Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor 64-bit division, etc.

glen herrmannsfeldt <gah@ugcs.caltech.edu>
15 May 2005 17:26:38 -0400

          From comp.compilers

Related articles
[2 earlier articles]
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor anton@mips.complang.tuwien.ac.at (2005-05-14)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-05-14)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor christian.bau@cbau.freeserve.co.uk (Christian Bau) (2005-05-14)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-05-15)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor anton@mips.complang.tuwien.ac.at (2005-05-15)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor christian.bau@cbau.freeserve.co.uk (Christian Bau) (2005-05-15)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-05-15)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor anton@mips.complang.tuwien.ac.at (2005-05-16)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor Jonathan_Epstein@nih.gov (Jonathan Epstein) (2005-05-16)
Re: 96-bit integer modulo, Athlon64 gcc 64-bit integers, libc codefor Jonathan_Epstein@nih.gov (Jonathan Epstein) (2005-05-20)
| List of all articles for this month |

From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.compilers
Date: 15 May 2005 17:26:38 -0400
Organization: Compilers Central
References: 05-05-063 05-05-082 05-05-098 05-05-108 05-05-116
Keywords: performance

Christian Bau wrote:


> glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:


(snip)


>>Does the OS save the full 64 bit registers when not in 64 bit mode?


(snip)


> or the designers are really really and I mean really
> absolutely incredibly braindamaged stupid. I would assume the first.


The case I was thinking of was running a 32 bit OS on a 64 bit
architecture that is an extension of a 32 bit architecture.


Say, for example, Win2000 on AMD-64 (x86-64). The OS has no idea that
the registers are 64 bits. Unless the hardware includes special mode
bits to stop the operations, the user should be able to use those
bits.


Since one could compile on one machine and run on another, it isn't
enough to check at compile time for a 64 bit OS.


-- glen


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