Not sure why the article links to some runtimejs copy of musl [1]. It's quite old (2014 vintage) to the point where the referenced code is no longer present upstream [2].

[1] https://github.com/runtimejs/musl-libc/blob/master/crt/x86_6...

[2] https://git.musl-libc.org/cgit/musl/commit/?id=6fef8cafbd0f6...