Override runOnMachineFunction for X86ISelDAGToDAG so that we can
reset the subtarget on each function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209384 91177308-0d34-0410-b5e6-96231b3b80d8
Override runOnMachineFunction for ARMISelDAGToDAG so that we can
reset the subtarget on each function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209386 91177308-0d34-0410-b5e6-96231b3b80d8
MC: formalise some assertions into proper errors

Now that clang can be used as an assembler via the IAS, invalid assembler inputs
would cause the assertions to trigger.  Although we cannot recover from the
errors here, nor provide caret diagnostics, attempt to handle them slightly more
gracefully by reporting a fatal error.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209387 91177308-0d34-0410-b5e6-96231b3b80d8