A start on allowing non-local control flow, for exceptions, try-finally, and ...

src/fast-codegen.h

 // Copyright 2009 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 25 matching lines @@
 namespace internal {
 
 
 class FastCodeGenerator: public AstVisitor {
  public:
   FastCodeGenerator(MacroAssembler* masm, Handle<Script> script, bool is_eval)
       : masm_(masm),
         function_(NULL),
         script_(script),
         is_eval_(is_eval),
+        function_return_(),
+        return_label_(NULL),
         loop_depth_(0),
         true_label_(NULL),
         false_label_(NULL) {
   }
 
   static Handle<Code> MakeCode(FunctionLiteral* fun,
                                Handle<Script> script,
                                bool is_eval);
 
   void Generate(FunctionLiteral* fun);
@@ skipping 54 matching lines @@
   AST_NODE_LIST(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
   // Handles the shortcutted logical binary operations in VisitBinaryOperation.
   void EmitLogicalOperation(BinaryOperation* expr);
 
   MacroAssembler* masm_;
   FunctionLiteral* function_;
   Handle<Script> script_;
   bool is_eval_;
-  Label return_label_;
+  Label function_return_;// Label of the actual return sequence.
+  Label* return_label_;  // Label to jump to from a return statement.
+  // If there are finally blocks from try..finally that must be executed,
+  // this is the entry point of a finally block, shadowing the real return.
+  int return_stack_height_;  // The height of the stack at return_label_.
+  int scope_stack_height_;  // The number of elements above the frame pointer
+  // that are on the stack due to enclosing scopes.  Does not include the
+  // expression stack, but does include elements pushed by with and for..in.
   int loop_depth_;
 
   Label* true_label_;
   Label* false_label_;
 
   DISALLOW_COPY_AND_ASSIGN(FastCodeGenerator);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FAST_CODEGEN_H_