arch-gcn3: Implement LDS accesses in Flat instructions

Add support for LDS accesses by allowing Flat instructions to dispatch
into the local memory pipeline if the requested address is in the group
aperture.

This requires implementing LDS accesses in the Flat initMemRead/Write
functions, in a similar fashion to the DS functions of the same name.

Because we now can potentially dispatch to the local memory pipeline,
this change also adds a check to regain any tokens we requested as a
flat instruction.

Change-Id: Id26191f7ee43291a5e5ca5f39af06af981ec23ab
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48343
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
4 files changed