From a4d478732712799d47f32cdbd2a7dca01239dc70 Mon Sep 17 00:00:00 2001 From: Ian Romanick Date: Tue, 3 Jul 2018 11:49:07 -0700 Subject: [PATCH] intel/compiler: More DCE after lowering MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Some of the lowering passes, nir_lower_locals_to_regs for example, can cause some previously live code to be dead. This pass in particular leaves a bunch of nir_instr_type_deref instructions floating around. This causes shader-db runs on Gen5 through Haswell to spew tons of messages like: VS instruction not yet implemented by NIR->vec4 UnrealEngine4/EffectsCaveDemo/239.shader_test is one shader that generates these messages. Cleaning up the dead code fixes that. To verify, I did a shader-db before and after. Even though all the messages are gone, the results make my brain hurt. :( Haswell total cycles in shared programs: 411890163 -> 411891145 (<.01%) cycles in affected programs: 57016 -> 57998 (1.72%) helped: 3 HURT: 11 helped stats (abs) min: 2 max: 154 x̄: 96.67 x̃: 134 helped stats (rel) min: 0.08% max: 2.23% x̄: 1.42% x̃: 1.96% HURT stats (abs) min: 18 max: 686 x̄: 115.64 x̃: 20 HURT stats (rel) min: 0.81% max: 7.12% x̄: 1.87% x̃: 0.93% 95% mean confidence interval for cycles value: -51.39 191.67 95% mean confidence interval for cycles %-change: -0.14% 2.46% Inconclusive result (value mean confidence interval includes 0). Ivy Bridge total cycles in shared programs: 259114802 -> 259115032 (<.01%) cycles in affected programs: 24034 -> 24264 (0.96%) helped: 1 HURT: 9 helped stats (abs) min: 2 max: 2 x̄: 2.00 x̃: 2 helped stats (rel) min: 0.08% max: 0.08% x̄: 0.08% x̃: 0.08% HURT stats (abs) min: 18 max: 48 x̄: 25.78 x̃: 20 HURT stats (rel) min: 0.80% max: 1.94% x̄: 1.08% x̃: 0.80% 95% mean confidence interval for cycles value: 12.42 33.58 95% mean confidence interval for cycles %-change: 0.54% 1.38% Cycles are HURT. Signed-off-by: Ian Romanick Fixes: 5a02ffb733e nir: Rework lower_locals_to_regs to use deref instructions Reviewed-by: Jason Ekstrand --- src/intel/compiler/brw_nir.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c index f2553519fac..74b39ad80a2 100644 --- a/src/intel/compiler/brw_nir.c +++ b/src/intel/compiler/brw_nir.c @@ -793,6 +793,8 @@ brw_postprocess_nir(nir_shader *nir, const struct brw_compiler *compiler, OPT(nir_lower_vec_to_movs); } + OPT(nir_opt_dce); + /* This is the last pass we run before we start emitting stuff. It * determines when we need to insert boolean resolves on Gen <= 5. We * run it last because it stashes data in instr->pass_flags and we don't -- 2.30.2