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From: Adrian Bunk <bunk@stusta.de>
To: Roland Dreier <rdreier@cisco.com>
Cc: Rob Landley <rob@landley.net>,
	Arjan van de Ven <arjan@linux.intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Status of CONFIG_FORCED_INLINING?
Date: Thu, 24 May 2007 20:07:04 +0200	[thread overview]
Message-ID: <20070524180704.GE4470@stusta.de> (raw)
In-Reply-To: <adahcq26r8p.fsf@cisco.com>

On Thu, May 24, 2007 at 10:55:34AM -0700, Roland Dreier wrote:
>  > And if you #include a non-inlined definition in two .c files, the compiler 
>  > will emit two copies into two separate .o files.  What you're hoping is that 
>  > the linker will notice they're identical and merge them, and last I checked I 
>  > couldn't even reliably get it to do that with constant strings.
> 
> No, I don't care if the linker merges it or not.  In fact I hope that
> maybe the compiler is smart enough to optimize the function for the
> sites it's called from in a particular .c file.
> 
> But a function defined in a .h file had better be static, so it
> shouldn't matter if there are two copies of it in the final linked
> image (any more than it matters if there are 100 inlined copies of it).

The problem is that inline functions in headers are intended to be 
called from different C files.

gcc might not inline it in the C files where it is called more than 
once.

But it will always inline it if it's called only once.

One of both will be suboptimal, but from gcc's perspective it was 
optimal.

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed


  reply	other threads:[~2007-05-24 18:07 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-23 19:10 Status of CONFIG_FORCED_INLINING? Rob Landley
2007-05-23 19:42 ` Arjan van de Ven
2007-05-23 21:22   ` Adrian Bunk
2007-05-23 21:28     ` Roland Dreier
2007-05-24 12:38       ` Robert P. J. Day
2007-05-24 16:55         ` Rob Landley
2007-05-24 17:10       ` Adrian Bunk
2007-05-24 17:14         ` Roland Dreier
2007-05-24 17:47           ` Rob Landley
2007-05-24 17:47             ` Arjan van de Ven
2007-05-24 18:14               ` Rob Landley
2007-05-24 17:55             ` Roland Dreier
2007-05-24 18:07               ` Adrian Bunk [this message]
2007-05-24 18:32                 ` Roland Dreier
2007-05-24 22:41                   ` Adrian Bunk
2007-05-24 17:57           ` Adrian Bunk
2007-05-23 21:31     ` Arjan van de Ven
2007-05-24 17:12       ` Adrian Bunk
2007-05-24 16:29     ` Jan Engelhardt
2007-05-24 17:14       ` Adrian Bunk
2007-05-24 17:17         ` Arjan van de Ven
2007-05-24 17:40       ` Rob Landley

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