Fix PR13148, an inf-loop in StringMap.
StringMap suffered from the same bug as DenseMap: when you explicitly
construct it with a small number of buckets, you can arrange for the
tombstone-based growth path to be followed when the number of buckets
was less than '8'. In that case, even with a full map, it would compare
'0' as not less than '0', and refuse to grow the table, leading to
inf-loops trying to find an empty bucket on the next insertion. The fix
is very simple: use '<=' as the comparison. The same fix was applied to
DenseMap as well during its recent refactoring.
Thanks to Alex Bolz for the great report and test case. =]
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158725 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/ADT/StringMapTest.cpp b/unittests/ADT/StringMapTest.cpp
index 66e0493..5bb65cb 100644
--- a/unittests/ADT/StringMapTest.cpp
+++ b/unittests/ADT/StringMapTest.cpp
@@ -134,6 +134,28 @@
assertSingleItemMap();
}
+TEST_F(StringMapTest, SmallFullMapTest) {
+ // StringMap has a tricky corner case when the map is small (<8 buckets) and
+ // it fills up through a balanced pattern of inserts and erases. This can
+ // lead to inf-loops in some cases (PR13148) so we test it explicitly here.
+ llvm::StringMap<int> Map(2);
+
+ Map["eins"] = 1;
+ Map["zwei"] = 2;
+ Map["drei"] = 3;
+ Map.erase("drei");
+ Map.erase("eins");
+ Map["veir"] = 4;
+ Map["funf"] = 5;
+
+ EXPECT_EQ(3u, Map.size());
+ EXPECT_EQ(0, Map.lookup("eins"));
+ EXPECT_EQ(2, Map.lookup("zwei"));
+ EXPECT_EQ(0, Map.lookup("drei"));
+ EXPECT_EQ(4, Map.lookup("veir"));
+ EXPECT_EQ(5, Map.lookup("funf"));
+}
+
// A more complex iteration test.
TEST_F(StringMapTest, IterationTest) {
bool visited[100];