From 4f189b3bf57a6500953dac49105f160af5fa6468 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Marek=20Ol=C5=A1=C3=A1k?= Date: Tue, 31 Aug 2010 05:38:50 +0200 Subject: [PATCH] ir_to_mesa: use RSQ+MUL instead of RSQ+RCP for SQRT sqrt(x) = 1/rsq(x) = x*rsq(x) This optimization already was in the old GLSL compiler. Acked on irc by Eric Anholt. --- src/mesa/program/ir_to_mesa.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp index af6d7345a54..516c991855d 100644 --- a/src/mesa/program/ir_to_mesa.cpp +++ b/src/mesa/program/ir_to_mesa.cpp @@ -880,8 +880,9 @@ ir_to_mesa_visitor::visit(ir_expression *ir) break; case ir_unop_sqrt: + /* sqrt(x) = x * rsq(x). */ ir_to_mesa_emit_scalar_op1(ir, OPCODE_RSQ, result_dst, op[0]); - ir_to_mesa_emit_scalar_op1(ir, OPCODE_RCP, result_dst, result_src); + ir_to_mesa_emit_op2(ir, OPCODE_MUL, result_dst, result_src, op[0]); /* For incoming channels < 0, set the result to 0. */ ir_to_mesa_emit_op3(ir, OPCODE_CMP, result_dst, op[0], src_reg_for_float(0.0), result_src); -- 2.30.2