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

[Tomas Matheson via llvm-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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tmatheson-arm wrote:

IIUC, the idea here is that we don't want to add the architecture's default extensions to the CPU, because they are not mandatory, and there's no way to disable them for a CPU that chooses not to implement. This is why all the CPUs have had their list of features expanded.

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