Horton

Re: add AVX2 support to simd.h

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: John Naylor <johncnaylorls@gmail.com>, Ants Aasma <ants@cybertec.at>, pgsql-hackers@postgresql.org
Date: 2024-01-02T22:00:18Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Improve style of pg_lfind32().

  2. Fix compiler warning for pg_lfind32().

  3. Micro-optimize pg_lfind32().

  4. Introduce helper SIMD functions for small byte arrays

  5. Optimize xid/subxid searches in XidInMVCCSnapshot().

On Tue, Jan 02, 2024 at 12:50:04PM -0500, Tom Lane wrote:
> The patch needs better comments (as in, more than "none whatsoever").

Yes, will do.

> Also, do you really want to structure the header so that USE_SSE2
> doesn't get defined?  In that case you are committing to provide
> an AVX2 replacement every single place that there's USE_SSE2, which
> doesn't seem like a great thing to require.  OTOH, maybe there's
> no choice given than we need a different definition for Vector8 and
> Vector32?

Yeah, the precedent is to use these abstracted types elsewhere so that any
SIMD-related improvements aren't limited to one architecture.  There are a
couple of places that do explicitly check for USE_NO_SIMD, though.  Maybe
there's an eventual use-case for using SSE2 intrinsics even when you have
AVX2 support, but for now, ensuring we have an AVX2 replacement for
everything doesn't seem particularly burdensome.

-- 
Nathan Bossart
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