I tried compiling a file with "-mllvm -debug", and found that this caused a crash, since there was an unimplemented function in SystemZAsmParser.
I have tried to implement this to make a readable output which basically means trying to print the values of the operands by casting them to the right MCExpr subclass.
I tried to print register names but did not find a trivial way to get the MachineRegisterInfo. Now register integer values are printed instead.
Index should also be printed *before* the base.