[PATCH] Add a fallback mechanism for undefined atom.

[Michael Spencer]

================
Comment at: lib/ReaderWriter/Native/NativeFileFormat.h:171-178
@@ -169,1 +170,10 @@
 
+//
+// The NCS_UndefinedAtomsV2 chunk contains an array of these structs
+//
+struct NativeUndefinedAtomIvarsV2 {
+  uint32_t  nameOffset;
+  uint32_t  flags;
+  uint32_t  fallbackNameOffset;
+};
+
----------------
Rui Ueyama wrote:
> Shankar Kalpathi Easwaran wrote:
> > We should just add the fallbackNameOffset to V1 (or) if you want to still do this, you could derive the second struct from the first one.
> > 
> > struct NativeUndefinedAtomIvarsV2 : public NativeUndefinedAtomIvarsV1
> done.
We are still modifying V1.

================
Comment at: test/core/undef-fallback.objtxt:13-14
@@ +12,4 @@
+  - name: foo
+    fallback:
+      name: bar
+...
----------------
Why isn't this just fallback: bar ?


http://llvm-reviews.chandlerc.com/D1550

COMMIT
  http://llvm-reviews.chandlerc.com/rL190625