1 //===- DWARFUnit.h ----------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLVM_DEBUGINFO_DWARF_DWARFUNIT_H
10 #define LLVM_DEBUGINFO_DWARF_DWARFUNIT_H
11 
12 #include "llvm/ADT/DenseSet.h"
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/ADT/StringRef.h"
16 #include "llvm/ADT/iterator_range.h"
17 #include "llvm/BinaryFormat/Dwarf.h"
18 #include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
19 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
20 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
21 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
22 #include "llvm/DebugInfo/DWARF/DWARFLocationExpression.h"
23 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
24 #include "llvm/Support/DataExtractor.h"
25 #include <cassert>
26 #include <cstddef>
27 #include <cstdint>
28 #include <map>
29 #include <memory>
30 #include <set>
31 #include <utility>
32 #include <vector>
33 
34 namespace llvm {
35 
36 class DWARFAbbreviationDeclarationSet;
37 class DWARFContext;
38 class DWARFDebugAbbrev;
39 class DWARFUnit;
40 class DWARFDebugRangeList;
41 class DWARFLocationTable;
42 class DWARFObject;
43 class raw_ostream;
44 struct DIDumpOptions;
45 struct DWARFSection;
46 
47 /// Base class describing the header of any kind of "unit."  Some information
48 /// is specific to certain unit types.  We separate this class out so we can
49 /// parse the header before deciding what specific kind of unit to construct.
50 class DWARFUnitHeader {
51   // Offset within section.
52   uint64_t Offset = 0;
53   // Version, address size, and DWARF format.
54   dwarf::FormParams FormParams;
55   uint64_t Length = 0;
56   uint64_t AbbrOffset = 0;
57 
58   // For DWO units only.
59   const DWARFUnitIndex::Entry *IndexEntry = nullptr;
60 
61   // For type units only.
62   uint64_t TypeHash = 0;
63   uint64_t TypeOffset = 0;
64 
65   // For v5 split or skeleton compile units only.
66   std::optional<uint64_t> DWOId;
67 
68   // Unit type as parsed, or derived from the section kind.
69   uint8_t UnitType = 0;
70 
71   // Size as parsed. uint8_t for compactness.
72   uint8_t Size = 0;
73 
74 public:
75   /// Parse a unit header from \p debug_info starting at \p offset_ptr.
76   /// Note that \p SectionKind is used as a hint to guess the unit type
77   /// for DWARF formats prior to DWARFv5. In DWARFv5 the unit type is
78   /// explicitly defined in the header and the hint is ignored.
79   bool extract(DWARFContext &Context, const DWARFDataExtractor &debug_info,
80                uint64_t *offset_ptr, DWARFSectionKind SectionKind);
81   // For units in DWARF Package File, remember the index entry and update
82   // the abbreviation offset read by extract().
83   bool applyIndexEntry(const DWARFUnitIndex::Entry *Entry);
getOffset()84   uint64_t getOffset() const { return Offset; }
getFormParams()85   const dwarf::FormParams &getFormParams() const { return FormParams; }
getVersion()86   uint16_t getVersion() const { return FormParams.Version; }
getFormat()87   dwarf::DwarfFormat getFormat() const { return FormParams.Format; }
getAddressByteSize()88   uint8_t getAddressByteSize() const { return FormParams.AddrSize; }
getRefAddrByteSize()89   uint8_t getRefAddrByteSize() const { return FormParams.getRefAddrByteSize(); }
getDwarfOffsetByteSize()90   uint8_t getDwarfOffsetByteSize() const {
91     return FormParams.getDwarfOffsetByteSize();
92   }
getLength()93   uint64_t getLength() const { return Length; }
getAbbrOffset()94   uint64_t getAbbrOffset() const { return AbbrOffset; }
getDWOId()95   std::optional<uint64_t> getDWOId() const { return DWOId; }
setDWOId(uint64_t Id)96   void setDWOId(uint64_t Id) {
97     assert((!DWOId || *DWOId == Id) && "setting DWOId to a different value");
98     DWOId = Id;
99   }
getIndexEntry()100   const DWARFUnitIndex::Entry *getIndexEntry() const { return IndexEntry; }
getTypeHash()101   uint64_t getTypeHash() const { return TypeHash; }
getTypeOffset()102   uint64_t getTypeOffset() const { return TypeOffset; }
getUnitType()103   uint8_t getUnitType() const { return UnitType; }
isTypeUnit()104   bool isTypeUnit() const {
105     return UnitType == dwarf::DW_UT_type || UnitType == dwarf::DW_UT_split_type;
106   }
getSize()107   uint8_t getSize() const { return Size; }
getUnitLengthFieldByteSize()108   uint8_t getUnitLengthFieldByteSize() const {
109     return dwarf::getUnitLengthFieldByteSize(FormParams.Format);
110   }
getNextUnitOffset()111   uint64_t getNextUnitOffset() const {
112     return Offset + Length + getUnitLengthFieldByteSize();
113   }
114 };
115 
116 const DWARFUnitIndex &getDWARFUnitIndex(DWARFContext &Context,
117                                         DWARFSectionKind Kind);
118 
119 bool isCompileUnit(const std::unique_ptr<DWARFUnit> &U);
120 
121 /// Describe a collection of units. Intended to hold all units either from
122 /// .debug_info and .debug_types, or from .debug_info.dwo and .debug_types.dwo.
