[NFC][Utils] Extract CloneFunctionMetadataInto from CloneFunctionInto (#118623)

Summary:
The new API expects the caller to populate the VMap. We need it this way
for a subsequent change around coroutine cloning.

Test Plan:
ninja check-llvm-unit check-llvm

Author: artempyanykh

llvm/include/llvm/Transforms/Utils/Cloning.h

@@ -182,6 +182,19 @@ void CloneFunctionAttributesInto(Function *NewFunc, const Function *OldFunc,
                                  ValueMapTypeRemapper *TypeMapper = nullptr,
                                  ValueMaterializer *Materializer = nullptr);
 
+/// Clone OldFunc's metadata into NewFunc.
+///
+/// The caller is expected to populate \p VMap beforehand and set an appropriate
+/// \p RemapFlag. Subprograms/CUs/types that were already mapped to themselves
+/// won't be duplicated.
+///
+/// NOTE: This function doesn't clone !llvm.dbg.cu when cloning into a different
+/// module. Use CloneFunctionInto for that behavior.
+void CloneFunctionMetadataInto(Function &NewFunc, const Function &OldFunc,
+                               ValueToValueMapTy &VMap, RemapFlags RemapFlag,
+                               ValueMapTypeRemapper *TypeMapper = nullptr,
+                               ValueMaterializer *Materializer = nullptr);
+
 void CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
                                const Instruction *StartingInst,
                                ValueToValueMapTy &VMap, bool ModuleLevelChanges,

llvm/lib/Transforms/Utils/CloneFunction.cpp

@@ -200,6 +200,19 @@ bool llvm::BuildDebugInfoMDMap(DenseMap<const Metadata *, TrackingMDRef> &MD,
   return ModuleLevelChanges;
 }
 
+void llvm::CloneFunctionMetadataInto(Function &NewFunc, const Function &OldFunc,
+                                     ValueToValueMapTy &VMap,
+                                     RemapFlags RemapFlag,
+                                     ValueMapTypeRemapper *TypeMapper,
+                                     ValueMaterializer *Materializer) {
+  SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
+  OldFunc.getAllMetadata(MDs);
+  for (auto MD : MDs) {
+    NewFunc.addMetadata(MD.first, *MapMetadata(MD.second, VMap, RemapFlag,
+                                               TypeMapper, Materializer));
+  }
+}
+
 // Clone OldFunc into NewFunc, transforming the old arguments into references to
 // VMap values.
 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
@@ -262,15 +275,9 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
       BuildDebugInfoMDMap(VMap.MD(), Changes, DIFinder, SPClonedWithinModule);
 
   const auto RemapFlag = ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges;
-  // Duplicate the metadata that is attached to the cloned function.
-  // Subprograms/CUs/types that were already mapped to themselves won't be
-  // duplicated.
-  SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
-  OldFunc->getAllMetadata(MDs);
-  for (auto MD : MDs) {
-    NewFunc->addMetadata(MD.first, *MapMetadata(MD.second, VMap, RemapFlag,
-                                                TypeMapper, Materializer));
-  }
+
+  CloneFunctionMetadataInto(*NewFunc, *OldFunc, VMap, RemapFlag, TypeMapper,
+                            Materializer);
 
   // Loop over all of the basic blocks in the function, cloning them as
   // appropriate.  Note that we save BE this way in order to handle cloning of