void GarbageCollection::stripSections() { // Traverse all the input Regular and BSS sections, if a section is not found // in the ReferencedSections, then it should be garbage collected Module::obj_iterator obj, objEnd = m_Module.obj_end(); for (obj = m_Module.obj_begin(); obj != objEnd; ++obj) { LDContext::sect_iterator sect, sectEnd = (*obj)->context()->sectEnd(); for (sect = (*obj)->context()->sectBegin(); sect != sectEnd; ++sect) { LDSection* section = *sect; if (LDFileFormat::Regular != section->kind() && LDFileFormat::BSS != section->kind()) continue; if (m_ReferencedSections.find(section) == m_ReferencedSections.end()) section->setKind(LDFileFormat::Ignore); } } // Traverse all the relocation sections, if its target section is set to // Ignore, then set the relocation section to Ignore as well Module::obj_iterator input, inEnd = m_Module.obj_end(); for (input = m_Module.obj_begin(); input != inEnd; ++input) { LDContext::sect_iterator rs, rsEnd = (*input)->context()->relocSectEnd(); for (rs = (*input)->context()->relocSectBegin(); rs != rsEnd; ++rs) { LDSection* reloc_sect = *rs; if (LDFileFormat::Ignore == reloc_sect->getLink()->kind()) reloc_sect->setKind(LDFileFormat::Ignore); } } }
void GarbageCollection::getEntrySections(SectionVecTy& pEntry) { // all the KEEP sections defined in ldscript are entries, traverse all the // input sections and check the SectionMap to find the KEEP sections Module::obj_iterator obj, objEnd = m_Module.obj_end(); SectionMap& sect_map = m_Module.getScript().sectionMap(); for (obj = m_Module.obj_begin(); obj != objEnd; ++obj) { const std::string input_name = (*obj)->name(); LDContext::sect_iterator sect, sectEnd = (*obj)->context()->sectEnd(); for (sect = (*obj)->context()->sectBegin(); sect != sectEnd; ++sect) { LDSection* section = *sect; if (LDFileFormat::Regular != section->kind() && LDFileFormat::BSS != section->kind()) continue; SectionMap::Input* sm_input = sect_map.find(input_name, section->name()).second; if ((sm_input != NULL) && (InputSectDesc::Keep == sm_input->policy())) pEntry.push_back(section); } } // get the sections those the entry symbols defined in Module::SymbolTable& sym_tab = m_Module.getSymbolTable(); if (LinkerConfig::Exec == m_Config.codeGenType()) { assert(NULL != m_pEntry); pEntry.push_back(&m_pEntry->fragRef()->frag()->getParent()->getSection()); } else { // when building shared objects, the global define symbols are entries SymbolCategory::iterator it, end = sym_tab.regularEnd(); for (it = sym_tab.dynamicBegin(); it != end; ++it) { LDSymbol* sym = *it; if (!sym->resolveInfo()->isDefine() || !sym->hasFragRef()) continue; // only the target symbols defined in the concerned sections can make // the reference const LDSection* sect = &sym->fragRef()->frag()->getParent()->getSection(); if (sect->kind() != LDFileFormat::Regular && sect->kind() != LDFileFormat::BSS) continue; pEntry.push_back(sect); } } }
bool SectionSymbolSet::finalize(LDSection& pOutSect, SymbolTable& pSymTab, bool relocatable) { if (!relocatable && pOutSect.size() == 0) return true; LDSymbol* sym = get(pOutSect); assert(NULL != sym); SectionData* data = NULL; switch (pOutSect.kind()) { case LDFileFormat::Relocation: // Relocation section should not have section symbol. return true; case LDFileFormat::EhFrame: if (EhFrame *ehframe = pOutSect.getEhFrame()) data = ehframe->getSectionData(); break; default: data = pOutSect.getSectionData(); break; } FragmentRef* frag_ref; if (data && !data->empty()) frag_ref = FragmentRef::Create(data->front(), 0x0); else frag_ref = FragmentRef::Null(); sym->setFragmentRef(frag_ref); // push symbol into output symbol table pSymTab.add(*sym); return true; }
