| //===- ObjectLinker.cpp ---------------------------------------------------===// |
| // |
| // The MCLinker Project |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| #include <mcld/Object/ObjectLinker.h> |
| |
| #include <mcld/InputTree.h> |
| #include <mcld/IRBuilder.h> |
| #include <mcld/LinkerConfig.h> |
| #include <mcld/LinkerScript.h> |
| #include <mcld/Module.h> |
| #include <mcld/Fragment/Relocation.h> |
| #include <mcld/LD/Archive.h> |
| #include <mcld/LD/ArchiveReader.h> |
| #include <mcld/LD/BinaryReader.h> |
| #include <mcld/LD/BranchIslandFactory.h> |
| #include <mcld/LD/DynObjReader.h> |
| #include <mcld/LD/GarbageCollection.h> |
| #include <mcld/LD/GroupReader.h> |
| #include <mcld/LD/IdenticalCodeFolding.h> |
| #include <mcld/LD/LDContext.h> |
| #include <mcld/LD/LDSection.h> |
| #include <mcld/LD/ObjectReader.h> |
| #include <mcld/LD/ObjectWriter.h> |
| #include <mcld/LD/Relocator.h> |
| #include <mcld/LD/RelocData.h> |
| #include <mcld/LD/ResolveInfo.h> |
| #include <mcld/LD/SectionData.h> |
| #include <mcld/Object/ObjectBuilder.h> |
| #include <mcld/Script/Assignment.h> |
| #include <mcld/Script/Operand.h> |
| #include <mcld/Script/RpnEvaluator.h> |
| #include <mcld/Script/ScriptFile.h> |
| #include <mcld/Script/ScriptReader.h> |
| #include <mcld/Support/FileOutputBuffer.h> |
| #include <mcld/Support/MsgHandling.h> |
| #include <mcld/Support/RealPath.h> |
| #include <mcld/Target/TargetLDBackend.h> |
| |
| #include <llvm/Support/Casting.h> |
| #include <llvm/Support/Host.h> |
| |
| #include <system_error> |
| |
| namespace mcld { |
| |
| //===----------------------------------------------------------------------===// |
| // ObjectLinker |
| //===----------------------------------------------------------------------===// |
| ObjectLinker::ObjectLinker(const LinkerConfig& pConfig, |
| TargetLDBackend& pLDBackend) |
| : m_Config(pConfig), |
| m_pModule(NULL), |
| m_pBuilder(NULL), |
| m_LDBackend(pLDBackend), |
| m_pObjectReader(NULL), |
| m_pDynObjReader(NULL), |
| m_pArchiveReader(NULL), |
| m_pGroupReader(NULL), |
| m_pBinaryReader(NULL), |
| m_pScriptReader(NULL), |
| m_pWriter(NULL) { |
| } |
| |
| ObjectLinker::~ObjectLinker() { |
| delete m_pObjectReader; |
| delete m_pDynObjReader; |
| delete m_pArchiveReader; |
| delete m_pGroupReader; |
| delete m_pBinaryReader; |
| delete m_pScriptReader; |
| delete m_pWriter; |
| } |
| |
| bool ObjectLinker::initialize(Module& pModule, IRBuilder& pBuilder) { |
| m_pModule = &pModule; |
| m_pBuilder = &pBuilder; |
| |
| // initialize the readers and writers |
| m_pObjectReader = m_LDBackend.createObjectReader(*m_pBuilder); |
| m_pArchiveReader = m_LDBackend.createArchiveReader(*m_pModule); |
| m_pDynObjReader = m_LDBackend.createDynObjReader(*m_pBuilder); |
| m_pBinaryReader = m_LDBackend.createBinaryReader(*m_pBuilder); |
| m_pGroupReader = new GroupReader(*m_pModule, |
| *m_pObjectReader, |
| *m_pDynObjReader, |
| *m_pArchiveReader, |
| *m_pBinaryReader); |
| m_pScriptReader = new ScriptReader( |
| *m_pObjectReader, *m_pArchiveReader, *m_pDynObjReader, *m_pGroupReader); |
| m_pWriter = m_LDBackend.createWriter(); |
| |
| // initialize Relocator |
| m_LDBackend.initRelocator(); |
| |
| return true; |
| } |
| |
| /// initStdSections - initialize standard sections |
| bool ObjectLinker::initStdSections() { |
| ObjectBuilder builder(*m_pModule); |
| |
| // initialize standard sections |
| if (!m_LDBackend.initStdSections(builder)) |
| return false; |
| |
| // initialize target-dependent sections |
| m_LDBackend.initTargetSections(*m_pModule, builder); |
| |
| return true; |
| } |
| |
| void ObjectLinker::addUndefinedSymbols() { |
| // Add the symbol set by -u as an undefind global symbol into symbol pool |
| GeneralOptions::const_undef_sym_iterator usym; |
| GeneralOptions::const_undef_sym_iterator usymEnd = |
| m_Config.options().undef_sym_end(); |
| for (usym = m_Config.options().undef_sym_begin(); usym != usymEnd; ++usym) { |
| Resolver::Result result; |
| m_pModule->getNamePool().insertSymbol(*usym, // name |
| false, // isDyn |
| ResolveInfo::NoType, |
| ResolveInfo::Undefined, |
| ResolveInfo::Global, |
| 0x0, // size |
| 0x0, // value |
| ResolveInfo::Default, |
| NULL, |
| result); |
| |
| LDSymbol* output_sym = result.info->outSymbol(); |