123 class DWARFUnitVector final : public SmallVector<std::unique_ptr<DWARFUnit>, 1> {
124   std::function<std::unique_ptr<DWARFUnit>(uint64_t, DWARFSectionKind,
125                                            const DWARFSection *,
126                                            const DWARFUnitIndex::Entry *)>
127       Parser;
128   int NumInfoUnits = -1;
129 
130 public:
131   using UnitVector = SmallVectorImpl<std::unique_ptr<DWARFUnit>>;
132   using iterator = typename UnitVector::iterator;
133   using iterator_range = llvm::iterator_range<typename UnitVector::iterator>;
134 
135   using compile_unit_range =
136       decltype(make_filter_range(std::declval<iterator_range>(), isCompileUnit));
137 
138   DWARFUnit *getUnitForOffset(uint64_t Offset) const;
139   DWARFUnit *getUnitForIndexEntry(const DWARFUnitIndex::Entry &E);
140 
141   /// Read units from a .debug_info or .debug_types section.  Calls made
142   /// before finishedInfoUnits() are assumed to be for .debug_info sections,
143   /// calls after finishedInfoUnits() are for .debug_types sections.  Caller
144   /// must not mix calls to addUnitsForSection and addUnitsForDWOSection.
145   void addUnitsForSection(DWARFContext &C, const DWARFSection &Section,
146                           DWARFSectionKind SectionKind);
147   /// Read units from a .debug_info.dwo or .debug_types.dwo section.  Calls
148   /// made before finishedInfoUnits() are assumed to be for .debug_info.dwo
149   /// sections, calls after finishedInfoUnits() are for .debug_types.dwo
150   /// sections.  Caller must not mix calls to addUnitsForSection and
151   /// addUnitsForDWOSection.
152   void addUnitsForDWOSection(DWARFContext &C, const DWARFSection &DWOSection,
153                              DWARFSectionKind SectionKind, bool Lazy = false);
154 
155   /// Add an existing DWARFUnit to this UnitVector. This is used by the DWARF
156   /// verifier to process unit separately.
157   DWARFUnit *addUnit(std::unique_ptr<DWARFUnit> Unit);
158 
159   /// Returns number of all units held by this instance.
getNumUnits()160   unsigned getNumUnits() const { return size(); }
161   /// Returns number of units from all .debug_info[.dwo] sections.
getNumInfoUnits()162   unsigned getNumInfoUnits() const {
163     return NumInfoUnits == -1 ? size() : NumInfoUnits;
164   }
165   /// Returns number of units from all .debug_types[.dwo] sections.
getNumTypesUnits()166   unsigned getNumTypesUnits() const { return size() - NumInfoUnits; }
167   /// Indicate that parsing .debug_info[.dwo] is done, and remaining units
168   /// will be from .debug_types[.dwo].
finishedInfoUnits()169   void finishedInfoUnits() { NumInfoUnits = size(); }
170 
171 private:
172   void addUnitsImpl(DWARFContext &Context, const DWARFObject &Obj,
173                     const DWARFSection &Section, const DWARFDebugAbbrev *DA,
174                     const DWARFSection *RS, const DWARFSection *LocSection,
175                     StringRef SS, const DWARFSection &SOS,
176                     const DWARFSection *AOS, const DWARFSection &LS, bool LE,
177                     bool IsDWO, bool Lazy, DWARFSectionKind SectionKind);
178 };
179 
180 /// Represents base address of the CU.
181 /// Represents a unit's contribution to the string offsets table.
182 struct StrOffsetsContributionDescriptor {
183   uint64_t Base = 0;
184   /// The contribution size not including the header.
185   uint64_t Size = 0;
186   /// Format and version.
187   dwarf::FormParams FormParams = {0, 0, dwarf::DwarfFormat::DWARF32};
188 
StrOffsetsContributionDescriptorStrOffsetsContributionDescriptor189   StrOffsetsContributionDescriptor(uint64_t Base, uint64_t Size,
190                                    uint8_t Version, dwarf::DwarfFormat Format)
191       : Base(Base), Size(Size), FormParams({Version, 0, Format}) {}
192   StrOffsetsContributionDescriptor() = default;
193 
getVersionStrOffsetsContributionDescriptor194   uint8_t getVersion() const { return FormParams.Version; }
getFormatStrOffsetsContributionDescriptor195   dwarf::DwarfFormat getFormat() const { return FormParams.Format; }
getDwarfOffsetByteSizeStrOffsetsContributionDescriptor196   uint8_t getDwarfOffsetByteSize() const {
197     return FormParams.getDwarfOffsetByteSize();
198   }
199   /// Determine whether a contribution to the string offsets table is
200   /// consistent with the relevant section size and that its length is
201   /// a multiple of the size of one of its entries.
202   Expected<StrOffsetsContributionDescriptor>
203   validateContributionSize(DWARFDataExtractor &DA);
204 };
205 
206 class DWARFUnit {
207   DWARFContext &Context;
208   /// Section containing this DWARFUnit.
209   const DWARFSection &InfoSection;
210 
211   DWARFUnitHeader Header;
212   const DWARFDebugAbbrev *Abbrev;
213   const DWARFSection *RangeSection;
214   uint64_t RangeSectionBase;
215   uint64_t LocSectionBase;
216 
217   /// Location table of this unit.
218   std::unique_ptr<DWARFLocationTable> LocTable;
219 
220   const DWARFSection &LineSection;
221   StringRef StringSection;
222   const DWARFSection &StringOffsetSection;
223   const DWARFSection *AddrOffsetSection;
224   DWARFUnit *SU;
225   std::optional<uint64_t> AddrOffsetSectionBase;
226   bool IsLittleEndian;
227   bool IsDWO;
228   const DWARFUnitVector &UnitVector;
229 
230   /// Start, length, and DWARF format of the unit's contribution to the string
231   /// offsets table (DWARF v5).
232   std::optional<StrOffsetsContributionDescriptor>
233       StringOffsetsTableContribution;
234 
235   mutable const DWARFAbbreviationDeclarationSet *Abbrevs;
236   std::optional<object::SectionedAddress> BaseAddr;
237   /// The compile unit debug information entry items.
238   std::vector<DWARFDebugInfoEntry> DieArray;
239 
240   /// Map from range's start address to end address and corresponding DIE.
241   /// IntervalMap does not support range removal, as a result, we use the
242   /// std::map::upper_bound for address range lookup.
243   std::map<uint64_t, std::pair<uint64_t, DWARFDie>> AddrDieMap;
244 
245   /// Map from the location (interpreted DW_AT_location) of a DW_TAG_variable,
246   /// to the end address and the corresponding DIE.
247   std::map<uint64_t, std::pair<uint64_t, DWARFDie>> VariableDieMap;
248   DenseSet<uint64_t> RootsParsedForVariables;
249 
250   using die_iterator_range =
251       iterator_range<std::vector<DWARFDebugInfoEntry>::iterator>;
252 
253   std::shared_ptr<DWARFUnit> DWO;
254 
255 protected:
256   /// Return the index of a \p Die entry inside the unit's DIE vector.
