https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103771
--- Comment #22 from Hongtao.liu <crazylht at gmail dot com> --- (In reply to Hongtao.liu from comment #21) > (In reply to Hongtao.liu from comment #20) > > (In reply to Richard Biener from comment #19) > > > Ah, so the issue is missing -mavx512bw which means we end up with a AVX2 > > > style > > > mask for V32QImode. With -mavx512bw the code vectorizes fine. > > > > Vectorization code is worse than before, now we need to pack vectorized mask > > which takes extra 3 instructions. > > Current ifcvt convert > > ---------dump of .ch_vect------- > if (x.1_14 > 255) > goto <bb 4>; [50.00%] > else > goto <bb 5>; [50.00%] > > <bb 4> [local count: 477815112]: > _17 = -_5; > _18 = _17 >> 31; > iftmp.0_19 = (unsigned char) _18; > goto <bb 6>; [100.00%] > > <bb 5> [local count: 477815112]: > iftmp.0_20 = (unsigned char) _5; > > <bb 6> [local count: 955630225]: > # iftmp.0_21 = PHI <iftmp.0_19(4), iftmp.0_20(5)> > -------dump end--------- > > > to > ---- dump of .ifcvt--------- > _41 = -x.1_14; > _17 = (int) _41; > _18 = _17 >> 31; > iftmp.0_19 = (unsigned char) _18; -- vec_pack_trunc > iftmp.0_20 = (unsigned char) _5; -- vec_pack_trunc > iftmp.0_21 = x.1_14 > 255 ? iftmp.0_19 : iftmp.0_20; -- vec_pack_trunc > *_6 = iftmp.0_21; > x_16 = x_24 + 1; > -----dump end---------- > > > if ifcvt output things like > ------------optimal .ifcvt------ > _41 = -x.1_14; > _17 = (int) _41; > _18 = _17 >> 31; > iftmp.0_21 = x.1_14 > 255 ? _18 : _5; > iftmp.0_22 = (unsigned char) iftmp.0_21; --- vec_pack_trunc > *_6 = iftmp.0_22; > x_16 = x_24 + 1; > ------------end------------ > > we can save operations for packing mask(3 vec_pack_trunc vs 1 > vec_pack_trunc?). Or maybe a gimple simplification for it?
