Date: Fri, 5 Apr 2002 13:10:33 +0200 From: Bernd Walter <ticso@cicely8.cicely.de> To: Mikhail Teterin <mi@aldan.algebra.com> Cc: obrien@FreeBSD.org, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/usr.bin/yacc main.c Message-ID: <20020405111032.GM51284@cicely8.cicely.de> In-Reply-To: <200204042243.g34MhonF007316@aldan.algebra.com> References: <200204042215.g34MFDb67996@freefall.freebsd.org> <200204042243.g34MhonF007316@aldan.algebra.com>
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On Thu, Apr 04, 2002 at 05:43:50PM -0500, Mikhail Teterin wrote:
> On 4 Apr, David E. O'Brien wrote:
> > obrien 2002/04/04 14:15:13 PST
> >
> > Modified files:
> > usr.bin/yacc main.c
> > Log:
> [...]
> > Use strlen() rather than magic number.
> [...]
>
> Beware of strlen :) The magic number was just a ``sizeof temp_form'' --
> computed at the code-writing time. Your change moved the computation to
> run-time, which, IMHO, is too far. How about the following patch, which
> will move it to the compile-time (untested):
It's main - a *one time* code path.
I'm all for adding performance, but rarely used code should favour
for readability and size.
Your suggestion is more complex and bigger.
And finaly gcc with -O *knows* that strlen("some string") results
in a constant value.
>
> Index: main.c
> ===================================================================
> RCS file: /home/ncvs/src/usr.bin/yacc/main.c,v
> retrieving revision 1.19
> diff -U2 -r1.19 main.c
> --- main.c 4 Apr 2002 22:15:56 -0000 1.19
> +++ main.c 4 Apr 2002 22:41:35 -0000
> @@ -302,9 +302,11 @@
> const char *tmpdir;
>
> - if (!(tmpdir = getenv("TMPDIR")))
> + if (!(tmpdir = getenv("TMPDIR"))) {
> tmpdir = _PATH_TMP;
> + len = sizeof _PATH_TMP - 1;
> + } else
> + len = strlen(tmpdir);
>
> - len = strlen(tmpdir);
> - i = len + strlen(temp_form) + 1;
> + i = len + sizeof temp_form;
> if (len && tmpdir[len-1] != '/')
> ++i;
--
B.Walter COSMO-Project http://www.cosmo-project.de
ticso@cicely.de Usergroup info@cosmo-project.de
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