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

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 44577c48573acdbc8a708e6613f367507e9eafc5
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=44577c48573acdbc8a708e6613f367507e9eafc5

Author: Eric Anholt <eric at anholt.net>
Date:   Sat Jan 18 11:00:51 2014 -0800

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 at gmail.com>

---

 src/glsl/opt_algebraic.cpp |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 953b03c..392051f 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;