Remove old code for updating GDB Index

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Differential Revision: https://phabricator.intern.facebook.com/D58156979

Author: sayhaan

bolt/include/bolt/Rewrite/DWARFRewriter.h

@@ -148,9 +148,6 @@ class DWARFRewriter {
   /// blocks) to be updated.
   void updateDebugAddressRanges();
 
-  /// Rewrite .gdb_index section if present.
-  void updateGdbIndexSection(CUOffsetMap &CUMap, uint32_t NumCUs);
-
   /// DWARFDie contains a pointer to a DIE and hence gets invalidated once the
   /// embedded DIE is destroyed. This wrapper class stores a DIE internally and
   /// could be cast to a DWARFDie that is valid even after the initial DIE is
@@ -192,14 +189,6 @@ class DWARFRewriter {
     DwoRangesBase[DWOId] = RangesBase;
   }
 
-  /// Adds an GDBIndexTUEntry if .gdb_index seciton exists.
-  void addGDBTypeUnitEntry(const GDBIndexTUEntry &&Entry);
-
-  /// Returns all entries needed for Types CU list
-  const GDBIndexTUEntryType &getGDBIndexTUEntryVector() const {
-    return GDBIndexTUEntryVector;
-  }
-
   using OverriddenSectionsMap = std::unordered_map<DWARFSectionKind, StringRef>;
   /// Output .dwo files.
   void writeDWOFiles(DWARFUnit &, const OverriddenSectionsMap &,

bolt/lib/Rewrite/DWARFRewriter.cpp

@@ -184,7 +184,6 @@ namespace bolt {
 /// Emits debug information into .debug_info or .debug_types section.
 class DIEStreamer : public DwarfStreamer {
   DIEBuilder *DIEBldr;
-  DWARFRewriter &Rewriter;
 
 private:
   /// Emit the compilation unit header for \p Unit in the debug_info
@@ -282,8 +281,7 @@ class DIEStreamer : public DwarfStreamer {
               DWARFLinkerBase::OutputFileType OutFileType,
               raw_pwrite_stream &OutFile,
               DWARFLinkerBase::MessageHandlerTy Warning)
-      : DwarfStreamer(OutFileType, OutFile, Warning), DIEBldr(DIEBldr),
-        Rewriter(Rewriter){};
+      : DwarfStreamer(OutFileType, OutFile, Warning), DIEBldr(DIEBldr){};
 
   using DwarfStreamer::emitCompileUnitHeader;
 
@@ -2055,177 +2053,6 @@ void DWARFRewriter::writeDWOFiles(
   TempOut->keep();
 }
 
