On Jan 21, 2016 4:37 PM, "Kenneth Graunke" <<a href="mailto:kenneth@whitecape.org">kenneth@whitecape.org</a>> wrote: > > I don't know why, but we never hooked up this pass Eric wrote. > Otherwise, you can end up with stupid scalarized code such as: > > vec4 ssa_7 = load_const (0.0, 0.0, 0.0, 0.0) > vec4 ssa_8 = ... > vec1 ssa_9 = feq ssa_8, ssa_7 > vec1 ssa_10 = feq ssa_8.y, ssa_7.y > vec1 ssa_11 = feq ssa_8, ssa_7.z > vec1 ssa_12 = feq ssa_8.y, ssa_7.w > > ssa_8.xyxy == <0, 0, 0, 0> should only take two feq instructions. > > shader-db on Skylake: > > total instructions in shared programs: 9111788 -> 9111384 (-0.00%) > instructions in affected programs: 32421 -> 32017 (-1.25%) > helped: 277 > HURT: 69 > > total cycles in shared programs: 69221226 -> 69219394 (-0.00%) > cycles in affected programs: 917796 -> 915964 (-0.20%) > helped: 317 > HURT: 408 > > This also prevents regressions when disabling channel expressions. > > Signed-off-by: Kenneth Graunke <<a href="mailto:kenneth@whitecape.org">kenneth@whitecape.org</a>> > --- > src/mesa/drivers/dri/i965/brw_nir.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/src/mesa/drivers/dri/i965/brw_nir.c b/src/mesa/drivers/dri/i965/brw_nir.c > index 935529a..ce9b9db 100644 > --- a/src/mesa/drivers/dri/i965/brw_nir.c > +++ b/src/mesa/drivers/dri/i965/brw_nir.c > @@ -482,6 +482,11 @@ brw_preprocess_nir(nir_shader *nir, bool is_scalar) > > nir = nir_optimize(nir, is_scalar); > > + if (is_scalar) { > + OPT_V(nir_lower_load_const_to_scalar); > + OPT(nir_opt_cse); > + } Why did you choose to put this *after* the opt loop? It seems like we would want it before so that we can use better. As long as alu_to_scalar is run before constant folding (so we don't end up re-vectorizing them), before should be fine. > + > /* Lower a bunch of stuff */ > OPT_V(nir_lower_var_copies); > > -- > 2.7.0 > > _______________________________________________ > mesa-dev mailing list > <a href="mailto:mesa-dev@lists.freedesktop.org">mesa-dev@lists.freedesktop.org</a> > <a href="http://lists.freedesktop.org/mailman/listinfo/mesa-dev">http://lists.freedesktop.org/mailman/listinfo/mesa-dev</a>