1 files changed, 5 insertions, 0 deletions
diff --git a/include/llvm/ADT/SmallSet.h b/include/llvm/ADT/SmallSet.h
index 39a57b87b2a7..aaa5ff0ae939 100644
--- a/include/llvm/ADT/SmallSet.h
+++ b/include/llvm/ADT/SmallSet.h
@@ -38,6 +38,11 @@ class SmallSet {
   typedef typename SmallVector<T, N>::const_iterator VIterator;
   typedef typename SmallVector<T, N>::iterator mutable_iterator;
 
+  // In small mode SmallPtrSet uses linear search for the elements, so it is
+  // not a good idea to choose this value too high. You may consider using a
+  // DenseSet<> instead if you expect many elements in the set.
+  static_assert(N <= 32, "N should be small");
+
 public:
   typedef size_t size_type;
   SmallSet() {}