arch-power: Add fields for MD and MDS form instructions

This introduces the extended opcode fields for MD and
MDS form instructions and the mb and me fields which
are concatenated with the MB and ME fields respectively
for specifying mask bounds for doubleword operands.

Change-Id: I2c3366794ed42f5d31ba1d69e360c0ac67c74e06
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40932
Reviewed-by: Boris Shingarov <shingarov@labware.com>
Maintainer: Boris Shingarov <shingarov@labware.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed