Optimize Object.seal and Object.preventExtensions

test/mjsunit/object-seal.js

 // Copyright 2010 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
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 249 matching lines @@
 obj = [1,2,3];
 Object.seal(obj);
 assertDoesNotThrow(function() { obj.splice(0,1,100); });
 assertEquals(100, obj[0]);
 assertDoesNotThrow(function() { obj.splice(0,2,1,2); });
 assertDoesNotThrow(function() { obj.splice(1,2,1,2); });
 // Count of items to delete is clamped by length.
 assertDoesNotThrow(function() { obj.splice(1,2000,1,2); });
 assertThrows(function() { obj.splice(0,0,1); }, TypeError);
 assertThrows(function() { obj.splice(1,2000,1,2,3); }, TypeError);
+
+// Test that the enumerable attribute is unperturbed by sealing.
+obj = { x: 42, y: 'foo' };
+Object.defineProperty(obj, 'y', {enumerable: false});
+Object.seal(obj);
+assertTrue(Object.isSealed(obj));
+assertFalse(Object.isFrozen(obj));
+desc = Object.getOwnPropertyDescriptor(obj, 'x');
+assertTrue(desc.enumerable);
+desc = Object.getOwnPropertyDescriptor(obj, 'y');
+assertFalse(desc.enumerable);
+
+// Fast properties should remain fast
+obj = { x: 42, y: 'foo' };
+assertTrue(%HasFastProperties(obj));
+Object.seal(obj);
+assertTrue(Object.isSealed(obj));
+assertFalse(Object.isFrozen(obj));
+assertTrue(%HasFastProperties(obj));
+
+// Sealed objects should share maps where possible
+obj = { prop1: 1, prop2: 2 };
+obj2 = { prop1: 3, prop2: 4 };
+assertTrue(%HaveSameMap(obj, obj2));
+Object.seal(obj);
+Object.seal(obj2);
+assertTrue(Object.isSealed(obj));
+assertTrue(Object.isSealed(obj2));
+assertFalse(Object.isFrozen(obj));
+assertFalse(Object.isFrozen(obj2));
+assertTrue(%HaveSameMap(obj, obj2));
+
+// Sealed objects should share maps even when they have elements
+obj = { prop1: 1, prop2: 2, 75: 'foo' };
+obj2 = { prop1: 3, prop2: 4, 150: 'bar' };
+assertTrue(%HaveSameMap(obj, obj2));
+Object.seal(obj);
+Object.seal(obj2);
+assertTrue(Object.isSealed(obj));
+assertTrue(Object.isSealed(obj2));
+assertFalse(Object.isFrozen(obj));
+assertFalse(Object.isFrozen(obj));
+assertTrue(%HaveSameMap(obj, obj2));
+
+// Setting elements after sealing should not be allowed
+obj = { prop: 'thing' };
+Object.seal(obj);
+assertTrue(Object.isSealed(obj));
+assertFalse(Object.isFrozen(obj));
+obj[0] = 'hello';
+assertFalse(obj.hasOwnProperty(0));
+
+// Sealing an object in dictionary mode should work
+// Also testing that getter/setter properties work after sealing
+obj = { };
+for (var i = 0; i < 100; ++i) {
+  obj['x' + i] = i;
+}
+var accessorDidRun = false;
+Object.defineProperty(obj, 'accessor', {
+  get: function() { return 42 },
+  set: function() { accessorDidRun = true },
+  configurable: true,
+  enumerable: true
+});
+
+assertFalse(%HasFastProperties(obj));
+Object.seal(obj);
+assertFalse(%HasFastProperties(obj));
+assertTrue(Object.isSealed(obj));
+assertFalse(Object.isFrozen(obj));
+assertFalse(Object.isExtensible(obj));
+for (var i = 0; i < 100; ++i) {
+  desc = Object.getOwnPropertyDescriptor(obj, 'x' + i);
+  assertFalse(desc.configurable);
+}
+assertEquals(42, obj.accessor);
+assertFalse(accessorDidRun);
+obj.accessor = 'ignored value';
+assertTrue(accessorDidRun);
+
+// Sealing arguments should work
+var func = function(arg) {
+  Object.seal(arguments);
+  assertTrue(Object.isSealed(arguments));
+};
+func('hello', 'world');
+func('goodbye', 'world');
+
+// Sealing sparse arrays
+var sparseArr = [0, 1];
+sparseArr[10000] = 10000;
+Object.seal(sparseArr);
+assertTrue(Object.isSealed(sparseArr));
+
+// Accessors on fast object should behavior properly after sealing
+obj = {};
+Object.defineProperty(obj, 'accessor', {
+  get: function() { return 42 },
+  set: function() { accessorDidRun = true },
+  configurable: true,
+  enumerable: true
+});
+assertTrue(%HasFastProperties(obj));
+Object.seal(obj);
+assertTrue(Object.isSealed(obj));
+assertTrue(%HasFastProperties(obj));
+assertEquals(42, obj.accessor);
+accessorDidRun = false;
+obj.accessor = 'ignored value';
+assertTrue(accessorDidRun);
+
+// Test for regression in mixed accessor/data property objects.
+// The strict function is one such object.
+assertTrue(Object.isSealed(Object.seal(function(){"use strict";})));
+
+// Also test a simpler case
+obj = {};
+Object.defineProperty(obj, 'accessor2', {
+  get: function() { return 42 },
+  set: function() { accessorDidRun = true },
+  configurable: true,
+  enumerable: true
+});
+obj.data = 'foo';
+assertTrue(%HasFastProperties(obj));
+Object.seal(obj);
+assertTrue(%HasFastProperties(obj));
+assertTrue(Object.isSealed(obj));