[clang] [llvm] [FMV][AArch64] Simplify version selection according to ACLE. (PR #121921)

[Jon Roelofs via llvm-commits]

================
@@ -49,16 +49,11 @@ std::optional<AArch64::ArchInfo> AArch64::ArchInfo::findBySubArch(StringRef SubA
 }
 
 unsigned AArch64::getFMVPriority(ArrayRef<StringRef> Features) {
----------------
jroelofs wrote:

I'm not sure that this interface can correctly describe the new rule. ISTM it would have to be a comparison function between two feature sets, as with this implementation, `getFMVPriority({"sme","flagm2","flagm"}) == getFMVPriority({"sme","flagm"})` but really we want that to be `>=`.

https://github.com/llvm/llvm-project/pull/121921