Hydrogen LoopBuilder: add support for "while(true) {...}" loops

src/hydrogen.h

 // Copyright 2012 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_HYDROGEN_H_
 #define V8_HYDROGEN_H_
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 1651 matching lines @@
     int normal_merge_at_join_block_count_;
     int deopt_merge_at_join_block_count_;
   };
 
   class LoopBuilder V8_FINAL {
    public:
     enum Direction {
       kPreIncrement,
       kPostIncrement,
       kPreDecrement,
-      kPostDecrement
+      kPostDecrement,
+      kWhileTrue
     };
 
+    explicit LoopBuilder(HGraphBuilder* builder);  // while (true) {...}
     LoopBuilder(HGraphBuilder* builder,
                 HValue* context,
                 Direction direction);
     LoopBuilder(HGraphBuilder* builder,
                 HValue* context,
                 Direction direction,
                 HValue* increment_amount);
 
     ~LoopBuilder() {
       ASSERT(finished_);
     }
 
     HValue* BeginBody(
         HValue* initial,
         HValue* terminating,
         Token::Value token);
 
+    void BeginBody(int drop_count);
+
     void Break();
 
     void EndBody();
 
    private:
+    void Initialize(HGraphBuilder* builder, HValue* context,
+                    Direction direction, HValue* increment_amount);
     Zone* zone() { return builder_->zone(); }
 
     HGraphBuilder* builder_;
     HValue* context_;
     HValue* increment_amount_;
     HInstruction* increment_;
     HPhi* phi_;
     HBasicBlock* header_block_;
     HBasicBlock* body_block_;
     HBasicBlock* exit_block_;
@@ skipping 1188 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_