1 files changed, 165 insertions, 0 deletions
diff --git a/xpcom/tests/gtest/TestGCPostBarriers.cpp b/xpcom/tests/gtest/TestGCPostBarriers.cpp
new file mode 100644
index 0000000000..c32cd48c86
--- /dev/null
+++ b/xpcom/tests/gtest/TestGCPostBarriers.cpp
@@ -0,0 +1,165 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Tests that generational garbage collection post-barriers are correctly
+ * implemented for nsTArrays that contain JavaScript Values.
+ */
+
+#include "mozilla/UniquePtr.h"
+
+#include "jsapi.h"
+#include "nsTArray.h"
+
+#include "gtest/gtest.h"
+
+#include "js/PropertyAndElement.h"  // JS_GetProperty, JS_SetProperty
+#include "js/TracingAPI.h"
+#include "js/HeapAPI.h"
+
+#include "mozilla/CycleCollectedJSContext.h"
+
+using namespace mozilla;
+
+template <class ArrayT>
+static void TraceArray(JSTracer* trc, void* data) {
+  ArrayT* array = static_cast<ArrayT*>(data);
+  for (unsigned i = 0; i < array->Length(); ++i) {
+    JS::TraceEdge(trc, &array->ElementAt(i), "array-element");
+  }
+}
+
+/*
+ * Use arrays with initial size much smaller than the final number of elements
+ * to test that moving Heap<T> elements works correctly.
+ */
+const size_t ElementCount = 100;
+const size_t InitialElements = ElementCount / 10;
+
+template <class ArrayT>
+static void TestGrow(JSContext* cx) {
+  JS_GC(cx);
+
+  auto array = MakeUnique<ArrayT>();
+  ASSERT_TRUE(array != nullptr);
+
+  JS_AddExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
+
+  /*
+   * Create the array and fill it with new JS objects. With GGC these will be
+   * allocated in the nursery.
+   */
+  JS::RootedValue value(cx);
+  const char* property = "foo";
+  for (size_t i = 0; i < ElementCount; ++i) {
+    JS::RootedObject obj(cx, JS_NewPlainObject(cx));
+    ASSERT_FALSE(JS::ObjectIsTenured(obj));
+    value = JS::Int32Value(static_cast<int32_t>(i));
+    ASSERT_TRUE(JS_SetProperty(cx, obj, property, value));
+    ASSERT_TRUE(array->AppendElement(obj, fallible));
+  }
+
+  /*
+   * If postbarriers are not working, we will crash here when we try to mark
+   * objects that have been moved to the tenured heap.
+   */
+  JS_GC(cx);
+
+  /*
+   * Sanity check that our array contains what we expect.
+   */
+  ASSERT_EQ(array->Length(), ElementCount);
+  for (size_t i = 0; i < array->Length(); i++) {
+    JS::RootedObject obj(cx, array->ElementAt(i));
+    ASSERT_TRUE(JS::ObjectIsTenured(obj));
+    ASSERT_TRUE(JS_GetProperty(cx, obj, property, &value));
+    ASSERT_TRUE(value.isInt32());
+    ASSERT_EQ(static_cast<int32_t>(i), value.toInt32());
+  }
+
+  JS_RemoveExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
+}
+
+template <class ArrayT>
+static void TestShrink(JSContext* cx) {
+  JS_GC(cx);
+
+  auto array = MakeUnique<ArrayT>();
+  ASSERT_TRUE(array != nullptr);
+
+  JS_AddExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
+
+  /*
+   * Create the array and fill it with new JS objects. With GGC these will be
+   * allocated in the nursery.
+   */
+  JS::RootedValue value(cx);
+  const char* property = "foo";
+  for (size_t i = 0; i < ElementCount; ++i) {
+    JS::RootedObject obj(cx, JS_NewPlainObject(cx));
+    ASSERT_FALSE(JS::ObjectIsTenured(obj));
+    value = JS::Int32Value(static_cast<int32_t>(i));
+    ASSERT_TRUE(JS_SetProperty(cx, obj, property, value));
+    ASSERT_TRUE(array->AppendElement(obj, fallible));
+  }
+
+  /* Shrink and compact the array */
+  array->RemoveElementsAt(InitialElements, ElementCount - InitialElements);
+  array->Compact();
+
+  JS_GC(cx);
+
+  ASSERT_EQ(array->Length(), InitialElements);
+  for (size_t i = 0; i < array->Length(); i++) {
+    JS::RootedObject obj(cx, array->ElementAt(i));
+    ASSERT_TRUE(JS::ObjectIsTenured(obj));
+    ASSERT_TRUE(JS_GetProperty(cx, obj, property, &value));
+    ASSERT_TRUE(value.isInt32());
+    ASSERT_EQ(static_cast<int32_t>(i), value.toInt32());
+  }
+
+  JS_RemoveExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
+}
+
+template <class ArrayT>
+static void TestArrayType(JSContext* cx) {
+  TestGrow<ArrayT>(cx);
+  TestShrink<ArrayT>(cx);
+}
+
+static void CreateGlobalAndRunTest(JSContext* cx) {
+  static const JSClass GlobalClass = {"global", JSCLASS_GLOBAL_FLAGS,
+                                      &JS::DefaultGlobalClassOps};
+
+  JS::RealmOptions options;
+  // dummy
+  options.behaviors().setReduceTimerPrecisionCallerType(
+      JS::RTPCallerTypeToken{0});
+  JS::PersistentRootedObject global(cx);
+  global = JS_NewGlobalObject(cx, &GlobalClass, nullptr,
+                              JS::FireOnNewGlobalHook, options);
+  ASSERT_TRUE(global != nullptr);
+
+  JS::Realm* oldRealm = JS::EnterRealm(cx, global);
+
+  using ElementT = JS::Heap<JSObject*>;
+
+  TestArrayType<nsTArray<ElementT>>(cx);
+  TestArrayType<FallibleTArray<ElementT>>(cx);
+  TestArrayType<AutoTArray<ElementT, 1>>(cx);
+
+  JS::LeaveRealm(cx, oldRealm);
+}
+
+TEST(GCPostBarriers, nsTArray)
+{
+  CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
+  ASSERT_TRUE(ccjscx != nullptr);
+  JSContext* cx = ccjscx->Context();
+  ASSERT_TRUE(cx != nullptr);
+
+  CreateGlobalAndRunTest(cx);
+}