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"
54 #include "llvm/Support/ErrorHandling.h"
58 char ELFWriter::ID = 0;
60 /// AddELFWriter - Add the ELF writer to the function pass manager
61 ObjectCodeEmitter *llvm::AddELFWriter(PassManagerBase &PM,
64 ELFWriter *EW = new ELFWriter(O, TM);
66 return EW->getObjectCodeEmitter();
69 //===----------------------------------------------------------------------===//
70 // ELFWriter Implementation
71 //===----------------------------------------------------------------------===//
73 ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
74 : MachineFunctionPass(&ID), O(o), TM(tm),
75 is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
76 isLittleEndian(TM.getTargetData()->isLittleEndian()),
77 ElfHdr(isLittleEndian, is64Bit) {
79 TAI = TM.getTargetAsmInfo();
80 TEW = TM.getELFWriterInfo();
82 // Create the object code emitter object for this target.
83 ElfCE = new ELFCodeEmitter(*this);
85 // Inital number of sections
89 ELFWriter::~ELFWriter() {
93 // doInitialization - Emit the file header and all of the global variables for
94 // the module to the ELF file.
95 bool ELFWriter::doInitialization(Module &M) {
96 Mang = new Mangler(M);
100 // Fields e_shnum e_shstrndx are only known after all section have
101 // been emitted. They locations in the ouput buffer are recorded so
102 // to be patched up later.
106 // emitWord method behaves differently for ELF32 and ELF64, writing
107 // 4 bytes in the former and 8 in the last for *_off and *_addr elf types
109 ElfHdr.emitByte(0x7f); // e_ident[EI_MAG0]
110 ElfHdr.emitByte('E'); // e_ident[EI_MAG1]
111 ElfHdr.emitByte('L'); // e_ident[EI_MAG2]
112 ElfHdr.emitByte('F'); // e_ident[EI_MAG3]
114 ElfHdr.emitByte(TEW->getEIClass()); // e_ident[EI_CLASS]
115 ElfHdr.emitByte(TEW->getEIData()); // e_ident[EI_DATA]
116 ElfHdr.emitByte(EV_CURRENT); // e_ident[EI_VERSION]
117 ElfHdr.emitAlignment(16); // e_ident[EI_NIDENT-EI_PAD]
119 ElfHdr.emitWord16(ET_REL); // e_type
120 ElfHdr.emitWord16(TEW->getEMachine()); // e_machine = target
121 ElfHdr.emitWord32(EV_CURRENT); // e_version
122 ElfHdr.emitWord(0); // e_entry, no entry point in .o file
123 ElfHdr.emitWord(0); // e_phoff, no program header for .o
124 ELFHdr_e_shoff_Offset = ElfHdr.size();
125 ElfHdr.emitWord(0); // e_shoff = sec hdr table off in bytes
126 ElfHdr.emitWord32(TEW->getEFlags()); // e_flags = whatever the target wants
127 ElfHdr.emitWord16(TEW->getHdrSize()); // e_ehsize = ELF header size
128 ElfHdr.emitWord16(0); // e_phentsize = prog header entry size
129 ElfHdr.emitWord16(0); // e_phnum = # prog header entries = 0
131 // e_shentsize = Section header entry size
132 ElfHdr.emitWord16(TEW->getSHdrSize());
134 // e_shnum = # of section header ents
135 ELFHdr_e_shnum_Offset = ElfHdr.size();
136 ElfHdr.emitWord16(0); // Placeholder
138 // e_shstrndx = Section # of '.shstrtab'
139 ELFHdr_e_shstrndx_Offset = ElfHdr.size();
140 ElfHdr.emitWord16(0); // Placeholder
142 // Add the null section, which is required to be first in the file.
148 // Get jump table section on the section name returned by TAI
149 ELFSection &ELFWriter::getJumpTableSection() {
150 unsigned Align = TM.getTargetData()->getPointerABIAlignment();
151 return getSection(TAI->getJumpTableDataSection(),
152 ELFSection::SHT_PROGBITS,
153 ELFSection::SHF_ALLOC, Align);
156 // Get a constant pool section based on the section name returned by TAI
157 ELFSection &ELFWriter::getConstantPoolSection(MachineConstantPoolEntry &CPE) {
158 uint64_t Size = TM.getTargetData()->getTypeAllocSize(CPE.getType());
160 std::string CstPoolName =
161 TAI->getSectionForMergableConstant(Size,CPE.getRelocationInfo())->getName();
162 return getSection(CstPoolName,
163 ELFSection::SHT_PROGBITS,
164 ELFSection::SHF_MERGE | ELFSection::SHF_ALLOC,
168 // Return the relocation section of section 'S'. 'RelA' is true
169 // if the relocation section contains entries with addends.
170 ELFSection &ELFWriter::getRelocSection(ELFSection &S) {
171 unsigned SectionHeaderTy = TEW->hasRelocationAddend() ?
172 ELFSection::SHT_RELA : ELFSection::SHT_REL;
173 std::string RelSName(".rel");
174 if (TEW->hasRelocationAddend())
175 RelSName.append("a");
176 RelSName.append(S.getName());
178 return getSection(RelSName, SectionHeaderTy, 0, TEW->getPrefELFAlignment());
181 // getGlobalELFVisibility - Returns the ELF specific visibility type
182 unsigned ELFWriter::getGlobalELFVisibility(const GlobalValue *GV) {
183 switch (GV->getVisibility()) {
185 llvm_unreachable("unknown visibility type");
186 case GlobalValue::DefaultVisibility:
187 return ELFSym::STV_DEFAULT;
188 case GlobalValue::HiddenVisibility:
189 return ELFSym::STV_HIDDEN;
190 case GlobalValue::ProtectedVisibility:
191 return ELFSym::STV_PROTECTED;
196 // getGlobalELFBinding - Returns the ELF specific binding type
197 unsigned ELFWriter::getGlobalELFBinding(const GlobalValue *GV) {
198 if (GV->hasInternalLinkage())
199 return ELFSym::STB_LOCAL;
201 if (GV->hasWeakLinkage())
202 return ELFSym::STB_WEAK;
204 return ELFSym::STB_GLOBAL;
207 // getGlobalELFType - Returns the ELF specific type for a global
208 unsigned ELFWriter::getGlobalELFType(const GlobalValue *GV) {
209 if (GV->isDeclaration())
210 return ELFSym::STT_NOTYPE;
212 if (isa<Function>(GV))
213 return ELFSym::STT_FUNC;
215 return ELFSym::STT_OBJECT;
218 // getElfSectionFlags - Get the ELF Section Header flags based
219 // on the flags defined in ELFTargetAsmInfo.
220 unsigned ELFWriter::getElfSectionFlags(unsigned Flags) {
221 unsigned ElfSectionFlags = ELFSection::SHF_ALLOC;
223 if (Flags & SectionFlags::Code)
224 ElfSectionFlags |= ELFSection::SHF_EXECINSTR;
225 if (Flags & SectionFlags::Writable)
226 ElfSectionFlags |= ELFSection::SHF_WRITE;
227 if (Flags & SectionFlags::Mergeable)
228 ElfSectionFlags |= ELFSection::SHF_MERGE;
229 if (Flags & SectionFlags::TLS)
230 ElfSectionFlags |= ELFSection::SHF_TLS;
231 if (Flags & SectionFlags::Strings)
232 ElfSectionFlags |= ELFSection::SHF_STRINGS;
234 return ElfSectionFlags;
237 // isELFUndefSym - the symbol has no section and must be placed in
238 // the symbol table with a reference to the null section.
239 static bool isELFUndefSym(const GlobalValue *GV) {
240 return GV->isDeclaration();
243 // isELFBssSym - for an undef or null value, the symbol must go to a bss
244 // section if it's not weak for linker, otherwise it's a common sym.
245 static bool isELFBssSym(const GlobalVariable *GV) {
246 const Constant *CV = GV->getInitializer();
247 return ((CV->isNullValue() || isa<UndefValue>(CV)) && !GV->isWeakForLinker());
250 // isELFCommonSym - for an undef or null value, the symbol must go to a
251 // common section if it's weak for linker, otherwise bss.
252 static bool isELFCommonSym(const GlobalVariable *GV) {
253 const Constant *CV = GV->getInitializer();
254 return ((CV->isNullValue() || isa<UndefValue>(CV)) && GV->isWeakForLinker());
257 // isELFDataSym - if the symbol is an initialized but no null constant
258 // it must go to some kind of data section gathered from TAI
259 static bool isELFDataSym(const Constant *CV) {
260 return (!(CV->isNullValue() || isa<UndefValue>(CV)));
263 // EmitGlobal - Choose the right section for global and emit it
264 void ELFWriter::EmitGlobal(const GlobalValue *GV) {
266 // Check if the referenced symbol is already emitted
267 if (GblSymLookup.find(GV) != GblSymLookup.end())
270 // Handle ELF Bind, Visibility and Type for the current symbol
271 unsigned SymBind = getGlobalELFBinding(GV);
272 ELFSym *GblSym = new ELFSym(GV);
273 GblSym->setBind(SymBind);
274 GblSym->setVisibility(getGlobalELFVisibility(GV));
275 GblSym->setType(getGlobalELFType(GV));
277 if (isELFUndefSym(GV)) {
278 GblSym->SectionIdx = ELFSection::SHN_UNDEF;
280 assert(isa<GlobalVariable>(GV) && "GV not a global variable!");
281 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
283 // Get ELF section from TAI
284 const Section *S = TAI->SectionForGlobal(GV);
285 unsigned SectionFlags = getElfSectionFlags(S->getFlags());
287 // The symbol align should update the section alignment if needed
288 const TargetData *TD = TM.getTargetData();
289 unsigned Align = TD->getPreferredAlignment(GVar);
290 unsigned Size = TD->getTypeAllocSize(GVar->getInitializer()->getType());
293 if (isELFCommonSym(GVar)) {
294 GblSym->SectionIdx = ELFSection::SHN_COMMON;
295 getSection(S->getName(), ELFSection::SHT_NOBITS, SectionFlags, 1);
297 // A new linkonce section is created for each global in the
298 // common section, the default alignment is 1 and the symbol
299 // value contains its alignment.
300 GblSym->Value = Align;
302 } else if (isELFBssSym(GVar)) {
304 getSection(S->getName(), ELFSection::SHT_NOBITS, SectionFlags);
305 GblSym->SectionIdx = ES.SectionIdx;
307 // Update the size with alignment and the next object can
308 // start in the right offset in the section
309 if (Align) ES.Size = (ES.Size + Align-1) & ~(Align-1);
310 ES.Align = std::max(ES.Align, Align);
312 // GblSym->Value should contain the virtual offset inside the section.
313 // Virtual because the BSS space is not allocated on ELF objects
314 GblSym->Value = ES.Size;
317 } else if (isELFDataSym(GV)) {
319 getSection(S->getName(), ELFSection::SHT_PROGBITS, SectionFlags);
320 GblSym->SectionIdx = ES.SectionIdx;
322 // GblSym->Value should contain the symbol offset inside the section,
323 // and all symbols should start on their required alignment boundary
324 ES.Align = std::max(ES.Align, Align);
325 GblSym->Value = (ES.size() + (Align-1)) & (-Align);
326 ES.emitAlignment(ES.Align);
328 // Emit the global to the data section 'ES'
329 EmitGlobalConstant(GVar->getInitializer(), ES);
333 // Private symbols must never go to the symbol table.
335 if (GV->hasPrivateLinkage()) {
336 PrivateSyms.push_back(GblSym);
337 SymIdx = PrivateSyms.size()-1;
339 SymbolList.push_back(GblSym);
342 setGlobalSymLookup(GV, SymIdx);
345 void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
348 // Print the fields in successive locations. Pad to align if needed!
349 const TargetData *TD = TM.getTargetData();
350 unsigned Size = TD->getTypeAllocSize(CVS->getType());
351 const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
352 uint64_t sizeSoFar = 0;
353 for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
354 const Constant* field = CVS->getOperand(i);
356 // Check if padding is needed and insert one or more 0s.
