[PATCH] [AArch64]Implement 128 bit register copy with NEON.

[Tim Northover]

  Hi Kevin,

  This is definitely a good idea (the existing "solution" was an
  appalling hack), but I think the instructions chosen are sub-optimal.
  ARM has designated the instruction "ORR vD.16b, vN.16b, vN.16b" as the
  official 128-bit move instruction.

  CPU designers are likely to optimise around this (for example it might
  not even make it to the ALU, and be handled directly by the register
  renaming hardware) so that's what LLVM should be generating, I think.

  Cheers.

  Tim.

http://llvm-reviews.chandlerc.com/D2264