https://gcc.gnu.org/bugzilla/show_bug.cgi?id=27504
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #3) > Confirmed again. > So looking at the IR, it took until PHI-OPT4 to be able to convert it into: > <bb 2> [local count: 1073741824]: > if (x_3(D) != 0) > goto <bb 3>; [50.00%] > else > goto <bb 4>; [50.00%] > > <bb 3> [local count: 536870913]: > _1 = x_3(D) & 85; > _5 = _1 != 0; > _6 = (int) _5; > > <bb 4> [local count: 1073741824]: > # iftmp.0_2 = PHI <_6(3), 0(2)> In GCC 12+, phiopt2 is able to convert that into the above. One thing that could be tried is to replace x_3 with 0 and see if _6 would simplify down to 0 (other the phi argument). This could be part of phiopt but would need a lot of work really. Note VRP is able to handle the other way around already: that is: `(x & 0x55) && x ` But that is simplier.
