Article View: comp.arch
Article #20628Re: RISC vs unaligned data
From: John Mashey
Date: Tue, 04 Apr 1989 04:09
Date: Tue, 04 Apr 1989 04:09
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1605 bytes
In article <9931@polyslo.CalPoly.EDU> cquenel@polyslo.CalPoly.EDU (46 more school days) writes:
>In article <16407@winchester.mips.COM> mash@mips.COM (John Mashey) writes:
>>Of course, if N == 100 (if you were doing it with exceptions, perhaps),
>>you now get + 5-15, i.e., 6-16X slower, which is clearly ungood, and
>>only survivable for debugging.
>
> Wait a sec, aren't you comparing the proverbial
> mis-matched fruits here ?
....
> Using exceptions to handle mis-aligned data isn't
> quite as bad as your (admittedly back-of-the-envelope)
> figure of 6-16X would suggest.
Good point! It's certainly not as bad as that in practice. I can't remember
how bad it really was in practice, except that we had a lot of pressure
to get the compiler support in, AFTER the handle-by-exception code was
already in use.
--
-john mashey DISCLAIMER: <generic disclaimer, I speak for me only, etc>
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!vsi1!wyse!mips!mash From: mash@mips.COM (John Mashey) Newsgroups: comp.arch Subject: Re: RISC vs unaligned data Message-ID: <16541@winchester.mips.COM> Date: 4 Apr 89 04:09:30 GMT References: <355@bnr-fos.UUCP> <13@microsoft.UUCP> <16058@cup.portal.com> <370@bnr-fos.UUCP> <11222@tekecs.GWD.TEK.COM> <16407@winchester.mips.COM> <9931@polyslo.CalPoly.EDU> Reply-To: mash@mips.COM (John Mashey) Organization: MIPS Computer Systems, Sunnyvale, CA Lines: 22