[llvm] [AMDGPU] Add an asm directive to track code_object_version (PR #76267)

[Fangrui Song via llvm-commits]

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@@ -279,6 +280,10 @@ class MCAssembler {
   unsigned getELFHeaderEFlags() const { return ELFHeaderEFlags; }
   void setELFHeaderEFlags(unsigned Flags) { ELFHeaderEFlags = Flags; }
 
+  /// ELF e_ident[EI_ABIVERSION] value
+  unsigned char getELFHeaderABIVersion() const { return ELFHeaderABIVersion; }
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MaskRay wrote:

See `llvm/lib/MC/MCELFStreamer.cpp:Asm.getWriter().markGnuAbi()`. This can be moved to `ELFObjectWriter` and revert the `MCELFObjectTargetWriter` change below.

https://github.com/llvm/llvm-project/pull/76267