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Re: Does each core of 8-core Intel processor has an independent floating X87 unit?

From BGB <cr88192@hotmail.com>
Newsgroups comp.lang.c
Subject Re: Does each core of 8-core Intel processor has an independent floating X87 unit?
Date 2015-04-05 11:43 -0500
Organization albasani.net
Message-ID <mfrouj$nl2$1@news.albasani.net> (permalink)
References <0c864744-32bf-4ce9-8b2e-f2a842fec7bb@googlegroups.com> <mfrjl7$k2k$1@dont-email.me> <mfrmlp$jjp$1@news.albasani.net> <20150405182032.3fc6cd95@maxa-pc>

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On 4/5/2015 11:20 AM, Melzzzzz wrote:
> On Sun, 05 Apr 2015 11:04:53 -0500
> BGB <cr88192@hotmail.com> wrote:
>
>> On 4/5/2015 10:17 AM, Noob wrote:
>>> On 05/04/2015 15:50, Weng Tianxiang wrote:
>>>
>>>> Does each core of 8-core Intel processor have an independent
>>>> floating X87 unit?
>>>
>>> comp.lang.c discusses the C programming language. Your question
>>> is waaay off-topic. The comp.arch newsgroup might help you.
>>>
>>> This in-depth review answers your question:
>>> http://www.realworldtech.com/haswell-cpu/
>>>
>>> And x87 is obsolete.
>>>
>>
>> FWIW though, typically normal apps only use floating point rarely
>> (primarily or integer-only code is significantly more common), and
>> many newer apps assume using SSE for all their floating-point stuff
>> (as pretty much any processor made in the past decade or so supports
>> SSE2 or better).
>>
>> so, there isn't really much need for each core to have a dedicated
>> x87 unit.
>>
>>
>> it is possible that if 16 and 32-bit code went away, the x87 FPU
>> could possibly also go away along with it (as the 64-bit ABIs
>> generally disallow use of x87, setting SSE2 as the minimum).
>
> Since when?
>

AFAIK, this was an interpretation at least early on for the Win64 ABI, 
as-in, you are generally not supposed to use x87.

the ABI also treats it as volatile, and is not necessarily preserved 
across context switches (though IME is preserved at least for Ring-3 
WoW64 processes).


however, SysV/AMD64 still specifies x87 as existing, and x87 state is 
preserved, though SSE is primarily used for passing/returning values.

in both cases though, x87 instructions still work though, and it would 
likely still pose a problem for some existing code if x87 support were 
removed.


but, by the time someone got around to making a 64-bit only CPU, it is 
likely x87 would be mostly dead and gone by that point, and any code 
depending on the x87 FPU would be treated about like how 16-bit 
applications were treated in the move to 64-bit Windows.

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Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-05 06:50 -0700
  Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Noob <root@127.0.0.1> - 2015-04-05 17:17 +0200
    Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 17:35 +0200
      Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:21 -0500
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 18:40 +0200
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:56 -0500
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 10:08 -0700
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 13:17 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:10 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 10:26 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 23:40 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Bartc <bc@freeuk.com> - 2015-04-07 23:06 +0100
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-08 01:23 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 23:15 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 20:16 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-08 09:27 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-08 09:44 -0500
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 19:37 +0200
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 18:50 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-05 22:29 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 23:09 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 01:54 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 07:44 -0500
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:16 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 03:32 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 12:48 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Richard Heathfield <rjh@cpax.org.uk> - 2015-04-07 11:57 +0100
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 13:33 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 15:21 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-07 17:15 +0000
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Tim Prince <tprince@computer.org> - 2015-04-07 14:21 -0400
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:08 -0700
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 15:27 -0500
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Noob <root@127.0.0.1> - 2015-04-05 19:04 +0200
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 19:38 +0200
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 10:46 -0700
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:12 -0700
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 09:51 -0700
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 12:18 -0500
      Re: Does each core of 8-core Intel processor has an independent floating X87 unit? jacobnavia <jacob@jacob.remcomp.fr> - 2015-04-06 01:30 +0200
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 19:27 -0500
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? christian.bau@cbau.wanadoo.co.uk - 2015-04-07 23:58 -0700
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-08 08:08 -0500
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-06 03:36 +0200
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:27 +0200
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 10:39 -0500
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? christian.bau@cbau.wanadoo.co.uk - 2015-04-07 23:47 -0700
    Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:04 -0500
      Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 18:20 +0200
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:43 -0500
      Re: Does each core of 8-core Intel processor has an independent floating X87 unit? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-05 20:28 +0000
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-05 14:46 -0700
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 15:01 -0700
    Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:17 -0700
  Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-05 14:31 -0400
    Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 11:01 +0200
  Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-05 22:34 -0500
    Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-05 23:39 -0700
      Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 02:06 -0500
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 08:57 -0500
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:38 -0500
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 16:30 -0500
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-06 17:10 -0500
                Re: Does each core of 8-core Intel processor has an independent floating   X87 unit? Ian Collins <ian-news@hotmail.com> - 2015-04-07 10:16 +1200
                Re: Does each core of 8-core Intel processor has an independent floating   X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-07 02:23 +0200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 17:36 -0500
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 17:41 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 20:09 -0500
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Richard Damon <Richard@Damon-Family.org> - 2015-04-06 22:44 -0400
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 11:11 +0200
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-06 08:04 -0700
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:43 -0500
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-06 14:52 -0400
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 17:09 -0500
      Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-06 11:11 -0400
        Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:47 -0500
          Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-06 17:15 -0500
            Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 03:41 -0500
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Ian Collins <ian-news@hotmail.com> - 2015-04-07 21:19 +1200
                Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-07 10:37 -0500
                Re: Does each core of 8-core Intel processor has an independent floating   X87 unit? Tim Prince <tprince@computer.org> - 2015-04-07 12:13 -0400
                Re: Does each core of 8-core Intel processor has an independent floating   X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-09 12:34 -0500
              Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-07 10:48 -0500

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