https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104356
--- Comment #35 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I meant something like:
with System.Unsigned_Types; use System.Unsigned_Types;
function F (X, Y : Unsigned) return Unsigned is
Z : Unsigned;
begin
if X >=2 then
return 0;
end if;
Z := Y;
if X = 1 then
Z := Y + 4;
end if;
return Z / X;
end;
and there evrp does with -O2 -gnatp optimize away the division.
Though that is likely the X / boolean_range_Y case which you've disabled.
In any case, I think you want to hear from Andrew/Aldy where exactly does
VRP/ranger assume UB on integer division by zero.
