[strong] Implement strong mode restrictions on property access

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

Index: test/mjsunit/strong/load-element-mutate-backing-store.js
diff --git a/test/mjsunit/strong/load-element-mutate-backing-store.js b/test/mjsunit/strong/load-element-mutate-backing-store.js
new file mode 100644
index 0000000000000000000000000000000000000000..d6cccdbd5b3e48616e7c57ec3ab64ccd49b87564
--- /dev/null
+++ b/test/mjsunit/strong/load-element-mutate-backing-store.js
@@ -0,0 +1,220 @@
+// 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
+
+// TODO(conradw): Track implementation of strong bit for other objects, add

[rossberg, 2015/06/10 08:28:08]

See above

[conradw, 2015/06/10 12:03:22]

Done.

+// tests.
+
+function getObjects() {

[rossberg, 2015/06/10 08:28:08]

See above

[conradw, 2015/06/10 12:03:23]

Done.

+  "use strict";
+  return [
+    {},
+    [],
+    (function(){}),
+    (class Foo {})
+  ];
+}
+
+function readFromObjectElementSloppy(o) {
+  return o[0];
+}
+
+function readFromObjectElementSparseSloppy(o) {
+  return o[100000];
+}
+
+function readFromObjectElementNonSmiSloppy(o) {
+  return o[3000000000];
+}
+
+function readFromObjectNonIndexSloppy(o) {
+  return o[5000000000];
+}
+
+function readFromObjectElementVarSloppy(o) {
+  var a = 0;
+  return o[a];
+}
+
+function readFromObjectElementSparseVarSloppy(o) {
+  var a = 100000;
+  return o[a];
+}
+
+function readFromObjectElementNonSmiVarSloppy(o) {
+  var a = 3000000000;
+  return o[a];
+}
+
+function readFromObjectNonIndexVarSloppy(o) {
+  var a = 5000000000;
+  return o[a];
+}
+
+function readFromObjectElementStrong(o) {
+  "use strong";
+  return o[0];
+}
+
+function readFromObjectElementSparseStrong(o) {
+  "use strong";
+  return o[100000];
+}
+
+function readFromObjectElementNonSmiStrong(o) {
+  "use strong";
+  return o[3000000000];
+}
+
+function readFromObjectNonIndexStrong(o) {
+  "use strong";
+  return o[5000000000];
+}
+
+function readFromObjectElementLetStrong(o) {
+  "use strong";
+  let a = 0;
+  return o[a];
+}
+
+function readFromObjectElementSparseLetStrong(o) {
+  "use strong";
+  let a = 100000;
+  return o[a];
+}
+
+function readFromObjectElementNonSmiLetStrong(o) {
+  "use strong";
+  let a = 3000000000;
+  return o[a];
+}
+
+function readFromObjectNonIndexLetStrong(o) {
+  "use strong";
+  let a = 5000000000;
+  return o[a];
+}
+
+function getDescs(x) {
+  return [
+    {value: x},
+    {configurable: true, 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 = [
+    "0",
+    "100000",
+    "3000000000",
+    "5000000000"
+  ]
+
+  let badKeys = [
+    "bar",
+    "1",
+    "100001",
+    "3000000001",
+    "5000000001"
+  ];
+
+  let values = [
+    "string",
+    1,
+    100001,
+    30000000001,
+    50000000001,
+    NaN,
+    {},
+    undefined
+  ];
+
+  let badAccessorDescs = [
+    { set: (function(){}) },
+    { configurable: true, set: (function(){}) },
+    { configurable: true, enumerable: true, set: (function(){}) }
+  ];
+
+  let readSloppy = [
+    readFromObjectElementSloppy,
+    readFromObjectElementSparseSloppy,
+    readFromObjectElementNonSmiSloppy,
+    readFromObjectNonIndexSloppy,
+    readFromObjectElementVarSloppy,
+    readFromObjectElementSparseVarSloppy,
+    readFromObjectElementNonSmiVarSloppy,
+    readFromObjectNonIndexVarSloppy
+  ];
+
+  let readStrong = [
+    readFromObjectElementStrong,
+    readFromObjectElementSparseStrong,
+    readFromObjectElementNonSmiStrong,
+    readFromObjectNonIndexStrong,
+    readFromObjectElementLetStrong,
+    readFromObjectElementSparseLetStrong,
+    readFromObjectElementNonSmiLetStrong,
+    readFromObjectNonIndexLetStrong
+  ];
+
+  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) {

[rossberg, 2015/06/10 08:28:08]

Yeah, a quintuple loop like this is probably producing quite a long-running
test. Maybe you don't need to test the full matrix, but just vary a few of the
dimensions at a time?

[conradw, 2015/06/10 12:03:23]

On reflection, I may have overstated how bad the test run times are. With the
current splitting, they take comfortably less than half (worst case) the time of
the longest running mjsunit test.

+            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);
+            }
+          }
+        }
+      }
+    }
+  }
+})();