Upstream version 9.37.197.0

[platform/framework/web/crosswalk.git] / src / v8 / src / utils / random-number-generator.cc

diff --git a/src/v8/src/utils/random-number-generator.cc b/src/v8/src/utils/random-number-generator.cc
index fe27331..3da6a5a 100644 (file)
--- a/src/v8/src/utils/random-number-generator.cc
+++ b/src/v8/src/utils/random-number-generator.cc
@@ -1,39 +1,17 @@
 // Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#include "utils/random-number-generator.h"
-
-#include <cstdio>
-#include <cstdlib>
-
-#include "flags.h"
-#include "platform/mutex.h"
-#include "platform/time.h"
-#include "utils.h"
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/utils/random-number-generator.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <new>
+
+#include "src/base/macros.h"
+#include "src/platform/mutex.h"
+#include "src/platform/time.h"
 
 namespace v8 {
 namespace internal {
@@ -50,12 +28,6 @@ void RandomNumberGenerator::SetEntropySource(EntropySource source) {
 
 
 RandomNumberGenerator::RandomNumberGenerator() {
-  // Check --random-seed flag first.
-  if (FLAG_random_seed != 0) {
-    SetSeed(FLAG_random_seed);
-    return;
-  }
-
   // Check if embedder supplied an entropy source.
   { LockGuard<Mutex> lock_guard(entropy_mutex.Pointer());
     if (entropy_source != NULL) {
@@ -110,7 +82,7 @@ int RandomNumberGenerator::NextInt(int max) {
   ASSERT_LE(0, max);
 
   // Fast path if max is a power of 2.
-  if (IsPowerOf2(max)) {
+  if (IS_POWER_OF_TWO(max)) {
     return static_cast<int>((max * static_cast<int64_t>(Next(31))) >> 31);
   }
 
@@ -140,7 +112,13 @@ void RandomNumberGenerator::NextBytes(void* buffer, size_t buflen) {
 int RandomNumberGenerator::Next(int bits) {
   ASSERT_LT(0, bits);
   ASSERT_GE(32, bits);
-  int64_t seed = (seed_ * kMultiplier + kAddend) & kMask;
+  // Do unsigned multiplication, which has the intended modulo semantics, while
+  // signed multiplication would expose undefined behavior.
+  uint64_t product = static_cast<uint64_t>(seed_) * kMultiplier;
+  // Assigning a uint64_t to an int64_t is implementation defined, but this
+  // should be OK. Use a static_cast to explicitly state that we know what we're
+  // doing. (Famous last words...)
+  int64_t seed = static_cast<int64_t>((product + kAddend) & kMask);
   seed_ = seed;
   return static_cast<int>(seed >> (48 - bits));
 }