The pass manager is not able to schedule -loop-deletion -loop-index-split.

The pass manager is not able to schedule -loop-deletion -loop-index-split.

The loop-deletion pass does not preserve dom frontier, which is required by
loop-index-split. When the PM checks dom frontier for loop-index-split, it has
already verified that lcssa is availalble. However, new dom frontier forces new
loop pass manager, which does not  have lcssa yet.

The PM should recheck availability of required analysis passes in such cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54805 91177308-0d34-0410-b5e6-96231b3b80d8