This speeds up the dependency calculations for blocks with many load/store/call instructions.
Beside the improved runtime, there is no functional change.
Compared to the original commit, this re-applied commit contains a bug fix which ensures that there are
no incorrect collisions in the alias cache.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225977 91177308-0d34-0410-b5e6-96231b3b80d8
d6238e7b7e