From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH] fs: Cleanup string initializations (char[] instead of
 char *)
Date: Sat, 17 May 2014 17:53:45 +0100
Message-ID: <20140517165345.GG18016@ZenIV.linux.org.uk>
References: <1400338818-2853-1-git-send-email-manuel.schoelling@gmx.de>
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Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
To: Manuel =?iso-8859-1?Q?Sch=F6lling?= <manuel.schoelling@gmx.de>
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On Sat, May 17, 2014 at 05:00:18PM +0200, Manuel Sch=F6lling wrote:
> Initializations like 'char *foo =3D "bar"' will create two variables:=
 a static
> string and a pointer (foo) to that static string. Instead 'char foo[]=
 =3D "bar"'
> will declare a single variable and will end up in shorter
> assembly (according to Jeff Garzik on the KernelJanitor's TODO list).

The hell it will.  Compare assembler generated e.g. for 32bit x86 befor=
e
and after.

>  {
>  	char *dp;
>  	char *status =3D "disabled";
> -	const char * flags =3D "flags: ";
> +	const char flags[] =3D "flags: ";

The first variant puts address of constant array into local variable
(on stack or in a register).  The second one fills local _array_ - the
string itself goes on stack.