| // create the output symbol if it dose not have one |
| if (!result.existent || (output_sym != NULL)) { |
| output_sym = LDSymbol::Create(*result.info); |
| result.info->setSymPtr(output_sym); |
| output_sym->setFragmentRef(FragmentRef::Null()); |
| } |
| } |
| } |
| |
| void ObjectLinker::normalize() { |
| // ----- set up inputs ----- // |
| Module::input_iterator input, inEnd = m_pModule->input_end(); |
| for (input = m_pModule->input_begin(); input != inEnd; ++input) { |
| // is a group node |
| if (isGroup(input)) { |
| getGroupReader()->readGroup( |
| input, inEnd, m_pBuilder->getInputBuilder(), m_Config); |
| continue; |
| } |
| |
| // already got type - for example, bitcode or external OIR (object |
| // intermediate representation) |
| if ((*input)->type() == Input::Script || |
| (*input)->type() == Input::Archive || |
| (*input)->type() == Input::External) |
| continue; |
| |
| if (Input::Object == (*input)->type()) { |
| m_pModule->getObjectList().push_back(*input); |
| continue; |
| } |
| |
| if (Input::DynObj == (*input)->type()) { |
| m_pModule->getLibraryList().push_back(*input); |
| continue; |
| } |
| |
| bool doContinue = false; |
| // read input as a binary file |
| if (getBinaryReader()->isMyFormat(**input, doContinue)) { |
| (*input)->setType(Input::Object); |
| getBinaryReader()->readBinary(**input); |
| m_pModule->getObjectList().push_back(*input); |
| } else if (doContinue && |
| getObjectReader()->isMyFormat(**input, doContinue)) { |
| // is a relocatable object file |
| (*input)->setType(Input::Object); |
| getObjectReader()->readHeader(**input); |
| getObjectReader()->readSections(**input); |
| getObjectReader()->readSymbols(**input); |
| m_pModule->getObjectList().push_back(*input); |
| } else if (doContinue && |
| getDynObjReader()->isMyFormat(**input, doContinue)) { |
| // is a shared object file |
| (*input)->setType(Input::DynObj); |
| getDynObjReader()->readHeader(**input); |
| getDynObjReader()->readSymbols(**input); |
| m_pModule->getLibraryList().push_back(*input); |
| } else if (doContinue && |
| getArchiveReader()->isMyFormat(**input, doContinue)) { |
| // is an archive |
| (*input)->setType(Input::Archive); |
| if (m_Config.options().isInExcludeLIBS(**input)) { |
| (*input)->setNoExport(); |
| } |
| Archive archive(**input, m_pBuilder->getInputBuilder()); |
| getArchiveReader()->readArchive(m_Config, archive); |
| if (archive.numOfObjectMember() > 0) { |
| m_pModule->getInputTree().merge<InputTree::Inclusive>(input, |
| archive.inputs()); |
| } |
| } else if (doContinue && |
| getScriptReader()->isMyFormat(**input, doContinue)) { |
| // try to parse input as a linker script |
| ScriptFile script( |
| ScriptFile::LDScript, **input, m_pBuilder->getInputBuilder()); |
| if (getScriptReader()->readScript(m_Config, script)) { |
| (*input)->setType(Input::Script); |
| script.activate(*m_pModule); |
| if (script.inputs().size() > 0) { |
| m_pModule->getInputTree().merge<InputTree::Inclusive>( |
| input, script.inputs()); |
| } |
| } |
| } else { |
| if (m_Config.options().warnMismatch()) |
| warning(diag::warn_unrecognized_input_file) |
| << (*input)->path() << m_Config.targets().triple().str(); |
| } |
| } // end of for |
| } |
| |
| bool ObjectLinker::linkable() const { |
| // check we have input and output files |
| if (m_pModule->getInputTree().empty()) { |
| error(diag::err_no_inputs); |
| return false; |
| } |
| |
| // can not mix -static with shared objects |
| Module::const_lib_iterator lib, libEnd = m_pModule->lib_end(); |
| for (lib = m_pModule->lib_begin(); lib != libEnd; ++lib) { |
| if ((*lib)->attribute()->isStatic()) { |
| error(diag::err_mixed_shared_static_objects) << (*lib)->name() |
| << (*lib)->path(); |
| return false; |
| } |
| } |
| |
| // --nmagic and --omagic options lead to static executable program. |
| // These options turn off page alignment of sections. Because the |
| // sections are not aligned to pages, these sections can not contain any |
| // exported functions. Also, because the two options disable linking |
| // against shared libraries, the output absolutely does not call outside |
| // functions. |
| if (m_Config.options().nmagic() && !m_Config.isCodeStatic()) { |
| error(diag::err_nmagic_not_static); |
