svn merge ^/branches/released .

1 files changed, 187 insertions, 0 deletions

diff --git a/mesalib/src/glsl/loop_unroll.cpp b/mesalib/src/glsl/loop_unroll.cpp
new file mode 100644
index 000000000..90797bde3
--- /dev/null
+++ b/mesalib/src/glsl/loop_unroll.cpp
@@ -0,0 +1,187 @@
+/*
+ * 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, unsigned max_iterations)
+   {
+      this->state = state;
+      this->progress = false;
+      this->max_iterations = max_iterations;
+   }
+
+   virtual ir_visitor_status visit_leave(ir_loop *ir);
+
+   loop_state *state;
+
+   bool progress;
+   unsigned max_iterations;
+};
+
+
+ir_visitor_status
+loop_unroll_visitor::visit_leave(ir_loop *ir)
+{
+   loop_variable_state *const ls = this->state->get(ir);
+   int iterations;
+
+   /* 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;
+   }
+
+   iterations = ls->max_iterations;
+
+   /* Don't try to unroll loops where the number of iterations is not known
+    * at compile-time.
+    */
+   if (iterations < 0)
+      return visit_continue;
+
+   /* Don't try to unroll loops that have zillions of iterations either.
+    */
+   if (iterations > max_iterations)
+      return visit_continue;
+
+   if (ls->num_loop_jumps > 1)
+      return visit_continue;
+   else if (ls->num_loop_jumps) {
+      /* recognize loops in the form produced by ir_lower_jumps */
+      ir_instruction *last_ir =
+	 ((ir_instruction*)ir->body_instructions.get_tail());
+
+      assert(last_ir != NULL);
+
+      ir_if *last_if = last_ir->as_if();
+      if (last_if) {
+	 bool continue_from_then_branch;
+
+	 /* Determine which if-statement branch, if any, ends with a break.
+	  * The branch that did *not* have the break will get a temporary
+	  * continue inserted in each iteration of the loop unroll.
+	  *
+	  * Note that since ls->num_loop_jumps is <= 1, it is impossible for
+	  * both branches to end with a break.
+	  */
+	 ir_instruction *last =
+	    (ir_instruction *) last_if->then_instructions.get_tail();
+
+	 if (last && last->ir_type == ir_type_loop_jump
+	     && ((ir_loop_jump*) last)->is_break()) {
+	    continue_from_then_branch = false;
+	 } else {
+	    last = (ir_instruction *) last_if->then_instructions.get_tail();
+
+	    if (last && last->ir_type == ir_type_loop_jump
+		&& ((ir_loop_jump*) last)->is_break())
+	       continue_from_then_branch = true;
+	    else
+	       /* Bail out if neither if-statement branch ends with a break.
+		*/
+	       return visit_continue;
+	 }
+
+	 /* Remove the break from the if-statement.
+	  */
+	 last->remove();
+
+         void *const mem_ctx = talloc_parent(ir);
+         ir_instruction *ir_to_replace = ir;
+
+         for (int i = 0; i < iterations; i++) {
+            exec_list copy_list;
+
+            copy_list.make_empty();
+            clone_ir_list(mem_ctx, &copy_list, &ir->body_instructions);
+
+            last_if = ((ir_instruction*)copy_list.get_tail())->as_if();
+            assert(last_if);
+
+            ir_to_replace->insert_before(&copy_list);
+            ir_to_replace->remove();
+
+            /* placeholder that will be removed in the next iteration */
+            ir_to_replace =
+	       new(mem_ctx) ir_loop_jump(ir_loop_jump::jump_continue);
+
+            exec_list *const list = (continue_from_then_branch)
+	       ? &last_if->then_instructions : &last_if->else_instructions;
+
+            list->push_tail(ir_to_replace);
+         }
+
+         ir_to_replace->remove();
+
+         this->progress = true;
+         return visit_continue;
+      } else if (last_ir->ir_type == ir_type_loop_jump
+		 && ((ir_loop_jump *)last_ir)->is_break()) {
+	 /* If the only loop-jump is a break at the end of the loop, the loop
+	  * will execute exactly once.  Remove the break, set the iteration
+	  * count, and fall through to the normal unroller.
+	  */
+         last_ir->remove();
+	 iterations = 1;
+
+	 this->progress = true;
+      } else
+         return visit_continue;
+   }
+
+   void *const mem_ctx = talloc_parent(ir);
+
+   for (int i = 0; i < 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, unsigned max_iterations)
+{
+   loop_unroll_visitor v(ls, max_iterations);
+
+   v.run(instructions);
+
+   return v.progress;
+}