From: Kristian Høgsberg Kristensen <k...@bitplanet.net>
This optimizes a + b - b to just a. Modest shader-db results (BDW):
total instructions in shared programs: 7842452 -> 7841862 (-0.01%)
instructions in affected programs: 61938 -> 61348 (-0.95%)
total loops in shared programs: 2131 -> 2131 (0.00%)
helped: 263
HURT: 0
GAINED: 0
LOST: 0
but the optimization turns
gl_VertexID - gl_BaseVertexARB
into just a reference to SYSTEM_VALUE_VERTEX_ID_ZERO_BASE, which the
i965 hardware supports natively. That means we can avoid using the
internal vertex buffer for gl_BaseVertexARB in this case.
Reviewed-by: Eduardo Lima Mitev <el...@igalia.com>
Reviewed-by: Ian Romanick <ian.d.roman...@intel.com>
---
src/glsl/nir/nir_opt_algebraic.py | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/glsl/nir/nir_opt_algebraic.py
b/src/glsl/nir/nir_opt_algebraic.py
index cb715c0..1fdad3d 100644
--- a/src/glsl/nir/nir_opt_algebraic.py
+++ b/src/glsl/nir/nir_opt_algebraic.py
@@ -62,6 +62,10 @@ optimizations = [
(('iadd', ('imul', a, b), ('imul', a, c)), ('imul', a, ('iadd', b, c))),
(('fadd', ('fneg', a), a), 0.0),
(('iadd', ('ineg', a), a), 0),
+ (('iadd', ('ineg', a), ('iadd', a, b)), b),
+ (('iadd', a, ('iadd', ('ineg', a), b)), b),
+ (('fadd', ('fneg', a), ('fadd', a, b)), b),
+ (('fadd', a, ('fadd', ('fneg', a), b)), b),
(('fmul', a, 0.0), 0.0),
(('imul', a, 0), 0),
(('umul_unorm_4x8', a, 0), 0),
--
2.5.0
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