1 files changed, 49 insertions, 0 deletions
diff --git a/llvm/unittests/ADT/DenseMapTest.cpp b/llvm/unittests/ADT/DenseMapTest.cpp
index caeba457918..db00f8cf8e5 100644
--- a/llvm/unittests/ADT/DenseMapTest.cpp
+++ b/llvm/unittests/ADT/DenseMapTest.cpp
@@ -496,6 +496,55 @@ TEST(DenseMapCustomTest, StringRefTest) {
   EXPECT_EQ(42, M.lookup(StringRef("a", 0)));
 }
 
+struct CachedHashTest {
+  unsigned Val;
+  unsigned *Counter = nullptr;
+  CachedHashTest(unsigned Val) : Val(Val) {}
+  CachedHashTest(unsigned Val, unsigned *Counter)
+      : Val(Val), Counter(Counter) {}
+};
+}
+namespace llvm {
+template <> struct DenseMapInfo<CachedHashTest> {
+  static CachedHashTest getEmptyKey() { return ~0; }
+  static CachedHashTest getTombstoneKey() { return ~0U - 1; }
+  static unsigned getHashValue(const CachedHashTest &X) {
+    ++*X.Counter;
+    return X.Val;
+  }
+  static bool isEqual(const CachedHashTest &LHS, const CachedHashTest &RHS) {
+    return LHS.Val == RHS.Val;
+  }
+};
+}
+namespace {
+
+TEST(DenseMapCustomTest, CachedHashTest) {
+  unsigned Counter = 0;
+  CachedHashTest Val(0, &Counter);
+  DenseMap<CachedHashTest, int> Map;
+
+  Map[Val] = 0;
+  ASSERT_EQ(1u, Counter);
+
+  Map.reserve(64);
+  ASSERT_EQ(2u, Counter);
+}
+
+// Like above, but now cache the hash.
+TEST(DenseMapCustomTest, CachedHashTest2) {
+  unsigned Counter = 0;
+  CachedHashTest Val(0, &Counter);
+  typedef CachedHash<CachedHashTest> Cached;
+  DenseMap<Cached, int> Map;
+
+  Map[Val] = 0;
+  ASSERT_EQ(1u, Counter);
+
+  Map.reserve(64);
+  ASSERT_EQ(1u, Counter);
+}
+
 // Key traits that allows lookup with either an unsigned or char* key;
 // In the latter case, "a" == 0, "b" == 1 and so on.
 struct TestDenseMapInfo {