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! Exercise three levels of parallelism using SGEMM from BLAS.
! { dg-do run }
! Explicitly set vector_length to 128 using a vector_length clause.
subroutine openacc_sgemm_128 (m, n, k, alpha, a, b, beta, c)
integer :: m, n, k
real :: alpha, beta
real :: a(k,*), b(k,*), c(m,*)
integer :: i, j, l
real :: temp
!$acc parallel loop copy(c(1:m,1:n)) copyin(a(1:k,1:m),b(1:k,1:n)) vector_length (128) firstprivate (temp)
do j = 1, n
!$acc loop
do i = 1, m
temp = 0.0
!$acc loop reduction(+:temp)
do l = 1, k
temp = temp + a(l,i)*b(l,j)
end do
if(beta == 0.0) then
c(i,j) = alpha*temp
else
c(i,j) = alpha*temp + beta*c(i,j)
end if
end do
end do
end subroutine openacc_sgemm_128
subroutine host_sgemm (m, n, k, alpha, a, b, beta, c)
integer :: m, n, k
real :: alpha, beta
real :: a(k,*), b(k,*), c(m,*)
integer :: i, j, l
real :: temp
do j = 1, n
do i = 1, m
temp = 0.0
do l = 1, k
temp = temp + a(l,i)*b(l,j)
end do
if(beta == 0.0) then
c(i,j) = alpha*temp
else
c(i,j) = alpha*temp + beta*c(i,j)
end if
end do
end do
end subroutine host_sgemm
program main
integer, parameter :: M = 100, N = 50, K = 2000
real :: a(K, M), b(K, N), c(M, N), d (M, N), e (M, N)
real alpha, beta
integer i, j
a(:,:) = 1.0
b(:,:) = 0.25
c(:,:) = 0.0
d(:,:) = 0.0
e(:,:) = 0.0
alpha = 1.05
beta = 1.25
call openacc_sgemm_128 (M, N, K, alpha, a, b, beta, d)
call host_sgemm (M, N, K, alpha, a, b, beta, e)
do i = 1, m
do j = 1, n
if (d(i,j) /= e(i,j)) call abort
end do
end do
end program main
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