[llvm] XCOFF associated metadata (PR #159096)

[Wael Yehia via llvm-commits]

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@@ -8157,6 +8158,23 @@ Example:
     @b = internal global i32 2, comdat $a, section "abc", !associated !0
     !0 = !{ptr @a}
 
+XCOFF Targets
+"""""""""""""
+
+This metadata lowers to the .ref assembly directive which will add a relocation
+representing an implicit reference from the section the global belongs to, to
+the associated symbol. This link will keep the associated symbol alive if the
+section is not garbage collected. More than one associated node can be attached
+to the same global variable.
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w2yehia wrote:

The verifier currently checks the first `!associated`, but now it should be taught to check many.

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