https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66158
Thomas Koenig <tkoenig at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
--- Comment #2 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Dominique d'Humieres from comment #1)
> Bounds checking is rather cheap. Does the proposed optimization worth the
> work?
It can be quite significant. An example with recent trunk:
ig25@linux-fd1f:~/Krempel/Matmul/Bounds> cat bounds.f90
program main
use foo
implicit none
real, dimension(10,10) :: a, b, c
integer :: i
call random_number(a)
call random_number(b)
do i=1,1000000
call my_matmul(a,b,c)
end do
end program main
ig25@linux-fd1f:~/Krempel/Matmul/Bounds> cat foo.f90
module foo
implicit none
contains
subroutine my_matmul(a,b,c)
real, dimension(:,:), intent(in) :: a, b
real, dimension(:,:), intent(inout) :: c
c = matmul(a,b)
end subroutine my_matmul
end module foo
ig25@linux-fd1f:~/Krempel/Matmul/Bounds> gfortran -O3 -fcheck=bounds foo.f90
bounds.f90 && time ./a.out
real 0m3.281s
user 0m3.277s
sys 0m0.002s
ig25@linux-fd1f:~/Krempel/Matmul/Bounds> gfortran -O3 foo.f90 bounds.f90 &&
time ./a.out
real 0m1.911s
user 0m1.909s
sys 0m0.002s
