glsl2: Factor out the variable refcounting part of ir_dead_code.cpp.

src/glsl/ir_variable_refcount.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.
+ */
+
+/**
+ * \file ir_variable_refcount.cpp
+ *
+ * Provides a visitor which produces a list of variables referenced,
+ * how many times they were referenced and assigned, and whether they
+ * were defined in the scope.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_variable_refcount.h"
+#include "glsl_types.h"
+
+variable_entry *
+ir_variable_refcount_visitor::get_variable_entry(ir_variable *var)
+{
+   assert(var);
+   foreach_iter(exec_list_iterator, iter, this->variable_list) {
+      variable_entry *entry = (variable_entry *)iter.get();
+      if (entry->var == var)
+	 return entry;
+   }
+
+   variable_entry *entry = new(mem_ctx) variable_entry(var);
+   this->variable_list.push_tail(entry);
+   return entry;
+}
+
+
+ir_visitor_status
+ir_variable_refcount_visitor::visit(ir_variable *ir)
+{
+   variable_entry *entry = this->get_variable_entry(ir);
+   if (entry)
+      entry->declaration = true;
+
+   return visit_continue;
+}
+
+
+ir_visitor_status
+ir_variable_refcount_visitor::visit(ir_dereference_variable *ir)
+{
+   ir_variable *const var = ir->variable_referenced();
+   variable_entry *entry = this->get_variable_entry(var);
+
+   if (entry)
+      entry->referenced_count++;
+
+   return visit_continue;
+}
+
+
+ir_visitor_status
+ir_variable_refcount_visitor::visit_enter(ir_function_signature *ir)
+{
+   /* We don't want to descend into the function parameters and
+    * dead-code eliminate them, so just accept the body here.
+    */
+   visit_list_elements(this, &ir->body);
+   return visit_continue_with_parent;
+}
+
+
+ir_visitor_status
+ir_variable_refcount_visitor::visit_leave(ir_assignment *ir)
+{
+   variable_entry *entry;
+   entry = this->get_variable_entry(ir->lhs->variable_referenced());
+   if (entry) {
+      entry->assigned_count++;
+      if (entry->assign == NULL)
+	 entry->assign = ir;
+   }
+
+   return visit_continue;
+}