--verify-predictable mode added for ensuring that GC behaves deterministically.

src/runtime.cc

 // Copyright 2012 the V8 project 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 <stdlib.h>
 #include <limits>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 9622 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_DateCurrentTime) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 0);
 
   // According to ECMA-262, section 15.9.1, page 117, the precision of
   // the number in a Date object representing a particular instant in
   // time is milliseconds. Therefore, we floor the result of getting
   // the OS time.
-  double millis = std::floor(OS::TimeCurrentMillis());
+  double millis;
+  if (FLAG_verify_predictable) {
+    millis = 1388534400000.0;  // Jan 1 2014 00:00:00 GMT+0000
+    millis += std::floor(isolate->heap()->allocations_count());
+  } else {
+    millis = std::floor(OS::TimeCurrentMillis());
+  }
   return *isolate->factory()->NewNumber(millis);
 }
 
 
 RUNTIME_FUNCTION(Runtime_DateParseString) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(String, str, 0);
   CONVERT_ARG_HANDLE_CHECKED(JSArray, output, 1);
 
@@ skipping 5490 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal