Summary:
-mldst-motion creates a new phi node without any debug info. Use the merged debug location from the incoming stores to fix this.
Fixes PR38177. The test case here is (somewhat) simplified from:
```
struct S {
int foo;
void fn(int bar);
};
void S::fn(int bar) {
if (bar)
foo = 1;
else
foo = 0;
}
```
Reviewers: dblaikie, gbedwell, aprantl, vsk
Reviewed By: vsk
Subscribers: vsk, JDevlieghere, llvm-commits
Tags: #debug-info
Differential Revision: https://reviews.llvm.org/D54019
llvm-svn: 346027