ObjectFileTransformer.cpp
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//===- ObjectFileTransformer.cpp --------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include <unordered_set>
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/MachOUniversal.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/DebugInfo/GSYM/ObjectFileTransformer.h"
#include "llvm/DebugInfo/GSYM/GsymCreator.h"
using namespace llvm;
using namespace gsym;
constexpr uint32_t NT_GNU_BUILD_ID_TAG = 0x03;
static std::vector<uint8_t> getUUID(const object::ObjectFile &Obj) {
// Extract the UUID from the object file
std::vector<uint8_t> UUID;
if (auto *MachO = dyn_cast<object::MachOObjectFile>(&Obj)) {
const ArrayRef<uint8_t> MachUUID = MachO->getUuid();
if (!MachUUID.empty())
UUID.assign(MachUUID.data(), MachUUID.data() + MachUUID.size());
} else if (isa<object::ELFObjectFileBase>(&Obj)) {
const StringRef GNUBuildID(".note.gnu.build-id");
for (const object::SectionRef &Sect : Obj.sections()) {
Expected<StringRef> SectNameOrErr = Sect.getName();
if (!SectNameOrErr) {
consumeError(SectNameOrErr.takeError());
continue;
}
StringRef SectName(*SectNameOrErr);
if (SectName != GNUBuildID)
continue;
StringRef BuildIDData;
Expected<StringRef> E = Sect.getContents();
if (E)
BuildIDData = *E;
else {
consumeError(E.takeError());
continue;
}
DataExtractor Decoder(BuildIDData, Obj.makeTriple().isLittleEndian(), 8);
uint64_t Offset = 0;
const uint32_t NameSize = Decoder.getU32(&Offset);
const uint32_t PayloadSize = Decoder.getU32(&Offset);
const uint32_t PayloadType = Decoder.getU32(&Offset);
StringRef Name(Decoder.getFixedLengthString(&Offset, NameSize));
if (Name == "GNU" && PayloadType == NT_GNU_BUILD_ID_TAG) {
Offset = alignTo(Offset, 4);
StringRef UUIDBytes(Decoder.getBytes(&Offset, PayloadSize));
if (!UUIDBytes.empty()) {
auto Ptr = reinterpret_cast<const uint8_t *>(UUIDBytes.data());
UUID.assign(Ptr, Ptr + UUIDBytes.size());
}
}
}
}
return UUID;
}
llvm::Error ObjectFileTransformer::convert(const object::ObjectFile &Obj,
raw_ostream &Log,
GsymCreator &Gsym) {
using namespace llvm::object;
const bool IsMachO = isa<MachOObjectFile>(&Obj);
const bool IsELF = isa<ELFObjectFileBase>(&Obj);
// Read build ID.
Gsym.setUUID(getUUID(Obj));
// Parse the symbol table.
size_t NumBefore = Gsym.getNumFunctionInfos();
for (const object::SymbolRef &Sym : Obj.symbols()) {
Expected<SymbolRef::Type> SymType = Sym.getType();
if (!SymType) {
consumeError(SymType.takeError());
continue;
}
Expected<uint64_t> AddrOrErr = Sym.getValue();
if (!AddrOrErr)
// TODO: Test this error.
return AddrOrErr.takeError();
if (SymType.get() != SymbolRef::Type::ST_Function ||
!Gsym.IsValidTextAddress(*AddrOrErr) ||
Gsym.hasFunctionInfoForAddress(*AddrOrErr))
continue;
// Function size for MachO files will be 0
constexpr bool NoCopy = false;
const uint64_t size = IsELF ? ELFSymbolRef(Sym).getSize() : 0;
Expected<StringRef> Name = Sym.getName();
if (!Name) {
logAllUnhandledErrors(Name.takeError(), Log, "ObjectFileTransformer: ");
continue;
}
// Remove the leading '_' character in any symbol names if there is one
// for mach-o files.
if (IsMachO)
Name->consume_front("_");
Gsym.addFunctionInfo(
FunctionInfo(*AddrOrErr, size, Gsym.insertString(*Name, NoCopy)));
}
size_t FunctionsAddedCount = Gsym.getNumFunctionInfos() - NumBefore;
Log << "Loaded " << FunctionsAddedCount << " functions from symbol table.\n";
return Error::success();
}