| //===- X86LDBackend.cpp ---------------------------------------------------===// |
| // |
| // The MCLinker Project |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "X86.h" |
| #include "X86ELFDynamic.h" |
| #include "X86LDBackend.h" |
| #include "X86RelocationFactory.h" |
| |
| #include <llvm/ADT/Triple.h> |
| #include <mcld/Support/MemoryRegion.h> |
| #include <mcld/Support/TargetRegistry.h> |
| #include <mcld/MC/MCLDInfo.h> |
| #include <mcld/MC/MCLDOutput.h> |
| #include <mcld/MC/MCLinker.h> |
| #include <mcld/LD/SectionMap.h> |
| #include <mcld/MC/MCRegionFragment.h> |
| |
| #include <cstring> |
| |
| using namespace mcld; |
| |
| X86GNULDBackend::X86GNULDBackend() |
| : m_pRelocFactory(NULL), |
| m_pGOT(NULL), |
| m_pPLT(NULL), |
| m_pRelDyn(NULL), |
| m_pRelPLT(NULL), |
| m_pDynamic(NULL) { |
| } |
| |
| X86GNULDBackend::~X86GNULDBackend() |
| { |
| if (NULL != m_pRelocFactory) |
| delete m_pRelocFactory; |
| if (NULL != m_pGOT) |
| delete m_pGOT; |
| if (NULL != m_pPLT) |
| delete m_pPLT; |
| if (NULL !=m_pRelDyn) |
| delete m_pRelDyn; |
| if (NULL != m_pRelPLT) |
| delete m_pRelPLT; |
| if (NULL != m_pDynamic) |
| delete m_pDynamic; |
| } |
| |
| RelocationFactory* X86GNULDBackend::getRelocFactory() |
| { |
| assert(NULL != m_pRelocFactory); |
| return m_pRelocFactory; |
| } |
| |
| bool X86GNULDBackend::initRelocFactory(const MCLinker& pLinker) |
| { |
| if (NULL == m_pRelocFactory) { |
| m_pRelocFactory = new X86RelocationFactory(1024, *this); |
| m_pRelocFactory->setLayout(pLinker.getLayout()); |
| } |
| return true; |
| } |
| |
| void X86GNULDBackend::doPreLayout(const Output& pOutput, |
| const MCLDInfo& pInfo, |
| MCLinker& pLinker) |
| { |
| // when building shared object, the .got section is needed |
| if(pOutput.type() == Output::DynObj && (NULL == m_pGOT)) |
| createX86GOT(pLinker, pOutput); |
| } |
| |
| void X86GNULDBackend::doPostLayout(const Output& pOutput, |
| const MCLDInfo& pInfo, |
| MCLinker& pLinker) |
| { |
| // emit program headers |
| if(pOutput.type() == Output::DynObj || pOutput.type() == Output::Exec) |
| emitProgramHdrs(pLinker.getLDInfo().output()); |
| } |
| |
| /// dynamic - the dynamic section of the target machine. |
| /// Use co-variant return type to return its own dynamic section. |
| X86ELFDynamic& X86GNULDBackend::dynamic() |
| { |
| if (NULL == m_pDynamic) |
| m_pDynamic = new X86ELFDynamic(*this); |
| |
| return *m_pDynamic; |
| } |
| |
| /// dynamic - the dynamic section of the target machine. |
| /// Use co-variant return type to return its own dynamic section. |
| const X86ELFDynamic& X86GNULDBackend::dynamic() const |
| { |
| assert( NULL != m_pDynamic); |
| return *m_pDynamic; |
| } |
| |
| void X86GNULDBackend::createX86GOT(MCLinker& pLinker, const Output& pOutput) |
| { |
| // get .got LDSection and create MCSectionData |
| ELFFileFormat* file_format = getOutputFormat(pOutput); |
| |
| LDSection& got = file_format->getGOT(); |
| m_pGOT = new X86GOT(got, pLinker.getOrCreateSectData(got)); |
| |
| // define symbol _GLOBAL_OFFSET_TABLE_ when .got create |
| if( m_pGOTSymbol != NULL ) { |
| pLinker.defineSymbol<MCLinker::Force, MCLinker::Unresolve>( |
| "_GLOBAL_OFFSET_TABLE_", |
| false, |
| ResolveInfo::Object, |
| ResolveInfo::Define, |
| ResolveInfo::Local, |
| 0x0, // size |
| 0x0, // value |
