As a continuation of D132034, this switches the QRDMX v8.1a neon intrinsics over from preprocessor defines to be target-gated. As there is no "rdma" or "qrdmx" target feature, they use the "v8.1a" architecture feature directly.
This works well for AArch64, but something needs to be done for Arm at the same time, as they both use the same header and tablegen emitter. This patch opts for adding "v8.1a" and all dependant target features to the Arm TargetParser, similar to what was recently done for AArch64 but through initFeatureMap when the Architecture is parsed. I attempted to make the code similar to the AArch64 backend. Alternative suggestions are welcome.
Otherwise this is similar to the changes made in D132034.
This patch mostly looks comprehensible to me, but I don't understand what this change has to do with it. Everything else seems to be controlling how intrinsics are enabled/disabled, but the changes in this file seem to be renaming some intrinsics, and there's nothing about that in the commit message.
Is this intentionally part of the same patch?