Added flag for seeding the random generator deterministically.

src/v8.cc

 // Copyright 2006-2009 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
@@ skipping 137 matching lines @@
   Top::TearDown();
 
   Heap::TearDown();
   Logger::TearDown();
 
   is_running_ = false;
   has_been_disposed_ = true;
 }
 
 
+static uint32_t random_seed() {
+  if (FLAG_random_seed == 0) {
+    return random();
+  }
+  return FLAG_random_seed;
+}
+
+
 uint32_t V8::Random() {
   // Random number generator using George Marsaglia's MWC algorithm.
   static uint32_t hi = 0;
   static uint32_t lo = 0;
 
   // Initialize seed using the system random(). If one of the seeds
   // should ever become zero again, or if random() returns zero, we
   // avoid getting stuck with zero bits in hi or lo by re-initializing
   // them on demand.
-  if (hi == 0) hi = random();
-  if (lo == 0) lo = random();
+  if (hi == 0) hi = random_seed();
+  if (lo == 0) lo = random_seed();
 
   // Mix the bits.
   hi = 36969 * (hi & 0xFFFF) + (hi >> 16);
   lo = 18273 * (lo & 0xFFFF) + (lo >> 16);
   return (hi << 16) + (lo & 0xFFFF);
 }
 
 
 bool V8::IdleNotification() {
   // Returning true tells the caller that there is no need to call
   // IdleNotification again.
   if (!FLAG_use_idle_notification) return true;
 
   // Tell the heap that it may want to adjust.
   return Heap::IdleNotification();
 }
 
 static const uint32_t kRandomPositiveSmiMax = 0x3fffffff;
 
 Smi* V8::RandomPositiveSmi() {
   uint32_t random = Random();
   ASSERT(static_cast<uint32_t>(Smi::kMaxValue) >= kRandomPositiveSmiMax);
   // kRandomPositiveSmiMax must match the value being divided
   // by in math.js.
   return Smi::FromInt(random & kRandomPositiveSmiMax);
 }
 
 } }  // namespace v8::internal