Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ames.arc.nasa.gov!lamaster
From: lamaster@ames.arc.nasa.gov (Hugh LaMaster)
Newsgroups: comp.arch
Subject: Re: (Im)precise exceptions
Message-ID: <33004@ames.arc.nasa.gov>
Date: 4 Oct 89 20:02:32 GMT
References: <2353@oakhill.UUCP> <261500010@S34.Prime.COM> <34701@apple.Apple.COM> <2451@wyse.wyse.com> <477@ctycal.UUCP> <265@ssp1.idca.tds.philips.nl> <4796@orca.WV.TEK.COM> <27659@shemp.CS.UCLA.EDU> <269@ssp1.idca.tds.philips.nl> <28764@winchester.mips.COM>
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In article <28764@winchester.mips.COM> mash@mips.COM (John Mashey) writes:
>Bottom line:
>	Precise exceptions are precise; truly imprecise ones are rare;
>	there's a wide variation in the middle of the effort needed to
>	make them look precise.

Of course, the CDC 7600 had not
only imprecise exceptions, but also "delayed exceptions" (is there a
name) when certain floating point conditions produced an indefinite,
which was an *error* at the point you *used* it in another operation,
millions of instructions later...

I don't remember imprecise exceptions being that big a deal, although
it did create a small cottage industry for debugging certain difficult
programs :-)


  Hugh LaMaster, m/s 233-9,  UUCP ames!lamaster
  NASA Ames Research Center  ARPA lamaster@ames.arc.nasa.gov
  Moffett Field, CA 94035     
  Phone:  (415)694-6117