void IdenticalCodeFolding::findCandidates(FoldingCandidates& pCandidateList) { Module::obj_iterator obj, objEnd = m_Module.obj_end(); for (obj = m_Module.obj_begin(); obj != objEnd; ++obj) { std::set<const LDSection*> funcptr_access_set; typedef std::map<LDSection*, LDSection*> CandidateMap; CandidateMap candidate_map; LDContext::sect_iterator sect, sectEnd = (*obj)->context()->sectEnd(); for (sect = (*obj)->context()->sectBegin(); sect != sectEnd; ++sect) { switch ((*sect)->kind()) { case LDFileFormat::TEXT: { candidate_map.insert( std::make_pair(*sect, reinterpret_cast<LDSection*>(NULL))); break; } case LDFileFormat::Relocation: { LDSection* target = (*sect)->getLink(); if (target->kind() == LDFileFormat::TEXT) { candidate_map[target] = *sect; } // Safe icf if (m_Config.options().getICFMode() == GeneralOptions::ICF::Safe) { RelocData::iterator rel, relEnd = (*sect)->getRelocData()->end(); for (rel = (*sect)->getRelocData()->begin(); rel != relEnd; ++rel) { LDSymbol* sym = rel->symInfo()->outSymbol(); if (sym->hasFragRef() && (sym->type() == ResolveInfo::Function)) { const LDSection* def = &sym->fragRef()->frag()->getParent()->getSection(); if (!isSymCtorOrDtor(*rel->symInfo()) && m_Backend.mayHaveUnsafeFunctionPointerAccess(*target) && m_Backend.getRelocator() ->mayHaveFunctionPointerAccess(*rel)) { funcptr_access_set.insert(def); } } } // for each reloc } break; } default: { // skip break; } } // end of switch } // for each section CandidateMap::iterator candidate, candidateEnd = candidate_map.end(); for (candidate = candidate_map.begin(); candidate != candidateEnd; ++candidate) { if ((m_Config.options().getICFMode() == GeneralOptions::ICF::All) || (funcptr_access_set.count(candidate->first) == 0)) { size_t index = m_KeptSections.size(); m_KeptSections[candidate->first] = ObjectAndId(*obj, index); pCandidateList.push_back( FoldingCandidate(candidate->first, candidate->second, *obj)); } } // for each possible candidate } // for each obj }
bool ARMGNULDBackend::readSection(Input& pInput, MCLinker& pLinker, LDSection& pInputSectHdr) { LDSection& out_sect = pLinker.getOrCreateOutputSectHdr(pInputSectHdr.name(), pInputSectHdr.kind(), pInputSectHdr.type(), pInputSectHdr.flag()); // FIXME: (Luba) // Handle ARM attributes in the right way. // In current milestone, MCLinker goes through the shortcut. // It reads input's ARM attributes and copies the first ARM attributes // into the output file. The correct way is merge these sections, not // just copy. if ((0 == out_sect.name().compare(".ARM.attributes")) && (0 != out_sect.size())) return true; MemoryRegion* region = pInput.memArea()->request(pInputSectHdr.offset(), pInputSectHdr.size()); llvm::MCSectionData& sect_data = pLinker.getOrCreateSectData(pInputSectHdr); new MCRegionFragment(*region, §_data); out_sect.setSize(out_sect.size() + pInputSectHdr.size()); return true; }
/// merge Input Sections bool HexagonLDBackend::mergeSection(Module& pModule, const Input& pInputFile, LDSection& pInputSection) { if ((pInputSection.flag() & llvm::ELF::SHF_HEX_GPREL) || (pInputSection.kind() == LDFileFormat::LinkOnce) || (pInputSection.kind() == LDFileFormat::Target)) { SectionData* sd = NULL; if (!m_psdata->hasSectionData()) { sd = IRBuilder::CreateSectionData(*m_psdata); m_psdata->setSectionData(sd); } sd = m_psdata->getSectionData(); MoveSectionDataAndSort(*pInputSection.getSectionData(), *sd); } else { ObjectBuilder builder(pModule); builder.MergeSection(pInputFile, pInputSection); } return true; }
/// emitSectionData void ELFObjectWriter::emitSectionData(const LDSection& pSection, MemoryRegion& pRegion) const { const SectionData* sd = NULL; switch (pSection.kind()) { case LDFileFormat::Relocation: assert(pSection.hasRelocData()); return; case LDFileFormat::EhFrame: assert(pSection.hasEhFrame()); sd = pSection.getEhFrame()->getSectionData(); break; default: assert(pSection.hasSectionData()); sd = pSection.getSectionData(); break; } emitSectionData(*sd, pRegion); }
