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/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index bcb314dfbd7..b33d6ad35c9 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -169,8 +169,8 @@ bool LLParser::ValidateEndOfModule() {
 
   // Resolve metadata cycles.
   for (auto &N : NumberedMetadata)
-    if (auto *G = cast_or_null<GenericMDNode>(N))
-      G->resolveCycles();
+    if (auto *U = cast_or_null<UniquableMDNode>(N))
+      U->resolveCycles();
 
   // Look for intrinsic functions and CallInst that need to be upgraded
   for (Module::iterator FI = M->begin(), FE = M->end(); FI != FE; )