Generators save and restore stack handlers

src/frames.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 89 matching lines @@
  public:
   enum Kind {
     JS_ENTRY,
     CATCH,
     FINALLY,
     LAST_KIND = FINALLY
   };
 
   static const int kKindWidth = 2;
   STATIC_ASSERT(LAST_KIND < (1 << kKindWidth));
-  static const int kIndexWidth = 32 - kKindWidth;
+  static const int kIndexWidth = 32 - kSmiTagSize - kKindWidth;
   class KindField: public BitField<StackHandler::Kind, 0, kKindWidth> {};
   class IndexField: public BitField<unsigned, kKindWidth, kIndexWidth> {};
 
   // Get the address of this stack handler.
   inline Address address() const;
 
   // Get the next stack handler in the chain.
   inline StackHandler* next() const;
 
   // Tells whether the given address is inside this handler.
   inline bool includes(Address address) const;
 
   // Garbage collection support.
   inline void Iterate(ObjectVisitor* v, Code* holder) const;
 
   // Conversion support.
   static inline StackHandler* FromAddress(Address address);
 
   // Testers
   inline bool is_js_entry() const;
   inline bool is_catch() const;
   inline bool is_finally() const;
 
+  // Helpers to allow generators to capture and restore an activation's stack
+  // handlers.

[Michael Starzinger, 2013/05/07 09:55:44]

nit: How about shortening the comment to just "Generator support to preserve
stack handlers."

+  void Unwind(Isolate* isolate, FixedArray* array, int offset,
+              Object *data) const;

[Michael Starzinger, 2013/05/07 09:55:44]

Can we make "data" to be of type Smi? That would better describe it's usage.

+  Object* Rewind(Isolate* isolate, FixedArray* array, int offset,
+                 Address fp);

[Michael Starzinger, 2013/05/07 09:55:44]

nit: Should fit into one line.

+
  private:
   // Accessors.
   inline Kind kind() const;
 
   inline Object** context_address() const;
   inline Object** code_address() const;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StackHandler);
 };
 
@@ skipping 390 matching lines @@
   inline Object* GetParameter(int index) const;
   inline int ComputeParametersCount() const {
     return GetNumberOfIncomingArguments();
   }
 
   // Access the operand stack.
   inline Address GetOperandSlot(int index) const;
   inline Object* GetOperand(int index) const;
   inline int ComputeOperandsCount() const;
 
+  void SaveOperandStack(FixedArray* store, int* stack_handler_index) const;

[Michael Starzinger, 2013/05/07 09:55:44]

nit: Maybe add a one-liner comment "Generator support to preserve operand
stack."

+  void RestoreOperandStack(FixedArray* store, int stack_handler_index);
+
   // Debugger access.
   void SetParameterValue(int index, Object* value) const;
 
   // Check if this frame is a constructor frame invoked through 'new'.
   bool IsConstructor() const;
 
   // Check if this frame has "adapted" arguments in the sense that the
   // actual passed arguments are available in an arguments adaptor
   // frame below it on the stack.
   inline bool has_adapted_arguments() const;
@@ skipping 435 matching lines @@
 };
 
 
 // Reads all frames on the current stack and copies them into the current
 // zone memory.
 Vector<StackFrame*> CreateStackMap(Isolate* isolate, Zone* zone);
 
 } }  // namespace v8::internal
 
 #endif  // V8_FRAMES_H_