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Re: Are rotating register files still a bad idea?

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.arch
Subject Re: Are rotating register files still a bad idea?
Date 2012-02-06 12:49 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2012Feb6.134944@mips.complang.tuwien.ac.at> (permalink)
References <ggtgp-A1F9BB.02163102022012@netnews.mchsi.com> <4F2CD63A.4050306@SPAM.comp-arch.net> <ggtgp-25AEB5.07151604022012@netnews.mchsi.com> <4F2EF96A.1040107@SPAM.comp-arch.net>

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"Andy (Super) Glew" <andy@SPAM.comp-arch.net> writes:
>Register windows, on the other hand, increase the number of registers 
>that need to be renamed. This was a killer for Itanium.  I tried playing 
>games such as renaming only the currently accessible registers (on 
>Itanium even that was a lot), or the top few procedure contexts, 
>stalling until retirement and renaming had settled down if you called 
>and returned too quickly.  But this forces you into a copy at retirement 
>model.

Sure, IA-64 allows the implementation to have more register names
through the register stack, but it does not force it, and I really
don't see that their absence is a "killer".  IIRC there are 96 (or was
it 128?)  register names visible for the register stack.  This should
be plenty for lots of code.  And for code where the call stacks are so
deep, with so many parameters and locals, that additional register
names would provide a significant benefit, even an implementation
without the additional names would still be at least as good as (and
probably better than) architectures without register stack/register
windows.  Or am I missing something?

- anton
-- 
M. Anton Ertl                    Some things have to be seen to be believed
anton@mips.complang.tuwien.ac.at Most things have to be believed to be seen
http://www.complang.tuwien.ac.at/anton/home.html

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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? Glen Overby <coreSPAMsample@charter.net> - 2012-03-01 18:18 -0600
            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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