[Lldb-commits] [PATCH] D126367: [lldb] Add gnu-debuglink support for Windows PE/COFF

[Martin Storsjö via Phabricator via lldb-commits]

mstorsjo added a comment.

When testing this patch, I ran into crashes in the `SymbolFile/NativePDB/load-pdb.cpp` testcase. To fix it, I had to add a change like this:

  diff --git a/lldb/source/Plugins/SymbolVendor/PECOFF/SymbolVendorPECOFF.cpp b/lldb/source/Plugins/SymbolVendor/PECOFF/SymbolVendorPECOFF.cpp
  index 26df0035b37c..e08753b86d5b 100644
  --- a/lldb/source/Plugins/SymbolVendor/PECOFF/SymbolVendorPECOFF.cpp
  +++ b/lldb/source/Plugins/SymbolVendor/PECOFF/SymbolVendorPECOFF.cpp
  @@ -108,6 +108,8 @@ SymbolVendorPECOFF::CreateInstance(const lldb::ModuleSP &module_sp,
     // that.
     SectionList *module_section_list = module_sp->GetSectionList();
     SectionList *objfile_section_list = dsym_objfile_sp->GetSectionList();
  +  if (!objfile_section_list || !module_section_list)
  +    return nullptr;
   
     static const SectionType g_sections[] = { 
         eSectionTypeDWARFDebugAbbrev,   eSectionTypeDWARFDebugAranges,

Also, when built with assertions enabled (which often is to prefer during development, to catch things before the buildbots do), reading the debuglink info failed an assert:

  lldb/source/Utility/DataExtractor.cpp:135: lldb_private::DataExtractor::DataExtractor(const void*, lldb::offset_t, lldb::ByteOrder, uint32_t, uint32_t): Assertion `addr_size >= 1 && addr_size <= 8' failed.

This is easy to fix with a change like this:

  diff --git a/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp b/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
  index ba4612178be7..657fcdc5af6d 100644
  --- a/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
  +++ b/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
  @@ -63,7 +63,7 @@ static bool GetDebugLinkContents(const llvm::object::COFFObjectFile &coff_obj,
         }
         DataExtractor data(
             content->data(), content->size(),
  -          coff_obj.isLittleEndian() ? eByteOrderLittle : eByteOrderBig, 0);
  +          coff_obj.isLittleEndian() ? eByteOrderLittle : eByteOrderBig, 4);
         lldb::offset_t gnu_debuglink_offset = 0;
         gnu_debuglink_file = data.GetCStr(&gnu_debuglink_offset);
         // Align to the next 4-byte offset

If it's ok with you, I can squash these changes (plus a rewording regarding GNU ld and the codeview build ID) and push the patch.



================
Comment at: lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp:96
+
+  // The GNU linker does not write a PDB build id, so we should fall back to
+  // using the crc from .gnu_debuglink if it exists, just like how ObjectFileELF
----------------
Actually, the GNU linker does write such a build id if you pass it `-Wl,--build-id`, but it's not default like in LLD.


Repository:
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https://reviews.llvm.org/D126367