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Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math
- From: dominiq at lps dot ens dot fr (Dominique Dhumieres)
- To: fortran at gcc dot gnu dot org
- Cc: Paul dot Vandelst at noaa dot gov
- Date: Sat, 02 Jul 2011 14:36:21 +0200
- Subject: Re: SIGFPE, Arithmetic exception. "Value optimized out" when using --ffast-math
Paul,
> Trying the options one-by-one, it was the -funsafe-math-optimizations
> option that caused the program to crash using gfortran 4.4.4.
Could you try
-O3 -funsafe-math-optimizations -ffinite-math-only -fno-reciprocal-math
and
-O3 -funsafe-math-optimizations -ffinite-math-only -fno-tree-vectorize
?
What you describe reminds me pr43716
( http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43716 ).
This pr appeared and disappeared without convincing explanation
and could be a rampant bug exposed by your code. Does it contain
constructs such as the one in comment #13?
> I guess just the name of that option should raise a red flag, hey? :o)
I am not sure that the name has been well chosen. I rather think
that code that are not surviving associative-math or reciprocal-math
are themselves unsafe.
Cheers,
Dominique