[llvm-dwp] Add SHF_COMPRESSED support and remove .zdebug support

[MaskRay]

Summary

clang 14 removed -gz=zlib-gnu and ld.lld/llvm-objcopy removed .zdebug support
recently. llvm-dwp currently doesn't support SHF_COMPRESSED. Add support and
remove .zdebug support.

Simplify llvm::object::Decompressor which has no .zdebug user now.

While here, add tests for ELF32LE, ELF32BE, and ELF64BE.

[dblaikie]

Looks OK, thanks!

llvm/lib/DWP/DWP.cpp

282–287

This should probably be in a separate patch with test coverage (though generally I don't think adding functionality/doing work on llvm-dwp is really worth it - it probably needs to be thrown out & start again to make it sufficiently efficient in terms of memory usage, etc - though with the WebAssembly (so the costly abstractions are now load-bearing to support WebAssembly) support added & lld's non-generality (so doesn't have sufficient abstractions to make it trivial to implement over different formats), it's not clear what the foundation of such a new implementation would be, whether the generality can be maintained while achieving the desired performance, etc).

A FIXME could document what's entailed in adding the endian/size functionality here.

[MaskRay]

llvm/lib/DWP/DWP.cpp

282–287

Will add a TODO that this is untested (some binary utilities use TODO to indicate no test coverage as well).

Thanks for the insight that llvm-dwp probably should be re-implemented. I haven't followed the development...

(@ckissane)

[dblaikie]

llvm/lib/DWP/DWP.cpp

282–287

I'd prefer it not be checked in untested.

[dblaikie]

llvm/lib/DWP/DWP.cpp

282–287

Sorry, should've provided more context: There are some cases where I think untested functionality is warranted, when testing is particularly difficult & manual testing is done as a stop-gap.

In this case I don't think it's much of a value-add, the functionality isn't used much & sort of a paradox of "if it's used just enough to be useful/but then untested, that's especially unfortunate".

If there's concern about this misbehaving, I'd be open to an assertion with a FIXME about how to support other things if someone comes across the assertion.

[MaskRay]

Test {32,64} x {LSB,MSB}

[MaskRay]

llvm/lib/DWP/DWP.cpp

282–287

It's actually not too difficult to test all 4 ELF types. Just added the tests.

[dblaikie]

Sounds good :)

llvm/test/tools/llvm-dwp/X86/compress.test

35–36

Might be more readable to not use a default (=64) so the RUN lines are explicit about 32/64 in the same way they are explicit about LSB/MSB?

[MaskRay]

llvm/test/tools/llvm-dwp/X86/compress.test

35–36

Thanks for the suggestion. Will push with the change.

[dyung]

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

[MaskRay]

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

[dblaikie]

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

Please don't remove test coverage like this - this test covers the error path here: https://github.com/llvm/llvm-project/blob/33aa374e597260dae739bb949892cff31ae31eb9/llvm/lib/DWP/DWP.cpp#L288

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

[MaskRay]

In D129728#3653769, @dblaikie wrote:

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

Please don't remove test coverage like this - this test covers the error path here: https://github.com/llvm/llvm-project/blob/33aa374e597260dae739bb949892cff31ae31eb9/llvm/lib/DWP/DWP.cpp#L288

It's a fast way to get bots green. It takes time to construct a test. In lld/test/ELF I added tests testing UNSUPPORTED: zlib.

[dblaikie]

In D129728#3653775, @MaskRay wrote:

In D129728#3653769, @dblaikie wrote:

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

Please don't remove test coverage like this - this test covers the error path here: https://github.com/llvm/llvm-project/blob/33aa374e597260dae739bb949892cff31ae31eb9/llvm/lib/DWP/DWP.cpp#L288

It's a fast way to get bots green. It takes time to construct a test.

The usual way to do that if this would take to long is to revert the causal patch while addressing the regression - not lower test coverage permanently.

In lld/test/ELF I added tests testing UNSUPPORTED: zlib.

Sure - that doesn't test the DWP error handling codepath linked above, though.

[MaskRay]

In D129728#3653781, @dblaikie wrote:

In D129728#3653775, @MaskRay wrote:

In D129728#3653769, @dblaikie wrote:

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

Please don't remove test coverage like this - this test covers the error path here: https://github.com/llvm/llvm-project/blob/33aa374e597260dae739bb949892cff31ae31eb9/llvm/lib/DWP/DWP.cpp#L288

It's a fast way to get bots green. It takes time to construct a test.

The usual way to do that if this would take to long is to revert the causal patch while addressing the regression - not lower test coverage permanently.

The file will need to be re-added anyway to avoid the precanned binary. Adding a test in one minute, I am not sure it's useful to revert this current patch.

In lld/test/ELF I added tests testing UNSUPPORTED: zlib.

Sure - that doesn't test the DWP error handling codepath linked above, though.

This sentence just wanted to say I know that a test is needed.

[dblaikie]

In D129728#3653818, @MaskRay wrote:

In D129728#3653781, @dblaikie wrote:

In D129728#3653775, @MaskRay wrote:

In D129728#3653769, @dblaikie wrote:

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

Please don't remove test coverage like this - this test covers the error path here: https://github.com/llvm/llvm-project/blob/33aa374e597260dae739bb949892cff31ae31eb9/llvm/lib/DWP/DWP.cpp#L288

It's a fast way to get bots green. It takes time to construct a test.

The usual way to do that if this would take to long is to revert the causal patch while addressing the regression - not lower test coverage permanently.

The file will need to be re-added anyway to avoid the precanned binary. Adding a test in one minute, I am not sure it's useful to revert this current patch.

Ah, OK - thanks! Nah, I don't mind fixing forward here, though I think in the future it'd be simpler/clearer if the patch were reverted and recommitted correctly rather than temporarily removing testing like this.

[MaskRay]

In D129728#3653821, @dblaikie wrote:

In D129728#3653818, @MaskRay wrote:

In D129728#3653781, @dblaikie wrote:

In D129728#3653775, @MaskRay wrote:

In D129728#3653769, @dblaikie wrote:

In D129728#3653748, @MaskRay wrote:

In D129728#3653746, @dyung wrote:

Your change is causing the test 'LLVM :: tools/llvm-dwp/X86/nocompress.test' to fail due to one of the expected input files being deleted by your change. Perhaps you need to delete or fixup this test as well?

https://lab.llvm.org/buildbot/#/builders/216/builds/7412

I've removed it in 33aa374e597260dae739bb949892cff31ae31eb9 . Someone feeling a need to have a coverage can add it.

Please don't remove test coverage like this - this test covers the error path here: https://github.com/llvm/llvm-project/blob/33aa374e597260dae739bb949892cff31ae31eb9/llvm/lib/DWP/DWP.cpp#L288

It's a fast way to get bots green. It takes time to construct a test.

The usual way to do that if this would take to long is to revert the causal patch while addressing the regression - not lower test coverage permanently.

The file will need to be re-added anyway to avoid the precanned binary. Adding a test in one minute, I am not sure it's useful to revert this current patch.

Ah, OK - thanks! Nah, I don't mind fixing forward here, though I think in the future it'd be simpler/clearer if the patch were reverted and recommitted correctly rather than temporarily removing testing like this.

This patch (simple enough but still touched quite a few files), maybe. But I realized that such a "failing-to-testing-a-case-people-don't-tend-to-use" may not be sufficient for some other tests.
The net result fixing forward here isn't too bad. The history is quite clean, just that the nocompress.test file has some 1 unneeded log.

llvm/include/llvm/Object/Decompressor.h

public:
 
   /// Uncompress section data to raw buffer provided.
   /// @param Buffer      Destination buffer.
   Error decompress(MutableArrayRef<uint8_t> Buffer);
 
   /// Return memory buffer size required for decompression.
   uint64_t getDecompressedSize() { return DecompressedSize; }
 
-  /// Return true if section is compressed, including gnu-styled case.
-  static bool isCompressed(const object::SectionRef &Section);
-
-  /// Return true if section is a ELF compressed one.
-  static bool isCompressedELFSection(uint64_t Flags, StringRef Name);
-
-  /// Return true if section name matches gnu style compressed one.
-  static bool isGnuStyle(StringRef Name);
-
 private:
   Decompressor(StringRef Data);
 
-  Error consumeCompressedGnuHeader();
   Error consumeCompressedZLibHeader(bool Is64Bit, bool IsLittleEndian);
 
   StringRef SectionData;
   uint64_t DecompressedSize;
 };
 
