1 files changed, 153 insertions, 0 deletions
diff --git a/src/compiler/glsl/ir_variable_refcount.cpp b/src/compiler/glsl/ir_variable_refcount.cpp
new file mode 100644
index 00000000000..8306be10b9c
--- /dev/null
+++ b/src/compiler/glsl/ir_variable_refcount.cpp
@@ -0,0 +1,153 @@
+/*
+ * 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 "compiler/glsl_types.h"
+#include "util/hash_table.h"
+
+ir_variable_refcount_visitor::ir_variable_refcount_visitor()
+{
+   this->mem_ctx = ralloc_context(NULL);
+   this->ht = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
+                                      _mesa_key_pointer_equal);
+}
+
+static void
+free_entry(struct hash_entry *entry)
+{
+   ir_variable_refcount_entry *ivre = (ir_variable_refcount_entry *) entry->data;
+
+   /* Free assignment list */
+   exec_node *n;
+   while ((n = ivre->assign_list.pop_head()) != NULL) {
+      struct assignment_entry *assignment_entry =
+         exec_node_data(struct assignment_entry, n, link);
+      free(assignment_entry);
+   }
+
+   delete ivre;
+}
+
+ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
+{
+   ralloc_free(this->mem_ctx);
+   _mesa_hash_table_destroy(this->ht, free_entry);
+}
+
+// constructor
+ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable *var)
+{
+   this->var = var;
+   assigned_count = 0;
+   declaration = false;
+   referenced_count = 0;
+}
+
+
+ir_variable_refcount_entry *
+ir_variable_refcount_visitor::get_variable_entry(ir_variable *var)
+{
+   assert(var);
+
+   struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
+   if (e)
+      return (ir_variable_refcount_entry *)e->data;
+
+   ir_variable_refcount_entry *entry = new ir_variable_refcount_entry(var);
+   assert(entry->referenced_count == 0);
+   _mesa_hash_table_insert(this->ht, var, entry);
+
+   return entry;
+}
+
+
+ir_visitor_status
+ir_variable_refcount_visitor::visit(ir_variable *ir)
+{
+   ir_variable_refcount_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();
+   ir_variable_refcount_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)
+{
+   ir_variable_refcount_entry *entry;
+   entry = this->get_variable_entry(ir->lhs->variable_referenced());
+   if (entry) {
+      entry->assigned_count++;
+
+      /* Build a list for dead code optimisation. Don't add assignment if it
+       * was declared out of scope (outside the instruction stream). Also don't
+       * bother adding any more to the list if there are more references than
+       * assignments as this means the variable is used and won't be optimised
+       * out.
+       */
+      assert(entry->referenced_count >= entry->assigned_count);
+      if (entry->referenced_count == entry->assigned_count) {
+         struct assignment_entry *assignment_entry =
+            (struct assignment_entry *)calloc(1, sizeof(*assignment_entry));
+         assignment_entry->assign = ir;
+         entry->assign_list.push_head(&assignment_entry->link);
+      }
+   }
+
+   return visit_continue;
+}