1 //===-- DWARFUnit.cpp -----------------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/ADT/SmallString.h"
11 #include "llvm/ADT/STLExtras.h"
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
14 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
15 #include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
16 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
17 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
18 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
19 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
20 #include "llvm/Object/ObjectFile.h"
21 #include "llvm/Support/Casting.h"
22 #include "llvm/Support/DataExtractor.h"
23 #include "llvm/Support/Path.h"
32 using namespace dwarf;
34 void DWARFUnitSectionBase::parse(DWARFContext &C, const DWARFSection &Section) {
35 parseImpl(C, Section, C.getDebugAbbrev(), &C.getRangeSection(),
36 C.getStringSection(), StringRef(), C.getAddrSection(),
37 C.getLineSection().Data, C.isLittleEndian(), false);
40 void DWARFUnitSectionBase::parseDWO(DWARFContext &C,
41 const DWARFSection &DWOSection,
42 DWARFUnitIndex *Index) {
43 parseImpl(C, DWOSection, C.getDebugAbbrevDWO(), &C.getRangeDWOSection(),
44 C.getStringDWOSection(), C.getStringOffsetDWOSection(),
45 C.getAddrSection(), C.getLineDWOSection().Data, C.isLittleEndian(),
49 DWARFUnit::DWARFUnit(DWARFContext &DC, const DWARFSection &Section,
50 const DWARFDebugAbbrev *DA, const DWARFSection *RS,
51 StringRef SS, StringRef SOS, StringRef AOS, StringRef LS,
53 const DWARFUnitSectionBase &UnitSection,
54 const DWARFUnitIndex::Entry *IndexEntry)
55 : Context(DC), InfoSection(Section), Abbrev(DA), RangeSection(RS),
56 LineSection(LS), StringSection(SS), StringOffsetSection([&]() {
58 if (const auto *C = IndexEntry->getOffset(DW_SECT_STR_OFFSETS))
59 return SOS.slice(C->Offset, C->Offset + C->Length);
62 AddrOffsetSection(AOS), isLittleEndian(LE), isDWO(IsDWO),
63 UnitSection(UnitSection), IndexEntry(IndexEntry) {
67 DWARFUnit::~DWARFUnit() = default;
69 bool DWARFUnit::getAddrOffsetSectionItem(uint32_t Index,
70 uint64_t &Result) const {
71 uint32_t Offset = AddrOffsetSectionBase + Index * AddrSize;
72 if (AddrOffsetSection.size() < Offset + AddrSize)
74 DataExtractor DA(AddrOffsetSection, isLittleEndian, AddrSize);
75 Result = DA.getAddress(&Offset);
79 bool DWARFUnit::getStringOffsetSectionItem(uint32_t Index,
80 uint32_t &Result) const {
81 // FIXME: string offset section entries are 8-byte for DWARF64.
82 const uint32_t ItemSize = 4;
83 uint32_t Offset = Index * ItemSize;
84 if (StringOffsetSection.size() < Offset + ItemSize)
86 DataExtractor DA(StringOffsetSection, isLittleEndian, 0);
87 Result = DA.getU32(&Offset);
91 bool DWARFUnit::extractImpl(DataExtractor debug_info, uint32_t *offset_ptr) {
92 Length = debug_info.getU32(offset_ptr);
93 Version = debug_info.getU16(offset_ptr);
96 UnitType = debug_info.getU8(offset_ptr);
97 AddrSize = debug_info.getU8(offset_ptr);
98 AbbrOffset = debug_info.getU32(offset_ptr);
100 AbbrOffset = debug_info.getU32(offset_ptr);
101 AddrSize = debug_info.getU8(offset_ptr);
106 auto *UnitContrib = IndexEntry->getOffset();
107 if (!UnitContrib || UnitContrib->Length != (Length + 4))
109 auto *AbbrEntry = IndexEntry->getOffset(DW_SECT_ABBREV);
112 AbbrOffset = AbbrEntry->Offset;
115 bool LengthOK = debug_info.isValidOffset(getNextUnitOffset() - 1);
116 bool VersionOK = DWARFContext::isSupportedVersion(Version);
117 bool AddrSizeOK = AddrSize == 4 || AddrSize == 8;
119 if (!LengthOK || !VersionOK || !AddrSizeOK)
122 Abbrevs = Abbrev->getAbbreviationDeclarationSet(AbbrOffset);
123 return Abbrevs != nullptr;
126 bool DWARFUnit::extract(DataExtractor debug_info, uint32_t *offset_ptr) {
129 Offset = *offset_ptr;
131 if (debug_info.isValidOffset(*offset_ptr)) {
132 if (extractImpl(debug_info, offset_ptr))
135 // reset the offset to where we tried to parse from if anything went wrong
136 *offset_ptr = Offset;
142 bool DWARFUnit::extractRangeList(uint32_t RangeListOffset,
143 DWARFDebugRangeList &RangeList) const {
144 // Require that compile unit is extracted.
145 assert(!DieArray.empty());
146 DataExtractor RangesData(RangeSection->Data, isLittleEndian, AddrSize);
147 uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
148 return RangeList.extract(RangesData, &ActualRangeListOffset,
149 RangeSection->Relocs);
152 void DWARFUnit::clear() {
159 RangeSectionBase = 0;
160 AddrOffsetSectionBase = 0;
165 const char *DWARFUnit::getCompilationDir() {
166 return dwarf::toString(getUnitDIE().find(DW_AT_comp_dir), nullptr);
169 Optional<uint64_t> DWARFUnit::getDWOId() {
170 return toUnsigned(getUnitDIE().find(DW_AT_GNU_dwo_id));
173 void DWARFUnit::extractDIEsToVector(
174 bool AppendCUDie, bool AppendNonCUDies,
175 std::vector<DWARFDebugInfoEntry> &Dies) const {
176 if (!AppendCUDie && !AppendNonCUDies)
179 // Set the offset to that of the first DIE and calculate the start of the
180 // next compilation unit header.
181 uint32_t DIEOffset = Offset + getHeaderSize();
182 uint32_t NextCUOffset = getNextUnitOffset();
183 DWARFDebugInfoEntry DIE;
184 DataExtractor DebugInfoData = getDebugInfoExtractor();
188 while (DIE.extractFast(*this, &DIEOffset, DebugInfoData, NextCUOffset,
193 if (!AppendNonCUDies)
195 // The average bytes per DIE entry has been seen to be
196 // around 14-20 so let's pre-reserve the needed memory for
197 // our DIE entries accordingly.
198 Dies.reserve(Dies.size() + getDebugInfoSize() / 14);
204 if (const DWARFAbbreviationDeclaration *AbbrDecl =
205 DIE.getAbbreviationDeclarationPtr()) {
207 if (AbbrDecl->hasChildren())
214 break; // We are done with this compile unit!
218 // Give a little bit of info if we encounter corrupt DWARF (our offset
219 // should always terminate at or before the start of the next compilation
221 if (DIEOffset > NextCUOffset)
222 fprintf(stderr, "warning: DWARF compile unit extends beyond its "
223 "bounds cu 0x%8.8x at 0x%8.8x'\n", getOffset(), DIEOffset);
226 size_t DWARFUnit::extractDIEsIfNeeded(bool CUDieOnly) {
227 if ((CUDieOnly && !DieArray.empty()) ||
229 return 0; // Already parsed.
231 bool HasCUDie = !DieArray.empty();
232 extractDIEsToVector(!HasCUDie, !CUDieOnly, DieArray);
234 if (DieArray.empty())
237 // If CU DIE was just parsed, copy several attribute values from it.
