arch,cpu,sim: Use PCStateBase in advancePC.

By using a PCStateBase pointer or reference, we can (mostly) avoid
having to know what the ISA specific PState class is, letting the ISA
specific instruction classes cast to the type they need internally.

There are a couple minor places where we need to do those casts outside
of ISA specific types, one in the generic NopStaticInstPtr class, and a
few in generic faults.

Right now, we'll just use the TheISA::PCState type in those isolated
spots (sometimes hidden by auto), and deal with it later, possibly
with a virtual "advance" method of some sort.

Change-Id: I774c67dc648a85556230f601e087211b3d5630a9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52043
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
17 files changed