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Re: GCC 3.4.4
Fritz Jost writes:
>
> I have come across an issue using GCC 3.4.4 which I am in need of
> help. The problem manifests itself as extremely slow floating point
> performance for specific arguments passed to the dsin function in
> FORTRAN using g77. The following statement :
>
> y = dsin(dble(1.25169754E-06))
>
> when compiled with g77 under GCC 3.4.4 will take 400usec to execute
> on my 2+ GHz Opteron platform. I have tested several machines and
> they all show the same problem. The same code executes at sub
> microsecond speed using GCC 4.0.2 on a Turion-64 notebook as well
> as a XEON based machine using gcc 3.3.3. Unfortunately changing the
> GCC version on my project is not an option. Can anybody shed some
> light on what is going on here ?
Please see http://gcc.gnu.org/ml/gcc-help/2006-05/msg00189.html
That question is about pow() rather than sin(). but the answer is the
same.
See also __dubsin() in glibc/sysdeps/ieee754/dbl-64/dsincos.c.
Andrew.