v8/test/mjsunit/regress/regress-crbug-642056.js

// Copyright 2016 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

function f(o) {
  return o.x instanceof Array;
};
%PrepareFunctionForOptimization(f);
var o = {x: 1.5};
o.x = 0;

f(o);
f(o);
%OptimizeFunctionOnNextCall(f);
f(o);