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Re: [PATCH, i386]: Implement atomic_fetch_sub

From: Richard Henderson <rth at redhat dot com>
To: Uros Bizjak <ubizjak at gmail dot com>
Cc: Richard Guenther <richard dot guenther at gmail dot com>, gcc-patches at gcc dot gnu dot org
Date: Fri, 03 Aug 2012 07:40:17 -0700
Subject: Re: [PATCH, i386]: Implement atomic_fetch_sub
References: <CAFULd4ZG8hH20HR0Dix5i7C0hVz7Bm4jvmMPH9UjZYn_5gzSxw@mail.gmail.com> <CAFULd4Yna7o-BFv5CfyZQ6NnKMMyYAnO-FxnNBpOgk1LA=yo_g@mail.gmail.com> <CAFiYyc1FP6oYLh5wFe1Wk0usSUsOct1OUj+r3SqesR2-NU4wGA@mail.gmail.com> <CAFULd4agPWhPKr6DM+2uooCpMdr8tWsoUkDDKMW=bdsKCR4qBQ@mail.gmail.com>

On 2012-08-03 01:51, Uros Bizjak wrote:
> The same reasoning goes for dynamic negation: for neg %eax,%eax value
> 0x80000000 stays the same, but we have changed (x)sub to an (x)add in
> the code stream.

So?  Did you think the xadd will trap?


r~

Follow-Ups:
- Re: [PATCH, i386]: Implement atomic_fetch_sub
  - From: Uros Bizjak
- Re: [PATCH, i386]: Implement atomic_fetch_sub
  - From: Andrew MacLeod

References:
- [PATCH, i386]: Implement atomic_fetch_sub
  - From: Uros Bizjak
- Re: [PATCH, i386]: Implement atomic_fetch_sub
  - From: Uros Bizjak
- Re: [PATCH, i386]: Implement atomic_fetch_sub
  - From: Richard Guenther
- Re: [PATCH, i386]: Implement atomic_fetch_sub
  - From: Uros Bizjak

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