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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: GNAT 4.8 atomic access to 64-bit objects
Date: Fri, 15 Nov 2013 09:44:41 +0100
Organization: cbb software GmbH
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 <87k3gahgdp.fsf@ludovic-brenta.org>
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Date: 2013-11-15T09:44:41+01:00
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On Thu, 14 Nov 2013 21:34:26 +0100, Ludovic Brenta wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>> The following does not compile anymore for 32-bit Linux targets, e.g. under
>> Debian:
>>
>> procedure Test is
>>    type T is mod 2**64;
>>    X : T;
>>    pragma Atomic (X); -- Error
>> begin
>>    null;
>> end Test;
>>
>> The above seems no more legal, because the compiler does not support
>> atomic access to X.
>>
>> Is there a way to change this without machine code insertions?
> 
> Even with machine code insertions, I fail to see how a 32-bit processor
> can accept 64-bit integers as atomic.

  movq ?

(the target is not an i386)

> I'd suggest you use 64-bit floating-point registers instead; i386
> processors have them, I think.  That has been a useful trick for a
> decade or so :)

Using unchecked union or unchecked conversion?

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de