| return false; |
| } |
| if (m_Config.options().omagic() && !m_Config.isCodeStatic()) { |
| error(diag::err_omagic_not_static); |
| return false; |
| } |
| |
| return true; |
| } |
| |
| void ObjectLinker::dataStrippingOpt() { |
| // Garbege collection |
| if (m_Config.options().GCSections()) { |
| GarbageCollection GC(m_Config, m_LDBackend, *m_pModule); |
| GC.run(); |
| } |
| |
| // Identical code folding |
| if (m_Config.options().getICFMode() != GeneralOptions::ICF_None) { |
| IdenticalCodeFolding icf(m_Config, m_LDBackend, *m_pModule); |
| icf.foldIdenticalCode(); |
| } |
| return; |
| } |
| |
| /// readRelocations - read all relocation entries |
| /// |
| /// All symbols should be read and resolved before this function. |
| bool ObjectLinker::readRelocations() { |
| // Bitcode is read by the other path. This function reads relocation sections |
| // in object files. |
| mcld::InputTree::bfs_iterator input, |
| inEnd = m_pModule->getInputTree().bfs_end(); |
| for (input = m_pModule->getInputTree().bfs_begin(); input != inEnd; ++input) { |
| if ((*input)->type() == Input::Object && (*input)->hasMemArea()) { |
| if (!getObjectReader()->readRelocations(**input)) |
| return false; |
| } |
| // ignore the other kinds of files. |
| } |
| return true; |
| } |
| |
| /// mergeSections - put allinput sections into output sections |
| bool ObjectLinker::mergeSections() { |
| // Set up input/output from ldscript requirement if any |
| { |
| RpnEvaluator evaluator(*m_pModule, m_LDBackend); |
| SectionMap::iterator out, outBegin, outEnd; |
| outBegin = m_pModule->getScript().sectionMap().begin(); |
| outEnd = m_pModule->getScript().sectionMap().end(); |
| for (out = outBegin; out != outEnd; ++out) { |
| uint64_t out_align = 0x0, in_align = 0x0; |
| LDSection* out_sect = (*out)->getSection(); |
| SectionMap::Output::iterator in, inBegin, inEnd; |
| inBegin = (*out)->begin(); |
| inEnd = (*out)->end(); |
| |
| // force input alignment from ldscript if any |
| if ((*out)->prolog().hasSubAlign()) { |
| evaluator.eval((*out)->prolog().subAlign(), in_align); |
| } |
| |
| for (in = inBegin; in != inEnd; ++in) { |
| LDSection* in_sect = (*in)->getSection(); |
| if ((*out)->prolog().hasSubAlign()) |
| in_sect->setAlign(in_align); |
| } // for each input section description |
| |
| // force output alignment from ldscript if any |
| if ((*out)->prolog().hasAlign()) { |
| evaluator.eval((*out)->prolog().align(), out_align); |
| out_sect->setAlign(out_align); |
| } |
| } // for each output section description |
| } |
| |
| ObjectBuilder builder(*m_pModule); |
| Module::obj_iterator obj, objEnd = m_pModule->obj_end(); |
| for (obj = m_pModule->obj_begin(); obj != objEnd; ++obj) { |
| LDContext::sect_iterator sect, sectEnd = (*obj)->context()->sectEnd(); |
| for (sect = (*obj)->context()->sectBegin(); sect != sectEnd; ++sect) { |
| switch ((*sect)->kind()) { |
| // Some *INPUT sections should not be merged. |
| case LDFileFormat::Folded: |
| case LDFileFormat::Ignore: |
| case LDFileFormat::Null: |
| case LDFileFormat::NamePool: |
| case LDFileFormat::Group: |
| case LDFileFormat::StackNote: |
| // skip |
| continue; |
| case LDFileFormat::Relocation: { |
| if (!(*sect)->hasRelocData()) |
| continue; // skip |
| |
| if ((*sect)->getLink()->kind() == LDFileFormat::Ignore || |
| (*sect)->getLink()->kind() == LDFileFormat::Folded) { |
| (*sect)->setKind(LDFileFormat::Ignore); |
| break; |
| } |
| |
| // process the relocation which may refer to .debug_str |
| if ((*sect)->getLink()->kind() == LDFileFormat::Debug) |
| m_pModule->getDebugString().processRelocs(**sect, m_LDBackend); |
| break; |
| } |
| case LDFileFormat::Target: |
| if (!m_LDBackend.mergeSection(*m_pModule, **obj, **sect)) { |
| error(diag::err_cannot_merge_section) << (*sect)->name() |
| << (*obj)->name(); |
| return false; |
| } |
| break; |
| case LDFileFormat::EhFrame: { |
| if (!(*sect)->hasEhFrame()) |
| continue; // skip |
| |
| LDSection* out_sect = NULL; |
| if ((out_sect = builder.MergeSection(**obj, **sect)) != NULL) { |
| if (!m_LDBackend.updateSectionFlags(*out_sect, **sect)) { |
| error(diag::err_cannot_merge_section) << (*sect)->name() |
| << (*obj)->name(); |
| return false; |
| } |
| } |
| break; |
| } |
| default: { |
| if (!(*sect)->hasSectionData()) |
