[Bug libgomp/81805] Another libgomp.c/for-5.c failure on nvptx -- illegal memory access

["amonakov at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

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.