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From: Jussi Laako <jussi.laako@kolumbus.fi>
To: vda@port.imtp.ilyichevsk.odessa.ua
Cc: linux-kernel@vger.kernel.org
Subject: Re: Some functions are not inlined by gcc 3.2, resulting code is ugly
Date: 03 Nov 2002 18:17:51 +0200	[thread overview]
Message-ID: <1036340272.26281.5.camel@vaarlahti.uworld> (raw)
In-Reply-To: <200211031125.gA3BP4p27812@Port.imtp.ilyichevsk.odessa.ua>

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On Sun, 2002-11-03 at 18:17, Denis Vlasenko wrote:

Jump target 17e0 is aligned (with nops):

>     17dd:	88 02                	mov    %al,(%edx)
>     17df:	90                   	nop    
>     17e0:	89 d0                	mov    %edx,%eax
>     17e2:	5a                   	pop    %edx

>     17ec:	eb f2                	jmp    17e0 <__constant_memcpy+0x20>

>     17fa:	eb e4                	jmp    17e0 <__constant_memcpy+0x20>

>     1800:	eb de                	jmp    17e0 <__constant_memcpy+0x20>

>     187c:	e9 5f ff ff ff       	jmp    17e0 <__constant_memcpy+0x20>
>     1881:	eb 0d                	jmp    1890 <__constant_memcpy+0xd0>
>     1883:	90                   	nop    
...
>     188f:	90                   	nop    
>     1890:	c1 e9 02             	shr    $0x2,%ecx
>     1893:	89 d7                	mov    %edx,%edi

And also jump target 1890 is aligned.


I think the penalty of few NOPs is smaller than result of jump to
unaligned address. This is especially true with P4 architecture.


	- Jussi Laako

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  reply	other threads:[~2002-11-03 16:11 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-11-03 16:17 Some functions are not inlined by gcc 3.2, resulting code is ugly Denis Vlasenko
2002-11-03 16:17 ` Jussi Laako [this message]
2002-11-04  0:17   ` Denis Vlasenko
2002-11-03 21:28     ` Jussi Laako
2002-11-04 16:00       ` Denis Vlasenko
2002-11-03 18:14 ` Denis Vlasenko
2002-11-03 15:23   ` Martin J. Bligh
2002-11-04  0:23     ` Denis Vlasenko
2002-11-03 15:37   ` Jakub Jelinek
2002-11-03 16:21     ` Alan Cox
2002-11-04  0:20       ` Denis Vlasenko
2002-11-03 20:28         ` Alan Cox
2002-11-04 16:08           ` Denis Vlasenko
2002-11-13  1:28         ` J.A. Magallón
2002-11-13 11:54           ` Denis Vlasenko
2002-11-13 12:48             ` Denis Vlasenko
2002-11-04  1:21       ` Robert Love
2002-11-04 13:41         ` Alan Cox
2002-11-04 22:44           ` Werner Almesberger
2002-11-04 16:04         ` Denis Vlasenko
2002-11-04 11:39           ` Jakub Jelinek
2002-11-13  0:10   ` J.A. Magallón
2002-11-13 12:04     ` Denis Vlasenko

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