| continue; // skip |
| |
| LDSection* out_sect = NULL; |
| if ((out_sect = builder.MergeSection(**obj, **sect)) != NULL) { |
| if (!m_LDBackend.updateSectionFlags(*out_sect, **sect)) { |
| error(diag::err_cannot_merge_section) << (*sect)->name() |
| << (*obj)->name(); |
| return false; |
| } |
| } |
| break; |
| } |
| } // end of switch |
| } // for each section |
| } // for each obj |
| |
| { |
| SectionMap::iterator out, outBegin, outEnd; |
| outBegin = m_pModule->getScript().sectionMap().begin(); |
| outEnd = m_pModule->getScript().sectionMap().end(); |
| for (out = outBegin; out != outEnd; ++out) { |
| LDSection* out_sect = (*out)->getSection(); |
| SectionMap::Output::iterator in, inBegin, inEnd; |
| inBegin = (*out)->begin(); |
| inEnd = (*out)->end(); |
| |
| for (in = inBegin; in != inEnd; ++in) { |
| LDSection* in_sect = (*in)->getSection(); |
| if (builder.MoveSectionData(*in_sect->getSectionData(), |
| *out_sect->getSectionData())) { |
| builder.UpdateSectionAlign(*out_sect, *in_sect); |
| m_LDBackend.updateSectionFlags(*out_sect, *in_sect); |
| } |
| } // for each input section description |
| |
| if ((*out)->hasContent()) { |
| LDSection* target = m_pModule->getSection((*out)->name()); |
| assert(target != NULL && target->hasSectionData()); |
| if (builder.MoveSectionData(*out_sect->getSectionData(), |
| *target->getSectionData())) { |
| builder.UpdateSectionAlign(*target, *out_sect); |
| m_LDBackend.updateSectionFlags(*target, *out_sect); |
| } |
| } |
| } // for each output section description |
| } |
| |
| return true; |
| } |
| |
| void ObjectLinker::addSymbolToOutput(ResolveInfo& pInfo, Module& pModule) { |
| // section symbols will be defined by linker later, we should not add section |
| // symbols to output here |
| if (ResolveInfo::Section == pInfo.type() || pInfo.outSymbol() == NULL) |
| return; |
| |
| // if the symbols defined in the Ignore sections (e.g. discared by GC), then |
| // not to put them to output |
| if (pInfo.outSymbol()->hasFragRef() && |
| LDFileFormat::Ignore == |
| pInfo.outSymbol() |
| ->fragRef() |
| ->frag() |
| ->getParent() |
| ->getSection() |
| .kind()) |
| return; |
| |
| if (pInfo.shouldForceLocal(m_Config)) |
| pModule.getSymbolTable().forceLocal(*pInfo.outSymbol()); |
| else |
| pModule.getSymbolTable().add(*pInfo.outSymbol()); |
| } |
| |
| void ObjectLinker::addSymbolsToOutput(Module& pModule) { |
| // Traverse all the free ResolveInfo and add the output symobols to output |
| NamePool::freeinfo_iterator free_it, |
| free_end = pModule.getNamePool().freeinfo_end(); |
| for (free_it = pModule.getNamePool().freeinfo_begin(); free_it != free_end; |
| ++free_it) |
| addSymbolToOutput(**free_it, pModule); |
| |
| // Traverse all the resolveInfo and add the output symbol to output |
| NamePool::syminfo_iterator info_it, |
| info_end = pModule.getNamePool().syminfo_end(); |
| for (info_it = pModule.getNamePool().syminfo_begin(); info_it != info_end; |
| ++info_it) |
| addSymbolToOutput(*info_it.getEntry(), pModule); |
| } |
| |
| /// addStandardSymbols - shared object and executable files need some |
| /// standard symbols |
| /// @return if there are some input symbols with the same name to the |
| /// standard symbols, return false |
| bool ObjectLinker::addStandardSymbols() { |
| // create and add section symbols for each output section |
| Module::iterator iter, iterEnd = m_pModule->end(); |
| for (iter = m_pModule->begin(); iter != iterEnd; ++iter) { |
| m_pModule->getSectionSymbolSet().add(**iter, m_pModule->getNamePool()); |
| } |
| |
| return m_LDBackend.initStandardSymbols(*m_pBuilder, *m_pModule); |
| } |
| |
| /// addTargetSymbols - some targets, such as MIPS and ARM, need some |
| /// target-dependent symbols |
| /// @return if there are some input symbols with the same name to the |
| /// target symbols, return false |
| bool ObjectLinker::addTargetSymbols() { |
| m_LDBackend.initTargetSymbols(*m_pBuilder, *m_pModule); |
| return true; |
| } |
| |
| /// addScriptSymbols - define symbols from the command line option or linker |
| /// scripts. |
| bool ObjectLinker::addScriptSymbols() { |
| LinkerScript& script = m_pModule->getScript(); |
| LinkerScript::Assignments::iterator it, ie = script.assignments().end(); |
