From: Al Viro <viro@ZenIV.linux.org.uk>
To: "Manuel Schölling" <manuel.schoelling@gmx.de>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fs: Cleanup string initializations (char[] instead of char *)
Date: Sat, 17 May 2014 17:53:45 +0100 [thread overview]
Message-ID: <20140517165345.GG18016@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1400338818-2853-1-git-send-email-manuel.schoelling@gmx.de>
On Sat, May 17, 2014 at 05:00:18PM +0200, Manuel Schölling wrote:
> Initializations like 'char *foo = "bar"' will create two variables: a static
> string and a pointer (foo) to that static string. Instead 'char foo[] = "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 before
and after.
> {
> char *dp;
> char *status = "disabled";
> - const char * flags = "flags: ";
> + const char flags[] = "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.
next prev parent reply other threads:[~2014-05-17 16:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-17 15:00 [PATCH] fs: Cleanup string initializations (char[] instead of char *) Manuel Schölling
2014-05-17 15:44 ` Mateusz Guzik
2014-05-17 17:21 ` Al Viro
2014-05-17 17:58 ` Mateusz Guzik
2014-05-17 16:53 ` Al Viro [this message]
2014-05-18 10:01 ` Manuel Schoelling
2014-05-19 1:51 ` Kevin Easton
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