[llvm] [LLVM][DWARF] Add support for .gnu_debuglink (PR #77715)

[Alexander Yermolovich via llvm-commits]

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@@ -127,6 +127,9 @@ class DWARFContext : public DIContext {
 
   std::unique_ptr<const DWARFObject> DObj;
 
+  /// Binary containing debug information after objcopy --only-keep-debug
+  object::OwningBinary<object::ObjectFile> GnuLink;
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ayermolo wrote:

@dwblaikie I realize in ::create is not super ideal. I was originally thinking about doing it in the constructor, but then if people go through ::create then DWARFObjInMemory is created for no reason.
Generally speaking I think this should be handled similar to .dwp where it's under the hood and consumers of debug information shouldn't really care/know if debug info is in main binary or in a separate elf object.

https://github.com/llvm/llvm-project/pull/77715