Re: libmvec, non-finites and fast-math

[Julian Taylor <jtaylor dot debian at googlemail dot com>]

On 02.08.2016 19:14, Joseph Myers wrote:
> On Tue, 2 Aug 2016, Julian Taylor wrote:
> 
>> On 02.08.2016 17:52, Joseph Myers wrote:
>>> On Tue, 2 Aug 2016, Julian Taylor wrote:
>>>
>>>> So now how to solve this problem. My suggestion would be to relax the
>>>> requirements for vectorizing the math functions to -funsafe-math-optimizations
>>>> instead of -ffast-math, at least when glibc or svml are the backends.
>>>
>>> There is currently no GCC predefined macro for 
>>> -funsafe-math-optimizations, so such a condition is not possible with 
>>> current GCC.
>>>
>>
>> It is GCC that decides to use the vectorized function in the first place
>> so that should not be a problem. Or am I misunderstanding how these
>> functions get called?
> 
> See the __FAST_MATH__ conditional in sysdeps/x86/fpu/bits/math-vector.h.
> 

ah its not declared simd when the flag is not set, makes sense.
Here finer grained control would be very nice, I guess I'll bring that
up in the GCC bugzilla (if it has not already been).

But the finite issue still needs resolving in glibc itself. I can
possibly try creating a patch if you think my proposal can work.