runtime: PoC: generate call to LLVM intrinsic instead of calling runtime functions when possible; handling NINT for a beginning

[pawosm-arm]

[sscalpone]

The overall flow of this pull request is like this:

If(op == IL_NINT) { op = “_mth_i_nint”; } …. If(op == “_mth_i_nint”) { op == llvm.intrinsic.cvt; }

My preference is to skip the intermediate conversion to _mth_i_nint.

If(op == IL_NINT) { op = llvm.intrinsic.cvt }

Advantages to skipping the intermediate conversion: Availability of IL_NINT for folding Code is less complex; does not use strcmp and magic routine name

Assuming we want to map as many flang ILIs directly to llvm intrinsics, it would be nice to have a good model in place.

[bryanpkc]

Closing stale PR.