Merge remote-tracking branch 'aosp/upstream-master' into up-shaderc2

Refresh with content from github.com/google/re2
commit 79ef3b2d31f06493f687ef9e947d9632bad54b9b
date 2019-02-13

Change-Id: I4139f29d632e41722992309e96aca4f29c799c87

1 files changed, 41 insertions, 0 deletions

diff --git a/util/mix.h b/util/mix.h
new file mode 100644
index 0000000..d85c172
--- /dev/null
+++ b/util/mix.h
@@ -0,0 +1,41 @@
+// Copyright 2016 The RE2 Authors.  All Rights Reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#ifndef UTIL_MIX_H_
+#define UTIL_MIX_H_
+
+#include <stddef.h>
+#include <limits>
+
+namespace re2 {
+
+// Silence "truncation of constant value" warning for kMul in 32-bit mode.
+// Since this is a header file, push and then pop to limit the scope.
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable: 4309)
+#endif
+
+class HashMix {
+ public:
+  HashMix() : hash_(1) {}
+  explicit HashMix(size_t val) : hash_(val + 83) {}
+  void Mix(size_t val) {
+    static const size_t kMul = static_cast<size_t>(0xdc3eb94af8ab4c93ULL);
+    hash_ *= kMul;
+    hash_ = ((hash_ << 19) |
+             (hash_ >> (std::numeric_limits<size_t>::digits - 19))) + val;
+  }
+  size_t get() const { return hash_; }
+ private:
+  size_t hash_;
+};
+
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+}  // namespace re2
+
+#endif  // UTIL_MIX_H_