deps/v8/src/js/harmony-atomics.js
function AtomicsCompareExchangeJS(sta, index, oldValue, newValue) {
  CheckSharedIntegerTypedArray(sta);
  index = ValidateIndex(index, %_TypedArrayGetLength(sta));
  oldValue = TO_NUMBER(oldValue);
  newValue = TO_NUMBER(newValue);
  return %_AtomicsCompareExchange(sta, index, oldValue, newValue);
}
function AtomicsCompareExchangeJS(sta, index, oldValue, newValue) {
  CheckSharedIntegerTypedArray(sta);
  index = ValidateIndex(index, %_TypedArrayGetLength(sta));
  oldValue = TO_NUMBER(oldValue);
  newValue = TO_NUMBER(newValue);
  return %_AtomicsCompareExchange(sta, index, oldValue, newValue);
}
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