When inserting expressions for post-increment users which contain

When inserting expressions for post-increment users which contain
loop-variant components, adds must be inserted after the increment.
Keep track of the increment position for this case, and insert
these adds in the correct location.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94110 91177308-0d34-0410-b5e6-96231b3b80d8