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From: slackey@bbn.com (Stan Lackey)
Newsgroups: comp.arch
Subject: Re: IEEE arithmetic (Goldberg paper)
Message-ID: <64885@bbn.BBN.COM>
Date: 27 Jun 91 13:08:29 GMT
References: <9106210542.AA21933@ucbvax.Berkeley.EDU> <1991Jun24.211407.17389@ingres.Ingres.COM>
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Reply-To: slackey@BBN.COM (Stan Lackey)
Organization: Bolt Beranek and Newman Inc., Cambridge MA
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In article <1991Jun24.211407.17389@ingres.Ingres.COM> jpk@Ingres.COM (Jon Krueger) writes:
>jbs@WATSON.IBM.COM (James B. Shearer) writes:
>> Do you disagree that it is undesirable for optimization to affect
>> a program's behavior?
>Yes.
>It is a good and joyful thing, always and everywhere, for
>compilers to expose broken programs.

Many vector machines do summations in different than program order; thus
optimization on vs. off can and does produce different answers.  They
can be very different depending upon the actual numbers.

-Stan