* generic/tclCompCmds.c (TclCompileCatchCmd): Added a more efficient

	bytecode generator for the case where 'catch' is used without any
	variable arguments; don't capture the result just to discard it.

2 files changed, 40 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index e43d7ac..9da588f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,10 +1,16 @@
+2012-01-30  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tclCompCmds.c (TclCompileCatchCmd): Added a more efficient
+	bytecode generator for the case where 'catch' is used without any
+	variable arguments; don't capture the result just to discard it.
+
 2012-01-26  Don Porter  <dgp@users.sourceforge.net>
 
-	* generic/tclCmdAH.c:		New internal routine TclJoinPath().
-	* generic/tclFCmd.c:		Refactor all the *Join*Path* routines
-	* generic/tclFileName.c:	to give them more useful interfaces
-	* generic/tclInt.h:		that are easier to manage getting the
-	* generic/tclPathObj.c:		refcounts right. [Bug 3479689]
+	* generic/tclCmdAH.c:		[Bug 3479689]: New internal routine
+	* generic/tclFCmd.c:		TclJoinPath(). Refactor all the
+	* generic/tclFileName.c:	*Join*Path* routines to give them more
+	* generic/tclInt.h:		useful interfaces that are easier to
+	* generic/tclPathObj.c:		manage getting the refcounts right.
 
 2012-01-26  Don Porter  <dgp@users.sourceforge.net>
 
diff --git a/generic/tclCompCmds.c b/generic/tclCompCmds.c
index 69b44ed..1edb56b 100644
--- a/generic/tclCompCmds.c
+++ b/generic/tclCompCmds.c
@@ -390,6 +390,32 @@ TclCompileCatchCmd(
      *    simple:            <mark> result
      */
 
+    if (resultIndex == -1) {
+	/*
+	 * Special case when neither result nor options are being saved. In
+	 * that case, we can skip quite a bit of the command epilogue; all we
+	 * have to do is drop the result and push the return code (and, of
+	 * course, finish the catch context).
+	 */
+
+	TclEmitOpcode(		INST_POP,			envPtr);
+	PushLiteral(envPtr, "0", 1);
+	TclEmitInstInt1(	INST_JUMP1, 3,			envPtr);
+	envPtr->currStackDepth = savedStackDepth;
+	ExceptionRangeTarget(envPtr, range, catchOffset);
+	TclEmitOpcode(		INST_PUSH_RETURN_CODE,		envPtr);
+	ExceptionRangeEnds(envPtr, range);
+	TclEmitOpcode(		INST_END_CATCH,			envPtr);
+
+	/*
+	 * Stack at this point:
+	 *    nonsimple:  script <mark> returnCode
+	 *    simple:            <mark> returnCode
+	 */
+
+	goto dropScriptAtEnd;
+    }
+
     /*
      * Emit the "no errors" epilogue: push "0" (TCL_OK) as the catch
      * result, and jump around the "error case" code.
@@ -467,7 +493,9 @@ TclCompileCatchCmd(
 	TclEmitOpcode(		INST_POP,			envPtr);
     }
 
-    /* 
+  dropScriptAtEnd:
+
+    /*
      * Stack is now ?script? result. Get rid of the subst'ed script
      * if it's hanging arond.
      */