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 "DWARFUnit.h"
11 #include "DWARFContext.h"
12 #include "llvm/DebugInfo/DWARFFormValue.h"
13 #include "llvm/Support/Dwarf.h"
14 #include "llvm/Support/Path.h"
18 using namespace dwarf;
20 void DWARFUnitSectionBase::parse(DWARFContext &C, const DWARFSection &Section) {
21 parseImpl(C, Section, C.getDebugAbbrev(), C.getRangeSection(),
22 C.getStringSection(), StringRef(), C.getAddrSection(),
26 void DWARFUnitSectionBase::parseDWO(DWARFContext &C,
27 const DWARFSection &DWOSection) {
28 parseImpl(C, DWOSection, C.getDebugAbbrevDWO(), C.getRangeDWOSection(),
29 C.getStringDWOSection(), C.getStringOffsetDWOSection(),
30 C.getAddrSection(), C.isLittleEndian());
33 DWARFUnit::DWARFUnit(DWARFContext &DC, const DWARFSection &Section,
34 const DWARFDebugAbbrev *DA, StringRef RS, StringRef SS,
35 StringRef SOS, StringRef AOS, bool LE,
36 const DWARFUnitSectionBase &UnitSection)
37 : Context(DC), InfoSection(Section), Abbrev(DA), RangeSection(RS),
38 StringSection(SS), StringOffsetSection(SOS), AddrOffsetSection(AOS),
39 isLittleEndian(LE), UnitSection(UnitSection) {
43 DWARFUnit::~DWARFUnit() {
46 bool DWARFUnit::getAddrOffsetSectionItem(uint32_t Index,
47 uint64_t &Result) const {
48 uint32_t Offset = AddrOffsetSectionBase + Index * AddrSize;
49 if (AddrOffsetSection.size() < Offset + AddrSize)
51 DataExtractor DA(AddrOffsetSection, isLittleEndian, AddrSize);
52 Result = DA.getAddress(&Offset);
56 bool DWARFUnit::getStringOffsetSectionItem(uint32_t Index,
57 uint32_t &Result) const {
58 // FIXME: string offset section entries are 8-byte for DWARF64.
59 const uint32_t ItemSize = 4;
60 uint32_t Offset = Index * ItemSize;
61 if (StringOffsetSection.size() < Offset + ItemSize)
63 DataExtractor DA(StringOffsetSection, isLittleEndian, 0);
64 Result = DA.getU32(&Offset);
68 bool DWARFUnit::extractImpl(DataExtractor debug_info, uint32_t *offset_ptr) {
69 Length = debug_info.getU32(offset_ptr);
70 Version = debug_info.getU16(offset_ptr);
71 uint64_t AbbrOffset = debug_info.getU32(offset_ptr);
72 AddrSize = debug_info.getU8(offset_ptr);
74 bool LengthOK = debug_info.isValidOffset(getNextUnitOffset() - 1);
75 bool VersionOK = DWARFContext::isSupportedVersion(Version);
76 bool AddrSizeOK = AddrSize == 4 || AddrSize == 8;
78 if (!LengthOK || !VersionOK || !AddrSizeOK)
81 Abbrevs = Abbrev->getAbbreviationDeclarationSet(AbbrOffset);
82 if (Abbrevs == nullptr)
88 bool DWARFUnit::extract(DataExtractor debug_info, uint32_t *offset_ptr) {
93 if (debug_info.isValidOffset(*offset_ptr)) {
94 if (extractImpl(debug_info, offset_ptr))
97 // reset the offset to where we tried to parse from if anything went wrong
104 bool DWARFUnit::extractRangeList(uint32_t RangeListOffset,
105 DWARFDebugRangeList &RangeList) const {
106 // Require that compile unit is extracted.
