Add tests for *DenesMap for both key and value types' construction and
destruction and fix a bug in SmallDenseMap they caught.

This is kind of a poor-man's version of the testing that just adds the
addresses to a set on construction and removes them on destruction. We
check that double construction and double destruction don't occur.
Amusingly enough, this is enough to catch a lot of SmallDenseMap issues
because we spend a lot of time with fixed stable addresses in the inline
buffer.

The SmallDenseMap bug fix included makes grow() not double-destroy in
some cases. It also fixes a FIXME there, the code was pretty crappy. We
now don't have any wasted initialization, but we do move the entries in
inline bucket array an extra time. It's probably a better tradeoff, and
is much easier to get correct.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158639 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/ADT/DenseMapTest.cpp b/unittests/ADT/DenseMapTest.cpp
index d61f991..bd9a3f2 100644
--- a/unittests/ADT/DenseMapTest.cpp
+++ b/unittests/ADT/DenseMapTest.cpp
@@ -10,6 +10,7 @@
 #include "gtest/gtest.h"
 #include "llvm/ADT/DenseMap.h"
 #include <map>
+#include <set>
 
 using namespace llvm;
 
@@ -29,6 +30,47 @@
   return &dummy_arr1[i];
 }
 
+/// \brief A test class that tries to check that construction and destruction
+/// occur correctly.
+class CtorTester {
+  static std::set<CtorTester *> Constructed;
+  int Value;
+
+public:
+  explicit CtorTester(int Value = 0) : Value(Value) {
+    EXPECT_TRUE(Constructed.insert(this).second);
+  }
+  CtorTester(uint32_t Value) : Value(Value) {
+    EXPECT_TRUE(Constructed.insert(this).second);
+  }
+  CtorTester(const CtorTester &Arg) : Value(Arg.Value) {
+    EXPECT_TRUE(Constructed.insert(this).second);
+  }
+  ~CtorTester() {
+    EXPECT_EQ(1u, Constructed.erase(this));
+  }
+  operator uint32_t() const { return Value; }
+
+  int getValue() const { return Value; }
+  bool operator==(const CtorTester &RHS) const { return Value == RHS.Value; }
+};
+
+std::set<CtorTester *> CtorTester::Constructed;
+
+struct CtorTesterMapInfo {
+  static inline CtorTester getEmptyKey() { return CtorTester(-1); }
+  static inline CtorTester getTombstoneKey() { return CtorTester(-2); }
+  static unsigned getHashValue(const CtorTester &Val) {
+    return Val.getValue() * 37u;
+  }
+  static bool isEqual(const CtorTester &LHS, const CtorTester &RHS) {
+    return LHS == RHS;
+  }
+};
+
+CtorTester getTestKey(int i, CtorTester *) { return CtorTester(i); }
+CtorTester getTestValue(int i, CtorTester *) { return CtorTester(42 + i); }
+
 // Test fixture, with helper functions implemented by forwarding to global
 // function overloads selected by component types of the type parameter. This
 // allows all of the map implementations to be tested with shared
@@ -57,8 +99,11 @@
 // Register these types for testing.
 typedef ::testing::Types<DenseMap<uint32_t, uint32_t>,
                          DenseMap<uint32_t *, uint32_t *>,
+                         DenseMap<CtorTester, CtorTester, CtorTesterMapInfo>,
                          SmallDenseMap<uint32_t, uint32_t>,
-                         SmallDenseMap<uint32_t *, uint32_t *>
+                         SmallDenseMap<uint32_t *, uint32_t *>,
+                         SmallDenseMap<CtorTester, CtorTester, 4,
+                                       CtorTesterMapInfo>
                          > DenseMapTestTypes;
 TYPED_TEST_CASE(DenseMapTest, DenseMapTestTypes);