257   ///
258   /// It is illegal to call this method with a DIE that hasn't be
259   /// created by this unit. In other word, it's illegal to call this
260   /// method on a DIE that isn't accessible by following
261   /// children/sibling links starting from this unit's getUnitDIE().
getDIEIndex(const DWARFDebugInfoEntry * Die)262   uint32_t getDIEIndex(const DWARFDebugInfoEntry *Die) const {
263     auto First = DieArray.data();
264     assert(Die >= First && Die < First + DieArray.size());
265     return Die - First;
266   }
267 
268   /// Return DWARFDebugInfoEntry for the specified index \p Index.
getDebugInfoEntry(unsigned Index)269   const DWARFDebugInfoEntry *getDebugInfoEntry(unsigned Index) const {
270     assert(Index < DieArray.size());
271     return &DieArray[Index];
272   }
273 
274   const DWARFDebugInfoEntry *
275   getParentEntry(const DWARFDebugInfoEntry *Die) const;
276   const DWARFDebugInfoEntry *
277   getSiblingEntry(const DWARFDebugInfoEntry *Die) const;
278   const DWARFDebugInfoEntry *
279   getPreviousSiblingEntry(const DWARFDebugInfoEntry *Die) const;
280   const DWARFDebugInfoEntry *
281   getFirstChildEntry(const DWARFDebugInfoEntry *Die) const;
282   const DWARFDebugInfoEntry *
283   getLastChildEntry(const DWARFDebugInfoEntry *Die) const;
284 
getHeader()285   const DWARFUnitHeader &getHeader() const { return Header; }
286 
287   /// Find the unit's contribution to the string offsets table and determine its
288   /// length and form. The given offset is expected to be derived from the unit
289   /// DIE's DW_AT_str_offsets_base attribute.
290   Expected<std::optional<StrOffsetsContributionDescriptor>>
291   determineStringOffsetsTableContribution(DWARFDataExtractor &DA);
292 
293   /// Find the unit's contribution to the string offsets table and determine its
294   /// length and form. The given offset is expected to be 0 in a dwo file or,
295   /// in a dwp file, the start of the unit's contribution to the string offsets
296   /// table section (as determined by the index table).
297   Expected<std::optional<StrOffsetsContributionDescriptor>>
298   determineStringOffsetsTableContributionDWO(DWARFDataExtractor &DA);
299 
300 public:
301   DWARFUnit(DWARFContext &Context, const DWARFSection &Section,
302             const DWARFUnitHeader &Header, const DWARFDebugAbbrev *DA,
303             const DWARFSection *RS, const DWARFSection *LocSection,
304             StringRef SS, const DWARFSection &SOS, const DWARFSection *AOS,
305             const DWARFSection &LS, bool LE, bool IsDWO,
306             const DWARFUnitVector &UnitVector);
307 
308   virtual ~DWARFUnit();
309 
isLittleEndian()310   bool isLittleEndian() const { return IsLittleEndian; }
isDWOUnit()311   bool isDWOUnit() const { return IsDWO; }
getContext()312   DWARFContext& getContext() const { return Context; }
getInfoSection()313   const DWARFSection &getInfoSection() const { return InfoSection; }
getOffset()314   uint64_t getOffset() const { return Header.getOffset(); }
getFormParams()315   const dwarf::FormParams &getFormParams() const {
316     return Header.getFormParams();
317   }
getVersion()318   uint16_t getVersion() const { return Header.getVersion(); }
getAddressByteSize()319   uint8_t getAddressByteSize() const { return Header.getAddressByteSize(); }
getRefAddrByteSize()320   uint8_t getRefAddrByteSize() const { return Header.getRefAddrByteSize(); }
getDwarfOffsetByteSize()321   uint8_t getDwarfOffsetByteSize() const {
322     return Header.getDwarfOffsetByteSize();
323   }
324   /// Size in bytes of the parsed unit header.
