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authorIan Romanick <ian.d.romanick@intel.com>2019-08-12 18:44:56 -0700
committerDylan Baker <dylan@pnwbakers.com>2019-09-04 11:56:59 -0700
commit6934bc4f0800ab7154c6a2efa541f073cda7a6b9 (patch)
tree79707b62a7ffcbc801980f57396abbb7d88e6f48
parent6aa7a103709542f36e1e3678abf047001b4f1d5f (diff)
nir/range-analysis: Handle constants in nir_op_mov just like nir_op_bcsel
I discovered this while looking at a shader that was hurt by some other work I'm doing. When I examined the changes, I was confused that one instance of a comparison that was used in a discard_if was (incorrectly) eliminated, while another instance used by a bcsel was (correctly) not eliminated. I had to use NIR_PRINT=true to see exactly where things when wrong. A bunch of shaders in Goat Simulator, Dungeon Defenders, Sanctum 2, and Strike Suit Zero were impacted. Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com> Fixes: 405de7ccb6c ("nir/range-analysis: Rudimentary value range analysis pass") All Intel platforms had similar results. (Ice Lake shown) total instructions in shared programs: 16280659 -> 16281075 (<.01%) instructions in affected programs: 21042 -> 21458 (1.98%) helped: 0 HURT: 136 HURT stats (abs) min: 1 max: 9 x̄: 3.06 x̃: 3 HURT stats (rel) min: 1.16% max: 6.12% x̄: 2.23% x̃: 2.03% 95% mean confidence interval for instructions value: 2.93 3.19 95% mean confidence interval for instructions %-change: 2.08% 2.37% Instructions are HURT. total cycles in shared programs: 367168270 -> 367170313 (<.01%) cycles in affected programs: 172020 -> 174063 (1.19%) helped: 14 HURT: 111 helped stats (abs) min: 2 max: 80 x̄: 21.21 x̃: 9 helped stats (rel) min: 0.10% max: 4.47% x̄: 1.35% x̃: 0.79% HURT stats (abs) min: 2 max: 584 x̄: 21.08 x̃: 5 HURT stats (rel) min: 0.12% max: 17.28% x̄: 1.55% x̃: 0.40% 95% mean confidence interval for cycles value: 5.41 27.28 95% mean confidence interval for cycles %-change: 0.64% 1.81% Cycles are HURT. (cherry picked from commit 7dba7df5e577b94e009848a2ca3e0b0a41629fe9)
-rw-r--r--src/compiler/nir/nir_range_analysis.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/src/compiler/nir/nir_range_analysis.c b/src/compiler/nir/nir_range_analysis.c
index b7a2f20d473..6dfaea167ac 100644
--- a/src/compiler/nir/nir_range_analysis.c
+++ b/src/compiler/nir/nir_range_analysis.c
@@ -610,9 +610,16 @@ analyze_expression(const nir_alu_instr *instr, unsigned src,
r = (struct ssa_result_range){analyze_expression(alu, 0, ht).range, false};
break;
- case nir_op_mov:
- r = analyze_expression(alu, 0, ht);
+ case nir_op_mov: {
+ const struct ssa_result_range left = analyze_expression(alu, 0, ht);
+
+ /* See commentary in nir_op_bcsel for the reasons this is necessary. */
+ if (nir_src_is_const(alu->src[0].src) && left.range != eq_zero)
+ return (struct ssa_result_range){unknown, false};
+
+ r = left;
break;
+ }
case nir_op_fneg:
r = analyze_expression(alu, 0, ht);