Lots of shaders divide by exp2(...) which we turn into a multiplication
by the reciprocal. We can avoid the reciprocal by simply negating exp2's
argument.
total instructions in shared programs: 5947154 -> 5946695 (-0.01%)
instructions in affected programs: 118661 -> 118202 (-0.39%)
helped: 380
---
src/glsl/opt_algebraic.cpp | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index c6f4a9c..616ed37 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -747,6 +747,12 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
if (op_expr[0] && op_expr[0]->operation == ir_unop_rcp)
return op_expr[0]->operands[0];
+ if (op_expr[0] && (op_expr[0]->operation == ir_unop_exp2 ||
+ op_expr[0]->operation == ir_unop_exp)) {
+ return new(mem_ctx) ir_expression(op_expr[0]->operation, ir->type,
+ neg(op_expr[0]->operands[0]));
+ }
+
/* While ir_to_mesa.cpp will lower sqrt(x) to rcp(rsq(x)), it does so at
* its IR level, so we can always apply this transformation.
*/
--
2.0.5
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