[clang] [llvm] [AArch64] Correctly mark Neoverse N2 as an Armv9.0a core (PR #75055)

[David Spickett via cfe-commits]

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@@ -94,6 +94,11 @@ Changes to the AArch64 Backend
 
 * Added support for Cortex-A520, Cortex-A720 and Cortex-X4 CPUs.
 
+* Neoverse-N2 was incorrectly marked as an Armv8.5a core. This has been
+  changed to an Armv9.0a core. However, crypto options are not enabled
+  by default for Armv9 cores, so `-mcpu=neoverse-n2+crypto` is required
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DavidSpickett wrote:

It's my understanding that v8.5-a == v9.0-a as far as the compiler is concerned (there are a couple of extra requirements to be v9.0-a that don't concern the compiler). Is that correct?

Might be worth stating that they enable the same features, with the exception of crypto as mentioned.
(not saying that they are literally the same, just same as far as a compiler is concerned)

https://github.com/llvm/llvm-project/pull/75055