[NFC][sanitizer] Add MurMur2Hash64Builder

Depends on D111176.

Differential Revision: https://reviews.llvm.org/D111177

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_hash.h

@@ -38,6 +38,30 @@ class MurMur2HashBuilder {
     return x;
   }
 };
+
+class MurMur2Hash64Builder {
+  static const u64 m = 0xc6a4a7935bd1e995ull;
+  static const u64 seed = 0x9747b28c9747b28cull;
+  static const u64 r = 47;
+  u64 h;
+
+ public:
+  explicit MurMur2Hash64Builder(u64 init = 0) { h = seed ^ (init * m); }
+  void add(u64 k) {
+    k *= m;
+    k ^= k >> r;
+    k *= m;
+    h ^= k;
+    h *= m;
+  }
+  u64 get() {
+    u64 x = h;
+    x ^= x >> r;
+    x *= m;
+    x ^= x >> r;
+    return x;
+  }
+};
 }  //namespace __sanitizer
 
 #endif  // SANITIZER_HASH_H

compiler-rt/lib/sanitizer_common/tests/sanitizer_hash_test.cpp

@@ -31,4 +31,18 @@ TEST(SanitizerCommon, Hash32Add) {
   EXPECT_EQ(h.get(), 2640061027u);
 }
 
+TEST(SanitizerCommon, Hash64Seed) {
+  EXPECT_EQ(MurMur2Hash64Builder(0).get(), 4469829599815726255ull);
+  EXPECT_EQ(MurMur2Hash64Builder(1).get(), 14121968454562043709ull);
+  EXPECT_EQ(MurMur2Hash64Builder(3).get(), 8040757559320203998ull);
+}
+
+TEST(SanitizerCommon, Hash64Add) {
+  MurMur2Hash64Builder h(123 * sizeof(u64));
+  for (u32 i = 0; i < 123; ++i) h.add(i);
+  EXPECT_EQ(h.get(), 11366430808886012537ull);
+  for (u32 i = 0; i < 123; ++i) h.add(-i);
+  EXPECT_EQ(h.get(), 10843188204560467446ull);
+}
+
 }  // namespace __sanitizer