType() == Type::PPC_FP128Ty)
333 assert(0 && "PPC_FP128Ty global emission not implemented");
335 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
337 GblS.emitWord32(CI->getZExtValue());
339 GblS.emitWord64(CI->getZExtValue());
341 assert(0 && "LargeInt global emission not implemented");
343 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
344 const VectorType *PTy = CP->getType();
345 for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
346 EmitGlobalConstant(CP->getOperand(I), GblS);
349 assert(0 && "unknown global constant");
353 bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
354 // Nothing to do here, this is all done through the MCE object above.
358 /// doFinalization - Now that the module has been completely processed, emit
359 /// the ELF file to 'O'.
360 bool ELFWriter::doFinalization(Module &M) {
361 /// FIXME: This should be removed when moving to ObjectCodeEmiter. Since the
362 /// current ELFCodeEmiter uses CurrBuff, ... it doesn't update S.Data
363 /// vector size for .text sections, so this is a quick dirty fix
364 ELFSection &TS = getTextSection();
366 BinaryData &BD = TS.getData();
367 for (unsigned e=0; e<TS.Size; ++e)
371 // Emit .data section placeholder
374 // Emit .bss section placeholder
377 // Build and emit data, bss and "common" sections.
378 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
384 // Emit all pending globals
385 // TODO: this should be done only for referenced symbols
386 for (SetVector<GlobalValue*>::const_iterator I = PendingGlobals.begin(),
387 E = PendingGlobals.end(); I != E; ++I) {
389 // No need to emit the symbol again
390 if (GblSymLookup.find(*I) != GblSymLookup.end())
393 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
395 } else if (Function *F = dyn_cast<Function>(*I)) {
396 // If function is not in GblSymLookup, it doesn't have a body,
397 // so emit the symbol as a function declaration (no section associated)
398 EmitFunctionDeclaration(F);
400 assert("unknown howto handle pending global");
402 GblSymLookup[*I] = 0;
405 // Emit non-executable stack note
406 if (TAI->getNonexecutableStackDirective())
407 getNonExecStackSection();
409 // Emit a symbol for each section created until now
410 for (std::map<std::string, ELFSection*>::iterator I = SectionLookup.begin(),
411 E = SectionLookup.end(); I != E; ++I) {
412 ELFSection *ES = I->second;
415 if (ES->SectionIdx == 0) continue;
417 ELFSym SectionSym(0);
418 SectionSym.SectionIdx = ES->SectionIdx;
420 SectionSym.setBind(ELFSym::STB_LOCAL);
421 SectionSym.setType(ELFSym::STT_SECTION);
422 SectionSym.setVisibility(ELFSym::STV_DEFAULT);
424 // Local symbols go in the list front
425 SymbolList.push_front(SectionSym);
431 // Emit the symbol table now, if non-empty.
434 // Emit the relocation sections.
437 // Emit the sections string table.
438 EmitSectionTableStringTable();
440 // Dump the sections and section table to the .o file.
441 OutputSectionsAndSectionTable();
443 // We are done with the abstract symbols.
447 // Release the name mangler object.
448 delete Mang; Mang = 0;
452 /// EmitRelocations - Emit relocations
453 void ELFWriter::EmitRelocations() {
455 // Create Relocation sections for each section which needs it.
456 for (std::list<ELFSection>::iterator I = SectionList.begin(),
457 E = SectionList.end(); I != E; ++I) {
459 // This section does not have relocations
460 if (!I->hasRelocations()) continue;
462 // Get the relocation section for section 'I'
463 bool HasRelA = TEW->hasRelocationAddend();
464 ELFSection &RelSec = getRelocSection(I->getName(), HasRelA,
465 TEW->getPrefELFAlignment());
467 // 'Link' - Section hdr idx of the associated symbol table
468 // 'Info' - Section hdr idx of the section to which the relocation applies
469 ELFSection &SymTab = getSymbolTableSection();
470 RelSec.Link = SymTab.SectionIdx;
471 RelSec.Info = I->SectionIdx;
472 RelSec.EntSize = TEW->getRelocationEntrySize();
474 // Get the relocations from Section
475 std::vector<MachineRelocation> Relos = I->getRelocations();
476 for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
477 MRE = Relos.end(); MRI != MRE; ++MRI) {
478 MachineRelocation &MR = *MRI;
480 // Offset from the start of the section containing the symbol
481 unsigned Offset = MR.getMachineCodeOffset();
483 // Symbol index in the symbol table
486 // Target specific ELF relocation type
487 unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
489 // Constant addend used to compute the value to be stored
490 // into the relocatable field
493 // There are several machine relocations types, and each one of
494 // them needs a different approach to retrieve the symbol table index.
