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llvm-project/bolt/lib/Rewrite/DWARFRewriter.cpp

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//===- bolt/Rewrite/DWARFRewriter.cpp -------------------------------------===//
//
// 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 "bolt/Rewrite/DWARFRewriter.h"
#include "bolt/Core/BinaryContext.h"
#include "bolt/Core/BinaryFunction.h"
#include "bolt/Core/DebugData.h"
#include "bolt/Core/ParallelUtilities.h"
#include "bolt/Rewrite/RewriteInstance.h"
#include "bolt/Utils/Utils.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/DWP/DWP.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/ThreadPool.h"
#include "llvm/Support/ToolOutputFile.h"
#include <algorithm>
#include <cstdint>
#include <string>
#include <unordered_map>
#undef DEBUG_TYPE
#define DEBUG_TYPE "bolt"
LLVM_ATTRIBUTE_UNUSED
static void printDie(const DWARFDie &DIE) {
DIDumpOptions DumpOpts;
DumpOpts.ShowForm = true;
DumpOpts.Verbose = true;
DumpOpts.ChildRecurseDepth = 0;
DumpOpts.ShowChildren = 0;
DIE.dump(dbgs(), 0, DumpOpts);
}
struct AttrInfo {
DWARFFormValue V;
uint64_t Offset;
uint32_t Size; // Size of the attribute.
};
/// Finds attributes FormValue and Offset.
///
/// \param DIE die to look up in.
/// \param Index the attribute index to extract.
/// \return an optional AttrInfo with DWARFFormValue and Offset.
static Optional<AttrInfo>
findAttributeInfo(const DWARFDie DIE,
const DWARFAbbreviationDeclaration *AbbrevDecl,
uint32_t Index) {
const DWARFUnit &U = *DIE.getDwarfUnit();
uint64_t Offset =
AbbrevDecl->getAttributeOffsetFromIndex(Index, DIE.getOffset(), U);
Optional<DWARFFormValue> Value =
AbbrevDecl->getAttributeValueFromOffset(Index, Offset, U);
if (!Value)
return None;
// AttributeSpec
const DWARFAbbreviationDeclaration::AttributeSpec *AttrVal =
AbbrevDecl->attributes().begin() + Index;
uint32_t ValSize = 0;
Optional<int64_t> ValSizeOpt = AttrVal->getByteSize(U);
if (ValSizeOpt) {
ValSize = static_cast<uint32_t>(*ValSizeOpt);
} else {
DWARFDataExtractor DebugInfoData = U.getDebugInfoExtractor();
uint64_t NewOffset = Offset;
DWARFFormValue::skipValue(Value->getForm(), DebugInfoData, &NewOffset,
U.getFormParams());
// This includes entire size of the entry, which might not be just the
// encoding part. For example for DW_AT_loc it will include expression
// location.
ValSize = NewOffset - Offset;
}
return AttrInfo{*Value, Offset, ValSize};
}
/// Finds attributes FormValue and Offset.
///
/// \param DIE die to look up in.
/// \param Attr the attribute to extract.
/// \return an optional AttrInfo with DWARFFormValue and Offset.
static Optional<AttrInfo> findAttributeInfo(const DWARFDie DIE,
dwarf::Attribute Attr) {
if (!DIE.isValid())
return None;
const DWARFAbbreviationDeclaration *AbbrevDecl =
DIE.getAbbreviationDeclarationPtr();
if (!AbbrevDecl)
return None;
Optional<uint32_t> Index = AbbrevDecl->findAttributeIndex(Attr);
if (!Index)
return None;
return findAttributeInfo(DIE, AbbrevDecl, *Index);
}
using namespace llvm;
using namespace llvm::support::endian;
using namespace object;
using namespace bolt;
namespace opts {
extern cl::OptionCategory BoltCategory;
extern cl::opt<unsigned> Verbosity;
extern cl::opt<std::string> OutputFilename;
static cl::opt<bool>
KeepARanges("keep-aranges",
cl::desc("keep or generate .debug_aranges section if .gdb_index is written"),
cl::ZeroOrMore,
cl::Hidden,
cl::cat(BoltCategory));
static cl::opt<bool>
DeterministicDebugInfo("deterministic-debuginfo",
cl::desc("disables parallel execution of tasks that may produce"
"nondeterministic debug info"),
cl::init(true),
cl::cat(BoltCategory));
static cl::opt<std::string> DwarfOutputPath(
"dwarf-output-path",
cl::desc("Path to where .dwo files or dwp file will be written out to."),
cl::init(""), cl::cat(BoltCategory));
static cl::opt<bool>
WriteDWP("write-dwp",
cl::desc("output a single dwarf package file (dwp) instead of "
"multiple non-relocatable dwarf object files (dwo)."),
cl::init(false), cl::cat(BoltCategory));
static cl::opt<bool>
DebugSkeletonCu("debug-skeleton-cu",
cl::desc("prints out offsetrs for abbrev and debu_info of "
"Skeleton CUs that get patched."),
cl::ZeroOrMore, cl::Hidden, cl::init(false),
cl::cat(BoltCategory));
} // namespace opts
/// Returns DWO Name to be used. Handles case where user specifies output DWO
/// directory, and there are duplicate names. Assumes DWO ID is unique.
static std::string
getDWOName(llvm::DWARFUnit &CU,
std::unordered_map<std::string, uint32_t> *NameToIndexMap,
std::unordered_map<uint64_t, std::string> &DWOIdToName) {
llvm::Optional<uint64_t> DWOId = CU.getDWOId();
assert(DWOId && "DWO ID not found.");
(void)DWOId;
auto NameIter = DWOIdToName.find(*DWOId);
if (NameIter != DWOIdToName.end())
return NameIter->second;
std::string DWOName = dwarf::toString(
CU.getUnitDIE().find({dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}),
"");
assert(!DWOName.empty() &&
"DW_AT_dwo_name/DW_AT_GNU_dwo_name does not exists.");
if (NameToIndexMap && !opts::DwarfOutputPath.empty()) {
auto Iter = NameToIndexMap->find(DWOName);
if (Iter == NameToIndexMap->end())
Iter = NameToIndexMap->insert({DWOName, 0}).first;
DWOName.append(std::to_string(Iter->second));
++Iter->second;
}
DWOName.append(".dwo");
DWOIdToName[*DWOId] = DWOName;
return DWOName;
}
static bool isHighPcFormEightBytes(dwarf::Form DwarfForm) {
return DwarfForm == dwarf::DW_FORM_addr || DwarfForm == dwarf::DW_FORM_data8;
}
void DWARFRewriter::updateDebugInfo() {
ErrorOr<BinarySection &> DebugInfo = BC.getUniqueSectionByName(".debug_info");
if (!DebugInfo)
return;
auto *DebugInfoPatcher =
static_cast<DebugInfoBinaryPatcher *>(DebugInfo->getPatcher());
ARangesSectionWriter = std::make_unique<DebugARangesSectionWriter>();
RangesSectionWriter = std::make_unique<DebugRangesSectionWriter>();
StrWriter = std::make_unique<DebugStrWriter>(&BC);
AbbrevWriter = std::make_unique<DebugAbbrevWriter>(*BC.DwCtx);
AddrWriter = std::make_unique<DebugAddrWriter>(&BC);
DebugLoclistWriter::setAddressWriter(AddrWriter.get());
uint64_t NumCUs = BC.DwCtx->getNumCompileUnits();
if ((opts::NoThreads || opts::DeterministicDebugInfo) &&
BC.getNumDWOCUs() == 0) {
// Use single entry for efficiency when running single-threaded
NumCUs = 1;
}
LocListWritersByCU.reserve(NumCUs);
for (size_t CUIndex = 0; CUIndex < NumCUs; ++CUIndex)
LocListWritersByCU[CUIndex] = std::make_unique<DebugLocWriter>(&BC);
// Unordered maps to handle name collision if output DWO directory is
// specified.
std::unordered_map<std::string, uint32_t> NameToIndexMap;
std::unordered_map<uint64_t, std::string> DWOIdToName;
std::mutex AccessMutex;
auto updateDWONameCompDir = [&](DWARFUnit &Unit) -> void {
const DWARFDie &DIE = Unit.getUnitDIE();
Optional<AttrInfo> AttrInfoVal =
findAttributeInfo(DIE, dwarf::DW_AT_GNU_dwo_name);
(void)AttrInfoVal;
assert(AttrInfoVal && "Skeleton CU doesn't have dwo_name.");
std::string ObjectName = "";
{
std::lock_guard<std::mutex> Lock(AccessMutex);
ObjectName = getDWOName(Unit, &NameToIndexMap, DWOIdToName);
}
uint32_t NewOffset = StrWriter->addString(ObjectName.c_str());
DebugInfoPatcher->addLE32Patch(AttrInfoVal->Offset, NewOffset,
AttrInfoVal->Size);
AttrInfoVal = findAttributeInfo(DIE, dwarf::DW_AT_comp_dir);
(void)AttrInfoVal;
assert(AttrInfoVal && "DW_AT_comp_dir is not in Skeleton CU.");
if (!opts::DwarfOutputPath.empty()) {
uint32_t NewOffset = StrWriter->addString(opts::DwarfOutputPath.c_str());
DebugInfoPatcher->addLE32Patch(AttrInfoVal->Offset, NewOffset,
AttrInfoVal->Size);
}
};
auto processUnitDIE = [&](size_t CUIndex, DWARFUnit *Unit) {
// Check if the unit is a skeleton and we need special updates for it and
// its matching split/DWO CU.
Optional<DWARFUnit *> SplitCU;
Optional<uint64_t> RangesBase;
llvm::Optional<uint64_t> DWOId = Unit->getDWOId();
if (DWOId)
SplitCU = BC.getDWOCU(*DWOId);
DebugLocWriter *DebugLocWriter = nullptr;
// Skipping CUs that failed to load.
if (SplitCU) {
updateDWONameCompDir(*Unit);
// Assuming there is unique DWOID per binary. i.e. two or more CUs don't
// have same DWO ID.
assert(LocListWritersByCU.count(*DWOId) == 0 &&
"LocList writer for DWO unit already exists.");
{
std::lock_guard<std::mutex> Lock(AccessMutex);
DebugLocWriter =
LocListWritersByCU
.insert(
{*DWOId, std::make_unique<DebugLoclistWriter>(&BC, *DWOId)})
.first->second.get();
}
DebugInfoBinaryPatcher *DwoDebugInfoPatcher =
llvm::cast<DebugInfoBinaryPatcher>(
getBinaryDWODebugInfoPatcher(*DWOId));
RangesBase = RangesSectionWriter->getSectionOffset();
DWARFContext *DWOCtx = BC.getDWOContext();
// Setting this CU offset with DWP to normalize DIE offsets to uint32_t
if (DWOCtx && !DWOCtx->getCUIndex().getRows().empty())
DwoDebugInfoPatcher->setDWPOffset((*SplitCU)->getOffset());
DwoDebugInfoPatcher->setRangeBase(*RangesBase);
DwoDebugInfoPatcher->addUnitBaseOffsetLabel((*SplitCU)->getOffset());
DebugAbbrevWriter *DWOAbbrevWriter =
createBinaryDWOAbbrevWriter((*SplitCU)->getContext(), *DWOId);
updateUnitDebugInfo(*(*SplitCU), *DwoDebugInfoPatcher, *DWOAbbrevWriter,
*DebugLocWriter);
DwoDebugInfoPatcher->clearDestinationLabels();
if (!DwoDebugInfoPatcher->getWasRangBasedUsed())
RangesBase = None;
}
{
std::lock_guard<std::mutex> Lock(AccessMutex);
DebugLocWriter = LocListWritersByCU[CUIndex].get();
}
DebugInfoPatcher->addUnitBaseOffsetLabel(Unit->getOffset());
updateUnitDebugInfo(*Unit, *DebugInfoPatcher, *AbbrevWriter,
*DebugLocWriter, RangesBase);
};
if (opts::NoThreads || opts::DeterministicDebugInfo) {
for (std::unique_ptr<DWARFUnit> &CU : BC.DwCtx->compile_units())
processUnitDIE(0, CU.get());
} else {
// Update unit debug info in parallel
ThreadPool &ThreadPool = ParallelUtilities::getThreadPool();
size_t CUIndex = 0;
for (std::unique_ptr<DWARFUnit> &CU : BC.DwCtx->compile_units()) {
ThreadPool.async(processUnitDIE, CUIndex, CU.get());
CUIndex++;
}
ThreadPool.wait();
}
DebugInfoPatcher->clearDestinationLabels();
flushPendingRanges(*DebugInfoPatcher);
CUOffsetMap OffsetMap = finalizeDebugSections(*DebugInfoPatcher);
if (opts::WriteDWP)
writeDWP(DWOIdToName);
else
writeDWOFiles(DWOIdToName);
updateGdbIndexSection(OffsetMap);
}
void DWARFRewriter::updateUnitDebugInfo(
DWARFUnit &Unit, DebugInfoBinaryPatcher &DebugInfoPatcher,
DebugAbbrevWriter &AbbrevWriter, DebugLocWriter &DebugLocWriter,
Optional<uint64_t> RangesBase) {
// Cache debug ranges so that the offset for identical ranges could be reused.
std::map<DebugAddressRangesVector, uint64_t> CachedRanges;
uint64_t DIEOffset = Unit.getOffset() + Unit.getHeaderSize();
uint64_t NextCUOffset = Unit.getNextUnitOffset();
DWARFDebugInfoEntry Die;
DWARFDataExtractor DebugInfoData = Unit.getDebugInfoExtractor();
uint32_t Depth = 0;
while (
DIEOffset < NextCUOffset &&
Die.extractFast(Unit, &DIEOffset, DebugInfoData, NextCUOffset, Depth)) {
if (const DWARFAbbreviationDeclaration *AbbrDecl =
Die.getAbbreviationDeclarationPtr()) {
if (AbbrDecl->hasChildren())
++Depth;
} else {
// NULL entry.
if (Depth > 0)
--Depth;
if (Depth == 0)
break;
}
DWARFDie DIE(&Unit, &Die);
switch (DIE.getTag()) {
case dwarf::DW_TAG_compile_unit: {
auto ModuleRangesOrError = DIE.getAddressRanges();
if (!ModuleRangesOrError) {
consumeError(ModuleRangesOrError.takeError());
break;
}
DWARFAddressRangesVector &ModuleRanges = *ModuleRangesOrError;
DebugAddressRangesVector OutputRanges =
BC.translateModuleAddressRanges(ModuleRanges);
const uint64_t RangesSectionOffset =
RangesSectionWriter->addRanges(OutputRanges);
if (!Unit.isDWOUnit())
ARangesSectionWriter->addCURanges(Unit.getOffset(),
std::move(OutputRanges));
updateDWARFObjectAddressRanges(DIE, RangesSectionOffset, DebugInfoPatcher,
AbbrevWriter, RangesBase);
break;
}
case dwarf::DW_TAG_subprogram: {
// Get function address either from ranges or [LowPC, HighPC) pair.
bool UsesRanges = false;
uint64_t Address;
uint64_t SectionIndex, HighPC;
if (!DIE.getLowAndHighPC(Address, HighPC, SectionIndex)) {
Expected<DWARFAddressRangesVector> RangesOrError =
DIE.getAddressRanges();
if (!RangesOrError) {
consumeError(RangesOrError.takeError());
break;
}
DWARFAddressRangesVector Ranges = *RangesOrError;
// Not a function definition.
if (Ranges.empty())
break;
Address = Ranges.front().LowPC;
UsesRanges = true;
}
// Clear cached ranges as the new function will have its own set.
CachedRanges.clear();
DebugAddressRangesVector FunctionRanges;
if (const BinaryFunction *Function =
BC.getBinaryFunctionAtAddress(Address))
FunctionRanges = Function->getOutputAddressRanges();
// Update ranges.
if (UsesRanges) {
updateDWARFObjectAddressRanges(
DIE, RangesSectionWriter->addRanges(FunctionRanges),
DebugInfoPatcher, AbbrevWriter);
} else {
// Delay conversion of [LowPC, HighPC) into DW_AT_ranges if possible.
const DWARFAbbreviationDeclaration *Abbrev =
DIE.getAbbreviationDeclarationPtr();
assert(Abbrev && "abbrev expected");
// Create a critical section.
static std::shared_timed_mutex CriticalSectionMutex;
std::unique_lock<std::shared_timed_mutex> Lock(CriticalSectionMutex);
if (FunctionRanges.size() > 1) {
convertPending(Unit, Abbrev, DebugInfoPatcher, AbbrevWriter);
// Exit critical section early.
Lock.unlock();
convertToRanges(DIE, FunctionRanges, DebugInfoPatcher);
} else if (ConvertedRangesAbbrevs.find(Abbrev) !=
ConvertedRangesAbbrevs.end()) {
// Exit critical section early.
