Fixed bug in SmallDenseMap where it wouldn't leave enough space for an empty bucket...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166492 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index cbcf7892c97004c01d0cd6263b1bd3ed9d16682c..0ae54f429267efe72022bc99742f764689335da4 100644 (file)
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -826,11 +826,11 @@ public:
   }
 
   void grow(unsigned AtLeast) {
-    if (AtLeast > InlineBuckets)
+    if (AtLeast >= InlineBuckets)
       AtLeast = std::max<unsigned>(64, NextPowerOf2(AtLeast));
 
     if (Small) {
-      if (AtLeast <= InlineBuckets)
+      if (AtLeast < InlineBuckets)
         return; // Nothing to do.
 
       // First move the inline buckets into a temporary storage.

diff --git a/unittests/ADT/DenseMapTest.cpp b/unittests/ADT/DenseMapTest.cpp
index 75e7006434a007aebd724bcdc47a1ce4cfcb0518..15eb6988f669058154407df6f4402b64b015340d 100644 (file)
--- a/unittests/ADT/DenseMapTest.cpp
+++ b/unittests/ADT/DenseMapTest.cpp
@@ -330,4 +330,37 @@ TEST(DenseMapCustomTest, FindAsTest) {
   EXPECT_TRUE(map.find_as("d") == map.end());
 }
 
+struct ContiguousDenseMapInfo {
+  static inline unsigned getEmptyKey() { return ~0; }
+  static inline unsigned getTombstoneKey() { return ~0U - 1; }
+  static unsigned getHashValue(const unsigned& Val) { return Val; }
+  static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
+    return LHS == RHS;
+  }
+};
+
+// Test that filling a small dense map with exactly the number of elements in
+// the map grows to have enough space for an empty bucket.
+TEST(DenseMapCustomTest, SmallDenseMapGrowTest) {
+  SmallDenseMap<unsigned, unsigned, 32, ContiguousDenseMapInfo> map;
+  // Add some number of elements, then delete a few to leave us some tombstones.
+  // If we just filled the map with 32 elements we'd grow because of not enough
+  // tombstones which masks the issue here.
+  for (unsigned i = 0; i < 20; ++i)
+    map[i] = i + 1;
+  for (unsigned i = 0; i < 10; ++i)
+    map.erase(i);
+  for (unsigned i = 20; i < 32; ++i)
+    map[i] = i + 1;
+
+  // Size tests
+  EXPECT_EQ(22u, map.size());
+
+  // Try to find an element which doesn't exist.  There was a bug in
+  // SmallDenseMap which led to a map with num elements == small capacity not
+  // having an empty bucket any more.  Finding an element not in the map would
+  // therefore never terminate.
+  EXPECT_TRUE(map.find(32) == map.end());
+}
+
 }