Re: add AVX2 support to simd.h

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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