[clang] [llvm] [AArch64] set AppleA14 architecture version to v8.4-a (PR #92600)

[Tomas Matheson via llvm-commits]

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@@ -718,12 +718,16 @@ def ProcessorFeatures {
   list<SubtargetFeature> AppleA13 = [HasV8_4aOps, FeatureCrypto, FeatureFPARMv8,
                                      FeatureNEON, FeaturePerfMon, FeatureFullFP16,
                                      FeatureFP16FML, FeatureSHA3];
+  // Apple A14 and M1 chips are based on Armv8.5-a but without BTI. Since there
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tmatheson-arm wrote:

I don't buy the argument that we shouldn't document something because there are lots of other things lacking documentation. What other quirks are you aware of? Maybe they should be commented too.

https://github.com/llvm/llvm-project/pull/92600