https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82062
--- Comment #10 from rguenther at suse dot de <rguenther at suse dot de> --- On Wed, 25 Oct 2017, ebotcazou at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82062 > > --- Comment #9 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > > There are two things to it, stripping sign-nops from the comparison > > operand (careful!) and stripping arbitrary nops from the result > > to look for an argument equal to the comparison operand. > > My change doesn't add any stripping, it only does: > > if (TREE_CODE (arg1) == NOP_EXPR > && operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0)) > return true; > > on the unstripped operands, i.e. it only adds back a simplified version of the > second test removed by Marek's change; it's independent of the first test. Simplified but not equal - you are also stripping a possible truncation. I think the original code only ever stripped widening conversions. It also had some additional constraints on the stripping looking at the other comparison operand (for some weird reason...). I guess I'm ok with your proposed change if you restrict it to widening conversions (and use CONVERT_EXPR_P (arg1)).
