1 files changed, 125 insertions, 0 deletions
diff --git a/js/src/jsapi-tests/testGCUniqueId.cpp b/js/src/jsapi-tests/testGCUniqueId.cpp
new file mode 100644
index 0000000000..4ac6e54e76
--- /dev/null
+++ b/js/src/jsapi-tests/testGCUniqueId.cpp
@@ -0,0 +1,125 @@
+/* -*- 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/. */
+
+#include "js/GCVector.h"
+
+#include "jsapi-tests/tests.h"
+
+#include "gc/Zone-inl.h"
+
+static void MinimizeHeap(JSContext* cx) {
+  // The second collection is to force us to wait for the background
+  // sweeping that the first GC started to finish.
+  JS_GC(cx);
+  JS_GC(cx);
+  js::gc::FinishGC(cx);
+}
+
+BEGIN_TEST(testGCUID) {
+#ifdef JS_GC_ZEAL
+  AutoLeaveZeal nozeal(cx);
+#endif /* JS_GC_ZEAL */
+
+  uint64_t uid = 0;
+  uint64_t tmp = 0;
+
+  // Ensure the heap is as minimal as it can get.
+  MinimizeHeap(cx);
+
+  JS::RootedObject obj(cx, JS_NewPlainObject(cx));
+  uintptr_t nurseryAddr = uintptr_t(obj.get());
+  CHECK(obj);
+  CHECK(js::gc::IsInsideNursery(obj));
+
+  // Do not start with an ID.
+  CHECK(!obj->zone()->hasUniqueId(obj));
+
+  // Ensure we can get a new UID.
+  CHECK(obj->zone()->getOrCreateUniqueId(obj, &uid));
+  CHECK(uid > js::gc::LargestTaggedNullCellPointer);
+
+  // We should now have an id.
+  CHECK(obj->zone()->hasUniqueId(obj));
+
+  // Calling again should get us the same thing.
+  CHECK(obj->zone()->getOrCreateUniqueId(obj, &tmp));
+  CHECK(uid == tmp);
+
+  // Tenure the thing and check that the UID moved with it.
+  MinimizeHeap(cx);
+  uintptr_t tenuredAddr = uintptr_t(obj.get());
+  CHECK(tenuredAddr != nurseryAddr);
+  CHECK(!js::gc::IsInsideNursery(obj));
+  CHECK(obj->zone()->hasUniqueId(obj));
+  CHECK(obj->zone()->getOrCreateUniqueId(obj, &tmp));
+  CHECK(uid == tmp);
+
+  // Allocate a new nursery thing in the same location and check that we
+  // removed the prior uid that was attached to the location.
+  obj = JS_NewPlainObject(cx);
+  CHECK(obj);
+  CHECK(uintptr_t(obj.get()) == nurseryAddr);
+  CHECK(!obj->zone()->hasUniqueId(obj));
+
+  // Try to get another tenured object in the same location and check that
+  // the uid was removed correctly.
+  obj = nullptr;
+  MinimizeHeap(cx);
+  obj = JS_NewPlainObject(cx);
+  MinimizeHeap(cx);
+  CHECK(uintptr_t(obj.get()) == tenuredAddr);
+  CHECK(!obj->zone()->hasUniqueId(obj));
+  CHECK(obj->zone()->getOrCreateUniqueId(obj, &tmp));
+  CHECK(uid != tmp);
+  uid = tmp;
+
+  // Allocate a few arenas worth of objects to ensure we get some compaction.
+  const static size_t N = 2049;
+  using ObjectVector = JS::GCVector<JSObject*>;
+  JS::Rooted<ObjectVector> vec(cx, ObjectVector(cx));
+  for (size_t i = 0; i < N; ++i) {
+    obj = JS_NewPlainObject(cx);
+    CHECK(obj);
+    CHECK(vec.append(obj));
+  }
+
+  // Transfer our vector to tenured if it isn't there already.
+  MinimizeHeap(cx);
+
+  // Tear holes in the heap by unrooting the even objects and collecting.
+  JS::Rooted<ObjectVector> vec2(cx, ObjectVector(cx));
+  for (size_t i = 0; i < N; ++i) {
+    if (i % 2 == 1) {
+      CHECK(vec2.append(vec[i]));
+    }
+  }
+  vec.clear();
+
+  // Grab the last object in the vector as our object of interest.
+  obj = vec2.back();
+  CHECK(obj);
+  CHECK(!js::gc::IsInsideNursery(obj));
+  tenuredAddr = uintptr_t(obj.get());
+  CHECK(obj->zone()->getOrCreateUniqueId(obj, &uid));
+
+  // Force a compaction to move the object and check that the uid moved to
+  // the new tenured heap location.
+  JS::PrepareForFullGC(cx);
+  JS::NonIncrementalGC(cx, GC_SHRINK, JS::GCReason::API);
+
+  // There's a very low probability that this check could fail, but it is
+  // possible.  If it becomes an annoying intermittent then we should make
+  // this test more robust by recording IDs of many objects and then checking
+  // that some have moved.
+  CHECK(uintptr_t(obj.get()) != tenuredAddr);
+  CHECK(obj->zone()->hasUniqueId(obj));
+  CHECK(obj->zone()->getOrCreateUniqueId(obj, &tmp));
+  CHECK(uid == tmp);
+
+  return true;
+}
+END_TEST(testGCUID)