[llvm] r182704 - Track IR ordering of SelectionDAG nodes 3/4.

[Cameron Zwarich]

I am seeing some issues introduced by this patch (or the next patch, I had to revert them together). I now see DBG_VALUE instructions inserted between two terminators of an MBB, which the verifier complains about. Some pass (I didn't track down which) is confused by this and drops CFG edges between basic blocks, leading to a jump with a target of BB#-1 when a block is removed for having no predecessors.

Cameron