107 assert(DieArray.size() > 0);
108 DataExtractor RangesData(RangeSection, isLittleEndian, AddrSize);
109 uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
110 return RangeList.extract(RangesData, &ActualRangeListOffset);
113 void DWARFUnit::clear() {
120 RangeSectionBase = 0;
121 AddrOffsetSectionBase = 0;
126 const char *DWARFUnit::getCompilationDir() {
127 extractDIEsIfNeeded(true);
128 if (DieArray.empty())
130 return DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, nullptr);
133 uint64_t DWARFUnit::getDWOId() {
134 extractDIEsIfNeeded(true);
135 const uint64_t FailValue = -1ULL;
136 if (DieArray.empty())
139 .getAttributeValueAsUnsignedConstant(this, DW_AT_GNU_dwo_id, FailValue);
142 void DWARFUnit::setDIERelations() {
143 if (DieArray.size() <= 1)
146 std::vector<DWARFDebugInfoEntryMinimal *> ParentChain;
147 DWARFDebugInfoEntryMinimal *SiblingChain = nullptr;
148 for (auto &DIE : DieArray) {
150 SiblingChain->setSibling(&DIE);
152 if (const DWARFAbbreviationDeclaration *AbbrDecl =
153 DIE.getAbbreviationDeclarationPtr()) {
155 if (AbbrDecl->hasChildren()) {
156 ParentChain.push_back(&DIE);
157 SiblingChain = nullptr;
162 // NULL entry terminates the sibling chain.
163 SiblingChain = ParentChain.back();
164 ParentChain.pop_back();
167 assert(SiblingChain == nullptr || SiblingChain == &DieArray[0]);
168 assert(ParentChain.empty());
171 void DWARFUnit::extractDIEsToVector(
172 bool AppendCUDie, bool AppendNonCUDies,
173 std::vector<DWARFDebugInfoEntryMinimal> &Dies) const {
174 if (!AppendCUDie && !AppendNonCUDies)
177 // Set the offset to that of the first DIE and calculate the start of the
178 // next compilation unit header.
179 uint32_t DIEOffset = Offset + getHeaderSize();
180 uint32_t NextCUOffset = getNextUnitOffset();
181 DWARFDebugInfoEntryMinimal DIE;
185 while (DIEOffset < NextCUOffset && DIE.extractFast(this, &DIEOffset)) {
189 if (!AppendNonCUDies)
191 // The average bytes per DIE entry has been seen to be
192 // around 14-20 so let's pre-reserve the needed memory for
193 // our DIE entries accordingly.
194 Dies.reserve(Dies.size() + getDebugInfoSize() / 14);
200 if (const DWARFAbbreviationDeclaration *AbbrDecl =
201 DIE.getAbbreviationDeclarationPtr()) {
203 if (AbbrDecl->hasChildren())
210 break; // We are done with this compile unit!
214 // Give a little bit of info if we encounter corrupt DWARF (our offset
215 // should always terminate at or before the start of the next compilation
217 if (DIEOffset > NextCUOffset)
218 fprintf(stderr, "warning: DWARF compile unit extends beyond its "
219 "bounds cu 0x%8.8x at 0x%8.8x'\n", getOffset(), DIEOffset);
222 size_t DWARFUnit::extractDIEsIfNeeded(bool CUDieOnly) {
223 if ((CUDieOnly && DieArray.size() > 0) ||
225 return 0; // Already parsed.
227 bool HasCUDie = DieArray.size() > 0;
228 extractDIEsToVector(!HasCUDie, !CUDieOnly, DieArray);
230 if (DieArray.empty())
233 // If CU DIE was just parsed, copy several attribute values from it.
236 DieArray[0].getAttributeValueAsAddress(this, DW_AT_low_pc, -1ULL);
237 if (BaseAddr == -1ULL)
238 BaseAddr = DieArray[0].getAttributeValueAsAddress(this, DW_AT_entry_pc, 0);
239 setBaseAddress(BaseAddr);
240 AddrOffsetSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
241 this, DW_AT_GNU_addr_base, 0);
242 RangeSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
243 this, DW_AT_ranges_base, 0);
244 // Don't fall back to DW_AT_GNU_ranges_base: it should be ignored for
245 // 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 : DWOFile(), DWOContext(), DWOU(nullptr) {
254 auto Obj = object::ObjectFile::createObjectFile(DWOPath);
257 DWOFile = std::move(Obj.get());
259 cast<DWARFContext>(DIContext::getDWARFContext(*DWOFile.getBinary())));
260 if (DWOContext->getNumDWOCompileUnits() > 0)
261 DWOU = DWOContext->getDWOCompileUnitAtIndex(0);
264 bool DWARFUnit::parseDWO() {
267 extractDIEsIfNeeded(true);
268 if (DieArray.empty())
270 const char *DWOFileName =
271 DieArray[0].getAttributeValueAsString(this, DW_AT_GNU_dwo_name, nullptr);
274 const char *CompilationDir =
275 DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, nullptr);
276 SmallString<16> AbsolutePath;
277 if (sys::path::is_relative(DWOFileName) && CompilationDir != nullptr) {
278 sys::path::append(AbsolutePath, CompilationDir);
280 sys::path::append(AbsolutePath, DWOFileName);
281 DWO = llvm::make_unique<DWOHolder>(AbsolutePath);
282 DWARFUnit *DWOCU = DWO->getUnit();
283 // Verify that compile unit in .dwo file is valid.
