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From: Oleh Derevenko <oleh.derevenko@gmail.com>
Date: Thu, 4 Nov 2021 11:44:52 +0200
Message-ID: <CAC1wWD2NnXMz2Yr72x+OSu54j6cXDzmad6bpEPYEKJ5m54BfOw@mail.gmail.com>
Subject: Re: [PATCH] x86: Optimize atomic_compare_and_exchange_[val|bool]_acq
 [BZ #28537]
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>, 
 Arjan van de Ven via Libc-alpha <libc-alpha@sourceware.org>,
 Arjan van de Ven <arjan@linux.intel.com>
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Hi

On Thu, Nov 4, 2021 at 10:58 AM Oleh Derevenko <oleh.derevenko@gmail.com> wrote:
> Also, another problem, blindly taking
>  __typeof (*(mem)) oldmem = ...
> could declare the "oldmem" variable with const and/or volatile
> (depending on the actual parameter to the macro) and make either an
> assignment to const (a compile error) or an assignment to volatile
> (unnecessary forced store into memory with following retrieval from
> there).

Well, const cannot appear in the target, of course. But volatile can.

-- 

Oleh Derevenko
-- Skype with underscore