After experimenting with SUN Forte compiler (forte has an implemented flush to zero option) we have established that gradual underflow seriously hurts the performance of our application. g77 has an optimization option which should turn the gradual underflow off. However, that feature, although announced, was never implemented.
We have tried our luck with the noncommercial version of Intel Fortran Compiler for Linux*, and the following code, when compiled with ifc -ftz or ifc -O3 (which should include -ftz option) returns denormalized number R2.
REAL :: T,R,R2
END PROGRAM underflow
Does this mean that -ftz (flush to zero) is not yet implemented for ifc 7.1 (version of the compiler, we are using) or is this feature not available in the noncommercial version, only?
Thanks in advance for any feedback,