https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112758
--- Comment #7 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > I must say I have no idea what WORD_REGISTER_OPERATION says about the upper > bits of a paradoxical SUBREG if it is a MEM and load_extend_op (inner_mode) > is ZERO_EXTEND (zeros then? Yes. > Then this optimization is ok), or something else? And what it says on REGs. That it contains the result of the operation that was applied to the SUBREG as if it was applied to the entire REG, provided that word_register_operation_p is true. Otherwise, it's undefined.
