[PATCH 1v2/3][vect] Add main vectorized loop unrolling
Andre Vieira (lists)
Tue Nov 30 11:36:54 GMT 2021
On 25/11/2021 12:46, Richard Biener wrote:
> Oops, my fault, yes, it does. I would suggest to refactor things so
> that the mode_i = first_loop_i case is there only once. I also wonder
> if all the argument about starting at 0 doesn't apply to the
> not unrolled LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P as well? So
> what's the reason to differ here? So in the end I'd just change
> the existing
> if (LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P (first_loop_vinfo))
> if (LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P (first_loop_vinfo)
> || first_loop_vinfo->suggested_unroll_factor > 1)
> and maybe revisit this when we have an actual testcase showing that
> doing sth else has a positive effect?
So I had a quick chat with Richard Sandiford and he is suggesting
resetting mode_i to 0 for all cases.
He pointed out that for some tunings the SVE mode might come after the
NEON mode, which means that even for not-unrolled loop_vinfos we could
end up with a suboptimal choice of mode for the epilogue. I.e. it could
be that we pick V16QI for main vectorization, but that's VNx16QI + 1 in
the array, so we'd not try VNx16QI for the epilogue.
This would simplify the mode selecting cases, by just simply restarting
at mode_i in all epilogue cases. Is that something you'd be OK?
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