284 if (!DWOCU || DWOCU->getDWOId() != getDWOId()) {
288 // Share .debug_addr and .debug_ranges section with compile unit in .dwo
289 DWOCU->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
290 uint32_t DWORangesBase = DieArray[0].getRangesBaseAttribute(this, 0);
291 DWOCU->setRangesSection(RangeSection, DWORangesBase);
295 void DWARFUnit::clearDIEs(bool KeepCUDie) {
296 if (DieArray.size() > (unsigned)KeepCUDie) {
297 // std::vectors never get any smaller when resized to a smaller size,
298 // or when clear() or erase() are called, the size will report that it
299 // is smaller, but the memory allocated remains intact (call capacity()
300 // to see this). So we need to create a temporary vector and swap the
301 // contents which will cause just the internal pointers to be swapped
302 // so that when temporary vector goes out of scope, it will destroy the
304 std::vector<DWARFDebugInfoEntryMinimal> TmpArray;
305 DieArray.swap(TmpArray);
306 // Save at least the compile unit DIE
308 DieArray.push_back(TmpArray.front());
312 void DWARFUnit::collectAddressRanges(DWARFAddressRangesVector &CURanges) {
313 // First, check if CU DIE describes address ranges for the unit.
314 const auto &CUDIERanges = getCompileUnitDIE()->getAddressRanges(this);
315 if (!CUDIERanges.empty()) {
316 CURanges.insert(CURanges.end(), CUDIERanges.begin(), CUDIERanges.end());
320 // This function is usually called if there in no .debug_aranges section
321 // in order to produce a compile unit level set of address ranges that
322 // is accurate. If the DIEs weren't parsed, then we don't want all dies for
323 // all compile units to stay loaded when they weren't needed. So we can end
324 // up parsing the DWARF and then throwing them all away to keep memory usage
326 const bool ClearDIEs = extractDIEsIfNeeded(false) > 1;
327 DieArray[0].collectChildrenAddressRanges(this, CURanges);
329 // Collect address ranges from DIEs in .dwo if necessary.
330 bool DWOCreated = parseDWO();
332 DWO->getUnit()->collectAddressRanges(CURanges);
336 // Keep memory down by clearing DIEs if this generate function
337 // caused them to be parsed.
342 const DWARFDebugInfoEntryMinimal *
343 DWARFUnit::getSubprogramForAddress(uint64_t Address) {
344 extractDIEsIfNeeded(false);
345 for (const DWARFDebugInfoEntryMinimal &DIE : DieArray) {
346 if (DIE.isSubprogramDIE() &&
347 DIE.addressRangeContainsAddress(this, Address)) {
354 DWARFDebugInfoEntryInlinedChain
355 DWARFUnit::getInlinedChainForAddress(uint64_t Address) {
356 // First, find a subprogram that contains the given address (the root
357 // of inlined chain).
358 const DWARFUnit *ChainCU = nullptr;
359 const DWARFDebugInfoEntryMinimal *SubprogramDIE =
360 getSubprogramForAddress(Address);
364 // Try to look for subprogram DIEs in the DWO file.
367 SubprogramDIE = DWO->getUnit()->getSubprogramForAddress(Address);
369 ChainCU = DWO->getUnit();
373 // Get inlined chain rooted at this subprogram DIE.
375 return DWARFDebugInfoEntryInlinedChain();
376 return SubprogramDIE->getInlinedChainForAddress(ChainCU, Address);