| // go through the entire symbol assignments |
| for (it = script.assignments().begin(); it != ie; ++it) { |
| LDSymbol* symbol = NULL; |
| assert((*it).second.symbol().type() == Operand::SYMBOL); |
| const llvm::StringRef symName = (*it).second.symbol().name(); |
| ResolveInfo::Type type = ResolveInfo::NoType; |
| ResolveInfo::Visibility vis = ResolveInfo::Default; |
| size_t size = 0; |
| ResolveInfo* old_info = m_pModule->getNamePool().findInfo(symName); |
| // if the symbol does not exist, we can set type to NOTYPE |
| // else we retain its type, same goes for size - 0 or retain old value |
| // and visibility - Default or retain |
| if (old_info != NULL) { |
| type = static_cast<ResolveInfo::Type>(old_info->type()); |
| vis = old_info->visibility(); |
| size = old_info->size(); |
| } |
| |
| // Add symbol and refine the visibility if needed |
| // FIXME: bfd linker would change the binding instead, but currently |
| // ABS is also a kind of Binding in ResolveInfo. |
| switch ((*it).second.type()) { |
| case Assignment::HIDDEN: |
| vis = ResolveInfo::Hidden; |
| // Fall through |
| case Assignment::DEFAULT: |
| symbol = m_pBuilder->AddSymbol<IRBuilder::Force, IRBuilder::Unresolve>( |
| symName, |
| type, |
| ResolveInfo::Define, |
| ResolveInfo::Absolute, |
| size, |
| 0x0, |
| FragmentRef::Null(), |
| vis); |
| break; |
| case Assignment::PROVIDE_HIDDEN: |
| vis = ResolveInfo::Hidden; |
| // Fall through |
| case Assignment::PROVIDE: |
| symbol = |
| m_pBuilder->AddSymbol<IRBuilder::AsReferred, IRBuilder::Unresolve>( |
| symName, |
| type, |
| ResolveInfo::Define, |
| ResolveInfo::Absolute, |
| size, |
| 0x0, |
| FragmentRef::Null(), |
| vis); |
| break; |
| } |
| // Set symbol of this assignment. |
| (*it).first = symbol; |
| } |
| return true; |
| } |
| |
| bool ObjectLinker::scanRelocations() { |
| // apply all relocations of all inputs |
| Module::obj_iterator input, inEnd = m_pModule->obj_end(); |
| for (input = m_pModule->obj_begin(); input != inEnd; ++input) { |
| m_LDBackend.getRelocator()->initializeScan(**input); |
| LDContext::sect_iterator rs, rsEnd = (*input)->context()->relocSectEnd(); |
| for (rs = (*input)->context()->relocSectBegin(); rs != rsEnd; ++rs) { |
| // bypass the reloc section if |
| // 1. its section kind is changed to Ignore. (The target section is a |
| // discarded group section.) |
| // 2. it has no reloc data. (All symbols in the input relocs are in the |
| // discarded group sections) |
| if (LDFileFormat::Ignore == (*rs)->kind() || !(*rs)->hasRelocData()) |
| continue; |
| RelocData::iterator reloc, rEnd = (*rs)->getRelocData()->end(); |
| for (reloc = (*rs)->getRelocData()->begin(); reloc != rEnd; ++reloc) { |
| Relocation* relocation = llvm::cast<Relocation>(reloc); |
| |
| // bypass the reloc if the symbol is in the discarded input section |
| ResolveInfo* info = relocation->symInfo(); |
| if (!info->outSymbol()->hasFragRef() && |
| ResolveInfo::Section == info->type() && |
| ResolveInfo::Undefined == info->desc()) |
| continue; |
| |
| // scan relocation |
| if (LinkerConfig::Object != m_Config.codeGenType()) { |
| m_LDBackend.getRelocator()->scanRelocation( |
| *relocation, *m_pBuilder, *m_pModule, **rs, **input); |
| } else { |
| m_LDBackend.getRelocator()->partialScanRelocation( |
| *relocation, *m_pModule, **rs); |
| } |
| } // for all relocations |
| } // for all relocation section |
| m_LDBackend.getRelocator()->finalizeScan(**input); |
| } // for all inputs |
| return true; |
| } |
| |
| /// initStubs - initialize stub-related stuff. |
| bool ObjectLinker::initStubs() { |
| // initialize BranchIslandFactory |
| m_LDBackend.initBRIslandFactory(); |
| |
| // initialize StubFactory |
| m_LDBackend.initStubFactory(); |
| |
| // initialize target stubs |
| m_LDBackend.initTargetStubs(); |
| return true; |
| } |
| |
| /// allocateCommonSymobols - allocate fragments for common symbols to the |
| /// corresponding sections |
| bool ObjectLinker::allocateCommonSymbols() { |
| if (LinkerConfig::Object != m_Config.codeGenType() || |
| m_Config.options().isDefineCommon()) |
| return m_LDBackend.allocateCommonSymbols(*m_pModule); |
| return true; |
| } |
| |
| /// prelayout - help backend to do some modification before layout |
| bool ObjectLinker::prelayout() { |
