third_party/v8/test/mjsunit/regress/regress-961709-classes-opt.js

// Copyright 2019 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: --allow-natives-syntax --opt --no-always-opt

function foo(a, i) {
  a[i] = 1;
  return a[i];
}

class MyArray extends (class C extends Array {
}){};

o = new MyArray;

%PrepareFunctionForOptimization(foo);
assertEquals(1, foo(o, 0));
assertEquals(1, foo(o, 1));
%OptimizeFunctionOnNextCall(foo);
assertEquals(1, foo(o, 2));
assertOptimized(foo);

// Change prototype
o.__proto__.__proto__ = new Int32Array(3);


// Check it still works
assertEquals(undefined, foo(o, 3));
assertUnoptimized(foo);
%PrepareFunctionForOptimization(foo);
assertEquals(undefined, foo(o, 3));
%OptimizeFunctionOnNextCall(foo);
assertEquals(undefined, foo(o, 3));