Inplement aarch64 neon instructions in AdvSIMD(shift). About 24 shift instructions:
      sshr,ushr,ssra,usra,srshr,urshr,srsra,ursra,sri,shl,sli,sqshlu,sqshl,uqshl,shrn,sqrshr$
 and 4 convert instructions:
      scvtf,ucvtf,fcvtzs,fcvtzu