https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63572
--- Comment #31 from Jakub Jelinek <jakub at gcc dot gnu.org> --- In theory, what we could do (expensive though) is keep the IL of the functions that were ICF merged with the picked up candidate, just mark them in cgraph specially so that e.g. IPA doesn't consider references to functions/vars from the other copies as distinct references, compile those functions right after compiling their chosen ICF winner (or right before it), but don't emit into assembly, instead compare with how the ICF winner and emit just debug info for the other copies after building some mapping between the debug related labels in the different functions. If we compiled it into different code, something bad happened (e.g. some debug counter or similar) and we'd just not emit the debug info for the other copies (like we don't emit it currently for those).
