on 2023/5/30 17:26, juzhe.zh...@rivai.ai wrote: > Ok. > > It seems that for this conditions: > > + /* If we're vectorizing a loop that uses length "controls" and > + can iterate more than once, we apply decrementing IV approach > + in loop control. */ > + if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) > + && !LOOP_VINFO_LENS (loop_vinfo).is_empty () > + && LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo) == 0 > + && !(LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo) > + && known_le (LOOP_VINFO_INT_NITERS (loop_vinfo), > + LOOP_VINFO_VECT_FACTOR (loop_vinfo)))) > + LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo) = true; > > > I should add direct_supportted_p (SELECT_VL...) to this is that right?
I guess no, with this condition any targets without SELECT_VL are unable to leverage the new decrement scheme for lengths, as your reply in PR109971 you didn't meant to disable it. IIUC, what Richi suggested is to introduce one new IV just like the previous one which has non-variable step, then it's SCEV-ed and some analysis based on it can do a good job. Since this is mainly for targets without SELECT_VL capability, I can follow up this if you don't mind. BR, Kewen
