Hi!
Jakub Jelinek wrote:
This patch attempts to implement first part of Fortran OpenMP 4.0 support,
The testsuite coverage could certainly be improved, volunteers for that
and/or bugreports will be certainly appreciated. Don't know how to actually
test aligned clauses, is there any way (except for doing allocations in
C/C++ on the side) to allocate objects on aligned boundaries (aligned
attribute, some way to dynamically allocate aligned storage, ...)?
Fortran - as also C and C++ - does not provide much support for aligned
memory. [Well, C++ has now alignas and align(ment_)of.] But contrary to
C/C++, using library functions for dynamic allocation is more difficult
and gfortran doesn't support GCC's align attribute for non-heap
allocation. I only know of one commercial compiler, which has alignment
directives (for static and dynamically allocated memory). I also was
considering adding support for it - but I haven't found the time to do
so, yet.
Thus, you can either do the allocation in C/C++, call the C function
directly (but requires a manually written interface), or manually align
the memory - e.g. by checking the address and adding an offset.
Actually, the latter might be the simplest: Allocate - statically or
dynamically - the memory somewhere - and calculate the offset. For instance:
use iso_c_binding
implicit none
integer :: array(1024), y ! Or dynamically allocated
integer(c_ptrdiff_t) :: offset, byte_size
integer, parameter :: ALIGNVALUE = 128
offset = ALIGNVALUE - mod (loc (array), ALIGNVALUE)
if (offset == ALIGNVALUE) &
offset = 0
offset = offset/c_sizeof(y)
call some_subroutine(array(1+offset:))
contains
subroutine some_subroutine(x)
integer :: x(:)
if (mod (loc(x), ALIGNVALUE) /= 0) &
call abort()
end subroutine some_subroutine
end
(Side remark: The code uses "loc()" which is a vendor extension; C_LOC()
can also be used, but that requires the target or pointer attribute.)
Bootstrapped/regtested on x86_64-linux and i686-linux. Any comments on
this?
Looks good to me - not that I checked every line. One small nit below.
+/* For use in OpenMP clauses in case we need extra information
+ (aligned clause alignment, linear clause step, etc. */
The ")" is missing in the comment.
* * *
BTW: I think it would be nice to have a better error message for the
following:
! ---------------------------------------
integer :: a(10) = [1,2,3,4,5,6,7,8,9,0]
integer :: i
!$omp simd safelen(i) linear(a:2) safelen(i)
do i = 1, 5
end do
end
! ---------------------------------------
It currently fails with:
Error: Unclassifiable OpenMP directive at (1)
but the only problem is that there are two "safelen".
With C, one gets a better message:
foo.c:6:25: error: too many 'safelen' clauses
Question is the following valid or not?
void test() {
int a[10];
int i;
#pragma omp simd linear(a:2) safelen(i)
for (i = 1; i < 5; i++)
;
}
It is rejected with:
foo.c:5:24: error: linear clause applied to non-integral non-pointer
variable with type 'int[10]'
Tobias
