IR: Split MDNode into GenericMDNode and MDNodeFwdDecl

Split `MDNode` into two classes:

  - `GenericMDNode`, which is uniquable (and for now, always starts
    uniqued).  Once `Metadata` is split from the `Value` hierarchy, this
    class will lose the ability to RAUW itself.

  - `MDNodeFwdDecl`, which is used for the "temporary" interface, is
    never uniqued, and isn't managed by `LLVMContext` at all.

I've left most of the guts in `MDNode` for now, but I'll incrementally
move things to the right places (or delete the functionality, as
appropriate).

Part of PR21532.

llvm-svn: 222205

1 files changed, 3 insertions, 4 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index cd9da0d..d4239e5 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -122,13 +122,12 @@ LLVMContextImpl::~LLVMContextImpl() {
 
   // Destroy MDNodes.  ~MDNode can move and remove nodes between the MDNodeSet
   // and the NonUniquedMDNodes sets, so copy the values out first.
-  SmallVector<MDNode*, 8> MDNodes;
+  SmallVector<GenericMDNode *, 8> MDNodes;
   MDNodes.reserve(MDNodeSet.size() + NonUniquedMDNodes.size());
   MDNodes.append(MDNodeSet.begin(), MDNodeSet.end());
   MDNodes.append(NonUniquedMDNodes.begin(), NonUniquedMDNodes.end());
-  for (SmallVectorImpl<MDNode *>::iterator I = MDNodes.begin(),
-         E = MDNodes.end(); I != E; ++I)
-    (*I)->destroy();
+  for (auto &I : MDNodes)
+    I->destroy();
   assert(MDNodeSet.empty() && NonUniquedMDNodes.empty() &&
          "Destroying all MDNodes didn't empty the Context's sets.");