When analyzing output for glsl-mat-from-int-ctor-03 piglit test, found
that the following piece of generated asm code:
mov(8) g19<1>.xyzF g6<4,4,1>.xyzzD { align16 1Q };
dp4(8) g115<1>.wF g4<4,4,1>F g2.4<0,4,1>F { align16
NoDDChk 1Q };
cmp.nz.f0(8) null<1>F g11<4,4,1>.xyzzF g19<4,4,1>.xyzzF { align16 1Q
switch };
cmp.nz.f0(8) null<1>D g7<4,4,1>D 0D { align16 1Q
switch };
(+f0.any4h) mov(8) g21<1>.xUD 0xffffffffUD { align16 1Q };
can be further optimized if we remove the former cmp instruction, as the
output is overwritten by the second one (a clearly dead-code).
The reason why this was not optimized is in vec4_visitor::run()
(brw_vec4.cpp file). If opt_vector_float() success, then we apply
several optimizations once, including a dead-code eliminate.
But turns out that running this DCE optimization leds to the code above,
and as we don't run again the DCE (we don't run them in a loop), the
code remains as above.
So this commit run all those optimizations in a loop. More strictly,
instead of running them in a separated loop, it runs them in the
previous loop, with all the other optimizations.
When testing against the improvement obtained against shader-db, we
don't get any improvement (nor any loose). But testing also against the
non-free shaders in shader-db, we get the following improvement:
total instructions in shared programs: 6819828 -> 6819468 (-0.01%)
instructions in affected programs: 30516 -> 30156 (-1.18%)
total loops in shared programs: 1971 -> 1971 (0.00%)
helped: 154
HURT: 0
GAINED: 0
LOST: 0
Signed-off-by: Juan A. Suarez Romero <jasua...@igalia.com>
---
src/mesa/drivers/dri/i965/brw_vec4.cpp | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp
b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 9a79d67..39e525d 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -1846,19 +1846,15 @@ vec4_visitor::run()
OPT(opt_copy_propagation);
OPT(opt_cmod_propagation);
OPT(opt_cse);
- OPT(opt_algebraic);
OPT(opt_register_coalesce);
OPT(eliminate_find_live_channel);
- } while (progress);
-
- pass_num = 0;
-
- if (OPT(opt_vector_float)) {
+ OPT(opt_algebraic);
+ OPT(opt_vector_float);
OPT(opt_cse);
OPT(opt_copy_propagation, false);
OPT(opt_copy_propagation, true);
OPT(dead_code_eliminate);
- }
+ } while (progress);
if (failed)
return false;
--
2.5.0
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