Improve base::RandBytes() performance by 1.75x-2.10x on POSIX.

base/rand_util.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/rand_util.h"
 
 #include <math.h>
 
 #include <algorithm>
 #include <limits>
@@ skipping 43 matching lines @@
       (std::numeric_limits<uint64>::max() / range) * range - 1;
 
   uint64 value;
   do {
     value = base::RandUint64();
   } while (value > max_acceptable_value);
 
   return value % range;
 }
 
-void RandBytes(void* output, size_t output_length) {
-  uint64 random_int;
-  size_t random_int_size = sizeof(random_int);
-  for (size_t i = 0; i < output_length; i += random_int_size) {
-    random_int = base::RandUint64();
-    size_t copy_count = std::min(output_length - i, random_int_size);
-    memcpy(((uint8*)output) + i, &random_int, copy_count);
-  }
-}
-
 std::string RandBytesAsString(size_t length) {
   DCHECK_GT(length, 0u);
   std::string result;
   RandBytes(WriteInto(&result, length + 1), length);
   return result;
 }
 
 }  // namespace base