* [Bug fortran/96080] OpenACC/Fortran runtime library routines vs. Fortran 'pointer'
2020-07-06 15:13 [Bug fortran/96080] New: [OpenACC] 'acc_is_present' for Fortran 'pointer' tschwinge at gcc dot gnu.org
@ 2020-07-09 19:30 ` tschwinge at gcc dot gnu.org
2020-07-09 20:00 ` tschwinge at gcc dot gnu.org
2021-07-01 10:15 ` tschwinge at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: tschwinge at gcc dot gnu.org @ 2020-07-09 19:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96080
Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[OpenACC] 'acc_is_present' |OpenACC/Fortran runtime
|for Fortran 'pointer' |library routines vs.
| |Fortran 'pointer'
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
CC| |jakub at gcc dot gnu.org
Last reconfirmed| |2020-07-09
--- Comment #1 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
This problem does *not* seem to be specific to just 'acc_is_present', but
probably all (?) OpenACC/Fortran runtime library routines? Consider the
following transcript, where we see the directives behave as expected for
Fortran 'pointer' to 'dimension(:)', but the runtime library routines do not.
program main
use openacc
implicit none
integer, dimension(:), target :: data(19) ! 19 * 4 = 76 = 0x4c
integer, dimension(:), pointer :: data_p
call acc_create(data) ! h=0x7fffffffd6d0, s=76
! NEW
! (gdb) print tgt
! $2 = (struct target_mem_desc *) 0xa7b690
! (gdb) print/x *tgt
! $3 = {refcount = 0x1, array = 0xb19480, tgt_start = 0x7fffcf000000,
tgt_end = 0x7fffcf00004c, to_free = 0x7fffcf000000, prev = 0x0, list_count =
0x1, device_descr = 0x80bae0, list = 0xa7b6d0}
! (gdb) print/x tgt->list[0]
! $4 = {key = 0xb19480, copy_from = 0x0, always_copy_from = 0x0,
do_detach = 0x0, offset = 0x0, length = 0x4c}
data_p => data
call acc_copyin(data_p) ! h=0xb191b0, s=76
! NEW
! (gdb) print tgt
! $7 = (struct target_mem_desc *) 0xa7abc0
! (gdb) print/x *tgt
! $8 = {refcount = 0x1, array = 0xc21cd0, tgt_start = 0x7fffcf000200,
tgt_end = 0x7fffcf00024c, to_free = 0x7fffcf000200, prev = 0x0, list_count =
0x1, device_descr = 0x80bae0, list = 0xa7ac00}
! (gdb) print/x tgt->list[0]
! $9 = {key = 0xc21cd0, copy_from = 0x0, always_copy_from = 0x0,
do_detach = 0x0, offset = 0x0, length = 0x4c}
! That means, this creates a new mapping, 'acc_copyin(data_p)' does *not*
dereference 'data_p => data'. So far, so good? But:
print *, acc_is_present(data_p) ! h=0xb18db0, s=76
! Not mapped; this neither looks up the 'acc_create(data)', nor the
'acc_copyin(data_p)'.
!$acc enter data copyin(data_p)
! 0 ("to" '*data_p.data')
! (gdb) print n
! $12 = (splay_tree_prefix_splay_tree_key) 0xb19480
! OLD 'data' -- expected
! '++dynamic_refcount'
! 1 ("pset" 'data_p'), 2 ("pointer assign" 'data_p.data')
! NEW
! Was somewhat expecting this would look up what 'acc_copyin(data_p)'
mapped?
! (gdb) print tgt
! $4 = (struct target_mem_desc *) 0xc38000
! (gdb) print/x *tgt
! $5 = {refcount = 0x1, array = 0xc38770, tgt_start = 0x7fffcf000400,
tgt_end = 0x7fffcf000440, to_free = 0x7fffcf000400, prev = 0x0, list_count =
0x2, device_descr = 0x80bae0, list = 0xc38040}
! (gdb) print/x tgt->list[0]
! $6 = {key = 0xc38770, copy_from = 0x0, always_copy_from = 0x0,
do_detach = 0x0, offset = 0x0, length = 0x40}
! (gdb) print/x tgt->list[1]
! $7 = {key = 0xc38770, copy_from = 0x0, always_copy_from = 0x0,
do_detach = 0x0, offset = 0x0, length = 0x0}
print *, acc_is_present(data_p) ! h=0xb18db0, s=76
! Same as above; still isn't mapped.
!$acc serial present(data_p)
! 0 ("force_present" '*data_p.data')
! (gdb) print n
! $14 = (splay_tree_prefix_splay_tree_key) 0xb19480
! OLD 'data' -- expected
! 1 ("pset" 'data_p'), 2 ("pointer assign" 'data_p.data')
! (gdb) print n
! $10 = (splay_tree_prefix_splay_tree_key) 0xc38770
! OLD "pset" 'data_p' (from 'enter data copyin(data_p)') -- expected
data_p(5) = 55
!$acc end serial
end program main
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug fortran/96080] OpenACC/Fortran runtime library routines vs. Fortran 'pointer'
2020-07-06 15:13 [Bug fortran/96080] New: [OpenACC] 'acc_is_present' for Fortran 'pointer' tschwinge at gcc dot gnu.org
2020-07-09 19:30 ` [Bug fortran/96080] OpenACC/Fortran runtime library routines vs. " tschwinge at gcc dot gnu.org
@ 2020-07-09 20:00 ` tschwinge at gcc dot gnu.org
2021-07-01 10:15 ` tschwinge at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: tschwinge at gcc dot gnu.org @ 2020-07-09 20:00 UTC (permalink / raw)
To: gcc-bugs
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?).
^ permalink raw reply [flat|nested] 4+ messages in thread