 } // end namespace object
 } // end namespace llvm
 
 #endif // LLVM_OBJECT_DECOMPRESSOR_H

llvm/lib/DWP/DWP.cpp

 //
 //===----------------------------------------------------------------------===//
 #include "llvm/DWP/DWP.h"
 #include "llvm/DWP/DWPError.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCTargetOptionsCommandFlags.h"
 #include "llvm/Object/Decompressor.h"
+#include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Support/MemoryBuffer.h"
 
 using namespace llvm;
 using namespace llvm::object;
 
 static mc::RegisterMCTargetOptionsFlags MCTargetOptionsFlags;
 
 // Returns the size of debug_str_offsets section headers in bytes.
static Error createError(StringRef Name, Error E) {
   return make_error<DWPError>(
       ("failure while decompressing compressed section: '" + Name + "', " +
        llvm::toString(std::move(E)))
           .str());
 }
 
 static Error
 handleCompressedSection(std::deque<SmallString<32>> &UncompressedSections,
-                        StringRef &Name, StringRef &Contents) {
-  if (!Decompressor::isGnuStyle(Name))
+                        SectionRef Sec, StringRef Name, StringRef &Contents) {
+  auto *Obj = dyn_cast<ELFObjectFileBase>(Sec.getObject());
+  if (!Obj ||
+      !(static_cast<ELFSectionRef>(Sec).getFlags() & ELF::SHF_COMPRESSED))
     return Error::success();
-
-  Expected<Decompressor> Dec =
-      Decompressor::create(Name, Contents, false /*IsLE*/, false /*Is64Bit*/);
+  bool IsLE = isa<object::ELF32LEObjectFile>(Obj) ||
+              isa<object::ELF64LEObjectFile>(Obj);
+  bool Is64 = isa<object::ELF64LEObjectFile>(Obj) ||
+              isa<object::ELF64BEObjectFile>(Obj);
+  Expected<Decompressor> Dec = Decompressor::create(Name, Contents, IsLE, Is64);
   if (!Dec)
     return createError(Name, Dec.takeError());
 
   UncompressedSections.emplace_back();
   if (Error E = Dec->resizeAndDecompress(UncompressedSections.back()))
     return createError(Name, std::move(E));
 
-  Name = Name.substr(2); // Drop ".z"
   Contents = UncompressedSections.back();
   return Error::success();
 }
 
 namespace llvm {
 // Parse and return the header of an info section compile/type unit.
 Expected<InfoSectionUnitHeader> parseInfoSectionUnitHeader(StringRef Info) {
   InfoSectionUnitHeader Header;
if (!NameOrErr)
     return NameOrErr.takeError();
   StringRef Name = *NameOrErr;
 
   Expected<StringRef> ContentsOrErr = Section.getContents();
   if (!ContentsOrErr)
     return ContentsOrErr.takeError();
   StringRef Contents = *ContentsOrErr;
 
-  if (auto Err = handleCompressedSection(UncompressedSections, Name, Contents))
+  if (auto Err = handleCompressedSection(UncompressedSections, Section, Name,
+                                         Contents))
     return Err;
 
   Name = Name.substr(Name.find_first_not_of("._"));
 
   auto SectionPair = KnownSections.find(Name);
   if (SectionPair == KnownSections.end())
     return Error::success();
 

llvm/lib/DebugInfo/DWARF/DWARFContext.cpp

return StringSwitch<StringRef *>(Name)
         // Any more debug info sections go here.
         .Default(nullptr);
   }
 
   /// If Sec is compressed section, decompresses and updates its contents
   /// provided by Data. Otherwise leaves it unchanged.
   Error maybeDecompress(const object::SectionRef &Sec, StringRef Name,
                         StringRef &Data) {
-    if (!Decompressor::isCompressed(Sec))
+    if (!Sec.isCompressed())
       return Error::success();
 
     Expected<Decompressor> Decompressor =
         Decompressor::create(Name, Data, IsLittleEndian, AddressSize == 8);
     if (!Decompressor)
       return Decompressor.takeError();
 
     SmallString<0> Out;

llvm/lib/Object/Decompressor.cpp

 using namespace object;
 
 Expected<Decompressor> Decompressor::create(StringRef Name, StringRef Data,
                                             bool IsLE, bool Is64Bit) {
   if (!compression::zlib::isAvailable())
     return createError("zlib is not available");
 
