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/ObjectCodeEmitter.h"
44 #include "llvm/CodeGen/MachineCodeEmitter.h"
45 #include "llvm/CodeGen/MachineConstantPool.h"
46 #include "llvm/Target/TargetAsmInfo.h"
47 #include "llvm/Target/TargetData.h"
48 #include "llvm/Target/TargetELFWriterInfo.h"
49 #include "llvm/Target/TargetMachine.h"
50 #include "llvm/Support/Mangler.h"
51 #include "llvm/Support/Streams.h"
52 #include "llvm/Support/raw_ostream.h"
53 #include "llvm/Support/Debug.h"
57 char ELFWriter::ID = 0;
59 /// AddELFWriter - Add the ELF writer to the function pass manager
60 ObjectCodeEmitter *llvm::AddELFWriter(PassManagerBase &PM,
63 ELFWriter *EW = new ELFWriter(O, TM);
65 return EW->getObjectCodeEmitter();
68 //===----------------------------------------------------------------------===//
69 // ELFWriter Implementation
70 //===----------------------------------------------------------------------===//
72 ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
73 : MachineFunctionPass(&ID), O(o), TM(tm),
74 is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
75 isLittleEndian(TM.getTargetData()->isLittleEndian()),
76 ElfHdr(isLittleEndian, is64Bit) {
78 TAI = TM.getTargetAsmInfo();
79 TEW = TM.getELFWriterInfo();
81 // Create the object code emitter object for this target.
82 ElfCE = new ELFCodeEmitter(*this);
84 // Inital number of sections
88 ELFWriter::~ELFWriter() {
92 // doInitialization - Emit the file header and all of the global variables for
93 // the module to the ELF file.
94 bool ELFWriter::doInitialization(Module &M) {
95 Mang = new Mangler(M);
99 // Fields e_shnum e_shstrndx are only known after all section have
100 // been emitted. They locations in the ouput buffer are recorded so
101 // to be patched up later.
105 // emitWord method behaves differently for ELF32 and ELF64, writing
106 // 4 bytes in the former and 8 in the last for *_off and *_addr elf types
108 ElfHdr.emitByte(0x7f); // e_ident[EI_MAG0]
109 ElfHdr.emitByte('E'); // e_ident[EI_MAG1]
110 ElfHdr.emitByte('L'); // e_ident[EI_MAG2]
111 ElfHdr.emitByte('F'); // e_ident[EI_MAG3]
113 ElfHdr.emitByte(TEW->getEIClass()); // e_ident[EI_CLASS]
114 ElfHdr.emitByte(TEW->getEIData()); // e_ident[EI_DATA]
115 ElfHdr.emitByte(EV_CURRENT); // e_ident[EI_VERSION]
116 ElfHdr.emitAlignment(16); // e_ident[EI_NIDENT-EI_PAD]
118 ElfHdr.emitWord16(ET_REL); // e_type
119 ElfHdr.emitWord16(TEW->getEMachine()); // e_machine = target
120 ElfHdr.emitWord32(EV_CURRENT); // e_version
121 ElfHdr.emitWord(0); // e_entry, no entry point in .o file
122 ElfHdr.emitWord(0); // e_phoff, no program header for .o
123 ELFHdr_e_shoff_Offset = ElfHdr.size();
124 ElfHdr.emitWord(0); // e_shoff = sec hdr table off in bytes
125 ElfHdr.emitWord32(TEW->getEFlags()); // e_flags = whatever the target wants
126 ElfHdr.emitWord16(TEW->getHdrSize()); // e_ehsize = ELF header size
127 ElfHdr.emitWord16(0); // e_phentsize = prog header entry size
128 ElfHdr.emitWord16(0); // e_phnum = # prog header entries = 0
130 // e_shentsize = Section header entry size
131 ElfHdr.emitWord16(TEW->getSHdrSize());
133 // e_shnum = # of section header ents
134 ELFHdr_e_shnum_Offset = ElfHdr.size();
135 ElfHdr.emitWord16(0); // Placeholder
137 // e_shstrndx = Section # of '.shstrtab'
138 ELFHdr_e_shstrndx_Offset = ElfHdr.size();
139 ElfHdr.emitWord16(0); // Placeholder
141 // Add the null section, which is required to be first in the file.
