AVX2

[p0nce]

179 TODO
159 TODO
142 TODO
132 TODO
112 TODO
100 TODO
87 TODO
76 TODO

[p0nce]

AVX super annoying to do since efficiently doing the instructions without 256-bit vectors is involved

[p0nce]

Even when AVX is disabled, if all intrinsics are implement with proper splitting when needed, you can speed up with AVX "intrinsics". Of course, doesn't work everytime but often enough to speed things up in general.

Let's measure time to make 81920000 atan2 operations.

With -mattr=+avx2 (AVX enabled)

- Naive (std.complex.arg):       1581.3 ms
- Written with AVX intrinsics:     61.5 ms
- Written with SSE intrinsics:    103.6 ms


Without -mattr=+avx2 (AVX disabled)

- Naive (std.complex.arg):       1499.6 ms
- Written with AVX intrinsics:    102.9 ms
- Written with SSE intrinsics:    119.9 ms

(EDIT: though, it's not systematic either, if SSE intrinsics don't win over D code often the AVX semantics also don't win)