Revert r282168 "GVN-hoist: fix store past load dependence analysis (PR30216)"

and also the dependent r282175 "GVN-hoist: do not dereference null pointers"

It's causing compiler crashes building Harfbuzz (PR30499).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282199 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed