Mesa (master): glsl: Optimize pow(x, 2) into x * x.

[Matt Turner]

Module: Mesa
Branch: master
Commit: 6cbc64c3cb416fadad6e80042e24cd1e1b682897
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6cbc64c3cb416fadad6e80042e24cd1e1b682897

Author: Matt Turner <mattst88 at gmail.com>
Date:   Fri Feb 28 13:33:19 2014 -0800

glsl: Optimize pow(x, 2) into x * x.

Cuts two instructions out of SynMark's Gl32VSInstancing benchmark.

Reviewed-by: Eric Anholt <eric at anholt.net>

---

 src/glsl/opt_algebraic.cpp |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 5c49a78..8494bd9 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -528,6 +528,14 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
       if (is_vec_two(op_const[0]))
          return expr(ir_unop_exp2, ir->operands[1]);
 
+      if (is_vec_two(op_const[1])) {
+         ir_variable *x = new(ir) ir_variable(ir->operands[1]->type, "x",
+                                              ir_var_temporary);
+         base_ir->insert_before(x);
+         base_ir->insert_before(assign(x, ir->operands[0]));
+         return mul(x, x);
+      }
+
       break;
 
    case ir_unop_rcp: