Improved the sequence of instructions issued for [subst] when dealing with

simple variable references.

2 files changed, 39 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 13fcaf8..6104af0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,14 +1,19 @@
+2012-12-18  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tclCompCmdsSZ.c (TclSubstCompile): Improved the sequence of
+	instructions issued for [subst] when dealing with simple variable
+	references.
+
 2012-11-13  Miguel Sofer  <msofer@users.sf.net>
 
-	* generic/tclCmdAH.c (CatchObjCmdCallback): do not decrRefCount
-	the newValuePtr sent to Tcl_ObjSetVar2: TOSV2 is 'fire and
-	forget', it decrs on its own. Fix for [Bug 3595576], found by
-	andrewsh.
+	* generic/tclCmdAH.c (CatchObjCmdCallback): Do not decrRefCount the
+	newValuePtr sent to Tcl_ObjSetVar2: TOSV2 is 'fire and forget', it
+	decrs on its own. Fix for [Bug 3595576], found by andrewsh.
 
 2012-12-13  Jan Nijtmans  <nijtmans@users.sf.net>
 
-	* generic/tcl.h: Fix Tcl_DecrRefCount macro such that it
-	doesn't access its objPtr parameter twice any more.
+	* generic/tcl.h: Fix Tcl_DecrRefCount macro such that it doesn't
+	access its objPtr parameter twice any more.
 
 2012-12-10  Donal K. Fellows  <dkf@users.sf.net>
 
diff --git a/generic/tclCompCmdsSZ.c b/generic/tclCompCmdsSZ.c
index 9c93fb2..7bead0d 100644
--- a/generic/tclCompCmdsSZ.c
+++ b/generic/tclCompCmdsSZ.c
@@ -836,6 +836,34 @@ TclSubstCompile(
 	    TclEmitPush(literal, envPtr);
 	    count++;
 	    continue;
+	case TCL_TOKEN_VARIABLE:
+	    /*
+	     * Check for simple variable access; see if we can only generate
+	     * TCL_OK or TCL_ERROR from the substituted variable read; if so,
+	     * there is no need to generate elaborate exception-management
+	     * code. Note that the first component of TCL_TOKEN_VARIABLE is
+	     * always TCL_TOKEN_TEXT...
+	     */
+
+	    if (tokenPtr->numComponents > 1) {
+		int i, foundCommand = 0;
+
+		for (i=2 ; i<=tokenPtr->numComponents ; i++) {
+		    if (tokenPtr[i].type == TCL_TOKEN_COMMAND) {
+			foundCommand = 1;
+			break;
+		    }
+		}
+		if (foundCommand) {
+		    break;
+		}
+	    }
+
+	    envPtr->line = bline;
+	    TclCompileVarSubst(interp, tokenPtr, envPtr);
+	    bline = envPtr->line;
+	    count++;
+	    continue;
 	}
 
 	while (count > 255) {