147 unsigned ELFWriter::getGlobalELFVisibility(const GlobalValue *GV) {
148 switch (GV->getVisibility()) {
150 assert(0 && "unknown visibility type");
151 case GlobalValue::DefaultVisibility:
152 return ELFSym::STV_DEFAULT;
153 case GlobalValue::HiddenVisibility:
154 return ELFSym::STV_HIDDEN;
155 case GlobalValue::ProtectedVisibility:
156 return ELFSym::STV_PROTECTED;
162 unsigned ELFWriter::getGlobalELFLinkage(const GlobalValue *GV) {
163 if (GV->hasInternalLinkage())
164 return ELFSym::STB_LOCAL;
166 if (GV->hasWeakLinkage())
167 return ELFSym::STB_WEAK;
169 return ELFSym::STB_GLOBAL;
172 // getElfSectionFlags - Get the ELF Section Header based on the
173 // flags defined in ELFTargetAsmInfo.
174 unsigned ELFWriter::getElfSectionFlags(unsigned Flags) {
175 unsigned ElfSectionFlags = ELFSection::SHF_ALLOC;
177 if (Flags & SectionFlags::Code)
178 ElfSectionFlags |= ELFSection::SHF_EXECINSTR;
179 if (Flags & SectionFlags::Writeable)
180 ElfSectionFlags |= ELFSection::SHF_WRITE;
181 if (Flags & SectionFlags::Mergeable)
182 ElfSectionFlags |= ELFSection::SHF_MERGE;
183 if (Flags & SectionFlags::TLS)
184 ElfSectionFlags |= ELFSection::SHF_TLS;
185 if (Flags & SectionFlags::Strings)
186 ElfSectionFlags |= ELFSection::SHF_STRINGS;
188 return ElfSectionFlags;
191 // For global symbols without a section, return the Null section as a
193 ELFSection &ELFWriter::getGlobalSymELFSection(const GlobalVariable *GV,
195 // If this is a declaration, the symbol does not have a section.
196 if (!GV->hasInitializer()) {
197 Sym.SectionIdx = ELFSection::SHN_UNDEF;
198 return getNullSection();
201 // Get the name and flags of the section for the global
202 const Section *S = TAI->SectionForGlobal(GV);
203 unsigned SectionType = ELFSection::SHT_PROGBITS;
204 unsigned SectionFlags = getElfSectionFlags(S->getFlags());
205 DOUT << "Section " << S->getName() << " for global " << GV->getName() << "\n";
207 const TargetData *TD = TM.getTargetData();
208 unsigned Align = TD->getPreferredAlignment(GV);
209 Constant *CV = GV->getInitializer();
211 // If this global has a zero initializer, go to .bss or common section.
212 // Variables are part of the common block if they are zero initialized
213 // and allowed to be merged with other symbols.
214 if (CV->isNullValue() || isa<UndefValue>(CV)) {
215 SectionType = ELFSection::SHT_NOBITS;
216 ELFSection &ElfS = getSection(S->getName(), SectionType, SectionFlags);
217 if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
218 GV->hasCommonLinkage()) {
219 Sym.SectionIdx = ELFSection::SHN_COMMON;
225 Sym.SectionIdx = ElfS.SectionIdx;
226 if (Align) ElfS.Size = (ElfS.Size + Align-1) & ~(Align-1);
227 ElfS.Align = std::max(ElfS.Align, Align);
231 Sym.IsConstant = true;
232 ELFSection &ElfS = getSection(S->getName(), SectionType, SectionFlags);
233 Sym.SectionIdx = ElfS.SectionIdx;
234 ElfS.Align = std::max(ElfS.Align, Align);
238 void ELFWriter::EmitFunctionDeclaration(const Function *F) {
240 GblSym.setBind(ELFSym::STB_GLOBAL);
241 GblSym.setType(ELFSym::STT_NOTYPE);
242 GblSym.setVisibility(ELFSym::STV_DEFAULT);
243 GblSym.SectionIdx = ELFSection::SHN_UNDEF;
244 SymbolList.push_back(GblSym);
247 void ELFWriter::EmitGlobalVar(const GlobalVariable *GV) {
248 unsigned SymBind = getGlobalELFLinkage(GV);
249 unsigned Align=0, Size=0;
251 GblSym.setBind(SymBind);
252 GblSym.setVisibility(getGlobalELFVisibility(GV));
254 if (GV->hasInitializer()) {
255 GblSym.setType(ELFSym::STT_OBJECT);
256 const TargetData *TD = TM.getTargetData();
257 Align = TD->getPreferredAlignment(GV);
258 Size = TD->getTypeAllocSize(GV->getInitializer()->getType());
261 GblSym.setType(ELFSym::STT_NOTYPE);
264 ELFSection &GblSection = getGlobalSymELFSection(GV, GblSym);
266 if (GblSym.IsCommon) {
267 GblSym.Value = Align;
268 } else if (GblSym.IsBss) {
269 GblSym.Value = GblSection.Size;
270 GblSection.Size += Size;
271 } else if (GblSym.IsConstant){
272 // GblSym.Value should contain the symbol index inside the section,
273 // and all symbols should start on their required alignment boundary
274 GblSym.Value = (GblSection.size() + (Align-1)) & (-Align);
275 GblSection.emitAlignment(Align);
276 EmitGlobalConstant(GV->getInitializer(), GblSection);
279 // Local symbols should come first on the symbol table.
280 if (!GV->hasPrivateLinkage()) {
281 if (SymBind == ELFSym::STB_LOCAL)
282 SymbolList.push_front(GblSym);
284 SymbolList.push_back(GblSym);
288 void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
291 // Print the fields in successive locations. Pad to align if needed!
292 const TargetData *TD = TM.getTargetData();
293 unsigned Size = TD->getTypeAllocSize(CVS->getType());
294 const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
295 uint64_t sizeSoFar = 0;
296 for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
297 const Constant* field = CVS->getOperand(i);
299 // Check if padding is needed and insert one or more 0s.
300 uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
301 uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
302 - cvsLayout->getElementOffset(i)) - fieldSize;
303 sizeSoFar += fieldSize + padSize;
305 // Now print the actual field value.
306 EmitGlobalConstant(field, GblS);
308 // Insert padding - this may include padding to increase the size of the
309 // current field up to the ABI size (if the struct is not packed) as well
310 // as padding to ensure that the next field starts at the right offset.
311 for (unsigned p=0; p < padSize; p++)
314 assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
315 "Layout of constant struct may be incorrect!");
318 void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
319 const TargetData *TD = TM.getTargetData();
320 unsigned Size = TD->getTypeAllocSize(CV->getType());
322 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
323 if (CVA->isString()) {
324 std::string GblStr = CVA->getAsString();
325 GblStr.resize(GblStr.size()-1);
326 GblS.emitString(GblStr);
327 } else { // Not a string. Print the values in successive locations
328 for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
329 EmitGlobalConstant(CVA->getOperand(i), GblS);
332 } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
333 EmitGlobalConstantStruct(CVS, GblS);
335 } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
336 uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
337 if (CFP->getType() == Type::DoubleTy)
338 GblS.emitWord64(Val);
339 else if (CFP->getType() == Type::FloatTy)
340 GblS.emitWord32(Val);
341 else if (CFP->getType() == Type::X86_FP80Ty) {
342 assert(0 && "X86_FP80Ty global emission not implemented");
343 } else if (CFP->getType() == Type::PPC_FP128Ty)
344 assert(0 && "PPC_FP128Ty global emission not implemented");
346 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
348 GblS.emitWord32(CI->getZExtValue());
350 GblS.emitWord64(CI->getZExtValue());
352 assert(0 && "LargeInt global emission not implemented");
354 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
355 const VectorType *PTy = CP->getType();
356 for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
357 EmitGlobalConstant(CP->getOperand(I), GblS);
360 assert(0 && "unknown global constant");
364 bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
365 // Nothing to do here, this is all done through the ElfCE object above.
