Prevent UBSAN from generating unsigned overflow diagnostics in the hashing internals

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294391 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/utilities/function.objects/unord.hash/murmur2_or_cityhash_ubsan_unsigned_overflow_ignored.pass.cpp

@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Test that UBSAN doesn't generate unsigned integer overflow diagnostics
+// from within the hashing internals.
+
+#include <utility>
+#include <cstdint>
+#include <limits>
+#include <string>
+
+#include "test_macros.h"
+
+typedef std::__murmur2_or_cityhash<uint32_t> Hash32;
+typedef std::__murmur2_or_cityhash<uint64_t> Hash64;
+
+void test(const void* key, int len) {
+  for (int i=1; i <= len; ++i) {
+    Hash32 h1;
+    Hash64 h2;
+    DoNotOptimize(h1(key, i));
+    DoNotOptimize(h2(key, i));
+  }
+}
+
+int main() {
+  const std::string TestCases[] = {
+      "abcdaoeuaoeclaoeoaeuaoeuaousaotehu]+}sthoasuthaoesutahoesutaohesutaoeusaoetuhasoetuhaoseutaoseuthaoesutaohes"
+      "00000000000000000000000000000000000000000000000000000000000000000000000",
+      "1237546895+54+4554985416849484213464984765465464654564565645645646546456546546"
+  };
+  const size_t NumCases = sizeof(TestCases)/sizeof(TestCases[0]);
+  for (size_t i=0; i < NumCases; ++i)
+    test(TestCases[i].data(), TestCases[i].length());
+}