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

2 files changed, 53 insertions, 0 deletions

diff --git a/test/libcxx/utilities/function.objects/unord.hash/murmur2_or_cityhash_ubsan_unsigned_overflow_ignored.pass.cpp b/test/libcxx/utilities/function.objects/unord.hash/murmur2_or_cityhash_ubsan_unsigned_overflow_ignored.pass.cpp
new file mode 100644
index 000000000..319a78b05
--- /dev/null
+++ b/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());
+}
diff --git a/test/support/test_macros.h b/test/support/test_macros.h
index 431ca8a3e..cec5f5a5e 100644
--- a/test/support/test_macros.h
+++ b/test/support/test_macros.h
@@ -182,6 +182,18 @@ struct is_same<T, T> { enum {value = 1}; };
 #endif
 #endif
 
+#if defined(__GNUC__) || defined(__clang__)
+template <class Tp>
+inline void DoNotOptimize(Tp const& value) {
+  asm volatile("" : : "g"(value) : "memory");
+}
+#else
+template <class Tp>
+inline void DoNotOptimize(Tp const&) {
+  // FIXME: Do something here...
+}
+#endif
+
 #if defined(__GNUC__)
 #pragma GCC diagnostic pop
 #endif