https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103750
--- Comment #1 from Hongtao.liu <crazylht at gmail dot com> ---
kmovw here is zero_extend, and at gimple level it's not redundant in loop.
_31 = MEM[(const __m256i_u * {ref-all})n_5];
_30 = MEM[(const __m256i_u * {ref-all})n_5 + 32B];
_28 = VIEW_CONVERT_EXPR<__v16hi>(_31);
_29 = __builtin_ia32_ucmpw256_mask (_28, _20, 0, 65535);
_26 = VIEW_CONVERT_EXPR<__v16hi>(_30);
_27 = __builtin_ia32_ucmpw256_mask (_26, _20, 0, 65535);
_2 = (int) _27;
_3 = (int) _29;
_15 = __builtin_ia32_kortestzhi (_3, _2);
_25 = (unsigned char) _15;
if (_25 != 0)
but at rtl level, _28/_29 propagate into kortest and be partial redundant but
failed to sink or be eliminated.
(insn 29 27 30 3 (set (reg:SI 83 [ _2 ])
(zero_extend:SI (reg:HI 111))) "test.c":24:32 147 {*zero_extendhisi2}
(nil))
(insn 30 29 31 3 (set (reg:SI 116 [ _29 ])
(zero_extend:SI (reg:HI 106))) "test.c":24:32 147 {*zero_extendhisi2}
(nil))
(insn 58 56 60 8 (parallel [
(set (reg:HI 120)
(unspec:HI [
(subreg:HI (reg:SI 83 [ _2 ]) 0)
] UNSPEC_TZCNT))
(clobber (reg:CC 17 flags))
(insn 52 51 55 7 (parallel [
(set (reg/v:SI 88 [ idx ])
(ctz:SI (reg:SI 116 [ _29 ])))
(clobber (reg:CC 17 flags))
