xserver and mesa git update 28-12-2010

1 files changed, 229 insertions, 0 deletions

diff --git a/mesalib/src/glsl/opt_dead_code_local.cpp b/mesalib/src/glsl/opt_dead_code_local.cpp
new file mode 100644
index 000000000..182eccac2
--- /dev/null
+++ b/mesalib/src/glsl/opt_dead_code_local.cpp
@@ -0,0 +1,229 @@
+/*

+ * 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_dead_code_local.cpp

+ *

+ * Eliminates local dead assignments from the code.

+ *

+ * This operates on basic blocks, tracking assignments and finding if

+ * they're used before the variable is completely reassigned.

+ *

+ * Compare this to ir_dead_code.cpp, which operates globally looking

+ * for assignments to variables that are never read.

+ */

+

+#include "ir.h"

+#include "ir_basic_block.h"

+#include "ir_optimization.h"

+#include "glsl_types.h"

+

+static bool debug = false;

+

+class assignment_entry : public exec_node

+{

+public:

+   assignment_entry(ir_variable *lhs, ir_instruction *ir)

+   {

+      assert(lhs);

+      assert(ir);

+      this->lhs = lhs;

+      this->ir = ir;

+   }

+

+   ir_variable *lhs;

+   ir_instruction *ir;

+};

+

+class kill_for_derefs_visitor : public ir_hierarchical_visitor {

+public:

+   kill_for_derefs_visitor(exec_list *assignments)

+   {

+      this->assignments = assignments;

+   }

+

+   virtual ir_visitor_status visit(ir_dereference_variable *ir)

+   {

+      ir_variable *const var = ir->variable_referenced();

+

+      foreach_iter(exec_list_iterator, iter, *this->assignments) {

+	 assignment_entry *entry = (assignment_entry *)iter.get();

+

+	 if (entry->lhs == var) {

+	    if (debug)

+	       printf("kill %s\n", entry->lhs->name);

+	    entry->remove();

+	 }

+      }

+

+      return visit_continue;

+   }

+

+private:

+   exec_list *assignments;

+};

+

+class array_index_visit : public ir_hierarchical_visitor {

+public:

+   array_index_visit(ir_hierarchical_visitor *v)

+   {

+      this->visitor = v;

+   }

+

+   virtual ir_visitor_status visit_enter(class ir_dereference_array *ir)

+   {

+      ir->array_index->accept(visitor);

+      return visit_continue;

+   }

+

+   static void run(ir_instruction *ir, ir_hierarchical_visitor *v)

+   {

+      array_index_visit top_visit(v);

+      ir->accept(& top_visit);

+   }

+

+   ir_hierarchical_visitor *visitor;

+};

+

+

+/**

+ * Adds an entry to the available copy list if it's a plain assignment

+ * of a variable to a variable.

+ */

+static bool

+process_assignment(void *ctx, ir_assignment *ir, exec_list *assignments)

+{

+   ir_variable *var = NULL;

+   bool progress = false;

+   kill_for_derefs_visitor v(assignments);

+

+   /* Kill assignment entries for things used to produce this assignment. */

+   ir->rhs->accept(&v);

+   if (ir->condition) {

+      ir->condition->accept(&v);

+   }

+

+   /* Kill assignment enties used as array indices.

+    */

+   array_index_visit::run(ir->lhs, &v);

+   var = ir->lhs->variable_referenced();

+   assert(var);

+

+   bool always_assign = true;

+   if (ir->condition) {

+      ir_constant *condition = ir->condition->as_constant();

+      if (!condition || !condition->value.b[0])

+	 always_assign = false;

+   }

+

+   /* Now, check if we did a whole-variable assignment. */

+   if (always_assign && (ir->whole_variable_written() != NULL)) {

+      /* We did a whole-variable assignment.  So, any instruction in

+       * the assignment list with the same LHS is dead.

+       */

+      if (debug)

+	 printf("looking for %s to remove\n", var->name);

+      foreach_iter(exec_list_iterator, iter, *assignments) {

+	 assignment_entry *entry = (assignment_entry *)iter.get();

+

+	 if (entry->lhs == var) {

+	    if (debug)

+	       printf("removing %s\n", var->name);

+	    entry->ir->remove();

+	    entry->remove();

+	    progress = true;

+	 }

+      }

+   }

+

+   /* Add this instruction to the assignment list available to be removed.

+    * But not if the assignment has other side effects.

+    */

+   if (ir_has_call(ir))

+      return progress;

+

+   assignment_entry *entry = new(ctx) assignment_entry(var, ir);

+   assignments->push_tail(entry);

+

+   if (debug) {

+      printf("add %s\n", var->name);

+

+      printf("current entries\n");

+      foreach_iter(exec_list_iterator, iter, *assignments) {

+	 assignment_entry *entry = (assignment_entry *)iter.get();

+

+	 printf("    %s\n", entry->lhs->name);

+      }

+   }

+

+   return progress;

+}

+

+static void

+dead_code_local_basic_block(ir_instruction *first,

+			     ir_instruction *last,

+			     void *data)

+{

+   ir_instruction *ir, *ir_next;

+   /* List of avaialble_copy */

+   exec_list assignments;

+   bool *out_progress = (bool *)data;

+   bool progress = false;

+

+   void *ctx = talloc_new(NULL);

+   /* Safe looping, since process_assignment */

+   for (ir = first, ir_next = (ir_instruction *)first->next;;

+	ir = ir_next, ir_next = (ir_instruction *)ir->next) {

+      ir_assignment *ir_assign = ir->as_assignment();

+

+      if (debug) {

+	 ir->print();

+	 printf("\n");

+      }

+

+      if (ir_assign) {

+	 progress = process_assignment(ctx, ir_assign, &assignments) || progress;

+      } else {

+	 kill_for_derefs_visitor kill(&assignments);

+	 ir->accept(&kill);

+      }

+

+      if (ir == last)

+	 break;

+   }

+   *out_progress = progress;

+   talloc_free(ctx);

+}

+

+/**

+ * Does a copy propagation pass on the code present in the instruction stream.

+ */

+bool

+do_dead_code_local(exec_list *instructions)

+{

+   bool progress = false;

+

+   call_for_basic_blocks(instructions, dead_code_local_basic_block, &progress);

+

+   return progress;

+}