369 /// doFinalization - Now that the module has been completely processed, emit
370 /// the ELF file to 'O'.
371 bool ELFWriter::doFinalization(Module &M) {
372 // Emit .data section placeholder
375 // Emit .bss section placeholder
378 // Build and emit data, bss and "common" sections.
379 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
385 // Emit all pending globals
386 // TODO: this should be done only for referenced symbols
387 for (SetVector<GlobalValue*>::const_iterator I = PendingGlobals.begin(),
388 E = PendingGlobals.end(); I != E; ++I) {
390 // No need to emit the symbol again
391 if (GblSymLookup.find(*I) != GblSymLookup.end())
394 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(*I)) {
396 } else if (Function *F = dyn_cast<Function>(*I)) {
397 // If function is not in GblSymLookup, it doesn't have a body,
398 // so emit the symbol as a function declaration (no section associated)
399 EmitFunctionDeclaration(F);
401 assert("unknown howto handle pending global");
403 GblSymLookup[*I] = 0;
406 // Emit non-executable stack note
407 if (TAI->getNonexecutableStackDirective())
408 getNonExecStackSection();
410 // Emit a symbol for each section created until now
411 for (std::map<std::string, ELFSection*>::iterator I = SectionLookup.begin(),
412 E = SectionLookup.end(); I != E; ++I) {
413 ELFSection *ES = I->second;
416 if (ES->SectionIdx == 0) continue;
418 ELFSym SectionSym(0);
419 SectionSym.SectionIdx = ES->SectionIdx;
421 SectionSym.setBind(ELFSym::STB_LOCAL);
422 SectionSym.setType(ELFSym::STT_SECTION);
423 SectionSym.setVisibility(ELFSym::STV_DEFAULT);
425 // Local symbols go in the list front
426 SymbolList.push_front(SectionSym);
432 // Emit the symbol table now, if non-empty.
435 // Emit the relocation sections.
438 // Emit the sections string table.
439 EmitSectionTableStringTable();
441 // Dump the sections and section table to the .o file.
442 OutputSectionsAndSectionTable();
444 // We are done with the abstract symbols.
448 // Release the name mangler object.
449 delete Mang; Mang = 0;
453 /// EmitRelocations - Emit relocations
454 void ELFWriter::EmitRelocations() {
456 // Create Relocation sections for each section which needs it.
457 for (std::list<ELFSection>::iterator I = SectionList.begin(),
458 E = SectionList.end(); I != E; ++I) {
460 // This section does not have relocations
461 if (!I->hasRelocations()) continue;
463 // Get the relocation section for section 'I'
464 bool HasRelA = TEW->hasRelocationAddend();
465 ELFSection &RelSec = getRelocSection(I->getName(), HasRelA,
466 TEW->getPrefELFAlignment());
468 // 'Link' - Section hdr idx of the associated symbol table
469 // 'Info' - Section hdr idx of the section to which the relocation applies
470 ELFSection &SymTab = getSymbolTableSection();
471 RelSec.Link = SymTab.SectionIdx;
472 RelSec.Info = I->SectionIdx;
473 RelSec.EntSize = TEW->getRelocationEntrySize();
475 // Get the relocations from Section
476 std::vector<MachineRelocation> Relos = I->getRelocations();
477 for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
478 MRE = Relos.end(); MRI != MRE; ++MRI) {
479 MachineRelocation &MR = *MRI;
481 // Offset from the start of the section containing the symbol
482 unsigned Offset = MR.getMachineCodeOffset();
484 // Symbol index in the symbol table
487 // Target specific ELF relocation type
488 unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
490 // Constant addend used to compute the value to be stored
491 // into the relocatable field
494 // There are several machine relocations types, and each one of
495 // them needs a different approach to retrieve the symbol table index.
496 if (MR.isGlobalValue()) {
497 const GlobalValue *G = MR.getGlobalValue();
498 SymIdx = GblSymLookup[G];
499 Addend = TEW->getAddendForRelTy(RelType);
501 unsigned SectionIdx = MR.getConstantVal();
502 // TODO: use a map for this.
503 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
504 E = SymbolList.end(); I != E; ++I)
505 if ((SectionIdx == I->SectionIdx) &&
506 (I->getType() == ELFSym::STT_SECTION)) {
507 SymIdx = I->SymTabIdx;
510 Addend = (uint64_t)MR.getResultPointer();
513 // Get the relocation entry and emit to the relocation section
514 ELFRelocation Rel(Offset, SymIdx, RelType, HasRelA, Addend);
515 EmitRelocation(RelSec, Rel, HasRelA);
520 /// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
521 void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
523 RelSec.emitWord(Rel.getOffset());
524 RelSec.emitWord(Rel.getInfo(is64Bit));
526 RelSec.emitWord(Rel.getAddend());
529 /// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
530 void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
532 SymbolTable.emitWord32(Sym.NameIdx);
533 SymbolTable.emitByte(Sym.Info);
534 SymbolTable.emitByte(Sym.Other);
535 SymbolTable.emitWord16(Sym.SectionIdx);
536 SymbolTable.emitWord64(Sym.Value);
537 SymbolTable.emitWord64(Sym.Size);
539 SymbolTable.emitWord32(Sym.NameIdx);
540 SymbolTable.emitWord32(Sym.Value);
541 SymbolTable.emitWord32(Sym.Size);
542 SymbolTable.emitByte(Sym.Info);
543 SymbolTable.emitByte(Sym.Other);
544 SymbolTable.emitWord16(Sym.SectionIdx);
548 /// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
549 /// Section Header Table
550 void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
551 const ELFSection &SHdr) {
552 SHdrTab.emitWord32(SHdr.NameIdx);
553 SHdrTab.emitWord32(SHdr.Type);
555 SHdrTab.emitWord64(SHdr.Flags);
556 SHdrTab.emitWord(SHdr.Addr);
557 SHdrTab.emitWord(SHdr.Offset);
558 SHdrTab.emitWord64(SHdr.Size);
559 SHdrTab.emitWord32(SHdr.Link);
560 SHdrTab.emitWord32(SHdr.Info);
561 SHdrTab.emitWord64(SHdr.Align);
562 SHdrTab.emitWord64(SHdr.EntSize);
564 SHdrTab.emitWord32(SHdr.Flags);
565 SHdrTab.emitWord(SHdr.Addr);
566 SHdrTab.emitWord(SHdr.Offset);
567 SHdrTab.emitWord32(SHdr.Size);
568 SHdrTab.emitWord32(SHdr.Link);
569 SHdrTab.emitWord32(SHdr.Info);
570 SHdrTab.emitWord32(SHdr.Align);
571 SHdrTab.emitWord32(SHdr.EntSize);
575 /// EmitStringTable - If the current symbol table is non-empty, emit the string
577 void ELFWriter::EmitStringTable() {
578 if (!SymbolList.size()) return; // Empty symbol table.
579 ELFSection &StrTab = getStringTableSection();
581 // Set the zero'th symbol to a null byte, as required.
584 // Walk on the symbol list and write symbol names into the
587 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
588 E = SymbolList.end(); I != E; ++I) {
590 // Use the name mangler to uniquify the LLVM symbol.
592 if (I->GV) Name.append(Mang->getValueName(I->GV));
598 StrTab.emitString(Name);
600 // Keep track of the number of bytes emitted to this section.
601 Index += Name.size()+1;
604 assert(Index == StrTab.size());
608 /// EmitSymbolTable - Emit the symbol table itself.
609 void ELFWriter::EmitSymbolTable() {
610 if (!SymbolList.size()) return; // Empty symbol table.
612 unsigned FirstNonLocalSymbol = 1;
613 // Now that we have emitted the string table and know the offset into the
614 // string table of each symbol, emit the symbol table itself.
615 ELFSection &SymTab = getSymbolTableSection();
616 SymTab.Align = TEW->getPrefELFAlignment();
618 // Section Index of .strtab.
619 SymTab.Link = getStringTableSection().SectionIdx;
621 // Size of each symtab entry.