   Decompressor D(Data);
-  Error Err = isGnuStyle(Name) ? D.consumeCompressedGnuHeader()
-                               : D.consumeCompressedZLibHeader(Is64Bit, IsLE);
-  if (Err)
+  if (Error Err = D.consumeCompressedZLibHeader(Is64Bit, IsLE))
     return std::move(Err);
   return D;
 }
 
 Decompressor::Decompressor(StringRef Data)
     : SectionData(Data), DecompressedSize(0) {}
 
-Error Decompressor::consumeCompressedGnuHeader() {
-  if (!SectionData.startswith("ZLIB"))
-    return createError("corrupted compressed section header");
-
-  SectionData = SectionData.substr(4);
-
-  // Consume uncompressed section size (big-endian 8 bytes).
-  if (SectionData.size() < 8)
-    return createError("corrupted uncompressed section size");
-  DecompressedSize = read64be(SectionData.data());
-  SectionData = SectionData.substr(8);
-
-  return Error::success();
-}
-
 Error Decompressor::consumeCompressedZLibHeader(bool Is64Bit,
                                                 bool IsLittleEndian) {
   using namespace ELF;
   uint64_t HdrSize = Is64Bit ? sizeof(Elf64_Chdr) : sizeof(Elf32_Chdr);
   if (SectionData.size() < HdrSize)
     return createError("corrupted compressed section header");
 
   DataExtractor Extractor(SectionData, IsLittleEndian, 0);
   uint64_t Offset = 0;
   if (Extractor.getUnsigned(&Offset, Is64Bit ? sizeof(Elf64_Word)
                                              : sizeof(Elf32_Word)) !=
       ELFCOMPRESS_ZLIB)
     return createError("unsupported compression type");
 
   // Skip Elf64_Chdr::ch_reserved field.
   if (Is64Bit)
     Offset += sizeof(Elf64_Word);
 
   DecompressedSize = Extractor.getUnsigned(
       &Offset, Is64Bit ? sizeof(Elf64_Xword) : sizeof(Elf32_Word));
   SectionData = SectionData.substr(HdrSize);
   return Error::success();
 }
 
-bool Decompressor::isGnuStyle(StringRef Name) {
-  return Name.startswith(".zdebug");
-}
-
-bool Decompressor::isCompressed(const object::SectionRef &Section) {
-  if (Section.isCompressed())
-    return true;
-
-  Expected<StringRef> SecNameOrErr = Section.getName();
-  if (SecNameOrErr)
-    return isGnuStyle(*SecNameOrErr);
-
-  consumeError(SecNameOrErr.takeError());
-  return false;
-}
-
-bool Decompressor::isCompressedELFSection(uint64_t Flags, StringRef Name) {
-  return (Flags & ELF::SHF_COMPRESSED) || isGnuStyle(Name);
-}
-
 Error Decompressor::decompress(MutableArrayRef<uint8_t> Buffer) {
   size_t Size = Buffer.size();
   return compression::zlib::uncompress(arrayRefFromStringRef(SectionData),
                                        Buffer.data(), Size);
 }

