MapMetadata: Allow unresolved metadata if it won't change

Allow unresolved nodes through the `MapMetadata()` if
`RF_NoModuleLevelChanges`, since there's no remapping to do anyway.

This fixes PR22929.  I'll add a clang test as a follow-up.

llvm-svn: 232449

2 files changed, 28 insertions, 0 deletions

diff --git a/llvm/unittests/Transforms/Utils/CMakeLists.txt b/llvm/unittests/Transforms/Utils/CMakeLists.txt
index ffa1d49d380..517ff99ea46 100644
--- a/llvm/unittests/Transforms/Utils/CMakeLists.txt
+++ b/llvm/unittests/Transforms/Utils/CMakeLists.txt
@@ -9,4 +9,5 @@ add_llvm_unittest(UtilsTests
   Cloning.cpp
   IntegerDivision.cpp
   Local.cpp
+  ValueMapperTest.cpp
   )
diff --git a/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp b/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
new file mode 100644
index 00000000000..137a2607c84
--- /dev/null
+++ b/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
@@ -0,0 +1,27 @@
+//===- ValueMapper.cpp - Unit tests for ValueMapper -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(ValueMapperTest, MapMetadataUnresolved) {
+  LLVMContext Context;
+  TempMDTuple T = MDTuple::getTemporary(Context, None);
+
+  ValueToValueMapTy VM;
+  EXPECT_EQ(T.get(), MapMetadata(T.get(), VM, RF_NoModuleLevelChanges));
+}
+
+}