357 uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
358 uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
359 - cvsLayout->getElementOffset(i)) - fieldSize;
360 sizeSoFar += fieldSize + padSize;
362 // Now print the actual field value.
363 EmitGlobalConstant(field, GblS);
365 // Insert padding - this may include padding to increase the size of the
366 // current field up to the ABI size (if the struct is not packed) as well
367 // as padding to ensure that the next field starts at the right offset.
368 for (unsigned p=0; p < padSize; p++)
371 assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
372 "Layout of constant struct may be incorrect!");
375 void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
376 const TargetData *TD = TM.getTargetData();
377 unsigned Size = TD->getTypeAllocSize(CV->getType());
379 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
380 if (CVA->isString()) {
381 std::string GblStr = CVA->getAsString();
382 GblStr.resize(GblStr.size()-1);
383 GblS.emitString(GblStr);
384 } else { // Not a string. Print the values in successive locations
385 for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
386 EmitGlobalConstant(CVA->getOperand(i), GblS);
389 } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
390 EmitGlobalConstantStruct(CVS, GblS);
392 } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
393 uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
394 if (CFP->getType() == Type::DoubleTy)
395 GblS.emitWord64(Val);
396 else if (CFP->getType() == Type::FloatTy)
397 GblS.emitWord32(Val);
398 else if (CFP->getType() == Type::X86_FP80Ty) {
399 llvm_unreachable("X86_FP80Ty global emission not implemented");
400 } else if (CFP->getType() == Type::PPC_FP128Ty)
401 llvm_unreachable("PPC_FP128Ty global emission not implemented");
403 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
405 GblS.emitWord32(CI->getZExtValue());
407 GblS.emitWord64(CI->getZExtValue());
409 llvm_unreachable("LargeInt global emission not implemented");
411 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
412 const VectorType *PTy = CP->getType();
413 for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
414 EmitGlobalConstant(CP->getOperand(I), GblS);
416 } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
417 // This is a constant address for a global variable or function and
418 // therefore must be referenced using a relocation entry.
420 // Check if the referenced symbol is already emitted
421 if (GblSymLookup.find(GV) == GblSymLookup.end())
424 // Create the relocation entry for the global value
425 MachineRelocation MR =
426 MachineRelocation::getGV(GblS.getCurrentPCOffset(),
427 TEW->getAbsoluteLabelMachineRelTy(),
428 const_cast<GlobalValue*>(GV));
430 // Fill the data entry with zeros
431 for (unsigned i=0; i < Size; ++i)
434 // Add the relocation entry for the current data section
435 GblS.addRelocation(MR);
437 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
438 if (CE->getOpcode() == Instruction::BitCast) {
439 EmitGlobalConstant(CE->getOperand(0), GblS);
442 // See AsmPrinter::EmitConstantValueOnly for other ConstantExpr types
443 llvm_unreachable("Unsupported ConstantExpr type");
446 llvm_unreachable("Unknown global constant type");
450 bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
451 // Nothing to do here, this is all done through the ElfCE object above.
455 /// doFinalization - Now that the module has been completely processed, emit
456 /// the ELF file to 'O'.
457 bool ELFWriter::doFinalization(Module &M) {
458 // Emit .data section placeholder
461 // Emit .bss section placeholder
464 // Build and emit data, bss and "common" sections.
465 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
469 // Emit all pending globals
470 for (SetVector<GlobalValue*>::const_iterator I = PendingGlobals.begin(),
471 E = PendingGlobals.end(); I != E; ++I)
474 // Emit non-executable stack note
475 if (TAI->getNonexecutableStackDirective())
476 getNonExecStackSection();
478 // Emit a symbol for each section created until now, skip null section
479 for (unsigned i = 1, e = SectionList.size(); i < e; ++i) {
480 ELFSection &ES = *SectionList[i];
481 ELFSym *SectionSym = new ELFSym(0);
482 SectionSym->SectionIdx = ES.SectionIdx;
483 SectionSym->Size = 0;
484 SectionSym->setBind(ELFSym::STB_LOCAL);
485 SectionSym->setType(ELFSym::STT_SECTION);
486 SectionSym->setVisibility(ELFSym::STV_DEFAULT);
487 SymbolList.push_back(SectionSym);
488 ES.Sym = SymbolList.back();
494 // Emit the symbol table now, if non-empty.
