diff options
| author | Matt Turner <[email protected]> | 2015-02-10 12:31:37 -0800 |
|---|---|---|
| committer | Matt Turner <[email protected]> | 2015-02-10 17:48:44 -0800 |
| commit | ea0f0eb6c0a8b20bcce50c63170df94892a51142 (patch) | |
| tree | bc45fafd47f685fdc1774b671f27a196dbade54f | |
| parent | a9065cef4879509c3dc96a5195f785647576f409 (diff) | |
glsl: Optimize 1/exp(x) into exp(-x).
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
Reviewed-by: Jason Ekstrand <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
| -rw-r--r-- | src/glsl/opt_algebraic.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp index c6f4a9c786d..616ed37b952 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. */ |