On Thu, Nov 2, 2017 at 1:49 PM, Szabolcs Nagy <szabolcs.n...@arm.com> wrote: > On 01/11/17 16:47, Szabolcs Nagy wrote: >> On 01/11/17 16:26, Jakub Jelinek wrote: >>> On Wed, Nov 01, 2017 at 04:23:11PM +0000, Szabolcs Nagy wrote: >>>> is there a way to get vectorized math functions in fortran? >>>> >>>> in c code there is attribute simd declarations or openmp >>>> declare simd pragma to tell the compiler which functions >>>> have simd variant, but i see no such thing in fortran. >>> >>> !$omp declare simd should work fine in fortran (with -fopenmp >>> or -fopenmp-simd). >>> >> >> 1) i don't want to change the fortran. >> >> 2) it does not work for me. >> >> i want this to call vector powf in libmvec: >> >> subroutine foo(a,b,c) >> real(4) a(8000),b(8000),c(8000) >> do j=1,8000 >> a(j)=b(j)**c(j) >> end do >> end >> >> where do i put >> >> !$omp declare simd (powf) >> >> ? > > to answer my question.. > > it seems fortran cannot express the type signature > of mathematical functions because arguments are > passed by reference. > > so there is no way to declare math interfaces > and then add omp declare simd to them to get > simd versions.
Not even with BIND(C) or so? > (it's not clear to me how omp declare simd is > supposed to work in fortran, but it is not useful > for vectorizing loops with math functions.) > > so gfortran will need a different mechanism to > do the vectorization, e.g. an option like > -mveclibabi=glibc, but the list of available > vector functions need to be specified somewhere. I think most useful would be if glibc ships with a fortran module that provides the appropriate declarations and users can simply include such module or such module would be automagically included like we have that C pre-def header. Of course first we have to solve the mystery of how to actually declare the libm sin() function in the appropriate way. And if there isn't one, provide one by means of an extension ($! pragma gcc whatever?) Richard.
