This patch implements the SVFS implementation according to RFC. Builds on top of Vector Function ABI name demangling patch. [https://reviews.llvm.org/D66024].
RFC: Interface user provided vector functions with the vectorizer.
[http://lists.llvm.org/pipermail/llvm-dev/2019-June/133484.html]
This patch also contains changes as suggested in the previous review. This new patch has been broken down from the earlier patch as suggested.
[https://reviews.llvm.org/D64095]