Mesa (master): nir/algebraic: Optimize x2b(xneg(a)) -> a

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Module: Mesa
Branch: master
Commit: 4bb1a34727f52ecd4a8f00725d740ae2047cb1dc
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4bb1a34727f52ecd4a8f00725d740ae2047cb1dc

Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Thu Dec  6 13:02:01 2018 -0600

nir/algebraic: Optimize x2b(xneg(a)) -> a

Shader-db results on Kaby Lake:

    total instructions in shared programs: 15072525 -> 15072525 (0.00%)
    instructions in affected programs: 0 -> 0
    helped: 0
    HURT: 0

This helps prevent regressions in later commits.

Reviewed-by: Eric Anholt <eric at anholt.net>
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Tested-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

---

 src/compiler/nir/nir_opt_algebraic.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
index 28e8a96d4d..ea24094a92 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -85,6 +85,8 @@ optimizations = [
    (('fabs', ('u2f', a)), ('u2f', a)),
    (('iabs', ('iabs', a)), ('iabs', a)),
    (('iabs', ('ineg', a)), ('iabs', a)),
+   (('f2b', ('fneg', a)), ('f2b', a)),
+   (('i2b', ('ineg', a)), ('i2b', a)),
    (('~fadd', a, 0.0), a),
    (('iadd', a, 0), a),
    (('usadd_4x8', a, 0), a),