615117ce4e
There's an assumption here that fixed GRFs will never intersect with
the allocated GRFs. That's true today, though it might change some
day if we decide to register-allocate the regs containing push
constants once they're dead.
This fixes a regression in 0f7325b890 in
Lightsmark from the texture instructions now containing g0 references
instead of having that be implied. Performance is improved 15.2% +/-
3.6% (n=3).
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=34968