[Mem2Reg] Avoid replacing load with itself in promoteSingleBlockAlloca.

We do the same thing in rewriteSingleStoreAlloca.

Fixes PR37632.

Reviewers: chandlerc, davide, efriedma

Reviewed By: davide

Differential Revision: https://reviews.llvm.org/D47825


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334187 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed