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From: Richard Sandiford <richard.sandiford@arm.com>
To: Richard Biener <rguenther@suse.de>
Cc: gcc-patches@gcc.gnu.org,  ams@codesourcery.com,  juzhe.zhong@rivai.ai
Subject: Re: [PATCH][RFT] Vectorization of first-order recurrences
Date: Wed, 12 Oct 2022 10:48:27 +0100	[thread overview]
Message-ID: <mptwn95e5jo.fsf@arm.com> (raw)
In-Reply-To: <20221010110339.E9E2513479@imap2.suse-dmz.suse.de> (Richard Biener's message of "Mon, 10 Oct 2022 13:03:39 +0200 (CEST)")

Richard Biener <rguenther@suse.de> writes:
> +  /* First-order recurrence autovectorization needs to handle permutation
> +     with indices = [nunits-1, nunits, nunits+1, ...].  */
> +  vec_perm_builder sel (nunits, 1, 3);
> +  for (int i = 0; i < 3; ++i)
> +    sel.quick_push (nunits - dist + i);
> +  vec_perm_indices indices (sel, 1, nunits * 2);

Should be:

  vec_perm_indices indices (sel, 2, nunits);

With that change, the patch passes testing on SVE.  vect-recurr-6.c
fails to vectorise, but I think that's because SVE doesn't yet support
the required permute.

Thanks,
Richard

      parent reply	other threads:[~2022-10-12  9:48 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-10 11:03 Richard Biener
2022-10-10 11:13 ` juzhe.zhong
2022-10-10 13:57 ` Andrew Stubbs
2022-10-10 14:08   ` 钟居哲
2022-10-11  7:01   ` Richard Biener
2022-10-11  8:42     ` Richard Sandiford
2022-10-14  7:07       ` Richard Biener
2022-10-14  7:20         ` juzhe.zhong
2022-10-14  9:42         ` Andrew Stubbs
2022-10-14  9:46           ` Richard Biener
2022-10-17  8:48         ` Richard Sandiford
2022-10-11  8:34 ` juzhe.zhong
2022-10-17 12:14   ` Richard Biener
2022-10-12  9:48 ` Richard Sandiford [this message]

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