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devel / comp.lang.c++ / clang copies with AVX-512

clang copies with AVX-512

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https://www.novabbs.com/devel/article-flat.php?id=148&group=comp.lang.c%2B%2B#148

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From: Bonita.M...@gmail.com (Bonita Montero)
Newsgroups: comp.lang.c++
Subject: clang copies with AVX-512
Date: Wed, 17 May 2023 08:14:36 +0200
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by: Bonita Montero - Wed, 17 May 2023 06:14 UTC

My new Windows PC, a Ryzen 9 7950X, has some sort of AVX-512.
I thought I'll look if Visual C++ copies data structures occupying
a whole 64 byte block with AVX-512 moves. It didn't but it used
AVX with four moves. But clang-cl, the mostly MSVC-compatible
clang++-variant, uses AVX-512:

__declspec(noinline)
void fn( t512 const &src, t512 &dst )
{ dst = src;
}

"?fn@@YAXAEBV?$array@D$0EA@@std@@AEAV12@@Z": #
@"?fn@@YAXAEBV?$array@D$0EA@@std@@AEAV12@@Z"
# %bb.0:
vmovups zmm0, zmmword ptr [rcx]
vmovups zmmword ptr [rdx], zmm0
vzeroupper
ret

Subject	Author
clang copies with AVX-512	Bonita Montero