void IdenticalCodeFolding::foldIdenticalCode() { // 1. Find folding candidates. FoldingCandidates candidate_list; findCandidates(candidate_list); // 2. Initialize constant section content for (size_t i = 0; i < candidate_list.size(); ++i) { candidate_list[i].initConstantContent(m_Backend, m_KeptSections); } // 3. Find identical code until convergence bool converged = false; size_t iterations = 0; while (!converged && (iterations < m_Config.options().getICFIterations())) { converged = matchCandidates(candidate_list); ++iterations; } if (m_Config.options().printICFSections()) { debug(diag::debug_icf_iterations) << iterations; } // 4. Fold the identical code typedef std::set<Input*> FoldedObjects; FoldedObjects folded_objs; KeptSections::iterator kept, keptEnd = m_KeptSections.end(); size_t index = 0; for (kept = m_KeptSections.begin(); kept != keptEnd; ++kept, ++index) { LDSection* sect = (*kept).first; Input* obj = (*kept).second.first; size_t kept_index = (*kept).second.second; if (index != kept_index) { sect->setKind(LDFileFormat::Folded); folded_objs.insert(obj); if (m_Config.options().printICFSections()) { KeptSections::iterator it = m_KeptSections.begin() + kept_index; LDSection* kept_sect = (*it).first; Input* kept_obj = (*it).second.first; debug(diag::debug_icf_folded_section) << sect->name() << obj->name() << kept_sect->name() << kept_obj->name(); } } } // Adjust the fragment reference of the folded symbols. FoldedObjects::iterator fobj, fobjEnd = folded_objs.end(); for (fobj = folded_objs.begin(); fobj != fobjEnd; ++fobj) { LDContext::sym_iterator sym, symEnd = (*fobj)->context()->symTabEnd(); for (sym = (*fobj)->context()->symTabBegin(); sym != symEnd; ++sym) { if ((*sym)->hasFragRef() && ((*sym)->type() == ResolveInfo::Function)) { LDSymbol* out_sym = (*sym)->resolveInfo()->outSymbol(); FragmentRef* frag_ref = out_sym->fragRef(); LDSection* sect = &(frag_ref->frag()->getParent()->getSection()); if (sect->kind() == LDFileFormat::Folded) { size_t kept_index = m_KeptSections[sect].second; LDSection* kept_sect = (*(m_KeptSections.begin() + kept_index)).first; frag_ref->assign(kept_sect->getSectionData()->front(), frag_ref->offset()); } } } // for each symbol } // for each folded object }
bool MipsGNULDBackend::doRelax(Module& pModule, IRBuilder& pBuilder, bool& pFinished) { assert(getStubFactory() != NULL && getBRIslandFactory() != NULL); bool isRelaxed = false; for (Module::obj_iterator input = pModule.obj_begin(); input != pModule.obj_end(); ++input) { LDContext* context = (*input)->context(); for (LDContext::sect_iterator rs = context->relocSectBegin(); rs != context->relocSectEnd(); ++rs) { LDSection* sec = *rs; if (LDFileFormat::Ignore == sec->kind() || !sec->hasRelocData()) continue; for (RelocData::iterator reloc = sec->getRelocData()->begin(); reloc != sec->getRelocData()->end(); ++reloc) { if (llvm::ELF::R_MIPS_26 != reloc->type()) continue; if (relaxRelocation(pBuilder, *llvm::cast<Relocation>(reloc))) isRelaxed = true; } } } SectionData* textData = getOutputFormat()->getText().getSectionData(); // find the first fragment w/ invalid offset due to stub insertion Fragment* invalid = NULL; pFinished = true; for (BranchIslandFactory::iterator ii = getBRIslandFactory()->begin(), ie = getBRIslandFactory()->end(); ii != ie; ++ii) { BranchIsland& island = *ii; if (island.end() == textData->end()) break; Fragment* exit = island.end(); if ((island.offset() + island.size()) > exit->getOffset()) { invalid = exit; pFinished = false; break; } } // reset the offset of invalid fragments while (invalid != NULL) { invalid->setOffset(invalid->getPrevNode()->getOffset() + invalid->getPrevNode()->size()); invalid = invalid->getNextNode(); } // reset the size of .text if (isRelaxed) getOutputFormat()->getText().setSize(textData->back().getOffset() + textData->back().size()); return isRelaxed; }