https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127702
Bug ID: 127702
Summary: The result of NUM_IMAGES depends on the number of
failed or stopped images
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: mikael at gcc dot gnu.org
Target Milestone: ---
Testcase:
program prog
use, intrinsic :: iso_fortran_env, only: stat_stopped_image
implicit none
if (num_images() < 2) stop
print *, this_image(), num_images()
sync all
if (this_image() == 1) then
stop
else
do while (image_status(1) /= stat_stopped_image)
end do
end if
print *, this_image(), num_images()
end program
When run with shmem caf library, it shows an output similar to this:
8 8
5 8
3 8
1 8
4 8
7 8
2 8
6 8
STOP
6 7
7 7
4 7
8 7
3 7
5 7
2 7
I expect the second column to have the same value all along. A similar result
is obtained with failed images instead of stopped images.
F2023 (5.3.4 Program execution) contains:
> Execution of a program consists of the asynchronous execution of a fixed
> number (which may be one) of its images.
(16.9.156 NUM_IMAGES):
> Result Value. The number of images in the specified team, or in the current
> team if no team is specified.
So it's not indicated that the number may change because of a change of
execution state of an image. And it also makes more sense to have a fixed
value, because it may be used as loop bound to query the execution state of all
the other images; having a decreasing number would mean that the execution
state would no longer be queried for some of the images.
