global.cpp

// At this point, there shouldn't be any external references in the module
llvm::SmallVector<const llvm::GlobalValue*, 2> ExternalReferences;
for (const auto& GV : M->getGlobalList())
    if (GV.isDeclaration())
        ExternalReferences.push_back(&GV);
for (const auto& F : M->getFunctionList())
    if (F.isDeclaration() && !F.isIntrinsic())
        ExternalReferences.push_back(&F);
for (const auto* V: ExternalReferences) {
    JL_PRINTF(JL_STDERR, "Warning: detected use of external value '%s'\n",
                         V->getName());
    for (const auto& Use: V->uses()) {
        if (auto* I = llvm::dyn_cast<Instruction>(Use.getUser())) {
            if (llvm::MDNode *N = I->getMetadata("dbg")) {
                llvm::DILocation Loc(N);
                JL_PRINTF(JL_STDERR, " - at %s:%i\n",
                                     Loc.getFilename().str().data(),
                                     Loc.getLineNumber());
            }
        }
    }        
}