Lock.unlock();
convertToRanges(DIE, FunctionRanges, DebugInfoPatcher);
} else {
if (FunctionRanges.empty())
FunctionRanges.emplace_back(DebugAddressRange());
addToPendingRanges(Abbrev, DIE, FunctionRanges, Unit.getDWOId());
}
}
break;
}
case dwarf::DW_TAG_lexical_block:
case dwarf::DW_TAG_inlined_subroutine:
case dwarf::DW_TAG_try_block:
case dwarf::DW_TAG_catch_block: {
uint64_t RangesSectionOffset =
RangesSectionWriter->getEmptyRangesOffset();
Expected<DWARFAddressRangesVector> RangesOrError = DIE.getAddressRanges();
const BinaryFunction *Function =
RangesOrError && !RangesOrError->empty()
? BC.getBinaryFunctionContainingAddress(
RangesOrError->front().LowPC)
: nullptr;
if (Function) {
DebugAddressRangesVector OutputRanges =
Function->translateInputToOutputRanges(*RangesOrError);
LLVM_DEBUG(if (OutputRanges.empty() != RangesOrError->empty()) {
dbgs() << "BOLT-DEBUG: problem with DIE at 0x"
<< Twine::utohexstr(DIE.getOffset()) << " in CU at 0x"
<< Twine::utohexstr(Unit.getOffset()) << '\n';
});
RangesSectionOffset = RangesSectionWriter->addRanges(
std::move(OutputRanges), CachedRanges);
} else if (!RangesOrError) {
consumeError(RangesOrError.takeError());
}
updateDWARFObjectAddressRanges(DIE, RangesSectionOffset, DebugInfoPatcher,
AbbrevWriter);
break;
}
default: {
// Handle any tag that can have DW_AT_location attribute.
DWARFFormValue Value;
uint64_t AttrOffset;
if (Optional<AttrInfo> AttrVal =
findAttributeInfo(DIE, dwarf::DW_AT_location)) {
AttrOffset = AttrVal->Offset;
Value = AttrVal->V;
if (Value.isFormClass(DWARFFormValue::FC_Constant) ||
Value.isFormClass(DWARFFormValue::FC_SectionOffset)) {
uint64_t Offset = Value.isFormClass(DWARFFormValue::FC_Constant)
? Value.getAsUnsignedConstant().getValue()
: Value.getAsSectionOffset().getValue();
DebugLocationsVector InputLL;
Optional<object::SectionedAddress> SectionAddress =
Unit.getBaseAddress();
uint64_t BaseAddress = 0;
if (SectionAddress)
BaseAddress = SectionAddress->Address;
Error E = Unit.getLocationTable().visitLocationList(
&Offset, [&](const DWARFLocationEntry &Entry) {
switch (Entry.Kind) {
default:
llvm_unreachable("Unsupported DWARFLocationEntry Kind.");
case dwarf::DW_LLE_end_of_list:
return false;
case dwarf::DW_LLE_base_address:
assert(Entry.SectionIndex == SectionedAddress::UndefSection &&
"absolute address expected");
BaseAddress = Entry.Value0;
break;
case dwarf::DW_LLE_offset_pair:
assert(
(Entry.SectionIndex == SectionedAddress::UndefSection &&
!Unit.isDWOUnit()) &&
"absolute address expected");
InputLL.emplace_back(DebugLocationEntry{
BaseAddress + Entry.Value0, BaseAddress + Entry.Value1,
Entry.Loc});
break;
case dwarf::DW_LLE_startx_length:
assert(Unit.isDWOUnit() &&
"None DWO Unit with DW_LLE_startx_length encoding.");
Optional<object::SectionedAddress> EntryAddress =
Unit.getAddrOffsetSectionItem(Entry.Value0);
assert(EntryAddress && "Address does not exist.");
InputLL.emplace_back(DebugLocationEntry{
EntryAddress->Address,
EntryAddress->Address + Entry.Value1, Entry.Loc});
break;
}
return true;
});
if (E || InputLL.empty()) {
errs() << "BOLT-WARNING: empty location list detected at 0x"
<< Twine::utohexstr(Offset) << " for DIE at 0x"
<< Twine::utohexstr(DIE.getOffset()) << " in CU at 0x"
<< Twine::utohexstr(Unit.getOffset()) << '\n';
} else {
const uint64_t Address = InputLL.front().LowPC;
if (const BinaryFunction *Function =
BC.getBinaryFunctionContainingAddress(Address)) {
DebugLocationsVector OutputLL =
Function->translateInputToOutputLocationList(InputLL);
LLVM_DEBUG(if (OutputLL.empty()) {
dbgs() << "BOLT-DEBUG: location list translated to an empty "
"one at 0x"
<< Twine::utohexstr(DIE.getOffset()) << " in CU at 0x"
<< Twine::utohexstr(Unit.getOffset()) << '\n';
});
DebugLocWriter.addList(AttrOffset, std::move(OutputLL));
}
}
} else {
assert((Value.isFormClass(DWARFFormValue::FC_Exprloc) ||
Value.isFormClass(DWARFFormValue::FC_Block)) &&
"unexpected DW_AT_location form");
if (Unit.isDWOUnit()) {
ArrayRef<uint8_t> Expr = *Value.getAsBlock();
DataExtractor Data(
StringRef((const char *)Expr.data(), Expr.size()),
Unit.getContext().isLittleEndian(), 0);
DWARFExpression LocExpr(Data, Unit.getAddressByteSize(),
Unit.getFormParams().Format);
for (auto &Expr : LocExpr) {
if (Expr.getCode() != dwarf::DW_OP_GNU_addr_index)
continue;
uint64_t Index = Expr.getRawOperand(0);
Optional<object::SectionedAddress> EntryAddress =
Unit.getAddrOffsetSectionItem(Index);
assert(EntryAddress && "Address is not found.");
assert(Index <= std::numeric_limits<uint32_t>::max() &&
"Invalid Operand Index.");
AddrWriter->addIndexAddress(EntryAddress->Address,
static_cast<uint32_t>(Index),
*Unit.getDWOId());
}
}
}
} else if (Optional<AttrInfo> AttrVal =
findAttributeInfo(DIE, dwarf::DW_AT_low_pc)) {
AttrOffset = AttrVal->Offset;
Value = AttrVal->V;
const Optional<uint64_t> Result = Value.getAsAddress();
if (Result.hasValue()) {
const uint64_t Address = Result.getValue();
uint64_t NewAddress = 0;
if (const BinaryFunction *Function =
BC.getBinaryFunctionContainingAddress(Address)) {
NewAddress = Function->translateInputToOutputAddress(Address);
LLVM_DEBUG(dbgs()
<< "BOLT-DEBUG: Fixing low_pc 0x"
<< Twine::utohexstr(Address) << " for DIE with tag "
<< DIE.getTag() << " to 0x"
<< Twine::utohexstr(NewAddress) << '\n');
}
dwarf::Form Form = Value.getForm();
assert(Form != dwarf::DW_FORM_LLVM_addrx_offset &&
"DW_FORM_LLVM_addrx_offset is not supported");
std::lock_guard<std::mutex> Lock(DebugInfoPatcherMutex);
if (Form == dwarf::DW_FORM_GNU_addr_index) {
assert(Unit.isDWOUnit() &&
"DW_FORM_GNU_addr_index in Non DWO unit.");
uint64_t Index = Value.getRawUValue();
// If there is no new address, storing old address.
// Re-using Index to make implementation easier.
// DW_FORM_GNU_addr_index is variable lenght encoding so we either
// have to create indices of same sizes, or use same index.
AddrWriter->addIndexAddress(NewAddress ? NewAddress : Address,
Index, *Unit.getDWOId());
} else {
DebugInfoPatcher.addLE64Patch(AttrOffset, NewAddress);
}
} else if (opts::Verbosity >= 1) {
errs() << "BOLT-WARNING: unexpected form value for attribute at 0x"
<< Twine::utohexstr(AttrOffset);
}
}
}
}
// Handling references.
assert(DIE.isValid() && "Invalid DIE.");
const DWARFAbbreviationDeclaration *AbbrevDecl =
DIE.getAbbreviationDeclarationPtr();
if (!AbbrevDecl)
continue;
uint32_t Index = 0;
for (const DWARFAbbreviationDeclaration::AttributeSpec &Decl :
AbbrevDecl->attributes()) {
switch (Decl.Form) {
default:
break;
case dwarf::DW_FORM_ref1:
case dwarf::DW_FORM_ref2:
case dwarf::DW_FORM_ref4:
case dwarf::DW_FORM_ref8:
case dwarf::DW_FORM_ref_udata:
case dwarf::DW_FORM_ref_addr: {
Optional<AttrInfo> AttrVal = findAttributeInfo(DIE, AbbrevDecl, Index);
uint32_t DestinationAddress =
AttrVal->V.getRawUValue() +
(Decl.Form == dwarf::DW_FORM_ref_addr ? 0 : Unit.getOffset());
DebugInfoPatcher.addReferenceToPatch(
AttrVal->Offset, DestinationAddress, AttrVal->Size, Decl.Form);
// We can have only one reference, and it can be backward one.
