[llvm] [AArch64] Prevent reuse of retired architecture names (PR #221782)

[via llvm-commits]

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@@ -0,0 +1,21 @@
+// RUN: not llvm-mc -triple=aarch64 -mattr=+mpamv2,+tme < %s 2>&1 | FileCheck %s
+
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CarolineConcatto wrote:

I think this is the last one.
Maybe we should split this into 2 tests. One just for features, using them in the run line and another just for the system registers. For the system registers we use -mattr=+all, this will prevent some system register under a feature flag to create a false negative.

https://github.com/llvm/llvm-project/pull/221782