Re: [TRIVIAL] strlen("literal string") -> (sizeof("literal string")-1)

Rusty Russell
2002-08-29T03:12:34Z

In message <200208282131.g7SLVVGx024191@siamese.dyndns.org> you write:
> Here is a patch that does the same as what Keith Owens did in
> his patch recently.
>
> Message-ID: <fa.iks3ohv.1flge08@ifi.uio.no>
> From: Keith Owens <kaos@ocs.com.au>
> Subject: [patch] 2.4.19 Generate better code for nfs_sillyrename
> Date: Wed, 28 Aug 2002 07:08:17 GMT
>
> Using strlen() generates an unnecessary inline function expansion plus
> dynamic stack adjustment. For constant strings, strlen() == sizeof()-1
> and the object code is better.

Disagree. If you really care make strlen use __builtin_constant_p().
Then authors don't have to sacrifice readability.

#define strlen(x) (__builtin_constant_p(x) ? sizeof(x)-1 : __strlen(x))

Rusty.
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.