239 DWARFDie UnitDie = getUnitDIE();
240 auto BaseAddr = toAddress(UnitDie.find({DW_AT_low_pc, DW_AT_entry_pc}));
242 setBaseAddress(*BaseAddr);
243 AddrOffsetSectionBase = toSectionOffset(UnitDie.find(DW_AT_GNU_addr_base), 0);
244 RangeSectionBase = toSectionOffset(UnitDie.find(DW_AT_rnglists_base), 0);
245 // Don't fall back to DW_AT_GNU_ranges_base: it should be ignored for
246 // skeleton CU DIE, so that DWARF users not aware of it are not broken.
249 return DieArray.size();
252 DWARFUnit::DWOHolder::DWOHolder(StringRef DWOPath) {
253 auto Obj = object::ObjectFile::createObjectFile(DWOPath);
255 // TODO: Actually report errors helpfully.
256 consumeError(Obj.takeError());
259 DWOFile = std::move(Obj.get());
261 cast<DWARFContext>(new DWARFContextInMemory(*DWOFile.getBinary())));
262 if (DWOContext->getNumDWOCompileUnits() > 0)
263 DWOU = DWOContext->getDWOCompileUnitAtIndex(0);
266 bool DWARFUnit::parseDWO() {
271 DWARFDie UnitDie = getUnitDIE();
274 auto DWOFileName = dwarf::toString(UnitDie.find(DW_AT_GNU_dwo_name));
277 auto CompilationDir = dwarf::toString(UnitDie.find(DW_AT_comp_dir));
278 SmallString<16> AbsolutePath;
279 if (sys::path::is_relative(*DWOFileName) && CompilationDir &&
281 sys::path::append(AbsolutePath, *CompilationDir);
283 sys::path::append(AbsolutePath, *DWOFileName);
284 DWO = llvm::make_unique<DWOHolder>(AbsolutePath);
285 DWARFUnit *DWOCU = DWO->getUnit();
286 // Verify that compile unit in .dwo file is valid.
287 if (!DWOCU || DWOCU->getDWOId() != getDWOId()) {
291 // Share .debug_addr and .debug_ranges section with compile unit in .dwo
292 DWOCU->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
293 auto DWORangesBase = UnitDie.getRangesBaseAttribute();
294 DWOCU->setRangesSection(RangeSection, DWORangesBase ? *DWORangesBase : 0);
298 void DWARFUnit::clearDIEs(bool KeepCUDie) {
299 if (DieArray.size() > (unsigned)KeepCUDie) {
300 // std::vectors never get any smaller when resized to a smaller size,
301 // or when clear() or erase() are called, the size will report that it
302 // is smaller, but the memory allocated remains intact (call capacity()
303 // to see this). So we need to create a temporary vector and swap the
304 // contents which will cause just the internal pointers to be swapped
305 // so that when temporary vector goes out of scope, it will destroy the
307 std::vector<DWARFDebugInfoEntry> TmpArray;
308 DieArray.swap(TmpArray);
309 // Save at least the compile unit DIE
311 DieArray.push_back(TmpArray.front());
315 void DWARFUnit::collectAddressRanges(DWARFAddressRangesVector &CURanges) {
316 DWARFDie UnitDie = getUnitDIE();
319 // First, check if unit DIE describes address ranges for the whole unit.
320 const auto &CUDIERanges = UnitDie.getAddressRanges();
321 if (!CUDIERanges.empty()) {
322 CURanges.insert(CURanges.end(), CUDIERanges.begin(), CUDIERanges.end());
326 // This function is usually called if there in no .debug_aranges section
327 // in order to produce a compile unit level set of address ranges that
328 // is accurate. If the DIEs weren't parsed, then we don't want all dies for
329 // all compile units to stay loaded when they weren't needed. So we can end
330 // up parsing the DWARF and then throwing them all away to keep memory usage
332 const bool ClearDIEs = extractDIEsIfNeeded(false) > 1;
333 getUnitDIE().collectChildrenAddressRanges(CURanges);
335 // Collect address ranges from DIEs in .dwo if necessary.
336 bool DWOCreated = parseDWO();
338 DWO->getUnit()->collectAddressRanges(CURanges);
342 // Keep memory down by clearing DIEs if this generate function
343 // caused them to be parsed.
