[lld] [llvm] [lld][AArch64][Build Attributes] Add support for converting AArch64 Build Attributes to GNU Properties (PR #131990)

[Oliver Stannard via llvm-commits]

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@@ -638,27 +807,76 @@ template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
         }
       }
       break;
-    case EM_AARCH64:
-      // FIXME: BuildAttributes have been implemented in llvm, but not yet in
-      // lld. Remove the section so that it does not accumulate in the output
-      // file. When support is implemented we expect not to output a build
-      // attributes section in files of type ET_EXEC or ET_SHARED, but ld -r
-      // ouptut will need a single merged attributes section.
-      if (sec.sh_type == SHT_AARCH64_ATTRIBUTES)
+    case EM_AARCH64: {
+      // The specification states that if a file contains both GNU properties
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ostannard wrote:

To be clear, while I'm happy for this error checking to not be included in this PR, it's still very important because silently ignoring a build attribute can result in a security feature being disabled.

https://github.com/llvm/llvm-project/pull/131990