ARMv8.2-A introduces half-precision floating point data processing. This patch adds the fp16 scalar intrinsics for this architecture as described in the ARM ACLE document. Only the front-end intrinsic work is done here. Some backend work related to instruction selection still needs to be done.
This work is a continuation of https://reviews.llvm.org/D32511 which addressed ARMv8.2-A vector intrinsics.