https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81805
--- Comment #3 from Alexander Monakov <amonakov at gcc dot gnu.org> --- The new testcase fails on any target and not related to offloading. Simplified further: #define N 32ULL int a[N]; const unsigned long long c = 0x7fffffffffffffffULL; f2_tpf_static32 (void) { unsigned long long i; #pragma omp for for (i = c + N; i > c; i -= 1ULL) a[i - 1ULL - c] -= 4; } in the .original dump we have: { long long unsigned int i; long long unsigned int i; #pragma omp for for (i = 9223372036854775839; i < 0; i = i + 18446744073709551615) { a[i + 9223372036854775808] = a[i + 9223372036854775808] + -4 } } and soon after we deduce that loop doesn't iterate because i is unsigned. The comparison should have read '(long long)i < 0', no idea how the cast is lost.