v8/test/mjsunit/regress/regress-load-elements.js

// Copyright 2012 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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// Flags: --allow-natives-syntax

function bad_func(o, a) {
  for (var i = 0; i < 1; ++i) {
    o.prop = 0;
    var x = a[0];
  }
};
%PrepareFunctionForOptimization(bad_func);
o = new Object();
a = {};
a[0] = 1;
bad_func(o, a);

o = new Object();
bad_func(o, a);

// Optimize. Before the fix, the elements-load and subsequent fixed-array-length
// were hoisted above the map check. This is invalid since not all types
// necessarily have elements.
%OptimizeFunctionOnNextCall(bad_func);
bad_func(o, "");