CP_REG_TEST (or any command that reads registers) is slow on a618
(gen1). Since SQE can early return, we don't necessarily need
emit_conditional_ib in fd6_emit_tile.
We still CP_REG_TEST twice for load and store when there is no clear.
Not sure if we can simply drop emit_conditional_ib instead?
glmark2 score goes from 943 to 1067.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21208>
Chia-I Wu
af7bcc0cdc