Optimize conditional branches that have same true/false targets.

runtime/vm/intermediate_language.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 1367 matching lines @@
     return const_cast<BlockEntryInstr*>(this);
   }
 
   // Helper to mutate the graph during inlining. This block should be
   // replaced with new_block as a predecessor of all of this block's
   // successors.
   void ReplaceAsPredecessorWith(BlockEntryInstr* new_block);
 
   void set_block_id(intptr_t block_id) { block_id_ = block_id; }
 
+  // For all instruction in this block: Remove all inputs (including in the
+  // environment) from their definition's use lists for all instructions.
+  void ClearAllInstructions();
+
  protected:
   BlockEntryInstr(intptr_t block_id, intptr_t try_index)
       : block_id_(block_id),
         try_index_(try_index),
         preorder_number_(-1),
         postorder_number_(-1),
         dominator_(NULL),
         dominated_blocks_(1),
         last_instruction_(NULL),
         parallel_move_(NULL),
@@ skipping 6518 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_