llvm/test/tools/llvm-dwp/X86/compress.test

-REQUIRES: zlib
-RUN: llvm-dwp %p/../Inputs/compress/a.dwo -o %t
-RUN: llvm-dwarfdump -v %t | FileCheck %s
-
-Simple test built from this input which produces DWARF long enough to be compressed in the .[z]debug_info section:
-
-  void f(int a, int b, int c, int d) {
-  }
-
-Since the compression is pretty orthogonal, we're not trying to test that the
-compression library functioned correctly, just that dwp used it to decompress
-the section - so test a few simple features and be done with it.
-
-CHECK: .debug_info.dwo contents:
-CHECK: Compile Unit:
-CHECK:   DW_TAG_compile_unit
-CHECK:     DW_TAG_subprogram
-CHECK:       DW_TAG_formal_parameter
+# REQUIRES: zlib
+# RUN: yaml2obj -DCLASS=32 -DENDIAN=LSB -DINFO_CHDR=010000005600000001000000 %s -o %t.o
+# RUN: llvm-dwp %t.o -o %t
+# RUN: llvm-dwarfdump -v %t | FileCheck %s
+
+# RUN: yaml2obj -DCLASS=32 -DENDIAN=MSB -DINFO_CHDR=000000010000005600000001 %s -o %t.o
+# RUN: llvm-dwp %t.o -o %t
+# RUN: llvm-dwarfdump -v %t | FileCheck %s
+
+# RUN: yaml2obj -DCLASS=64 -DENDIAN=LSB -DINFO_CHDR=01000000fd7f000056000000000000000100000000000000 %s -o %t.o
+# RUN: llvm-dwp %t.o -o %t
+# RUN: llvm-dwarfdump -v %t | FileCheck %s
+
+# RUN: yaml2obj -DCLASS=64 -DENDIAN=MSB -DINFO_CHDR=0000000100007ffd00000000000000560000000000000001 %s -o %t.o
+# RUN: llvm-dwp %t.o -o %t
+# RUN: llvm-dwarfdump -v %t | FileCheck %s
+
+## Simple test built from this input which produces DWARF long enough to be compressed in the .[z]debug_info section:
+##
+##   void f(int a, int b, int c, int d) {
+##   }
+
+## Since the compression is pretty orthogonal, we're not trying to test that the
+## compression library functioned correctly, just that dwp used it to decompress
+## the section - so test a few simple features and be done with it.
+
+# CHECK: .debug_info.dwo contents:
+# CHECK: Compile Unit:
+# CHECK:   DW_TAG_compile_unit
+# CHECK:     DW_TAG_subprogram
+# CHECK:       DW_TAG_formal_parameter
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS[[CLASS]]
+  Data:            ELFDATA2[[ENDIAN]]
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .debug_loc.dwo
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x1
+  - Name:            .debug_str.dwo
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_MERGE, SHF_STRINGS ]
+    AddressAlign:    0x1
+    EntSize:         0x1
+    Content:         636C616E672076657273696F6E20332E392E3020287472756E6B203236313232332920286C6C766D2F7472756E6B203236313233342900612E637070005F5A3166696969690066006100696E7400620063006400
+  - Name:            .debug_str_offsets.dwo
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x1
+    Content:         00000000370000003D00000046000000480000004A0000004E0000005000000052000000
+  - Name:            .debug_info.dwo
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_COMPRESSED ]
+    AddressAlign:    0x8
+    Content:         [[INFO_CHDR]]789c0b626060606100010e462083f1e6eb7f7c0d8b756299188480628c614ccc8c8ccc4c136b5818190381024066051b9c59c20e67167040980c2cacac2c0c00109a0afa
+  - Name:            .debug_abbrev.dwo
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x1
+    Content:         01110125823E130503823EB142070000022E0111813E120640186E823E03823E3A0B3B0B3F190000030500021803823E3A0B3B0B4913000004240003823E3E0B0B0B000000
+  - Name:            .debug_line.dwo
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x1
+    Content:         0D0000000200070000000101FB0E010000

llvm/test/tools/llvm-dwp/X86/compressfail.test

-REQUIRES: zlib
-RUN: not llvm-dwp %p/../Inputs/compressfail/a.dwo -o %t 2>&1 | FileCheck %s
-RUN: not llvm-dwp %p/../Inputs/empty_compressed_section.dwo -o %t 2>&1 | FileCheck %s
-RUN: not llvm-dwp %p/../Inputs/invalid_compressed.dwo -o %t 2>&1 | FileCheck %s
+# REQUIRES: zlib
+# RUN: yaml2obj --docnum=1 %s -o %t1.o
+# RUN: not llvm-dwp %t1.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR1
+# RUN: yaml2obj --docnum=2 %s -o %t2.o
+# RUN: not llvm-dwp %t2.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR2
 
-CHECK: error: failure while decompressing compressed section: '.zdebug_{{.*}}.dwo'
+# ERR1: error: failure while decompressing compressed section: '.debug_info.dwo', corrupted compressed section header
+# ERR2: error: failure while decompressing compressed section: '.debug_info.dwo', zlib error: Z_DATA_ERROR
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name:         .debug_info.dwo
+    Type:         SHT_PROGBITS
+    Flags:        [ SHF_COMPRESSED ]
+    AddressAlign: 8
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name:         .debug_info.dwo
+    Type:         SHT_PROGBITS
+    Flags:        [ SHF_COMPRESSED ]
+    AddressAlign: 8
+    Content:      "010000000000000004000000000000000100000000000000ffff"