Add TD pattern for REV16Xr

Author: adprasad-nvidia

llvm/lib/Target/AArch64/AArch64InstrInfo.td

@@ -2843,6 +2843,7 @@ def : Pat<(srl (bswap top16Zero:$Rn), (i64 16)), (REV16Wr GPR32:$Rn)>;
 def : Pat<(srl (bswap top32Zero:$Rn), (i64 32)), (REV32Xr GPR64:$Rn)>;
 
 def : Pat<(AArch64rev16_scalar GPR32:$Rn), (REV16Wr GPR32:$Rn)>;
+def : Pat<(AArch64rev16_scalar GPR64:$Rn), (REV16Xr GPR64:$Rn)>;
 
 def : Pat<(or (and (srl GPR64:$Rn, (i64 8)), (i64 0x00ff00ff00ff00ff)),
               (and (shl GPR64:$Rn, (i64 8)), (i64 0xff00ff00ff00ff00))),