There may be something I am overlooking here, but I really don't think we need to or want to change the back end. Just add the new builtins to the front end as aliases to the existing ones and generate the same code from the front end.
Also, we will want this backported to 12.0.1. Please open a bugzilla bug that we can mark as blocking the release and add a link to that PR in this review.
The _mma_ version of the builtin is supposed to just be an alias for the _vsx_ version. There is no need to add a new intrinsic and produce it here. Just produce the same intrinsic for both builtins.
|1139 ↗||(On Diff #337765)|
Please don't define these unless we absolutely need them.
If we don't add these, I think all the code in the back end is no longer needed.