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? --Jason > > I think that by the time I was down to zero regressions, the only > things I would have not readded would be opcodes unused in shader-db. > > I think I want to hold off on this patch. > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev >
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