IR: Split GenericMDNode into MDTuple and UniquableMDNode

Split `GenericMDNode` into two classes (with more descriptive names).

  - `UniquableMDNode` will be a common subclass for `MDNode`s that are
    sometimes uniqued like constants, and sometimes 'distinct'.

    This class gets the (short-lived) RAUW support and related API.

  - `MDTuple` is the basic tuple that has always been returned by
    `MDNode::get()`.  This is as opposed to more specific nodes to be
    added soon, which have additional fields, custom assembly syntax,
    and extra semantics.

    This class gets the hash-related logic, since other sublcasses of
    `UniquableMDNode` may need to hash based on other fields.

To keep this diff from getting too big, I've added casts to `MDTuple`
that won't really scale as new subclasses of `UniquableMDNode` are
added, but I'll clean those up incrementally.

(No functionality change intended.)

llvm-svn: 225682

1 files changed, 10 insertions, 10 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 7c34f09..a9268b4 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -135,17 +135,17 @@ LLVMContextImpl::~LLVMContextImpl() {
   for (auto &Pair : ValuesAsMetadata)
     delete Pair.second;
 
-  // Destroy MDNodes.  ~MDNode can move and remove nodes between the MDNodeSet
-  // and the NonUniquedMDNodes sets, so copy the values out first.
-  SmallVector<GenericMDNode *, 8> MDNodes;
-  MDNodes.reserve(MDNodeSet.size() + NonUniquedMDNodes.size());
-  MDNodes.append(MDNodeSet.begin(), MDNodeSet.end());
-  MDNodes.append(NonUniquedMDNodes.begin(), NonUniquedMDNodes.end());
-  for (GenericMDNode *I : MDNodes)
+  // Destroy MDNodes.  ~MDNode can move and remove nodes between the MDTuples
+  // and the DistinctMDNodes sets, so copy the values out first.
+  SmallVector<UniquableMDNode *, 8> Uniquables;
+  Uniquables.reserve(MDTuples.size() + DistinctMDNodes.size());
+  Uniquables.append(MDTuples.begin(), MDTuples.end());
+  Uniquables.append(DistinctMDNodes.begin(), DistinctMDNodes.end());
+  for (UniquableMDNode *I : Uniquables)
     I->dropAllReferences();
-  for (GenericMDNode *I : MDNodes)
-    delete I;
-  assert(MDNodeSet.empty() && NonUniquedMDNodes.empty() &&
+  for (UniquableMDNode *I : Uniquables)
+    delete cast<MDTuple>(I);
+  assert(MDTuples.empty() && DistinctMDNodes.empty() &&
          "Destroying all MDNodes didn't empty the Context's sets.");
 
   // Destroy MDStrings.