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llvm-project/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp

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//===- DWARFUnit.cpp ------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
#include "llvm/DebugInfo/DWARF/DWARFDie.h"
#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/WithColor.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <utility>
#include <vector>
using namespace llvm;
using namespace dwarf;
void DWARFUnitSectionBase::parse(DWARFContext &C, const DWARFSection &Section) {
const DWARFObject &D = C.getDWARFObj();
parseImpl(C, D, Section, C.getDebugAbbrev(), &D.getRangeSection(),
D.getStringSection(), D.getStringOffsetSection(),
&D.getAddrSection(), D.getLineSection(), D.isLittleEndian(), false,
false);
}
void DWARFUnitSectionBase::parseDWO(DWARFContext &C,
const DWARFSection &DWOSection, bool Lazy) {
const DWARFObject &D = C.getDWARFObj();
parseImpl(C, D, DWOSection, C.getDebugAbbrevDWO(), &D.getRangeDWOSection(),
D.getStringDWOSection(), D.getStringOffsetDWOSection(),
&D.getAddrSection(), D.getLineDWOSection(), C.isLittleEndian(),
true, Lazy);
}
DWARFUnit::DWARFUnit(DWARFContext &DC, const DWARFSection &Section,
const DWARFDebugAbbrev *DA, const DWARFSection *RS,
StringRef SS, const DWARFSection &SOS,
const DWARFSection *AOS, const DWARFSection &LS, bool LE,
bool IsDWO, const DWARFUnitSectionBase &UnitSection,
const DWARFUnitIndex::Entry *IndexEntry)
: Context(DC), InfoSection(Section), Abbrev(DA), RangeSection(RS),
LineSection(LS), StringSection(SS), StringOffsetSection(SOS),
AddrOffsetSection(AOS), isLittleEndian(LE), isDWO(IsDWO),
UnitSection(UnitSection), IndexEntry(IndexEntry) {
clear();
}
DWARFUnit::~DWARFUnit() = default;
DWARFDataExtractor DWARFUnit::getDebugInfoExtractor() const {
return DWARFDataExtractor(Context.getDWARFObj(), InfoSection, isLittleEndian,
getAddressByteSize());
}
bool DWARFUnit::getAddrOffsetSectionItem(uint32_t Index,
uint64_t &Result) const {
uint32_t Offset = AddrOffsetSectionBase + Index * getAddressByteSize();
if (AddrOffsetSection->Data.size() < Offset + getAddressByteSize())
return false;
DWARFDataExtractor DA(Context.getDWARFObj(), *AddrOffsetSection,
isLittleEndian, getAddressByteSize());
Result = DA.getRelocatedAddress(&Offset);
return true;
}
bool DWARFUnit::getStringOffsetSectionItem(uint32_t Index,
uint64_t &Result) const {
if (!StringOffsetsTableContribution)
return false;
unsigned ItemSize = getDwarfStringOffsetsByteSize();
uint32_t Offset = getStringOffsetsBase() + Index * ItemSize;
if (StringOffsetSection.Data.size() < Offset + ItemSize)
return false;
DWARFDataExtractor DA(Context.getDWARFObj(), StringOffsetSection,
isLittleEndian, 0);
Result = DA.getRelocatedValue(ItemSize, &Offset);
return true;
}
bool DWARFUnit::extractImpl(const DWARFDataExtractor &debug_info,
uint32_t *offset_ptr) {
Length = debug_info.getU32(offset_ptr);
// FIXME: Support DWARF64.
FormParams.Format = DWARF32;
FormParams.Version = debug_info.getU16(offset_ptr);
if (FormParams.Version >= 5) {
UnitType = debug_info.getU8(offset_ptr);
FormParams.AddrSize = debug_info.getU8(offset_ptr);
AbbrOffset = debug_info.getU32(offset_ptr);
} else {
AbbrOffset = debug_info.getRelocatedValue(4, offset_ptr);
FormParams.AddrSize = debug_info.getU8(offset_ptr);
}
if (IndexEntry) {
if (AbbrOffset)
return false;
auto *UnitContrib = IndexEntry->getOffset();
if (!UnitContrib || UnitContrib->Length != (Length + 4))
return false;
auto *AbbrEntry = IndexEntry->getOffset(DW_SECT_ABBREV);
if (!AbbrEntry)
return false;
AbbrOffset = AbbrEntry->Offset;
}
bool LengthOK = debug_info.isValidOffset(getNextUnitOffset() - 1);
bool VersionOK = DWARFContext::isSupportedVersion(getVersion());
bool AddrSizeOK = getAddressByteSize() == 4 || getAddressByteSize() == 8;
if (!LengthOK || !VersionOK || !AddrSizeOK)
return false;
// Keep track of the highest DWARF version we encounter across all units.
Context.setMaxVersionIfGreater(getVersion());
return true;
}
bool DWARFUnit::extract(const DWARFDataExtractor &debug_info,
uint32_t *offset_ptr) {
clear();
Offset = *offset_ptr;
if (debug_info.isValidOffset(*offset_ptr)) {
if (extractImpl(debug_info, offset_ptr))
return true;
// reset the offset to where we tried to parse from if anything went wrong
*offset_ptr = Offset;
}
return false;
}
bool DWARFUnit::extractRangeList(uint32_t RangeListOffset,
DWARFDebugRangeList &RangeList) const {
// Require that compile unit is extracted.
assert(!DieArray.empty());
DWARFDataExtractor RangesData(Context.getDWARFObj(), *RangeSection,
isLittleEndian, getAddressByteSize());
uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
return RangeList.extract(RangesData, &ActualRangeListOffset);
}
void DWARFUnit::clear() {
Offset = 0;
Length = 0;
Abbrevs = nullptr;
FormParams = dwarf::FormParams({0, 0, DWARF32});
BaseAddr.reset();
RangeSectionBase = 0;
AddrOffsetSectionBase = 0;
clearDIEs(false);
DWO.reset();
}
const char *DWARFUnit::getCompilationDir() {
return dwarf::toString(getUnitDIE().find(DW_AT_comp_dir), nullptr);
}
Optional<uint64_t> DWARFUnit::getDWOId() {
return toUnsigned(getUnitDIE().find(DW_AT_GNU_dwo_id));
}
void DWARFUnit::extractDIEsToVector(
bool AppendCUDie, bool AppendNonCUDies,
std::vector<DWARFDebugInfoEntry> &Dies) const {
if (!AppendCUDie && !AppendNonCUDies)
return;
// Set the offset to that of the first DIE and calculate the start of the
// next compilation unit header.
uint32_t DIEOffset = Offset + getHeaderSize();
uint32_t NextCUOffset = getNextUnitOffset();
DWARFDebugInfoEntry DIE;
DWARFDataExtractor DebugInfoData = getDebugInfoExtractor();
uint32_t Depth = 0;
bool IsCUDie = true;
while (DIE.extractFast(*this, &DIEOffset, DebugInfoData, NextCUOffset,
Depth)) {
if (IsCUDie) {
if (AppendCUDie)
Dies.push_back(DIE);
if (!AppendNonCUDies)
break;
// The average bytes per DIE entry has been seen to be
// around 14-20 so let's pre-reserve the needed memory for
// our DIE entries accordingly.
Dies.reserve(Dies.size() + getDebugInfoSize() / 14);
IsCUDie = false;
} else {
Dies.push_back(DIE);
}
if (const DWARFAbbreviationDeclaration *AbbrDecl =
DIE.getAbbreviationDeclarationPtr()) {
// Normal DIE
if (AbbrDecl->hasChildren())
++Depth;
} else {
// NULL DIE.
if (Depth > 0)
--Depth;
if (Depth == 0)
break; // We are done with this compile unit!
}
}
// Give a little bit of info if we encounter corrupt DWARF (our offset
// should always terminate at or before the start of the next compilation
// unit header).
if (DIEOffset > NextCUOffset)
WithColor::warning() << format("DWARF compile unit extends beyond its "
"bounds cu 0x%8.8x at 0x%8.8x\n",
getOffset(), DIEOffset);
}
size_t DWARFUnit::extractDIEsIfNeeded(bool CUDieOnly) {
if ((CUDieOnly && !DieArray.empty()) ||
DieArray.size() > 1)
return 0; // Already parsed.
bool HasCUDie = !DieArray.empty();
extractDIEsToVector(!HasCUDie, !CUDieOnly, DieArray);
if (DieArray.empty())
return 0;
// If CU DIE was just parsed, copy several attribute values from it.
if (!HasCUDie) {
DWARFDie UnitDie = getUnitDIE();
Optional<DWARFFormValue> PC = UnitDie.find({DW_AT_low_pc, DW_AT_entry_pc});
if (Optional<uint64_t> Addr = toAddress(PC))
setBaseAddress({*Addr, PC->getSectionIndex()});
if (!isDWO) {
assert(AddrOffsetSectionBase == 0);
assert(RangeSectionBase == 0);
AddrOffsetSectionBase =
toSectionOffset(UnitDie.find(DW_AT_GNU_addr_base), 0);
RangeSectionBase = toSectionOffset(UnitDie.find(DW_AT_rnglists_base), 0);
}
// In general, in DWARF v5 and beyond we derive the start of the unit's
// contribution to the string offsets table from the unit DIE's
// DW_AT_str_offsets_base attribute. Split DWARF units do not use this
// attribute, so we assume that there is a contribution to the string
// offsets table starting at offset 0 of the debug_str_offsets.dwo section.
