IR: Remove MDNodeFwdDecl

Remove `MDNodeFwdDecl` (as promised in r226481).  Aside from API
changes, there's no real functionality change here.
`MDNode::getTemporary()` now forwards to `MDTuple::getTemporary()`,
which returns a tuple with `isTemporary()` equal to true.

The main point is that we can now add temporaries of other `MDNode`
subclasses, needed for PR22235 (I introduced `MDNodeFwdDecl` in the
first place because I didn't recognize this need, and thought they were
only needed to handle forward references).

A few things left out of (or highlighted by) this commit:

  - I've had to remove the (few) uses of `std::unique_ptr<>` to deal
    with temporaries, since the destructor is no longer public.
    `getTemporary()` should probably return the equivalent of
    `std::unique_ptr<T, MDNode::deleteTemporary>`.
  - `MDLocation::getTemporary()` doesn't exist yet (worse, it actually
    does exist, but does the wrong thing: `MDNode::getTemporary()` is
    inherited and returns an `MDTuple`).
  - `MDNode` now only has one subclass, `UniquableMDNode`, and the
    distinction between them is actually somewhat confusing.

I'll fix those up next.

llvm-svn: 226501

2 files changed, 8 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 2a86eb598d4..3cebd232984 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -319,11 +319,11 @@ static void CloneAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap) {
 
   // Now we have a complete set of all metadata in the chains used to specify
   // the noalias scopes and the lists of those scopes.
-  SmallVector<MDNode *, 16> DummyNodes;
+  SmallVector<MDTuple *, 16> DummyNodes;
   DenseMap<const MDNode *, TrackingMDNodeRef> MDMap;
   for (SetVector<const MDNode *>::iterator I = MD.begin(), IE = MD.end();
        I != IE; ++I) {
-    MDNode *Dummy = MDNode::getTemporary(CalledFunc->getContext(), None);
+    MDTuple *Dummy = MDTuple::getTemporary(CalledFunc->getContext(), None);
     DummyNodes.push_back(Dummy);
     MDMap[*I].reset(Dummy);
   }
@@ -343,7 +343,8 @@ static void CloneAliasScopeMetadata(CallSite CS, ValueToValueMapTy &VMap) {
     }
 
     MDNode *NewM = MDNode::get(CalledFunc->getContext(), NewOps);
-    MDNodeFwdDecl *TempM = cast<MDNodeFwdDecl>(MDMap[*I]);
+    MDTuple *TempM = cast<MDTuple>(MDMap[*I]);
+    assert(TempM->isTemporary() && "Expected temporary node");
 
     TempM->replaceAllUsesWith(NewM);
   }
diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 5d89858e527..b195c6349b7 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -249,12 +249,12 @@ static Metadata *mapDistinctNode(const UniquableMDNode *Node,
 
   // In general we need a dummy node, since whether the operands are null can
   // affect the size of the node.
-  std::unique_ptr<MDNodeFwdDecl> Dummy(
-      MDNode::getTemporary(Node->getContext(), None));
-  mapToMetadata(VM, Node, Dummy.get());
+  MDTuple *Dummy = MDTuple::getTemporary(Node->getContext(), None);
+  mapToMetadata(VM, Node, Dummy);
   Metadata *NewMD = cloneMDNode(Node, VM, Flags, TypeMapper, Materializer,
                                 /* IsDistinct */ true);
   Dummy->replaceAllUsesWith(NewMD);
+  MDNode::deleteTemporary(Dummy);
   return mapToMetadata(VM, Node, NewMD);
 }
 
@@ -285,7 +285,7 @@ static Metadata *mapUniquedNode(const UniquableMDNode *Node,
   assert(Node->isUniqued() && "Expected uniqued node");
 
   // Create a dummy node in case we have a metadata cycle.
-  MDNodeFwdDecl *Dummy = MDNode::getTemporary(Node->getContext(), None);
+  MDTuple *Dummy = MDTuple::getTemporary(Node->getContext(), None);
   mapToMetadata(VM, Node, Dummy);
 
   // Check all operands to see if any need to be remapped.