https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119904
Bug ID: 119904
Summary: [OpenMP] wrong code as map item sorting does not work
- fails with: libgomp: Pointer target of array section
wasn't mapped
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Keywords: openmp, wrong-code
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
Target Milestone: ---
I think this might be related to some existing bug like PR113867 and/or
PR113724 - especially as the there is sorting done in
omp_gather_mapping_groups_1
The problem is that the following mapping FAILS
map(test_lst) map(tofrom: test_lst[0][:1])
while this mapping WORKS:
map(tofrom: test_lst[0][:1]) map(test_lst)
The problem is that 'map(test_lst)' has to be mapped first, i.e. it needs
to be ordered such that the mapping happens first. As GCC evaluates clauses
from right to left, the second one works.
As mentioned, some clause ordering happens already – but obviously not in this
case.
-----------------------
int main ()
{
int *array[512], *array2[512];
for (int i = 0; i < 512; i++)
{
array[i] = (int*) __builtin_malloc (sizeof (int));
array2[i] = (int*) __builtin_malloc (sizeof (int));
array[i][0] = 1;
array2[i][0] = -1;
}
// FAILS: libgomp: Pointer target of array section wasn't mapped
#pragma omp target map(array) map(tofrom: array[0][:1])
for (int i = 0; i < 512; i++)
array[i][0] = 2;
// WORKS
#pragma omp target map(tofrom: array2[0][:1]) map(array2)
for (int i = 0; i < 512; i++)
array2[i][0] = -2;
int sum = 0;
int sum2 = 0;
for (int i = 0; i < 512; i++)
{
sum += array[i][0];
sum2 += array2[i][0];
__builtin_free (array[i]);
__builtin_free (array2[i]);
}
if (sum != 2*512 || sum2 != -2*512)
__builtin_abort ();
return 0;
}
-----------------------
A fancier version would use:
int **array = (int**) malloc(sizeof(int*)*512);
which requires mapping 'array[:512]' and attaching it to 'array'
