This is the mail archive of the
`fortran@gcc.gnu.org`
mailing list for the GNU Fortran project.

Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|

Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |

Other format: | [Raw text] |

*From*: Tim Prince <n8tm at aol dot com>*To*: fortran at gcc dot gnu dot org*Date*: Thu, 30 Jun 2011 18:34:00 -0400*Subject*: Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math*References*: <4E0B8B0C.4020105@noaa.gov> <20110629210237.GA12888@troutmask.apl.washington.edu> <4E0CCFBB.9010003@noaa.gov> <201106302213.37976.franke.daniel@gmail.com> <20110630212039.GA19729@troutmask.apl.washington.edu>*Reply-to*: tprince at computer dot org

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.

-fnocx-limited-range -fnoreciprocal-math have been commonly desired ways to back off from -ffast-math. Have these options changed, or did I get the spelling wrong?

Is -mreciprocal implied by -ffinite-math-only? This seems to involve some disconnect; one of the reasons for avoiding -mreciprocal being to avoid premature violation of the conditions for finite-math-only.

-- Tim Prince

**References**:**SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math***From:*Paul van Delst

**Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math***From:*Steve Kargl

**Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math***From:*Paul van Delst

**Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math***From:*Daniel Franke

**Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math***From:*Steve Kargl

Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|

Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |