[llvm] XCOFF associated metadata (PR #159096)

[Wael Yehia via llvm-commits]

================
@@ -8440,6 +8440,35 @@ Example:
 The ``nofree`` metadata indicates the memory pointed by the pointer will not be
 freed after the attached instruction.
 
+'``ref``' Metadata
+^^^^^^^^^^^^^^^^^^
+
+The ``ref`` metadata may be attached to a global variable definition with a
----------------
w2yehia wrote:

Before talking about the `.ref` directive I think it's better to first mention that this is XCOFF only, that way the reader can infer that `.ref` is some target specific assembly directive.

https://github.com/llvm/llvm-project/pull/159096