497 // Emit the relocation sections.
500 // Emit the sections string table.
501 EmitSectionTableStringTable();
503 // Dump the sections and section table to the .o file.
504 OutputSectionsAndSectionTable();
506 // We are done with the abstract symbols.
511 // Release the name mangler object.
512 delete Mang; Mang = 0;
516 // RelocateField - Patch relocatable field with 'Offset' in 'BO'
517 // using a 'Value' of known 'Size'
518 void ELFWriter::RelocateField(BinaryObject &BO, uint32_t Offset,
519 int64_t Value, unsigned Size) {
521 BO.fixWord32(Value, Offset);
523 BO.fixWord64(Value, Offset);
525 llvm_unreachable("don't know howto patch relocatable field");
528 /// EmitRelocations - Emit relocations
529 void ELFWriter::EmitRelocations() {
531 // True if the target uses the relocation entry to hold the addend,
532 // otherwise the addend is written directly to the relocatable field.
533 bool HasRelA = TEW->hasRelocationAddend();
535 // Create Relocation sections for each section which needs it.
536 for (unsigned i=0, e=SectionList.size(); i != e; ++i) {
537 ELFSection &S = *SectionList[i];
539 // This section does not have relocations
540 if (!S.hasRelocations()) continue;
541 ELFSection &RelSec = getRelocSection(S);
543 // 'Link' - Section hdr idx of the associated symbol table
544 // 'Info' - Section hdr idx of the section to which the relocation applies
545 ELFSection &SymTab = getSymbolTableSection();
546 RelSec.Link = SymTab.SectionIdx;
547 RelSec.Info = S.SectionIdx;
548 RelSec.EntSize = TEW->getRelocationEntrySize();
550 // Get the relocations from Section
551 std::vector<MachineRelocation> Relos = S.getRelocations();
552 for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
553 MRE = Relos.end(); MRI != MRE; ++MRI) {
554 MachineRelocation &MR = *MRI;
556 // Relocatable field offset from the section start
557 unsigned RelOffset = MR.getMachineCodeOffset();
559 // Symbol index in the symbol table
562 // Target specific relocation field type and size
563 unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
564 unsigned RelTySize = TEW->getRelocationTySize(RelType);
567 // There are several machine relocations types, and each one of
568 // them needs a different approach to retrieve the symbol table index.
569 if (MR.isGlobalValue()) {
570 const GlobalValue *G = MR.getGlobalValue();
571 SymIdx = GblSymLookup[G];
572 if (G->hasPrivateLinkage()) {
573 // If the target uses a section offset in the relocation:
574 // SymIdx + Addend = section sym for global + section offset
575 unsigned SectionIdx = PrivateSyms[SymIdx]->SectionIdx;
576 Addend = PrivateSyms[SymIdx]->Value;
577 SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
579 Addend = TEW->getDefaultAddendForRelTy(RelType);
582 // Get the symbol index for the section symbol
583 unsigned SectionIdx = MR.getConstantVal();
584 SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
585 Addend = (uint64_t)MR.getResultPointer();
587 // For pc relative relocations where symbols are defined in the same
588 // section they are referenced, ignore the relocation entry and patch
589 // the relocatable field with the symbol offset directly.
