[strong] Implement strong property access semantics

test/mjsunit/strong/load-property-mutate-backing-store.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --strong-mode --allow-natives-syntax
+
+function getSloppyArguments() {
+  return arguments;
+}
+
+function getObjects() {
+  "use strict";
+  return [
+    {},
+    Object(""),
+    [],
+    (function(){}),
+    (class Foo {}),
+    getSloppyArguments(),
+    arguments,
+    new Date(),
+    // TODO(conradw): uncomment once Object.defineProperty is fixed.
+    // new Uint32Array(0)
+  ];
+}
+
+function readFromObjectSloppy(o) {
+    return o.foo;
+}
+
+function readFromObjectKeyedSloppy(o) {
+    return o["foo"];
+}
+
+function readFromObjectKeyedVarSloppy(o) {
+  var a = "foo";
+  return o[a];
+}
+
+function readFromObjectKeyedComputedSloppy(o) {
+  var a = "o";
+  return o["fo" + a];
+}
+
+function readFromObjectStrong(o) {
+  "use strong";
+  return o.foo;
+}
+
+function readFromObjectKeyedStrong(o) {
+  "use strong";
+  return o["foo"];
+}
+
+function readFromObjectKeyedLetStrong(o) {
+  "use strong";
+  let a = "foo";
+  return o[a];
+}
+
+function readFromObjectKeyedComputedStrong(o) {
+  "use strong";
+  let a = "o";
+  return o["fo" + a];
+}
+
+function getDescs(x) {
+  return [
+    {value: x},
+    {configurable: true, enumerable: true, writable: true, value: x},
+    {configurable: true, enumerable: true, get: (function() {return x}) },
+  ];
+}
+
+function assertStrongSemantics(func, object) {
+  %DeoptimizeFunction(func);
+  %ClearFunctionTypeFeedback(func);
+  assertThrows(function(){func(object)}, TypeError);
+  assertThrows(function(){func(object)}, TypeError);
+  assertThrows(function(){func(object)}, TypeError);
+  %OptimizeFunctionOnNextCall(func);
+  assertThrows(function(){func(object)}, TypeError);
+  %DeoptimizeFunction(func);
+  assertThrows(function(){func(object)}, TypeError);
+}
+
+function assertSloppySemantics(func, object) {
+  %DeoptimizeFunction(func);
+  %ClearFunctionTypeFeedback(func);
+  assertDoesNotThrow(function(){func(object)});
+  assertDoesNotThrow(function(){func(object)});
+  assertDoesNotThrow(function(){func(object)});
+  %OptimizeFunctionOnNextCall(func);
+  assertDoesNotThrow(function(){func(object)});
+  %DeoptimizeFunction(func);
+  assertDoesNotThrow(function(){func(object)});
+}
+
+(function () {
+  "use strict";
+
+  let goodKeys = [
+    "foo"
+  ]
+
+  let badKeys = [
+    "bar",
+    "1",
+    "100001",
+    "3000000001",
+    "5000000001"
+  ];
+
+  let values = [
+    "string",
+    1,
+    100001,
+    30000000001,
+    50000000001,
+    NaN,
+    {},
+    undefined
+  ];
+
+  let badAccessorDescs = [
+    { set: (function(){}) },
+    { configurable: true, enumerable: true, set: (function(){}) }
+  ];
+
+  let readSloppy = [
+    readFromObjectSloppy,
+    readFromObjectKeyedSloppy,
+    readFromObjectKeyedVarSloppy,
+    readFromObjectKeyedComputedSloppy
+  ];
+
+  let readStrong = [
+    readFromObjectStrong,
+    readFromObjectKeyedStrong,
+    readFromObjectKeyedLetStrong,
+    readFromObjectKeyedComputedStrong
+  ];
+
+  let dummyProto = {};
+  for (let key of goodKeys) {
+    Object.defineProperty(dummyProto, key, { value: undefined });
+  }
+
+  // After altering the backing store, accessing a missing property should still
+  // throw.
+  for (let key of badKeys) {
+    for (let value of values) {
+      for (let desc of getDescs(value)) {
+        for (let object of getObjects()) {
+          Object.defineProperty(object, key, desc);
+          for (let func of readStrong) {
+            assertStrongSemantics(func, object);
+          }
+          for (let func of readSloppy) {
+            assertSloppySemantics(func, object);
+          }
+          // Accessing a property which is on the prototype chain of the object
+          // should not throw.
+          object.__proto__ = dummyProto;
+          for (let key of goodKeys) {
+            for (let func of readStrong.concat(readSloppy)) {
+              assertSloppySemantics(func, object);
+            }
+          }
+        }
+      }
+    }
+  }
+})();