Fix issue 265 by handling extra statement state on the frame based on...

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 62 matching lines @@
 
   int register_count(Register reg) {
     return frame_registers_.count(reg);
   }
 
   // Add extra in-memory elements to the top of the frame to match an actual
   // frame (eg, the frame after an exception handler is pushed).  No code is
   // emitted.
   void Adjust(int count);
 
-  // Forget elements from the top of the frame to match an actual frame (eg,
-  // the frame after a runtime call).  No code is emitted.
+  // Forget count elements from the top of the frame all in-memory
+  // (including synced) and adjust the stack pointer downward, to
+  // match an external frame effect (examples include a call removing
+  // its arguments, and exiting a try/catch removing an exception
+  // handler).  No code will be emitted.
   void Forget(int count);
 
+  // Forget count elements from the top of the frame without adjusting
+  // the stack pointer downward.  This is used, for example, before
+  // merging frames at break, continue, and return targets.
+  void ForgetElements(int count);
+
   // Spill all values from the frame to memory.
   void SpillAll();
 
   // Spill all occurrences of a specific register from the frame.
   void Spill(Register reg);
 
   // Spill all occurrences of an arbitrary register if possible.  Return the
   // register spilled or no_reg if it was not possible to free any register
   // (ie, they all have frame-external references).
   Register SpillAnyRegister();
@@ skipping 20 matching lines @@
   // binding a label.
   void AttachToCodeGenerator();
 
   // Emit code for the physical JS entry and exit frame sequences.  After
   // calling Enter, the virtual frame is ready for use; and after calling
   // Exit it should not be used.  Note that Enter does not allocate space in
   // the physical frame for storing frame-allocated locals.
   void Enter();
   void Exit();
 
-  // Prepare for returning from the frame by spilling locals and
-  // dropping all non-locals elements in the virtual frame.  This
+  // Prepare for returning from the frame by spilling locals.  This
   // avoids generating unnecessary merge code when jumping to the
   // shared return site.  Emits code for spills.
   void PrepareForReturn();
 
   // Allocate and initialize the frame-allocated locals.
   void AllocateStackSlots(int count);
 
   // An element of the expression stack as an assembly operand.
   Operand ElementAt(int index) const {
     return Operand(esp, index * kPointerSize);
@@ skipping 304 matching lines @@
   Result RawCallCodeObject(Handle<Code> code, RelocInfo::Mode rmode);
 
   bool Equals(VirtualFrame* other);
 
   friend class JumpTarget;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_VIRTUAL_FRAME_IA32_H_