| // finalize the section symbols, set their fragment reference and push them |
| // into output symbol table |
| Module::iterator sect, sEnd = m_pModule->end(); |
| for (sect = m_pModule->begin(); sect != sEnd; ++sect) { |
| m_pModule->getSectionSymbolSet().finalize( |
| **sect, |
| m_pModule->getSymbolTable(), |
| m_Config.codeGenType() == LinkerConfig::Object); |
| } |
| |
| m_LDBackend.preLayout(*m_pModule, *m_pBuilder); |
| |
| /// check program interpreter - computer the name size of the runtime dyld |
| if (!m_Config.isCodeStatic() && |
| (LinkerConfig::Exec == m_Config.codeGenType() || |
| m_Config.options().isPIE() || m_Config.options().hasDyld())) |
| m_LDBackend.sizeInterp(); |
| |
| /// measure NamePools - compute the size of name pool sections |
| /// In ELF, will compute the size of.symtab, .strtab, .dynsym, .dynstr, |
| /// .hash and .shstrtab sections. |
| /// |
| /// dump all symbols and strings from ObjectLinker and build the |
| /// format-dependent |
| /// hash table. |
| /// @note sizeNamePools replies on LinkerConfig::CodePosition. Must determine |
| /// code position model before calling GNULDBackend::sizeNamePools() |
| m_LDBackend.sizeNamePools(*m_pModule); |
| |
| // Do this after backend prelayout since it may add eh_frame entries. |
| LDSection* eh_frame_sect = m_pModule->getSection(".eh_frame"); |
| if (eh_frame_sect && eh_frame_sect->hasEhFrame()) |
| eh_frame_sect->getEhFrame()->computeOffsetSize(); |
| m_LDBackend.createAndSizeEhFrameHdr(*m_pModule); |
| |
| // size debug string table |
| // we set the .debug_str size here so that there won't be a section symbol for |
| // .debug_str. While actually it doesn't matter that .debug_str has section |
| // symbol or not. |
| if (m_pModule->getDebugString().isSuccess()) |
| m_pModule->getDebugString().sizeStringTable(); |
| |
| return true; |
| } |
| |
| /// layout - linearly layout all output sections and reserve some space |
| /// for GOT/PLT |
| /// Because we do not support instruction relaxing in this early version, |
| /// if there is a branch can not jump to its target, we return false |
| /// directly |
| bool ObjectLinker::layout() { |
| m_LDBackend.layout(*m_pModule); |
| return true; |
| } |
| |
| /// prelayout - help backend to do some modification after layout |
| bool ObjectLinker::postlayout() { |
| m_LDBackend.postLayout(*m_pModule, *m_pBuilder); |
| return true; |
| } |
| |
| /// finalizeSymbolValue - finalize the resolved symbol value. |
| /// Before relocate(), after layout(), ObjectLinker should correct value of |
| /// all |
| /// symbol. |
| bool ObjectLinker::finalizeSymbolValue() { |
| Module::sym_iterator symbol, symEnd = m_pModule->sym_end(); |
| for (symbol = m_pModule->sym_begin(); symbol != symEnd; ++symbol) { |
| if ((*symbol)->resolveInfo()->isAbsolute() || |
| (*symbol)->resolveInfo()->type() == ResolveInfo::File) { |
| // absolute symbols should just use its value directly (i.e., the result |
| // of symbol resolution) |
| continue; |
| } |
| |
| if ((*symbol)->resolveInfo()->type() == ResolveInfo::ThreadLocal) { |
| m_LDBackend.finalizeTLSSymbol(**symbol); |
| continue; |
| } |
| |
| if ((*symbol)->hasFragRef()) { |
| // set the virtual address of the symbol. If the output file is |
| // relocatable object file, the section's virtual address becomes zero. |
| // And the symbol's value become section relative offset. |
| uint64_t value = (*symbol)->fragRef()->getOutputOffset(); |
| assert((*symbol)->fragRef()->frag() != NULL); |
| uint64_t addr = |
| (*symbol)->fragRef()->frag()->getParent()->getSection().addr(); |
| (*symbol)->setValue(value + addr); |
| continue; |
| } |
| } |
| |
| RpnEvaluator evaluator(*m_pModule, m_LDBackend); |
| bool finalized = m_LDBackend.finalizeSymbols(); |
| bool scriptSymsFinalized = true; |
| LinkerScript& script = m_pModule->getScript(); |
| LinkerScript::Assignments::iterator assign, assignEnd; |
| assignEnd = script.assignments().end(); |
| for (assign = script.assignments().begin(); assign != assignEnd; ++assign) { |
| LDSymbol* symbol = (*assign).first; |
| Assignment& assignment = (*assign).second; |
| |
| if (symbol == NULL) |
| continue; |
| |
| scriptSymsFinalized &= assignment.assign(evaluator); |
| if (!scriptSymsFinalized) |
| break; |
| |
