PPC64 libmvec implementation of sincos

[GT <tnggil at protonmail dot com>]

I am attempting to create a vector version of sincos for PPC64.
The relevant discussion thread is on the GLIBC libc-alpha mailing list.
Navigate it beginning at https://sourceware.org/ml/libc-alpha/2019-09/msg00334.html

The intention is to reuse as much as possible from the existing GCC implementation of other libmvec functions.
My questions are: Which function(s) in GCC;

1. Gather scalar function input arguments, from multiple loop iterations, into a single vector input argument for the vector function version?
2. Distribute scalar function outputs, to appropriate loop iteration result, from the single vector function output result?

I am referring especially to vectorization of sin and cos.

Thanks.
Bert Tenjy.