From 7ae4115a5e7d953245963c4287ad342e9c0f54ba Mon Sep 17 00:00:00 2001 From: Miguel Sofer Date: Fri, 10 Sep 2004 12:48:34 +0000 Subject: * 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. --- ChangeLog | 7 +++++++ generic/tclExecute.c | 16 +++++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index f859f54..f0fd156 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2004-09-10 Miguel Sofer + + * 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. + 2004-09-09 David Gravereaux * win/tclWinConsole.c: Calls to WriteFile and WriteConsoleA 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. -- cgit v0.12