https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87361
--- Comment #6 from Segher Boessenkool <segher at gcc dot gnu.org> --- I think nonzero_bits should use SUBREG_PROMOTED_VAR_P and SUBREG_PROMOTED_UNSIGNED_P for REGs, not LOAD_EXTEND_OP, which is only for MEMs.
