This also implements a two minor improvements:
* Don't insert live-out stores IN the region, insert them on the code path
that exits the region
* If the region is exited to the same block from multiple paths, share the
switch statement entry, live-out store code, and the basic block.
llvm-svn: 12401
a member of the class. While we're at it, turn the collection into a set
instead of a vector to improve efficiency and make queries simpler.
llvm-svn: 12400
