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From: Bob Plantz <plantz@cds1.net>
To: gcc-help@gcc.gnu.org
Cc: Andrew Haley <aph@redhat.com>, Robin-Vossen <robin-vossen@hotmail.com>
Subject: Re: GNU C++ Inline Assembler
Date: Tue, 12 Aug 2008 08:56:00 -0000	[thread overview]
Message-ID: <1218508063.5985.7.camel@bob-desktop> (raw)
In-Reply-To: <48A0E23F.EE8BC28C@dessent.net>

On Mon, 2008-08-11 at 18:07 -0700, Brian Dessent wrote:

> Because the MSVC style of inline assembler doesn't allow for specifying
> any constraints such as which registers or stack slots are clobbered. 
> This means that compiler can't assume anything about the state before
> and after the block, it must just throw away all dataflow information it
> had before the block and assume everything was clobbered, leading to
> tons of useless redundant loads/stores.  The GNU style inline asm works
> within the framework of the optimizing compiler, rather than outside it
> by totally going behind it's back.
> 
> Read the long thread that starts here:
> <http://gcc.gnu.org/ml/gcc/2004-05/threads.html#00070>.

Thank you for the explanation and the link. I've never been a Microsoft
programmer, and I haven't used CodeWarrior (Mac PowerPC) for  a long
time. I had forgotten about that technique of inline assembly.

Bob


  reply	other threads:[~2008-08-12  2:29 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-08-10 21:39 Robin-Vossen
2008-08-11  6:37 ` Bob Plantz
2008-08-11 16:35   ` Robin-Vossen
2008-08-11 16:59     ` David Daney
2008-08-11 21:24     ` Andrew Haley
2008-08-12  1:08       ` Bob Plantz
2008-08-12  2:29         ` Brian Dessent
2008-08-12  8:56           ` Bob Plantz [this message]
2008-08-13 17:27             ` Robin-Vossen
2008-08-12 15:26           ` Ian Lance Taylor

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