[llvm] [ctx_prof] CtxProfAnalysis: populate module data (PR #102930)

[Mircea Trofin via llvm-commits]

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@@ -24,5 +24,26 @@ class PGOCtxProfLoweringPass : public PassInfoMixin<PGOCtxProfLoweringPass> {
 
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
 };
+
+/// Assign a GUID to functions as metadata. GUID calculation takes linkage into
+/// account, which may change especially through and after thinlto. By
+/// pre-computing and assigning as metadata, this mechanism is resilient to such
+/// changes (as well as name changes e.g. suffix ".llvm." additions). It's
+/// arguably a much simpler mechanism than PGO's current GV-based one, and can
+/// be made available more broadly.
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mtrofin wrote:

It should also change at that point because this whole thing would move out :) But removed that bit.

https://github.com/llvm/llvm-project/pull/102930