test/mjsunit/elide-double-hole-check-9.js

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//
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// Flags: --allow-natives-syntax

var do_set = false;

%NeverOptimizeFunction(set_proto_elements);
function set_proto_elements() {
  if (do_set) Array.prototype[1] = 1.5;
}

function f(a, i) {
  set_proto_elements();
  return a[i] + 0.5;
}

var arr = [0.0,,2.5];
assertEquals(0.5, f(arr, 0));
assertEquals(0.5, f(arr, 0));
%OptimizeFunctionOnNextCall(f);
assertEquals(0.5, f(arr, 0));
do_set = true;
assertEquals(2, f(arr, 1));