make tail merging more aggressive.  If two blocks share a common tail, but the
tail is not an entire block for either of them, pick one, split it, then
merge the common part.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31336 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed