ValueMapper: Add support for seeding metadata with nullptr

Support seeding a ValueMap with nullptr for Metadata entries, a
situation I didn't consider in the Metadata/Value split.

I added a ValueMapper::getMappedMD accessor that returns an
Optional<Metadata*> with the mapped (possibly null) metadata.  IRMover
needs to use this to avoid modifying the map when it's checking for
unneeded subprograms.  I updated a call from bugpoint since I find the
new code clearer.

llvm-svn: 265228

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp b/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
index 6141c41..3c7ef1b 100644
--- a/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
+++ b/llvm/unittests/Transforms/Utils/ValueMapperTest.cpp
@@ -55,4 +55,30 @@ TEST(ValueMapperTest, MapMetadataDistinctOperands) {
   EXPECT_EQ(New, D->getOperand(0));
 }
 
+TEST(ValueMapperTest, MapMetadataSeeded) {
+  LLVMContext Context;
+  auto *D = MDTuple::getDistinct(Context, None);
+
+  // The node should be moved.
+  ValueToValueMapTy VM;
+  EXPECT_EQ(None, VM.getMappedMD(D));
+
+  VM.MD().insert(std::make_pair(D, TrackingMDRef(D)));
+  EXPECT_EQ(D, *VM.getMappedMD(D));
+  EXPECT_EQ(D, MapMetadata(D, VM, RF_None));
+}
+
+TEST(ValueMapperTest, MapMetadataSeededWithNull) {
+  LLVMContext Context;
+  auto *D = MDTuple::getDistinct(Context, None);
+
+  // The node should be moved.
+  ValueToValueMapTy VM;
+  EXPECT_EQ(None, VM.getMappedMD(D));
+
+  VM.MD().insert(std::make_pair(D, TrackingMDRef()));
+  EXPECT_EQ(nullptr, *VM.getMappedMD(D));
+  EXPECT_EQ(nullptr, MapMetadata(D, VM, RF_None));
+}
+
 } // end namespace