| pLinker.getLayout().getFragmentRef(*(m_pGOT->begin()), 0x0), |
| ResolveInfo::Hidden); |
| } |
| else { |
| m_pGOTSymbol = pLinker.defineSymbol<MCLinker::Force, MCLinker::Resolve>( |
| "_GLOBAL_OFFSET_TABLE_", |
| false, |
| ResolveInfo::Object, |
| ResolveInfo::Define, |
| ResolveInfo::Local, |
| 0x0, // size |
| 0x0, // value |
| pLinker.getLayout().getFragmentRef(*(m_pGOT->begin()), 0x0), |
| ResolveInfo::Hidden); |
| } |
| } |
| |
| void X86GNULDBackend::createX86PLTandRelPLT(MCLinker& pLinker, |
| const Output& pOutput) |
| { |
| ELFFileFormat* file_format = getOutputFormat(pOutput); |
| |
| LDSection& plt = file_format->getPLT(); |
| LDSection& relplt = file_format->getRelPlt(); |
| // create MCSectionData and X86PLT |
| m_pPLT = new X86PLT(plt, pLinker.getOrCreateSectData(plt), *m_pGOT, pOutput); |
| |
| // set info of .rel.plt to .plt |
| relplt.setLink(&plt); |
| // create MCSectionData and X86RelDynSection |
| m_pRelPLT = new OutputRelocSection(relplt, |
| pLinker.getOrCreateSectData(relplt), |
| 8); |
| } |
| |
| void X86GNULDBackend::createX86RelDyn(MCLinker& pLinker, |
| const Output& pOutput) |
| { |
| // get .rel.dyn LDSection and create MCSectionData |
| ELFFileFormat* file_format = getOutputFormat(pOutput); |
| |
| LDSection& reldyn = file_format->getRelDyn(); |
| // create MCSectionData and X86RelDynSection |
| m_pRelDyn = new OutputRelocSection(reldyn, |
| pLinker.getOrCreateSectData(reldyn), |
| 8); |
| } |
| |
| ELFFileFormat* X86GNULDBackend::getOutputFormat(const Output& pOutput) const |
| { |
| switch (pOutput.type()) { |
| case Output::DynObj: |
| return getDynObjFileFormat(); |
| case Output::Exec: |
| return getExecFileFormat(); |
| // FIXME: We do not support building .o now |
| case Output::Object: |
| default: |
| llvm::report_fatal_error(llvm::Twine("Unsupported output file format: ") + |
| llvm::Twine(pOutput.type())); |
| return NULL; |
| } |
| } |
| |
| bool X86GNULDBackend::isSymbolNeedsPLT(const ResolveInfo& pSym, |
| const MCLDInfo& pLDInfo, |
| const Output& pOutput) const |
| { |
| return((Output::DynObj == pOutput.type()) |
| &&(ResolveInfo::Function == pSym.type()) |
| &&(pSym.isDyn() || pSym.isUndef() || |
| isSymbolPreemptible(pSym, pLDInfo, pOutput)) |
| ); |
| } |
| |
| bool X86GNULDBackend::isSymbolNeedsDynRel(const ResolveInfo& pSym, |
| const Output& pOutput, |
| bool isAbsReloc) const |
| { |
| if(pSym.isUndef() && (pOutput.type()==Output::Exec)) |
| return false; |
| if(pSym.isAbsolute()) |
| return false; |
| if(pOutput.type()==Output::DynObj && isAbsReloc) |
| return true; |
| if(pSym.isDyn() || pSym.isUndef()) |
| return true; |
| |
| return false; |
| } |
| |
| bool X86GNULDBackend::isSymbolPreemptible(const ResolveInfo& pSym, |
| const MCLDInfo& pLDInfo, |
| const Output& pOutput) const |
| { |
| if(pSym.other() != ResolveInfo::Default) |
| return false; |
| |
| if(pOutput.type() != Output::DynObj) |
| return false; |
| |
| if(pLDInfo.options().Bsymbolic()) |
| return false; |
| |
| return true; |
| } |
| |
| void X86GNULDBackend::updateAddend(Relocation& pReloc, |
| const LDSymbol& pInputSym, |
| const Layout& pLayout) const |
| { |
| // Update value keep in addend if we meet a section symbol |
| if(pReloc.symInfo()->type() == ResolveInfo::Section) { |
| pReloc.setAddend(pLayout.getOutputOffset( |
