622 

   623 // Iterating over all nmethods, e.g. with the help of CodeCache::nmethods_do(fun) was found

   624 // to not be inherently safe. There is a chance that fields are seen which are not properly

   625 // initialized. This happens despite the fact that nmethods_do() asserts the CodeCache_lock

   626 // to be held.

   627 // To bundle knowledge about necessary checks in one place, this function was introduced.

   628 // It is not claimed that these checks are sufficient, but they were found to be necessary.

   629 bool CompiledMethod::nmethod_access_is_safe(nmethod* nm) {

   630   Method* method = (nm == NULL) ? NULL : nm->method();  // nm->method() may be uninitialized, i.e. != NULL, but invalid

   631   return (nm != NULL) && (method != NULL) && (method->signature() != NULL) &&

   632          !nm->is_zombie() && !nm->is_not_installed() &&

   633          os::is_readable_pointer(method) &&

   634          os::is_readable_pointer(method->constants()) &&

   635          os::is_readable_pointer(method->signature());

   636 }