120 lines · cpp
1//===--- DebugInfoSupport.cpp -- Utils for debug info support ---*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// Utilities to preserve and parse debug info from LinkGraphs.10//11//===----------------------------------------------------------------------===//12 13#include "llvm/ExecutionEngine/Orc/Debugging/DebugInfoSupport.h"14 15#include "llvm/Support/SmallVectorMemoryBuffer.h"16 17#define DEBUG_TYPE "orc"18 19using namespace llvm;20using namespace llvm::orc;21using namespace llvm::jitlink;22 23namespace {24static DenseSet<StringRef> DWARFSectionNames = {25#define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME, OPTION) \26 StringRef(ELF_NAME),27#include "llvm/BinaryFormat/Dwarf.def"28#undef HANDLE_DWARF_SECTION29};30 31// We might be able to drop relocations to symbols that do end up32// being pruned by the linker, but for now we just preserve all33static void preserveDWARFSection(LinkGraph &G, Section &Sec) {34 DenseMap<Block *, Symbol *> Preserved;35 for (auto Sym : Sec.symbols()) {36 auto [It, Inserted] = Preserved.try_emplace(&Sym->getBlock());37 if (Inserted || Sym->isLive())38 It->second = Sym;39 }40 for (auto Block : Sec.blocks()) {41 auto &PSym = Preserved[Block];42 if (!PSym)43 PSym = &G.addAnonymousSymbol(*Block, 0, 0, false, true);44 else if (!PSym->isLive())45 PSym->setLive(true);46 }47}48 49static SmallVector<char, 0> getSectionData(Section &Sec) {50 SmallVector<char, 0> SecData;51 SmallVector<Block *, 8> SecBlocks(Sec.blocks().begin(), Sec.blocks().end());52 std::sort(SecBlocks.begin(), SecBlocks.end(), [](Block *LHS, Block *RHS) {53 return LHS->getAddress() < RHS->getAddress();54 });55 // Convert back to what object file would have, one blob of section content56 // Assumes all zerofill57 // TODO handle alignment?58 // TODO handle alignment offset?59 for (auto *Block : SecBlocks) {60 if (Block->isZeroFill())61 SecData.resize(SecData.size() + Block->getSize(), 0);62 else63 SecData.append(Block->getContent().begin(), Block->getContent().end());64 }65 return SecData;66}67 68static void dumpDWARFContext(DWARFContext &DC) {69 auto options = llvm::DIDumpOptions();70 options.DumpType &= ~DIDT_UUID;71 options.DumpType &= ~(1 << DIDT_ID_DebugFrame);72 LLVM_DEBUG(DC.dump(dbgs(), options));73}74 75} // namespace76 77Error llvm::orc::preserveDebugSections(LinkGraph &G) {78 if (!G.getTargetTriple().isOSBinFormatELF()) {79 return make_error<StringError>(80 "preserveDebugSections only supports ELF LinkGraphs!",81 inconvertibleErrorCode());82 }83 for (auto &Sec : G.sections()) {84 if (DWARFSectionNames.count(Sec.getName())) {85 LLVM_DEBUG(dbgs() << "Preserving DWARF section " << Sec.getName()86 << "\n");87 preserveDWARFSection(G, Sec);88 }89 }90 return Error::success();91}92 93Expected<std::pair<std::unique_ptr<DWARFContext>,94 StringMap<std::unique_ptr<MemoryBuffer>>>>95llvm::orc::createDWARFContext(LinkGraph &G) {96 if (!G.getTargetTriple().isOSBinFormatELF()) {97 return make_error<StringError>(98 "createDWARFContext only supports ELF LinkGraphs!",99 inconvertibleErrorCode());100 }101 StringMap<std::unique_ptr<MemoryBuffer>> DWARFSectionData;102 for (auto &Sec : G.sections()) {103 if (DWARFSectionNames.count(Sec.getName())) {104 auto SecData = getSectionData(Sec);105 auto Name = Sec.getName();106 // DWARFContext expects the section name to not start with a dot107 Name.consume_front(".");108 LLVM_DEBUG(dbgs() << "Creating DWARFContext section " << Name109 << " with size " << SecData.size() << "\n");110 DWARFSectionData[Name] =111 std::make_unique<SmallVectorMemoryBuffer>(std::move(SecData));112 }113 }114 auto Ctx =115 DWARFContext::create(DWARFSectionData, G.getPointerSize(),116 G.getEndianness() == llvm::endianness::little);117 dumpDWARFContext(*Ctx);118 return std::make_pair(std::move(Ctx), std::move(DWARFSectionData));119}120