| *pInputSym.fragRef()) + pReloc.addend()); |
| } |
| } |
| |
| void X86GNULDBackend::scanLocalReloc(Relocation& pReloc, |
| const LDSymbol& pInputSym, |
| MCLinker& pLinker, |
| const MCLDInfo& pLDInfo, |
| const Output& pOutput) |
| { |
| // rsym - The relocation target symbol |
| ResolveInfo* rsym = pReloc.symInfo(); |
| |
| updateAddend(pReloc, pInputSym, pLinker.getLayout()); |
| |
| switch(pReloc.type()){ |
| |
| case llvm::ELF::R_386_32: |
| // If buiding PIC object (shared library or PIC executable), |
| // a dynamic relocations with RELATIVE type to this location is needed. |
| // Reserve an entry in .rel.dyn |
| if(Output::DynObj == pOutput.type()) { |
| // create .rel.dyn section if not exist |
| if(NULL == m_pRelDyn) |
| createX86RelDyn(pLinker, pOutput); |
| m_pRelDyn->reserveEntry(*m_pRelocFactory); |
| // set Rel bit |
| rsym->setReserved(rsym->reserved() | ReserveRel); |
| } |
| return; |
| |
| case llvm::ELF::R_386_GOTOFF: |
| case llvm::ELF::R_386_GOTPC: |
| // A GOT section is needed |
| if(NULL == m_pGOT) |
| createX86GOT(pLinker, pOutput); |
| return; |
| |
| case llvm::ELF::R_386_PC32: |
| return; |
| |
| default: |
| llvm::report_fatal_error(llvm::Twine("unexpected reloc ") + |
| llvm::Twine((int) pReloc.type()) + |
| llvm::Twine(" in object file")); |
| break; |
| } // end switch |
| } |
| |
| void X86GNULDBackend::scanGlobalReloc(Relocation& pReloc, |
| const LDSymbol& pInputSym, |
| MCLinker& pLinker, |
| const MCLDInfo& pLDInfo, |
| const Output& pOutput) |
| { |
| // rsym - The relocation target symbol |
| ResolveInfo* rsym = pReloc.symInfo(); |
| |
| switch(pReloc.type()) { |
| case llvm::ELF::R_386_32: |
| // Absolute relocation type, symbol may needs PLT entry or |
| // dynamic relocation entry |
| if(isSymbolNeedsPLT(*rsym, pLDInfo, pOutput)) { |
| // create plt for this symbol if it does not have one |
| if(!(rsym->reserved() & ReservePLT)){ |
| // Create .got section if it dosen't exist |
| if(NULL == m_pGOT) |
| createX86GOT(pLinker, pOutput); |
| // create .plt and .rel.plt if not exist |
| if(NULL == m_pPLT) |
| createX86PLTandRelPLT(pLinker, pOutput); |
| // Symbol needs PLT entry, we need to reserve a PLT entry |
| // and the corresponding GOT and dynamic relocation entry |
| // in .got and .rel.plt. (GOT entry will be reserved simultaneously |
| // when calling X86PLT->reserveEntry()) |
| m_pPLT->reserveEntry(); |
| m_pRelPLT->reserveEntry(*m_pRelocFactory); |
| // set PLT bit |
| rsym->setReserved(rsym->reserved() | ReservePLT); |
| } |
| } |
| |
| if(isSymbolNeedsDynRel(*rsym, pOutput, true)) { |
| // symbol needs dynamic relocation entry, reserve an entry in .rel.dyn |
| // create .rel.dyn section if not exist |
| if(NULL == m_pRelDyn) |
| createX86RelDyn(pLinker, pOutput); |
| m_pRelDyn->reserveEntry(*m_pRelocFactory); |
| // set Rel bit |
| rsym->setReserved(rsym->reserved() | ReserveRel); |
| } |
| return; |
| |
| case llvm::ELF::R_386_GOTOFF: |
| case llvm::ELF::R_386_GOTPC: { |
| // A GOT section is needed |
| if(NULL == m_pGOT) |
| createX86GOT(pLinker, pOutput); |
| return; |
| } |
| |
| case llvm::ELF::R_386_PLT32: |
| // A PLT entry is needed when building shared library |
| |
| // return if we already create plt for this symbol |
| if(rsym->reserved() & ReservePLT) |
| return; |
| |
