Digital AXP notes
=================

- longjmp() restores registers by following up the call stack so the
  restored register set is the last active one in the function that
  contains the setjmp (this is different than Intel where it is the
  register set when the setjmp executed)
  
  - long term: we should fix our longjmp to behave like the Intel
    longjmp in all circumstances since we have potential problems
    with optimizations that don't "know" about the behaviour of
    setjmp/longjmp
  
- the stack unwinding process cannot execute properly if a breakpoint
  occurs in the prologue or epilogue code (always set breakpoints
  after the prologue)
