The tLDR instruction wasn't encoded properly:

<MCInst 2251 <MCOperand Reg:70> <MCOperand Reg:66> <MCOperand Imm:0> <MCOperand Reg:0> <MCOperand Imm:14> <MCOperand Reg:0>>

Notice that the "reg" here is 0, which is an invalid register. Put a check in
the code for this to prevent crashing.

llvm-svn: 120766