Experimental: thread live register references to deferred code....

src/virtual-frame-ia32.h

 // Copyright 2008 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 67 matching lines @@
 
   union {
     Register reg_;
     Object** handle_;
   } data_;
 
   CodeGenerator* cgen_;
 };
 
 
-// A result in a register just means that the value can be read from the register
-
-
 // -------------------------------------------------------------------------
 // Virtual frame elements
 //
 // The internal elements of the virtual frames.  There are several kinds of
 // elements:
 //   * Memory: an element that resides in the actual frame.  Its address is
 //     given by its position in the virtual frame.
 //   * Register: an element that resides in a register.
 //   * Constant: an element whose value is known at compile time.
 
@@ skipping 237 matching lines @@
   // push instruction.
   void EmitPush(Register reg);
   void EmitPush(Operand operand);
   void EmitPush(Immediate immediate);
 
   // Push an element on the virtual frame.
   void Push(Register reg);
   void Push(Handle<Object> value);
 
 #ifdef DEBUG
+  // True if all values in the frame are backed by memory.
   bool IsSpilled();
+
+  // True if the two frames have the same state (in which case they are
+  // interchangable).
+  bool Equals(VirtualFrame* other);
 #endif
 
  private:
   // An illegal index into the virtual frame.
   static const int kIllegalIndex = -1;
 
   static const int kLocal0Offset = JavaScriptFrameConstants::kLocal0Offset;
   static const int kFunctionOffset = JavaScriptFrameConstants::kFunctionOffset;
   static const int kContextOffset = StandardFrameConstants::kContextOffset;
 
@@ skipping 83 matching lines @@
 
   // Spill the topmost elements of the frame to memory (eg, they are the
   // arguments to a call) and all registers.
   void PrepareForCall(int count);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VIRTUAL_FRAME_IA32_H_