Re: Optimized gcc 4.3.0 build on Windows returns 0 secs for all time values of system-process-attributes

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 3 Jan 2009 14:53:25 +0100
> From: "Juanma Barranquero" <lekktu@gmail.com>
> Cc: emacs-devel@gnu.org
> 
> On Sat, Jan 3, 2009 at 14:28, Juanma Barranquero <lekktu@gmail.com> wrote:
> 
> >> Could you please show the values of ft_kernel, stime_sec, and
> >> stime_usec after the last of the above 3 lines, namely after
> >>
> >>  stime_sec = tem1 * 0.000001L;
> >>
> >> ?
> 
> Hmm.
> 
> The inlined code that implements the fmodl() call seems to be modifying tem1;
> doing
> 
>   snprintf (buf, sizeof (buf), "tem1 (1) = %Lf\n", tem1);
> OutputDebugString (buf);
>   stime_usec = fmodl (tem1, 1000000.0L);
>   snprintf (buf, sizeof (buf), "tem1 (2) = %Lf\n", tem1);
> OutputDebugString (buf);
> 
> I get the following results:
> 
> tem1 (1) = 82703125.000000
> tem1 (2) = 703125.000000

That's a bug in GCC, I'd say: all these variables are in registers, so
it probably reuses one of the FP registers incorrectly.

What happens if you transpose these two lines:

  stime_usec = fmodl (tem1, 1000000.0L);
  stime_sec = tem1 * 0.000001L;

(and similarly for other ?time_* qualities)? does the code work again
then?  (Note that I reuse tem1 and tem2 twice in the code, so even if
transposition works, something else will need to be done to make all
of the function work correctly.)