From aa6d7bc6d601c8803b136f427b8d86aa1043450c Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Thu, 7 Nov 2013 12:15:13 -0800 Subject: [PATCH] glsl: Apply the transformation "1/rsq(x) == sqrt(x)" in opt_algebraic. The comment was stale, because the lowering in question wasn't happening in lower_instructions.cpp. Presumably if the lowering ever moves there, we can plumb the lowering mask through to opt_algebraic. total instructions in shared programs: 1618696 -> 1616810 (-0.12%) instructions in affected programs: 243018 -> 241132 (-0.78%) GAINED: 0 LOST: 0 Reviewed-by: Jordan Justen --- src/glsl/opt_algebraic.cpp | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp index 448f27ed954..05a58998985 100644 --- a/src/glsl/opt_algebraic.cpp +++ b/src/glsl/opt_algebraic.cpp @@ -420,10 +420,11 @@ 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]; - /* FINISHME: We should do rcp(rsq(x)) -> sqrt(x) for some - * backends, except that some backends will have done sqrt -> - * rcp(rsq(x)) and we don't want to undo it for them. + /* 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. */ + if (op_expr[0] && op_expr[0]->operation == ir_unop_rsq) + return sqrt(op_expr[0]->operands[0]); /* As far as we know, all backends are OK with rsq. */ if (op_expr[0] && op_expr[0]->operation == ir_unop_sqrt) { -- 2.30.2