| // if symbol is defined in the ouput file and it's not |
| // preemptible, no need plt |
| if(rsym->isDefine() && !rsym->isDyn() && |
| !isSymbolPreemptible(*rsym, pLDInfo, pOutput)) { |
| return; |
| } |
| |
| // Create .got section if it dosen't exist |
| if(NULL == m_pGOT) |
| createX86GOT(pLinker, pOutput); |
| // create .plt and .rel.plt if not exist |
| if(NULL == m_pPLT) |
| createX86PLTandRelPLT(pLinker, pOutput); |
| // Symbol needs PLT entry, we need to reserve a PLT entry |
| // and the corresponding GOT and dynamic relocation entry |
| // in .got and .rel.plt. (GOT entry will be reserved simultaneously |
| // when calling X86PLT->reserveEntry()) |
| m_pPLT->reserveEntry(); |
| m_pRelPLT->reserveEntry(*m_pRelocFactory); |
| // set PLT bit |
| rsym->setReserved(rsym->reserved() | ReservePLT); |
| return; |
| |
| case llvm::ELF::R_386_GOT32: |
| // Symbol needs GOT entry, reserve entry in .got |
| // return if we already create GOT for this symbol |
| if(rsym->reserved() & (ReserveGOT | GOTRel)) |
| return; |
| if(NULL == m_pGOT) |
| createX86GOT(pLinker, pOutput); |
| m_pGOT->reserveEntry(); |
| // If building shared object or the symbol is undefined, a dynamic |
| // relocation is needed to relocate this GOT entry. Reserve an |
| // entry in .rel.dyn |
| if(Output::DynObj == pOutput.type() || rsym->isUndef() || rsym->isDyn()) { |
| // create .rel.dyn section if not exist |
| if(NULL == m_pRelDyn) |
| createX86RelDyn(pLinker, pOutput); |
| m_pRelDyn->reserveEntry(*m_pRelocFactory); |
| // set GOTRel bit |
| rsym->setReserved(rsym->reserved() | GOTRel); |
| return; |
| } |
| // set GOT bit |
| rsym->setReserved(rsym->reserved() | ReserveGOT); |
| return; |
| |
| case llvm::ELF::R_386_PC32: |
| // We allow R_386_PC32 only if it isn't preemptible. Otherwise |
| // we will generate writable text section in output. |
| if (!isSymbolPreemptible(*rsym, pLDInfo, pOutput)) |
| return; |
| |
| default: { |
| llvm::report_fatal_error(llvm::Twine("Unexpected reloc ") + |
| llvm::Twine((int) pReloc.type()) + |
| llvm::Twine(" in object file")); |
| break; |
| } |
| } // end switch |
| } |
| |
| void X86GNULDBackend::scanRelocation(Relocation& pReloc, |
| const LDSymbol& pInputSym, |
| MCLinker& pLinker, |
| const MCLDInfo& pLDInfo, |
| const Output& pOutput) |
| { |
| // rsym - The relocation target symbol |
| ResolveInfo* rsym = pReloc.symInfo(); |
| assert(NULL != rsym && "ResolveInfo of relocation not set while scanRelocation"); |
| |
| // Scan relocation type to determine if an GOT/PLT/Dynamic Relocation |
| // entries should be created. |
| // FIXME: Below judgements concern only .so is generated as output |
| // FIXME: Below judgements concren nothing about TLS related relocation |
| |
| // A refernece to symbol _GLOBAL_OFFSET_TABLE_ implies that a .got section |
| // is needed |
| if(NULL == m_pGOT && NULL != m_pGOTSymbol) { |
| if(rsym == m_pGOTSymbol->resolveInfo()) { |
| createX86GOT(pLinker, pOutput); |
| } |
| } |
| |
| // rsym is local |
| if(rsym->isLocal()) |
| scanLocalReloc(pReloc, pInputSym, pLinker, pLDInfo, pOutput); |
| |
| // rsym is external |
| else |
| scanGlobalReloc(pReloc, pInputSym ,pLinker, pLDInfo, pOutput); |
| |
| } |
| |
| uint64_t X86GNULDBackend::emitSectionData(const Output& pOutput, |
| const LDSection& pSection, |
