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authorKenneth Graunke <kenneth@whitecape.org>2013-10-19 21:27:37 -0700
committerKenneth Graunke <kenneth@whitecape.org>2013-10-21 23:31:15 -0700
commit43b05b8fac68784bc8d61851125bd49783e5ebd0 (patch)
tree40cdf46cdee35481e727fa5ceb74afe3393def4d
parentc4de86fd26520f1bc5650c1f08a05fa0845dd881 (diff)
i965: Only emit interpolation setup if there are actual FS inputs.
Dead code elimination would get rid of the extra instructions, but skipping this saves iterations through the optimization loop. From shader-db: N Min Max Median Avg Stddev x 14672 3 16 3 3.1334515 0.59904168 + 14672 1 16 3 2.8955153 0.77732963 Difference at 95.0% confidence -0.237936 +/- 0.0158798 -7.59342% +/- 0.506783% (Student's t, pooled s = 0.693935) Embarassingly, the classic shadow mapping shader: void main() { } used to require three iterations through the optimization loop. With this patch, it only requires one (which makes no progress). Signed-off-by: Kenneth Graunke <kenneth@whitecape.org> Reviewed-by: Matt Turner <mattst88@gmail.com> Reviewed-by: Eric Anholt <eric@anholt.net>
-rw-r--r--src/mesa/drivers/dri/i965/brw_fs.cpp10
1 files changed, 6 insertions, 4 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 65a4b66c6b9..a3268fb73bf 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -3025,10 +3025,12 @@ fs_visitor::run()
emit_shader_time_begin();
calculate_urb_setup();
- if (brw->gen < 6)
- emit_interpolation_setup_gen4();
- else
- emit_interpolation_setup_gen6();
+ if (fp->Base.InputsRead > 0) {
+ if (brw->gen < 6)
+ emit_interpolation_setup_gen4();
+ else
+ emit_interpolation_setup_gen6();
+ }
/* We handle discards by keeping track of the still-live pixels in f0.1.
* Initialize it with the dispatched pixels.