IR: Simplify uniquing for MDNode

Change uniquing from a `FoldingSet` to a `DenseSet` with custom
`DenseMapInfo`.  Unfortunately, this doesn't save any memory, since
`DenseSet<T>` is a simple wrapper for `DenseMap<T, char>`, but I'll come
back to fix that later.

I used the name `GenericDenseMapInfo` to the custom `DenseMapInfo` since
I'll be splitting `MDNode` into two classes soon: `MDNodeFwdDecl` for
temporaries, and `GenericMDNode` for everything else.

I also added a non-debug-info reduced version of a type-uniquing test
that started failing on an earlier draft of this patch.

Part of PR21532.

llvm-svn: 222191

1 files changed, 1 insertions, 3 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index df3449d12c8..cd9da0d0e08 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -124,9 +124,7 @@ LLVMContextImpl::~LLVMContextImpl() {
   // and the NonUniquedMDNodes sets, so copy the values out first.
   SmallVector<MDNode*, 8> MDNodes;
   MDNodes.reserve(MDNodeSet.size() + NonUniquedMDNodes.size());
-  for (FoldingSetIterator<MDNode> I = MDNodeSet.begin(), E = MDNodeSet.end();
-       I != E; ++I)
-    MDNodes.push_back(&*I);
+  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)