On Fri, Jan 22, 2016 at 8:42 PM, Jason Ekstrand <ja...@jlekstrand.net> wrote: > On Fri, Jan 22, 2016 at 5:35 PM, Matt Turner <matts...@gmail.com> wrote: >> On Thu, Jan 21, 2016 at 4:37 PM, Kenneth Graunke <kenn...@whitecape.org> >> wrote: >> > nir_lower_alu_to_scalar() and nir_lower_load_const_to_scalar() >> > handle most cases quite well. They also create nir_ssa_defs rather >> > than ir_variables, which are much less memory intensive. >> > >> > This can mean losing out on a few GLSL IR optimizations, however. >> > In most cases, this is fine. But a few cases still benefit: >> > >> > - add/mul/dot still benefit from opt_algebraic()'s constant >> > reassociation capabilities. >> > >> > - min/max still benefit from opt_minmax(). >> > >> > - comparisons seem to still benefit from opt_algebraic(), even >> > though we also do most of them in nir_opt_algebraic_late(). >> > >> > With this change, shader-db statistics on Skylake are: >> > >> > total instructions in shared programs: 9107924 -> 9107347 (-0.01%) >> > instructions in affected programs: 188830 -> 188253 (-0.31%) >> > helped: 572 >> > HURT: 154 >> >> I tried looking at the hurt programs. The first was >> guacamelee/368.shader_test, which went from 40 -> 43 instructions. It >> has a multiplication tree of (x * (y * 0.2) * 15.0), which we are able >> to convert into x * y * 3.0 after channel expressions. >> >> The shader looks like >> >> star_1 = (thing0 * 0.2) * thing1 >> star_1 = star_1 * 15.0 >> >> star_2 = (thing2 * 0.2) * thing3 >> star_2 = star_2 * 15.0 >> >> star_3 = (thing4 * 0.2) * thing5 >> star_3 = star_3 * 15.0 >> >> stars = sat(star_1) + sat(star_2) + sat(stars_3) >> >> Before linking and channel expressions, we don't have appropriate >> trees to see that we can reassociate constants. Tree grafting won't do >> its job on, for instance, star_1, because it sees that star_1 is >> assigned more than once -- even though it's just reassigning itself. >> >> Adding ir_unop_saturate back to channel_expressions solves the issue. >> I continued looking at the regressions and adding things back until I >> was down to 25 hurt programs (but also down to only 10 helped) after >> I'd readded sign, lrp, neg, f2i, i2f, exp2, log2, f2u, u2f. > > > Adding those back in gets rid of hurt programs, but does adding them back in > get rid of helped programs?
Yes, adding them back both helps and hurts programs. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