DebugInfoPatcher.addDestinationReferenceLabel(DestinationAddress);
break;
}
}
++Index;
}
}
if (DIEOffset > NextCUOffset)
errs() << "BOLT-WARNING: corrupt DWARF detected at 0x"
<< Twine::utohexstr(Unit.getOffset()) << '\n';
}
void DWARFRewriter::updateDWARFObjectAddressRanges(
const DWARFDie DIE, uint64_t DebugRangesOffset,
SimpleBinaryPatcher &DebugInfoPatcher, DebugAbbrevWriter &AbbrevWriter,
Optional<uint64_t> RangesBase) {
// Some objects don't have an associated DIE and cannot be updated (such as
// compiler-generated functions).
if (!DIE)
return;
const DWARFAbbreviationDeclaration *AbbreviationDecl =
DIE.getAbbreviationDeclarationPtr();
if (!AbbreviationDecl) {
if (opts::Verbosity >= 1)
errs() << "BOLT-WARNING: object's DIE doesn't have an abbreviation: "
<< "skipping update. DIE at offset 0x"
<< Twine::utohexstr(DIE.getOffset()) << '\n';
return;
}
if (RangesBase) {
// If DW_AT_GNU_ranges_base is present, update it. No further modifications
// are needed for ranges base.
Optional<AttrInfo> RangesBaseAttrInfo =
findAttributeInfo(DIE, dwarf::DW_AT_GNU_ranges_base);
if (RangesBaseAttrInfo) {
DebugInfoPatcher.addLE32Patch(RangesBaseAttrInfo->Offset,
static_cast<uint32_t>(*RangesBase),
RangesBaseAttrInfo->Size);
RangesBase = None;
}
}
Optional<AttrInfo> LowPCAttrInfo =
findAttributeInfo(DIE, dwarf::DW_AT_low_pc);
if (AbbreviationDecl->findAttributeIndex(dwarf::DW_AT_ranges)) {
// Case 1: The object was already non-contiguous and had DW_AT_ranges.
// In this case we simply need to update the value of DW_AT_ranges
// and introduce DW_AT_GNU_ranges_base if required.
Optional<AttrInfo> AttrVal = findAttributeInfo(DIE, dwarf::DW_AT_ranges);
std::lock_guard<std::mutex> Lock(DebugInfoPatcherMutex);
DebugInfoPatcher.addLE32Patch(
AttrVal->Offset, DebugRangesOffset - DebugInfoPatcher.getRangeBase(),
AttrVal->Size);
if (!RangesBase) {
if (LowPCAttrInfo &&
LowPCAttrInfo->V.getForm() != dwarf::DW_FORM_GNU_addr_index &&
LowPCAttrInfo->V.getForm() != dwarf::DW_FORM_addrx)
DebugInfoPatcher.addLE64Patch(LowPCAttrInfo->Offset, 0);
return;
}
// Convert DW_AT_low_pc into DW_AT_GNU_ranges_base.
if (!LowPCAttrInfo) {
errs() << "BOLT-ERROR: skeleton CU at 0x"
<< Twine::utohexstr(DIE.getOffset())
<< " does not have DW_AT_GNU_ranges_base or DW_AT_low_pc to"
" convert to update ranges base\n";
return;
}
AbbrevWriter.addAttributePatch(
*DIE.getDwarfUnit(), AbbreviationDecl, dwarf::DW_AT_low_pc,
dwarf::DW_AT_GNU_ranges_base, dwarf::DW_FORM_indirect);
DebugInfoPatcher.addUDataPatch(LowPCAttrInfo->Offset, dwarf::DW_FORM_udata,
1);
DebugInfoPatcher.addUDataPatch(LowPCAttrInfo->Offset + 1, *RangesBase, 7);
return;
}
// Case 2: The object has both DW_AT_low_pc and DW_AT_high_pc emitted back
// to back. Replace with new attributes and patch the DIE.
Optional<AttrInfo> HighPCAttrInfo =
findAttributeInfo(DIE, dwarf::DW_AT_high_pc);
if (LowPCAttrInfo && HighPCAttrInfo) {
convertToRangesPatchAbbrev(*DIE.getDwarfUnit(), AbbreviationDecl,
AbbrevWriter, RangesBase);
convertToRangesPatchDebugInfo(DIE, DebugRangesOffset, DebugInfoPatcher,
RangesBase);
} else {
if (opts::Verbosity >= 1)
errs() << "BOLT-ERROR: cannot update ranges for DIE at offset 0x"
<< Twine::utohexstr(DIE.getOffset()) << '\n';
}
}
void DWARFRewriter::updateLineTableOffsets(const MCAsmLayout &Layout) {
ErrorOr<BinarySection &> DbgInfoSection =
BC.getUniqueSectionByName(".debug_info");
ErrorOr<BinarySection &> TypeInfoSection =
BC.getUniqueSectionByName(".debug_types");
assert(((BC.DwCtx->getNumTypeUnits() > 0 && TypeInfoSection) ||
BC.DwCtx->getNumTypeUnits() == 0) &&
"Was not able to retrieve Debug Types section.");
// We will be re-writing .debug_info so relocation mechanism doesn't work for
// Debug Info Patcher.
DebugInfoBinaryPatcher *DebugInfoPatcher = nullptr;
if (BC.DwCtx->getNumCompileUnits()) {
DbgInfoSection->registerPatcher(std::make_unique<DebugInfoBinaryPatcher>());
DebugInfoPatcher =
static_cast<DebugInfoBinaryPatcher *>(DbgInfoSection->getPatcher());
}
// There is no direct connection between CU and TU, but same offsets,
// encoded in DW_AT_stmt_list, into .debug_line get modified.
// We take advantage of that to map original CU line table offsets to new
// ones.
std::unordered_map<uint64_t, uint64_t> DebugLineOffsetMap;
auto GetStatementListValue = [](DWARFUnit *Unit) {
Optional<DWARFFormValue> StmtList =
Unit->getUnitDIE().find(dwarf::DW_AT_stmt_list);
Optional<uint64_t> Offset = dwarf::toSectionOffset(StmtList);
assert(Offset && "Was not able to retreive value of DW_AT_stmt_list.");
return *Offset;
};
const uint64_t Reloc32Type = BC.isAArch64()
? static_cast<uint64_t>(ELF::R_AARCH64_ABS32)
: static_cast<uint64_t>(ELF::R_X86_64_32);
for (const std::unique_ptr<DWARFUnit> &CU : BC.DwCtx->compile_units()) {
const unsigned CUID = CU->getOffset();
MCSymbol *Label = BC.getDwarfLineTable(CUID).getLabel();
if (!Label)
continue;
Optional<AttrInfo> AttrVal =
findAttributeInfo(CU.get()->getUnitDIE(), dwarf::DW_AT_stmt_list);
if (!AttrVal)
continue;
const uint64_t AttributeOffset = AttrVal->Offset;
const uint64_t LineTableOffset = Layout.getSymbolOffset(*Label);
DebugLineOffsetMap[GetStatementListValue(CU.get())] = LineTableOffset;
assert(DbgInfoSection && ".debug_info section must exist");
DebugInfoPatcher->addLE32Patch(AttributeOffset, LineTableOffset);
}
for (const std::unique_ptr<DWARFUnit> &TU : BC.DwCtx->types_section_units()) {
DWARFUnit *Unit = TU.get();
Optional<AttrInfo> AttrVal =
findAttributeInfo(TU.get()->getUnitDIE(), dwarf::DW_AT_stmt_list);
if (!AttrVal)
continue;
const uint64_t AttributeOffset = AttrVal->Offset;
auto Iter = DebugLineOffsetMap.find(GetStatementListValue(Unit));
assert(Iter != DebugLineOffsetMap.end() &&
"Type Unit Updated Line Number Entry does not exist.");
TypeInfoSection->addRelocation(AttributeOffset, nullptr, Reloc32Type,
Iter->second, 0, /*Pending=*/true);
}
// Set .debug_info as finalized so it won't be skipped over when
// we process sections while writing out the new binary. This ensures
// that the pending relocations will be processed and not ignored.