| const MCLDInfo& pInfo, |
| MemoryRegion& pRegion) const |
| { |
| assert(pRegion.size() && "Size of MemoryRegion is zero!"); |
| |
| ELFFileFormat* FileFormat = getOutputFormat(pOutput); |
| assert(FileFormat && |
| "ELFFileFormat is NULL in X86GNULDBackend::emitSectionData!"); |
| |
| unsigned int EntrySize = 0; |
| uint64_t RegionSize = 0; |
| |
| if (&pSection == &(FileFormat->getPLT())) { |
| assert(m_pPLT && "emitSectionData failed, m_pPLT is NULL!"); |
| |
| unsigned char* buffer = pRegion.getBuffer(); |
| |
| m_pPLT->applyPLT0(); |
| m_pPLT->applyPLT1(); |
| |
| X86PLT::iterator it = m_pPLT->begin(); |
| unsigned int plt0_size = llvm::cast<X86PLT0>((*it)).getEntrySize(); |
| |
| memcpy(buffer, llvm::cast<X86PLT0>((*it)).getContent(), plt0_size); |
| RegionSize += plt0_size; |
| ++it; |
| |
| X86PLT1* plt1 = 0; |
| X86PLT::iterator ie = m_pPLT->end(); |
| while (it != ie) { |
| plt1 = &(llvm::cast<X86PLT1>(*it)); |
| EntrySize = plt1->getEntrySize(); |
| memcpy(buffer + RegionSize, plt1->getContent(), EntrySize); |
| RegionSize += EntrySize; |
| ++it; |
| } |
| } |
| |
| else if (&pSection == &(FileFormat->getGOT())) { |
| assert(m_pGOT && "emitSectionData failed, m_pGOT is NULL!"); |
| |
| m_pGOT->applyGOT0(FileFormat->getDynamic().addr()); |
| |
| uint32_t* buffer = reinterpret_cast<uint32_t*>(pRegion.getBuffer()); |
| |
| GOTEntry* got = 0; |
| EntrySize = m_pGOT->getEntrySize(); |
| |
| for (X86GOT::iterator it = m_pGOT->begin(), |
| ie = m_pGOT->end(); it != ie; ++it, ++buffer) { |
| got = &(llvm::cast<GOTEntry>((*it))); |
| *buffer = static_cast<uint32_t>(got->getContent()); |
| RegionSize += EntrySize; |
| } |
| } |
| |
| else |
| llvm::report_fatal_error("unsupported section name " |
| + pSection.name() + " !"); |
| |
| return RegionSize; |
| } |
| uint32_t X86GNULDBackend::machine() const |
| { |
| return llvm::ELF::EM_386; |
| } |
| |
| X86GOT& X86GNULDBackend::getGOT() |
| { |
| assert(NULL != m_pGOT); |
| return *m_pGOT; |
| } |
| |
| const X86GOT& X86GNULDBackend::getGOT() const |
| { |
| assert(NULL != m_pGOT); |
| return *m_pGOT; |
| } |
| |
| X86PLT& X86GNULDBackend::getPLT() |
| { |
| assert(NULL != m_pPLT && "PLT section not exist"); |
| return *m_pPLT; |
| } |
| |
| const X86PLT& X86GNULDBackend::getPLT() const |
| { |
| assert(NULL != m_pPLT && "PLT section not exist"); |
| return *m_pPLT; |
| } |
| |
| OutputRelocSection& X86GNULDBackend::getRelDyn() |
| { |
| assert(NULL != m_pRelDyn && ".rel.dyn section not exist"); |
| return *m_pRelDyn; |
| } |
| |
| const OutputRelocSection& X86GNULDBackend::getRelDyn() const |
| { |
| assert(NULL != m_pRelDyn && ".rel.dyn section not exist"); |
| return *m_pRelDyn; |
| } |
| |
| OutputRelocSection& X86GNULDBackend::getRelPLT() |
| { |
| assert(NULL != m_pRelPLT && ".rel.plt section not exist"); |
| return *m_pRelPLT; |
| } |
| |
| const OutputRelocSection& X86GNULDBackend::getRelPLT() const |
| { |
| assert(NULL != m_pRelPLT && ".rel.plt section not exist"); |
| return *m_pRelPLT; |
| } |
| |
| unsigned int |
| X86GNULDBackend::getTargetSectionOrder(const Output& pOutput, |
| const LDSection& pSectHdr) const |
| { |
| ELFFileFormat* file_format = getOutputFormat(pOutput); |
| |
| // FIXME: if command line option, "-z now", is given, we can let the order of |
| // .got and .got.plt be the same as RELRO sections |
