[turbofan] reduce ResolveControlFlow overhead.

src/compiler/register-allocator.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_REGISTER_ALLOCATOR_H_
 #define V8_REGISTER_ALLOCATOR_H_
 
 #include "src/compiler/instruction.h"
 #include "src/ostreams.h"
 #include "src/register-configuration.h"
@@ skipping 554 matching lines @@
 
 #if DEBUG
   int debug_virt_reg() const;
 #endif
 
   int GetNextChildId() {
     return IsSplinter() ? splintered_from()->GetNextChildId()
                         : ++last_child_id_;
   }
 
+  int GetChildCount() const { return last_child_id_ + 1; }
+
   bool IsSpilledOnlyInDeferredBlocks() const {
     return spilled_in_deferred_blocks_;
   }
 
   struct SpillMoveInsertionList;
 
   SpillMoveInsertionList* spill_move_insertion_locations() const {
     return spill_move_insertion_locations_;
   }
   void set_last_child(LiveRange* range) { last_child_ = range; }
@@ skipping 536 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_