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| author | Miguel Sofer <miguel.sofer@gmail.com> | 2004-09-10 15:30:01 (GMT) |
|---|---|---|
| committer | Miguel Sofer <miguel.sofer@gmail.com> | 2004-09-10 15:30:01 (GMT) |
| commit | b94a66126401085879ed9e146d694bda9416a37d (patch) | |
| tree | 269aa3736a882e762fde8fc0e6cd871aafbc041b | |
| parent | 045fc77ff4e4fe4a8733883a90adc96d68fc6547 (diff) | |
| download | tcl-b94a66126401085879ed9e146d694bda9416a37d.zip tcl-b94a66126401085879ed9e146d694bda9416a37d.tar.gz tcl-b94a66126401085879ed9e146d694bda9416a37d.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 Don Porter <dgp@users.sourceforge.net> * generic/tclNamesp.c (Tcl_ForgetImport): Corrected faulty diff --git a/generic/tclExecute.c b/generic/tclExecute.c index 79b03b9..b0a94fe 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 1.94.2.7 2004/07/03 22:13:10 msofer Exp $ + * RCS: @(#) $Id: tclExecute.c,v 1.94.2.8 2004/09/10 15:30:02 msofer Exp $ */ #include "tclInt.h" @@ -1264,6 +1264,20 @@ TclExecuteByteCode(interp, codePtr) int totalLen = 0; /* + * 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(stackPtr[stackTop], &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. |