| symbol->setValue(assignment.symbol().value()); |
| } // for each script symbol assignment |
| |
| bool assertionsPassed = true; |
| LinkerScript::Assertions::iterator assert, assertEnd; |
| assertEnd = script.assertions().end(); |
| for (assert = script.assertions().begin(); assert != assertEnd; ++assert) { |
| uint64_t res = 0x0; |
| evaluator.eval((*assert).getRpnExpr(), res); |
| if (res == 0x0) |
| fatal(diag::err_assert_failed) << (*assert).message(); |
| } // for each assertion in ldscript |
| |
| return finalized && scriptSymsFinalized && assertionsPassed; |
| } |
| |
| /// relocate - applying relocation entries and create relocation |
| /// section in the output files |
| /// Create relocation section, asking TargetLDBackend to |
| /// read the relocation information into RelocationEntry |
| /// and push_back into the relocation section |
| bool ObjectLinker::relocation() { |
| // when producing relocatables, no need to apply relocation |
| if (LinkerConfig::Object == m_Config.codeGenType()) |
| return true; |
| |
| // apply all relocations of all inputs |
| Module::obj_iterator input, inEnd = m_pModule->obj_end(); |
| for (input = m_pModule->obj_begin(); input != inEnd; ++input) { |
| m_LDBackend.getRelocator()->initializeApply(**input); |
| LDContext::sect_iterator rs, rsEnd = (*input)->context()->relocSectEnd(); |
| for (rs = (*input)->context()->relocSectBegin(); rs != rsEnd; ++rs) { |
| // bypass the reloc section if |
| // 1. its section kind is changed to Ignore. (The target section is a |
| // discarded group section.) |
| // 2. it has no reloc data. (All symbols in the input relocs are in the |
| // discarded group sections) |
| if (LDFileFormat::Ignore == (*rs)->kind() || !(*rs)->hasRelocData()) |
| continue; |
| RelocData::iterator reloc, rEnd = (*rs)->getRelocData()->end(); |
| for (reloc = (*rs)->getRelocData()->begin(); reloc != rEnd; ++reloc) { |
| Relocation* relocation = llvm::cast<Relocation>(reloc); |
| |
| // bypass the reloc if the symbol is in the discarded input section |
| ResolveInfo* info = relocation->symInfo(); |
| if (!info->outSymbol()->hasFragRef() && |
| ResolveInfo::Section == info->type() && |
| ResolveInfo::Undefined == info->desc()) |
| continue; |
| |
| relocation->apply(*m_LDBackend.getRelocator()); |
| } // for all relocations |
| } // for all relocation section |
| m_LDBackend.getRelocator()->finalizeApply(**input); |
| } // for all inputs |
| |
| // apply relocations created by relaxation |
| BranchIslandFactory* br_factory = m_LDBackend.getBRIslandFactory(); |
| BranchIslandFactory::iterator facIter, facEnd = br_factory->end(); |
| for (facIter = br_factory->begin(); facIter != facEnd; ++facIter) { |
| BranchIsland& island = *facIter; |
| BranchIsland::reloc_iterator iter, iterEnd = island.reloc_end(); |
| for (iter = island.reloc_begin(); iter != iterEnd; ++iter) |
| (*iter)->apply(*m_LDBackend.getRelocator()); |
| } |
| |
| // apply the relocations against the .debug_str |
| if (m_pModule->getDebugString().isSuccess()) |
| m_pModule->getDebugString().applyOffset(m_LDBackend); |
| return true; |
| } |
| |
| /// emitOutput - emit the output file. |
| bool ObjectLinker::emitOutput(FileOutputBuffer& pOutput) { |
| return std::error_code() == getWriter()->writeObject(*m_pModule, pOutput); |
| } |
| |
| /// postProcessing - do modification after all processes |
| bool ObjectLinker::postProcessing(FileOutputBuffer& pOutput) { |
| if (LinkerConfig::Object != m_Config.codeGenType()) |
| normalSyncRelocationResult(pOutput); |
| else |
| partialSyncRelocationResult(pOutput); |
| |
| // emit .eh_frame_hdr |
| // eh_frame_hdr should be emitted after syncRelocation, because eh_frame_hdr |
| // needs FDE PC value, which will be corrected at syncRelocation |
| m_LDBackend.postProcessing(pOutput); |
| return true; |
| } |
| |
| void ObjectLinker::normalSyncRelocationResult(FileOutputBuffer& pOutput) { |
| uint8_t* data = pOutput.getBufferStart(); |
| |
| // sync all relocations of all inputs |
| Module::obj_iterator input, inEnd = m_pModule->obj_end(); |
| for (input = m_pModule->obj_begin(); input != inEnd; ++input) { |
| LDContext::sect_iterator rs, rsEnd = (*input)->context()->relocSectEnd(); |
| for (rs = (*input)->context()->relocSectBegin(); rs != rsEnd; ++rs) { |
