This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: One more limits question
- From: Mark Mitchell <mark at codesourcery dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, "gdr at integrable-solutions dot net" <gdr at integrable-solutions dot net>
- Date: Wed, 29 Jan 2003 13:03:05 -0800
- Subject: Re: One more limits question
--On Wednesday, January 29, 2003 12:50:55 PM -0800 Richard Henderson
<rth@redhat.com> wrote:
On Wed, Jan 29, 2003 at 12:39:48PM -0800, Mark Mitchell wrote:
The constant-folding machinery seems to always consider this
expression to evaluate to true, due to this code in fold:
IIRC the plan was that __builtin_nan would produce some
non-nan value on targets that don't support them. I don't
remember off-hand where this happens.
fold_builtin_nan calls real_nan. real_nan calls get_canonical_{q,s}nan
in this case. Those functions seem to be unconditionalized in any
way.
I also see that we have -ftrapping-math, which sets __SUPPORT_SNAN__,
which may or may not be related.
We also have MODE_HAS_NANS, but not MODE_HAS_SIGNALING_NANS.
Do you know a non-signaling-Nan target I could build a cross-compiler
for, so that I could check out how this works?
Thanks,
--
Mark Mitchell mark@codesourcery.com
CodeSourcery, LLC http://www.codesourcery.com