[Python-Dev] Is core dump always a bug? Advice requested

Greg Ewing greg at cosc.canterbury.ac.nz
Tue May 11 23:27:29 EDT 2004


"Fred L. Drake, Jr." <fdrake at acm.org>:

> I don't see any reason to think them equivalent; we don't need to determine 
> that the code will execute to completion, only that the bytecodes can be 
> decoded without error.

If arbitrary branching patterns are allowed, then in order to ensure
absence of stack overflow/underflow, etc., it will be necessary to do
things like proving that certain loops can't execute more than a
certain number of times. This smells halting-problem-complete to me.

It would be possible to prove that certain classes of bytecode
sequence are valid, and reject all others. But I suspect that would
reject a large number of valid-but-hard-to-prove sequences that
bytecode hackers would find "interesting".

Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | A citizen of NewZealandCorp, a	  |
Christchurch, New Zealand	   | wholly-owned subsidiary of USA Inc.  |
greg at cosc.canterbury.ac.nz	   +--------------------------------------+



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