Completely revamped NRE implementation, with (almost) unchanged API.

16 files changed, 641 insertions, 1199 deletions

diff --git a/generic/tcl.decls b/generic/tcl.decls
index 9700497..c67462e 100644
--- a/generic/tcl.decls
+++ b/generic/tcl.decls
@@ -12,7 +12,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: tcl.decls,v 1.141 2008/07/28 21:31:15 nijtmans Exp $
+# RCS: @(#) $Id: tcl.decls,v 1.142 2008/07/29 05:30:25 msofer Exp $
 
 library tcl
 
@@ -2108,25 +2108,31 @@ declare 581 generic {
     int Tcl_Canceled(Tcl_Interp *interp, int flags)
 }
 
-# NRE public interface
+# TIP#304 (chan pipe)
+
 declare 582 generic {
+    int Tcl_CreatePipe (Tcl_Interp  *interp, Tcl_Channel *rchan, Tcl_Channel *wchan, int flags)
+}
+
+# TIP #322 (NRE public interface)
+declare 583 generic {
     Tcl_Command Tcl_NRCreateCommand(Tcl_Interp *interp, 
 		    CONST char *cmdName, Tcl_ObjCmdProc *proc, 
 	            Tcl_ObjCmdProc *nreProc, ClientData clientData, 
 		    Tcl_CmdDeleteProc *deleteProc)
 }
-declare 583 generic {
+declare 584 generic {
     int Tcl_NREvalObj(Tcl_Interp *interp, Tcl_Obj *objPtr, int flags)
 }
-declare 584 generic {
+declare 585 generic {
     int Tcl_NREvalObjv(Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[],
 	    int flags)
 }
-declare 585 generic {
+declare 586 generic {
     int Tcl_NRCmdSwap(Tcl_Interp *interp, Tcl_Command cmd, int objc, 
-                      Tcl_Obj *CONST objv[])
+                      Tcl_Obj *CONST objv[], int flags)
 }
-declare 586 generic {
+declare 587 generic {
     void Tcl_NRAddCallback(Tcl_Interp *interp, Tcl_NRPostProc *postProcPtr, 
                       ClientData data0, ClientData data1,
                       ClientData data2, ClientData data3)
@@ -2134,18 +2140,12 @@ declare 586 generic {
 
 # For use by NR extenders, to have a simple way to also provide a (required!)
 # classic objProc 
-declare 587 generic {
+declare 588 generic {
     int Tcl_NRCallObjProc(Tcl_Interp *interp, Tcl_ObjCmdProc *objProc,
 			  ClientData clientData, int objc,
 	                     Tcl_Obj *CONST objv[])
 }
 
-# TIP#304 (chan pipe)
-
-declare 588 generic {
-    int Tcl_CreatePipe (Tcl_Interp  *interp, Tcl_Channel *rchan, Tcl_Channel *wchan, int flags)
-}
-
 ##############################################################################
 
 # Define the platform specific public Tcl interface.  These functions are
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 87a36b3..cb96099 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -16,7 +16,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclBasic.c,v 1.332 2008/07/28 21:06:09 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.333 2008/07/29 05:30:25 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -107,7 +107,7 @@ static int	DTraceObjCmd(ClientData dummy, Tcl_Interp *interp, int objc,
 MODULE_SCOPE const TclStubs * const tclConstStubsPtr;
 
 /*
- * Block for Tcl_EvalObjv helpers
+ * Tcl_EvalObjv helpers
  */
 
 static void		TEOV_SwitchVarFrame(Tcl_Interp *interp);
@@ -120,8 +120,6 @@ static int		TEOV_NotFound(Tcl_Interp *interp, int objc,
 static int		TEOV_RunEnterTraces(Tcl_Interp *interp,
 			    Command **cmdPtrPtr, int objc,
 			    Tcl_Obj *const objv[], Namespace *lookupNsPtr);
-static int		NRPostProcess(Tcl_Interp *interp, int result,
-			    int objc, Tcl_Obj *const objv[]);
 static Tcl_NRPostProc	TEOV_RestoreVarFrame;
 static Tcl_NRPostProc	TEOV_RunLeaveTraces;
 static Tcl_NRPostProc	TEOV_Exception;
@@ -129,7 +127,26 @@ static Tcl_NRPostProc	TEOV_Error;
 static Tcl_NRPostProc	TEOEx_ListCallback;
 static Tcl_NRPostProc	TEOEx_ByteCodeCallback;
 
-static Tcl_NRPostProc	TailcallCallback;
+static Tcl_NRPostProc   NRCommand;
+static Tcl_NRPostProc   NRRunObjProc;
+
+static Tcl_NRPostProc	EvalTailcall;
+
+#define NR_IS_COMMAND(callbackPtr) 			\
+    (callbackPtr					\
+	    && (callbackPtr->procPtr == NRCommand) 	\
+	    && (PTR2INT(callbackPtr->data[1])))
+
+#define NR_CLEAR_COMMAND(interp)			\
+    TEOV_callback *callbackPtr = TOP_CB(interp);	\
+							\
+    while (!NR_IS_COMMAND(callbackPtr)) {		\
+	callbackPtr = callbackPtr->nextPtr;		\
+    }							\
+    if (callbackPtr) {					\
+	callbackPtr->data[1] = INT2PTR(0);		\
+    }
+
 
 /*
  * The following structure define the commands in the Tcl core.
@@ -894,7 +911,7 @@ Tcl_CreateInterp(void)
 	Tcl_Panic(Tcl_GetString(Tcl_GetObjResult(interp)));
     }
 
-    TOP_RECORD(iPtr) = NULL;
+    TOP_CB(iPtr) = NULL;
     return interp;
 }
 
@@ -3950,7 +3967,7 @@ Tcl_CancelEval(
  *	TCL_ERROR. A result or error message is left in interp's result.
  *
  * Side effects:
- *	Depends on the command.
+ *	Always pushes a callback. Other side effects depend on the command. 
  *
  *----------------------------------------------------------------------
  */
@@ -3967,11 +3984,15 @@ Tcl_EvalObjv(
 				 * TCL_EVAL_GLOBAL, TCL_EVAL_INVOKE and
 				 * TCL_EVAL_NOERR are currently supported. */
 {
-    return TclEvalObjv(interp, objc, objv, flags, NULL);
+    int result;
+    TEOV_callback *rootPtr = TOP_CB(interp);
+
+    result = TclNREvalObjv(interp, objc, objv, flags, NULL);
+    return   TclNRRunCallbacks(interp, result, rootPtr, 0);
 }
 
 int
-TclEvalObjv(
+TclNREvalObjv(
     Tcl_Interp *interp,		/* Interpreter in which to evaluate the
 				 * command. Also used for error reporting. */
     int objc,			/* Number of words in command. */
@@ -3987,40 +4008,38 @@ TclEvalObjv(
 {
     Interp *iPtr = (Interp *) interp;
     int result;
-    Namespace *lookupNsPtr = NULL;
-    TEOV_record *rootPtr = TOP_RECORD(iPtr);
-    TEOV_record *recordPtr;
+    Namespace *lookupNsPtr = iPtr->lookupNsPtr;
     Tcl_ObjCmdProc *objProc;
     ClientData objClientData;
-    int tebcCall = TEBC_CALL(iPtr);
-
-    TEBC_CALL(iPtr) = 0;
-
-    if (cmdPtr) {
-	if (iPtr->lookupNsPtr) {
-	    iPtr->lookupNsPtr = NULL;
-	}
-	PUSH_RECORD(interp, recordPtr);
-	goto commandFound;
-    }
+    Command **cmdPtrPtr;
+    
+    iPtr->lookupNsPtr = NULL;
+    
+    /*
+     * Push a callback with cleanup tasks for commands; the cmdPtr at data[0]
+     * will be filled later when the command is found: save its address at
+     * objProcPtr.
+     *
+     * data[1] stores a marker for use by tailcalls; it will be reset to 0 by
+     * command redirectors (imports, alias, ensembles) so that tailcalls
+     * finishes the source command and not just the target.
+     */
 
-  restartAtTop:
+    TclNRAddCallback(interp, NRCommand, NULL, INT2PTR(1),
+	    NULL, NULL);
+    cmdPtrPtr = (Command **) &(TOP_CB(interp)->data[0]);
+    
     TclResetCancellation(interp, 0);
     iPtr->numLevels++;
     result = TclInterpReady(interp);
 
     if ((result != TCL_OK) || (objc == 0)) {
-	iPtr->lookupNsPtr = NULL;
-	iPtr->numLevels--;
-	goto done;
+	return result;
     }
 
-    /*
-     * Always push a record for the command (avoid queuing callbacks for an
-     * older command!)
-     */
-
-    PUSH_RECORD(interp, recordPtr);
+    if (cmdPtr) {
+	goto commandFound;
+    }
 
     /*
      * Push records for task to be done on return, in INVERSE order. First, if
@@ -4035,12 +4054,9 @@ TclEvalObjv(
      * Configure evaluation context to match the requested flags.
      */
 
-    lookupNsPtr = iPtr->lookupNsPtr;
     if ((flags & TCL_EVAL_INVOKE) || lookupNsPtr) {
 	if (!lookupNsPtr) {
 	    lookupNsPtr = iPtr->globalNsPtr;
-	} else {
-	    iPtr->lookupNsPtr = NULL;
 	}
     } else {
 	if (flags & TCL_EVAL_GLOBAL) {
@@ -4063,15 +4079,12 @@ TclEvalObjv(
     if (!cmdPtr) {
       notFound:
 	result = TEOV_NotFound(interp, objc, objv, lookupNsPtr);
-	iPtr->numLevels--;
-	goto done;
+	return result;
     }
 
     iPtr->cmdCount++;
     if (TclLimitExceeded(iPtr->limit)) {
-	result = TCL_ERROR;
-	iPtr->numLevels--;
-	goto done;
+	return TCL_ERROR;
     }
 
     /*
@@ -4090,8 +4103,7 @@ TclEvalObjv(
 	    goto notFound;
 	}
 	if (result != TCL_OK) {
-	    iPtr->numLevels--;
-	    goto done;
+	    return result;
 	}
     }
 
@@ -4115,154 +4127,38 @@ TclEvalObjv(
     }
 
     /*
-     * Finally, invoke the command's Tcl_ObjCmdProc.
-     *
-     * Do the NR dance right here:
-     *  - for non-NR enabled commands, just sigh and call the objProc
-     *  - for NR-enabled commands call the part1, decide what to do with the
-     *    continuation:
-     *       . if it is a bytecode AND we were called by TEBC, pass it back.
-     *	       Otherwise just call a new TEBC on it. Don't register the
-     *	       callback, TEBC handles those.
-     *	     . if it is a command and it has a callback, push the callback
-     *	       into the TODO list, set the params as needed and restart at the
-     *	       top.
-     *
-     * Note that I removed the DTRACE thing: I have not really thought about
-     * where it really belongs, and do not really know what it does either.
+     * Fix the original callback to point to the now known cmdPtr. Insure that
+     * the Command struct lives until the command returns.
      */
 
-    objProc = cmdPtr->nreProc;
-    if (!objProc) {
-	objProc = cmdPtr->objProc;
-    }
-    objClientData = cmdPtr->objClientData;
-
-    COMPLETE_RECORD(recordPtr);
+    *cmdPtrPtr = cmdPtr;
     cmdPtr->refCount++;
-
-    /*
-     * If this is an NR-enabled command, find the real objProc.
-     */
-
-    result = (*objProc)(objClientData, interp, objc, objv);
-    if (result != TCL_OK) {
-#if 0
-	TclStackPurge(interp, recordPtr->tosPtr);
-#endif
-	goto done;
-    }
-
+    
     /*
-     * We got a valid callback request: let us complete the corresponding
-     * record and proceed with the next call.
+     * Find the objProc to call: nreProc if available, objProc otherwise. Push
+     * a callback to do the actual running.
      */
 
-  callbackReentryPoint:
-    switch(recordPtr->type) {
-    case TCL_NR_NO_TYPE:
-	break;
-    case TCL_NR_BC_TYPE:
-    tcl_nr_bc_type:
-	if (USE_NR_TEBC && tebcCall) {
-	    return TCL_OK;
-	}
-
-	/*
-	 * No TEBC atop - we'll just have to instantiate a new one and do the
-	 * callback on return.
-	 */
-
-	result = TclExecuteByteCode(interp, recordPtr->data.codePtr);
-	goto done;
-    case TCL_NR_TAILCALL_TYPE:
-	/*
-	 * Proceed to cleanup the current command, the tailcall will be run
-	 * from the callbacks.
-	 */
-
-	if (USE_NR_TEBC && tebcCall) {
-	    return TCL_OK;
-	}
-	recordPtr->type = TCL_NR_NO_TYPE;
-	break;
-    case TCL_NR_CMD_TYPE: {
-	/*
-	 * We got an unshared canonical list to eval , do it from here.
-	 */
-
-	Tcl_Obj *objPtr = recordPtr->data.obj.objPtr;
-	Tcl_Obj **elemPtr;
-
-	flags = recordPtr->data.obj.flags;
-	Tcl_ListObjGetElements(NULL, objPtr, &objc, &elemPtr);
-	objv = elemPtr;
-	if (objc != 0) {
-	    goto restartAtTop;
-	}
-	goto done;
-    }
-    case TCL_NR_SCRIPT_TYPE: {
-	Tcl_Obj *objPtr = recordPtr->data.obj.objPtr;
-
-	flags = recordPtr->data.obj.flags;
-	if (USE_NR_TEBC && tebcCall) {
-	    result = TclNREvalObjEx(interp, objPtr, flags, NULL, 0);
-	    if (result == TCL_OK) {
-		switch (recordPtr->type) {
-		case TCL_NR_BC_TYPE:
-		    goto tcl_nr_bc_type;
-		case TCL_NR_NO_TYPE:
-		    goto done;
-		default:
-		    Tcl_Panic("TEOEx called from TEOV returns unexpected record type: %d",
-			    recordPtr->type);
-		}
-	    }
-	} else {
-	    result = TclEvalObjEx(interp, objPtr, flags, NULL, 0);
-	}
-	goto done;
-    }
-    case TCL_NR_CMDSWAP_TYPE:
-	/*
-	 * This is a cmdPtr swap like ns-import does.
-	 */
-
-	cmdPtr = recordPtr->cmdPtr;
-	objc   = recordPtr->data.objcv.objc;
-	objv   = recordPtr->data.objcv.objv;
-	recordPtr->type = TCL_NR_NO_TYPE;
-	goto commandFound;
-    default:
-	Tcl_Panic("TEOV: unknown NR-request type %i!", recordPtr->type);
-    }
-
-  done:
-    result = TclEvalObjv_NR2(interp, result, rootPtr);
-    recordPtr = TOP_RECORD(iPtr);
-    if (recordPtr == rootPtr) {
-	return result;
+    objProc = cmdPtr->nreProc;
+    if (!objProc) {
+	objProc = cmdPtr->objProc;
     }
+    objClientData = cmdPtr->objClientData;
 
-    /*
-     * A callback scheduled a new evaluation! Deal with it.
-     * Note that recordPtr was already updated right above.
-     */
-
-    assert((result == TCL_OK));
-    goto callbackReentryPoint;
+    TclNRAddCallback(interp, NRRunObjProc, objProc, objClientData,
+	    INT2PTR(objc), (ClientData) objv);
+    return TCL_OK;
 }
 
 int
-TclEvalObjv_NR2(
+TclNRRunCallbacks(
     Tcl_Interp *interp,
     int result,
-    struct TEOV_record *rootPtr)
+    struct TEOV_callback *rootPtr,
+    int tebcCall)
 {
     Interp *iPtr = (Interp *) interp;
-    TEOV_record *recordPtr;
-    TEOV_callback *callbackPtr;
+    TEOV_callback *callbackPtr = TOP_CB(interp);
 
     /*
      * If the interpreter has a non-empty string result, the result object is
@@ -4278,68 +4174,57 @@ TclEvalObjv_NR2(
 	(void) Tcl_GetObjResult(interp);
     }
 
-  restart:
-    while ((recordPtr = TOP_RECORD(iPtr)) != rootPtr) {
-	while (recordPtr->callbackPtr) {
-	    callbackPtr = recordPtr->callbackPtr;
-	    recordPtr->callbackPtr = callbackPtr->nextPtr;
-	    result = callbackPtr->procPtr(callbackPtr->data, interp, result);
-	    TclSmallFree(callbackPtr);
-
-	    if (recordPtr != TOP_RECORD(iPtr)) {
-
-		if (result != TCL_OK) {
-		    goto restart;
-		}
+    while (TOP_CB(interp) != rootPtr) {
+	callbackPtr = TOP_CB(interp);
 
+	if (tebcCall) {
+	    if ((callbackPtr->procPtr == NRRunBytecode) ||
+		    (callbackPtr->procPtr == NRDropCommand)) {
 		/*
-		 * A callback scheduled a new evaluation; return so that our
-		 * caller can run it.
+		 * TEBC pass thru: let the caller tebc handle and get rid of
+		 * this callback.
 		 */
 
-		switch(recordPtr->type) {
-		    case TCL_NR_NO_TYPE:
-			goto restart;
-		    case TCL_NR_BC_TYPE:
-		    case TCL_NR_CMD_TYPE:
-		    case TCL_NR_SCRIPT_TYPE:
-		    case TCL_NR_CMDSWAP_TYPE:
-			goto done;
-		    case TCL_NR_TAILCALL_TYPE:
-			Tcl_Panic("Tailcall called from a callback!");
-		    default:
-			Tcl_Panic("TEOV_NR2: invalid record type: %d",
-				recordPtr->type);
-		}
+		return TCL_OK;
 	    }
 	}
-	TOP_RECORD(iPtr) = recordPtr->nextPtr;
-
-	if (!CHECK_EXTRA(iPtr, recordPtr)) {
-	    Tcl_Panic("TclEvalObjv_NR2: wrong tosPtr?");
-	    /* TclStackPurge(interp, recordPtr->tosPtr); */
-	}
 
 	/*
-	 * Decrement the reference count of cmdPtr and deallocate it if it has
-	 * dropped to zero. The level only needs fixing for records that
-	 * pushed a cmdPtr.
+	 * IMPLEMENTATION REMARKS (FIXME)
+	 *
+	 * Add here other direct handling possibilities for optimisation?
+	 * One could handle the very frequent NRCommand and  NRRunObjProc right
+	 * here to save an indirect function call and improve icache
+	 * management. Would it? Test it, time it ...
 	 */
 
-	if (recordPtr->cmdPtr) {
-	    TclCleanupCommandMacro(recordPtr->cmdPtr);
-	    iPtr->numLevels--;
-	}
-
-	FREE_RECORD(iPtr, recordPtr);
+	TOP_CB(interp) = callbackPtr->nextPtr;
+	result = callbackPtr->procPtr(callbackPtr->data, interp, result);
+	TCLNR_FREE(interp, callbackPtr);
     }
+    return result;
+}
 
-    /*
-     * Do not interrupt a series of cleanups with async or limit checks: just
-     * check at the end.
-     */
+static int
+NRCommand(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    Interp *iPtr = (Interp *) interp;
+    Command *cmdPtr = data[0];
+    /* int cmdStart = PTR2INT(data[1]); NOT USED HERE */
 
-    done:
+    
+    if (cmdPtr) {
+	TclCleanupCommandMacro(cmdPtr);
+    }
+    ((Interp *)interp)->numLevels--;
+    
+    /* OPT ??
+     * Do not interrupt a series of cleanups with async or limit checks:
+     * just check at the end?
+     */
 
     if (TclAsyncReady(iPtr)) {
 	result = Tcl_AsyncInvoke(interp, result);
@@ -4350,6 +4235,52 @@ TclEvalObjv_NR2(
     if (result == TCL_OK && TclLimitReady(iPtr->limit)) {
 	result = Tcl_LimitCheck(interp);
     }
+    return result;
+}
+    
+static int
+NRRunObjProc(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    /* OPT: do not call? */
+
+    Tcl_ObjCmdProc *objProc = data[0];
+    ClientData objClientData = data[1];
+    int objc = PTR2INT(data[2]);
+    Tcl_Obj **objv = data[3];
+
+    if (result == TCL_OK) {
+	return (*objProc)(objClientData, interp, objc, objv);
+    }
+    return result;
+}
+
+int
+NRRunBytecode(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    ByteCode *codePtr = data[0];
+
+    if (result == TCL_OK) {
+	return TclExecuteByteCode(interp, codePtr);
+    }
+    return result;
+}
+
+int
+NRDropCommand(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    /* For tailcalls!
+     * drop all callbacks until the last command start: nothing to do here,
+     * just need this to be able to pass it up to tebc.
+     */
 
     return result;
 }
@@ -4670,7 +4601,7 @@ TEOV_RunLeaveTraces(
     Tcl_DecrRefCount(commandPtr);
 
     /*
-     * As cmdPtr is set, TclEvalObjv_NR2 is about to reduce the numlevels.
+     * As cmdPtr is set, TclNRRunCallbacks is about to reduce the numlevels.
      * Prevent that by resetting the cmdPtr field and dealing right here with
      * cmdPtr->refCount.
      */
@@ -5110,7 +5041,7 @@ TclEvalEx(
 
 	    TclArgumentEnter(interp, objv, objectsUsed, eeFramePtr);
 	    iPtr->cmdFramePtr = eeFramePtr;
-	    code = TclEvalObjv(interp, objectsUsed, objv, TCL_EVAL_NOERR, NULL);
+	    code = Tcl_EvalObjv(interp, objectsUsed, objv, TCL_EVAL_NOERR);
 	    iPtr->cmdFramePtr = iPtr->cmdFramePtr->nextPtr;
 	    TclArgumentRelease(interp, objv, objectsUsed);
 
@@ -5706,17 +5637,10 @@ TclEvalObjEx(
     int word)			/* Index of the word which is in objPtr. */
 {
     int result = TCL_OK;
-    TEOV_record *recordPtr;
-
-    /*
-     * Push an empty record. If this is an NR call, it will modify it
-     * accordingly.
-     */
+    TEOV_callback *rootPtr = TOP_CB(interp);
 
-    PUSH_RECORD(interp, recordPtr);
     result = TclNREvalObjEx(interp, objPtr, flags, invoker, word);
-    assert((TOP_RECORD(interp) == recordPtr));
-    return NRPostProcess(interp, result, 0, NULL);
+    return   TclNRRunCallbacks(interp, result, rootPtr, 0);
 }
 
 int
@@ -5759,28 +5683,15 @@ TclNREvalObjEx(
 
 	if (objPtr->bytes == NULL ||		/* ...without a string rep */
 		listRepPtr->canonicalFlag) {	/* ...or that is canonical */
+	    Tcl_Obj *listPtr = objPtr;
+	    CmdFrame *eoFramePtr = NULL;
+	    int objc;
+	    Tcl_Obj **objv;
+	    
 	    /*
 	     * TIP #280 Structures for tracking lines. As we know that this is
 	     * dynamic execution we ignore the invoker, even if known.
-	     */
-
-	    CmdFrame *eoFramePtr;
-
-	    eoFramePtr = (CmdFrame *) TclStackAlloc(interp, sizeof(CmdFrame));
-	    eoFramePtr->nline = 0;
-	    eoFramePtr->line = NULL;
-
-	    eoFramePtr->type = TCL_LOCATION_EVAL_LIST;
-	    eoFramePtr->level = (iPtr->cmdFramePtr == NULL?
-		    1 : iPtr->cmdFramePtr->level + 1);
-	    eoFramePtr->numLevels = iPtr->numLevels;
-	    eoFramePtr->framePtr = iPtr->framePtr;
-	    eoFramePtr->nextPtr = iPtr->cmdFramePtr;
-
-	    eoFramePtr->cmd.listPtr  = objPtr;
-	    eoFramePtr->data.eval.path = NULL;
-
-	    /*
+	     *
 	     * TIP #280. We do _not_ compute all the line numbers for the
 	     * words in the command. For the eval of a pure list the most
 	     * sensible choice is to put all words on line 1. Given that we
@@ -5788,13 +5699,44 @@ TclNREvalObjEx(
 	     * left NULL. The two places using this information (TclInfoFrame,
 	     * and TclInitCompileEnv), are special-cased to use the proper
 	     * line number directly instead of accessing the 'line' array.
+	     *
+	     * Note that we use (word==INTMIN) to signal that no command frame
+	     * should be pushed, as needed by alias and ensemble redirections.
 	     */
 
-	    iPtr->cmdFramePtr = eoFramePtr;
+	    if (word != INT_MIN) {
+		eoFramePtr = (CmdFrame *) TclStackAlloc(interp, sizeof(CmdFrame));
+		eoFramePtr->nline = 0;
+		eoFramePtr->line = NULL;
+		
+		eoFramePtr->type = TCL_LOCATION_EVAL_LIST;
+		eoFramePtr->level = (iPtr->cmdFramePtr == NULL?
+			1 : iPtr->cmdFramePtr->level + 1);
+		eoFramePtr->numLevels = iPtr->numLevels;
+		eoFramePtr->framePtr = iPtr->framePtr;
+		eoFramePtr->nextPtr = iPtr->cmdFramePtr;
+		
+		eoFramePtr->cmd.listPtr  = objPtr;
+		eoFramePtr->data.eval.path = NULL;
+		
+		iPtr->cmdFramePtr = eoFramePtr;
+	    }
+
+	    /*
+	     * Shimmer protection! Always pass an unshared obj. The caller could
+	     * incr the refCount of objPtr AFTER calling us! To be completely safe
+	     * we always make a copy.
+	     *
+	     * FIXME OPT: preserve just the internal rep? 
+	     */
 
+	    listPtr = TclListObjCopy(interp, objPtr);
+	    Tcl_IncrRefCount(listPtr);
 	    TclNRAddCallback(interp, TEOEx_ListCallback, objPtr, eoFramePtr,
-		     NULL, NULL);
-	    return Tcl_NREvalObj(interp, objPtr, flags);
+		     listPtr, NULL);
+
+	    ListObjGetElements(listPtr, objc, objv);
+	    return TclNREvalObjv(interp, objc, objv, flags, NULL);	    
 	}
     }
 
@@ -5806,7 +5748,7 @@ TclNREvalObjEx(
 	 * We transfer this to the byte code compiler.
 	 */
 
-	ByteCode *newCodePtr;
+	ByteCode *codePtr;
 	CallFrame *savedVarFramePtr = NULL;	/* Saves old copy of
 						 * iPtr->varFramePtr in case
 						 * TCL_EVAL_GLOBAL was set. */
@@ -5815,18 +5757,12 @@ TclNREvalObjEx(
 	    savedVarFramePtr = iPtr->varFramePtr;
 	    iPtr->varFramePtr = iPtr->rootFramePtr;
 	}
+	codePtr = TclCompileObj(interp, objPtr, invoker, word);
+
 	TclNRAddCallback(interp, TEOEx_ByteCodeCallback, savedVarFramePtr,
 		    objPtr, INT2PTR(allowExceptions), NULL);
-
-	newCodePtr = TclCompileObj(interp, objPtr, invoker, word);
-	if (newCodePtr) {
-	    TEOV_record *recordPtr = TOP_RECORD(interp);
-
-	    recordPtr->type = TCL_NR_BC_TYPE;
-	    recordPtr->data.codePtr = newCodePtr;
-	    return TCL_OK;
-	}
-	return TCL_ERROR;
+	TclNRAddCallback(interp, NRRunBytecode, codePtr, NULL, NULL, NULL);
+	return TCL_OK;
     }
 
     /*
@@ -5962,14 +5898,18 @@ TEOEx_ListCallback(
     Interp *iPtr = (Interp *) interp;
     Tcl_Obj *objPtr = data[0];
     CmdFrame *eoFramePtr = data[1];
+    Tcl_Obj *listPtr = data[2];
 
     /*
      * Remove the cmdFrame
      */
 
-    iPtr->cmdFramePtr = eoFramePtr->nextPtr;
-    TclStackFree(interp, eoFramePtr);
+    if (eoFramePtr) {
+	iPtr->cmdFramePtr = eoFramePtr->nextPtr;
+	TclStackFree(interp, eoFramePtr);
+    }
     TclDecrRefCount(objPtr);
+    TclDecrRefCount(listPtr);
 
     return result;
 }
@@ -7764,76 +7704,10 @@ Tcl_NRCallObjProc(
     Tcl_Obj *const objv[])
 {
     int result = TCL_OK;
-    TEOV_record *recordPtr;
+    TEOV_callback *rootPtr = TOP_CB(interp);
 
-    /*
-     * Push an empty record. If this is an NR call, it will modify it
-     * accordingly.
-     */
-
-    PUSH_RECORD(interp, recordPtr);
     result = (*objProc)(clientData, interp, objc, objv);
-    return NRPostProcess(interp, result, objc, objv);
-}
-
-static int
-NRPostProcess(
-    Tcl_Interp *interp,
-    int result,
-    int objc,
-    Tcl_Obj *const objv[])
-{
-    TEOV_record *recordPtr, *rootPtr = TOP_RECORD(interp)->nextPtr;
-
-  restart:
-    recordPtr = TOP_RECORD(interp);
-    if (result == TCL_OK) {
-	switch (recordPtr->type) {
-	    case TCL_NR_NO_TYPE:
-		break;
-	    case TCL_NR_BC_TYPE:
-		result = TclExecuteByteCode(interp, recordPtr->data.codePtr);
-		break;
-	    case TCL_NR_TAILCALL_TYPE:
-		Tcl_SetResult(interp,
-			"impossible to tailcall from a non-NRE enabled command",
-			TCL_STATIC);
-		result = TCL_ERROR;
-		break;
-	    case TCL_NR_CMD_TYPE: {
-		Tcl_Obj *objPtr = recordPtr->data.obj.objPtr;
-		int flags = recordPtr->data.obj.flags;
-		Tcl_Obj **objv;
-		int objc;
-
-		Tcl_ListObjGetElements(NULL, objPtr, &objc, &objv);
-		result = TclEvalObjv(interp, objc, objv, flags, NULL);
-		break;
-	    }
-	    case TCL_NR_SCRIPT_TYPE: {
-		Tcl_Obj *objPtr = recordPtr->data.obj.objPtr;
-		int flags = recordPtr->data.obj.flags;
-
-		result = TclNREvalObjEx(interp, objPtr, flags, NULL, 0);
-		break;
-	    }
-	    case TCL_NR_CMDSWAP_TYPE: {
-		result = TclEvalObjv(interp, recordPtr->data.objcv.objc,
-			recordPtr->data.objcv.objv, 0, recordPtr->cmdPtr);
-		break;
-	    }
-	    default:
-		Tcl_Panic("NRPostProcess: invalid record type: %d",
-			recordPtr->type);
-	}
-    }
-
-    result = TclEvalObjv_NR2(interp, result, rootPtr);
-    if (TOP_RECORD(interp) != rootPtr) {
-	assert((result == TCL_OK));
-	goto restart;
-    }
-    return result;
+    return TclNRRunCallbacks(interp, result, rootPtr, 0);
 }
 
 /*
@@ -7891,31 +7765,18 @@ Tcl_NRCreateCommand(
     return (Tcl_Command) cmdPtr;
 }
 
-/*
- * These are the previous contents of tclNRE.c, part of the NRE api.
- *
- * TclNREvalCmd should only be called as an optimisation: when objPtr is known
- * to be a canonical list that is not (and will not!) be shared
- */
+/****************************************************************************
+ * Stuff for the public api
+ ****************************************************************************/
 
 int
-TclNREvalCmd(
+Tcl_NREvalObj(
     Tcl_Interp *interp,
     Tcl_Obj *objPtr,
     int flags)
 {
-    TEOV_record *recordPtr = TOP_RECORD(interp);
-
-    Tcl_IncrRefCount(objPtr);
-    recordPtr->type = TCL_NR_CMD_TYPE;
-    recordPtr->data.obj.objPtr = objPtr;
-    recordPtr->data.obj.flags = flags;
-    return TCL_OK;
+    return TclNREvalObjEx(interp, objPtr, flags, NULL, INT_MIN);
 }
-
-/****************************************************************************
- * Stuff for the public api
- ****************************************************************************/
 
 int
 Tcl_NREvalObjv(
@@ -7929,42 +7790,14 @@ Tcl_NREvalObjv(
 				 * TCL_EVAL_GLOBAL, TCL_EVAL_INVOKE and
 				 * TCL_EVAL_NOERR are currently supported. */
 {
-    Tcl_Obj *listPtr = Tcl_NewListObj(objc, objv);
-
-    return TclNREvalCmd(interp, listPtr, flags);
+    return TclNREvalObjv(interp, objc, objv, flags, NULL);
 }
 
-int
-Tcl_NREvalObj(
-    Tcl_Interp *interp,
-    Tcl_Obj *objPtr,
-    int flags)
+void
+TclNRClearCommandFlag(
+    Tcl_Interp *interp)
 {
-    TEOV_record *recordPtr = TOP_RECORD(interp);
-    List *listRep = objPtr->internalRep.twoPtrValue.ptr1;
-
-    Tcl_IncrRefCount(objPtr);
-    if ((objPtr->typePtr == &tclListType)
-	    && (!objPtr->bytes || listRep->canonicalFlag)) {
-	/*
-	 * Shimmer protection! Always pass an unshared obj. The caller could
-	 * incr the refCount of objPtr AFTER calling us! To be completely safe
-	 * we always make a copy.
-	 */
-
-	Tcl_Obj *origPtr = objPtr;
-
-	objPtr = TclListObjCopy(NULL, origPtr);
-	Tcl_IncrRefCount(objPtr);
-	TclDecrRefCount(origPtr);
-
-	recordPtr->type = TCL_NR_CMD_TYPE;
-    } else {
-	recordPtr->type = TCL_NR_SCRIPT_TYPE;
-    }
-    recordPtr->data.obj.objPtr = objPtr;
-    recordPtr->data.obj.flags = flags;
-    return TCL_OK;
+    NR_CLEAR_COMMAND(interp);
 }
 
 int
@@ -7972,16 +7805,14 @@ Tcl_NRCmdSwap(
     Tcl_Interp *interp,
     Tcl_Command cmd,
     int objc,
-    Tcl_Obj *const objv[])
+    Tcl_Obj *const objv[],
+    int flags)
 {
-    TEOV_record *recordPtr = TOP_RECORD(interp);
-
-    recordPtr->type = TCL_NR_CMDSWAP_TYPE;
-    recordPtr->cmdPtr = (Command *) cmd;
-    recordPtr->data.objcv.objc = objc;
-    recordPtr->data.objcv.objv = (Tcl_Obj **) objv;
+    int result;
 
-    return TCL_OK;
+    result = TclNREvalObjv(interp, objc, objv, flags, (Command *)cmd);
+    NR_CLEAR_COMMAND(interp);
+    return result;
 }
 
 /*****************************************************************************
@@ -8016,85 +7847,82 @@ TclTailcallObjCmd(
     Tcl_Obj *const objv[])
 {
     Interp *iPtr = (Interp *) interp;
-    TEOV_record *rootPtr = TOP_RECORD(interp);
-    TEOV_callback *headPtr, *tailPtr;
-    TEOV_record *tmpPtr;
-    Tcl_Obj *listPtr;
+    TEOV_callback *rootPtr = TOP_CB(interp);
+    TEOV_callback *tailPtr;
+    Tcl_Obj *scriptPtr;
     Namespace *nsPtr = iPtr->varFramePtr->nsPtr;
-
-    if (!iPtr->varFramePtr->isProcCallFrame) {
-	/* FIXME! Why error? Just look if we have a TEOV above! */
-	Tcl_SetResult(interp,
-	    "tailcall can only be called from a proc or lambda", TCL_STATIC);
-	return TCL_ERROR;
+    int count;
+    
+    if (objc < 2) {
+	Tcl_WrongNumArgs(interp, 1, objv, "command ?arg ...?");
     }
 
-    nsPtr->activationCount++;
-    listPtr = Tcl_NewListObj(objc-1, objv+1);
-    rootPtr->type = TCL_NR_TAILCALL_TYPE;
-
     /*
-     * Add a callback to perform the tailcall as LAST item in the caller's
+     * Add a callback to perform the tailcall as LAST item in the CALLER's
      * callback stack.
-     * Find the first record for the caller: start at the one below the top
-     * (the top being this command's record), and go back until you find
-     * the one that contains the cmdPtr.
+     * Find the first record for the caller:
+     *  1. find the SECOND callback that contains a cmdPtr below the top (note
+     *     that the FIRST one correspond to this TclTailcallObjCmd call)
+     *  2. set the callback for the tailcalled command below that
      */
 
-    tmpPtr = rootPtr->nextPtr;
-    while (tmpPtr->cmdPtr == NULL) {
-	tmpPtr = tmpPtr->nextPtr;
+    tailPtr = rootPtr;
+    count = NR_IS_COMMAND(tailPtr);
+    while (tailPtr && tailPtr->nextPtr && (count < 2)) {
+	tailPtr = tailPtr->nextPtr;
+	count += NR_IS_COMMAND(tailPtr);
     }
 
-    /*
-     * Now find the first and last callbacks in this record, and temporarily
-     * set the callback list to empty.
-     */
-
-    headPtr = tailPtr = tmpPtr->callbackPtr;
-    if (headPtr) {
-	while (tailPtr->nextPtr) {
-	    tailPtr = tailPtr->nextPtr;
-	}
-	tmpPtr->callbackPtr = NULL;
+#if 1
+    if (!iPtr->varFramePtr->isProcCallFrame) {
+	/* FIXME! Why error? Just look if we have a TEOV above! */
+	Tcl_SetResult(interp,
+	    "tailcall can only be called from a proc or lambda", TCL_STATIC);
+	return TCL_ERROR;
+    }
+#else
+    if (!tailPtr->nextPtr) {
+	/* FIXME! Is this the behaviour we want? */
+	Tcl_SetResult(interp,
+	    "cannot tailcall: not running a command", TCL_STATIC);
+	return TCL_ERROR;
     }
+#endif
 
     /*
-     * Temporarily put tmpPtr as the TOP_RECORD, register a callback, then
+     * Temporarily put NULL as the TOP_BC, register a callback, then
      * replug things back the way they were.
      */
 
-    TOP_RECORD(iPtr) = tmpPtr;
-    TclNRAddCallback(interp, TailcallCallback, listPtr, nsPtr, NULL, NULL);
-    TOP_RECORD(iPtr) = rootPtr;
-
-    if (headPtr) {
-	tailPtr->nextPtr = tmpPtr->callbackPtr;
-	tmpPtr->callbackPtr = headPtr;
+    nsPtr->activationCount++;
+    if (objc == 2) {
+	scriptPtr = objv[1];
+    } else {
+	scriptPtr = Tcl_NewListObj(objc-1, objv+1);
     }
 
+    TOP_CB(iPtr) = tailPtr->nextPtr;
+    TclNRAddCallback(interp, EvalTailcall, scriptPtr, nsPtr, NULL, NULL);
+    tailPtr->nextPtr = TOP_CB(iPtr);
+    TOP_CB(iPtr) = rootPtr;
+
+    TclNRAddCallback(interp, NRDropCommand, NULL, NULL, NULL, NULL);
     return TCL_OK;
 }
 
 static int
-TailcallCallback(
+EvalTailcall(
     ClientData data[],
     Tcl_Interp *interp,
     int result)
 {
     Interp *iPtr = (Interp *) interp;
-    Tcl_Obj *listPtr = data[0], *namePtr;
+    Tcl_Obj *scriptPtr = data[0];
     Namespace *nsPtr = data[1];
-    TEOV_record *recordPtr = TOP_RECORD(iPtr);
-    Command *cmdPtr = NULL;
 
-    if (!recordPtr->cmdPtr || recordPtr->callbackPtr) {
-	Tcl_Panic("TailcallCallback: should not happen!");
-    }
-
-    result = Tcl_ListObjIndex(interp, listPtr, 0, &namePtr);
     if (result == TCL_OK) {
-	cmdPtr = TEOV_LookupCmdFromObj(interp, namePtr, nsPtr);
+	iPtr->lookupNsPtr = nsPtr;
+	result = TclNREvalObjEx(interp, scriptPtr, 0, NULL, 0);
     }
 
     nsPtr->activationCount--;
@@ -8107,29 +7935,7 @@ TailcallCallback(
 
 	Tcl_DeleteNamespace((Tcl_Namespace *) nsPtr);
     }
-
-    if (!cmdPtr || (result != TCL_OK)) {
-	Tcl_DecrRefCount(listPtr);
-	Tcl_SetResult(interp,
-	    "the command to be tailcalled does not exist", TCL_STATIC);
-	return TCL_ERROR;
-    }
-
-    /*
-     * Take over the previous command's record.
-     */
-
-    TclCleanupCommandMacro(recordPtr->cmdPtr);
-    recordPtr->cmdPtr = cmdPtr;
-    cmdPtr->refCount++;
-
-    /*
-     * Push a new record to signal that a new command was scheduled.
-     */
-
-    PUSH_RECORD(iPtr, recordPtr);
-    iPtr->lookupNsPtr = nsPtr;
-    return TclNREvalCmd(interp, listPtr, 0);
+    return result;
 }
 
 void
@@ -8142,31 +7948,11 @@ Tcl_NRAddCallback(
     ClientData data3)
 {
     if (!(postProcPtr)) {
-	Tcl_Panic("Adding a callback without and objProc?!");
+	Tcl_Panic("Adding a callback without an objProc?!");
     }
     TclNRAddCallback(interp, postProcPtr, data0, data1, data2, data3);
 }
 
-TEOV_record *
-TclNRPushRecord(
-    Tcl_Interp *interp)
-{
-    TEOV_record *recordPtr;
-
-    PUSH_RECORD(interp, recordPtr);
-    return recordPtr;
-}
-
-void
-TclNRPopAndFreeRecord(
-    Tcl_Interp *interp)
-{
-    TEOV_record *recordPtr;
-
-    POP_RECORD(interp, recordPtr);
-    FREE_RECORD(interp, recordPtr);
-}
-
 /*
  * Local Variables:
  * mode: c
diff --git a/generic/tclCompile.h b/generic/tclCompile.h
index 63df8ce..c5ab71d 100644
--- a/generic/tclCompile.h
+++ b/generic/tclCompile.h
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclCompile.h,v 1.96 2008/07/22 22:24:21 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclCompile.h,v 1.97 2008/07/29 05:30:25 msofer Exp $
  */
 
 #ifndef _TCLCOMPILATION
@@ -830,15 +830,16 @@ typedef struct {
     } i;
 } TclOpCmdClientData;
 
+
 /*
  *----------------------------------------------------------------
  * Procedures exported by tclBasic.c to be used within the engine.
  *----------------------------------------------------------------
  */
 
-MODULE_SCOPE int	TclEvalObjvInternal(Tcl_Interp *interp,
-			    int objc, Tcl_Obj *const objv[],
-			    const char *command, int length, int flags);
+MODULE_SCOPE Tcl_NRPostProc   NRRunBytecode;
+MODULE_SCOPE Tcl_NRPostProc   NRDropCommand;
+
 /*
  *----------------------------------------------------------------
  * Procedures exported by the engine to be used by tclBasic.c
diff --git a/generic/tclDecls.h b/generic/tclDecls.h
index 138911f..1417bf9 100644
--- a/generic/tclDecls.h
+++ b/generic/tclDecls.h
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclDecls.h,v 1.143 2008/07/28 21:31:21 nijtmans Exp $
+ * RCS: @(#) $Id: tclDecls.h,v 1.144 2008/07/29 05:30:25 msofer Exp $
  */
 
 #ifndef _TCLDECLS
@@ -3517,9 +3517,16 @@ EXTERN int		Tcl_CancelEval (Tcl_Interp * interp,
 /* 581 */
 EXTERN int		Tcl_Canceled (Tcl_Interp * interp, int flags);
 #endif
+#ifndef Tcl_CreatePipe_TCL_DECLARED
+#define Tcl_CreatePipe_TCL_DECLARED
+/* 582 */
+EXTERN int		Tcl_CreatePipe (Tcl_Interp * interp, 
+				Tcl_Channel * rchan, Tcl_Channel * wchan, 
+				int flags);
+#endif
 #ifndef Tcl_NRCreateCommand_TCL_DECLARED
 #define Tcl_NRCreateCommand_TCL_DECLARED
-/* 582 */
+/* 583 */
 EXTERN Tcl_Command	Tcl_NRCreateCommand (Tcl_Interp * interp, 
 				CONST char * cmdName, Tcl_ObjCmdProc * proc, 
 				Tcl_ObjCmdProc * nreProc, 
@@ -3528,25 +3535,25 @@ EXTERN Tcl_Command	Tcl_NRCreateCommand (Tcl_Interp * interp,
 #endif
 #ifndef Tcl_NREvalObj_TCL_DECLARED
 #define Tcl_NREvalObj_TCL_DECLARED
-/* 583 */
+/* 584 */
 EXTERN int		Tcl_NREvalObj (Tcl_Interp * interp, Tcl_Obj * objPtr, 
 				int flags);
 #endif
 #ifndef Tcl_NREvalObjv_TCL_DECLARED
 #define Tcl_NREvalObjv_TCL_DECLARED
-/* 584 */
+/* 585 */
 EXTERN int		Tcl_NREvalObjv (Tcl_Interp * interp, int objc, 
 				Tcl_Obj *CONST objv[], int flags);
 #endif
 #ifndef Tcl_NRCmdSwap_TCL_DECLARED
 #define Tcl_NRCmdSwap_TCL_DECLARED
-/* 585 */
+/* 586 */
 EXTERN int		Tcl_NRCmdSwap (Tcl_Interp * interp, Tcl_Command cmd, 
-				int objc, Tcl_Obj *CONST objv[]);
+				int objc, Tcl_Obj *CONST objv[], int flags);
 #endif
 #ifndef Tcl_NRAddCallback_TCL_DECLARED
 #define Tcl_NRAddCallback_TCL_DECLARED
-/* 586 */
+/* 587 */
 EXTERN void		Tcl_NRAddCallback (Tcl_Interp * interp, 
 				Tcl_NRPostProc * postProcPtr, 
 				ClientData data0, ClientData data1, 
@@ -3554,19 +3561,12 @@ EXTERN void		Tcl_NRAddCallback (Tcl_Interp * interp,
 #endif
 #ifndef Tcl_NRCallObjProc_TCL_DECLARED
 #define Tcl_NRCallObjProc_TCL_DECLARED
-/* 587 */
+/* 588 */
 EXTERN int		Tcl_NRCallObjProc (Tcl_Interp * interp, 
 				Tcl_ObjCmdProc * objProc, 
 				ClientData clientData, int objc, 
 				Tcl_Obj *CONST objv[]);
 #endif
-#ifndef Tcl_CreatePipe_TCL_DECLARED
-#define Tcl_CreatePipe_TCL_DECLARED
-/* 588 */
-EXTERN int		Tcl_CreatePipe (Tcl_Interp * interp, 
-				Tcl_Channel * rchan, Tcl_Channel * wchan, 
-				int flags);
-#endif
 
 typedef struct TclStubHooks {
     CONST struct TclPlatStubs *tclPlatStubs;
@@ -4208,13 +4208,13 @@ typedef struct TclStubs {
     void (*tcl_AppendPrintfToObj) (Tcl_Obj * objPtr, CONST char * format, ...); /* 579 */
     int (*tcl_CancelEval) (Tcl_Interp * interp, Tcl_Obj * resultObjPtr, ClientData clientData, int flags); /* 580 */
     int (*tcl_Canceled) (Tcl_Interp * interp, int flags); /* 581 */
-    Tcl_Command (*tcl_NRCreateCommand) (Tcl_Interp * interp, CONST char * cmdName, Tcl_ObjCmdProc * proc, Tcl_ObjCmdProc * nreProc, ClientData clientData, Tcl_CmdDeleteProc * deleteProc); /* 582 */
-    int (*tcl_NREvalObj) (Tcl_Interp * interp, Tcl_Obj * objPtr, int flags); /* 583 */
-    int (*tcl_NREvalObjv) (Tcl_Interp * interp, int objc, Tcl_Obj *CONST objv[], int flags); /* 584 */
-    int (*tcl_NRCmdSwap) (Tcl_Interp * interp, Tcl_Command cmd, int objc, Tcl_Obj *CONST objv[]); /* 585 */
-    void (*tcl_NRAddCallback) (Tcl_Interp * interp, Tcl_NRPostProc * postProcPtr, ClientData data0, ClientData data1, ClientData data2, ClientData data3); /* 586 */
-    int (*tcl_NRCallObjProc) (Tcl_Interp * interp, Tcl_ObjCmdProc * objProc, ClientData clientData, int objc, Tcl_Obj *CONST objv[]); /* 587 */
-    int (*tcl_CreatePipe) (Tcl_Interp * interp, Tcl_Channel * rchan, Tcl_Channel * wchan, int flags); /* 588 */
+    int (*tcl_CreatePipe) (Tcl_Interp * interp, Tcl_Channel * rchan, Tcl_Channel * wchan, int flags); /* 582 */
+    Tcl_Command (*tcl_NRCreateCommand) (Tcl_Interp * interp, CONST char * cmdName, Tcl_ObjCmdProc * proc, Tcl_ObjCmdProc * nreProc, ClientData clientData, Tcl_CmdDeleteProc * deleteProc); /* 583 */
+    int (*tcl_NREvalObj) (Tcl_Interp * interp, Tcl_Obj * objPtr, int flags); /* 584 */
+    int (*tcl_NREvalObjv) (Tcl_Interp * interp, int objc, Tcl_Obj *CONST objv[], int flags); /* 585 */
+    int (*tcl_NRCmdSwap) (Tcl_Interp * interp, Tcl_Command cmd, int objc, Tcl_Obj *CONST objv[], int flags); /* 586 */
+    void (*tcl_NRAddCallback) (Tcl_Interp * interp, Tcl_NRPostProc * postProcPtr, ClientData data0, ClientData data1, ClientData data2, ClientData data3); /* 587 */
+    int (*tcl_NRCallObjProc) (Tcl_Interp * interp, Tcl_ObjCmdProc * objProc, ClientData clientData, int objc, Tcl_Obj *CONST objv[]); /* 588 */
 } TclStubs;
 
 #if defined(USE_TCL_STUBS) && !defined(USE_TCL_STUB_PROCS)
@@ -6615,33 +6615,33 @@ extern CONST TclStubs *tclStubsPtr;
 #define Tcl_Canceled \
 	(tclStubsPtr->tcl_Canceled) /* 581 */
 #endif
+#ifndef Tcl_CreatePipe
+#define Tcl_CreatePipe \
+	(tclStubsPtr->tcl_CreatePipe) /* 582 */
+#endif
 #ifndef Tcl_NRCreateCommand
 #define Tcl_NRCreateCommand \
-	(tclStubsPtr->tcl_NRCreateCommand) /* 582 */
+	(tclStubsPtr->tcl_NRCreateCommand) /* 583 */
 #endif
 #ifndef Tcl_NREvalObj
 #define Tcl_NREvalObj \
-	(tclStubsPtr->tcl_NREvalObj) /* 583 */
+	(tclStubsPtr->tcl_NREvalObj) /* 584 */
 #endif
 #ifndef Tcl_NREvalObjv
 #define Tcl_NREvalObjv \
-	(tclStubsPtr->tcl_NREvalObjv) /* 584 */
+	(tclStubsPtr->tcl_NREvalObjv) /* 585 */
 #endif
 #ifndef Tcl_NRCmdSwap
 #define Tcl_NRCmdSwap \
-	(tclStubsPtr->tcl_NRCmdSwap) /* 585 */
+	(tclStubsPtr->tcl_NRCmdSwap) /* 586 */
 #endif
 #ifndef Tcl_NRAddCallback
 #define Tcl_NRAddCallback \
-	(tclStubsPtr->tcl_NRAddCallback) /* 586 */
+	(tclStubsPtr->tcl_NRAddCallback) /* 587 */
 #endif
 #ifndef Tcl_NRCallObjProc
 #define Tcl_NRCallObjProc \
-	(tclStubsPtr->tcl_NRCallObjProc) /* 587 */
-#endif
-#ifndef Tcl_CreatePipe
-#define Tcl_CreatePipe \
-	(tclStubsPtr->tcl_CreatePipe) /* 588 */
+	(tclStubsPtr->tcl_NRCallObjProc) /* 588 */
 #endif
 
 #endif /* defined(USE_TCL_STUBS) && !defined(USE_TCL_STUB_PROCS) */
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 0102f5a..0aee386 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -14,7 +14,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclExecute.c,v 1.387 2008/07/22 21:41:55 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.388 2008/07/29 05:30:26 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -166,27 +166,26 @@ static BuiltinFunc tclBuiltinFuncTable[] = {
 /*
  * NR_TEBC
  * Helpers for NR - non-recursive calls to TEBC
+ * Minimal data required to fully reconstruct the execution state.
  */
 
 typedef struct BottomData {
-#if USE_NR_TEBC
     struct BottomData *prevBottomPtr;
-    TEOV_record *recordPtr;      /* Top record on TEOVI's cleanup stack when
-				  * this level was entered.                   */
-    ByteCode *codePtr;           /* The following data is used on return      */
-    unsigned char *pc;           /* TO this level: they record the state when */
-    ptrdiff_t *catchTop;         /* a new codePtr was received for NR         */
-    int cleanup;     		 /* execution.                                */ 
+    TEOV_callback *rootPtr;      /* State when this bytecode execution began. */
+    ByteCode *codePtr;		 /* These fields remain constant until it     */
+    CmdFrame *cmdFramePtr;       /* returns.                                  */
+                                 /* ------------------------------------------*/
+    unsigned char *pc;           /* These fields are used on return TO this   */
+    ptrdiff_t *catchTop;         /* this level: they record the state when  a */
+    int cleanup;     		 /* new codePtr was received for NR execution */
     Tcl_Obj *auxObjList;
-#endif
 } BottomData;
 
-#if USE_NR_TEBC
-
-#define NR_DATA_INIT()			        \
+#define NR_DATA_INIT()				\
     bottomPtr->prevBottomPtr = oldBottomPtr;	\
-    bottomPtr->recordPtr = TOP_RECORD(iPtr);	\
-    bottomPtr->codePtr = codePtr
+    bottomPtr->rootPtr = TOP_CB(iPtr);	\
+    bottomPtr->codePtr = codePtr;	\
+    bottomPtr->cmdFramePtr = iPtr->cmdFramePtr
 
 #define NR_DATA_BURY()				\
     bottomPtr->pc = pc;				\
@@ -201,12 +200,13 @@ typedef struct BottomData {
     catchTop = bottomPtr->catchTop;			\
     cleanup = bottomPtr->cleanup;			\
     auxObjList = bottomPtr->auxObjList;			\
-    iPtr->cmdFramePtr = iPtr->cmdFramePtr->nextPtr
-#endif
+    esPtr = iPtr->execEnvPtr->execStackPtr;		\
+    tosPtr = esPtr->tosPtr;				\
+    iPtr->cmdFramePtr = bottomPtr->cmdFramePtr; 
 
 #define PUSH_AUX_OBJ(objPtr)					\
     objPtr->internalRep.twoPtrValue.ptr2 = auxObjList;		\
-    auxObjList = objPtr  
+    auxObjList = objPtr
 
 #define POP_AUX_OBJ()							\
     {									\
@@ -799,8 +799,7 @@ TclCreateExecEnv(
     Tcl_IncrRefCount(eePtr->constants[0]);
     TclNewBooleanObj(eePtr->constants[1], 1);
     Tcl_IncrRefCount(eePtr->constants[1]);
-    eePtr->recordPtr = NULL;
-    eePtr->tebcCall = 0;
+    eePtr->callbackPtr = NULL;
 
     esPtr->prevPtr = NULL;
     esPtr->nextPtr = NULL;
@@ -875,7 +874,7 @@ TclDeleteExecEnv(
 
     TclDecrRefCount(eePtr->constants[0]);
     TclDecrRefCount(eePtr->constants[1]);
-    if (eePtr->recordPtr) {
+    if (eePtr->callbackPtr) {
 	Tcl_Panic("Deleting execEnv with pending TEOV callbacks!");
     }
     ckfree((char *) eePtr);
@@ -1473,7 +1472,7 @@ FreeExprCodeInternalRep(
  *	This procedure compiles the script contained in a Tcl_Obj 
  *
  * Results:
- *	A pointer to the corresponding ByteCode
+ *	A pointer to the corresponding ByteCode, never NULL.
  *
  * Side effects:
  *	The object is shimmered to bytecode type
@@ -1752,9 +1751,7 @@ TclExecuteByteCode(
     /* NR_TEBC */
 
     BottomData *bottomPtr;
-#if USE_NR_TEBC
     BottomData *oldBottomPtr = NULL;
-#endif
     
     /*
      * Constants: variables that do not change during the execution, used
@@ -1793,10 +1790,7 @@ TclExecuteByteCode(
 
     register int cleanup;
     Tcl_Obj *objResultPtr;
-    int evalFlags = TCL_EVAL_NOERR;
-#if (USE_NR_TEBC)
-    int tailcall = 0;
-#endif    
+
     /*
      * Result variable - needed only when going to checkForcatch or other
      * error handlers; also used as local in some opcodes.
@@ -1826,13 +1820,47 @@ TclExecuteByteCode(
      * execution stack is large enough to execute this ByteCode.
      */
 
-    /*
-     * NR_TEBC
-     */
+    int nested = 0;
     
-#if USE_NR_TEBC
     nonRecursiveCallStart:
+    if (nested) {
+	TEOV_callback *callbackPtr = TOP_CB(interp);
+	Tcl_NRPostProc *procPtr = callbackPtr->procPtr;
+	ByteCode *newCodePtr = callbackPtr->data[0];
+
+	assert((result==TCL_OK));
+	assert((callbackPtr != bottomPtr->rootPtr));	
+
+	TOP_CB(interp) = callbackPtr->nextPtr;
+	TCLNR_FREE(interp, callbackPtr);
+
+	if (procPtr == NRRunBytecode) {
+	    NR_DATA_BURY(); /* this level's state variables */
+	    codePtr = newCodePtr;
+	} else if (procPtr == NRDropCommand) {
+	    /*
+	     * A request to perform a tailcall: just drop this
+	     * bytecode as it is; the tailCall has been scheduled in
+	     * the callbacks.
+	     */
+#ifdef TCL_COMPILE_DEBUG
+	    if (traceInstructions) {
+		fprintf(stdout, "   Tailcall: request received\n");
+	    }
 #endif
+	    if (catchTop != initCatchTop) {
+		result = TCL_ERROR;
+		Tcl_SetResult(interp,"Tailcall called from within a catch environment",
+			TCL_STATIC);
+		goto checkForCatch;
+	    }
+	    goto abnormalReturn; /* drop a level */
+	} else {
+	    Tcl_Panic("TEBC: TRCB sent us a record we cannot handle! (1)");
+	}
+    }
+    nested = 1;
+    
     codePtr->refCount++;
     bottomPtr = (BottomData *) GrowEvaluationStack(iPtr->execEnvPtr,
 	    sizeof(BottomData) + codePtr->maxExceptDepth + sizeof(CmdFrame)
@@ -1840,12 +1868,9 @@ TclExecuteByteCode(
     curInstName = NULL;
     auxObjList = NULL;
     initLevel = 1;
-    
-#if USE_NR_TEBC
     NR_DATA_INIT(); /* record this level's data */
-    
+
     nonRecursiveCallReturn:  
-#endif
     bcFramePtr = (CmdFrame *) (bottomPtr + 1);
     initCatchTop = ((ptrdiff_t *) (bcFramePtr + 1)) - 1;
     initTosPtr = (Tcl_Obj **) (initCatchTop + codePtr->maxExceptDepth);
@@ -1880,10 +1905,6 @@ TclExecuteByteCode(
 
 	TclArgumentBCEnter((Tcl_Interp*) iPtr,codePtr,bcFramePtr);
 
-#if (USE_NR_TEBC)
-    } else if (tailcall) {
-	    goto tailcallEntry;	    
-#endif
     } else {
 	/*
 	 * Returning from a non-recursive call. State is already completely
@@ -2475,6 +2496,25 @@ TclExecuteByteCode(
 	NEXT_INST_F(5, 0, 0);
     }
 
+    case INST_EXPR_STK: {
+	/*
+	 * Moved here to support transforming the eval of an expression to
+	 * a non-recursive TEBC call.
+	 */
+	
+	ByteCode *newCodePtr;
+	
+	bcFramePtr->data.tebc.pc = (char *) pc;
+	iPtr->cmdFramePtr = bcFramePtr;	    
+	DECACHE_STACK_INFO();
+	newCodePtr = CompileExprObj(interp, OBJ_AT_TOS);
+	CACHE_STACK_INFO();
+	cleanup = 1;
+	pc++;
+	Tcl_NRAddCallback(interp, NRRunBytecode, newCodePtr, NULL, NULL, NULL);
+	goto nonRecursiveCallStart;
+    }
+
     {
 	/*
 	 * INVOCATION BLOCK
@@ -2482,70 +2522,7 @@ TclExecuteByteCode(
 
 	int objc, pcAdjustment;
 	Tcl_Obj **objv;
-#if (USE_NR_TEBC)
-	TEOV_record *recordPtr;
-	ByteCode *newCodePtr;
-#endif
 	
-	case INST_EXPR_STK: {
-	    /*
-	     * Moved here to support transforming the eval of an expression to
-	     * a non-recursive TEBC call.
-	     */
-
-#if (USE_NR_TEBC)
-	    pcAdjustment = 1;
-	    cleanup = 1;
-	    bcFramePtr->data.tebc.pc = (char *) pc;
-	    iPtr->cmdFramePtr = bcFramePtr;	    
-	    DECACHE_STACK_INFO();
-	    newCodePtr = CompileExprObj(interp, OBJ_AT_TOS);
-	    CACHE_STACK_INFO();
-	    goto tebc_do_exec;
-#else
-	    Tcl_Obj *objPtr, *valuePtr;
-
-	    objPtr = OBJ_AT_TOS;
-
-	    DECACHE_STACK_INFO();
-	    /*Tcl_ResetResult(interp);*/
-	    result = Tcl_ExprObj(interp, objPtr, &valuePtr);
-	    CACHE_STACK_INFO();
-	    if (result == TCL_OK) {
-		objResultPtr = valuePtr;
-		TRACE_WITH_OBJ(("\"%.30s\" => ", O2S(objPtr)), valuePtr);
-		NEXT_INST_F(1, 1, -1);	/* Already has right refct. */
-	    } else {
-		TRACE_WITH_OBJ(("\"%.30s\" => ERROR: ", O2S(objPtr)),
-			Tcl_GetObjResult(interp));
-		cleanup = 1;
-		goto checkForCatch;
-	    }
-#endif
-	}
-
-#if (USE_NR_TEBC)
-	tailcallEntry: {
-	    TEOV_record *recordPtr = TOP_RECORD(iPtr);
-
-	    /*
-	     * We take over the record's object, with its refCount. Clear the
-	     * record type so that it is not freed again when popping the
-	     * record. 
-	     */
-	    
-	    recordPtr->type = TCL_NR_NO_TYPE;
-	    *++tosPtr = recordPtr->data.obj.objPtr;
-	    evalFlags = recordPtr->data.obj.flags;
-	    recordPtr->type = TCL_NR_NO_TYPE;
-#ifdef TCL_COMPILE_DEBUG
-		if (traceInstructions) {
-		    fprintf(stdout, "   Tailcall: pushing obj with refCount %i\n",
-			    (OBJ_AT_TOS)->refCount);
-		}
-#endif
-	}
-#endif
 	case INST_EVAL_STK: {
 	    /*
 	     * Moved here to support transforming the eval of objects to a
@@ -2554,10 +2531,10 @@ TclExecuteByteCode(
 	     */
 	    
 	    Tcl_Obj *objPtr = OBJ_AT_TOS;
+	    ByteCode *newCodePtr;
 
 	    cleanup = 1;
-	    pcAdjustment = !tailcall;
-	    tailcall = 0;
+	    pcAdjustment = 1;
 		
 	    if (objPtr->typePtr == &tclListType) {	/* is a list... */
 		List *listRepPtr = objPtr->internalRep.twoPtrValue.ptr1;
@@ -2580,59 +2557,20 @@ TclExecuteByteCode(
 	    }
 	    
 	    /*
+	     * Run the bytecode in this same TEBC instance!
+	     *
 	     * TIP #280: The invoking context is left NULL for a dynamically
 	     * constructed command. We cannot match its lines to the outer
 	     * context.
-	     */	    
+	     */
 	    
 	    DECACHE_STACK_INFO();
 	    newCodePtr = TclCompileObj(interp, objPtr, NULL, 0);
-	    if (newCodePtr) {
-		/*
-		 * Run the bytecode in this same TEBC instance!
-		 */
-#if (USE_NR_TEBC)
-		bcFramePtr->data.tebc.pc = (char *) pc;
-		iPtr->cmdFramePtr = bcFramePtr;
-		goto tebc_do_exec;
-#else
-		result = TclExecuteByteCode(interp, newCodePtr);
-		CACHE_STACK_INFO();
-		
-		if (result == TCL_OK) {
-		    /*
-		     * Normal return; push the eval's object result.
-		     */
-		    
-		    objResultPtr = Tcl_GetObjResult(interp);
-		    TRACE_WITH_OBJ(("\"%.30s\" => ", O2S(objPtr)),
-			    Tcl_GetObjResult(interp));
-		    
-		    /*
-		     * Reset the interp's result to avoid possible duplications of
-		     * large objects [Bug 781585]. We do not call Tcl_ResetResult to
-		     * avoid any side effects caused by the resetting of errorInfo and
-		     * errorCode [Bug 804681], which are not needed here. We chose
-		     * instead to manipulate the interp's object result directly.
-		     *
-		     * Note that the result object is now in objResultPtr, it keeps
-		     * the refCount it had in its role of iPtr->objResultPtr.
-		     */
-		    
-		    TclNewObj(objPtr);
-		    Tcl_IncrRefCount(objPtr);
-		    iPtr->objResultPtr = objPtr;
-		    NEXT_INST_F(1, 1, -1);
-		}
-#endif
-	    }
-	    
-	    /*
-	     * Compilation failed, error
-	     */
-	    
-	    result = TCL_ERROR;
-	    goto processExceptionReturn;
+	    bcFramePtr->data.tebc.pc = (char *) pc;
+	    iPtr->cmdFramePtr = bcFramePtr;
+	    pc++;
+	    Tcl_NRAddCallback(interp, NRRunBytecode, newCodePtr, NULL, NULL, NULL);
+	    goto nonRecursiveCallStart;
 	}
 
     case INST_INVOKE_EXPANDED:
@@ -2708,55 +2646,17 @@ TclExecuteByteCode(
 
 	    DECACHE_STACK_INFO();
 
-#if (USE_NR_TEBC)
-	    TEBC_CALL(iPtr) = 1;
-	    recordPtr = TOP_RECORD(iPtr);
-#endif
-	    result = TclEvalObjv(interp, objc, objv, evalFlags, NULL);
+	    result = TclNREvalObjv(interp, objc, objv, TCL_EVAL_NOERR, NULL);
+	    result = TclNRRunCallbacks(interp, result, bottomPtr->rootPtr, 1);
 	    CACHE_STACK_INFO();
-#if (USE_NR_TEBC)
-	    evalFlags = TCL_EVAL_NOERR;
-	    if (TOP_RECORD(iPtr) != recordPtr) {
-		assert((result == TCL_OK));
-		recordPtr = TOP_RECORD(iPtr);
-		switch(recordPtr->type) {
-		case TCL_NR_BC_TYPE:
-		    newCodePtr = recordPtr->data.codePtr;
-		tebc_do_exec:
-		    /*
-		     * A request to execute a bytecode came back. We save
-		     * the current state and restart at the top.
-		     */
 
-		    pc += pcAdjustment;
-		    NR_DATA_BURY(); /* this level's state variables */
-		    codePtr = newCodePtr;
-		    goto nonRecursiveCallStart;
-		case TCL_NR_TAILCALL_TYPE:
-		    /*
-		     * A request to perform a tailcall: just drop this
-		     * bytecode as it is; the tailCall has been scheduled in
-		     * the callbacks.
-		     */
-#ifdef TCL_COMPILE_DEBUG
-		    if (traceInstructions) {
-			fprintf(stdout, "   Tailcall: request received\n");
-		    }
-#endif
-		    if (catchTop != initCatchTop) {
-			result = TCL_ERROR;
-			Tcl_SetResult(interp,"Tailcall called from within a catch environment",
-				TCL_STATIC);
-			goto checkForCatch;
-		    }
-		    goto abnormalReturn; /* drop a level */
-		default:
-		    Tcl_Panic("TEBC: TEOV sent us a record we cannot handle!");
-		}
+	    if (TOP_CB(interp) != bottomPtr->rootPtr) {
+		assert ((result == TCL_OK));
+		pc += pcAdjustment;		
+		goto nonRecursiveCallStart;
 	    }
-#endif
 	    iPtr->cmdFramePtr = iPtr->cmdFramePtr->nextPtr;
-
+	    
 	    if (result == TCL_OK) {
 		Tcl_Obj *objPtr;
 #ifndef TCL_COMPILE_DEBUG
@@ -7762,81 +7662,64 @@ TclExecuteByteCode(
 
     TclArgumentBCRelease((Tcl_Interp*) iPtr,codePtr);
 
-#if USE_NR_TEBC
     oldBottomPtr = bottomPtr->prevBottomPtr;
-#endif
     TclStackFree(interp, bottomPtr);     /* free my stack */
 
     if (--codePtr->refCount <= 0) {
 	TclCleanupByteCode(codePtr);
     }
 
-#if USE_NR_TEBC
     if (oldBottomPtr) {
 	/*
 	 * Restore the state to what it was previous to this bytecode.
-	 *
-	 * NR_TEBC
 	 */
-	bottomPtr = oldBottomPtr;        /* back to old bc */
+
+	bottomPtr = oldBottomPtr;        /* back to old bc */	
+	result = TclNRRunCallbacks(interp, result, bottomPtr->rootPtr, 1);
 	
-	/* Please free anything that might still be on my new stack */
-      resumeCleanup:
-	if (TOP_RECORD(iPtr) != bottomPtr->recordPtr) {
-	    CACHE_STACK_INFO();
-	    result = TclEvalObjv_NR2(interp, result, bottomPtr->recordPtr);
-	    if (TOP_RECORD(iPtr) != bottomPtr->recordPtr) {
-		TEOV_record *recordPtr = TOP_RECORD(iPtr);
+	NR_DATA_DIG();
+	DECACHE_STACK_INFO();
+	if (TOP_CB(interp) == bottomPtr->rootPtr) {
+	    /*
+	     * The bytecode is returning, remove the caller's arguments and
+	     * keep processing the caller.
+	     */
+	    
+	    while (cleanup--) {
+		Tcl_Obj *objPtr = POP_OBJECT();
+		Tcl_DecrRefCount(objPtr);
+	    }
+	    goto nonRecursiveCallReturn;
+	} else {
+	    /*
+	     * A request for a new execution: a tailcall. Remove the caller's
+	     * arguments and start the new bytecode.
+	     *
+	     * FIXME KNOWNBUG: we get a pointer smash if we do remove the
+	     * arguments, a leak otherwise: tailcalls are not yet quite
+	     * there. Chose to leave the leak for now.
+	     */
 		
-		assert((result == TCL_OK));
-
-		/*
-		 * A callback scheduled a new evaluation: process it.
-		 */
-
-		switch(recordPtr->type) {
-		    case TCL_NR_BC_TYPE:
-			codePtr = recordPtr->data.codePtr;
-			goto nonRecursiveCallStart;
-		    case TCL_NR_TAILCALL_TYPE:
-			/* FIXME NRE tailcall*/			
-			Tcl_Panic("Tailcall called from a callback!");
-			NR_DATA_DIG();
-			esPtr = iPtr->execEnvPtr->execStackPtr;
-			goto abnormalReturn; /* drop a level */
-		    case TCL_NR_CMD_TYPE: 
-		    case TCL_NR_SCRIPT_TYPE:
-			/*
-			 * FIXME NRE tailcall: error messages will be all wrong?
-			 */
-#ifdef TCL_COMPILE_DEBUG
-			if (traceInstructions) {
-			    fprintf(stdout, "   Tailcall: eval request received from callback\n");
-			}
-#endif
-			tailcall = 1;
-			goto restoreStateVariables;
-		    case TCL_NR_CMDSWAP_TYPE:
-			result = TclEvalObjv(interp, recordPtr->data.objcv.objc,
-				recordPtr->data.objcv.objv, 0, recordPtr->cmdPtr);
-			goto resumeCleanup;
-		    default:
-			Tcl_Panic("TEBC: TEOV_NR2 sent us a record we cannot handle!");
+	    TEOV_callback *callbackPtr = TOP_CB(interp);
+	    Tcl_NRPostProc *procPtr = callbackPtr->procPtr;
+
+	    if (procPtr == NRRunBytecode) {
+		goto nonRecursiveCallStart;
+	    } else if (procPtr == NRDropCommand) {
+		/* FIXME: 'tailcall tailcall' not yet working */
+		Tcl_Panic("Tailcalls from within tailcalls are not yet implemented");
+		if (catchTop != initCatchTop) {
+		    result = TCL_ERROR;
+		    Tcl_SetResult(interp,"Tailcall called from within a catch environment",
+			    TCL_STATIC);
+		    goto checkForCatch;
 		}
+		goto abnormalReturn; /* drop a level */
+	    } else {
+		Tcl_Panic("TEBC: TEOV sent us a record we cannot handle! (2)");		
 	    }
 	}
-      restoreStateVariables:
-	NR_DATA_DIG();
-	esPtr = iPtr->execEnvPtr->execStackPtr;
-	tosPtr = esPtr->tosPtr;
-	while (cleanup--) {
-	    Tcl_Obj *objPtr = POP_OBJECT();
-	    Tcl_DecrRefCount(objPtr);
-	}
-	CACHE_STACK_INFO();
-	goto nonRecursiveCallReturn;
     }
-#endif
     return result;
 }
 #undef iPtr
diff --git a/generic/tclInt.decls b/generic/tclInt.decls
index e1e46d0..8213109 100644
--- a/generic/tclInt.decls
+++ b/generic/tclInt.decls
@@ -13,7 +13,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: tclInt.decls,v 1.126 2008/07/24 22:57:57 nijtmans Exp $
+# RCS: @(#) $Id: tclInt.decls,v 1.127 2008/07/29 05:30:32 msofer Exp $
 
 library tcl
 
@@ -894,10 +894,12 @@ declare 227 generic {
     void TclSetNsPath(Namespace *nsPtr, int pathLength,
             Tcl_Namespace *pathAry[])
 }
-declare 228 generic {
-    int TclObjInterpProcCore(register Tcl_Interp *interp, Tcl_Obj *procNameObj,
-             int skip, ProcErrorProc errorProc)
-}
+#  Used to be needed for TclOO-extension; unneeded now that TclOO is in the
+#  core and NRE-enabled
+#  declare 228 generic {
+#      int TclObjInterpProcCore(register Tcl_Interp *interp, Tcl_Obj *procNameObj,
+#             int skip, ProcErrorProc errorProc)
+#  }
 declare 229 generic {
     int	TclPtrMakeUpvar(Tcl_Interp *interp, Var *otherP1Ptr,
 	    CONST char *myName, int myFlags, int index)
@@ -943,28 +945,25 @@ declare 237 generic {
 # NRE functions for "rogue" extensions to exploit NRE; they will need to
 # include NRE.h too.
 declare 238 generic {
-    int TclEvalObjv_NR2(Tcl_Interp *interp, int result,
-			struct TEOV_record *rootPtr)
-}
-declare 239 generic {
     int TclNRInterpProc(ClientData clientData, Tcl_Interp *interp,
 	    int objc, Tcl_Obj *CONST objv[])
 }
-declare 240 generic {
+declare 239 generic {
     int TclNRInterpProcCore(Tcl_Interp *interp, Tcl_Obj *procNameObj,
 			    int skip, ProcErrorProc errorProc)
 }
-declare 241 generic {
-    struct TEOV_record * TclNRPushRecord(Tcl_Interp *interp)
-}
-declare 242 generic {
-    void TclNRPopAndFreeRecord(Tcl_Interp *interp)
+declare 240 generic {
+    int TclNRRunCallbacks(Tcl_Interp * interp, int result,
+	      struct TEOV_callback * rootPtr, int tebcCall)
 }
-
-declare 243 generic {
+declare 241 generic {
     int TclNREvalObjEx(Tcl_Interp *interp, Tcl_Obj *objPtr, int flags,
 	    CONST CmdFrame *invoker, int word)
 }
+declare 242 generic {
+    int TclNREvalObjv(Tcl_Interp *interp, int objc,
+	      Tcl_Obj *const objv[], int flags, Command *cmdPtr)
+}
 ##############################################################################
 
 # Define the platform specific internal Tcl interface. These functions are
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 0587ecf..1b10fc6 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -14,7 +14,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclInt.h,v 1.379 2008/07/24 22:57:55 nijtmans Exp $
+ * RCS: @(#) $Id: tclInt.h,v 1.380 2008/07/29 05:30:32 msofer Exp $
  */
 
 #ifndef _TCLINT
@@ -1329,17 +1329,13 @@ typedef struct ExecStack {
  * currently active execution stack.
  */
 
-struct TEOV_record;
-
 typedef struct ExecEnv {
     ExecStack *execStackPtr;	    /* Points to the first item in the
 				     * evaluation stack on the heap. */
     Tcl_Obj *constants[2];	    /* Pointers to constant "0" and "1"
-				     * objs. */
-    struct TEOV_record *recordPtr;  /* Top record in TEOV's stack */
-    int tebcCall;                   /* used to distinguish tebc calls from
-				     * other calls to TEOV, and other comms
-				     * between TEBC and TEOV */
+				     * objs. */ 
+    struct TEOV_callback *callbackPtr;
+                                    /* Top callback in TEOV's stack */
 } ExecEnv;
 
 /*
@@ -2516,10 +2512,12 @@ MODULE_SCOPE char	tclEmptyString;
 
 /* Introduced by/for NRE */
 MODULE_SCOPE Tcl_ObjCmdProc TclNRNamespaceObjCmd;
+MODULE_SCOPE Tcl_ObjCmdProc TclNRApplyObjCmd;
+MODULE_SCOPE Tcl_ObjCmdProc TclNRUplevelObjCmd;
 MODULE_SCOPE int        TclNREvalCmd(Tcl_Interp * interp, Tcl_Obj * objPtr,
 	                    int flags);
-MODULE_SCOPE int        TclEvalObjv(Tcl_Interp *interp, int objc,
-	                    Tcl_Obj *const objv[], int flags, Command *cmdPtr);
+
+MODULE_SCOPE void       TclNRClearCommandFlag(Tcl_Interp *interp);
 
 MODULE_SCOPE void       TclAdvanceLines(int *line, const char *start,
 			    const char *end);
@@ -2789,8 +2787,8 @@ MODULE_SCOPE Tcl_Obj *	TclDisassembleByteCodeObj(Tcl_Obj *objPtr);
 MODULE_SCOPE void *     TclpThreadCreateKey(void);
 MODULE_SCOPE void       TclpThreadDeleteKey(void *keyPtr);
 MODULE_SCOPE void       TclpThreadSetMasterTSD(void *tsdKeyPtr, void *ptr);
-MODULE_SCOPE void *     TclpThreadGetMasterTSD(void *tsdKeyPtr);
-
+MODULE_SCOPE void *     TclpThreadGetMasterTSD(void *tsdKeyPtr); 
+  
 /*
  *----------------------------------------------------------------
  * Command procedures in the generic core:
@@ -4011,7 +4009,7 @@ MODULE_SCOPE void	TclBNInitBignumFromWideUInt(mp_int *bignum,
 #include "tclTomMathDecls.h"
 
 #endif /* _TCLINT */
-
+
 /*
  * Local Variables:
  * mode: c
diff --git a/generic/tclIntDecls.h b/generic/tclIntDecls.h
index 0ef9eef..2148ab6 100644
--- a/generic/tclIntDecls.h
+++ b/generic/tclIntDecls.h
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclIntDecls.h,v 1.122 2008/07/24 22:57:54 nijtmans Exp $
+ * RCS: @(#) $Id: tclIntDecls.h,v 1.123 2008/07/29 05:30:34 msofer Exp $
  */
 
 #ifndef _TCLINTDECLS
@@ -1012,13 +1012,7 @@ EXTERN int		TclObjBeingDeleted (Tcl_Obj * objPtr);
 EXTERN void		TclSetNsPath (Namespace * nsPtr, int pathLength, 
 				Tcl_Namespace * pathAry[]);
 #endif
-#ifndef TclObjInterpProcCore_TCL_DECLARED
-#define TclObjInterpProcCore_TCL_DECLARED
-/* 228 */
-EXTERN int		TclObjInterpProcCore (register Tcl_Interp * interp, 
-				Tcl_Obj * procNameObj, int skip, 
-				ProcErrorProc errorProc);
-#endif
+/* Slot 228 is reserved */
 #ifndef TclPtrMakeUpvar_TCL_DECLARED
 #define TclPtrMakeUpvar_TCL_DECLARED
 /* 229 */
@@ -1076,43 +1070,40 @@ EXTERN void		TclBackgroundException (Tcl_Interp * interp,
 /* 237 */
 EXTERN int		TclResetCancellation (Tcl_Interp * interp, int force);
 #endif
-#ifndef TclEvalObjv_NR2_TCL_DECLARED
-#define TclEvalObjv_NR2_TCL_DECLARED
-/* 238 */
-EXTERN int		TclEvalObjv_NR2 (Tcl_Interp * interp, int result, 
-				struct TEOV_record * rootPtr);
-#endif
 #ifndef TclNRInterpProc_TCL_DECLARED
 #define TclNRInterpProc_TCL_DECLARED
-/* 239 */
+/* 238 */
 EXTERN int		TclNRInterpProc (ClientData clientData, 
 				Tcl_Interp * interp, int objc, 
 				Tcl_Obj *CONST objv[]);
 #endif
 #ifndef TclNRInterpProcCore_TCL_DECLARED
 #define TclNRInterpProcCore_TCL_DECLARED
-/* 240 */
+/* 239 */
 EXTERN int		TclNRInterpProcCore (Tcl_Interp * interp, 
 				Tcl_Obj * procNameObj, int skip, 
 				ProcErrorProc errorProc);
 #endif
-#ifndef TclNRPushRecord_TCL_DECLARED
-#define TclNRPushRecord_TCL_DECLARED
-/* 241 */
-EXTERN struct TEOV_record * TclNRPushRecord (Tcl_Interp * interp);
-#endif
-#ifndef TclNRPopAndFreeRecord_TCL_DECLARED
-#define TclNRPopAndFreeRecord_TCL_DECLARED
-/* 242 */
-EXTERN void		TclNRPopAndFreeRecord (Tcl_Interp * interp);
+#ifndef TclNRRunCallbacks_TCL_DECLARED
+#define TclNRRunCallbacks_TCL_DECLARED
+/* 240 */
+EXTERN int		TclNRRunCallbacks (Tcl_Interp * interp, int result, 
+				struct TEOV_callback * rootPtr, int tebcCall);
 #endif
 #ifndef TclNREvalObjEx_TCL_DECLARED
 #define TclNREvalObjEx_TCL_DECLARED
-/* 243 */
+/* 241 */
 EXTERN int		TclNREvalObjEx (Tcl_Interp * interp, 
 				Tcl_Obj * objPtr, int flags, 
 				CONST CmdFrame * invoker, int word);
 #endif
+#ifndef TclNREvalObjv_TCL_DECLARED
+#define TclNREvalObjv_TCL_DECLARED
+/* 242 */
+EXTERN int		TclNREvalObjv (Tcl_Interp * interp, int objc, 
+				Tcl_Obj *const objv[], int flags, 
+				Command * cmdPtr);
+#endif
 
 typedef struct TclIntStubs {
     int magic;
@@ -1370,7 +1361,7 @@ typedef struct TclIntStubs {
     Tcl_Obj * (*tclTraceDictPath) (Tcl_Interp * interp, Tcl_Obj * rootPtr, int keyc, Tcl_Obj *CONST keyv[], int flags); /* 225 */
     int (*tclObjBeingDeleted) (Tcl_Obj * objPtr); /* 226 */
     void (*tclSetNsPath) (Namespace * nsPtr, int pathLength, Tcl_Namespace * pathAry[]); /* 227 */
-    int (*tclObjInterpProcCore) (register Tcl_Interp * interp, Tcl_Obj * procNameObj, int skip, ProcErrorProc errorProc); /* 228 */
+    void *reserved228;
     int (*tclPtrMakeUpvar) (Tcl_Interp * interp, Var * otherP1Ptr, CONST char * myName, int myFlags, int index); /* 229 */
     Var * (*tclObjLookupVar) (Tcl_Interp * interp, Tcl_Obj * part1Ptr, CONST char * part2, int flags, CONST char * msg, CONST int createPart1, CONST int createPart2, Var ** arrayPtrPtr); /* 230 */
     int (*tclGetNamespaceFromObj) (Tcl_Interp * interp, Tcl_Obj * objPtr, Tcl_Namespace ** nsPtrPtr); /* 231 */
@@ -1380,12 +1371,11 @@ typedef struct TclIntStubs {
     void (*tclInitVarHashTable) (TclVarHashTable * tablePtr, Namespace * nsPtr); /* 235 */
     void (*tclBackgroundException) (Tcl_Interp * interp, int code); /* 236 */
     int (*tclResetCancellation) (Tcl_Interp * interp, int force); /* 237 */
-    int (*tclEvalObjv_NR2) (Tcl_Interp * interp, int result, struct TEOV_record * rootPtr); /* 238 */
-    int (*tclNRInterpProc) (ClientData clientData, Tcl_Interp * interp, int objc, Tcl_Obj *CONST objv[]); /* 239 */
-    int (*tclNRInterpProcCore) (Tcl_Interp * interp, Tcl_Obj * procNameObj, int skip, ProcErrorProc errorProc); /* 240 */
-    struct TEOV_record * (*tclNRPushRecord) (Tcl_Interp * interp); /* 241 */
-    void (*tclNRPopAndFreeRecord) (Tcl_Interp * interp); /* 242 */
-    int (*tclNREvalObjEx) (Tcl_Interp * interp, Tcl_Obj * objPtr, int flags, CONST CmdFrame * invoker, int word); /* 243 */
+    int (*tclNRInterpProc) (ClientData clientData, Tcl_Interp * interp, int objc, Tcl_Obj *CONST objv[]); /* 238 */
+    int (*tclNRInterpProcCore) (Tcl_Interp * interp, Tcl_Obj * procNameObj, int skip, ProcErrorProc errorProc); /* 239 */
+    int (*tclNRRunCallbacks) (Tcl_Interp * interp, int result, struct TEOV_callback * rootPtr, int tebcCall); /* 240 */
+    int (*tclNREvalObjEx) (Tcl_Interp * interp, Tcl_Obj * objPtr, int flags, CONST CmdFrame * invoker, int word); /* 241 */
+    int (*tclNREvalObjv) (Tcl_Interp * interp, int objc, Tcl_Obj *const objv[], int flags, Command * cmdPtr); /* 242 */
 } TclIntStubs;
 
 #if defined(USE_TCL_STUBS) && !defined(USE_TCL_STUB_PROCS)
@@ -2091,10 +2081,7 @@ extern CONST TclIntStubs *tclIntStubsPtr;
 #define TclSetNsPath \
 	(tclIntStubsPtr->tclSetNsPath) /* 227 */
 #endif
-#ifndef TclObjInterpProcCore
-#define TclObjInterpProcCore \
-	(tclIntStubsPtr->tclObjInterpProcCore) /* 228 */
-#endif
+/* Slot 228 is reserved */
 #ifndef TclPtrMakeUpvar
 #define TclPtrMakeUpvar \
 	(tclIntStubsPtr->tclPtrMakeUpvar) /* 229 */
@@ -2131,29 +2118,25 @@ extern CONST TclIntStubs *tclIntStubsPtr;
 #define TclResetCancellation \
 	(tclIntStubsPtr->tclResetCancellation) /* 237 */
 #endif
-#ifndef TclEvalObjv_NR2
-#define TclEvalObjv_NR2 \
-	(tclIntStubsPtr->tclEvalObjv_NR2) /* 238 */
-#endif
 #ifndef TclNRInterpProc
 #define TclNRInterpProc \
-	(tclIntStubsPtr->tclNRInterpProc) /* 239 */
+	(tclIntStubsPtr->tclNRInterpProc) /* 238 */
 #endif
 #ifndef TclNRInterpProcCore
 #define TclNRInterpProcCore \
-	(tclIntStubsPtr->tclNRInterpProcCore) /* 240 */
+	(tclIntStubsPtr->tclNRInterpProcCore) /* 239 */
 #endif
-#ifndef TclNRPushRecord
-#define TclNRPushRecord \
-	(tclIntStubsPtr->tclNRPushRecord) /* 241 */
-#endif
-#ifndef TclNRPopAndFreeRecord
-#define TclNRPopAndFreeRecord \
-	(tclIntStubsPtr->tclNRPopAndFreeRecord) /* 242 */
+#ifndef TclNRRunCallbacks
+#define TclNRRunCallbacks \
+	(tclIntStubsPtr->tclNRRunCallbacks) /* 240 */
 #endif
 #ifndef TclNREvalObjEx
 #define TclNREvalObjEx \
-	(tclIntStubsPtr->tclNREvalObjEx) /* 243 */
+	(tclIntStubsPtr->tclNREvalObjEx) /* 241 */
+#endif
+#ifndef TclNREvalObjv
+#define TclNREvalObjv \
+	(tclIntStubsPtr->tclNREvalObjv) /* 242 */
 #endif
 
 #endif /* defined(USE_TCL_STUBS) && !defined(USE_TCL_STUB_PROCS) */
diff --git a/generic/tclInterp.c b/generic/tclInterp.c
index 025109d..d5736c3 100644
--- a/generic/tclInterp.c
+++ b/generic/tclInterp.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclInterp.c,v 1.93 2008/07/24 22:57:56 nijtmans Exp $
+ * RCS: @(#) $Id: tclInterp.c,v 1.94 2008/07/29 05:30:35 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -687,7 +687,7 @@ Tcl_InterpObjCmd(
 
 	/*
 	 * Did they specify a slave interp to cancel the script in
-	 * progress in?  If not, use the current interp.
+	 * progress in?  If not, use the current interp. 
 	 */
 
 	if (i < objc) {
@@ -1488,7 +1488,7 @@ AliasCreate(
 
     if (slaveInterp == masterInterp) {
 	aliasPtr->slaveCmd = Tcl_NRCreateCommand(slaveInterp,
-		TclGetString(namePtr), AliasObjCmd, AliasNRCmd, aliasPtr,
+		TclGetString(namePtr), AliasObjCmd, AliasNRCmd, aliasPtr, 
 		AliasObjCmdDeleteProc);
     } else {
     aliasPtr->slaveCmd = Tcl_CreateObjCommand(slaveInterp,
@@ -1763,7 +1763,8 @@ AliasNRCmd(
     Tcl_Obj *listPtr;
     List *listRep;
     int flags = TCL_EVAL_INVOKE;
-
+    int result;
+    
     /*
      * Append the arguments to the command prefix and invoke the command in
      * the target interp's global namespace.
@@ -1777,7 +1778,7 @@ AliasNRCmd(
     listRep = listPtr->internalRep.twoPtrValue.ptr1;
     listRep->elemCount = cmdc;
     cmdv = &listRep->elements;
-
+    
     prefv = &aliasPtr->objPtr;
     memcpy(cmdv, prefv, (size_t) (prefc * sizeof(Tcl_Obj *)));
     memcpy(cmdv+prefc, objv+1, (size_t) ((objc-1) * sizeof(Tcl_Obj *)));
@@ -1808,7 +1809,9 @@ AliasNRCmd(
     if (isRootEnsemble) {
 	TclNRAddCallback(interp, TclClearRootEnsemble, NULL, NULL, NULL, NULL);
     }
-    return TclNREvalCmd(interp, listPtr, flags);
+    result = Tcl_NREvalObj(interp, listPtr, flags);
+    TclNRClearCommandFlag(interp);
+    return result;
 }
 
 static int
@@ -2618,7 +2621,7 @@ SlaveEval(
 	 *
 	 * Do not let any intReps accross, with the exception of
 	 * bytecodes. The intrep spoiling is due to happen anyway when
-	 * compiling.
+	 * compiling. 
 	 */
 
         Interp *iPtr = (Interp *) interp;
@@ -2635,7 +2638,7 @@ SlaveEval(
 	}
 
 	TclArgumentGet (interp, objPtr, &invoker, &word);
-
+	
 	result = TclEvalObjEx(slaveInterp, objPtr, 0, invoker, word);
     } else {
 	objPtr = Tcl_ConcatObj(objc, objv);
diff --git a/generic/tclNRE.h b/generic/tclNRE.h
index e0d692d..15f0e54 100644
--- a/generic/tclNRE.h
+++ b/generic/tclNRE.h
@@ -11,7 +11,7 @@
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
  * // FIXME: RCS numbering?
- * RCS: @(#) $Id: tclNRE.h,v 1.6 2008/07/21 16:26:08 msofer Exp $
+ * RCS: @(#) $Id: tclNRE.h,v 1.7 2008/07/29 05:30:36 msofer Exp $
  */
 
 
@@ -23,60 +23,8 @@
  *****************************************************************************/
 
 #define USE_SMALL_ALLOC     1 /* perf is important for some of these things! */
-#define USE_STACK_ALLOC     1 /* good mainly for debugging, crashes at
-			       * smallest timing error */
 #define ENABLE_ASSERTS      1
 
-/*
- *   IMPLEMENTED IN THIS VERSION - flags for partial enabling of the different
- *   parts, useful for debugging. May not work - meant to be used at "all ones"
- */
-
-#define USE_NR_PROC         1 /* are procs defined as NR functions or not?
-			       * Used for testing that the old interfaces
-			       * still work, as they are used by TclOO and
-			       * iTcl */
-#define USE_NR_TEBC         1 /* does TEBC know about his special powers?
-			       * with 1 TEBC remains on stack, TEOV gets
-			       * evicted. */
-#define USE_NR_ALIAS        1 /* First examples: my job */
-
-#define USE_NR_IMPORTS      1 /* First examples: my job */
-
-#define USE_NR_TAILCALLS    1 /* Incomplete implementation as
-			       * tcl::unsupported::tailcall; best semantics
-			       * are yet not 100% clear to me. */
-
-#define USE_NR_NS_ENSEMBLE  1 /* snit!! */
-
-/* Here to remind me of what's still missing: none of these do anything today */
-
-#define USE_NR_EVAL         0 /* Tcl_EvalObj should be easy; the others may
-			       * require some adapting of the parser. dgp? */
-#define USE_NR_UPLEVEL      0 /* piece of cake, I think */
-#define USE_NR_VAR_TRACES   0 /* require major redesign, I fear. About time
-			       * for it too! */
-
-#define USE_NR_CONTINUATIONS 0
-
-#define MAKE_3X_FASTER       0
-#define RULE_THE_WORLD       0
-
-#define USE_NR_CMD_TRACES  /* NEVER?? Maybe ... enter traces on the way in,
-			    * leave traces done in the callback? So a trace
-			    * just needs to replace the procPtr and
-			    * clientData, and TEOV needn't know about the
-			    * whole s**t! Mmhhh */
-
-/*****************************************************************************
- * Stuff for the public api: gone to the stubs table!
- *
- * Question: should we allow more callback requests during the callback
- * itself? Easy enough to either handle or block, nothing done yet. We could
- * also "lock" the Tcl stack during postProc, but it doesn't sound
- * reasonable. I think.
- *****************************************************************************/
-
 /*****************************************************************************
  * Private api fo NRE
  *****************************************************************************/
@@ -94,162 +42,38 @@ typedef struct TEOV_callback {
     struct TEOV_callback *nextPtr;
 } TEOV_callback;
     
-
-/* Try to keep within SmallAlloc sizes! */
-typedef struct TEOV_record {
-    int type;
-    Command *cmdPtr;
-    TEOV_callback *callbackPtr;
-    struct TEOV_record *nextPtr;
-    union {
-	struct ByteCode *codePtr;       /* TCL_NR_BC_TYPE       */
-	struct {
-	    Tcl_Obj *objPtr;
-	    int flags;
-	} obj;
-	struct {
-	    int objc;
-	    Tcl_Obj **objv;
-	} objcv;
-    } data;
-#if !USE_SMALL_ALLOC
-    /* Extra checks: can disappear later */
-    Tcl_Obj **tosPtr;
-#endif
-} TEOV_record;
-
-/*
- * The types for records; we save the first bit to indicate that it stores an
- * obj, to indicate the necessary refCount management. That is, odd numbers
- * only for obj-carrying types
- */
-
-#define TCL_NR_NO_TYPE             0  /* for internal (cleanup) use only */
-#define TCL_NR_BC_TYPE             2  /* procs, lambdas, TclOO+Itcl sometime ... */ 
-#define TCL_NR_CMDSWAP_TYPE        4  /* ns-imports (cmdd redirect) */
-#define TCL_NR_TAILCALL_TYPE       6  
-#define TCL_NR_TEBC_SWAPENV_TYPE   8  /* continuations, micro-threads !? */
-
-#define TCL_NR_CMD_TYPE            1  /* i-alias, ns-ens use this */
-#define TCL_NR_SCRIPT_TYPE         3  /* ns-eval, uplevel use this */
-
-#define TCL_NR_HAS_OBJ(TYPE) ((TYPE) & 1)
-
-#define TOP_RECORD(iPtr) (((Interp *)(iPtr))->execEnvPtr->recordPtr)
+#define TOP_CB(iPtr) (((Interp *)(iPtr))->execEnvPtr->callbackPtr)
 
 #define GET_TOSPTR(iPtr)			\
     (((Interp *)iPtr)->execEnvPtr->execStackPtr->tosPtr)
 
-#if !USE_SMALL_ALLOC
-#define STORE_EXTRA(iPtr, recordPtr)		\
-    recordPtr->tosPtr = GET_TOSPTR(iPtr)
-#else
-#define STORE_EXTRA(iPtr, recordPtr)
-#endif
-
-/* A SINGLE record being pushed is what is detected as an NRE request by TEOV */ 
-
-#define PUSH_RECORD(iPtr, recordPtr)				\
-    TCLNR_ALLOC(interp, recordPtr);	\
-    recordPtr->nextPtr = TOP_RECORD(iPtr);			\
-    STORE_EXTRA(iPtr, recordPtr);				\
-    TOP_RECORD(iPtr) = recordPtr;				\
-    recordPtr->type = TCL_NR_NO_TYPE;                             \
-    recordPtr->cmdPtr = NULL;            			\
-    recordPtr->callbackPtr = NULL
-
-#define TEBC_CALL(iPtr)				\
-    (((Interp *)iPtr)->execEnvPtr->tebcCall)
+/*
+ * Inline version of Tcl_NRAddCallback
+ */
 
-#define TclNRAddCallback(\
-    interp,\
-    postProcPtr,\
-    data0,\
-    data1,\
-    data2,\
-    data3)					\
-    {						\
-	TEOV_record *recordPtr;			\
-	TEOV_callback *callbackPtr;		\
-						\
-	recordPtr = TOP_RECORD(interp);					\
+#define TclNRAddCallback(						\
+    interp,								\
+    postProcPtr,							\
+    data0,								\
+    data1,								\
+    data2,								\
+    data3)								\
+    {									\
+	TEOV_callback *callbackPtr;					\
 	TclSmallAlloc(sizeof(TEOV_callback), callbackPtr);		\
-									\
 	callbackPtr->procPtr = (postProcPtr);				\
 	callbackPtr->data[0] = (data0);					\
 	callbackPtr->data[1] = (data1);					\
 	callbackPtr->data[2] = (data2);					\
 	callbackPtr->data[3] = (data3);					\
-									\
-	callbackPtr->nextPtr = recordPtr->callbackPtr;			\
-	recordPtr->callbackPtr = callbackPtr;				\
+	callbackPtr->nextPtr = TOP_CB(interp);				\
+	TOP_CB(interp) = callbackPtr;					\
     }
-	
-
-
-/*
- * These are only used by TEOV; here for ease of ref. They should move to
- * tclBasic.c later on.
- */
-
-#define COMPLETE_RECORD(recordPtr)			\
-    /* accesses variables by name, careful */		\
-    recordPtr->cmdPtr = cmdPtr;				\
-
-#if !USE_SMALL_ALLOC
-#define CHECK_EXTRA(iPtr, recordPtr)		\
-    (recordPtr->tosPtr == GET_TOSPTR(iPtr))
-#else
-#define CHECK_EXTRA(iPtr, recordPtr) 1
-#endif
-
-#define POP_RECORD(iPtr, recordPtr)		\
-    {						\
-	recordPtr = TOP_RECORD(iPtr);		\
-	TOP_RECORD(iPtr) = recordPtr->nextPtr;	\
-    }
-				 
-
-#define FREE_RECORD(iPtr, recordPtr)					\
-    {									\
-	TEOV_callback *callbackPtr = recordPtr->callbackPtr;		\
-	if (TCL_NR_HAS_OBJ(recordPtr->type)) {		\
-	    Tcl_DecrRefCount(recordPtr->data.obj.objPtr);		\
-	}								\
-	while (callbackPtr) {						\
-	    callbackPtr = callbackPtr->nextPtr;				\
-	    TclSmallFree(recordPtr->callbackPtr);			\
-	}								\
-	TCLNR_FREE(((Tcl_Interp *)iPtr), recordPtr);			\
-    }
-
-#define CHECK_VALID_RETURN(iPtr, recordPtr)			\
-    ((TOP_RECORD(iPtr) == recordPtr)  &&			\
-	    CHECK_EXTRA(iPtr, recordPtr))
-
-#define READ_OBJV_RECORD(recordPtr)   /* TBD? Or read by hand (braille?) */
-
-
-/*
- * functions
- */
-
-#if 0
-/* built as static inline in tclProc.c. Do TclOO/Itcl need this? */
-MODULE_SCOPE int Tcl_NRBC  (Tcl_Interp * interp, ByteCode *codePtr,
-                           Tcl_NRPostProc *postProcPtr, ClientData clientData);
-#endif
-
-/* The following starts purges the stack popping TclStackAllocs down to where
- * tosPtr has the requested value. Panics on failure.*/
-MODULE_SCOPE void TclStackPurge(Tcl_Interp *interp, Tcl_Obj **tosPtr);
 
 /*
  * Tailcalls!
  */
 
-MODULE_SCOPE Tcl_ObjCmdProc TclNRApplyObjCmd;
-MODULE_SCOPE Tcl_ObjCmdProc TclNRUplevelObjCmd;
 MODULE_SCOPE Tcl_ObjCmdProc TclTailcallObjCmd;
 
 
@@ -258,13 +82,10 @@ MODULE_SCOPE Tcl_ObjCmdProc TclTailcallObjCmd;
  *****************************************************************************/
 
 #if USE_SMALL_ALLOC
-#define TCLNR_ALLOC(interp, ptr) TclSmallAlloc(sizeof(TEOV_record), ptr)
+#define TCLNR_ALLOC(interp, ptr) TclSmallAlloc(sizeof(TEOV_callback), ptr)
 #define TCLNR_FREE(interp, ptr)  TclSmallFree((ptr))
-#elif USE_STACK_ALLOC
-#define TCLNR_ALLOC(interp, ptr) (ptr = TclStackAlloc(interp, sizeof(TEOV_record)))
-#define TCLNR_FREE(interp, ptr)  TclStackFree(interp, (ptr))
 #else
-#define TCLNR_ALLOC(interp, size, ptr) (ptr = ((ClientData) ckalloc(sizeof(TEOV_record))))
+#define TCLNR_ALLOC(interp, size, ptr) (ptr = ((ClientData) ckalloc(sizeof(TEOV_callback))))
 #define TCLNR_FREE(interp, ptr)  ckfree((char *) (ptr))
 #endif
 
diff --git a/generic/tclNamesp.c b/generic/tclNamesp.c
index 3eda959..ff56db7 100644
--- a/generic/tclNamesp.c
+++ b/generic/tclNamesp.c
@@ -23,7 +23,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclNamesp.c,v 1.171 2008/07/21 22:50:36 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclNamesp.c,v 1.172 2008/07/29 05:30:36 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -1897,7 +1897,7 @@ InvokeImportedNRCmd(
     ImportedCmdData *dataPtr = clientData;
     Command *realCmdPtr = dataPtr->realCmdPtr;
 
-    return Tcl_NRCmdSwap(interp, (Tcl_Command) realCmdPtr, objc, objv);
+    return Tcl_NRCmdSwap(interp, (Tcl_Command) realCmdPtr, objc, objv, 0);
 }
 
 static int
@@ -6225,7 +6225,7 @@ NsEnsembleImplementationCmdNR(
 				 * target command prefix. */
 	Tcl_Obj *copyPtr;	/* The actual list of words to dispatch to.
 				 * Will be freed by the dispatch engine. */
-	int prefixObjc, copyObjc;
+	int prefixObjc, copyObjc, result;
 	Interp *iPtr = (Interp *) interp;
 
 	/*
@@ -6285,8 +6285,10 @@ NsEnsembleImplementationCmdNR(
 	/*
 	 * Hand off to the target command.
 	 */
-
-	return TclNREvalCmd(interp, copyPtr, TCL_EVAL_INVOKE);
+	
+	result = Tcl_NREvalObj(interp, copyPtr, TCL_EVAL_INVOKE);
+	TclNRClearCommandFlag(interp);
+	return result;
     }
 
   unknownOrAmbiguousSubcommand:
diff --git a/generic/tclOOBasic.c b/generic/tclOOBasic.c
index 2adf547..1e9bd11 100644
--- a/generic/tclOOBasic.c
+++ b/generic/tclOOBasic.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclOOBasic.c,v 1.7 2008/07/18 23:29:44 msofer Exp $
+ * RCS: @(#) $Id: tclOOBasic.c,v 1.8 2008/07/29 05:30:37 msofer Exp $
  */
 
 #ifdef HAVE_CONFIG_H
@@ -49,11 +49,8 @@ static inline Tcl_Object *
 AddConstructionFinalizer(
     Tcl_Interp *interp)
 {
-    TEOV_record *recordPtr;
-
     TclNRAddCallback(interp, FinalizeConstruction, NULL, NULL, NULL, NULL);
-    recordPtr = TOP_RECORD(interp);
-    return (Tcl_Object *) &recordPtr->callbackPtr->data[0];
+    return (Tcl_Object *) &(TOP_CB(interp)->data[0]);
 }
 
 static int
diff --git a/generic/tclOOMethod.c b/generic/tclOOMethod.c
index 8ce3c34..9cd2678 100644
--- a/generic/tclOOMethod.c
+++ b/generic/tclOOMethod.c
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclOOMethod.c,v 1.10 2008/07/27 22:28:54 dkf Exp $
+ * RCS: @(#) $Id: tclOOMethod.c,v 1.11 2008/07/29 05:30:37 msofer Exp $
  */
 
 #ifdef HAVE_CONFIG_H
@@ -55,6 +55,8 @@ static Tcl_Obj **	InitEnsembleRewrite(Tcl_Interp *interp, int objc,
 static int		InvokeProcedureMethod(ClientData clientData,
 			    Tcl_Interp *interp, Tcl_ObjectContext context,
 			    int objc, Tcl_Obj *const *objv);
+static int		FinalizeForwardCall(ClientData data[], Tcl_Interp *interp,
+			    int result);
 static int		FinalizePMCall(ClientData data[], Tcl_Interp *interp,
 			    int result);
 static int		PushMethodCallFrame(Tcl_Interp *interp,
@@ -1131,7 +1133,7 @@ InvokeForwardMethod(
     CallContext *contextPtr = (CallContext *) context;
     ForwardMethod *fmPtr = clientData;
     Tcl_Obj **argObjs, **prefixObjs;
-    int numPrefixes, result, len, skip = contextPtr->skip;
+    int numPrefixes, len, skip = contextPtr->skip;
 
     /*
      * Build the real list of arguments to use. Note that we know that the
@@ -1144,7 +1146,18 @@ InvokeForwardMethod(
     argObjs = InitEnsembleRewrite(interp, objc, objv, skip,
 	    numPrefixes, prefixObjs, &len);
 
-    result = Tcl_NREvalObjv(interp, len, argObjs, TCL_EVAL_INVOKE);
+    Tcl_NRAddCallback(interp, FinalizeForwardCall, argObjs, NULL, NULL, NULL);
+    return Tcl_NREvalObjv(interp, len, argObjs, TCL_EVAL_INVOKE);
+}
+
+static int
+FinalizeForwardCall(
+    ClientData data[],
+    Tcl_Interp *interp,
+    int result)
+{
+    Tcl_Obj **argObjs = data[0];
+    
     TclStackFree(interp, argObjs);
     return result;
 }
diff --git a/generic/tclProc.c b/generic/tclProc.c
index 63aa7d5..ea5f617 100644
--- a/generic/tclProc.c
+++ b/generic/tclProc.c
@@ -12,7 +12,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclProc.c,v 1.152 2008/07/25 22:11:21 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclProc.c,v 1.153 2008/07/29 05:30:37 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -1618,23 +1618,6 @@ PushProcCallFrame(
     return TCL_OK;
 }
 
-static int
-Tcl_NRBC(
-    Tcl_Interp *interp,
-    ByteCode *codePtr,
-    Tcl_NRPostProc *postProcPtr,
-    Tcl_Obj *procNameObj,
-    ProcErrorProc errorProc)
-{
-    TEOV_record *recordPtr = TOP_RECORD(interp);
-
-    recordPtr->type = TCL_NR_BC_TYPE;
-    recordPtr->data.codePtr = codePtr;
-    TclNRAddCallback(interp, postProcPtr, procNameObj, errorProc, NULL,
-	    NULL);
-    return TCL_OK;
-}
-
 /*
  *----------------------------------------------------------------------
  *
@@ -1663,16 +1646,10 @@ TclObjInterpProc(
     Tcl_Obj *const objv[])	/* Argument value objects. */
 {
     /*
-     * Not used in the core; external interface for iTcl and XOTcl
+     * Not used much in the core; external interface for iTcl
      */
     
-    int result = PushProcCallFrame(clientData, interp, objc, objv,
-	    /*isLambda*/ 0);
-
-    if (result != TCL_OK) {
-	return TCL_ERROR;
-    }
-    return TclObjInterpProcCore(interp, objv[0], 1, &MakeProcError);
+    return Tcl_NRCallObjProc(interp, TclNRInterpProc, clientData, objc, objv);
 }
 
 int
@@ -1697,7 +1674,7 @@ TclNRInterpProc(
 /*
  *----------------------------------------------------------------------
  *
- * TclObjInterpProcCore --
+ * TclNRInterpProcCore --
  *
  *	When a Tcl procedure, lambda term or anything else that works like a
  *	procedure gets invoked during bytecode evaluation, this object-based
@@ -1713,49 +1690,6 @@ TclNRInterpProc(
  */
 
 int
-TclObjInterpProcCore(
-    register Tcl_Interp *interp,/* Interpreter in which procedure was
-				 * invoked. */
-    Tcl_Obj *procNameObj,	/* Procedure name for error reporting. */
-    int skip,			/* Number of initial arguments to be skipped,
-				 * i.e., words in the "command name". */
-    ProcErrorProc errorProc)	/* How to convert results from the script into
-				 * results of the overall procedure. */
-{
-    /*
-     * Not used in the core; external interface for TclOO
-     */
-    
-    Interp *iPtr = (Interp *) interp;
-    TEOV_record record, *rootPtr;
-    int result;
-    
-    /*
-     * Put a top record NOT ON THE TCL STACK! Note that TclNRInterpProcCore
-     * assumes it can free the CallFrame in the error case, there cannot be
-     * anything else on top of that. We use a C-stack record, it could also be
-     * ckalloc'ed or anything else, just NOT TclStackAlloc.
-     */
-
-    rootPtr = TOP_RECORD(iPtr);
-    TOP_RECORD(iPtr) = &record;
-    result = TclNRInterpProcCore(interp, procNameObj, skip, errorProc);
-    TOP_RECORD(iPtr) = rootPtr;
-
-    if (result == TCL_OK) {
-    	result = TclExecuteByteCode(interp, record.data.codePtr);
-	result = TclEvalObjv_NR2(interp, result, rootPtr);
-	if (TOP_RECORD(iPtr) != rootPtr) {
-	    /* FIXME NRE & tailcalls */
-	    Tcl_Panic("TclObjInterpProcCore not yet prepared to deal with evals in callbacks!");
-	}
-	result = InterpProcNR2(record.callbackPtr->data, interp, result);
-	TclSmallFree(record.callbackPtr);
-    }
-    return result;
-}
-
-int
 TclNRInterpProcCore(
     register Tcl_Interp *interp,/* Interpreter in which procedure was
 				 * invoked. */
@@ -1837,7 +1771,9 @@ TclNRInterpProcCore(
 		(Tcl_Obj **)(iPtr->varFramePtr->objv + l));
     }
 
-    Tcl_NRBC(interp, codePtr, InterpProcNR2, procNameObj, errorProc);
+    TclNRAddCallback(interp, InterpProcNR2, procNameObj, errorProc,
+	    NULL, NULL);
+    TclNRAddCallback(interp, NRRunBytecode, codePtr, NULL, NULL, NULL);
     return TCL_OK;
 }
 
@@ -2825,21 +2761,8 @@ TclNRApplyObjCmd(
 
     result = PushProcCallFrame((ClientData) procPtr, interp, objc, objv, 1);
     if (result == TCL_OK) {
+	TclNRAddCallback(interp, ApplyNR2, extraPtr, NULL, NULL, NULL);
 	result = TclNRInterpProcCore(interp, objv[1], 2, &MakeLambdaError);
-	if (result == TCL_OK) {
-	    /* Fix the recordPtr! */
-
-	    TEOV_record *recordPtr = TOP_RECORD(iPtr);
-
-	    recordPtr->callbackPtr->procPtr = ApplyNR2;
-	    recordPtr->callbackPtr->data[2] = extraPtr;
-	}
-    }
-    if (result != TCL_OK) {
-	if (isRootEnsemble) {
-	    iPtr->ensembleRewrite.sourceObjs = NULL;
-	}
-	TclStackFree(interp, extraPtr);
     }
     return result;
 }
@@ -2850,10 +2773,8 @@ ApplyNR2(
     Tcl_Interp *interp,
     int result)
 {
-    ApplyExtraData *extraPtr = data[2];
+    ApplyExtraData *extraPtr = data[0];
     
-    result = InterpProcNR2(data, interp, result);
-
     if (extraPtr->isRootEnsemble) {
 	((Interp *) interp)->ensembleRewrite.sourceObjs = NULL;
     }
diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index 76c0e15..49f5029 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclStubInit.c,v 1.161 2008/07/22 23:06:25 das Exp $
+ * RCS: @(#) $Id: tclStubInit.c,v 1.162 2008/07/29 05:30:38 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -297,7 +297,7 @@ static const TclIntStubs tclIntStubs = {
     TclTraceDictPath, /* 225 */
     TclObjBeingDeleted, /* 226 */
     TclSetNsPath, /* 227 */
-    TclObjInterpProcCore, /* 228 */
+    NULL, /* 228 */
     TclPtrMakeUpvar, /* 229 */
     TclObjLookupVar, /* 230 */
     TclGetNamespaceFromObj, /* 231 */
@@ -307,12 +307,11 @@ static const TclIntStubs tclIntStubs = {
     TclInitVarHashTable, /* 235 */
     TclBackgroundException, /* 236 */
     TclResetCancellation, /* 237 */
-    TclEvalObjv_NR2, /* 238 */
-    TclNRInterpProc, /* 239 */
-    TclNRInterpProcCore, /* 240 */
-    TclNRPushRecord, /* 241 */
-    TclNRPopAndFreeRecord, /* 242 */
-    TclNREvalObjEx, /* 243 */
+    TclNRInterpProc, /* 238 */
+    TclNRInterpProcCore, /* 239 */
+    TclNRRunCallbacks, /* 240 */
+    TclNREvalObjEx, /* 241 */
+    TclNREvalObjv, /* 242 */
 };
 
 static const TclIntPlatStubs tclIntPlatStubs = {
@@ -1108,13 +1107,13 @@ static const TclStubs tclStubs = {
     Tcl_AppendPrintfToObj, /* 579 */
     Tcl_CancelEval, /* 580 */
     Tcl_Canceled, /* 581 */
-    Tcl_NRCreateCommand, /* 582 */
-    Tcl_NREvalObj, /* 583 */
-    Tcl_NREvalObjv, /* 584 */
-    Tcl_NRCmdSwap, /* 585 */
-    Tcl_NRAddCallback, /* 586 */
-    Tcl_NRCallObjProc, /* 587 */
-    Tcl_CreatePipe, /* 588 */
+    Tcl_CreatePipe, /* 582 */
+    Tcl_NRCreateCommand, /* 583 */
+    Tcl_NREvalObj, /* 584 */
+    Tcl_NREvalObjv, /* 585 */
+    Tcl_NRCmdSwap, /* 586 */
+    Tcl_NRAddCallback, /* 587 */
+    Tcl_NRCallObjProc, /* 588 */
 };
 
 /* !END!: Do not edit above this line. */
diff --git a/generic/tclTest.c b/generic/tclTest.c
index 3052cc9..4ce4277 100644
--- a/generic/tclTest.c
+++ b/generic/tclTest.c
@@ -14,7 +14,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclTest.c,v 1.118 2008/07/28 21:31:19 nijtmans Exp $
+ * RCS: @(#) $Id: tclTest.c,v 1.119 2008/07/29 05:30:38 msofer Exp $
  */
 
 #define TCL_TEST
@@ -402,6 +402,9 @@ static int		TestNumUtfCharsCmd(ClientData clientData,
 static int		TestHashSystemHashCmd(ClientData clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
+static int		TestNRELevels(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const objv[]);
 
 static const Tcl_Filesystem testReportingFilesystem = {
     "reporting",
@@ -658,6 +661,10 @@ Tcltest_Init(
     Tcl_CreateMathFunc(interp, "T3", 2, t3ArgTypes, TestMathFunc2,
 	    (ClientData) 0);
 
+    Tcl_CreateObjCommand(interp, "testnrelevels", TestNRELevels,
+	    (ClientData) NULL, NULL);
+
+
 #ifdef TCL_THREADS
     if (TclThread_Init(interp) != TCL_OK) {
 	return TCL_ERROR;
@@ -6527,6 +6534,35 @@ TestgetintCmd(
     }
 }
 
+static int
+TestNRELevels(
+    ClientData clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    Interp *iPtr = (Interp *) interp;
+    static ptrdiff_t *refDepth = NULL;
+    ptrdiff_t depth;
+    Tcl_Obj *levels[5];
+
+    if (refDepth == NULL) {
+	refDepth = &depth;
+    }
+	
+    depth = (refDepth - &depth);
+
+    levels[0] = Tcl_NewIntObj(depth);
+    levels[1] = Tcl_NewIntObj(((Interp *)interp)->numLevels);
+    levels[2] = Tcl_NewIntObj(iPtr->cmdFramePtr->level);
+    levels[3] = Tcl_NewIntObj(iPtr->varFramePtr->level);
+    levels[4] = Tcl_NewIntObj((iPtr->execEnvPtr->execStackPtr->tosPtr
+		    - iPtr->execEnvPtr->execStackPtr->stackWords));
+    
+    Tcl_SetObjResult(interp, Tcl_NewListObj(5, levels));
+    return TCL_OK;
+}
+
 /*
  * Local Variables:
  * mode: c