// In both cases we need to determine the format of the contribution,
// which may differ from the unit's format.
uint64_t StringOffsetsContributionBase =
isDWO ? 0 : toSectionOffset(UnitDie.find(DW_AT_str_offsets_base), 0);
if (IndexEntry)
if (const auto *C = IndexEntry->getOffset(DW_SECT_STR_OFFSETS))
StringOffsetsContributionBase += C->Offset;
DWARFDataExtractor DA(Context.getDWARFObj(), StringOffsetSection,
isLittleEndian, 0);
if (isDWO)
StringOffsetsTableContribution =
determineStringOffsetsTableContributionDWO(
DA, StringOffsetsContributionBase);
else if (getVersion() >= 5)
StringOffsetsTableContribution = determineStringOffsetsTableContribution(
DA, StringOffsetsContributionBase);
// Don't fall back to DW_AT_GNU_ranges_base: it should be ignored for
// skeleton CU DIE, so that DWARF users not aware of it are not broken.
}
return DieArray.size();
}
bool DWARFUnit::parseDWO() {
if (isDWO)
return false;
if (DWO.get())
return false;
DWARFDie UnitDie = getUnitDIE();
if (!UnitDie)
return false;
auto DWOFileName = dwarf::toString(UnitDie.find(DW_AT_GNU_dwo_name));
if (!DWOFileName)
return false;
auto CompilationDir = dwarf::toString(UnitDie.find(DW_AT_comp_dir));
SmallString<16> AbsolutePath;
if (sys::path::is_relative(*DWOFileName) && CompilationDir &&
*CompilationDir) {
sys::path::append(AbsolutePath, *CompilationDir);
}
sys::path::append(AbsolutePath, *DWOFileName);
auto DWOId = getDWOId();
if (!DWOId)
return false;
auto DWOContext = Context.getDWOContext(AbsolutePath);
if (!DWOContext)
return false;
DWARFCompileUnit *DWOCU = DWOContext->getDWOCompileUnitForHash(*DWOId);
if (!DWOCU)
return false;
DWO = std::shared_ptr<DWARFCompileUnit>(std::move(DWOContext), DWOCU);
// Share .debug_addr and .debug_ranges section with compile unit in .dwo
DWO->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
auto DWORangesBase = UnitDie.getRangesBaseAttribute();
DWO->setRangesSection(RangeSection, DWORangesBase ? *DWORangesBase : 0);
return true;
}
void DWARFUnit::clearDIEs(bool KeepCUDie) {
if (DieArray.size() > (unsigned)KeepCUDie) {
DieArray.resize((unsigned)KeepCUDie);
DieArray.shrink_to_fit();
}
}
void DWARFUnit::collectAddressRanges(DWARFAddressRangesVector &CURanges) {
DWARFDie UnitDie = getUnitDIE();
if (!UnitDie)
return;
// First, check if unit DIE describes address ranges for the whole unit.
const auto &CUDIERanges = UnitDie.getAddressRanges();
if (!CUDIERanges.empty()) {
CURanges.insert(CURanges.end(), CUDIERanges.begin(), CUDIERanges.end());
return;
}
// This function is usually called if there in no .debug_aranges section
// in order to produce a compile unit level set of address ranges that
// is accurate. If the DIEs weren't parsed, then we don't want all dies for
// all compile units to stay loaded when they weren't needed. So we can end
// up parsing the DWARF and then throwing them all away to keep memory usage
// down.
const bool ClearDIEs = extractDIEsIfNeeded(false) > 1;
getUnitDIE().collectChildrenAddressRanges(CURanges);
// Collect address ranges from DIEs in .dwo if necessary.
bool DWOCreated = parseDWO();
if (DWO)
DWO->collectAddressRanges(CURanges);
if (DWOCreated)
DWO.reset();
// Keep memory down by clearing DIEs if this generate function
// caused them to be parsed.
if (ClearDIEs)
clearDIEs(true);
}
void DWARFUnit::updateAddressDieMap(DWARFDie Die) {
if (Die.isSubroutineDIE()) {
for (const auto &R : Die.getAddressRanges()) {
// Ignore 0-sized ranges.
