v8/test/mjsunit/elide-double-hole-check-1.js

// Copyright 2013 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 f1(a, i) {
  return a[i]
}

var a1 = [,,,,,,,,,,,,,,,,,,0.5];
%PrepareFunctionForOptimization(f1);
assertEquals(undefined, f1(a1, 1));
assertEquals(undefined, f1(a1, 1));
%OptimizeFunctionOnNextCall(f1);
assertEquals(undefined, f1(a1, 1));
assertEquals(undefined, f1(a1, 1));

function f2(a, i) {
  return a[i] + 0.5;
}
var a2_b = [0.0,,];
%PrepareFunctionForOptimization(f2);
assertEquals(0.5, f2(a2_b, 0));
assertEquals(0.5, f2(a2_b, 0));
%OptimizeFunctionOnNextCall(f2);
assertEquals(0.5, f2(a2_b, 0));
assertEquals(NaN, f2(a2_b, 1));
a2_b.__proto__ = [1.5,1.5,1.5];
assertEquals(2, f2(a2_b, 1));
assertEquals(0.5, f2(a2_b, 0));