Track JS allocations as they arrive with no affection on performance when tracking is switched off

test/cctest/test-heap-profiler.cc

 // Copyright 2011 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
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@@ skipping 1987 matching lines @@
       heap_profiler->TakeHeapSnapshot(v8_str("snapshot"));
   CHECK(ValidateSnapshot(snapshot));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* foo_func =
       GetProperty(global, v8::HeapGraphEdge::kProperty, "foo");
   CHECK_NE(NULL, foo_func);
   const v8::HeapGraphNode* code =
       GetProperty(foo_func, v8::HeapGraphEdge::kInternal, "code");
   CHECK_NE(NULL, code);
 }
+
+
+// This is an example of using checking of JS allocations tracking in a test.

[Hannes Payer (out of office), 2013/10/02 18:00:29]

Either remove the test if it is not testing anything or add a proper test. I
would prefer adding a proper test.

[Alexandra Mikhaylova, 2013/10/03 16:27:55]

This test checks that we don't miss some simplest allocations and
HeapObjectsTracker works correctly. In the HeapObjectsTracker constructor,
allocations tracking is switched on. In the destructor, allocations tracking is
checked and untracked objects are found (if any).

[Hannes Payer (out of office), 2013/10/10 18:54:40]

Sure, but wouldn't it make sense to check which objects are found?

+TEST(HeapObjectsTracker) {
+  LocalContext env;
+  v8::HandleScope scope(env->GetIsolate());
+  HeapObjectsTracker tracker;
+  CompileRun("var a = 1.2");
+  CompileRun("var a = 1.2; var b = 1.0; var c = 1.0;");
+  CompileRun(
+    "var a = [];"
+    "for (var i = 0; i < 5; ++i)"
+    "    a[i] = i;\n"
+    "for (var i = 0; i < 3; ++i)"
+    "    a.shift();\n"
+    );
+}