495 if (MR.isGlobalValue()) {
496 const GlobalValue *G = MR.getGlobalValue();
497 SymIdx = GblSymLookup[G];
498 Addend = TEW->getAddendForRelTy(RelType);
500 unsigned SectionIdx = MR.getConstantVal();
501 // TODO: use a map for this.
502 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
503 E = SymbolList.end(); I != E; ++I)
504 if ((SectionIdx == I->SectionIdx) &&
505 (I->getType() == ELFSym::STT_SECTION)) {
506 SymIdx = I->SymTabIdx;
509 Addend = (uint64_t)MR.getResultPointer();
512 // Get the relocation entry and emit to the relocation section
513 ELFRelocation Rel(Offset, SymIdx, RelType, HasRelA, Addend);
514 EmitRelocation(RelSec, Rel, HasRelA);
519 /// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
520 void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
522 RelSec.emitWord(Rel.getOffset());
523 RelSec.emitWord(Rel.getInfo(is64Bit));
525 RelSec.emitWord(Rel.getAddend());
528 /// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
529 void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
531 SymbolTable.emitWord32(Sym.NameIdx);
532 SymbolTable.emitByte(Sym.Info);
533 SymbolTable.emitByte(Sym.Other);
534 SymbolTable.emitWord16(Sym.SectionIdx);
535 SymbolTable.emitWord64(Sym.Value);
536 SymbolTable.emitWord64(Sym.Size);
538 SymbolTable.emitWord32(Sym.NameIdx);
539 SymbolTable.emitWord32(Sym.Value);
540 SymbolTable.emitWord32(Sym.Size);
541 SymbolTable.emitByte(Sym.Info);
542 SymbolTable.emitByte(Sym.Other);
543 SymbolTable.emitWord16(Sym.SectionIdx);
547 /// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
548 /// Section Header Table
549 void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
550 const ELFSection &SHdr) {
551 SHdrTab.emitWord32(SHdr.NameIdx);
552 SHdrTab.emitWord32(SHdr.Type);
554 SHdrTab.emitWord64(SHdr.Flags);
555 SHdrTab.emitWord(SHdr.Addr);
556 SHdrTab.emitWord(SHdr.Offset);
557 SHdrTab.emitWord64(SHdr.Size);
558 SHdrTab.emitWord32(SHdr.Link);
559 SHdrTab.emitWord32(SHdr.Info);
560 SHdrTab.emitWord64(SHdr.Align);
561 SHdrTab.emitWord64(SHdr.EntSize);
563 SHdrTab.emitWord32(SHdr.Flags);
564 SHdrTab.emitWord(SHdr.Addr);
565 SHdrTab.emitWord(SHdr.Offset);
566 SHdrTab.emitWord32(SHdr.Size);
567 SHdrTab.emitWord32(SHdr.Link);
568 SHdrTab.emitWord32(SHdr.Info);
569 SHdrTab.emitWord32(SHdr.Align);
570 SHdrTab.emitWord32(SHdr.EntSize);
574 /// EmitStringTable - If the current symbol table is non-empty, emit the string
576 void ELFWriter::EmitStringTable() {
577 if (!SymbolList.size()) return; // Empty symbol table.
578 ELFSection &StrTab = getStringTableSection();
580 // Set the zero'th symbol to a null byte, as required.
583 // Walk on the symbol list and write symbol names into the
586 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
587 E = SymbolList.end(); I != E; ++I) {
589 // Use the name mangler to uniquify the LLVM symbol.
591 if (I->GV) Name.append(Mang->getValueName(I->GV));
597 StrTab.emitString(Name);
599 // Keep track of the number of bytes emitted to this section.
600 Index += Name.size()+1;
603 assert(Index == StrTab.size());
607 /// EmitSymbolTable - Emit the symbol table itself.
608 void ELFWriter::EmitSymbolTable() {
609 if (!SymbolList.size()) return; // Empty symbol table.
