[clang] [llvm] [AArch64] Decouple feature dependency expansion. (PR #94279)

[Tomas Matheson via llvm-commits]

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@@ -106,7 +106,7 @@ def FeatureFPARMv8 : Extension<"fp-armv8", "FPARMv8",
   "Enable ARMv8 (FEAT_FP)", [],
   "FEAT_FP", "+fp-armv8,+neon", 90>;
 
-let ArchExtKindSpelling = "AEK_SIMD", MArchName = "simd" in
+let ArchExtKindSpelling = "AEK_SIMD", MArchName = "simd", MArchAlias = "neon" in
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tmatheson-arm wrote:

This will enable the alias on `-march` too. Instead we should disallow clang internal names in the target attribute.

https://github.com/llvm/llvm-project/pull/94279