From: Eric Anholt <eric@anholt.net>
Date: Sat, 18 Jan 2014 19:00:51 +0000 (-0800)
Subject: glsl: Optimize lrp(x, x, coefficient) --> x.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=44577c48573acdbc8a708e6613f367507e9eafc5;p=mesa.git

glsl: Optimize lrp(x, x, coefficient) --> x.

total instructions in shared programs: 1627754 -> 1624534 (-0.20%)
instructions in affected programs:     45748 -> 42528 (-7.04%)
GAINED:                                3
LOST:                                  0

(serious sam, humus domino demo)

Reviewed-by: Matt Turner <mattst88@gmail.com>
---

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 953b03c2943..392051f4f05 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -553,6 +553,8 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
          return ir->operands[0];
       } else if (is_vec_one(op_const[2])) {
          return ir->operands[1];
+      } else if (ir->operands[0]->equals(ir->operands[1])) {
+         return ir->operands[0];
       }
       break;