if (DbgInfoSection)
DbgInfoSection->setIsFinalized();
if (TypeInfoSection)
TypeInfoSection->setIsFinalized();
}
CUOffsetMap
DWARFRewriter::finalizeDebugSections(DebugInfoBinaryPatcher &DebugInfoPatcher) {
if (StrWriter->isInitialized()) {
RewriteInstance::addToDebugSectionsToOverwrite(".debug_str");
std::unique_ptr<DebugStrBufferVector> DebugStrSectionContents =
StrWriter->finalize();
BC.registerOrUpdateNoteSection(".debug_str",
copyByteArray(*DebugStrSectionContents),
DebugStrSectionContents->size());
}
std::unique_ptr<DebugBufferVector> RangesSectionContents =
RangesSectionWriter->finalize();
BC.registerOrUpdateNoteSection(".debug_ranges",
copyByteArray(*RangesSectionContents),
RangesSectionContents->size());
std::unique_ptr<DebugBufferVector> LocationListSectionContents =
makeFinalLocListsSection(DebugInfoPatcher);
BC.registerOrUpdateNoteSection(".debug_loc",
copyByteArray(*LocationListSectionContents),
LocationListSectionContents->size());
// AddrWriter should be finalized after debug_loc since more addresses can be
// added there.
if (AddrWriter->isInitialized()) {
AddressSectionBuffer AddressSectionContents = AddrWriter->finalize();
BC.registerOrUpdateNoteSection(".debug_addr",
copyByteArray(AddressSectionContents),
AddressSectionContents.size());
for (auto &CU : BC.DwCtx->compile_units()) {
DWARFDie DIE = CU->getUnitDIE();
if (Optional<AttrInfo> AttrVal =
findAttributeInfo(DIE, dwarf::DW_AT_GNU_addr_base)) {
uint64_t Offset = AddrWriter->getOffset(*CU->getDWOId());
DebugInfoPatcher.addLE32Patch(
AttrVal->Offset, static_cast<int32_t>(Offset), AttrVal->Size);
}
}
}
std::unique_ptr<DebugBufferVector> AbbrevSectionContents =
AbbrevWriter->finalize();
BC.registerOrUpdateNoteSection(".debug_abbrev",
copyByteArray(*AbbrevSectionContents),
AbbrevSectionContents->size());
// Update abbreviation offsets for CUs/TUs if they were changed.
SimpleBinaryPatcher *DebugTypesPatcher = nullptr;
for (auto &Unit : BC.DwCtx->normal_units()) {
const uint64_t NewAbbrevOffset =
AbbrevWriter->getAbbreviationsOffsetForUnit(*Unit);
if (Unit->getAbbreviationsOffset() == NewAbbrevOffset)
continue;
// DWARFv4
// unit_length - 4 bytes
// version - 2 bytes
// So + 6 to patch debug_abbrev_offset
constexpr uint64_t AbbrevFieldOffset = 6;
if (!Unit->isTypeUnit()) {
DebugInfoPatcher.addLE32Patch(Unit->getOffset() + AbbrevFieldOffset,
static_cast<uint32_t>(NewAbbrevOffset));
continue;
}
if (!DebugTypesPatcher) {
ErrorOr<BinarySection &> DebugTypes =
BC.getUniqueSectionByName(".debug_types");
DebugTypes->registerPatcher(std::make_unique<SimpleBinaryPatcher>());
DebugTypesPatcher =
static_cast<SimpleBinaryPatcher *>(DebugTypes->getPatcher());
}
DebugTypesPatcher->addLE32Patch(Unit->getOffset() + AbbrevFieldOffset,
static_cast<uint32_t>(NewAbbrevOffset));
}
// No more creating new DebugInfoPatches.
CUOffsetMap CUMap =
DebugInfoPatcher.computeNewOffsets(*BC.DwCtx.get(), false);
// Skip .debug_aranges if we are re-generating .gdb_index.
if (opts::KeepARanges || !BC.getGdbIndexSection()) {
SmallVector<char, 16> ARangesBuffer;
raw_svector_ostream OS(ARangesBuffer);
auto MAB = std::unique_ptr<MCAsmBackend>(
BC.TheTarget->createMCAsmBackend(*BC.STI, *BC.MRI, MCTargetOptions()));
ARangesSectionWriter->writeARangesSection(OS, CUMap);
const StringRef &ARangesContents = OS.str();
BC.registerOrUpdateNoteSection(".debug_aranges",
copyByteArray(ARangesContents),
ARangesContents.size());
}
return CUMap;
}
// Creates all the data structures necessary for creating MCStreamer.
// They are passed by reference because they need to be kept around.
// Also creates known debug sections. These are sections handled by
// handleDebugDataPatching.
using KnownSectionsEntry = std::pair<MCSection *, DWARFSectionKind>;
namespace {
std::unique_ptr<BinaryContext>
createDwarfOnlyBC(const object::ObjectFile &File) {
return BinaryContext::createBinaryContext(
&File, false,
DWARFContext::create(File, DWARFContext::ProcessDebugRelocations::Ignore,
nullptr, "", WithColor::defaultErrorHandler,
WithColor::defaultWarningHandler));
}
StringMap<KnownSectionsEntry>
createKnownSectionsMap(const MCObjectFileInfo &MCOFI) {
StringMap<KnownSectionsEntry> KnownSectionsTemp = {
{"debug_info.dwo", {MCOFI.getDwarfInfoDWOSection(), DW_SECT_INFO}},
{"debug_types.dwo", {MCOFI.getDwarfTypesDWOSection(), DW_SECT_EXT_TYPES}},
{"debug_str_offsets.dwo",
{MCOFI.getDwarfStrOffDWOSection(), DW_SECT_STR_OFFSETS}},
{"debug_str.dwo", {MCOFI.getDwarfStrDWOSection(), DW_SECT_EXT_unknown}},
{"debug_loc.dwo", {MCOFI.getDwarfLocDWOSection(), DW_SECT_EXT_LOC}},
{"debug_abbrev.dwo", {MCOFI.getDwarfAbbrevDWOSection(), DW_SECT_ABBREV}},
{"debug_line.dwo", {MCOFI.getDwarfLineDWOSection(), DW_SECT_LINE}}};
return KnownSectionsTemp;
}
StringRef getSectionName(const SectionRef &Section) {
Expected<StringRef> SectionName = Section.getName();
assert(SectionName && "Invalid section name.");
StringRef Name = *SectionName;
Name = Name.substr(Name.find_first_not_of("._"));
return Name;
}
// Exctracts an appropriate slice if input is DWP.
// Applies patches or overwrites the section.
Optional<StringRef> updateDebugData(
DWARFContext &DWCtx, std::string &Storage, const SectionRef &Section,
const StringMap<KnownSectionsEntry> &KnownSections, MCStreamer &Streamer,
DWARFRewriter &Writer, const DWARFUnitIndex::Entry *DWOEntry,
uint64_t DWOId, std::unique_ptr<DebugBufferVector> &OutputBuffer) {
auto applyPatch = [&](DebugInfoBinaryPatcher *Patcher,
StringRef Data) -> StringRef {
Patcher->computeNewOffsets(DWCtx, true);
Storage = Patcher->patchBinary(Data);
return StringRef(Storage.c_str(), Storage.size());
};
using DWOSectionContribution =
const DWARFUnitIndex::Entry::SectionContribution;
auto getSliceData = [&](const DWARFUnitIndex::Entry *DWOEntry,
StringRef OutData, DWARFSectionKind Sec,
uint32_t &DWPOffset) -> StringRef {
if (DWOEntry) {
DWOSectionContribution *DWOContrubution = DWOEntry->getContribution(Sec);
DWPOffset = DWOContrubution->Offset;
OutData = OutData.substr(DWPOffset, DWOContrubution->Length);
}
return OutData;
};
StringRef Name = getSectionName(Section);
auto SectionIter = KnownSections.find(Name);
if (SectionIter == KnownSections.end())
return None;
Streamer.SwitchSection(SectionIter->second.first);
Expected<StringRef> Contents = Section.getContents();
assert(Contents && "Invalid contents.");
StringRef OutData = *Contents;
uint32_t DWPOffset = 0;
switch (SectionIter->second.second) {
default: {
if (!Name.equals("debug_str.dwo"))
errs() << "BOLT-WARNING: Unsupported Debug section: " << Name << "\n";
return OutData;
}
case DWARFSectionKind::DW_SECT_INFO: {
OutData = getSliceData(DWOEntry, OutData, DWARFSectionKind::DW_SECT_INFO,
DWPOffset);
DebugInfoBinaryPatcher *Patcher = llvm::cast<DebugInfoBinaryPatcher>(
Writer.getBinaryDWODebugInfoPatcher(DWOId));
return applyPatch(Patcher, OutData);
}
case DWARFSectionKind::DW_SECT_EXT_TYPES: {
return getSliceData(DWOEntry, OutData, DWARFSectionKind::DW_SECT_EXT_TYPES,
DWPOffset);
}
case DWARFSectionKind::DW_SECT_STR_OFFSETS: {
return getSliceData(DWOEntry, OutData,
DWARFSectionKind::DW_SECT_STR_OFFSETS, DWPOffset);
}
case DWARFSectionKind::DW_SECT_ABBREV: {
DebugAbbrevWriter *AbbrevWriter = Writer.getBinaryDWOAbbrevWriter(DWOId);
OutputBuffer = AbbrevWriter->finalize();
// Creating explicit StringRef here, otherwise
// with impicit conversion it will take null byte as end of
// string.
return StringRef(reinterpret_cast<const char *>(OutputBuffer->data()),
OutputBuffer->size());
}
case DWARFSectionKind::DW_SECT_EXT_LOC: {
DebugLocWriter *LocWriter = Writer.getDebugLocWriter(DWOId);
OutputBuffer = LocWriter->getBuffer();
// Creating explicit StringRef here, otherwise
// with impicit conversion it will take null byte as end of
// string.
return StringRef(reinterpret_cast<const char *>(OutputBuffer->data()),
OutputBuffer->size());
}
case DWARFSectionKind::DW_SECT_LINE: {
return getSliceData(DWOEntry, OutData, DWARFSectionKind::DW_SECT_LINE,
DWPOffset);
}
}
}
} // namespace
void DWARFRewriter::writeDWP(
std::unordered_map<uint64_t, std::string> &DWOIdToName) {
SmallString<0> OutputNameStr;
StringRef OutputName;
if (opts::DwarfOutputPath.empty()) {
OutputName =
Twine(opts::OutputFilename).concat(".dwp").toStringRef(OutputNameStr);
} else {
StringRef ExeFileName = llvm::sys::path::filename(opts::OutputFilename);
OutputName = Twine(opts::DwarfOutputPath)
.concat("/")
.concat(ExeFileName)
.concat(".dwp")
.toStringRef(OutputNameStr);
errs() << "BOLT-WARNING: dwarf-output-path is in effect and .dwp file will "
"possibly be written to another location that is not the same as "
"the executable\n";
}
std::error_code EC;
std::unique_ptr<ToolOutputFile> Out =
std::make_unique<ToolOutputFile>(OutputName, EC, sys::fs::OF_None);
const object::ObjectFile *File = BC.DwCtx->getDWARFObj().getFile();
std::unique_ptr<BinaryContext> TmpBC = createDwarfOnlyBC(*File);
std::unique_ptr<MCStreamer> Streamer = TmpBC->createStreamer(Out->os());
const MCObjectFileInfo &MCOFI = *Streamer->getContext().getObjectFileInfo();
StringMap<KnownSectionsEntry> KnownSections = createKnownSectionsMap(MCOFI);
MCSection *const StrSection = MCOFI.getDwarfStrDWOSection();
MCSection *const StrOffsetSection = MCOFI.getDwarfStrOffDWOSection();
// Data Structures for DWP book keeping
// Size of array corresponds to the number of sections supported by DWO format
// in DWARF4/5.
uint32_t ContributionOffsets[8] = {};
std::deque<SmallString<32>> UncompressedSections;
DWPStringPool Strings(*Streamer, StrSection);
MapVector<uint64_t, UnitIndexEntry> IndexEntries;
constexpr uint32_t IndexVersion = 2;
// Setup DWP code once.
DWARFContext *DWOCtx = BC.getDWOContext();
const DWARFUnitIndex *CUIndex = nullptr;
bool IsDWP = false;
if (DWOCtx) {
CUIndex = &DWOCtx->getCUIndex();
IsDWP = !CUIndex->getRows().empty();
}
for (const std::unique_ptr<DWARFUnit> &CU : BC.DwCtx->compile_units()) {
Optional<uint64_t> DWOId = CU->getDWOId();
if (!DWOId)
continue;
// Skipping CUs that we failed to load.
Optional<DWARFUnit *> DWOCU = BC.getDWOCU(*DWOId);
if (!DWOCU)
continue;
assert(CU->getVersion() == 4 && "For DWP output only DWARF4 is supported");
UnitIndexEntry CurEntry = {};
CurEntry.DWOName =
dwarf::toString(CU->getUnitDIE().find(
{dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}),
"");
const char *Name = CU->getUnitDIE().getShortName();
if (Name)
CurEntry.Name = Name;
StringRef CurStrSection;
StringRef CurStrOffsetSection;
// This maps each section contained in this file to its length.
// This information is later on used to calculate the contributions,
// i.e. offset and length, of each compile/type unit to a section.
std::vector<std::pair<DWARFSectionKind, uint32_t>> SectionLength;
const DWARFUnitIndex::Entry *DWOEntry = nullptr;
if (IsDWP)
DWOEntry = CUIndex->getFromHash(*DWOId);
bool StrSectionWrittenOut = false;
const object::ObjectFile *DWOFile =
(*DWOCU)->getContext().getDWARFObj().getFile();
for (const SectionRef &Section : DWOFile->sections()) {
std::string Storage = "";
std::unique_ptr<DebugBufferVector> OutputData;
Optional<StringRef> TOutData = updateDebugData(
(*DWOCU)->getContext(), Storage, Section, KnownSections, *Streamer,
*this, DWOEntry, *DWOId, OutputData);
if (!TOutData)
continue;
StringRef OutData = *TOutData;
StringRef Name = getSectionName(Section);
if (Name.equals("debug_str.dwo")) {
CurStrSection = OutData;
} else {
// Since handleDebugDataPatching returned true, we already know this is
// a known section.
auto SectionIter = KnownSections.find(Name);
if (SectionIter->second.second == DWARFSectionKind::DW_SECT_STR_OFFSETS)
CurStrOffsetSection = OutData;
else
Streamer->emitBytes(OutData);
auto Index =
getContributionIndex(SectionIter->second.second, IndexVersion);
CurEntry.Contributions[Index].Offset = ContributionOffsets[Index];
CurEntry.Contributions[Index].Length = OutData.size();
ContributionOffsets[Index] += CurEntry.Contributions[Index].Length;
}
// Strings are combined in to a new string section, and de-duplicated
// based on hash.
if (!StrSectionWrittenOut && !CurStrOffsetSection.empty() &&
!CurStrSection.empty()) {
writeStringsAndOffsets(*Streamer.get(), Strings, StrOffsetSection,
CurStrSection, CurStrOffsetSection,
CU->getVersion());
StrSectionWrittenOut = true;
}
}
CompileUnitIdentifiers CUI{*DWOId, CurEntry.Name.c_str(),
CurEntry.DWOName.c_str()};
auto P = IndexEntries.insert(std::make_pair(CUI.Signature, CurEntry));
if (!P.second) {
Error Err = buildDuplicateError(*P.first, CUI, "");
errs() << "BOLT-ERROR: " << toString(std::move(Err)) << "\n";
return;
}
}
// Lie about the type contribution for DWARF < 5. In DWARFv5 the type
// section does not exist, so no need to do anything about this.
ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES, 2)] = 0;
writeIndex(*Streamer.get(), MCOFI.getDwarfCUIndexSection(),
ContributionOffsets, IndexEntries, IndexVersion);
Streamer->Finish();
Out->keep();
}
void DWARFRewriter::writeDWOFiles(
std::unordered_map<uint64_t, std::string> &DWOIdToName) {
// Setup DWP code once.
DWARFContext *DWOCtx = BC.getDWOContext();
const DWARFUnitIndex *CUIndex = nullptr;
bool IsDWP = false;
if (DWOCtx) {
CUIndex = &DWOCtx->getCUIndex();
IsDWP = !CUIndex->getRows().empty();
}
for (const std::unique_ptr<DWARFUnit> &CU : BC.DwCtx->compile_units()) {
Optional<uint64_t> DWOId = CU->getDWOId();
if (!DWOId)
continue;
// Skipping CUs that we failed to load.
Optional<DWARFUnit *> DWOCU = BC.getDWOCU(*DWOId);
if (!DWOCU)
continue;
std::string CompDir = opts::DwarfOutputPath.empty()
? CU->getCompilationDir()
: opts::DwarfOutputPath.c_str();
std::string ObjectName = getDWOName(*CU.get(), nullptr, DWOIdToName);
auto FullPath = CompDir.append("/").append(ObjectName);
std::error_code EC;
std::unique_ptr<ToolOutputFile> TempOut =
std::make_unique<ToolOutputFile>(FullPath, EC, sys::fs::OF_None);
const DWARFUnitIndex::Entry *DWOEntry = nullptr;
if (IsDWP)
DWOEntry = CUIndex->getFromHash(*DWOId);
const object::ObjectFile *File =
(*DWOCU)->getContext().getDWARFObj().getFile();
std::unique_ptr<BinaryContext> TmpBC = createDwarfOnlyBC(*File);
std::unique_ptr<MCStreamer> Streamer = TmpBC->createStreamer(TempOut->os());
StringMap<KnownSectionsEntry> KnownSections =
createKnownSectionsMap(*Streamer->getContext().getObjectFileInfo());
for (const SectionRef &Section : File->sections()) {
std::string Storage = "";
std::unique_ptr<DebugBufferVector> OutputData;
if (Optional<StringRef> OutData = updateDebugData(
(*DWOCU)->getContext(), Storage, Section, KnownSections,
*Streamer, *this, DWOEntry, *DWOId, OutputData))
Streamer->emitBytes(*OutData);
}
Streamer->Finish();
TempOut->keep();
}
}
void DWARFRewriter::updateGdbIndexSection(CUOffsetMap &CUMap) {
if (!BC.getGdbIndexSection())
return;
// See https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html
// for .gdb_index section format.
StringRef GdbIndexContents = BC.getGdbIndexSection()->getContents();
const char *Data = GdbIndexContents.data();
// Parse the header.
const uint32_t Version = read32le(Data);
if (Version != 7 && Version != 8) {
errs() << "BOLT-ERROR: can only process .gdb_index versions 7 and 8\n";
exit(1);
}
// Some .gdb_index generators use file offsets while others use section
// offsets. Hence we can only rely on offsets relative to each other,
// and ignore their absolute values.
const uint32_t CUListOffset = read32le(Data + 4);
const uint32_t CUTypesOffset = read32le(Data + 8);
const uint32_t AddressTableOffset = read32le(Data + 12);
const uint32_t SymbolTableOffset = read32le(Data + 16);
const uint32_t ConstantPoolOffset = read32le(Data + 20);
Data += 24;
// Map CUs offsets to indices and verify existing index table.
std::map<uint32_t, uint32_t> OffsetToIndexMap;
const uint32_t CUListSize = CUTypesOffset - CUListOffset;
const unsigned NumCUs = BC.DwCtx->getNumCompileUnits();
if (CUListSize != NumCUs * 16) {
errs() << "BOLT-ERROR: .gdb_index: CU count mismatch\n";
exit(1);
}
for (unsigned Index = 0; Index < NumCUs; ++Index, Data += 16) {
const DWARFUnit *CU = BC.DwCtx->getUnitAtIndex(Index);
const uint64_t Offset = read64le(Data);
if (CU->getOffset() != Offset) {
errs() << "BOLT-ERROR: .gdb_index CU offset mismatch\n";
exit(1);
}
OffsetToIndexMap[Offset] = Index;
}
// Ignore old address table.
const uint32_t OldAddressTableSize = SymbolTableOffset - AddressTableOffset;
// Move Data to the beginning of symbol table.
Data += SymbolTableOffset - CUTypesOffset;
// Calculate the size of the new address table.
uint32_t NewAddressTableSize = 0;
for (const auto &CURangesPair : ARangesSectionWriter->getCUAddressRanges()) {
const SmallVector<DebugAddressRange, 2> &Ranges = CURangesPair.second;
NewAddressTableSize += Ranges.size() * 20;
}
// Difference between old and new table (and section) sizes.
// Could be negative.
int32_t Delta = NewAddressTableSize - OldAddressTableSize;
size_t NewGdbIndexSize = GdbIndexContents.size() + Delta;
// Free'd by ExecutableFileMemoryManager.
auto *NewGdbIndexContents = new uint8_t[NewGdbIndexSize];
uint8_t *Buffer = NewGdbIndexContents;
write32le(Buffer, Version);
write32le(Buffer + 4, CUListOffset);
write32le(Buffer + 8, CUTypesOffset);
write32le(Buffer + 12, AddressTableOffset);
write32le(Buffer + 16, SymbolTableOffset + Delta);
write32le(Buffer + 20, ConstantPoolOffset + Delta);
Buffer += 24;
// Writing out CU List <Offset, Size>
for (auto &CUInfo : CUMap) {
write64le(Buffer, CUInfo.second.Offset);
// Length encoded in CU doesn't contain first 4 bytes that encode length.
write64le(Buffer + 8, CUInfo.second.Length + 4);
Buffer += 16;
}
// Copy over types CU list
// Spec says " triplet, the first value is the CU offset, the second value is
// the type offset in the CU, and the third value is the type signature"
// Looking at what is being generated by gdb-add-index. The first entry is TU
// offset, second entry is offset from it, and third entry is the type
// signature.
memcpy(Buffer, GdbIndexContents.data() + CUTypesOffset,
AddressTableOffset - CUTypesOffset);
Buffer += AddressTableOffset - CUTypesOffset;
// Generate new address table.
for (const std::pair<const uint64_t, DebugAddressRangesVector> &CURangesPair :
ARangesSectionWriter->getCUAddressRanges()) {
const uint32_t CUIndex = OffsetToIndexMap[CURangesPair.first];
const DebugAddressRangesVector &Ranges = CURangesPair.second;
for (const DebugAddressRange &Range : Ranges) {
write64le(Buffer, Range.LowPC);
write64le(Buffer + 8, Range.HighPC);
write32le(Buffer + 16, CUIndex);
Buffer += 20;
}
}
const size_t TrailingSize =
GdbIndexContents.data() + GdbIndexContents.size() - Data;
assert(Buffer + TrailingSize == NewGdbIndexContents + NewGdbIndexSize &&
"size calculation error");
// Copy over the rest of the original data.
memcpy(Buffer, Data, TrailingSize);
// Register the new section.
BC.registerOrUpdateNoteSection(".gdb_index", NewGdbIndexContents,
NewGdbIndexSize);
}
void DWARFRewriter::convertToRanges(DWARFDie DIE,
const DebugAddressRangesVector &Ranges,
SimpleBinaryPatcher &DebugInfoPatcher) {
uint64_t RangesSectionOffset;
if (Ranges.empty())
RangesSectionOffset = RangesSectionWriter->getEmptyRangesOffset();
else
RangesSectionOffset = RangesSectionWriter->addRanges(Ranges);
convertToRangesPatchDebugInfo(DIE, RangesSectionOffset, DebugInfoPatcher);
}
void DWARFRewriter::convertPending(const DWARFUnit &Unit,
const DWARFAbbreviationDeclaration *Abbrev,
SimpleBinaryPatcher &DebugInfoPatcher,
DebugAbbrevWriter &AbbrevWriter) {
if (ConvertedRangesAbbrevs.count(Abbrev))
return;
convertToRangesPatchAbbrev(Unit, Abbrev, AbbrevWriter);
auto I = PendingRanges.find(Abbrev);
if (I != PendingRanges.end()) {
for (std::pair<DWARFDieWrapper, DebugAddressRange> &Pair : I->second)
convertToRanges(Pair.first, {Pair.second}, DebugInfoPatcher);
PendingRanges.erase(I);
}
ConvertedRangesAbbrevs.emplace(Abbrev);
}
void DWARFRewriter::addToPendingRanges(
const DWARFAbbreviationDeclaration *Abbrev, DWARFDie DIE,
DebugAddressRangesVector &FunctionRanges, Optional<uint64_t> DWOId) {
Optional<DWARFFormValue> LowPcValue = DIE.find(dwarf::DW_AT_low_pc);
Optional<DWARFFormValue> HighPcValue = DIE.find(dwarf::DW_AT_high_pc);
if (LowPcValue &&
LowPcValue->getForm() == dwarf::Form::DW_FORM_GNU_addr_index) {
assert(DWOId && "Invalid DWO ID.");
(void)DWOId;
assert(HighPcValue && "Low PC exists, but not High PC.");
(void)HighPcValue;
uint64_t IndexL = LowPcValue->getRawUValue();
uint64_t IndexH = HighPcValue->getRawUValue();
for (auto Address : FunctionRanges) {
AddrWriter->addIndexAddress(Address.LowPC, IndexL, *DWOId);
// 2.17.2
// If the value of the DW_AT_high_pc is of class address, it is the
// relocated address of the first location past the last instruction
// associated with the entity; if it is of class constant, the value is
// an unsigned integer offset which when added to the low PC gives the
// address of the first location past the last instruction associated
// with the entity.
