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Re: Are rotating register files still a bad idea?

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Brett Davis <ggtgp@yahoo.com> wrote:

> Are rotating register files still a bad idea?
> 
> Rotating register files used to mean slow clock speeds.
> SPARC has had competitive clocks for the past decade,
> largely because everyone hit a thermal brick wall...
> 
> I assume that if that brink wall breaks, rotating register files
> are back to being doomed, but that looks unlikely.

SPARC is on the way out for marketing reasons anyway, so whatever the answer
is it is probably academic.

> Does rotating register files buy you anything net after costs,
> or is it just a fiasco in the age of modern OoO pipelines?

From the programmer's view it helps in that it provides a reasonable,
uniform calling convention as opposed to Intel's bucket-o-shit approach
resulting in every OS that uses it having it's own bizarre calling
conventions. Intel also makes assembly coding harder (not that many people
use it nowadays) because of how few registers they have (AMD64 helps a bit
but not enough) and how likely it is to step on one accidentally, since
there isn't an established save/restore sequence or calling
sequence. Looking at it it's easy to see it was a big ad-hoc failure. Not
sure from a performance perspective but as an assembly programmer I like the
uniformity and sensible SPARC approach much more than Intel's chaotic trash
heap. Since 99.9% of code for those two processors is written in C it mostly
doesn't matter since C coders have no idea what goes on under the bonnet.

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Are rotating register files still a bad idea? Brett Davis <ggtgp@yahoo.com> - 2012-02-02 02:16 -0600
  Re: Are rotating register files still a bad idea? "Paul A. Clayton" <paaronclayton@gmail.com> - 2012-02-02 07:41 -0800
  Re: Are rotating register files still a bad idea? Nomen Nescio <nobody@dizum.com> - 2012-02-02 19:04 +0100
    Re: Are rotating register files still a bad idea? Brett Davis <ggtgp@yahoo.com> - 2012-02-02 23:16 -0600
      Re: Are rotating register files still a bad idea? Fritz Wuehler <fritz@spamexpire-201202.rodent.frell.theremailer.net> - 2012-02-03 18:19 +0100
        Re: Are rotating register files still a bad idea? Anne & Lynn Wheeler <lynn@garlic.com> - 2012-02-03 13:09 -0500
          Re: Are rotating register files still a bad idea? Stephen Fuld <SFuld@alumni.cmu.edu.invalid> - 2012-02-03 12:28 -0800
          Re: Are rotating register files still a bad idea? MitchAlsup <MitchAlsup@aol.com> - 2012-02-03 13:04 -0800
        Re: Are rotating register files still a bad idea? Thomas Womack <twomack@chiark.greenend.org.uk> - 2012-02-03 19:15 +0000
          Re: Are rotating register files still a bad idea? Mark Thorson <nospam@sonic.net> - 2012-02-03 13:08 -0800
            Re: Are rotating register files still a bad idea? Thomas Womack <twomack@chiark.greenend.org.uk> - 2012-02-03 22:21 +0000
              Re: Are rotating register files still a bad idea? Mark Thorson <nospam@sonic.net> - 2012-02-03 18:42 -0800
            Re: Are rotating register files still a bad idea? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-02-04 13:26 +0000
            Re: Are rotating register files still a bad idea? Fritz Wuehler <fritz@spamexpire-201202.rodent.frell.theremailer.net> - 2012-02-05 00:58 +0100
          Re: Are rotating register files still a bad idea? Nomen Nescio <nobody@dizum.com> - 2012-02-04 21:00 +0100
            Re: Are rotating register files still a bad idea? Brett Davis <ggtgp@yahoo.com> - 2012-02-05 00:35 -0600
        Re: Are rotating register files still a bad idea? Quadibloc <jsavard@ecn.ab.ca> - 2012-02-03 10:11 -0800
  Re: Are rotating register files still a bad idea? jgk@panix.com (Joe keane) - 2012-02-03 23:20 +0000
  Re: Are rotating register files still a bad idea? "Andy (Super) Glew" <andy@SPAM.comp-arch.net> - 2012-02-03 22:54 -0800
    Re: Are rotating register files still a bad idea? Brett Davis <ggtgp@yahoo.com> - 2012-02-04 07:15 -0600
      Re: Are rotating register files still a bad idea? "Andy (Super) Glew" <andy@SPAM.comp-arch.net> - 2012-02-05 13:49 -0800
        Re: Are rotating register files still a bad idea? Brett Davis <ggtgp@yahoo.com> - 2012-02-06 05:36 -0600
          Re: Are rotating register files still a bad idea? "Andy (Super) Glew" <andy@SPAM.comp-arch.net> - 2012-02-06 18:46 -0800
            Re: Are rotating register files still a bad idea? Brett Davis <ggtgp@yahoo.com> - 2012-02-28 20:02 -0600
        Re: Are rotating register files still a bad idea? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-02-06 12:49 +0000
      Re: Are rotating register files still a bad idea? Quadibloc <jsavard@ecn.ab.ca> - 2012-02-04 11:14 -0800
  Re: Are rotating register files still a bad idea? Michael S <already5chosen@yahoo.com> - 2012-02-03 06:04 -0800
  Re: Are rotating register files still a bad idea? MitchAlsup <MitchAlsup@aol.com> - 2012-02-03 12:20 -0800

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