Calculation differences between Debug and Release mode

[Marco Leise]

Am Mon, 15 Apr 2013 11:51:43 -0400
schrieb "Steven Schveighoffer" <schveiguy at yahoo.com>:

> On Mon, 15 Apr 2013 11:51:07 -0400, Steven Schveighoffer  
> <schveiguy at yahoo.com> wrote:
> 
> > I would suspect that the issue is floating point error.  On certain  
> > hardware, the CPU uses higher-precision 80-bit floating points.  When  
> > you store those back to doubles, the extra precision is truncated.
> 
> I see you use float not double, but the point is still valid.
> 
> -Steve

What worries me is that this jeopardizes the efforts put into
C to make floating point calculations the same under all
circumstances. GCC for example has the fast-math switch if you
really want just the fastest way to get a result, but
otherwise follows strict evaluation and assignment order of
floating point math even in const-folding, so situations like
these don't occur.
I completely agree with your explanation why it happens and I
think it is a bug that must be reported to the respective
compiler developers.

-- 
Marco