590 if (S.SectionIdx == SectionIdx && TEW->isPCRelativeRel(RelType)) {
591 int64_t Value = TEW->computeRelocation(Addend, RelOffset, RelType);
592 RelocateField(S, RelOffset, Value, RelTySize);
596 // Handle Jump Table Index relocation
597 if ((SectionIdx == getJumpTableSection().SectionIdx) &&
598 TEW->hasCustomJumpTableIndexRelTy()) {
599 RelType = TEW->getJumpTableIndexRelTy();
600 RelTySize = TEW->getRelocationTySize(RelType);
604 // The target without addend on the relocation symbol must be
605 // patched in the relocation place itself to contain the addend
607 RelocateField(S, RelOffset, Addend, RelTySize);
609 // Get the relocation entry and emit to the relocation section
610 ELFRelocation Rel(RelOffset, SymIdx, RelType, HasRelA, Addend);
611 EmitRelocation(RelSec, Rel, HasRelA);
616 /// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
617 void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
619 RelSec.emitWord(Rel.getOffset());
620 RelSec.emitWord(Rel.getInfo(is64Bit));
622 RelSec.emitWord(Rel.getAddend());
625 /// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
626 void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
628 SymbolTable.emitWord32(Sym.NameIdx);
629 SymbolTable.emitByte(Sym.Info);
630 SymbolTable.emitByte(Sym.Other);
631 SymbolTable.emitWord16(Sym.SectionIdx);
632 SymbolTable.emitWord64(Sym.Value);
633 SymbolTable.emitWord64(Sym.Size);
635 SymbolTable.emitWord32(Sym.NameIdx);
636 SymbolTable.emitWord32(Sym.Value);
637 SymbolTable.emitWord32(Sym.Size);
638 SymbolTable.emitByte(Sym.Info);
639 SymbolTable.emitByte(Sym.Other);
640 SymbolTable.emitWord16(Sym.SectionIdx);
644 /// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
645 /// Section Header Table
646 void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
647 const ELFSection &SHdr) {
648 SHdrTab.emitWord32(SHdr.NameIdx);
649 SHdrTab.emitWord32(SHdr.Type);
651 SHdrTab.emitWord64(SHdr.Flags);
652 SHdrTab.emitWord(SHdr.Addr);
653 SHdrTab.emitWord(SHdr.Offset);
654 SHdrTab.emitWord64(SHdr.Size);
655 SHdrTab.emitWord32(SHdr.Link);
656 SHdrTab.emitWord32(SHdr.Info);
657 SHdrTab.emitWord64(SHdr.Align);
658 SHdrTab.emitWord64(SHdr.EntSize);
660 SHdrTab.emitWord32(SHdr.Flags);
661 SHdrTab.emitWord(SHdr.Addr);
662 SHdrTab.emitWord(SHdr.Offset);
663 SHdrTab.emitWord32(SHdr.Size);
664 SHdrTab.emitWord32(SHdr.Link);
665 SHdrTab.emitWord32(SHdr.Info);
666 SHdrTab.emitWord32(SHdr.Align);
667 SHdrTab.emitWord32(SHdr.EntSize);
671 /// EmitStringTable - If the current symbol table is non-empty, emit the string
673 void ELFWriter::EmitStringTable() {
674 if (!SymbolList.size()) return; // Empty symbol table.
675 ELFSection &StrTab = getStringTableSection();
677 // Set the zero'th symbol to a null byte, as required.
680 // Walk on the symbol list and write symbol names into the string table.
682 for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
685 // Use the name mangler to uniquify the LLVM symbol.
687 if (Sym.GV) Name.append(Mang->getMangledName(Sym.GV));
693 StrTab.emitString(Name);
695 // Keep track of the number of bytes emitted to this section.
696 Index += Name.size()+1;
699 assert(Index == StrTab.size());
703 // SortSymbols - On the symbol table local symbols must come before
704 // all other symbols with non-local bindings. The return value is
705 // the position of the first non local symbol.
706 unsigned ELFWriter::SortSymbols() {
707 unsigned FirstNonLocalSymbol;
708 std::vector<ELFSym*> LocalSyms, OtherSyms;
710 for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
711 if ((*I)->isLocalBind())
712 LocalSyms.push_back(*I);
714 OtherSyms.push_back(*I);
717 FirstNonLocalSymbol = LocalSyms.size();
719 for (unsigned i = 0; i < FirstNonLocalSymbol; ++i)
720 SymbolList.push_back(LocalSyms[i]);
722 for (ELFSymIter I=OtherSyms.begin(), E=OtherSyms.end(); I != E; ++I)
723 SymbolList.push_back(*I);
728 return FirstNonLocalSymbol;
731 /// EmitSymbolTable - Emit the symbol table itself.
732 void ELFWriter::EmitSymbolTable() {
733 if (!SymbolList.size()) return; // Empty symbol table.
