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From: chased@rbbb.Eng.Sun.COM (David Chase)
Newsgroups: comp.arch
Subject: Re: IEEE arithmetic (Goldberg paper)
Message-ID: <14775@exodus.Eng.Sun.COM>
Date: 8 Jun 91 00:09:36 GMT
References: <9106072346.AA08023@ucbvax.Berkeley.EDU>
Sender: news@exodus.Eng.Sun.COM
Organization: Sun Microsystems, Mt. View, Ca.
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jbs@WATSON.IBM.COM writes:
>If your chip has 80 bit registers I fail to see how you can avoid
>performing 80 bit loads and stores while saving and restoring these registers.

Other people have managed in the past.  Perhaps you are insufficiently
imaginative.  The only problem comes when "machine epsilon" computed
in registers does not match the "machine epsilon" stored in memory.
Otherwise, it is a big help when accumulating into a register (as in
inner product, for example) since the extra bits are most helpful in
guarding against lost precision.

I'm not certain I remember this correctly, but I recall that friends
at Rice had this "problem" with a compiler that they wrote for a
machine called the "PC/RT".  Note that the same problem ("excess
precision") occurs on the RS/6000 in certain situations.

David Chase
Sun