intel/brw: Fix usage and validation of accumulator register
Two patches:
First, fix the usage of accumulator register in sub_sat lowering. Use the existing helper to ensure that <V,W,H> triple is correctly set. The commit message goes in some detail about what changes in the output of lowering.
Then, fix validation of accumulator register to look at hstride
instead of stride
which is not meant to be used by ARFs (and always set to 1, so test would always pass).
Edited by Caio Oliveira