This is a fix for PR27844.
When replacing uses of unsafe allocas, emit the new location
immediately after each use. Without this, the pointer stays live from
the function entry to the last use, while it's usually cheaper to
recalculate.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@272969 91177308-0d34-0410-b5e6-96231b3b80d8
