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[Bug target/80846] auto-vectorized AVX2 horizontal sum should narrow to 128b right away, to be more efficient for Ryzen and Intel
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 07 Sep 2017 11:53:47 +0000
- Subject: [Bug target/80846] auto-vectorized AVX2 horizontal sum should narrow to 128b right away, to be more efficient for Ryzen and Intel
- Auto-submitted: auto-generated
- References: <bug-80846-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80846
--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #11)
> that's not using the unpacking strategy (sum adjacent elements) but still the
> vector shift approach (add upper/lower halves). That's sth that can be
> changed independently.
>
> Waiting for final vec_extract/init2 optab settling.
That should be settled now.
BTW, for reductions in PR80324 I've added for avx512fintrin.h __MM512_REDUCE_OP
which for reductions from 512-bit vectors uses smaller and smaller vectors,
perhaps that is something we should use for the reductions emitted by the
vectorizer too (perhaps through a target hook that would emit gimple for the
reduction)?