arch,cpu: Stop using TheISA::Decoder in most places.

The only places that still use that indirection are where the decoder
itself is instantiated with "new".

Also, add an "as" method which makes casting to an ISA specific decoder
type easier and less error prone.

Change-Id: Ib4a9cce7f96da2a9a8fe19113628694904893b17
Reviewed-by: Daniel Carvalho <>
Maintainer: Gabe Black <>
Tested-by: kokoro <>
20 files changed