The trouble as in ARMAsmParser, in ParseInstruction method. It assumes that ARM::R12 + 1 == ARM::SP.
It is wrong, since ARM::<Register> codes are generated by tablegen and actually could be any random numbers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205524 91177308-0d34-0410-b5e6-96231b3b80d8