Date: Mon, 03 Jan 2000 20:29:00 -0800 From: "Ronald F. Guilmette" <rfg@monkeys.com> To: root@ihack.net (Charles M. Hannum) Cc: freebsd-hackers@FreeBSD.ORG, Markus Holmberg <saska@acc.umu.se>, briano@netscape.com, gatgul@voicenet.com, brendan@mozilla.org, waldemar@netscape.com, daeron@Wit401305.student.utwente.nl, clayton@netscape.com, mccabe@netscape.com Subject: Re: Should -mieee-fp equal fpsetmask(0) to avoid SIGFPE on FreeBSD? Message-ID: <61713.946960140@monkeys.com> In-Reply-To: Your message of 03 Jan 2000 23:19:02 -0500. <el2r9fysc3s.fsf@eniwetok.ihack.net>
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In message <el2r9fysc3s.fsf@eniwetok.ihack.net>, you wrote: > >"Ronald F. Guilmette" <rfg@monkeys.com> writes: > >> >Question 1: What is the reason for FreeBSD to differ from other platforms >> >and not follow the IEEE standard by default? >> >(Please forgive me if this is an ignorant question.) >> >> No, its a Good Question, and I'd like to know the answer also. > >That's actually a trick question. When I researched this a few years >ago, I found that *no* system other than NetBSD starts up in an >IEEE-conformant mode. To wit: > >* iBCS2/SCO, SVR4 and FreeBSD leave exceptions unmasked. > >* Linux uses the Intel default control word, which sets extended > precision mode (which is not IEEE conformant). Well, when *I* researched it a few years ago, I seem to recall that about 2/3rds of the systems I tested at that time did in fact properly disable all of the FP traps prior to entry into main(). I think that the commercial/proprietary systems were generally pretty good about doing this, e.g. Solaris, IRIX, HP/UX, DG/UX, DEC/OSF/1, etc. But I think that you are correct that SCO was one of the ones that didn't pass the test. Part of the problem is that the major commercial C/C++ compiler test suites make it a point to *only* test for ANSI/ISO conformance... IEEE 754 confor- mance is outside of their scope as far as they are concerned. The result is that a lot of people never do any serious testing of their C/C++ compilers for IEEE 754 conformance. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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