These will optimize any tree of a commutative and associative operation
that contains more than one constant to have only one constant in the
end. For example, it will optimize
((4 * a) * b) * (5 * c)
into
20 * ((a * b) * c)
Note that when we port Matt's tree balancing pass, we'll have to think
carefully to make sure they don't fight.
Signed-off-by: Connor Abbott <cwabbo...@gmail.com>
---
src/glsl/nir/nir_opt_algebraic.py | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/src/glsl/nir/nir_opt_algebraic.py
b/src/glsl/nir/nir_opt_algebraic.py
index a5fe19a..f4466b4 100644
--- a/src/glsl/nir/nir_opt_algebraic.py
+++ b/src/glsl/nir/nir_opt_algebraic.py
@@ -128,6 +128,16 @@ optimizations = [
# next round of opt_algebraic, get picked up by one of the above two.
(('bcsel', '#a', b, c), ('bcsel', ('ine', 'a', 0), b, c)),
+ # constant reassociation
+ # the idea is that we make sure each expression tree always ends with
+ # "constant thing plus tree of non-constant things'
+ (('!a@associative,commutative', '#a', ('!a', '#b', 'c')),
+ ('!a', ('!a', 'a', 'b'), 'c')),
+ (('!a@associative,commutative', ('!a', '#a', 'b'), ('!a', '#c', 'd')),
+ ('!a', ('!a', 'a', 'c'), ('!a', 'b', 'd'))),
+ (('!a@associative,commutative', ('!a', '#a', 'b'), 'c'),
+ ('!a', 'a', ('!a', 'b', 'c'))),
+
# This one may not be exact
(('feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
]
--
2.1.0
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