[clang] [llvm] Split fmv and extensions (PR #92882)

[Alexandros Lamprineas via cfe-commits]

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@@ -1062,35 +1064,41 @@ bool AArch64TargetInfo::initFeatureMap(
     llvm::AArch64::getExtensionFeatures(Exts, CPUFeats);
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labrinea wrote:

I am wondering if calling ExtensionSet::addCPUDefaults here would be preferable. It's not NFC. I saw a test failing because the attribute string for cortex-a710 would contain +v8.1a,+v8.2a,+v8.3a,+v8.4a,+v8.5a,+v8a,+v9a whereas before it didn't. That was `clang/test/CodeGen/aarch64-targetattr.c` for `__attribute__((target("cpu=cortex-a710")))`.

https://github.com/llvm/llvm-project/pull/92882