blob: a00189a0e3a28452171ca4034995c7d5456064b4 [file] [log] [blame]
//===- DWARF.cpp ----------------------------------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// The -gdb-index option instructs the linker to emit a .gdb_index section.
// The section contains information to make gdb startup faster.
// The format of the section is described at
#include "DWARF.h"
#include "Symbols.h"
#include "Target.h"
#include "lld/Common/Memory.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugPubTable.h"
#include "llvm/Object/ELFObjectFile.h"
using namespace llvm;
using namespace llvm::object;
namespace lld {
namespace elf {
template <class ELFT> LLDDwarfObj<ELFT>::LLDDwarfObj(ObjFile<ELFT> *obj) {
for (InputSectionBase *sec : obj->getSections()) {
if (!sec)
if (LLDDWARFSection *m =
StringSwitch<LLDDWARFSection *>(sec->name)
.Case(".debug_addr", &addrSection)
.Case(".debug_gnu_pubnames", &gnuPubnamesSection)
.Case(".debug_gnu_pubtypes", &gnuPubtypesSection)
.Case(".debug_info", &infoSection)
.Case(".debug_ranges", &rangesSection)
.Case(".debug_rnglists", &rnglistsSection)
.Case(".debug_str_offsets", &strOffsetsSection)
.Case(".debug_line", &lineSection)
.Default(nullptr)) {
m->Data = toStringRef(sec->data());
m->sec = sec;
if (sec->name == ".debug_abbrev")
abbrevSection = toStringRef(sec->data());
else if (sec->name == ".debug_str")
strSection = toStringRef(sec->data());
else if (sec->name == ".debug_line_str")
lineStrSection = toStringRef(sec->data());
namespace {
template <class RelTy> struct LLDRelocationResolver {
// In the ELF ABIs, S sepresents the value of the symbol in the relocation
// entry. For Rela, the addend is stored as part of the relocation entry.
static uint64_t resolve(object::RelocationRef ref, uint64_t s,
uint64_t /* A */) {
return s + ref.getRawDataRefImpl().p;
template <class ELFT> struct LLDRelocationResolver<Elf_Rel_Impl<ELFT, false>> {
// For Rel, the addend A is supplied by the caller.
static uint64_t resolve(object::RelocationRef /*Ref*/, uint64_t s,
uint64_t a) {
return s + a;
} // namespace
// Find if there is a relocation at Pos in Sec. The code is a bit
// more complicated than usual because we need to pass a section index
// to llvm since it has no idea about InputSection.
template <class ELFT>
template <class RelTy>
LLDDwarfObj<ELFT>::findAux(const InputSectionBase &sec, uint64_t pos,
ArrayRef<RelTy> rels) const {
auto it =
partition_point(rels, [=](const RelTy &a) { return a.r_offset < pos; });
if (it == rels.end() || it->r_offset != pos)
return None;
const RelTy &rel = *it;
const ObjFile<ELFT> *file = sec.getFile<ELFT>();
uint32_t symIndex = rel.getSymbol(config->isMips64EL);
const typename ELFT::Sym &sym = file->template getELFSyms<ELFT>()[symIndex];
uint32_t secIndex = file->getSectionIndex(sym);
// An undefined symbol may be a symbol defined in a discarded section. We
// shall still resolve it. This is important for --gdb-index: the end address
// offset of an entry in .debug_ranges is relocated. If it is not resolved,
// its zero value will terminate the decoding of .debug_ranges prematurely.
Symbol &s = file->getRelocTargetSym(rel);
uint64_t val = 0;
if (auto *dr = dyn_cast<Defined>(&s)) {
val = dr->value;
// FIXME: We should be consistent about always adding the file
// offset or not.
if (dr->section->flags & ELF::SHF_ALLOC)
val += cast<InputSection>(dr->section)->getOffsetInFile();
DataRefImpl d;
d.p = getAddend<ELFT>(rel);
return RelocAddrEntry{secIndex, RelocationRef(d, nullptr),
val, Optional<object::RelocationRef>(),
0, LLDRelocationResolver<RelTy>::resolve};
template <class ELFT>
Optional<RelocAddrEntry> LLDDwarfObj<ELFT>::find(const llvm::DWARFSection &s,
uint64_t pos) const {
auto &sec = static_cast<const LLDDWARFSection &>(s);
if (sec.sec->areRelocsRela)
return findAux(*sec.sec, pos, sec.sec->template relas<ELFT>());
return findAux(*sec.sec, pos, sec.sec->template rels<ELFT>());
template class LLDDwarfObj<ELF32LE>;
template class LLDDwarfObj<ELF32BE>;
template class LLDDwarfObj<ELF64LE>;
template class LLDDwarfObj<ELF64BE>;
} // namespace elf
} // namespace lld