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authorMiguel Sofer <miguel.sofer@gmail.com>2004-09-10 12:48:34 (GMT)
committerMiguel Sofer <miguel.sofer@gmail.com>2004-09-10 12:48:34 (GMT)
commit7ae4115a5e7d953245963c4287ad342e9c0f54ba (patch)
tree2e5183af73491bbe7705551e34535bf3d2aaea95 /generic
parent3b09378118bfed68006ac0cb3e3dc2c5abbe04e4 (diff)
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* generic/tclExecute.c (INST_CONCAT1): added a peephole
optimisation for concatting an empty string. This enables replacing the idiom 'K $x [set x {}]' by '$x[set x {}]' for fastest execution.
Diffstat (limited to 'generic')
-rw-r--r--generic/tclExecute.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index efbea33..39d87a0 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -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: tclExecute.c,v 1.145 2004/07/11 21:56:01 msofer Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.146 2004/09/10 12:48:36 msofer Exp $
*/
#ifdef STDC_HEADERS
@@ -1424,6 +1424,20 @@ TclExecuteByteCode(interp, codePtr)
opnd = TclGetUInt1AtPtr(pc+1);
/*
+ * Peephole optimisation for appending an empty string.
+ * This enables replacing 'K $x [set x{}]' by '$x[set x{}]'
+ * for fastest execution.
+ */
+
+ if (opnd == 2) {
+ Tcl_GetStringFromObj(*tosPtr, &length);
+ if (length == 0) {
+ /* Just drop the top item from the stack */
+ NEXT_INST_F(2, 1, 0);
+ }
+ }
+
+ /*
* Concatenate strings (with no separators) from the top
* opnd items on the stack starting with the deepest item.
* First, determine how many characters are needed.