[clang] [llvm] [llvm][AArch64] apple-m4 is armv9.2-a (PR #98267)

[Jon Roelofs via cfe-commits]

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@@ -161,14 +161,10 @@ struct CpuInfo {
   StringRef Name; // Name, as written for -mcpu.
   const ArchInfo &Arch;
   AArch64::ExtensionBitset
-      DefaultExtensions; // Default extensions for this CPU. These will be
-                         // ORd with the architecture defaults.
+      DefaultExtensions; // Default extensions for this CPU.
 
   AArch64::ExtensionBitset getImpliedExtensions() const {
-    AArch64::ExtensionBitset ImpliedExts;
-    ImpliedExts |= DefaultExtensions;
-    ImpliedExts |= Arch.DefaultExts;
-    return ImpliedExts;
+    return DefaultExtensions;
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jroelofs wrote:

This choice also makes `-march=` meaningless, so @ahmedbougacha and I are considering making that an error at least on Darwin platforms.

https://github.com/llvm/llvm-project/pull/98267