[ruby-core:96760] [Ruby master Misc#16487] Potential for SIMD usage in ruby-core

Issue #16487 has been updated by ahorek (Pavel Rosick=FD).


> Could you extend on that ? I'm not sure I understand what you mean here.

for maximum portability, you should use `-march=3Dx86-64`

in this case, even if your current CPU supports AVX, the compiler can't use=
 AVX instructions for a regular code
https://godbolt.org/z/YSNeQB
loading a few hand-crafted functions dynamically at runtime in order to ove=
rcome this limitation seems too hacky...


@sam.saffron - a separate gem would be probably the best choice

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Misc #16487: Potential for SIMD usage in ruby-core
https://bugs.ruby-lang.org/issues/16487#change-83752

* Author: byroot (Jean Boussier)
* Status: Open
* Priority: Normal
* Assignee: =

----------------------------------------
### Context

There are several ruby core methods that could be optimized with the use of=
 SIMD instructions.

I experimented a bit on `coderange_scan` https://github.com/Shopify/ruby/pu=
ll/2, and Pavel Rosick=FD experimented on `String#strip` https://github.com=
/ruby/ruby/pull/2815.

### Problem

The downside of SIMD instructions is that they are not universally availabl=
e.
So it means maintaining several versions of the same code, and switching th=
em either statically or dynamically.

And since most Ruby users use precompiled binaries from repositories and su=
ch, it would need to be dynamic if we want most users to benefit from it.

So it's not exactly "free speed", as it means a complexified codebase.

### Question

So the question is to know wether ruby-core is open to patches using SIMD i=
nstructions ? And if so under which conditions.

cc @shyouhei





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