diff -r 11c81eb30246 -r 7c942b5adebc jitcraft/Stack.h
--- a/jitcraft/Stack.h	Sun Jul 08 17:57:44 2012 -0700
+++ b/jitcraft/Stack.h	Mon Jul 09 01:22:03 2012 -0700
@@ -31,6 +31,7 @@
 class Array;
 class Reference;
 class Frame;
+class Stack;
     
 union LocalSlot
 {
@@ -47,16 +48,6 @@
     LocalSlot *sp;
     bytecode *pc;
     Frame *fp;
-
-    Top(LocalSlot *sp, bytecode *pc, Frame *fp)
-      : sp(sp), pc(pc), fp(NULL)
-    {
-    }
-
-    Top(LocalSlot *sp)
-      : sp(sp), pc(NULL), fp(NULL)
-    {
-    }
 };
 
 class Frame
@@ -111,11 +102,34 @@
     void accept(VirtualObjectVisitor *visitor);
 };
 
+// RAII object for calling a function from C++.
+class InvokeArgs
+{
+    friend class Stack;
+
+    Stack *stack_;
+    LocalSlot *args_;
+    unsigned nargs_;
+
+  public:
+    InvokeArgs()
+      : stack_(NULL),
+        args_(NULL),
+        nargs_(0)
+    {
+    }
+
+    ~InvokeArgs();
+
+    LocalSlot &arg(unsigned index) {
+        assert(index < nargs_);
+        return args_[nargs_ - index - 1];
+    }
+};
+
 class Stack
 {
-    char *buffer_;
-    char *end_;
-    Top *top_;
+    friend class InvokeArgs;
 
   private:
     static const size_t STACK_SIZE = 1024 * 1024;
@@ -127,20 +141,24 @@
     bool initialize();
 
   public:
-    Frame *pushFrame(Function *fun);
-    Frame *popFrame();
+    Frame *pushInlineFrame(Handle<Function> fun);
+    Frame *popInlineFrame();
+
+    bool pushInvokeFrame(Handle<Function> fun, InvokeArgs &args);
 
     Top *top() {
-        return top_;
-    }
-    void setTop(Top *top) {
-        top_ = top;
-    }
-    Top begin() {
-        return Top((LocalSlot *)buffer_);
+        return &top_;
     }
     bool isInCallStack(Handle<Module> module);
     void accept(VirtualObjectVisitor *visitor);
+
+  private:
+    void popInvokeFrame(InvokeArgs &args);
+
+  private:
+    char *buffer_;
+    char *end_;
+    Top top_;
 };
 
 }