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

[Alexandros Lamprineas via llvm-commits]

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

Ah I see what you mean, we should first compare the highest priority feature between the two sets. In this example that is sme. Since it is common between the two sets, we then compare the next highest of each set. This is flagm2 for the first set and flagm for the second. Therefore the first set wins. Basically what I have described is comparing two bitmasks. Unfortunately the return value (unsigned) is narrower than the bitmask (uint64_t) and it is common interface with other targets. I'll see if I can change it.

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