[llvm] XCOFF associated metadata (PR #159096)

[Fangrui Song via llvm-commits]

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@@ -8124,6 +8124,13 @@ See :doc:`CalleeTypeMetadata`.
 
 The ``associated`` metadata may be attached to a global variable definition with
 a single argument that references a global object (optionally through an alias).
+The metadata is often used with an explicit section consisting of valid C
+identifiers so that the runtime can find the metadata section with
+linker-defined encapsulation symbols ``__start_<section_name>`` and
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MaskRay wrote:

Will try to take a closer look tonight

Does XCOFF also use this naming convention

ELF uses this, see 
https://maskray.me/blog/2021-01-31-metadata-sections-comdat-and-shf-link-order "encapsulation symbols"

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