Generators save and restore stack handlers

src/frames.h

Index: src/frames.h
diff --git a/src/frames.h b/src/frames.h
index 678191b950a0172a37f62a78fb9533f977502613..7b34bac49ba2c4bbe7a80fbd74720c78e1fbe560 100644
--- a/src/frames.h
+++ b/src/frames.h
@@ -107,7 +107,7 @@ class StackHandler BASE_EMBEDDED {
 
   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> {};
 
@@ -131,6 +131,13 @@ class StackHandler BASE_EMBEDDED {
   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;
@@ -541,6 +548,9 @@ class JavaScriptFrame: public StandardFrame {
   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;