[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:

Is there a problem with emphasising it? The main motivation is to avoid people repeating the mistake that I made, i.e. seeing 8.4 here and 8.5 in publicly available documentation and "correcting" it.

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