1 files changed, 84 insertions, 0 deletions
diff --git a/src/glsl/opt_if_simplification.cpp b/src/glsl/opt_if_simplification.cpp
new file mode 100644
index 00000000000..618bacfecf1
--- /dev/null
+++ b/src/glsl/opt_if_simplification.cpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file opt_if_simplification.cpp
+ *
+ * Moves constant branches of if statements out to the surrounding
+ * instruction stream.
+ */
+
+#include "ir.h"
+
+class ir_if_simplification_visitor : public ir_hierarchical_visitor {
+public:
+   ir_if_simplification_visitor()
+   {
+      this->made_progress = false;
+   }
+
+   ir_visitor_status visit_leave(ir_if *);
+
+   bool made_progress;
+};
+
+bool
+do_if_simplification(exec_list *instructions)
+{
+   ir_if_simplification_visitor v;
+
+   v.run(instructions);
+   return v.made_progress;
+}
+
+
+ir_visitor_status
+ir_if_simplification_visitor::visit_leave(ir_if *ir)
+{
+   /* FINISHME: Ideally there would be a way to note that the condition results
+    * FINISHME: in a constant before processing both of the other subtrees.
+    * FINISHME: This can probably be done with some flags, but it would take
+    * FINISHME: some work to get right.
+    */
+   ir_constant *condition_constant = ir->condition->constant_expression_value();
+   if (condition_constant) {
+      /* Move the contents of the one branch of the conditional
+       * that matters out.
+       */
+      if (condition_constant->value.b[0]) {
+	 foreach_iter(exec_list_iterator, then_iter, ir->then_instructions) {
+	    ir_instruction *then_ir = (ir_instruction *)then_iter.get();
+	    ir->insert_before(then_ir);
+	 }
+      } else {
+	 foreach_iter(exec_list_iterator, else_iter, ir->else_instructions) {
+	    ir_instruction *else_ir = (ir_instruction *)else_iter.get();
+	    ir->insert_before(else_ir);
+	 }
+      }
+      ir->remove();
+      this->made_progress = true;
+   }
+
+   return visit_continue;
+}