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clang-p2996/bolt/lib/Rewrite/DWARFRewriter.cpp
Alexander Yermolovich bd1ebe9d04 [BOLT][DWARF] Add ability to insert new entries in to DIE 
Added ability to append new entries to DIE. This is useful to standadize DWARF4
Split Dwarf, and simplify implementation of DWARF5.
Multiple DIEs can share an abbrev. So currently limitation is that only unique
Attributes can be added.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D119577
2022-02-15 18:07:19 -08:00

1457 lines
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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/DWARFDebugLoc.h"
#include "llvm/DebugInfo/DWARF/DWARFExpression.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);
}
namespace llvm {
namespace bolt {
/// 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);
}
} // namespace bolt
} // namespace llvm
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();
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.
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;
}
// 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();
if (FunctionRanges.empty())
FunctionRanges.push_back({0, 0});
updateDWARFObjectAddressRanges(
DIE, RangesSectionWriter->addRanges(FunctionRanges), DebugInfoPatcher,
AbbrevWriter);
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.addAttribute(*DIE.getDwarfUnit(), AbbreviationDecl,
dwarf::DW_AT_GNU_ranges_base,
dwarf::DW_FORM_sec_offset);
reinterpret_cast<DebugInfoBinaryPatcher &>(DebugInfoPatcher)
.insertNewEntry(DIE, *RangesBase);
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);
}
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;
}
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<uint64_t> DWOId) {
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) {
uint32_t AddressIndex =
AddrWriter->getIndexFromAddress(Range.LowPC, *DWOId);
TempDebugPatcher = getBinaryDWODebugInfoPatcher(*DWOId);
TempDebugPatcher->addUDataPatch(LowPCOffset, AddressIndex, LowPCVal->Size);
// 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 (!HighPCVal->V.isFormClass(DWARFFormValue::FC_Constant)) {
AddressIndex = AddrWriter->getIndexFromAddress(Range.HighPC, *DWOId);
TempDebugPatcher->addUDataPatch(HighPCOffset, AddressIndex,
HighPCVal->Size);
}
} 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.addAttribute(Unit, Abbrev, 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 {
DebugInfoPatcher.addLE64Patch(LowPCOffset, 0);
// If DW_AT_GNU_ranges_base was inserted.
if (RangesBase)
reinterpret_cast<DebugInfoBinaryPatcher &>(DebugInfoPatcher)
.insertNewEntry(DIE, *RangesBase);
}
DebugInfoPatcher.addLE32Patch(HighPCOffset, RangesSectionOffset - BaseOffset,
HighPCVal->Size);
}
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