1 files changed, 122 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/gc/weakRefs.js b/js/src/jit-test/tests/gc/weakRefs.js
new file mode 100644
index 0000000000..e052aa779b
--- /dev/null
+++ b/js/src/jit-test/tests/gc/weakRefs.js
@@ -0,0 +1,122 @@
+// https://tc39.es/ecma262/#sec-addtokeptobjects
+// When the abstract operation AddToKeptObjects is called with a target object
+// reference, it adds the target to an identity Set that will point strongly at
+// the target until the end of the current Job.
+//
+// https://tc39.es/proposal-weakrefs/#sec-weakref-invariants
+// When WeakRef.prototype.deref is called, the referent (if it's not already
+// dead) is kept alive so that subsequent, synchronous accesses also return the
+// object.
+
+function testSameCompartmentWeakRef(
+  targetReachable,
+  weakRefReachable) {
+
+  let target = {};
+
+  let weakref = new WeakRef(target);
+  assertEq(weakref.deref(), target);
+
+  if (!targetReachable) {
+    target = undefined;
+  }
+
+  if (!weakRefReachable) {
+    weakRef = undefined;
+  }
+
+  clearKeptObjects();
+  gc();
+
+  if (weakRefReachable) {
+    if (targetReachable) {
+      assertEq(weakref.deref(), target);
+    } else {
+      assertEq(weakref.deref(), undefined);
+    }
+  }
+}
+
+let serial = 0;
+
+function testCrossCompartmentWeakRef(
+  targetReachable,
+  weakRefReachable,
+  collectTargetZone,
+  collectWeakRefZone,
+  sameZone) {
+
+  gc();
+
+  let id = serial++;
+  let global = newGlobal(sameZone ? {sameZoneAs: this} : {newCompartment: true});
+  global.eval('var target = {};');
+  global.target.id = id;
+
+  let weakref = new WeakRef(global.target);
+  assertEq(weakref.deref(), global.target);
+
+  if (!targetReachable) {
+    global.target = undefined;
+  }
+
+  if (!weakRefReachable) {
+    weakRef = undefined;
+  }
+
+  if (collectTargetZone || collectWeakRefZone) {
+    clearKeptObjects();
+
+    if (collectTargetZone) {
+      schedulezone(global);
+    }
+    if (collectWeakRefZone) {
+      schedulezone(this);
+    }
+
+    // Incremental GC so we use sweep groups. Shrinking GC to test updating
+    // pointers.
+    startgc(1, 'shrinking');
+    while (gcstate() !== 'NotActive') {
+      gcslice(1000, {dontStart: true});
+    }
+  }
+
+  if (!(collectWeakRefZone && !weakRefReachable)) {
+    if (collectTargetZone && !targetReachable) {
+      assertEq(weakref.deref(), undefined);
+    } else if (targetReachable) {
+      assertEq(weakref.deref(), global.target);
+    } else {
+      // Target is not strongly reachable but hasn't been collected yet. We
+      // can get it back through deref() but must check it based on properties.
+      assertEq(weakref.deref() !== undefined, true);
+      assertEq(weakref.deref().id, id);
+    }
+  }
+}
+
+gczeal(0);
+
+for (let targetReachable of [true, false]) {
+  for (let weakRefReachable of [true, false]) {
+    testSameCompartmentWeakRef(targetReachable, weakRefReachable);
+  }
+}
+
+for (let targetReachable of [true, false]) {
+  for (let weakRefReachable of [true, false]) {
+    for (let collectTargetZone of [true, false]) {
+      for (let collectWeakRefZone of [true, false]) {
+        for (let sameZone of [true, false]) {
+          if (sameZone && (collectTargetZone != collectWeakRefZone)) {
+            continue;
+          }
+
+          testCrossCompartmentWeakRef(targetReachable, weakRefReachable,
+                                      collectTargetZone, collectWeakRefZone, sameZone);
+        }
+      }
+    }
+  }
+}