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| author | Miguel Sofer <miguel.sofer@gmail.com> | 2004-09-10 12:48:34 (GMT) |
|---|---|---|
| committer | Miguel Sofer <miguel.sofer@gmail.com> | 2004-09-10 12:48:34 (GMT) |
| commit | 7ae4115a5e7d953245963c4287ad342e9c0f54ba (patch) | |
| tree | 2e5183af73491bbe7705551e34535bf3d2aaea95 | |
| parent | 3b09378118bfed68006ac0cb3e3dc2c5abbe04e4 (diff) | |
| download | tcl-7ae4115a5e7d953245963c4287ad342e9c0f54ba.zip tcl-7ae4115a5e7d953245963c4287ad342e9c0f54ba.tar.gz tcl-7ae4115a5e7d953245963c4287ad342e9c0f54ba.tar.bz2 | |
* 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.
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | generic/tclExecute.c | 16 |
2 files changed, 22 insertions, 1 deletions
@@ -1,3 +1,10 @@ +2004-09-10 Miguel Sofer <msofer@users.sf.net> + + * 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 <davygrvy@pobox.com> * 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. |