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

src/jump-target.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 166 matching lines @@
 
 // -------------------------------------------------------------------------
 // Break targets
 //
 // A break target is a jump target that can be used to break out of a
 // statement that keeps extra state on the stack (eg, for/in or
 // try/finally).  They know the expected stack height at the target
 // and will drop state from nested statements as part of merging.
 //
 // Break targets are used for return, break, and continue targets.
+//
+// The fast compiler needs a similar object, containing a Label and
+// the stack height.  Since the parser already creates break targets
+// at all the appropriate sites, and creates the necessary links from
+// the AST to the break targets, we add an interface to break targets that
+// simply exposes the stack height and their underlying label, for use
+// in the fast compiler.
+
 
 class BreakTarget : public JumpTarget {
  public:
   // Construct a break target.
   BreakTarget() {}
 
   virtual ~BreakTarget() {}
 
   // Set the direction of the break target.
   virtual void set_direction(Directionality direction);
@@ skipping 18 matching lines @@
 
   // Bind a break target.  If there is no current frame at the binding
   // site, there must be at least one frame reaching via a forward
   // jump.
   virtual void Bind();
   virtual void Bind(Result* arg);
 
   // Setter for expected height.
   void set_expected_height(int expected) { expected_height_ = expected; }
 
+  // Added interface for the fast compiler:
+  int expected_height() { return expected_height_; }
+  // Label* entry_label() is already declared public in JumpTarget.
  private:
   // The expected height of the expression stack where the target will
   // be bound, statically known at initialization time.
   int expected_height_;
 
   DISALLOW_COPY_AND_ASSIGN(BreakTarget);
 };
 
 
 // -------------------------------------------------------------------------
@@ skipping 35 matching lines @@
   bool is_shadowing_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ShadowTarget);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_JUMP_TARGET_H_