From: Richard Guenther <richard.guenther@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ulrich Drepper <drepper@gmail.com>, gcc@gcc.gnu.org
Subject: Re: asm in inline function invalidating function attributes?
Date: Mon, 17 Oct 2011 11:11:00 -0000 [thread overview]
Message-ID: <CAFiYyc17q7SwKHr9ax_QctbZOFzdsUHv3JqTi+0gZauZnd=3SQ@mail.gmail.com> (raw)
In-Reply-To: <m2wrc4zey3.fsf@firstfloor.org>
On Mon, Oct 17, 2011 at 1:36 AM, Andi Kleen <andi@firstfloor.org> wrote:
> Ulrich Drepper <drepper@gmail.com> writes:
>>
>> It's not guaranteed to work in general. The problem to solve is that
>> I know the function which is called is not clobbering any registers.
>> If I leave it with the normal function call gcc has to spill
>> registers. If I can hide the function call the generated code can be
>> significantly better.
>
> iirc the new shrink wrapping support that just went in was to address
> problems like that. Perhaps try a mainline compiler?
>
> But I agree that such an attribute would be useful. I would use it.
>
> At least the Linux kernel has a couple such cases ("nasty inline asm to
> hide register clobbering in calls") and it's always ugly and hard to
> maintain.
It would simply be an alternate ABI that makes all registers callee-saved?
I suppose that would be not too hard to add.
Richard.
> -Andi
> --
> ak@linux.intel.com -- Speaking for myself only
>
next prev parent reply other threads:[~2011-10-17 6:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-16 3:29 Ulrich Drepper
2011-10-16 18:52 ` Richard Guenther
2011-10-16 23:37 ` Ulrich Drepper
2011-10-17 8:53 ` Andi Kleen
2011-10-17 11:11 ` Richard Guenther [this message]
2011-10-17 16:20 ` Ulrich Drepper
2011-10-17 16:28 ` Andi Kleen
2011-10-17 4:08 ` Jakub Jelinek
2011-10-17 6:57 ` Ulrich Drepper
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