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Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math
On Thu, Jun 30, 2011 at 10:13:37PM +0200, Daniel Franke wrote:
> On Thursday 30 June 2011 21:34:19 Paul van Delst wrote:
> > Is there any other investigative work you could recommend I do to find the
> > root cause of the exception?
>
> Hi Paul.
>
> Besides a self contained testcase for everyone to check, depending on your
> patience it might help to identify the exact offender; -ffast-math simply
> enables a bunch of potentially unsafe options [1]:
>
> -ffast-math
> Sets -fno-math-errno, -funsafe-math-optimizations,
> -fno-trapping-math, -ffinite-math-only, -fno-rounding-math,
> -fno-signaling-nans and fcx-limited-range.
>
> Try the options individually, all but one, other groups if required.
> Identifying the bad one might give a clue?!
>
At one time, the above set of options was not equivalent to
-ffast-math. Don't know if this is still true, but it should
be easy to test by compiling a moderately complicate program
and comparing the results *.o and final executables.
--
Steve