Merge pull request #8644 from rastogishubham/DbgStrOffs6

Add zlib compression to the debug_str_offset section

llvm/include/llvm/MCCAS/MCCASObjectV1.h

@@ -588,6 +588,8 @@ class MCCASBuilder {
 
  Expected<SmallVector<DebugStrRef, 0>> createDebugStringRefs();
 
+ std::optional<Expected<DebugStrOffsetsRef>> createDebugStrOffsetsRef();
+
  template <typename SectionTy>
  std::optional<Expected<SectionTy>> createGenericDebugRef(MCSection *Section);
 

llvm/lib/MCCAS/MCCASObjectV1.cpp

@@ -1370,9 +1370,46 @@ static Expected<uint64_t> materializeGenericDebugSection(MCCASReader &Reader,
 Expected<uint64_t>
 DebugStringOffsetsSectionRef::materialize(MCCASReader &Reader,
  raw_ostream *Stream) const {
+ // Start a new section for relocations.
+ Reader.Relocations.emplace_back();
+ SmallVector<char, 0> SectionContents;
+ raw_svector_ostream SectionStream(SectionContents);
+
+ unsigned Size = 0;
  StringRef Remaining = getData();
- return materializeGenericDebugSection<DebugStringOffsetsSectionRef>(
- Reader, Remaining, *this);
+ auto Refs = DebugStringOffsetsSectionRef::decodeReferences(*this, Remaining);
+ if (!Refs)
+ return Refs.takeError();
+
+ for (auto ID : *Refs) {
+ auto FragmentSize = Reader.materializeSection(ID, &SectionStream);
+ if (!FragmentSize)
+ return FragmentSize.takeError();
+ Size += *FragmentSize;
+ }
+
+ if (auto E = decodeRelocations(Reader, Remaining))
+ return std::move(E);
+
+#if LLVM_ENABLE_ZLIB
+ StringRef SectionStringRef = toStringRef(SectionContents);
+ ArrayRef<uint8_t> BufRef = arrayRefFromStringRef(SectionStringRef);
+ assert(BufRef.size() >= 8 &&
+ "Debug String Offset buffer less than 8 bytes in size!");
+ // The zlib decompress function needs to know the uncompressed size of the
+ // buffer. That size is stored as a ULEB at the end of the buffer
+ auto UncompressedSize = decodeULEB128(BufRef.data() + BufRef.size() - 8);
+ BufRef = BufRef.drop_back(8);
+ SmallVector<uint8_t> OutBuff;
+ if (auto E = compression::zlib::decompress(BufRef, OutBuff, UncompressedSize))
+ return E;
+ SectionStringRef = toStringRef(OutBuff);
+ Reader.OS << SectionStringRef;
+ return UncompressedSize;
+#endif
+
+ Reader.OS << SectionContents;
+ return Size;
 }
 
 Expected<uint64_t> DebugLocSectionRef::materialize(MCCASReader &Reader,
@@ -2615,10 +2652,44 @@ MCCASBuilder::createGenericDebugRef(MCSection *Section) {
  return *DebugCASRef;
 }
 
+std::optional<Expected<DebugStrOffsetsRef>>
+MCCASBuilder::createDebugStrOffsetsRef() {
+
+ if (!DwarfSections.StrOffsets ||
+ !DwarfSections.StrOffsets->getFragmentList().size())
+ return std::nullopt;
+
+ auto DebugStrOffsetsData = mergeMCFragmentContents(
+ DwarfSections.StrOffsets->getFragmentList(), false);
+
+ if (!DebugStrOffsetsData)
+ return DebugStrOffsetsData.takeError();
+
+#if LLVM_ENABLE_ZLIB
+ SmallVector<uint8_t> CompressedBuff;
+ compression::zlib::compress(
+ arrayRefFromStringRef(toStringRef(*DebugStrOffsetsData)), CompressedBuff);
+ // Reserve 8 bytes for ULEB to store the size of the uncompressed data.
+ CompressedBuff.append(8, 0);
+ encodeULEB128(DebugStrOffsetsData->size(), CompressedBuff.end() - 8,
+ 8 /*Pad to*/);
+ auto DbgStrOffsetsRef =
+ DebugStrOffsetsRef::create(*this, toStringRef(CompressedBuff));
+ if (!DbgStrOffsetsRef)
+ return DbgStrOffsetsRef.takeError();
+ return *DbgStrOffsetsRef;
+#else
+ auto DbgStrOffsetsRef =
+ DebugStrOffsetsRef::create(*this, toStringRef(*DebugStrOffsetsData));
+ if (!DbgStrOffsetsRef)
+ return DbgStrOffsetsRef.takeError();
+ return *DbgStrOffsetsRef;
+#endif
+}
+
 Error MCCASBuilder::createDebugStrOffsetsSection() {
 
- auto MaybeDebugStringOffsetsRef =
- createGenericDebugRef<DebugStrOffsetsRef>(DwarfSections.StrOffsets);
+ auto MaybeDebugStringOffsetsRef = createDebugStrOffsetsRef();
  if (!MaybeDebugStringOffsetsRef)
  return Error::success();