Mesa (master): glsl: Optimize pow(x, 1) -> x.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: d72956790fed5f62b8eea5938ed432544530f7bd
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d72956790fed5f62b8eea5938ed432544530f7bd

Author: Eric Anholt <eric at anholt.net>
Date:   Sat Jan 18 10:57:29 2014 -0800

glsl: Optimize pow(x, 1) -> x.

total instructions in shared programs: 1627826 -> 1627754 (-0.00%)
instructions in affected programs:     6640 -> 6568 (-1.08%)
GAINED:                                0
LOST:                                  0

(HoN and savage2)

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

---

 src/glsl/opt_algebraic.cpp |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 1e71581..953b03c 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -520,6 +520,10 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
       if (is_vec_one(op_const[0]))
          return op_const[0];
 
+      /* x^1 == x */
+      if (is_vec_one(op_const[1]))
+         return ir->operands[0];
+
       /* pow(2,x) == exp2(x) */
       if (is_vec_two(op_const[0]))
          return expr(ir_unop_exp2, ir->operands[1]);