Mesa (master): glsl: Optimize log(exp(x)) and exp(log(x)) into x.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 6d7c123d6ce46e71ef22e431b76e972b9be1a157
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6d7c123d6ce46e71ef22e431b76e972b9be1a157

Author: Eric Anholt <eric at anholt.net>
Date:   Sat Jan 18 10:47:19 2014 -0800

glsl: Optimize log(exp(x)) and exp(log(x)) into x.

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

---

 src/glsl/opt_algebraic.cpp |   36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 681973d..1e71581 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -245,6 +245,42 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
       }
       break;
 
+   case ir_unop_exp:
+      if (op_expr[0] == NULL)
+	 break;
+
+      if (op_expr[0]->operation == ir_unop_log) {
+         return op_expr[0]->operands[0];
+      }
+      break;
+
+   case ir_unop_log:
+      if (op_expr[0] == NULL)
+	 break;
+
+      if (op_expr[0]->operation == ir_unop_exp) {
+         return op_expr[0]->operands[0];
+      }
+      break;
+
+   case ir_unop_exp2:
+      if (op_expr[0] == NULL)
+	 break;
+
+      if (op_expr[0]->operation == ir_unop_log2) {
+         return op_expr[0]->operands[0];
+      }
+      break;
+
+   case ir_unop_log2:
+      if (op_expr[0] == NULL)
+	 break;
+
+      if (op_expr[0]->operation == ir_unop_exp2) {
+         return op_expr[0]->operands[0];
+      }
+      break;
+
    case ir_unop_logic_not: {
       enum ir_expression_operation new_op = ir_unop_logic_not;