[DWARF] Missing location debug information with -O2.

Check that Machine CSE correctly handles during the transformation, the
debug location information for local variables.

Differential Revision: https://reviews.llvm.org/D50887

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341025 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed