[InstCombine] Be more conservative about removing stackrestore

We ended up removing a save/restore pair around an inalloca call,
leading to a miscompile in Chromium.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262095 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed