Bug in PositiveTableConstraint::InitialPropagate

[orwant]

Originally reported on Google Code with ID 6

On some instances, there is an assertion failure when PositiveTableConstraint::InitialPropagate
calls IntervalUp64.

You pass position+1 as argument, but position can have any value between 0 and 63.
If it is 63, then you call IntervalUp64(64) which leads to the assertion failure.

If you run the program with NDEBUG, this leads to an infinite loop.

The trivial solution would be to add a check, but maybe there's something smarter that
can be done.

Reported by phil.vank on 2011-09-16 05:55:00

[orwant]

From what I understand from the code you could write it like this, solving the problem
and making it faster :

virtual void InitialPropagate() {
  // Build active_ structure.
  for (int var_index = 0; var_index < arity_; ++var_index) {
    for (ConstIter<hash_map<int64, uint64*> > it(masks_[var_index]); !it.at_end();
++it) {
      if (!vars_[var_index]->Contains(it->first)) {
        for (int i = 0; i < length_; ++i) {
          active_tuples_[i] &= ~(active_tuples_[i] & it->second[i]);
        }
      }
    }
  }
  (...)
}

Reported by phil.vank on 2011-09-16 06:17:20

[orwant]

I will have a look right away.
Thanks for the bug report.

Reported by laurent.perron on 2011-09-17 08:26:00

[orwant]

I have added you suggestion and cleaned up the code around.
Thanks!

Reported by laurent.perron on 2011-09-17 08:49:00

• Status changed: Fixed