getHeaderSize()325   uint32_t getHeaderSize() const { return Header.getSize(); }
getLength()326   uint64_t getLength() const { return Header.getLength(); }
getFormat()327   dwarf::DwarfFormat getFormat() const { return Header.getFormat(); }
getUnitType()328   uint8_t getUnitType() const { return Header.getUnitType(); }
isTypeUnit()329   bool isTypeUnit() const { return Header.isTypeUnit(); }
getAbbrOffset()330   uint64_t getAbbrOffset() const { return Header.getAbbrOffset(); }
getNextUnitOffset()331   uint64_t getNextUnitOffset() const { return Header.getNextUnitOffset(); }
getLineSection()332   const DWARFSection &getLineSection() const { return LineSection; }
getStringSection()333   StringRef getStringSection() const { return StringSection; }
getStringOffsetSection()334   const DWARFSection &getStringOffsetSection() const {
335     return StringOffsetSection;
336   }
337 
setSkeletonUnit(DWARFUnit * SU)338   void setSkeletonUnit(DWARFUnit *SU) { this->SU = SU; }
339   // Returns itself if not using Split DWARF, or if the unit is a skeleton unit
340   // - otherwise returns the split full unit's corresponding skeleton, if
341   // available.
getLinkedUnit()342   DWARFUnit *getLinkedUnit() { return IsDWO ? SU : this; }
343 
setAddrOffsetSection(const DWARFSection * AOS,uint64_t Base)344   void setAddrOffsetSection(const DWARFSection *AOS, uint64_t Base) {
345     AddrOffsetSection = AOS;
346     AddrOffsetSectionBase = Base;
347   }
348 
getAddrOffsetSectionBase()349   std::optional<uint64_t> getAddrOffsetSectionBase() const {
350     return AddrOffsetSectionBase;
351   }
352 
353   /// Recursively update address to Die map.
354   void updateAddressDieMap(DWARFDie Die);
355 
356   /// Recursively update address to variable Die map.
357   void updateVariableDieMap(DWARFDie Die);
358 
setRangesSection(const DWARFSection * RS,uint64_t Base)359   void setRangesSection(const DWARFSection *RS, uint64_t Base) {
360     RangeSection = RS;
361     RangeSectionBase = Base;
362   }
363 
getLocSectionBase()364   uint64_t getLocSectionBase() const {
365     return LocSectionBase;
366   }
367 
368   std::optional<object::SectionedAddress>
369   getAddrOffsetSectionItem(uint32_t Index) const;
370   Expected<uint64_t> getStringOffsetSectionItem(uint32_t Index) const;
371 
372   DWARFDataExtractor getDebugInfoExtractor() const;
373 
getStringExtractor()374   DataExtractor getStringExtractor() const {
375     return DataExtractor(StringSection, false, 0);
376   }
377 
getLocationTable()378   const DWARFLocationTable &getLocationTable() { return *LocTable; }
379 
380   /// Extract the range list referenced by this compile unit from the
381   /// .debug_ranges section. If the extraction is unsuccessful, an error
382   /// is returned. Successful extraction requires that the compile unit
383   /// has already been extracted.
384   Error extractRangeList(uint64_t RangeListOffset,
385                          DWARFDebugRangeList &RangeList) const;
386   void clear();
387 
388   const std::optional<StrOffsetsContributionDescriptor> &
getStringOffsetsTableContribution()389   getStringOffsetsTableContribution() const {
390     return StringOffsetsTableContribution;
391   }
392 
getDwarfStringOffsetsByteSize()393   uint8_t getDwarfStringOffsetsByteSize() const {
394     assert(StringOffsetsTableContribution);
395     return StringOffsetsTableContribution->getDwarfOffsetByteSize();
396   }
397 
getStringOffsetsBase()398   uint64_t getStringOffsetsBase() const {
399     assert(StringOffsetsTableContribution);
400     return StringOffsetsTableContribution->Base;
401   }
402 
getAbbreviationsOffset()403   uint64_t getAbbreviationsOffset() const { return Header.getAbbrOffset(); }
404 
405   const DWARFAbbreviationDeclarationSet *getAbbreviations() const;
406 