if (!HighPcValue->isFormClass(DWARFFormValue::FC_Constant))
AddrWriter->addIndexAddress(Address.HighPC, IndexH, *DWOId);
}
}
PendingRanges[Abbrev].emplace_back(
std::make_pair(DWARFDieWrapper(DIE), FunctionRanges.front()));
}
std::unique_ptr<DebugBufferVector>
DWARFRewriter::makeFinalLocListsSection(SimpleBinaryPatcher &DebugInfoPatcher) {
auto LocBuffer = std::make_unique<DebugBufferVector>();
auto LocStream = std::make_unique<raw_svector_ostream>(*LocBuffer);
auto Writer =
std::unique_ptr<MCObjectWriter>(BC.createObjectWriter(*LocStream));
uint64_t SectionOffset = 0;
// Add an empty list as the first entry;
const char Zeroes[16] = {0};
*LocStream << StringRef(Zeroes, 16);
SectionOffset += 2 * 8;
for (std::pair<const uint64_t, std::unique_ptr<DebugLocWriter>> &Loc :
LocListWritersByCU) {
DebugLocWriter *LocWriter = Loc.second.get();
if (auto *LocListWriter = llvm::dyn_cast<DebugLoclistWriter>(LocWriter)) {
SimpleBinaryPatcher *Patcher =
getBinaryDWODebugInfoPatcher(LocListWriter->getDWOID());
LocListWriter->finalize(0, *Patcher);
continue;
}
LocWriter->finalize(SectionOffset, DebugInfoPatcher);
std::unique_ptr<DebugBufferVector> CurrCULocationLists =
LocWriter->getBuffer();
*LocStream << *CurrCULocationLists;
SectionOffset += CurrCULocationLists->size();
}
return LocBuffer;
}
void DWARFRewriter::flushPendingRanges(SimpleBinaryPatcher &DebugInfoPatcher) {
for (std::pair<const DWARFAbbreviationDeclaration *const,
std::vector<std::pair<DWARFDieWrapper, DebugAddressRange>>>
&I : PendingRanges)
for (std::pair<DWARFDieWrapper, DebugAddressRange> &RangePair : I.second)
patchLowHigh(RangePair.first, RangePair.second, DebugInfoPatcher);
clearList(PendingRanges);
}
namespace {
void getRangeAttrData(DWARFDie DIE, Optional<AttrInfo> &LowPCVal,
Optional<AttrInfo> &HighPCVal) {
LowPCVal = findAttributeInfo(DIE, dwarf::DW_AT_low_pc);
HighPCVal = findAttributeInfo(DIE, dwarf::DW_AT_high_pc);
uint64_t LowPCOffset = LowPCVal->Offset;
uint64_t HighPCOffset = HighPCVal->Offset;
dwarf::Form LowPCForm = LowPCVal->V.getForm();
dwarf::Form HighPCForm = HighPCVal->V.getForm();
if (LowPCForm != dwarf::DW_FORM_addr &&
LowPCForm != dwarf::DW_FORM_GNU_addr_index) {
errs() << "BOLT-WARNING: unexpected low_pc form value. Cannot update DIE "
<< "at offset 0x" << Twine::utohexstr(DIE.getOffset()) << "\n";
return;
}
if (HighPCForm != dwarf::DW_FORM_addr && HighPCForm != dwarf::DW_FORM_data8 &&
HighPCForm != dwarf::DW_FORM_data4 &&
HighPCForm != dwarf::DW_FORM_data2 &&
HighPCForm != dwarf::DW_FORM_data1 &&
HighPCForm != dwarf::DW_FORM_udata) {
errs() << "BOLT-WARNING: unexpected high_pc form value. Cannot update DIE "
<< "at offset 0x" << Twine::utohexstr(DIE.getOffset()) << "\n";
return;
}
if ((LowPCOffset == -1U || (LowPCOffset + 8 != HighPCOffset)) &&
LowPCForm != dwarf::DW_FORM_GNU_addr_index) {
errs() << "BOLT-WARNING: high_pc expected immediately after low_pc. "
<< "Cannot update DIE at offset 0x"
<< Twine::utohexstr(DIE.getOffset()) << '\n';
return;
}
}
} // namespace
void DWARFRewriter::patchLowHigh(DWARFDie DIE, DebugAddressRange Range,
SimpleBinaryPatcher &DebugInfoPatcher) {
Optional<AttrInfo> LowPCVal = None;
Optional<AttrInfo> HighPCVal = None;
getRangeAttrData(DIE, LowPCVal, HighPCVal);
uint64_t LowPCOffset = LowPCVal->Offset;
uint64_t HighPCOffset = HighPCVal->Offset;
auto *TempDebugPatcher = &DebugInfoPatcher;
if (LowPCVal->V.getForm() == dwarf::DW_FORM_GNU_addr_index) {
DWARFUnit *Unit = DIE.getDwarfUnit();
assert(Unit->isDWOUnit() && "DW_FORM_GNU_addr_index not part of DWO.");
uint32_t AddressIndex =
AddrWriter->getIndexFromAddress(Range.LowPC, *Unit->getDWOId());
TempDebugPatcher = getBinaryDWODebugInfoPatcher(*Unit->getDWOId());
TempDebugPatcher->addUDataPatch(LowPCOffset, AddressIndex,
std::abs(int(HighPCOffset - LowPCOffset)));
// TODO: In DWARF5 support ULEB128 for high_pc
} else {
TempDebugPatcher->addLE64Patch(LowPCOffset, Range.LowPC);
}
uint64_t HighPC = Range.HighPC;
// The DW_FORM_data* is delta between high and low pc
if (HighPCVal->V.getForm() != dwarf::Form::DW_FORM_addr)
HighPC -= Range.LowPC;
if (isHighPcFormEightBytes(HighPCVal->V.getForm()))
TempDebugPatcher->addLE64Patch(HighPCOffset, HighPC);
else
TempDebugPatcher->addLE32Patch(HighPCOffset, HighPC);
}
void DWARFRewriter::convertToRangesPatchAbbrev(
const DWARFUnit &Unit, const DWARFAbbreviationDeclaration *Abbrev,
DebugAbbrevWriter &AbbrevWriter, Optional<uint64_t> RangesBase) {
auto getAttributeForm = [&Abbrev](const dwarf::Attribute Attr) {
Optional<uint32_t> Index = Abbrev->findAttributeIndex(Attr);
assert(Index && "attribute not found");
return Abbrev->getFormByIndex(*Index);
};
dwarf::Form LowPCForm = getAttributeForm(dwarf::DW_AT_low_pc);
// DW_FORM_GNU_addr_index is already variable encoding so nothing to do
// there.
if (RangesBase) {
assert(LowPCForm != dwarf::DW_FORM_GNU_addr_index);
AbbrevWriter.addAttributePatch(Unit, Abbrev, dwarf::DW_AT_low_pc,
dwarf::DW_AT_GNU_ranges_base,
dwarf::DW_FORM_sec_offset);
}
AbbrevWriter.addAttributePatch(Unit, Abbrev, dwarf::DW_AT_high_pc,
dwarf::DW_AT_ranges,
dwarf::DW_FORM_sec_offset);
}
void DWARFRewriter::convertToRangesPatchDebugInfo(
DWARFDie DIE, uint64_t RangesSectionOffset,
SimpleBinaryPatcher &DebugInfoPatcher, Optional<uint64_t> RangesBase) {
Optional<AttrInfo> LowPCVal = None;
Optional<AttrInfo> HighPCVal = None;
getRangeAttrData(DIE, LowPCVal, HighPCVal);
uint64_t LowPCOffset = LowPCVal->Offset;
uint64_t HighPCOffset = HighPCVal->Offset;
std::lock_guard<std::mutex> Lock(DebugInfoPatcherMutex);
uint32_t BaseOffset = 0;
if (LowPCVal->V.getForm() == dwarf::DW_FORM_GNU_addr_index) {
// Use ULEB128 for the value.
DebugInfoPatcher.addUDataPatch(LowPCOffset, 0,
std::abs(int(HighPCOffset - LowPCOffset)));
// Ranges are relative to DW_AT_GNU_ranges_base.
BaseOffset = DebugInfoPatcher.getRangeBase();
} else {
// If case DW_AT_low_pc was converted into DW_AT_GNU_ranges_base
if (RangesBase)
DebugInfoPatcher.addLE32Patch(LowPCOffset, *RangesBase, 8);
else
DebugInfoPatcher.addLE64Patch(LowPCOffset, 0);
}
DebugInfoPatcher.addLE32Patch(HighPCOffset, RangesSectionOffset - BaseOffset,
HighPCVal->Size);
}
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