Problem about "llc -march=msil"

It probably means that the MSIL backend hasn’t been updated with (or never had) support for an intrinsic function used in your LLVM module. The printed Intrinsic ID identifies the intrinsic, but if you set a breakpoint on that line in llc, you should also be able to find its name by evaluating an expression like F->getNameStart() in your debugger.