Add definitely_not_01 set to ShapeEnv. (#89871)
This set tracks symbols which we know are definitely not 0/1, and thus
can be further simplified when we try to work out their static value
without guards. Right now, all allocated symbols are in this set,
but we will later add symbols which don't uphold this.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/89871
Approved by: https://github.com/albanD
