In JDK-8248188, IntrinsicCandidate and API is added for Base64 decoding and implements the intrinsic for Power64LE.

We can do the same thing for aarch64 with ld4/tbl/tbx/st3 NEON instructions, a basic idea can be found at http://0x80.pl/articles/base64-simd-neon.html#encoding-quadwords.