Mesa (master): glsl: Optimize ~~x into x.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 2c2aa353366c610382273bea10656e6d6960ce3b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2c2aa353366c610382273bea10656e6d6960ce3b

Author: Eric Anholt <eric at anholt.net>
Date:   Sat Jan 18 10:36:28 2014 -0800

glsl: Optimize ~~x into x.

v2: Fix pasteo of an extra abs being inserted (caught by many).  Rewrite
    to drop the silly switch statement.

Reviewed-by: Matt Turner <mattst88 at gmail.com> (v1)

---

 src/glsl/opt_algebraic.cpp |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index d1f6435..681973d 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -218,6 +218,11 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
       this->mem_ctx = ralloc_parent(ir);
 
    switch (ir->operation) {
+   case ir_unop_bit_not:
+      if (op_expr[0] && op_expr[0]->operation == ir_unop_bit_not)
+         return op_expr[0]->operands[0];
+      break;
+
    case ir_unop_abs:
       if (op_expr[0] == NULL)
 	 break;