question on the classFileParser logic

[Ivan Krylov]

Hi,

I have a following question on the code in the classFileParser.
I am looking at the jdk9 hotspot, but the same was in 8 and 7.


The following comment suggests that by this point vtable may not be initialized and hence we are placing NULL into vtable:

klassVtable.cpp:239

    // In class hierarchies where the accessibility is not increasing (i.e., going from private ->
    // package_private -> public/protected), the vtable might actually be smaller than our initial
    // calculation.
    assert(initialized <= _length, "vtable initialization failed");
    for(;initialized < _length; initialized++) {
      put_method_at(NULL, initialized);
    }

This is the put method: some diagnostic prints and a set method at the end.

klassVtable.cpp:509
void klassVtable::put_method_at(Method* m, int index) {
#ifndef PRODUCT
  if (PrintVtables && Verbose) {
    ResourceMark rm;
    const char* sig = (m != NULL) ? m->name_and_sig_as_C_string() : "<NULL>";
    tty->print("adding %s at index %d, flags: ", sig, index);
    if (m != NULL) {
      m->access_flags().print_on(tty);
      if (m->is_default_method()) {
        tty->print("default ");
      }
      if (m->is_overpass()) {
        tty->print("overpass");
      }
    }
    tty->cr();
  }
#endif
  table()[index].set(m);
}

Now the set method will assert on the NULL reference.

klassVtable.hpp:170
  void set(Method* method)  { assert(method != NULL, “use clear"); _method = method; }

My question is about the for loop above, how is this suppose to work if initialised < _length?
Should the assert above simply be like this: assert(initialised == _length, “vtable initialisation failed”) ?

Thanks,

Ivan