https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96080
--- Comment #2 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
In contrast, see the same example with 'dimension(:)' removed, that is, scalar
data. Here, we see the directives and the runtime library routines behave in
the same way for Fortran 'pointer'.
program main
use openacc
implicit none
integer, target :: data
integer, pointer :: data_p
call acc_create(data) ! h=0x7fffffffd79c, s=4
! NEW
! (gdb) print tgt
! $2 = (struct target_mem_desc *) 0xa7a690
! (gdb) print/x *tgt
! $3 = {refcount = 0x1, array = 0xb18570, tgt_start = 0x7fffcf000000,
tgt_end = 0x7fffcf000004, to_free = 0x7fffcf000000, prev = 0x0, list_count =
0x1, device_descr = 0x80aae0, list = 0xa7a6d0}
! (gdb) print/x tgt->list[0]
! $4 = {key = 0xb18570, copy_from = 0x0, always_copy_from = 0x0,
do_detach = 0x0, offset = 0x0, length = 0x4}
data_p => data
call acc_copyin(data_p) ! h=0x7fffffffd79c, s=4
! This is 'data'!
! (gdb) print n
! $5 = (splay_tree_prefix_splay_tree_key) 0xb18570
! OLD 'data'
! '++dynamic_refcount'
! That means, this does *not* create a new mapping, 'acc_copyin(data_p)'
*does* dereference 'data_p => data'.
! That means, we cannot use this to create a "pointer object 'data_p'" on
the device.
print *, acc_is_present(data_p) ! h=0x7fffffffd79c, s=4
! This is 'data'!
! (gdb) print n
! $6 = (splay_tree_prefix_splay_tree_key) 0xb18570
! Mapped.
!$acc enter data copyin(data_p)
! 0 ("to" '*data_p'), 1 ("pointer assign" 'data_p')
! (gdb) print n
! $8 = (splay_tree_prefix_splay_tree_key) 0xb18570
! OLD 'data'
! '++dynamic_refcount'
print *, acc_is_present(data_p) ! h=0x7fffffffd79c, s=4
! Same as above; mapped.
!$acc serial present(data_p)
! 0 ("force_present" '*data_p')
! (gdb) print n
! $10 = (splay_tree_prefix_splay_tree_key) 0xb18570
! OLD 'data' -- expected
! 1 ("pointer assign" 'data_p')
! [...]
data_p = 55
!$acc end serial
end program main
In contrast to an 'integer, dimension(:), pointer :: data_p', we cannot use an
'integer, pointer :: data_p' to create a "pointer object 'data_p'" on the
device. That's confusing (at least for me). Plus the original confusion about
'acc_on_device' etc. behaving differently (non-sensical?).
