[Bug middle-end/78266] broken openacc loop partitioning on nvptx offloading targets

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78266

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
F.i., we generate:
...
  _41 = GOACC_DIM_SIZE (0);
  _29 = (signed char) _41;
...
where _41 is 256.

When folding in forwprop2, we fold _29 to '0':
...
gimple_simplified to _29 = 0;
...