[Cloning] Clone metadata on function declarations

Previously we missed cloning metadata on function declarations because
we don't call CloneFunctionInto() on declarations in CloneModule().

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D113812

Author: aeubanks

llvm/lib/Transforms/Utils/CloneModule.cpp

@@ -142,10 +142,18 @@ std::unique_ptr<Module> llvm::CloneModule(
   // Similarly, copy over function bodies now...
   //
   for (const Function &I : M) {
-    if (I.isDeclaration())
+    Function *F = cast<Function>(VMap[&I]);
+
+    if (I.isDeclaration()) {
+      // Copy over metadata for declarations since we're not doing it below in
+      // CloneFunctionInto().
+      SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
+      I.getAllMetadata(MDs);
+      for (auto MD : MDs)
+        F->addMetadata(MD.first, *MapMetadata(MD.second, VMap));
       continue;
+    }
 
-    Function *F = cast<Function>(VMap[&I]);
     if (!ShouldCloneDefinition(&I)) {
       // Skip after setting the correct linkage for an external reference.
       F->setLinkage(GlobalValue::ExternalLinkage);

llvm/unittests/Transforms/Utils/CloningTest.cpp

@@ -882,6 +882,10 @@ class CloneModule : public ::testing::Test {
     IBuilder.SetInsertPoint(Entry);
     IBuilder.CreateRetVoid();
 
+    auto *G =
+        Function::Create(FuncType, GlobalValue::ExternalLinkage, "g", OldM);
+    G->addMetadata(LLVMContext::MD_type, *MDNode::get(C, {}));
+
     // Finalize the debug info
     DBuilder.finalize();
   }
@@ -894,7 +898,11 @@ class CloneModule : public ::testing::Test {
 };
 
 TEST_F(CloneModule, Verify) {
-  EXPECT_FALSE(verifyModule(*NewM));
+  // Confirm the old module is (still) valid.
+  EXPECT_FALSE(verifyModule(*OldM, &errs()));
+
+  // Check the new module.
+  EXPECT_FALSE(verifyModule(*NewM, &errs()));
 }
 
 TEST_F(CloneModule, OldModuleUnchanged) {
@@ -912,6 +920,11 @@ TEST_F(CloneModule, Subprogram) {
   EXPECT_EQ(SP->getLine(), (unsigned)4);
 }
 
+TEST_F(CloneModule, FunctionDeclarationMetadata) {
+  Function *NewF = NewM->getFunction("g");
+  EXPECT_NE(nullptr, NewF->getMetadata(LLVMContext::MD_type));
+}
+
 TEST_F(CloneModule, GlobalMetadata) {
   GlobalVariable *NewGV = NewM->getGlobalVariable("gv");
   EXPECT_NE(nullptr, NewGV->getMetadata(LLVMContext::MD_type));