[GVNHoist] Properly merge alignments when hoisting

If we two loads of two different alignments, we must use the minimum of
the two alignments when hoisting.  Same deal for stores.

For allocas, use the maximum of the two allocas.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276601 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed