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[Bug middle-end/31723] Use reciprocal and reciprocal square root with -ffast-math
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 11 Jun 2007 05:51:43 -0000
- Subject: [Bug middle-end/31723] Use reciprocal and reciprocal square root with -ffast-math
- References: <bug-31723-11659@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #23 from ubizjak at gmail dot com 2007-06-11 05:51 -------
(In reply to comment #22)
> At some point icc did such transformations (for 1/x and sqrt) but, apparently,
> they're now removed. It didn't bother to plug every holes (ie wrt infinities)
> but at least got the case of 0 covered even when set lose; it's cheap to do.
> I've repeatedly been pointed to the peculiar semantic of -ffast-math in the
> past, so i know there's little chance for me to succeed, but would it be
> possible to consider that as an option?
But both, rcpss and rsqrtss handle infinties correctly (they return zero) and
return [-]inf when [-]0.0 is used as an argument.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31723