Re: [lmi] [lmi-commits] odd/eraseme_error 69d06e9 10/10: Attempt to find a problem

[Greg Chicares]

On 2021-07-07 11:17, Vadim Zeitlin wrote:
> On Wed,  7 Jul 2021 06:22:15 -0400 (EDT) Greg Chicares 
> <gchicares@sbcglobal.net> wrote:
> 
> GC> branch: odd/eraseme_error
[...]
> GC>     Attempt to find a problem
[...]
>  Is this hang reproducible? If so, I could try debugging it.

It's caused by a NaN. I just found that out and was going to
post a message saying you needn't waste your time on it, but
your were quicker than me.

It is reproducible, even with a different version of 'wine'.

>  Generally speaking, the best technique for debugging problems under Wine 
> [...snip...]

That never worked well for me. In this case, I looked back
at the most recent commits and correctly guessed which one
caused the problem. Printing the relevant values on an
implicitly impossible path reveals the NaN infestation:

  if(x < y) foo(); else bar(); // old code that always worked

  if(y <= x) bar(); else foo(); // failing replacement

  // altered replacement that exposes NaNs:
  if(y <= x)
    bar()
  else if(x < y)
    foo()
  else // "impossible", modulo NaN
    print_values_to_detect_NaNs(); // NaNs detected!