611 unsigned FirstNonLocalSymbol = 1;
612 // Now that we have emitted the string table and know the offset into the
613 // string table of each symbol, emit the symbol table itself.
614 ELFSection &SymTab = getSymbolTableSection();
615 SymTab.Align = TEW->getPrefELFAlignment();
617 // Section Index of .strtab.
618 SymTab.Link = getStringTableSection().SectionIdx;
620 // Size of each symtab entry.
621 SymTab.EntSize = TEW->getSymTabEntrySize();
623 // The first entry in the symtab is the null symbol
624 ELFSym NullSym = ELFSym(0);
625 EmitSymbol(SymTab, NullSym);
627 // Emit all the symbols to the symbol table. Skip the null
628 // symbol, cause it's emitted already
630 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
631 E = SymbolList.end(); I != E; ++I, ++Index) {
632 // Keep track of the first non-local symbol
633 if (I->getBind() == ELFSym::STB_LOCAL)
634 FirstNonLocalSymbol++;
636 // Emit symbol to the symbol table
637 EmitSymbol(SymTab, *I);
639 // Record the symbol table index for each global value
641 GblSymLookup[I->GV] = Index;
643 // Keep track on the symbol index into the symbol table
644 I->SymTabIdx = Index;
647 SymTab.Info = FirstNonLocalSymbol;
648 SymTab.Size = SymTab.size();
651 /// EmitSectionTableStringTable - This method adds and emits a section for the
652 /// ELF Section Table string table: the string table that holds all of the
654 void ELFWriter::EmitSectionTableStringTable() {
655 // First step: add the section for the string table to the list of sections:
656 ELFSection &SHStrTab = getSectionHeaderStringTableSection();
658 // Now that we know which section number is the .shstrtab section, update the
659 // e_shstrndx entry in the ELF header.
660 ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
662 // Set the NameIdx of each section in the string table and emit the bytes for
666 for (std::list<ELFSection>::iterator I = SectionList.begin(),
667 E = SectionList.end(); I != E; ++I) {
668 // Set the index into the table. Note if we have lots of entries with
669 // common suffixes, we could memoize them here if we cared.
671 SHStrTab.emitString(I->getName());
673 // Keep track of the number of bytes emitted to this section.
674 Index += I->getName().size()+1;
677 // Set the size of .shstrtab now that we know what it is.
678 assert(Index == SHStrTab.size());
679 SHStrTab.Size = Index;
682 /// OutputSectionsAndSectionTable - Now that we have constructed the file header
683 /// and all of the sections, emit these to the ostream destination and emit the
685 void ELFWriter::OutputSectionsAndSectionTable() {
686 // Pass #1: Compute the file offset for each section.
687 size_t FileOff = ElfHdr.size(); // File header first.
689 // Adjust alignment of all section if needed.
690 for (std::list<ELFSection>::iterator I = SectionList.begin(),
691 E = SectionList.end(); I != E; ++I) {
693 // Section idx 0 has 0 offset
702 // Update Section size
706 // Align FileOff to whatever the alignment restrictions of the section are.
708 FileOff = (FileOff+I->Align-1) & ~(I->Align-1);
714 // Align Section Header.
715 unsigned TableAlign = TEW->getPrefELFAlignment();
716 FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
718 // Now that we know where all of the sections will be emitted, set the e_shnum
719 // entry in the ELF header.
720 ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
722 // Now that we know the offset in the file of the section table, update the
723 // e_shoff address in the ELF header.
724 ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
726 // Now that we know all of the data in the file header, emit it and all of the
728 O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
729 FileOff = ElfHdr.size();
731 // Section Header Table blob
732 BinaryObject SHdrTable(isLittleEndian, is64Bit);
734 // Emit all of sections to the file and build the section header table.
735 while (!SectionList.empty()) {
736 ELFSection &S = *SectionList.begin();
737 DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
738 << ", Size: " << S.Size << ", Offset: " << S.Offset
739 << ", SectionData Size: " << S.size() << "\n";
741 // Align FileOff to whatever the alignment restrictions of the section are.
744 for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
745 FileOff != NewFileOff; ++FileOff)
748 O.write((char *)&S.getData()[0], S.Size);
752 EmitSectionHeader(SHdrTable, S);
753 SectionList.pop_front();
756 // Align output for the section table.
757 for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
758 FileOff != NewFileOff; ++FileOff)
761 // Emit the section table itself.
762 O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());