llvm/lib/DebugInfo/DWARFUnit.cpp
Alexey Samsonov b58db2293d [DWARF parser] Compress DIEMinimal even further, simplify building DIE tree.
DIE doesn't need to store a pointer to its parent: we can traverse the DIE tree
only with functions getFirstChild() and getSibling(). Parents must be known
only when we construct the tree. Rewrite setDIERelations() procedure in a more
straightforward way, and get rid of lots of now unused DIEMinimal methods.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207563 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 17:12:42 +00:00

362 lines
12 KiB
C++

//===-- DWARFUnit.cpp -----------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "DWARFUnit.h"
#include "DWARFContext.h"
#include "llvm/DebugInfo/DWARFFormValue.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Path.h"
#include <cstdio>
using namespace llvm;
using namespace dwarf;
DWARFUnit::DWARFUnit(const DWARFDebugAbbrev *DA, StringRef IS, StringRef RS,
StringRef SS, StringRef SOS, StringRef AOS,
const RelocAddrMap *M, bool LE)
: Abbrev(DA), InfoSection(IS), RangeSection(RS), StringSection(SS),
StringOffsetSection(SOS), AddrOffsetSection(AOS), RelocMap(M),
isLittleEndian(LE) {
clear();
}
DWARFUnit::~DWARFUnit() {
}
bool DWARFUnit::getAddrOffsetSectionItem(uint32_t Index,
uint64_t &Result) const {
uint32_t Offset = AddrOffsetSectionBase + Index * AddrSize;
if (AddrOffsetSection.size() < Offset + AddrSize)
return false;
DataExtractor DA(AddrOffsetSection, isLittleEndian, AddrSize);
Result = DA.getAddress(&Offset);
return true;
}
bool DWARFUnit::getStringOffsetSectionItem(uint32_t Index,
uint32_t &Result) const {
// FIXME: string offset section entries are 8-byte for DWARF64.
const uint32_t ItemSize = 4;
uint32_t Offset = Index * ItemSize;
if (StringOffsetSection.size() < Offset + ItemSize)
return false;
DataExtractor DA(StringOffsetSection, isLittleEndian, 0);
Result = DA.getU32(&Offset);
return true;
}
bool DWARFUnit::extractImpl(DataExtractor debug_info, uint32_t *offset_ptr) {
Length = debug_info.getU32(offset_ptr);
Version = debug_info.getU16(offset_ptr);
uint64_t AbbrOffset = debug_info.getU32(offset_ptr);
AddrSize = debug_info.getU8(offset_ptr);
bool LengthOK = debug_info.isValidOffset(getNextUnitOffset() - 1);
bool VersionOK = DWARFContext::isSupportedVersion(Version);
bool AddrSizeOK = AddrSize == 4 || AddrSize == 8;
if (!LengthOK || !VersionOK || !AddrSizeOK)
return false;
Abbrevs = Abbrev->getAbbreviationDeclarationSet(AbbrOffset);
if (Abbrevs == nullptr)
return false;
return true;
}
bool DWARFUnit::extract(DataExtractor 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.size() > 0);
DataExtractor RangesData(RangeSection, isLittleEndian, AddrSize);
uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
return RangeList.extract(RangesData, &ActualRangeListOffset);
}
void DWARFUnit::clear() {
Offset = 0;
Length = 0;
Version = 0;
Abbrevs = nullptr;
AddrSize = 0;
BaseAddr = 0;
RangeSectionBase = 0;
AddrOffsetSectionBase = 0;
clearDIEs(false);
DWO.reset();
}
const char *DWARFUnit::getCompilationDir() {
extractDIEsIfNeeded(true);
if (DieArray.empty())
return nullptr;
return DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, nullptr);
}
uint64_t DWARFUnit::getDWOId() {
extractDIEsIfNeeded(true);
const uint64_t FailValue = -1ULL;
if (DieArray.empty())
return FailValue;
return DieArray[0]
.getAttributeValueAsUnsignedConstant(this, DW_AT_GNU_dwo_id, FailValue);
}
void DWARFUnit::setDIERelations() {
if (DieArray.size() <= 1)
return;
std::vector<DWARFDebugInfoEntryMinimal *> ParentChain;
DWARFDebugInfoEntryMinimal *SiblingChain = nullptr;
for (auto &DIE : DieArray) {
if (SiblingChain) {
SiblingChain->setSibling(&DIE);
}
if (const DWARFAbbreviationDeclaration *AbbrDecl =
DIE.getAbbreviationDeclarationPtr()) {
// Normal DIE.
if (AbbrDecl->hasChildren()) {
ParentChain.push_back(&DIE);
SiblingChain = nullptr;
} else {
SiblingChain = &DIE;
}
} else {
// NULL entry terminates the sibling chain.
SiblingChain = ParentChain.back();
ParentChain.pop_back();
}
}
assert(SiblingChain == nullptr || SiblingChain == &DieArray[0]);
assert(ParentChain.empty());
}
void DWARFUnit::extractDIEsToVector(
bool AppendCUDie, bool AppendNonCUDies,
std::vector<DWARFDebugInfoEntryMinimal> &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();
DWARFDebugInfoEntryMinimal DIE;
uint32_t Depth = 0;
bool IsCUDie = true;
while (DIEOffset < NextCUOffset && DIE.extractFast(this, &DIEOffset)) {
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)
fprintf(stderr, "warning: 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.size() > 0) ||
DieArray.size() > 1)
return 0; // Already parsed.
bool HasCUDie = DieArray.size() > 0;
extractDIEsToVector(!HasCUDie, !CUDieOnly, DieArray);
if (DieArray.empty())
return 0;
// If CU DIE was just parsed, copy several attribute values from it.
if (!HasCUDie) {
uint64_t BaseAddr =
DieArray[0].getAttributeValueAsAddress(this, DW_AT_low_pc, -1ULL);
if (BaseAddr == -1ULL)
BaseAddr = DieArray[0].getAttributeValueAsAddress(this, DW_AT_entry_pc, 0);
setBaseAddress(BaseAddr);
AddrOffsetSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
this, DW_AT_GNU_addr_base, 0);
RangeSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
this, DW_AT_GNU_ranges_base, 0);
}
setDIERelations();
return DieArray.size();
}
DWARFUnit::DWOHolder::DWOHolder(object::ObjectFile *DWOFile)
: DWOFile(DWOFile),
DWOContext(cast<DWARFContext>(DIContext::getDWARFContext(DWOFile))),
DWOU(nullptr) {
if (DWOContext->getNumDWOCompileUnits() > 0)
DWOU = DWOContext->getDWOCompileUnitAtIndex(0);
}
bool DWARFUnit::parseDWO() {
if (DWO.get())
return false;
extractDIEsIfNeeded(true);
if (DieArray.empty())
return false;
const char *DWOFileName =
DieArray[0].getAttributeValueAsString(this, DW_AT_GNU_dwo_name, nullptr);
if (!DWOFileName)
return false;
const char *CompilationDir =
DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, nullptr);
SmallString<16> AbsolutePath;
if (sys::path::is_relative(DWOFileName) && CompilationDir != nullptr) {
sys::path::append(AbsolutePath, CompilationDir);
}
sys::path::append(AbsolutePath, DWOFileName);
ErrorOr<object::ObjectFile *> DWOFile =
object::ObjectFile::createObjectFile(AbsolutePath);
if (!DWOFile)
return false;
// Reset DWOHolder.
DWO.reset(new DWOHolder(DWOFile.get()));
DWARFUnit *DWOCU = DWO->getUnit();
// Verify that compile unit in .dwo file is valid.
if (!DWOCU || DWOCU->getDWOId() != getDWOId()) {
DWO.reset();
return false;
}
// Share .debug_addr and .debug_ranges section with compile unit in .dwo
DWOCU->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
DWOCU->setRangesSection(RangeSection, RangeSectionBase);
return true;
}
void DWARFUnit::clearDIEs(bool KeepCUDie) {
if (DieArray.size() > (unsigned)KeepCUDie) {
// std::vectors never get any smaller when resized to a smaller size,
// or when clear() or erase() are called, the size will report that it
// is smaller, but the memory allocated remains intact (call capacity()
// to see this). So we need to create a temporary vector and swap the
// contents which will cause just the internal pointers to be swapped
// so that when temporary vector goes out of scope, it will destroy the
// contents.
std::vector<DWARFDebugInfoEntryMinimal> TmpArray;
DieArray.swap(TmpArray);
// Save at least the compile unit DIE
if (KeepCUDie)
DieArray.push_back(TmpArray.front());
}
}
void DWARFUnit::collectAddressRanges(DWARFAddressRangesVector &CURanges) {
// First, check if CU DIE describes address ranges for the unit.
const auto &CUDIERanges = getCompileUnitDIE()->getAddressRanges(this);
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;
DieArray[0].collectChildrenAddressRanges(this, CURanges);
// Collect address ranges from DIEs in .dwo if necessary.
bool DWOCreated = parseDWO();
if (DWO.get())
DWO->getUnit()->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);
}
const DWARFDebugInfoEntryMinimal *
DWARFUnit::getSubprogramForAddress(uint64_t Address) {
extractDIEsIfNeeded(false);
for (const DWARFDebugInfoEntryMinimal &DIE : DieArray) {
if (DIE.isSubprogramDIE() &&
DIE.addressRangeContainsAddress(this, Address)) {
return &DIE;
}
}
return nullptr;
}
DWARFDebugInfoEntryInlinedChain
DWARFUnit::getInlinedChainForAddress(uint64_t Address) {
// First, find a subprogram that contains the given address (the root
// of inlined chain).
const DWARFUnit *ChainCU = nullptr;
const DWARFDebugInfoEntryMinimal *SubprogramDIE =
getSubprogramForAddress(Address);
if (SubprogramDIE) {
ChainCU = this;
} else {
// Try to look for subprogram DIEs in the DWO file.
parseDWO();
if (DWO.get()) {
SubprogramDIE = DWO->getUnit()->getSubprogramForAddress(Address);
if (SubprogramDIE)
ChainCU = DWO->getUnit();
}
}
// Get inlined chain rooted at this subprogram DIE.
if (!SubprogramDIE)
return DWARFDebugInfoEntryInlinedChain();
return SubprogramDIE->getInlinedChainForAddress(ChainCU, Address);
}