622 SymTab.EntSize = TEW->getSymTabEntrySize();
624 // The first entry in the symtab is the null symbol
625 ELFSym NullSym = ELFSym(0);
626 EmitSymbol(SymTab, NullSym);
628 // Emit all the symbols to the symbol table. Skip the null
629 // symbol, cause it's emitted already
631 for (std::list<ELFSym>::iterator I = SymbolList.begin(),
632 E = SymbolList.end(); I != E; ++I, ++Index) {
633 // Keep track of the first non-local symbol
634 if (I->getBind() == ELFSym::STB_LOCAL)
635 FirstNonLocalSymbol++;
637 // Emit symbol to the symbol table
638 EmitSymbol(SymTab, *I);
640 // Record the symbol table index for each global value
642 GblSymLookup[I->GV] = Index;
644 // Keep track on the symbol index into the symbol table
645 I->SymTabIdx = Index;
648 SymTab.Info = FirstNonLocalSymbol;
649 SymTab.Size = SymTab.size();
652 /// EmitSectionTableStringTable - This method adds and emits a section for the
653 /// ELF Section Table string table: the string table that holds all of the
655 void ELFWriter::EmitSectionTableStringTable() {
656 // First step: add the section for the string table to the list of sections:
657 ELFSection &SHStrTab = getSectionHeaderStringTableSection();
659 // Now that we know which section number is the .shstrtab section, update the
660 // e_shstrndx entry in the ELF header.
661 ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
663 // Set the NameIdx of each section in the string table and emit the bytes for
667 for (std::list<ELFSection>::iterator I = SectionList.begin(),
668 E = SectionList.end(); I != E; ++I) {
669 // Set the index into the table. Note if we have lots of entries with
670 // common suffixes, we could memoize them here if we cared.
672 SHStrTab.emitString(I->getName());
674 // Keep track of the number of bytes emitted to this section.
675 Index += I->getName().size()+1;
678 // Set the size of .shstrtab now that we know what it is.
679 assert(Index == SHStrTab.size());
680 SHStrTab.Size = Index;
683 /// OutputSectionsAndSectionTable - Now that we have constructed the file header
684 /// and all of the sections, emit these to the ostream destination and emit the
686 void ELFWriter::OutputSectionsAndSectionTable() {
687 // Pass #1: Compute the file offset for each section.
688 size_t FileOff = ElfHdr.size(); // File header first.
690 // Adjust alignment of all section if needed.
691 for (std::list<ELFSection>::iterator I = SectionList.begin(),
692 E = SectionList.end(); I != E; ++I) {
694 // Section idx 0 has 0 offset
703 // Update Section size
707 // Align FileOff to whatever the alignment restrictions of the section are.
709 FileOff = (FileOff+I->Align-1) & ~(I->Align-1);
715 // Align Section Header.
716 unsigned TableAlign = TEW->getPrefELFAlignment();
717 FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
719 // Now that we know where all of the sections will be emitted, set the e_shnum
720 // entry in the ELF header.
721 ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
723 // Now that we know the offset in the file of the section table, update the
724 // e_shoff address in the ELF header.
725 ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
727 // Now that we know all of the data in the file header, emit it and all of the
729 O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
730 FileOff = ElfHdr.size();
732 // Section Header Table blob
733 BinaryObject SHdrTable(isLittleEndian, is64Bit);
735 // Emit all of sections to the file and build the section header table.
736 while (!SectionList.empty()) {
737 ELFSection &S = *SectionList.begin();
738 DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
739 << ", Size: " << S.Size << ", Offset: " << S.Offset
740 << ", SectionData Size: " << S.size() << "\n";
742 // Align FileOff to whatever the alignment restrictions of the section are.
745 for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
746 FileOff != NewFileOff; ++FileOff)
749 O.write((char *)&S.getData()[0], S.Size);
753 EmitSectionHeader(SHdrTable, S);
754 SectionList.pop_front();
757 // Align output for the section table.
758 for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
759 FileOff != NewFileOff; ++FileOff)
762 // Emit the section table itself.
763 O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());