735 // Now that we have emitted the string table and know the offset into the
736 // string table of each symbol, emit the symbol table itself.
737 ELFSection &SymTab = getSymbolTableSection();
738 SymTab.Align = TEW->getPrefELFAlignment();
740 // Section Index of .strtab.
741 SymTab.Link = getStringTableSection().SectionIdx;
743 // Size of each symtab entry.
744 SymTab.EntSize = TEW->getSymTabEntrySize();
746 // The first entry in the symtab is the null symbol
747 SymbolList.insert(SymbolList.begin(), new ELFSym(0));
749 // Reorder the symbol table with local symbols first!
750 unsigned FirstNonLocalSymbol = SortSymbols();
752 // Emit all the symbols to the symbol table.
753 for (unsigned i = 0, e = SymbolList.size(); i < e; ++i) {
754 ELFSym &Sym = *SymbolList[i];
756 // Emit symbol to the symbol table
757 EmitSymbol(SymTab, Sym);
759 // Record the symbol table index for each global value
760 if (Sym.GV) setGlobalSymLookup(Sym.GV, i);
762 // Keep track on the symbol index into the symbol table
766 // One greater than the symbol table index of the last local symbol
767 SymTab.Info = FirstNonLocalSymbol;
768 SymTab.Size = SymTab.size();
771 /// EmitSectionTableStringTable - This method adds and emits a section for the
772 /// ELF Section Table string table: the string table that holds all of the
774 void ELFWriter::EmitSectionTableStringTable() {
775 // First step: add the section for the string table to the list of sections:
776 ELFSection &SHStrTab = getSectionHeaderStringTableSection();
778 // Now that we know which section number is the .shstrtab section, update the
779 // e_shstrndx entry in the ELF header.
780 ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
782 // Set the NameIdx of each section in the string table and emit the bytes for
786 for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
787 ELFSection &S = *(*I);
788 // Set the index into the table. Note if we have lots of entries with
789 // common suffixes, we could memoize them here if we cared.
791 SHStrTab.emitString(S.getName());
793 // Keep track of the number of bytes emitted to this section.
794 Index += S.getName().size()+1;
797 // Set the size of .shstrtab now that we know what it is.
798 assert(Index == SHStrTab.size());
799 SHStrTab.Size = Index;
802 /// OutputSectionsAndSectionTable - Now that we have constructed the file header
803 /// and all of the sections, emit these to the ostream destination and emit the
805 void ELFWriter::OutputSectionsAndSectionTable() {
806 // Pass #1: Compute the file offset for each section.
807 size_t FileOff = ElfHdr.size(); // File header first.
809 // Adjust alignment of all section if needed, skip the null section.
810 for (unsigned i=1, e=SectionList.size(); i < e; ++i) {
811 ELFSection &ES = *SectionList[i];
817 // Update Section size
821 // Align FileOff to whatever the alignment restrictions of the section are.
823 FileOff = (FileOff+ES.Align-1) & ~(ES.Align-1);
829 // Align Section Header.
830 unsigned TableAlign = TEW->getPrefELFAlignment();
831 FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
833 // Now that we know where all of the sections will be emitted, set the e_shnum
834 // entry in the ELF header.
835 ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
837 // Now that we know the offset in the file of the section table, update the
838 // e_shoff address in the ELF header.
839 ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
841 // Now that we know all of the data in the file header, emit it and all of the
843 O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
844 FileOff = ElfHdr.size();
846 // Section Header Table blob
847 BinaryObject SHdrTable(isLittleEndian, is64Bit);
849 // Emit all of sections to the file and build the section header table.
850 for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
851 ELFSection &S = *(*I);
852 DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
853 << ", Size: " << S.Size << ", Offset: " << S.Offset
854 << ", SectionData Size: " << S.size() << "\n";
856 // Align FileOff to whatever the alignment restrictions of the section are.
859 for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
860 FileOff != NewFileOff; ++FileOff)
863 O.write((char *)&S.getData()[0], S.Size);
867 EmitSectionHeader(SHdrTable, S);
870 // Align output for the section table.
871 for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
872 FileOff != NewFileOff; ++FileOff)
875 // Emit the section table itself.
876 O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());