1 files changed, 45 insertions, 0 deletions
diff --git a/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp b/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
index 3c7ef1b686a..865cb5d0d7c 100644
--- a/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
+++ b/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
@@ -16,6 +16,51 @@ using namespace llvm;
 
 namespace {
 
+TEST(ValueMapperTest, MapMetadata) {
+  LLVMContext Context;
+  auto *U = MDTuple::get(Context, None);
+
+  // The node should be unchanged.
+  ValueToValueMapTy VM;
+  EXPECT_EQ(U, MapMetadata(U, VM, RF_None));
+}
+
+TEST(ValueMapperTest, MapMetadataCycle) {
+  LLVMContext Context;
+  MDNode *U0;
+  MDNode *U1;
+  {
+    Metadata *Ops[] = {nullptr};
+    auto T = MDTuple::getTemporary(Context, Ops);
+    Ops[0] = T.get();
+    U0 = MDTuple::get(Context, Ops);
+    T->replaceOperandWith(0, U0);
+    U1 = MDNode::replaceWithUniqued(std::move(T));
+    U0->resolveCycles();
+  }
+
+  EXPECT_TRUE(U0->isResolved());
+  EXPECT_TRUE(U0->isUniqued());
+  EXPECT_TRUE(U1->isResolved());
+  EXPECT_TRUE(U1->isUniqued());
+  EXPECT_EQ(U1, U0->getOperand(0));
+  EXPECT_EQ(U0, U1->getOperand(0));
+
+  // Cycles shouldn't be duplicated.
+  {
+    ValueToValueMapTy VM;
+    EXPECT_EQ(U0, MapMetadata(U0, VM, RF_None));
+    EXPECT_EQ(U1, MapMetadata(U1, VM, RF_None));
+  }
+
+  // Check the other order.
+  {
+    ValueToValueMapTy VM;
+    EXPECT_EQ(U1, MapMetadata(U1, VM, RF_None));
+    EXPECT_EQ(U0, MapMetadata(U0, VM, RF_None));
+  }
+}
+
 TEST(ValueMapperTest, MapMetadataUnresolved) {
   LLVMContext Context;
   TempMDTuple T = MDTuple::getTemporary(Context, None);