AVX is great until the moment you want to slide every element in a vector one space to the left

[joshjers@mastodon.gamedev.place]

AVX is great until the moment you want to slide every element in a vector one space to the left

it's *possible* but it's a pain in the ass

(less so in AVX2, but still)

[tomf@mastodon.gamedev.place]

@JoshJers There aren't that many CPUs with AVX but not AVX2 - maybe you can just skip them? Of course what you really want is AVX512 and beyond...

[joshjers@mastodon.gamedev.place]

@TomF alas, my own PC doesn't have 512, so I miss out on all the *super* cool instructions 😫

[tomf@mastodon.gamedev.place]

@JoshJers I know man, I know :-(

[joshjers@mastodon.gamedev.place]

@TomF haha oh is it still that rare? I just assumed that my 2009-ass CPU was the problem

[joshjers@mastodon.gamedev.place]

@TomF er, 2017

I was *wildly* off hah

[tomf@mastodon.gamedev.place]

@JoshJers Yeah they kept dicking around and putting 512 in, taking it out, shaking it all around. At one point they were talking about everything having "AVX256" which is AVX512 instructions, but only half-width. It's not *quite* as goofy as it sounds. I think they have now decided not to do that? But yeah it's taking ages.

[joshjers@mastodon.gamedev.place]

@TomF not to mention the explosion of AVX 512 flavors that make it *really easy* to understand wtf is even going on

[dotstdy@mastodon.social]

@JoshJers @TomF thankfully there's an easy answer for good avx512 support now - buy amd. :')

[tomf@mastodon.gamedev.place]

@dotstdy @JoshJers Yeah, the not-so-secret backup plan worked surprisingly well.