if (R.LowPC == R.HighPC)
continue;
auto B = AddrDieMap.upper_bound(R.LowPC);
if (B != AddrDieMap.begin() && R.LowPC < (--B)->second.first) {
// The range is a sub-range of existing ranges, we need to split the
// existing range.
if (R.HighPC < B->second.first)
AddrDieMap[R.HighPC] = B->second;
if (R.LowPC > B->first)
AddrDieMap[B->first].first = R.LowPC;
}
AddrDieMap[R.LowPC] = std::make_pair(R.HighPC, Die);
}
}
// Parent DIEs are added to the AddrDieMap prior to the Children DIEs to
// simplify the logic to update AddrDieMap. The child's range will always
// be equal or smaller than the parent's range. With this assumption, when
// adding one range into the map, it will at most split a range into 3
// sub-ranges.
for (DWARFDie Child = Die.getFirstChild(); Child; Child = Child.getSibling())
updateAddressDieMap(Child);
}
DWARFDie DWARFUnit::getSubroutineForAddress(uint64_t Address) {
extractDIEsIfNeeded(false);
if (AddrDieMap.empty())
updateAddressDieMap(getUnitDIE());
auto R = AddrDieMap.upper_bound(Address);
if (R == AddrDieMap.begin())
return DWARFDie();
// upper_bound's previous item contains Address.
--R;
if (Address >= R->second.first)
return DWARFDie();
return R->second.second;
}
void
DWARFUnit::getInlinedChainForAddress(uint64_t Address,
SmallVectorImpl<DWARFDie> &InlinedChain) {
assert(InlinedChain.empty());
// Try to look for subprogram DIEs in the DWO file.
parseDWO();
// First, find the subroutine that contains the given address (the leaf
// of inlined chain).
DWARFDie SubroutineDIE =
(DWO ? DWO.get() : this)->getSubroutineForAddress(Address);
if (!SubroutineDIE)
return;
while (!SubroutineDIE.isSubprogramDIE()) {
if (SubroutineDIE.getTag() == DW_TAG_inlined_subroutine)
InlinedChain.push_back(SubroutineDIE);
SubroutineDIE = SubroutineDIE.getParent();
}
InlinedChain.push_back(SubroutineDIE);
}
const DWARFUnitIndex &llvm::getDWARFUnitIndex(DWARFContext &Context,
DWARFSectionKind Kind) {
if (Kind == DW_SECT_INFO)
return Context.getCUIndex();
assert(Kind == DW_SECT_TYPES);
return Context.getTUIndex();
}
DWARFDie DWARFUnit::getParent(const DWARFDebugInfoEntry *Die) {
if (!Die)
return DWARFDie();
const uint32_t Depth = Die->getDepth();
// Unit DIEs always have a depth of zero and never have parents.
if (Depth == 0)
return DWARFDie();
// Depth of 1 always means parent is the compile/type unit.
if (Depth == 1)
return getUnitDIE();
// Look for previous DIE with a depth that is one less than the Die's depth.
const uint32_t ParentDepth = Depth - 1;
for (uint32_t I = getDIEIndex(Die) - 1; I > 0; --I) {
if (DieArray[I].getDepth() == ParentDepth)
return DWARFDie(this, &DieArray[I]);
}
return DWARFDie();
}
DWARFDie DWARFUnit::getSibling(const DWARFDebugInfoEntry *Die) {
if (!Die)
return DWARFDie();
uint32_t Depth = Die->getDepth();
// Unit DIEs always have a depth of zero and never have siblings.
if (Depth == 0)
return DWARFDie();
// NULL DIEs don't have siblings.
if (Die->getAbbreviationDeclarationPtr() == nullptr)
return DWARFDie();
// Find the next DIE whose depth is the same as the Die's depth.
for (size_t I = getDIEIndex(Die) + 1, EndIdx = DieArray.size(); I < EndIdx;
++I) {
if (DieArray[I].getDepth() == Depth)
return DWARFDie(this, &DieArray[I]);
}
return DWARFDie();
}
DWARFDie DWARFUnit::getFirstChild(const DWARFDebugInfoEntry *Die) {
if (!Die->hasChildren())
return DWARFDie();
// We do not want access out of bounds when parsing corrupted debug data.
size_t I = getDIEIndex(Die) + 1;
if (I >= DieArray.size())
return DWARFDie();
return DWARFDie(this, &DieArray[I]);
}
const DWARFAbbreviationDeclarationSet *DWARFUnit::getAbbreviations() const {
if (!Abbrevs)
Abbrevs = Abbrev->getAbbreviationDeclarationSet(AbbrOffset);
return Abbrevs;
}
Optional<StrOffsetsContributionDescriptor>
StrOffsetsContributionDescriptor::validateContributionSize(
DWARFDataExtractor &DA) {
uint8_t EntrySize = getDwarfOffsetByteSize();
// In order to ensure that we don't read a partial record at the end of
// the section we validate for a multiple of the entry size.
uint64_t ValidationSize = alignTo(Size, EntrySize);
// Guard against overflow.
if (ValidationSize >= Size)
if (DA.isValidOffsetForDataOfSize((uint32_t)Base, ValidationSize))
return *this;
return Optional<StrOffsetsContributionDescriptor>();
}
// Look for a DWARF64-formatted contribution to the string offsets table
// starting at a given offset and record it in a descriptor.
static Optional<StrOffsetsContributionDescriptor>
parseDWARF64StringOffsetsTableHeader(DWARFDataExtractor &DA, uint32_t Offset) {
if (!DA.isValidOffsetForDataOfSize(Offset, 16))
return Optional<StrOffsetsContributionDescriptor>();
if (DA.getU32(&Offset) != 0xffffffff)
return Optional<StrOffsetsContributionDescriptor>();
uint64_t Size = DA.getU64(&Offset);
uint8_t Version = DA.getU16(&Offset);
(void)DA.getU16(&Offset); // padding
return StrOffsetsContributionDescriptor(Offset, Size, Version, DWARF64);
//return Optional<StrOffsetsContributionDescriptor>(Descriptor);
}
// Look for a DWARF32-formatted contribution to the string offsets table
// starting at a given offset and record it in a descriptor.
static Optional<StrOffsetsContributionDescriptor>
parseDWARF32StringOffsetsTableHeader(DWARFDataExtractor &DA, uint32_t Offset) {
if (!DA.isValidOffsetForDataOfSize(Offset, 8))
return Optional<StrOffsetsContributionDescriptor>();
uint32_t ContributionSize = DA.getU32(&Offset);
if (ContributionSize >= 0xfffffff0)
return Optional<StrOffsetsContributionDescriptor>();
uint8_t Version = DA.getU16(&Offset);
(void)DA.getU16(&Offset); // padding
return StrOffsetsContributionDescriptor(Offset, ContributionSize, Version, DWARF32);
//return Optional<StrOffsetsContributionDescriptor>(Descriptor);
}
Optional<StrOffsetsContributionDescriptor>
DWARFUnit::determineStringOffsetsTableContribution(DWARFDataExtractor &DA,
uint64_t Offset) {
Optional<StrOffsetsContributionDescriptor> Descriptor;
// Attempt to find a DWARF64 contribution 16 bytes before the base.
if (Offset >= 16)
Descriptor =
parseDWARF64StringOffsetsTableHeader(DA, (uint32_t)Offset - 16);
// Try to find a DWARF32 contribution 8 bytes before the base.
if (!Descriptor && Offset >= 8)
Descriptor = parseDWARF32StringOffsetsTableHeader(DA, (uint32_t)Offset - 8);
return Descriptor ? Descriptor->validateContributionSize(DA) : Descriptor;
}
Optional<StrOffsetsContributionDescriptor>
DWARFUnit::determineStringOffsetsTableContributionDWO(DWARFDataExtractor &DA,
uint64_t Offset) {
if (getVersion() >= 5) {
// Look for a valid contribution at the given offset.
auto Descriptor =
parseDWARF64StringOffsetsTableHeader(DA, (uint32_t)Offset);
if (!Descriptor)
Descriptor = parseDWARF32StringOffsetsTableHeader(DA, (uint32_t)Offset);
return Descriptor ? Descriptor->validateContributionSize(DA) : Descriptor;
}
// Prior to DWARF v5, we derive the contribution size from the
// index table (in a package file). In a .dwo file it is simply
// the length of the string offsets section.
uint64_t Size = 0;
if (!IndexEntry)
Size = StringOffsetSection.Data.size();
else if (const auto *C = IndexEntry->getOffset(DW_SECT_STR_OFFSETS))
Size = C->Length;
// Return a descriptor with the given offset as base, version 4 and
// DWARF32 format.
//return Optional<StrOffsetsContributionDescriptor>(
//StrOffsetsContributionDescriptor(Offset, Size, 4, DWARF32));
return StrOffsetsContributionDescriptor(Offset, Size, 4, DWARF32);
}
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