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Re: An argument *against* (the liberal use of) references

From "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com>
Newsgroups comp.lang.c++
Subject Re: An argument *against* (the liberal use of) references
Date 2022-12-02 12:58 -0800
Organization A noiseless patient Spider
Message-ID <tmdott$352d1$2@dont-email.me> (permalink)
References (9 earlier) <DZ6iL.6667$jXi9.3798@fx34.iad> <a3cd87b9-578b-4ec9-8111-2f70eb5e985cn@googlegroups.com> <e4oiL.36061$f9D6.33011@fx09.iad> <tmdn7j$352d1$1@dont-email.me> <iDtiL.87934$Q0m1.45700@fx18.iad>

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On 12/2/2022 12:55 PM, Scott Lurndal wrote:
> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
>> On 12/2/2022 6:36 AM, Scott Lurndal wrote:
>>> Michael S <already5chosen@yahoo.com> writes:
>>>> On Thursday, December 1, 2022 at 9:09:39 PM UTC+2, Scott Lurndal wrote:
>>>>> Paavo Helde <ees...@osa.pri.ee> writes:
>>>>>> 01.12.2022 18:02 Scott Lurndal kirjutas:
>>>>>>> Paavo Helde <ees...@osa.pri.ee> writes:
>>>>>>>> 01.12.2022 15:06 Stuart Redmann kirjutas:
>>>>>>>
>>>
>>>>>
>>>>> In legacy Intel/AMD systems, where the LOCK prefix is being used, the
>>>>> systemwide lock is the only possibility [*].
>>>>>
>>>>
>>>> Huh?
>>>> There is absolute no relationship between what prefix is used (instruction
>>>> encoding issue) and implementation.
>>>
>>> The only way to specify an atomic access in those chips was
>>> to use the LOCK prefix (e.g. LOCK ADD generates an atomic
>>> add, et alia).
>>>
>>
>> Iirc, XCHG has an implicit LOCK prefix?
> 
> Not sure about XCHG, but CMPXCHG requires the prefix
> when used in a multiprocessor system; on a uniprocessor
> it will be atomic because interrupts are always taken
> between instructions (unlike, the VAX, for instance,
> where certain instructions (MOVC3/5) can be interrupted
> and restarted).    I suspect that XCHG has similar
> characteristics.
> 
> 

Iirc, XCHG is the _only_ atomic RMW instruction that has an _implicit_ 
LOCK prefix. CMPXCHG _needs_ the programmer to put in a LOCK prefix.

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An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-11-22 09:52 +0000
  Re: An argument *against* (the liberal use of) references "Fred. Zwarts" <F.Zwarts@KVI.nl> - 2022-11-22 11:23 +0100
  Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-11-22 13:27 +0200
    Re: An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-11-23 06:52 +0000
      Re: An argument *against* (the liberal use of) references "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-23 13:51 +0100
        Re: An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-11-23 13:46 +0000
          Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-11-30 13:59 +0200
            Re: An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-12-01 06:45 +0000
              Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-01 09:19 +0200
                Re: An argument *against* (the liberal use of) references Stuart Redmann <DerTopper@web.de> - 2022-12-01 14:06 +0100
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-01 16:45 +0200
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-01 16:02 +0000
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-01 20:21 +0200
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-01 19:09 +0000
                Re: An argument *against* (the liberal use of) references Michael S <already5chosen@yahoo.com> - 2022-12-02 05:53 -0800
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-02 14:36 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-02 12:29 -0800
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-02 20:55 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-02 12:58 -0800
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-02 21:18 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-02 14:16 -0800
                Re: An argument *against* (the liberal use of) references Branimir Maksimovic <branimir.maksimovic@icloud.com> - 2022-12-02 21:09 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-02 13:22 -0800
                Re: An argument *against* (the liberal use of) references Branimir Maksimovic <branimir.maksimovic@icloud.com> - 2022-12-02 21:36 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-02 14:13 -0800
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-02 18:33 +0200
                Re: An argument *against* (the liberal use of) references Michael S <already5chosen@yahoo.com> - 2022-12-01 11:59 -0800
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-01 23:53 +0200
                Re: An argument *against* (the liberal use of) references Michael S <already5chosen@yahoo.com> - 2022-12-02 04:11 -0800
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-01 12:21 -0800
                Re: An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-12-06 11:36 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-06 12:26 -0800
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-06 20:39 +0000
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-06 23:53 +0200
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-06 13:59 -0800
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-06 22:04 +0000
                Re: An argument *against* (the liberal use of) references Öö Tiib <ootiib@hot.ee> - 2022-12-06 21:38 -0800
                Re: An argument *against* (the liberal use of) references scott@slp53.sl.home (Scott Lurndal) - 2022-12-07 15:22 +0000
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-07 18:37 +0200
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-06 14:01 -0800
                Re: An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-12-07 09:05 +0000
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-07 12:48 -0800
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-07 12:50 -0800
                Re: An argument *against* (the liberal use of) references Juha Nieminen <nospam@thanks.invalid> - 2022-12-08 07:52 +0000
                Re: An argument *against* (the liberal use of) references Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-08 05:50 -0800
                Re: An argument *against* (the liberal use of) references Michael S <already5chosen@yahoo.com> - 2022-12-08 13:30 -0800
                Re: An argument *against* (the liberal use of) references Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-09 12:50 -0800
                Re: An argument *against* (the liberal use of) references David Brown <david.brown@hesbynett.no> - 2022-12-11 12:18 +0100
                Re: An argument *against* (the liberal use of) references Paavo Helde <eesnimi@osa.pri.ee> - 2022-12-08 13:38 +0200
                Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-12-08 16:45 -0800
                Re: An argument *against* (the liberal use of) references Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-12-09 04:35 -0800
  Re: An argument *against* (the liberal use of) references Bonita Montero <Bonita.Montero@gmail.com> - 2022-11-22 15:36 +0100
  Re: An argument *against* (the liberal use of) references Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2022-11-22 15:21 +0000
  Re: An argument *against* (the liberal use of) references Richard Damon <Richard@Damon-Family.org> - 2022-11-22 10:48 -0500
    Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-22 13:18 -0800
  Re: An argument *against* (the liberal use of) references El Jo <giorgio.zoppi@gmail.com> - 2022-11-22 13:41 -0800
    Re: An argument *against* (the liberal use of) references "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-22 13:51 -0800
  Re: An argument *against* (the liberal use of) references Bonita Montero <Bonita.Montero@gmail.com> - 2022-11-23 20:08 +0100

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