isMatchingUnitTypeAndTag(uint8_t UnitType,dwarf::Tag Tag)407   static bool isMatchingUnitTypeAndTag(uint8_t UnitType, dwarf::Tag Tag) {
408     switch (UnitType) {
409     case dwarf::DW_UT_compile:
410       return Tag == dwarf::DW_TAG_compile_unit;
411     case dwarf::DW_UT_type:
412       return Tag == dwarf::DW_TAG_type_unit;
413     case dwarf::DW_UT_partial:
414       return Tag == dwarf::DW_TAG_partial_unit;
415     case dwarf::DW_UT_skeleton:
416       return Tag == dwarf::DW_TAG_skeleton_unit;
417     case dwarf::DW_UT_split_compile:
418     case dwarf::DW_UT_split_type:
419       return dwarf::isUnitType(Tag);
420     }
421     return false;
422   }
423 
424   std::optional<object::SectionedAddress> getBaseAddress();
425 
426   DWARFDie getUnitDIE(bool ExtractUnitDIEOnly = true) {
427     extractDIEsIfNeeded(ExtractUnitDIEOnly);
428     if (DieArray.empty())
429       return DWARFDie();
430     return DWARFDie(this, &DieArray[0]);
431   }
432 
433   DWARFDie getNonSkeletonUnitDIE(bool ExtractUnitDIEOnly = true,
434                                  StringRef DWOAlternativeLocation = {}) {
435     parseDWO(DWOAlternativeLocation);
436     return DWO ? DWO->getUnitDIE(ExtractUnitDIEOnly)
437                : getUnitDIE(ExtractUnitDIEOnly);
438   }
439 
440   const char *getCompilationDir();
getDWOId()441   std::optional<uint64_t> getDWOId() {
442     extractDIEsIfNeeded(/*CUDieOnly*/ true);
443     return getHeader().getDWOId();
444   }
setDWOId(uint64_t NewID)445   void setDWOId(uint64_t NewID) { Header.setDWOId(NewID); }
446 
447   /// Return a vector of address ranges resulting from a (possibly encoded)
448   /// range list starting at a given offset in the appropriate ranges section.
449   Expected<DWARFAddressRangesVector> findRnglistFromOffset(uint64_t Offset);
450 
451   /// Return a vector of address ranges retrieved from an encoded range
452   /// list whose offset is found via a table lookup given an index (DWARF v5
453   /// and later).
454   Expected<DWARFAddressRangesVector> findRnglistFromIndex(uint32_t Index);
455 
456   /// Return a rangelist's offset based on an index. The index designates
457   /// an entry in the rangelist table's offset array and is supplied by
458   /// DW_FORM_rnglistx.
459   std::optional<uint64_t> getRnglistOffset(uint32_t Index);
460 
461   std::optional<uint64_t> getLoclistOffset(uint32_t Index);
462 
463   Expected<DWARFAddressRangesVector> collectAddressRanges();
464 
465   Expected<DWARFLocationExpressionsVector>
466   findLoclistFromOffset(uint64_t Offset);
467 
468   /// Returns subprogram DIE with address range encompassing the provided
469   /// address. The pointer is alive as long as parsed compile unit DIEs are not
470   /// cleared.
471   DWARFDie getSubroutineForAddress(uint64_t Address);
472 
473   /// Returns variable DIE for the address provided. The pointer is alive as
474   /// long as parsed compile unit DIEs are not cleared.
475   DWARFDie getVariableForAddress(uint64_t Address);
476 
477   /// getInlinedChainForAddress - fetches inlined chain for a given address.
478   /// Returns empty chain if there is no subprogram containing address. The
479   /// chain is valid as long as parsed compile unit DIEs are not cleared.
480   void getInlinedChainForAddress(uint64_t Address,
481                                  SmallVectorImpl<DWARFDie> &InlinedChain);
482 
483   /// Return the DWARFUnitVector containing this unit.
getUnitVector()484   const DWARFUnitVector &getUnitVector() const { return UnitVector; }
485 
486   /// Returns the number of DIEs in the unit. Parses the unit
487   /// if necessary.
getNumDIEs()488   unsigned getNumDIEs() {
489     extractDIEsIfNeeded(false);
490     return DieArray.size();
491   }
492 
493   /// Return the index of a DIE inside the unit's DIE vector.
494   ///
495   /// It is illegal to call this method with a DIE that hasn't be
496   /// created by this unit. In other word, it's illegal to call this
497   /// method on a DIE that isn't accessible by following
498   /// children/sibling links starting from this unit's getUnitDIE().
getDIEIndex(const DWARFDie & D)499   uint32_t getDIEIndex(const DWARFDie &D) const {
500     return getDIEIndex(D.getDebugInfoEntry());
501   }
502 
503   /// Return the DIE object at the given index \p Index.
getDIEAtIndex(unsigned Index)504   DWARFDie getDIEAtIndex(unsigned Index) {
505     return DWARFDie(this, getDebugInfoEntry(Index));
506   }
507 
508   DWARFDie getParent(const DWARFDebugInfoEntry *Die);
509   DWARFDie getSibling(const DWARFDebugInfoEntry *Die);
510   DWARFDie getPreviousSibling(const DWARFDebugInfoEntry *Die);
511   DWARFDie getFirstChild(const DWARFDebugInfoEntry *Die);
512   DWARFDie getLastChild(const DWARFDebugInfoEntry *Die);
513 
514   /// Return the DIE object for a given offset \p Offset inside the
515   /// unit's DIE vector.
getDIEForOffset(uint64_t Offset)516   DWARFDie getDIEForOffset(uint64_t Offset) {
517     if (std::optional<uint32_t> DieIdx = getDIEIndexForOffset(Offset))
518       return DWARFDie(this, &DieArray[*DieIdx]);
519 
520     return DWARFDie();
521   }
522 
523   /// Return the DIE index for a given offset \p Offset inside the
524   /// unit's DIE vector.
getDIEIndexForOffset(uint64_t Offset)525   std::optional<uint32_t> getDIEIndexForOffset(uint64_t Offset) {
526     extractDIEsIfNeeded(false);
527     auto It =
528         llvm::partition_point(DieArray, [=](const DWARFDebugInfoEntry &DIE) {
529           return DIE.getOffset() < Offset;
530         });
531     if (It != DieArray.end() && It->getOffset() == Offset)
532       return It - DieArray.begin();
533     return std::nullopt;
534   }
535 
getLineTableOffset()536   uint32_t getLineTableOffset() const {
537     if (auto IndexEntry = Header.getIndexEntry())
538       if (const auto *Contrib = IndexEntry->getContribution(DW_SECT_LINE))
539         return Contrib->getOffset32();
540     return 0;
541   }
542 
dies()543   die_iterator_range dies() {
544     extractDIEsIfNeeded(false);
545     return die_iterator_range(DieArray.begin(), DieArray.end());
546   }
547 
548   virtual void dump(raw_ostream &OS, DIDumpOptions DumpOpts) = 0;
549 
550   Error tryExtractDIEsIfNeeded(bool CUDieOnly);
551 
552 private:
553   /// Size in bytes of the .debug_info data associated with this compile unit.
getDebugInfoSize()554   size_t getDebugInfoSize() const {
555     return Header.getLength() + Header.getUnitLengthFieldByteSize() -
556            getHeaderSize();
557   }
558 
559   /// extractDIEsIfNeeded - Parses a compile unit and indexes its DIEs if it
560   /// hasn't already been done
561   void extractDIEsIfNeeded(bool CUDieOnly);
562 
563   /// extractDIEsToVector - Appends all parsed DIEs to a vector.
564   void extractDIEsToVector(bool AppendCUDie, bool AppendNonCUDIEs,
565                            std::vector<DWARFDebugInfoEntry> &DIEs) const;
566 
567   /// clearDIEs - Clear parsed DIEs to keep memory usage low.
568   void clearDIEs(bool KeepCUDie);
569 
570   /// parseDWO - Parses .dwo file for current compile unit. Returns true if
571   /// it was actually constructed.
572   /// The \p AlternativeLocation specifies an alternative location to get
573   /// the DWARF context for the DWO object; this is the case when it has
574   /// been moved from its original location.
575   bool parseDWO(StringRef AlternativeLocation = {});
576 };
577 
isCompileUnit(const std::unique_ptr<DWARFUnit> & U)578 inline bool isCompileUnit(const std::unique_ptr<DWARFUnit> &U) {
579   return !U->isTypeUnit();
580 }
581 
582 } // end namespace llvm
583 
584 #endif // LLVM_DEBUGINFO_DWARF_DWARFUNIT_H
585