better rewritten loop optimization: new evalFlag "TCL_EVAL_DISCARD_RESULT" introduced, which allows to organize faster TEBC-loop

with discarding of result, simulating pop & done, like it does continue in loop (so ensures that setting of result will not smudge
the measurement).

4 files changed, 22 insertions, 16 deletions

diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index b4283d0..d16baa9 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -4328,7 +4328,6 @@ Tcl_TimeRateObjCmd(
     };
     NRE_callback *rootPtr;
     ByteCode *codePtr = NULL;
-    int codeOptimized = 0;
 
     for (i = 1; i < objc - 1; i++) {
 	int index;
@@ -4513,15 +4512,6 @@ Tcl_TimeRateObjCmd(
 	}
 	codePtr = TclCompileObj(interp, objPtr, NULL, 0);
 	TclPreserveByteCode(codePtr);
-	/*
-	 * Replace last compiled done instruction with continue: it's a part of
-	 * iteration, this way evaluation will be more similar to a cycle (also
-	 * avoids extra overhead to set result to interp, etc.)
-	 */
-	if (codePtr->codeStart[codePtr->numCodeBytes-1] == INST_DONE) {
-	    codePtr->codeStart[codePtr->numCodeBytes-1] = INST_CONTINUE;
-	    codeOptimized = 1;
-	}
     }
 
     /*
@@ -4563,8 +4553,10 @@ Tcl_TimeRateObjCmd(
 	    count++;
 	    if (!direct) {		/* precompiled */
 		rootPtr = TOP_CB(interp);
+		((Interp *)interp)->evalFlags |= TCL_EVAL_DISCARD_RESULT;
 		result = TclNRExecuteByteCode(interp, codePtr);
 		result = TclNRRunCallbacks(interp, result, rootPtr);
+		((Interp *)interp)->evalFlags &= ~TCL_EVAL_DISCARD_RESULT;
 	    } else {			/* eval */
 		result = TclEvalObjEx(interp, objPtr, 0, NULL, 0);
 	    }
@@ -4815,11 +4807,6 @@ Tcl_TimeRateObjCmd(
 
   done:
     if (codePtr != NULL) {
-	if ( codeOptimized
-	  && codePtr->codeStart[codePtr->numCodeBytes-1] == INST_CONTINUE
-	) {
-	    codePtr->codeStart[codePtr->numCodeBytes-1] = INST_DONE;
-	}
 	TclReleaseByteCode(codePtr);
     }
     return result;
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index cdf0c5d..6959c00 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -2624,6 +2624,14 @@ TEBCresume(
 
     case INST_DONE:
 	if (tosPtr > initTosPtr) {
+
+	    if ((iPtr->evalFlags & TCL_EVAL_DISCARD_RESULT) && (result == TCL_OK)) {
+		/* simulate pop & fast done (like it does continue in loop) */
+		TRACE_WITH_OBJ(("=> discarding "), OBJ_AT_TOS);
+		objPtr = POP_OBJECT();
+		TclDecrRefCount(objPtr);
+		goto abnormalReturn;
+	    }
 	    /*
 	     * Set the interpreter's object result to point to the topmost
 	     * object from the stack, and check for a possible [catch]. The
@@ -8084,7 +8092,7 @@ TEBCresume(
 	 */
 
 	/*
-	 * Abnormal return code. Restore the stack to state it had when
+	 * Done or abnormal return code. Restore the stack to state it had when
 	 * starting to execute the ByteCode. Panic if the stack is below the
 	 * initial level.
 	 */
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 708f60a..edf7df6 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -2206,6 +2206,7 @@ typedef struct Interp {
 #define TCL_EVAL_FILE			0x02
 #define TCL_EVAL_SOURCE_IN_FRAME	0x10
 #define TCL_EVAL_NORESOLVE		0x20
+#define TCL_EVAL_DISCARD_RESULT		0X40
 
 /*
  * Flag bits for Interp structures:
diff --git a/tests/cmdMZ.test b/tests/cmdMZ.test
index 4286bbb..1157ada 100644
--- a/tests/cmdMZ.test
+++ b/tests/cmdMZ.test
@@ -353,6 +353,11 @@ test cmdMZ-5.7 {Tcl_TimeObjCmd: errors generate right trace} {
 "error foo"
     invoked from within
 "time {error foo}"}}
+test cmdMZ-5.7.1 {Tcl_TimeObjCmd: return from time} {
+    set x 0
+    proc r1 {} {upvar x x; time {incr x; return "r1"; incr x} 10}
+    list [r1] $x
+} {r1 1}
 
 test cmdMZ-6.1 {Tcl_TimeRateObjCmd: basic format of command} {
     list [catch {timerate} msg] $msg
@@ -399,6 +404,11 @@ test cmdMZ-6.7 {Tcl_TimeRateObjCmd: errors generate right trace} {
 "error foo"
     invoked from within
 "timerate {error foo} 1"}}
+test cmdMZ-6.7.1 {Tcl_TimeRateObjCmd: return from timerate} {
+    set x 0
+    proc r1 {} {upvar x x; timerate {incr x; return "r1"; incr x} 1000 10}
+    list [r1] $x
+} {r1 1}
 test cmdMZ-6.8 {Tcl_TimeRateObjCmd: allow (conditional) break from timerate} {
     set m1 [timerate {break}]
     list \