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//===- GdbIndex.cpp -------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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
// https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html.
//
//===----------------------------------------------------------------------===//
#include "GdbIndex.h"
#include "Symbols.h"
#include "lld/Common/Memory.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugPubTable.h"
#include "llvm/Object/ELFObjectFile.h"
using namespace llvm;
using namespace llvm::object;
using namespace lld;
using namespace lld::elf;
template <class ELFT> LLDDwarfObj<ELFT>::LLDDwarfObj(ObjFile<ELFT> *Obj) {
for (InputSectionBase *Sec : Obj->getSections()) {
if (!Sec)
continue;
if (LLDDWARFSection *M = StringSwitch<LLDDWARFSection *>(Sec->Name)
.Case(".debug_info", &InfoSection)
.Case(".debug_ranges", &RangeSection)
.Case(".debug_line", &LineSection)
.Default(nullptr)) {
Sec->maybeUncompress();
M->Data = toStringRef(Sec->Data);
M->Sec = Sec;
continue;
}
if (Sec->Name == ".debug_abbrev")
AbbrevSection = toStringRef(Sec->Data);
else if (Sec->Name == ".debug_gnu_pubnames")
GnuPubNamesSection = toStringRef(Sec->Data);
else if (Sec->Name == ".debug_gnu_pubtypes")
GnuPubTypesSection = toStringRef(Sec->Data);
else if (Sec->Name == ".debug_str")
StrSection = toStringRef(Sec->Data);
}
}
// 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>
Optional<RelocAddrEntry>
LLDDwarfObj<ELFT>::findAux(const InputSectionBase &Sec, uint64_t Pos,
ArrayRef<RelTy> Rels) const {
auto It = std::lower_bound(
Rels.begin(), Rels.end(), Pos,
[](const RelTy &A, uint64_t B) { return A.r_offset < B; });
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->getELFSyms()[SymIndex];
uint32_t SecIndex = File->getSectionIndex(Sym);
// Broken debug info can point to a non-Defined symbol.
auto *DR = dyn_cast<Defined>(&File->getRelocTargetSym(Rel));
if (!DR) {
error("unsupported relocation target while parsing debug info");
return None;
}
uint64_t Val = DR->Value + getAddend<ELFT>(Rel);
// 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();
return RelocAddrEntry{SecIndex, Val};
}
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 elf::LLDDwarfObj<ELF32LE>;
template class elf::LLDDwarfObj<ELF32BE>;
template class elf::LLDDwarfObj<ELF64LE>;
template class elf::LLDDwarfObj<ELF64BE>;
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