Avoid storing a directory name in both the DirEntries map keys and in the
UniqueDirs value.  Instead, just have the UniqueDirs value contain a pointer
to the key in the DirEntries map.

llvm-svn: 39083
diff --git a/clang/Basic/FileManager.cpp b/clang/Basic/FileManager.cpp
index c1520c8..5ee032e 100644
--- a/clang/Basic/FileManager.cpp
+++ b/clang/Basic/FileManager.cpp
@@ -59,11 +59,12 @@
   DirectoryEntry &UDE = 
     UniqueDirs[std::make_pair(StatBuf.st_dev, StatBuf.st_ino)];
   
-  if (UDE.getName()[0])  // Already have an entry with this inode, return it.
+  if (UDE.getName())  // Already have an entry with this inode, return it.
     return NamedDirEnt = &UDE;
   
-  // Otherwise, we don't have this directory yet, add it.
-  UDE.Name   = Filename;
+  // Otherwise, we don't have this directory yet, add it.  We use the string
+  // key from the DirEntries map as the string.
+  UDE.Name  = DirEntries.GetKeyForValueInMap(NamedDirEnt);
   return NamedDirEnt = &UDE;
 }