On Tue, 7 Dec 2021, Richard Sandiford wrote: > Richard Biener <rguent...@suse.de> writes: > > On Tue, 7 Dec 2021, Andre Vieira (lists) wrote: > > > >> Hi, > >> > >> Rebased on top of the epilogue mode patch. > >> > >> OK for trunk? > > > > @@ -7242,7 +7315,8 @@ vectorizable_reduction (loop_vec_info loop_vinfo, > > participating. */ > > if (ncopies > 1 > > && (STMT_VINFO_RELEVANT (stmt_info) <= vect_used_only_live) > > - && reduc_chain_length == 1) > > + && reduc_chain_length == 1 > > + && loop_vinfo->suggested_unroll_factor == 1) > > single_defuse_cycle = true; > > > > if (single_defuse_cycle || lane_reduc_code_p) > > > > It seems to me that 'ncopies' should include > > loop_vinfo->suggested_unroll_factor already so the check shouldn't be > > necessary. > > Yeah, ncopies will be >1 for the unroll case. But the point is that > for unrolling, we want each unrolled loop to have its own reduction > accumulator, since reducing the aggregate loop-carried latency is one > of the main benefits of unrolling a reduction.
Ah, I see. Please add a comment above this check then. Richard.
