Add support for a new extension to the .file directive:

  .file filenumber "directory" "filename"

This removes one join+split of the directory+filename in MC internals. Because
bitcode files have independent fields for directory and filenames in debug info,
this patch may change the .o files written by existing .bc files.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142300 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index a6c0adb..d178b50 100644
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -83,7 +83,8 @@
                                    unsigned char Value = 0) {}
     
     virtual void EmitFileDirective(StringRef Filename) {}
-    virtual bool EmitDwarfFileDirective(unsigned FileNo,StringRef Filename) {
+    virtual bool EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
+                                        StringRef Filename) {
       return false;
     }
     virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,