On Monday, 11 June 2018 at 03:34:59 UTC, Basile B. wrote:
- default linux:
https://github.com/gcc-mirror/gcc/blob/master/libgcc/memcpy.c
To see what is executed when you call memcpy() on a regular
GNU/Linux distro, you'd want to have a look at glibc instead. For
example, the AVX2 and AVX512 implementations are in
sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S
and
sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S,
as forwarded to by memmove-avx2-unaligned-erms.S and
memmove-avx512-unaligned-erms.S.
(Pop quiz: Why might a separate "no-vzeroupper" variant be a good
idea?)
— David
