arch-vega: Implement SOP2 S_MUL_HI instructions

Two new 32-bit signed and unsigned variants of S_MUL were added in
gfx900 which operate similar to S_MUL expect they shift the product by
32 bits after multiplication. Tested with Histogram HIP-Sample and
b+tree in rodinia 3.0 HIP port.

Change-Id: I1bed32b17ccda7aa47f3b59528eb3304912d3610
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/58473
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed