Only call into the HOsrBuilder if required for OSR.

src/hydrogen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1763 matching lines @@
   virtual bool BuildGraph() V8_OVERRIDE;
 
   // Simple accessors.
   BreakAndContinueScope* break_scope() const { return break_scope_; }
   void set_break_scope(BreakAndContinueScope* head) { break_scope_ = head; }
 
   bool inline_bailout() { return inline_bailout_; }
 
   HValue* context() { return environment()->context(); }
 
+  HOsrBuilder* osr() const { return osr_; }
+
   void Bailout(BailoutReason reason);
 
   HBasicBlock* CreateJoin(HBasicBlock* first,
                           HBasicBlock* second,
                           BailoutId join_id);
 
   FunctionState* function_state() const { return function_state_; }
 
   void VisitDeclarations(ZoneList<Declaration*>* declarations);
 
@@ skipping 85 matching lines @@
   // the condition) and break_block is the block where control flow breaks
   // from the loop.  All blocks except loop_entry can be NULL.  The return
   // value is the new successor block which is the join of loop_successor
   // and break_block, or NULL.
   HBasicBlock* CreateLoop(IterationStatement* statement,
                           HBasicBlock* loop_entry,
                           HBasicBlock* body_exit,
                           HBasicBlock* loop_successor,
                           HBasicBlock* break_block);
 
+  // Build a loop entry
+  HBasicBlock* BuildLoopEntry();
+
+  // Builds a loop entry respectful of OSR requirements
+  HBasicBlock* BuildLoopEntry(IterationStatement* statement);
+
   HBasicBlock* JoinContinue(IterationStatement* statement,
                             HBasicBlock* exit_block,
                             HBasicBlock* continue_block);
 
   HValue* Top() const { return environment()->Top(); }
   void Drop(int n) { environment()->Drop(n); }
   void Bind(Variable* var, HValue* value) { environment()->Bind(var, value); }
   bool IsEligibleForEnvironmentLivenessAnalysis(Variable* var,
                                                 int index,
                                                 HValue* value,
@@ skipping 554 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_