| // bypass the reloc section if |
| // 1. its section kind is changed to Ignore. (The target section is a |
| // discarded group section.) |
| // 2. it has no reloc data. (All symbols in the input relocs are in the |
| // discarded group sections) |
| if (LDFileFormat::Ignore == (*rs)->kind() || !(*rs)->hasRelocData()) |
| continue; |
| RelocData::iterator reloc, rEnd = (*rs)->getRelocData()->end(); |
| for (reloc = (*rs)->getRelocData()->begin(); reloc != rEnd; ++reloc) { |
| Relocation* relocation = llvm::cast<Relocation>(reloc); |
| |
| // bypass the reloc if the symbol is in the discarded input section |
| ResolveInfo* info = relocation->symInfo(); |
| if (!info->outSymbol()->hasFragRef() && |
| ResolveInfo::Section == info->type() && |
| ResolveInfo::Undefined == info->desc()) |
| continue; |
| |
| // bypass the relocation with NONE type. This is to avoid overwrite the |
| // target result by NONE type relocation if there is a place which has |
| // two relocations to apply to, and one of it is NONE type. The result |
| // we want is the value of the other relocation result. For example, |
| // in .exidx, there are usually an R_ARM_NONE and R_ARM_PREL31 apply to |
| // the same place |
| if (relocation->type() == 0x0) |
| continue; |
| writeRelocationResult(*relocation, data); |
| } // for all relocations |
| } // for all relocation section |
| } // for all inputs |
| |
| // sync relocations created by relaxation |
| BranchIslandFactory* br_factory = m_LDBackend.getBRIslandFactory(); |
| BranchIslandFactory::iterator facIter, facEnd = br_factory->end(); |
| for (facIter = br_factory->begin(); facIter != facEnd; ++facIter) { |
| BranchIsland& island = *facIter; |
| BranchIsland::reloc_iterator iter, iterEnd = island.reloc_end(); |
| for (iter = island.reloc_begin(); iter != iterEnd; ++iter) { |
| Relocation* reloc = *iter; |
| writeRelocationResult(*reloc, data); |
| } |
| } |
| } |
| |
| void ObjectLinker::partialSyncRelocationResult(FileOutputBuffer& pOutput) { |
| uint8_t* data = pOutput.getBufferStart(); |
| |
| // traverse outputs' LDSection to get RelocData |
| Module::iterator sectIter, sectEnd = m_pModule->end(); |
| for (sectIter = m_pModule->begin(); sectIter != sectEnd; ++sectIter) { |
| if (LDFileFormat::Relocation != (*sectIter)->kind()) |
| continue; |
| |
| RelocData* reloc_data = (*sectIter)->getRelocData(); |
| RelocData::iterator relocIter, relocEnd = reloc_data->end(); |
| for (relocIter = reloc_data->begin(); relocIter != relocEnd; ++relocIter) { |
| Relocation* reloc = llvm::cast<Relocation>(relocIter); |
| |
| // bypass the relocation with NONE type. This is to avoid overwrite the |
| // target result by NONE type relocation if there is a place which has |
| // two relocations to apply to, and one of it is NONE type. The result |
| // we want is the value of the other relocation result. For example, |
| // in .exidx, there are usually an R_ARM_NONE and R_ARM_PREL31 apply to |
| // the same place |
| if (reloc->type() == 0x0) |
| continue; |
| writeRelocationResult(*reloc, data); |
| } |
| } |
| } |
| |
| void ObjectLinker::writeRelocationResult(Relocation& pReloc, uint8_t* pOutput) { |
| // get output file offset |
| size_t out_offset = |
| pReloc.targetRef().frag()->getParent()->getSection().offset() + |
| pReloc.targetRef().getOutputOffset(); |
| |
| uint8_t* target_addr = pOutput + out_offset; |
| // byte swapping if target and host has different endian, and then write back |
| if (llvm::sys::IsLittleEndianHost != m_Config.targets().isLittleEndian()) { |
| uint64_t tmp_data = 0; |
| |
| switch (pReloc.size(*m_LDBackend.getRelocator())) { |
| case 8u: |
| std::memcpy(target_addr, &pReloc.target(), 1); |
| break; |
| |
| case 16u: |
| tmp_data = mcld::bswap16(pReloc.target()); |
| std::memcpy(target_addr, &tmp_data, 2); |
| break; |
| |
| case 32u: |
| tmp_data = mcld::bswap32(pReloc.target()); |
| std::memcpy(target_addr, &tmp_data, 4); |
| break; |
| |
| case 64u: |
| tmp_data = mcld::bswap64(pReloc.target()); |
| std::memcpy(target_addr, &tmp_data, 8); |
| break; |
| |
| default: |
| break; |
| } |
| } else { |
| std::memcpy(target_addr, |
| &pReloc.target(), |
| pReloc.size(*m_LDBackend.getRelocator()) / 8); |
| } |
| } |
| |
| } // namespace mcld |
