There were a few minor issues with the two routines, partially because of
not handling corner cases and partially some clarifications are only in
newer versions of the spec.
In particular, for omp_target_is_present
* NULL pointer aren't regarded as present
* For (unified-)shared memory, claiming that something has always corresponding
storage is wrong - it mostly never has. (but it is omp_target_is_accessible).
* Even with shared memory, 'declare target' usually has device memory. For
'link' it is made to point to the host, i.e. it is not mapped, all others
are still mapped. (With 'requires self_mapping', 'enter' should also not be
mapped (and turned internally to 'link'), only 'local' needs to be mapped.)
For omp_get_mapped_ptr
* For NULL we can return NULL early also for devices.
* For shared memory, we shouldn't touch link (it is not counting as mapped);
hence return NULL for it.
The documentation was updated add some missing cross references as the more
useful ones were missing. Additionally, the description for the two modified
routines has been updated.
libgomp/ChangeLog:
* target.c (omp_target_is_present, omp_get_mapped_ptr): Update handling
for nullptr and shared-memory devices.
* libgomp.texi (omp_target_is_present, omp_get_mapped_ptr): Update
description, add see-also @refs.
(omp_target_is_accessible, omp_target_associate_ptr): Add see-also
@refs.
* testsuite/libgomp.c/omp_target_is_present.c: New test.
* testsuite/libgomp.c/omp_target_is_present-2.c: New test.
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