do some common stuff, then on our own add an object file writer (by calling
a concrete function), and then do some finishing stuff, if need be.
llvm-svn: 34032
empty ranges.
2. Reorg how MachineDebugInfo maintains changes to debug labels.
3. Have dwarf writer use debug label info to simplify scopes and source line
coorespondence.
4. Revert the merging of compile units until I can get the bugs ironed out.
llvm-svn: 31507