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Re: computing long double NaN on Irix 6.5

From: Eric Blake
Subject: Re: computing long double NaN on Irix 6.5
Date: Fri, 27 Feb 2009 06:48:43 -0700
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According to Bruno Haible on 2/27/2009 6:22 AM:

[adding bug-autoconf, about an Irix 6.5 situation]

>> After the patch, under gcc 3.4.3, 2 tests still fail (probably due to gcc
>> mishandling Irix's weird notion of a 128-bit long double formed by adding
>> two 64-bit doubles together).  It reminds me of a previously fixed MaxOS
>> failure in that area, although I haven't had time to test.  But since the
>> new failures are unrelated to NaN, and since cc passes all 16 tests, I'm
>> committing the patch below.
>> ../../gltests/test-frexpl.c:144: assertion failed
>> /bin/sh[9]: 341777 Abort(coredump)
>> FAIL: test-frexpl
>> ../../gltests/test-ldexpl.c:130: assertion failed
>> /bin/sh[9]: 338455 Abort(coredump)
>> FAIL: test-ldexpl

>   - with CC="gcc", a gcc 2.95.2 I get this failure
> test-floorl.c:82: assertion failed
> /bin/sh[9]: 255782 Abort(coredump)
> FAIL: test-floorl
>     but this is due to a gcc bug: If floorl(-0.7L) is executed before
>     floorl(-1.0L), and both calls are compiled by gcc - regardless whether
>     in the same function, in different functions, or even in different 
> compilation
>     units -, then the floorl(-1.0L) call returns -2L instead of -1L. If at 
> least one
>     of the calls is in a compilation unit compiled by cc, no problem.

What a strange bug!  Obviously, older gcc on Irix is not the best option;
maybe autoconf should default to cc on this platform, rather than always
favoring gcc.  Should we update install.texi (and thus INSTALL) to mention
that on Irix, if gcc doesn't work, to try cc?

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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