[DSE] add test for PR36129; NFC

We can miscompile because we're not checking is the memory might
me modified between the seemingly redundant store ops.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323704 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed