From 11915ee6b5791aab49447d524ef382336aeec38d Mon Sep 17 00:00:00 2001
From: Miguel Sofer <miguel.sofer@gmail.com>
Date: Fri, 11 Dec 2009 04:47:13 +0000
Subject: simplify the coroutine BP-chain monkey-patching; tclBasic does not
 need to know about bottomPtr, tebc does not need to behave differently on
 exit for coros

---
 generic/tclBasic.c   |  4 +---
 generic/tclExecute.c | 43 ++++++++++++++-----------------------------
 generic/tclInt.h     |  9 +++++----
 3 files changed, 20 insertions(+), 36 deletions(-)

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index d8a449b..79d76be 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 1.429 2009/12/10 23:52:30 msofer Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.430 2009/12/11 04:47:13 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -8717,7 +8717,6 @@ NRInterpCoroutine(
     TclNRAddCallback(interp, NRCoroutineCallerCallback, corPtr, NULL, NULL,
 	    NULL);
 
-    corPtr->callerBP = NULL;;
     corPtr->callerEEPtr = iPtr->execEnvPtr;
     iPtr->execEnvPtr = corPtr->eePtr;
 
@@ -8852,7 +8851,6 @@ TclNRCoroutineObjCmd(
     corPtr->running = NULL_CONTEXT;
     corPtr->stackLevel = NULL;
     corPtr->auxNumLevels = iPtr->numLevels;
-    corPtr->callerBP = NULL;
     
     /*
      * Create the command that will run at the bottom of the coroutine.
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index f4a204e..fdc2dc4 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 1.462 2009/12/10 23:52:30 msofer Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.463 2009/12/11 04:47:13 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -1972,21 +1972,27 @@ TclExecuteByteCode(
      * execution stack is large enough to execute this ByteCode.
      */
 
-    resumeCoroutine:
     if (!codePtr) {
-	CoroutineData *corPtr = iPtr->execEnvPtr->corPtr;
+	CoroutineData *corPtr;
+
+    resumeCoroutine:
 	/*
 	 * Reawakening a suspended coroutine: the [yield] command is
 	 * returning.
 	 */
 
+	corPtr = iPtr->execEnvPtr->corPtr;
+
 	NRE_ASSERT(corPtr != NULL);
 	NRE_ASSERT(corPtr->eePtr == iPtr->execEnvPtr);
 	NRE_ASSERT(COR_IS_SUSPENDED(corPtr));
 
+	*corPtr->callerBPPtr = OBP;
 	OBP = iPtr->execEnvPtr->bottomPtr;
+	
 	corPtr->stackLevel = &TAUX;
 	corPtr->base.cmdFramePtr->nextPtr = corPtr->caller.cmdFramePtr;
+	
 	if (iPtr->execEnvPtr->rewind) {
 	    TRESULT = TCL_ERROR;
 	}
@@ -2040,8 +2046,7 @@ TclExecuteByteCode(
 	    
 	    corPtr->base.cmdFramePtr = bcFramePtr;
 	    iPtr->varFramePtr = iPtr->rootFramePtr;
-	    corPtr->callerBP = BP->prevBottomPtr;
-	    BP->prevBottomPtr = NULL;
+	    corPtr->callerBPPtr = &BP->prevBottomPtr;
 	}
 	
 	if (!corPtr->stackLevel) {
@@ -2833,13 +2838,11 @@ TclExecuteByteCode(
 			 * new one.
 			 */
 
-			codePtr = param;
-			if (codePtr) {
+			if (param) {
+			    codePtr = param;
 			    goto nonRecursiveCallStart;
 			} else {
-			    CoroutineData *corPtr = iPtr->execEnvPtr->corPtr;
-
-			    corPtr->callerBP = BP;
+			    OBP = BP;
 			    goto resumeCoroutine;
 			}
 			break;
@@ -2900,7 +2903,7 @@ TclExecuteByteCode(
 			    
 			corPtr->stackLevel = NULL;			
 			iPtr->execEnvPtr = corPtr->callerEEPtr;
-			OBP = corPtr->callerBP;
+			OBP = *corPtr->callerBPPtr;
 			goto returnToCaller;
 		    }
 		    default:
@@ -8027,24 +8030,6 @@ TclExecuteByteCode(
 	}
     }
 
-    /*
-     * Deal with coros running in the caller's TEBC
-     */
-    
-    if (iPtr->execEnvPtr->corPtr) {
-	CoroutineData *corPtr = iPtr->execEnvPtr->corPtr;
-	/*
-	 * The coro is returning internally iff
-	 *    - this is its base TEBC
-	 *    - this is it's callers TEBC, signalled by callerBP!=NULL 
-	 */
-	
-	OBP = corPtr->callerBP;
-	if (OBP && (corPtr->stackLevel == &TAUX)) {
-	    goto returnToCaller;
-	}
-    }
-
     iPtr->execEnvPtr->bottomPtr = NULL;
     return TRESULT;
 }
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 91f301f..bf13446 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -15,7 +15,7 @@
  * 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 1.452 2009/12/08 20:56:29 msofer Exp $
+ * RCS: @(#) $Id: tclInt.h,v 1.453 2009/12/11 04:47:13 msofer Exp $
  */
 
 #ifndef _TCLINT
@@ -1405,9 +1405,10 @@ typedef struct CoroutineData {
 				 * numLevels of the create/resume command is
 				 * stored here; for suspended coroutines it
 				 * holds the nesting numLevels at yield. */
-    struct BottomData *callerBP;/* The caller's bottomPointer, if the coro is
-				 * running in the caller's TEBC instance. NULL
-				 * otherwise. */
+    struct BottomData **callerBPPtr;
+                                /* Where to stash the caller's bottomPointer,
+				 * if the coro is running in the caller's TEBC 
+				 * instance. Put a NULL in there otherwise. */
 } CoroutineData;
 
 typedef struct ExecEnv {
-- 
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