-void DWARFRewriter::addGDBTypeUnitEntry(const GDBIndexTUEntry &&Entry) {
-  std::lock_guard<std::mutex> Lock(DWARFRewriterMutex);
-  if (!BC.getGdbIndexSection())
-    return;
-  GDBIndexTUEntryVector.emplace_back(Entry);
-}
-
-void DWARFRewriter::updateGdbIndexSection(CUOffsetMap &CUMap, uint32_t NumCUs) {
-  if (!BC.getGdbIndexSection())
-    return;
-
-  // See https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html
-  // for .gdb_index section format.
-
-  StringRef GdbIndexContents = BC.getGdbIndexSection()->getContents();
-
-  const char *Data = GdbIndexContents.data();
-
-  // Parse the header.
-  const uint32_t Version = read32le(Data);
-  if (Version != 7 && Version != 8) {
-    errs() << "BOLT-ERROR: can only process .gdb_index versions 7 and 8\n";
-    exit(1);
-  }
-
-  // Some .gdb_index generators use file offsets while others use section
-  // offsets. Hence we can only rely on offsets relative to each other,
-  // and ignore their absolute values.
-  const uint32_t CUListOffset = read32le(Data + 4);
-  const uint32_t CUTypesOffset = read32le(Data + 8);
-  const uint32_t AddressTableOffset = read32le(Data + 12);
-  const uint32_t SymbolTableOffset = read32le(Data + 16);
-  const uint32_t ConstantPoolOffset = read32le(Data + 20);
-  Data += 24;
-
-  // Map CUs offsets to indices and verify existing index table.
-  std::map<uint32_t, uint32_t> OffsetToIndexMap;
-  const uint32_t CUListSize = CUTypesOffset - CUListOffset;
-  const uint32_t TUListSize = AddressTableOffset - CUTypesOffset;
-  const unsigned NUmCUsEncoded = CUListSize / 16;
-  unsigned MaxDWARFVersion = BC.DwCtx->getMaxVersion();
-  unsigned NumDWARF5TUs =
-      getGDBIndexTUEntryVector().size() - BC.DwCtx->getNumTypeUnits();
-  bool SkipTypeUnits = false;
-  // For DWARF5 Types are in .debug_info.
-  // LLD doesn't generate Types CU List, and in CU list offset
-  // only includes CUs.
-  // GDB 11+ includes only CUs in CU list and generates Types
-  // list.
-  // GDB 9 includes CUs and TUs in CU list and generates TYpes
-  // list. The NumCUs is CUs + TUs, so need to modify the check.
-  // For split-dwarf
-  // GDB-11, DWARF5: TU units from dwo are not included.
-  // GDB-11, DWARF4: TU units from dwo are included.
-  if (MaxDWARFVersion >= 5)
-    SkipTypeUnits = !TUListSize ? true
-                                : ((NUmCUsEncoded + NumDWARF5TUs) ==
-                                   BC.DwCtx->getNumCompileUnits());
-
-  if (!((CUListSize == NumCUs * 16) ||
-        (CUListSize == (NumCUs + NumDWARF5TUs) * 16))) {
-    errs() << "BOLT-ERROR: .gdb_index: CU count mismatch\n";
-    exit(1);
-  }
-  DenseSet<uint64_t> OriginalOffsets;
-  for (unsigned Index = 0, Units = BC.DwCtx->getNumCompileUnits();
-       Index < Units; ++Index) {
-    const DWARFUnit *CU = BC.DwCtx->getUnitAtIndex(Index);
-    if (SkipTypeUnits && CU->isTypeUnit())
-      continue;
-    const uint64_t Offset = read64le(Data);
-    Data += 16;
-    if (CU->getOffset() != Offset) {
-      errs() << "BOLT-ERROR: .gdb_index CU offset mismatch\n";
-      exit(1);
-    }
-
-    OriginalOffsets.insert(Offset);
-    OffsetToIndexMap[Offset] = Index;
-  }
-
-  // Ignore old address table.
-  const uint32_t OldAddressTableSize = SymbolTableOffset - AddressTableOffset;
-  // Move Data to the beginning of symbol table.
-  Data += SymbolTableOffset - CUTypesOffset;
-
-  // Calculate the size of the new address table.
-  uint32_t NewAddressTableSize = 0;
-  for (const auto &CURangesPair : ARangesSectionWriter->getCUAddressRanges()) {
-    const SmallVector<DebugAddressRange, 2> &Ranges = CURangesPair.second;
-    NewAddressTableSize += Ranges.size() * 20;
-  }
-
-  // Difference between old and new table (and section) sizes.
-  // Could be negative.
-  int32_t Delta = NewAddressTableSize - OldAddressTableSize;
-
-  size_t NewGdbIndexSize = GdbIndexContents.size() + Delta;
-
-  // Free'd by ExecutableFileMemoryManager.
-  auto *NewGdbIndexContents = new uint8_t[NewGdbIndexSize];
-  uint8_t *Buffer = NewGdbIndexContents;
-
-  write32le(Buffer, Version);
-  write32le(Buffer + 4, CUListOffset);
-  write32le(Buffer + 8, CUTypesOffset);
-  write32le(Buffer + 12, AddressTableOffset);
-  write32le(Buffer + 16, SymbolTableOffset + Delta);
-  write32le(Buffer + 20, ConstantPoolOffset + Delta);
-  Buffer += 24;
-
-  using MapEntry = std::pair<uint32_t, CUInfo>;
-  std::vector<MapEntry> CUVector(CUMap.begin(), CUMap.end());
-  // Need to sort since we write out all of TUs in .debug_info before CUs.
-  std::sort(CUVector.begin(), CUVector.end(),
-            [](const MapEntry &E1, const MapEntry &E2) -> bool {
-              return E1.second.Offset < E2.second.Offset;
-            });
-  // Writing out CU List <Offset, Size>
-  for (auto &CUInfo : CUVector) {
-    // Skipping TU for DWARF5 when they are not included in CU list.
-    if (!OriginalOffsets.count(CUInfo.first))
-      continue;
-    write64le(Buffer, CUInfo.second.Offset);
-    // Length encoded in CU doesn't contain first 4 bytes that encode length.
-    write64le(Buffer + 8, CUInfo.second.Length + 4);
-    Buffer += 16;
-  }
-
-  // Rewrite TU CU List, since abbrevs can be different.
-  // Entry example:
-  // 0: offset = 0x00000000, type_offset = 0x0000001e, type_signature =
-  // 0x418503b8111e9a7b Spec says " triplet, the first value is the CU offset,
-  // the second value is the type offset in the CU, and the third value is the
-  // type signature" Looking at what is being generated by gdb-add-index. The
-  // first entry is TU offset, second entry is offset from it, and third entry
-  // is the type signature.
-  if (TUListSize)
-    for (const GDBIndexTUEntry &Entry : getGDBIndexTUEntryVector()) {
-      write64le(Buffer, Entry.UnitOffset);
-      write64le(Buffer + 8, Entry.TypeDIERelativeOffset);
-      write64le(Buffer + 16, Entry.TypeHash);
-      Buffer += sizeof(GDBIndexTUEntry);
-    }
-
-  // Generate new address table.
-  for (const std::pair<const uint64_t, DebugAddressRangesVector> &CURangesPair :
-       ARangesSectionWriter->getCUAddressRanges()) {
-    const uint32_t CUIndex = OffsetToIndexMap[CURangesPair.first];
-    const DebugAddressRangesVector &Ranges = CURangesPair.second;
-    for (const DebugAddressRange &Range : Ranges) {
-      write64le(Buffer, Range.LowPC);
-      write64le(Buffer + 8, Range.HighPC);
-      write32le(Buffer + 16, CUIndex);
-      Buffer += 20;
-    }
-  }
-
-  const size_t TrailingSize =
-      GdbIndexContents.data() + GdbIndexContents.size() - Data;
-  assert(Buffer + TrailingSize == NewGdbIndexContents + NewGdbIndexSize &&
-         "size calculation error");
-
-  // Copy over the rest of the original data.
-  memcpy(Buffer, Data, TrailingSize);
-
-  // Register the new section.
-  BC.registerOrUpdateNoteSection(".gdb_index", NewGdbIndexContents,
-                                 NewGdbIndexSize);
-}
-
 std::unique_ptr<DebugBufferVector>
 DWARFRewriter::makeFinalLocListsSection(DWARFVersion Version) {
   auto LocBuffer = std::make_unique<DebugBufferVector>();