| if (&pSectHdr == &file_format->getGOT()) |
| return SHO_RELRO_LAST; |
| |
| if (&pSectHdr == &file_format->getGOTPLT()) |
| return SHO_NON_RELRO_FIRST; |
| |
| if (&pSectHdr == &file_format->getPLT()) |
| return SHO_PLT; |
| |
| return SHO_UNDEFINED; |
| } |
| |
| unsigned int X86GNULDBackend::bitclass() const |
| { |
| return 32; |
| } |
| |
| bool X86GNULDBackend::initTargetSectionMap(SectionMap& pSectionMap) |
| { |
| return true; |
| } |
| |
| void X86GNULDBackend::initTargetSections(MCLinker& pLinker) |
| { |
| } |
| |
| void X86GNULDBackend::initTargetSymbols(MCLinker& pLinker) |
| { |
| // Define the symbol _GLOBAL_OFFSET_TABLE_ if there is a symbol with the |
| // same name in input |
| m_pGOTSymbol = pLinker.defineSymbol<MCLinker::AsRefered, MCLinker::Resolve>( |
| "_GLOBAL_OFFSET_TABLE_", |
| false, |
| ResolveInfo::Object, |
| ResolveInfo::Define, |
| ResolveInfo::Local, |
| 0x0, // size |
| 0x0, // value |
| NULL, // FragRef |
| ResolveInfo::Hidden); |
| } |
| |
| /// finalizeSymbol - finalize the symbol value |
| /// If the symbol's reserved field is not zero, MCLinker will call back this |
| /// function to ask the final value of the symbol |
| bool X86GNULDBackend::finalizeSymbol(LDSymbol& pSymbol) const |
| { |
| return false; |
| } |
| |
| /// allocateCommonSymbols - allocate common symbols in the corresponding |
| /// sections. |
| /// @refer Google gold linker: common.cc: 214 |
| bool |
| X86GNULDBackend::allocateCommonSymbols(const MCLDInfo& pInfo, MCLinker& pLinker) const |
| { |
| // SymbolCategory contains all symbols that must emit to the output files. |
| // We are not like Google gold linker, we don't remember symbols before symbol |
| // resolution. All symbols in SymbolCategory are already resolved. Therefore, we |
| // don't need to care about some symbols may be changed its category due to symbol |
| // resolution. |
| SymbolCategory& symbol_list = pLinker.getOutputSymbols(); |
| |
| if (symbol_list.emptyCommons() && symbol_list.emptyLocals()) |
| return true; |
| |
| // addralign := max value of all common symbols |
| uint64_t addralign = 0x0; |
| |
| // Due to the visibility, some common symbols may be forcefully local. |
| SymbolCategory::iterator com_sym, com_end = symbol_list.localEnd(); |
| for (com_sym = symbol_list.localBegin(); com_sym != com_end; ++com_sym) { |
| if (ResolveInfo::Common == (*com_sym)->desc()) { |
| if ((*com_sym)->value() > addralign) |
| addralign = (*com_sym)->value(); |
| } |
| } |
| |
| // global common symbols. |
| com_end = symbol_list.commonEnd(); |
| for (com_sym = symbol_list.commonBegin(); com_sym != com_end; ++com_sym) { |
| if ((*com_sym)->value() > addralign) |
| addralign = (*com_sym)->value(); |
| } |
| |
| // FIXME: If the order of common symbols is defined, then sort common symbols |
| // com_sym = symbol_list.commonBegin(); |
| // std::sort(com_sym, com_end, some kind of order); |
| |
| // get or create corresponding BSS LDSection |
| LDSection* bss_sect_hdr = NULL; |
| if (ResolveInfo::ThreadLocal == (*com_sym)->type()) { |
| bss_sect_hdr = &pLinker.getOrCreateOutputSectHdr( |
| ".tbss", |
| LDFileFormat::BSS, |
| llvm::ELF::SHT_NOBITS, |
| llvm::ELF::SHF_WRITE | llvm::ELF::SHF_ALLOC); |
| } |
| else { |
| bss_sect_hdr = &pLinker.getOrCreateOutputSectHdr(".bss", |
| LDFileFormat::BSS, |
| llvm::ELF::SHT_NOBITS, |
| llvm::ELF::SHF_WRITE | llvm::ELF::SHF_ALLOC); |
| } |
| |
| // get or create corresponding BSS MCSectionData |
| assert(NULL != bss_sect_hdr); |
| llvm::MCSectionData& bss_section = pLinker.getOrCreateSectData(*bss_sect_hdr); |
| |
| // allocate all common symbols |
| uint64_t offset = bss_sect_hdr->size(); |
| |
| // allocate all local common symbols |
| com_end = symbol_list.localEnd(); |
| for (com_sym = symbol_list.localBegin(); com_sym != com_end; ++com_sym) { |
| if (ResolveInfo::Common == (*com_sym)->desc()) { |
| // We have to reset the description of the symbol here. When doing |
| // incremental linking, the output relocatable object may have common |
| // symbols. Therefore, we can not treat common symbols as normal symbols |
| // when emitting the regular name pools. We must change the symbols' |
| // description here. |
| (*com_sym)->resolveInfo()->setDesc(ResolveInfo::Define); |
| llvm::MCFragment* frag = new llvm::MCFillFragment(0x0, 1, (*com_sym)->size()); |
| (*com_sym)->setFragmentRef(new MCFragmentRef(*frag, 0)); |
| uint64_t size = pLinker.getLayout().appendFragment(*frag, |
| bss_section, |
| (*com_sym)->value()); |
| offset += size; |
| } |
| } |
| |
| // allocate all global common symbols |
| com_end = symbol_list.commonEnd(); |
| for (com_sym = symbol_list.commonBegin(); com_sym != com_end; ++com_sym) { |
| // We have to reset the description of the symbol here. When doing |
| // incremental linking, the output relocatable object may have common |
| // symbols. Therefore, we can not treat common symbols as normal symbols |
| // when emitting the regular name pools. We must change the symbols' |
| // description here. |
| (*com_sym)->resolveInfo()->setDesc(ResolveInfo::Define); |
| llvm::MCFragment* frag = new llvm::MCFillFragment(0x0, 1, (*com_sym)->size()); |
| (*com_sym)->setFragmentRef(new MCFragmentRef(*frag, 0)); |
| uint64_t size = pLinker.getLayout().appendFragment(*frag, |
| bss_section, |
| (*com_sym)->value()); |
| offset += size; |
| } |
| |
| bss_sect_hdr->setSize(offset); |
| symbol_list.changeCommonsToGlobal(); |
| return true; |
| } |
| |
| namespace mcld { |
| |
| //===----------------------------------------------------------------------===// |
| /// createX86LDBackend - the help funtion to create corresponding X86LDBackend |
| /// |
| TargetLDBackend* createX86LDBackend(const llvm::Target& pTarget, |
| const std::string& pTriple) |
| { |
| Triple theTriple(pTriple); |
| if (theTriple.isOSDarwin()) { |
| assert(0 && "MachO linker is not supported yet"); |
| /** |
| return new X86MachOLDBackend(createX86MachOArchiveReader, |
| createX86MachOObjectReader, |
| createX86MachOObjectWriter); |
| **/ |
| } |
| if (theTriple.isOSWindows()) { |
| assert(0 && "COFF linker is not supported yet"); |
| /** |
| return new X86COFFLDBackend(createX86COFFArchiveReader, |
| createX86COFFObjectReader, |
| createX86COFFObjectWriter); |
| **/ |
| } |
| return new X86GNULDBackend(); |
| } |
| |
| } // namespace of mcld |
| |
| //============================= |
| // Force static initialization. |
| extern "C" void LLVMInitializeX86LDBackend() { |
| // Register the linker backend |
| mcld::TargetRegistry::RegisterTargetLDBackend(TheX86Target, createX86LDBackend); |
| } |
