[PATCH] D97735: [Globals] Treat nobuiltin fns as maybe-derefined.

[Florian Hahn via Phabricator via llvm-commits]

fhahn added inline comments.


================
Comment at: llvm/include/llvm/IR/GlobalValue.h:147
+      // derefined.
+      return isInterposable() || isNobuiltinFnDef();
     }
----------------
jdoerfert wrote:
> rsmith wrote:
> > I don't think `nobuiltin` is relevant; I think what matters is whether the function is a builtin function. We have the same miscompile if we removed all the `builtin` / `nobuiltin` annotations from the IR generated for the PR49022 example, and this change does nothing to address that case.
> So you are saying we can legally define our own `operator delete(void*) = _ZdlPv` without a `nobuiltin` attribute and that would still need to stop IPO from assuming it is the idealized version we all know and love?
I think the problem is how would we detect that a given global value may be used with builtin semantics? 

Do frontends create function definitions for recognized builtins without `nobuiltin`? If frontends need to do so, can they add an attribute to indicate that this functions may be used with some builtin semantics?


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D97735/new/

https://reviews.llvm.org/D97735