348 void DWARFUnit::updateAddressDieMap(DWARFDie Die) {
349 if (Die.isSubroutineDIE()) {
350 for (const auto &R : Die.getAddressRanges()) {
351 // Ignore 0-sized ranges.
352 if (R.LowPC == R.HighPC)
354 auto B = AddrDieMap.upper_bound(R.LowPC);
355 if (B != AddrDieMap.begin() && R.LowPC < (--B)->second.first) {
356 // The range is a sub-range of existing ranges, we need to split the
358 if (R.HighPC < B->second.first)
359 AddrDieMap[R.HighPC] = B->second;
360 if (R.LowPC > B->first)
361 AddrDieMap[B->first].first = R.LowPC;
363 AddrDieMap[R.LowPC] = std::make_pair(R.HighPC, Die);
366 // Parent DIEs are added to the AddrDieMap prior to the Children DIEs to
367 // simplify the logic to update AddrDieMap. The child's range will always
368 // be equal or smaller than the parent's range. With this assumption, when
369 // adding one range into the map, it will at most split a range into 3
371 for (DWARFDie Child = Die.getFirstChild(); Child; Child = Child.getSibling())
372 updateAddressDieMap(Child);
375 DWARFDie DWARFUnit::getSubroutineForAddress(uint64_t Address) {
376 extractDIEsIfNeeded(false);
377 if (AddrDieMap.empty())
378 updateAddressDieMap(getUnitDIE());
379 auto R = AddrDieMap.upper_bound(Address);
380 if (R == AddrDieMap.begin())
382 // upper_bound's previous item contains Address.
384 if (Address >= R->second.first)
386 return R->second.second;
390 DWARFUnit::getInlinedChainForAddress(uint64_t Address,
391 SmallVectorImpl<DWARFDie> &InlinedChain) {
392 assert(InlinedChain.empty());
393 // Try to look for subprogram DIEs in the DWO file.
395 // First, find the subroutine that contains the given address (the leaf
396 // of inlined chain).
397 DWARFDie SubroutineDIE =
398 (DWO ? DWO->getUnit() : this)->getSubroutineForAddress(Address);
400 while (SubroutineDIE) {
401 if (SubroutineDIE.isSubroutineDIE())
402 InlinedChain.push_back(SubroutineDIE);
403 SubroutineDIE = SubroutineDIE.getParent();
407 const DWARFUnitIndex &llvm::getDWARFUnitIndex(DWARFContext &Context,
408 DWARFSectionKind Kind) {
409 if (Kind == DW_SECT_INFO)
410 return Context.getCUIndex();
411 assert(Kind == DW_SECT_TYPES);
412 return Context.getTUIndex();
415 DWARFDie DWARFUnit::getParent(const DWARFDebugInfoEntry *Die) {
418 const uint32_t Depth = Die->getDepth();
419 // Unit DIEs always have a depth of zero and never have parents.
422 // Depth of 1 always means parent is the compile/type unit.
425 // Look for previous DIE with a depth that is one less than the Die's depth.
426 const uint32_t ParentDepth = Depth - 1;
427 for (uint32_t I = getDIEIndex(Die) - 1; I > 0; --I) {
428 if (DieArray[I].getDepth() == ParentDepth)
429 return DWARFDie(this, &DieArray[I]);
434 DWARFDie DWARFUnit::getSibling(const DWARFDebugInfoEntry *Die) {
437 uint32_t Depth = Die->getDepth();
438 // Unit DIEs always have a depth of zero and never have siblings.
441 // NULL DIEs don't have siblings.
442 if (Die->getAbbreviationDeclarationPtr() == nullptr)
445 // Find the next DIE whose depth is the same as the Die's depth.
446 for (size_t I = getDIEIndex(Die) + 1, EndIdx = DieArray.size(); I < EndIdx;
448 if (DieArray[I].getDepth() == Depth)
449 return DWARFDie(this, &DieArray[I]);