About MachineDominatorTree Pass.


I hope to cut all backedges of MachineFunction CFG, then topological sort MachineBasicBlocks.

1. MachineDominatorTree *domintree = new MachineDominatorTree();

2. Then travel mf one by one.
   When domintree->dominates(next,current) is true, there is a backedge from current node to next node. move this backedge form CFG.

   But I find A LOOP in some CFG, there is backedge from current to next, dominates function reture "FALSE". So my algorithm find Graph can not be
toplogical sort.

Is there a bug in MachineDominatorTree?? or MachineDominatorTree can not find all backedges???