Revert r276136 "Use ValueOffsetPair to enhance value reuse during SCEV expansion."

It causes Clang tests to fail after Windows self-host (PR28705).

(Also reverts follow-up r276139.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276822 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed