weird optimization in sin+cos, x86 backend

[Richard Guenther]

On Mon, Feb 13, 2012 at 2:32 PM, Andrew Haley <aph@redhat.com> wrote:
> On 02/13/2012 01:11 PM, Vincent Lefevre wrote:
>> On 2012-02-09 16:01:48 +0000, Andrew Haley wrote:
>>> On 02/09/2012 03:59 PM, Richard Guenther wrote:
>
>>>> Maybe.  Nothing would prevent us from composing from multiple sources
>>>> of course.  crlibm also only provides double precision routines.
>>>
>>> Okay, but the crlibm algorithms could be extended to long
>>> doubles and, presumably, floats.  Where's Vincent Lefevre
>>> when you need him?   :-)
>>
>> I'm a bit late at reading and answering all my mail. :)
>>
>> Our team has new tools to support other precisions, so that
>> long double would be possible.
>>
>> Also note that CRlibm supports the 4 rounding modes, while the
>> IBM Accurate Mathematical Library currently used in glibc behaves
>> erratically (e.g. can even crash) on directed rounding modes.
>
> I think there is some consensus that crlibm is a great place to start
> for correctly-rounded elementary functions.  I think we'd need, or at
> least greatly appreciate, some help from your team.

I agree.  If crlibm can provide a solid basis for a correctly implemented
set of C99 math functions then use it.  It would be nice to have a
GCC linking exception on it though, otherwise static linking or
re-optimizing with LTO will be difficult.

Richard.