[heap] Infer native context for each JSObject for memory measurement

Bug: chromium:973627

Change-Id: Ie9b07075604451636967b69b30f276fb45bc5372
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2011824
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65934}

src/heap/memory-measurement.cc

@@ -333,8 +333,13 @@ bool NativeContextInferrer::InferForJSObject(Isolate* isolate, Map map,
       return true;
     }
   }
-  // TODO(ulan): Add a more precise inference for the case when
-  // the current context is the shared context.
+  // The maximum number of steps to perform when looking for the context.
+  const int kMaxSteps = 3;
+  Object maybe_constructor = map.TryGetConstructor(isolate, kMaxSteps);
+  if (maybe_constructor.IsJSFunction()) {
+    return InferForJSFunction(JSFunction::cast(maybe_constructor),
+                              native_context);
+  }
   return false;
 }
 

test/cctest/heap/test-memory-measurement.cc

@@ -51,6 +51,7 @@ TEST(NativeContextInferrerJSObject) {
   LocalContext env;
   Isolate* isolate = CcTest::i_isolate();
   HandleScope scope(isolate);
+  Handle<NativeContext> native_context = GetNativeContext(isolate, env.local());
   v8::Local<v8::Value> result = CompileRun("({a : 10})");
   Handle<Object> object = Utils::OpenHandle(*result);
   Handle<HeapObject> function = Handle<HeapObject>::cast(object);
@@ -58,8 +59,8 @@ TEST(NativeContextInferrerJSObject) {
   Address inferred_context = 0;
   // TODO(ulan): Enable this test once we have more precise native
   // context inference.
-  CHECK(
-      !inferrer.Infer(isolate, function->map(), *function, &inferred_context));
+  CHECK(inferrer.Infer(isolate, function->map(), *function, &inferred_context));
+  CHECK_EQ(native_context->ptr(), inferred_context);
 }
 
 TEST(NativeContextStatsMerge) {