glsl2: Add module to perform simple loop unrolling

1 files changed, 100 insertions, 0 deletions

diff --git a/src/glsl/loop_unroll.cpp b/src/glsl/loop_unroll.cpp
new file mode 100644
index 0000000000..e204251e9c
--- /dev/null
+++ b/src/glsl/loop_unroll.cpp
@@ -0,0 +1,100 @@
+/*
+ * 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.
+ */
+
+#include "glsl_types.h"
+#include "loop_analysis.h"
+#include "ir_hierarchical_visitor.h"
+
+class loop_unroll_visitor : public ir_hierarchical_visitor {
+public:
+   loop_unroll_visitor(loop_state *state)
+   {
+      this->state = state;
+      this->progress = false;
+   }
+
+   virtual ir_visitor_status visit_leave(ir_loop *ir);
+
+   loop_state *state;
+
+   bool progress;
+};
+
+
+ir_visitor_status
+loop_unroll_visitor::visit_leave(ir_loop *ir)
+{
+   loop_variable_state *const ls = this->state->get(ir);
+
+   /* If we've entered a loop that hasn't been analyzed, something really,
+    * really bad has happened.
+    */
+   if (ls == NULL) {
+      assert(ls != NULL);
+      return visit_continue;
+   }
+
+   /* Don't try to unroll loops where the number of iterations is not known
+    * at compile-time.
+    */
+   if (ls->max_iterations < 0)
+      return visit_continue;
+
+   /* Don't try to unroll loops that have zillions of iterations either.
+    */
+   if (ls->max_iterations > 32)
+      return visit_continue;
+
+   if (ls->num_loop_jumps > 0)
+      return visit_continue;
+
+   void *const mem_ctx = talloc_parent(ir);
+
+   for (int i = 0; i < ls->max_iterations; i++) {
+      exec_list copy_list;
+
+      copy_list.make_empty();
+      clone_ir_list(mem_ctx, &copy_list, &ir->body_instructions);
+
+      ir->insert_before(&copy_list);
+   }
+
+   /* The loop has been replaced by the unrolled copies.  Remove the original
+    * loop from the IR sequence.
+    */
+   ir->remove();
+
+   this->progress = true;
+   return visit_continue;
+}
+
+
+bool
+unroll_loops(exec_list *instructions, loop_state *ls)
+{
+   loop_unroll_visitor v(ls);
+
+   v.run(instructions);
+
+   return v.progress;
+}