1 files changed, 171 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/cacheir/arguments-iterator-mapped.js b/js/src/jit-test/tests/cacheir/arguments-iterator-mapped.js
new file mode 100644
index 0000000000..0b6024d9af
--- /dev/null
+++ b/js/src/jit-test/tests/cacheir/arguments-iterator-mapped.js
@@ -0,0 +1,171 @@
+// Test iteration with a mapped arguments object.
+
+function simple() {
+  function f() {
+    var sum = 0;
+    for (var v of arguments) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  for (var i = 0; i < 100; ++i) {
+    assertEq(f(1, 2, 3), 6);
+  }
+}
+simple();
+
+function spreadCall() {
+  function f() {
+    var sum = 0;
+    for (var v of arguments) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  function g() {
+    return f(...arguments);
+  }
+
+  for (var i = 0; i < 100; ++i) {
+    assertEq(g(1, 2, 3), 6);
+  }
+}
+spreadCall();
+
+function spreadArray() {
+  function f() {
+    var arr = [...arguments];
+    var sum = 0;
+    for (var v of arr) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  for (var i = 0; i < 100; ++i) {
+    assertEq(f(1, 2, 3), 6);
+  }
+}
+spreadArray();
+
+function reifyIterator() {
+  var reify = false;
+  function f() {
+    if (reify) {
+      // Redefining any property attributes will reify the iterator property.
+      Object.defineProperty(arguments, Symbol.iterator, {
+        writable: false
+      });
+    }
+
+    var sum = 0;
+    for (var v of arguments) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  for (var i = 0; i <= 100; ++i) {
+    reify = i >= 50;
+    assertEq(f(1, 2, 3), 6);
+  }
+}
+reifyIterator();
+
+function overwriteIterator() {
+  var callCount = 0;
+  function Iterator() {
+    callCount += 1;
+    return Array.prototype[Symbol.iterator].call(this);
+  }
+
+  var overwrite = false;
+  function f() {
+    if (overwrite) {
+      arguments[Symbol.iterator] = Iterator;
+    }
+
+    var sum = 0;
+    for (var v of arguments) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  for (var i = 0; i <= 100; ++i) {
+    overwrite = i > 50;
+    assertEq(f(1, 2, 3), 6);
+  }
+  assertEq(callCount, 50);
+}
+overwriteIterator();
+
+function deleteIterator() {
+  var remove = false;
+  function f() {
+    // Deleting Symbol.iterator won't change the shape of the arguments object.
+    // That's why we need to use a separate guard instruction to check if the
+    // iterator property was modified.
+    if (remove) {
+      delete arguments[Symbol.iterator];
+    }
+
+    var sum = 0;
+    for (var v of arguments) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  var error;
+  try {
+    for (var i = 0; i <= 100; ++i) {
+      remove = i === 100;
+      assertEq(f(1, 2, 3), 6);
+    }
+  } catch (e) {
+    error = e;
+  }
+  assertEq(error instanceof TypeError, true);
+}
+deleteIterator();
+
+function deleteIteratorInherit() {
+  var callCount = 0;
+  function Iterator() {
+    callCount += 1;
+    return Array.prototype[Symbol.iterator].call(this);
+  }
+
+  Object.prototype[Symbol.iterator] = Iterator;
+
+  var remove = false;
+  function f() {
+    // Deleting Symbol.iterator won't change the shape of the arguments object.
+    // That's why we need to use a separate guard instruction to check if the
+    // iterator property was modified.
+    if (remove) {
+      delete arguments[Symbol.iterator];
+    }
+
+    var sum = 0;
+    for (var v of arguments) {
+      sum += v;
+    }
+    return sum;
+  }
+
+  for (var i = 0; i <= 100; ++i) {
+    remove = i === 100;
+    assertEq(f(1, 2, 3), 6);
+  }
+  assertEq(callCount, 1);
+
+  delete Object.prototype[Symbol.iterator];
+}
+deleteIteratorInherit();
+
+// Don't add tests below this point because |Object.prototype[Symbol.iterator]|
+// was modified, which may lead to engine-wide deoptimisations.