[PATCH] D43690: [ThinLTO] Keep available_externally symbols live

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added inline comments.


================
Comment at: lib/Transforms/IPO/FunctionImport.cpp:620
+      for (auto &S : VI.getSummaryList())
+        if (S->linkage() != GlobalValue::AvailableExternallyLinkage)
+          return;
----------------
tejohnson wrote:
> Is it possible to have a symbol that is weak in one module and available_externally in another? If so, it would be more correct to return only if none of the copies is available_externally.
I suppose so. In the situation where we have at least one available-externally we could end up needing a symbol referenced by the available-externally as a result of a backend inlining it into a caller. So we would need to keep them live anyway.

Now that I think about it, this applies to linkonce-odr as well (i.e. we could convert them to available-externally as a result of non-prevailing, and then inline them in the backend and thus end up needing a symbol that was referenced by the available-externally but not necessarily by the prevailing copy of the global). But that's somewhat of an orthogonal problem to this.


Repository:
  rL LLVM

https://reviews.llvm.org/D43690