Refactor branch instructions to enable further optimizations.

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_optimizer.h"
 
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/hash_map.h"
 #include "vm/il_printer.h"
@@ skipping 734 matching lines @@
     comp->set_receiver_class_id(kNumberCid);
   }
 }
 
 
 void FlowGraphOptimizer::VisitBind(BindInstr* instr) {
   instr->computation()->Accept(this, instr);
 }
 
 
+void FlowGraphOptimizer::VisitBranch(BranchInstr* instr) {
+  instr->computation()->Accept(this, NULL);
+}
+
+
 void FlowGraphTypePropagator::VisitAssertAssignable(AssertAssignableComp* comp,
                                                     BindInstr* instr) {
   if (FLAG_eliminate_type_checks &&
       !comp->is_eliminated() &&
       comp->value()->CompileTypeIsMoreSpecificThan(comp->dst_type())) {
     // TODO(regis): Remove is_eliminated_ field and support.
     comp->eliminate();
 
     UseVal* use = comp->value()->AsUse();
     ASSERT(use != NULL);
@@ skipping 299 matching lines @@
       DirectChainedHashMap<BindInstr*> child_map(*map);  // Copy map.
       OptimizeRecursive(child, &child_map);
     } else {
       OptimizeRecursive(child, map);  // Reuse map for the last child.
     }
   }
 }
 
 
 }  // namespace dart