[Mesa-dev] [PATCH 2/5] glsl: Apply the transformation "(a || a) -> a" in opt_algebraic.

[Eric Anholt]

total instructions in shared programs: 1732385 -> 1732373 (-0.00%)
instructions in affected programs:     416 -> 404 (-2.88%)
GAINED:                                0
LOST:                                  0

(That's 4 already-short fragment shaders in dota2)
---
 src/glsl/opt_algebraic.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index a07e153..3da27e5 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -388,7 +388,6 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
       break;
 
    case ir_binop_logic_or:
-      /* FINISHME: Also simplify (a || a) to (a). */
       if (is_vec_zero(op_const[0])) {
 	 return ir->operands[1];
       } else if (is_vec_zero(op_const[1])) {
@@ -407,6 +406,9 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
           */
          return logic_not(logic_and(op_expr[0]->operands[0],
                                     op_expr[1]->operands[0]));
+      } else if (ir->operands[0]->equals(ir->operands[1])) {
+         /* (a || a) == a */
+         return ir->operands[0];
       }
       break;
 
-- 
1.8.4.rc3