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, 2 insertions, 2 deletions

diff --git a/llvm/lib/IR/MetadataTracking.cpp b/llvm/lib/IR/MetadataTracking.cpp
index 5b4b55586a9..ba97ca033a4 100644
--- a/llvm/lib/IR/MetadataTracking.cpp
+++ b/llvm/lib/IR/MetadataTracking.cpp
@@ -18,8 +18,8 @@ using namespace llvm;
 
 ReplaceableMetadataImpl *ReplaceableMetadataImpl::get(Metadata &MD) {
   if (auto *N = dyn_cast<MDNode>(&MD)) {
-    if (auto *G = dyn_cast<GenericMDNode>(N))
-      return G->ReplaceableUses.get();
+    if (auto *U = dyn_cast<UniquableMDNode>(N))
+      return U->ReplaceableUses.get();
     return cast<MDNodeFwdDecl>(N);
   }
   return dyn_cast<ValueAsMetadata>(&MD);