| > "AVX512 instructions are now supported on X86-64" This is the first news I've seen on HN in weeks that I am genuinely excited about! I have several AVX-2 hobby projects in Common Lisp, and an AVX-512 machine. It's an unexpected surprise to read this morning that this very useful ISA is suddenly unlocked. I'll be trying it out right away. (edit: Looks like they mean *compiler* support for AVX-512, but not SB-SIMD definitions (yet). So I believe the only way for end-users to call AVX-512 instructions right now is to write custom VOP's). > "Or are these intrinsics you have to explicitly ask for?" There are language SIMD types and you explicitly use SIMD functions that operate on them. I believe it's essentially the same idea as C intrinsics. You can for example write (interactively) (u32.8+ (make-u32.8 0 1 2 3 4 5 6 7)
(u32.8 10))
;; => #<SB-EXT:SIMD-PACK-256 10 11 12 13 14 15 16 17>
And that's VPADDD under the hood. Or reading an array (loop with sum = (f32.8 0.0f0)
for index below (* 8 (floor length 8)) by 8
do (setq sum (f32.8+ (f32.8-aref array index)
sum))
finally (return sum))
which compiles down to a small loop around the vector insts VMOVUPS YMM1, [RDX+RCX*2+1]
VADDPS YMM0, YMM1, YMM0
I much prefer it to writing intrinsics in C (and the results are just as good). It's an interactive, exploratory, coding: I write small modular functions, SBCL compiles them on the fly, I glue them together with high-level language constructs. |
Nice to hear! :)
It is the basic compiler support, and lots of instructions added. However, you can't use knor, knoq and similar since they require scheduling of k-masks. Not done yet. But you can certainly use some of avx512 instructions and add yourself if you need some that is not available already. Check https://github.com/sbcl/sbcl/blob/master/src/compiler/x86-64....