[clang] [llvm] [AArch64TargetParser]Fix reconstructFromParsedFeatures ignoring negative features (PR #142236)

[Matthias Braun via llvm-commits]

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@@ -60,7 +60,7 @@ uint64_t AArch64::getFMVPriority(ArrayRef<StringRef> Features) {
   ExtensionSet FeatureBits;
   for (const StringRef Feature : Features) {
     std::optional<FMVInfo> FMV = parseFMVExtension(Feature);
-    if (!FMV) {
+    if (!FMV && Feature.starts_with('+')) {
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MatzeB wrote:

I don't think it's explicitly stated that empty strings are forbidden, so wouldn't like to just make assumptions also as I don't expect this function to performance critical...

https://github.com/llvm/llvm-project/pull/142236