arch: Split utility methods/variables out of the ISA parser.

Change-Id: Ifbff4bc6633cd11f98b02ba1291a91c3ad189285
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35279
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed