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Re: Irix6 long doubles implemented wrong? (27_io/ostream_inserter_arith)
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: "Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>, gcc-bugs at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org, gcc at gcc dot gnu dot org, libstdc++ at gcc dot gnu dot org, oldham at codesourcery dot com, ro at TechFak dot Uni-Bielefeld dot DE
- Date: 09 Jan 2003 01:48:19 -0200
- Subject: Re: Irix6 long doubles implemented wrong? (27_io/ostream_inserter_arith)
- Organization: GCC Team, Red Hat
- References: <200212170531.AAA15561@caip.rutgers.edu><or4r97diei.fsf@free.redhat.lsd.ic.unicamp.br><orisxmn2fv.fsf@free.redhat.lsd.ic.unicamp.br><oradiw3e9k.fsf@free.redhat.lsd.ic.unicamp.br><200212241434.JAA22361@caip.rutgers.edu><orhed32l12.fsf@free.redhat.lsd.ic.unicamp.br><orwulx34wh.fsf@free.redhat.lsd.ic.unicamp.br><orptrn4lr0.fsf@free.redhat.lsd.ic.unicamp.br><20030107221549.GR12992@redhat.com><orptr7o91e.fsf@free.redhat.lsd.ic.unicamp.br><20030108220455.GC27635@redhat.com>
On Jan 8, 2003, Richard Henderson <rth@redhat.com> wrote:
> On Wed, Jan 08, 2003 at 03:17:49PM -0200, Alexandre Oliva wrote:
>> I've no idea of what LIA-1 is, but it does have as many denormal bits
>> as normal bits, it's just that the minimum exponent for a denormal is
>> higher than that of a plain doubles, since denormals start with the
>> higher double still being normal.
> Huh? No it doesn't. The minimum normalized double-double is
> { DBL_MIN_FLT, 0 }.
Nevermind, I was thinking having a denormal in the lower double would
make the whole thing denormal, but in this case the lower double
definitely isn't denormal.
Anyway, without this hunk, we get an incorrect DENORM_MIN, and tests
fail. DENORM_MIN isn't as low as MIN_FLT / 2**106, and that's the
problem. This was the cleanest way I found to introduce the
possibility of having fewer denorm bits than mantissa bits, which is
exactly the case of this FP format.
Any better suggestions on how to accomplish this? I think claiming we
don't have denormals is not the right answer either.
--
Alexandre Oliva Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist Professional serial bug killer