104 lines · cpp
1//===- DWARF.cpp ----------------------------------------------------------===//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#include "lld/Common/DWARF.h"10#include "lld/Common/ErrorHandler.h"11 12using namespace llvm;13 14namespace lld {15 16DWARFCache::DWARFCache(std::unique_ptr<llvm::DWARFContext> d)17 : dwarf(std::move(d)) {18 for (std::unique_ptr<DWARFUnit> &cu : dwarf->compile_units()) {19 auto report = [](Error err) {20 handleAllErrors(std::move(err),21 [](ErrorInfoBase &info) { warn(info.message()); });22 };23 Expected<const DWARFDebugLine::LineTable *> expectedLT =24 dwarf->getLineTableForUnit(cu.get(), report);25 const DWARFDebugLine::LineTable *lt = nullptr;26 if (expectedLT)27 lt = *expectedLT;28 else29 report(expectedLT.takeError());30 if (!lt)31 continue;32 lineTables.push_back(lt);33 34 // Loop over variable records and insert them to variableLoc.35 for (const auto &entry : cu->dies()) {36 DWARFDie die(cu.get(), &entry);37 // Skip all tags that are not variables.38 if (die.getTag() != dwarf::DW_TAG_variable)39 continue;40 41 // Skip if a local variable because we don't need them for generating42 // error messages. In general, only non-local symbols can fail to be43 // linked.44 if (!dwarf::toUnsigned(die.find(dwarf::DW_AT_external), 0))45 continue;46 47 // Get the source filename index for the variable.48 unsigned file = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_file), 0);49 if (!lt->hasFileAtIndex(file))50 continue;51 52 // Get the line number on which the variable is declared.53 unsigned line = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_line), 0);54 55 // Here we want to take the variable name to add it into variableLoc.56 // Variable can have regular and linkage name associated. At first, we try57 // to get linkage name as it can be different, for example when we have58 // two variables in different namespaces of the same object. Use common59 // name otherwise, but handle the case when it also absent in case if the60 // input object file lacks some debug info.61 StringRef name =62 dwarf::toString(die.find(dwarf::DW_AT_linkage_name),63 dwarf::toString(die.find(dwarf::DW_AT_name), ""));64 if (!name.empty())65 variableLoc.insert({name, {lt, file, line}});66 }67 }68}69 70// Returns the pair of file name and line number describing location of data71// object (variable, array, etc) definition.72std::optional<std::pair<std::string, unsigned>>73DWARFCache::getVariableLoc(StringRef name) {74 // Return if we have no debug information about data object.75 auto it = variableLoc.find(name);76 if (it == variableLoc.end())77 return std::nullopt;78 79 // Take file name string from line table.80 std::string fileName;81 if (!it->second.lt->getFileNameByIndex(82 it->second.file, {},83 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, fileName))84 return std::nullopt;85 86 return std::make_pair(fileName, it->second.line);87}88 89// Returns source line information for a given offset90// using DWARF debug info.91std::optional<DILineInfo> DWARFCache::getDILineInfo(uint64_t offset,92 uint64_t sectionIndex) {93 DILineInfo info;94 for (const llvm::DWARFDebugLine::LineTable *lt : lineTables) {95 if (lt->getFileLineInfoForAddress(96 {offset, sectionIndex}, false, nullptr,97 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, info))98 return info;99 }100 return std::nullopt;101}102 103} // namespace lld104