optimization flags, using openmp

optimization flags, using openmp

Hello,Can someone tell me where to look for the list of optimization flags? I also use openmp so wonder if it conflicts with other flags?At some topic people suggested-O3 -xHost -ipo for ifort v11, my version is 12.0.5. I use these flags and find that they create errors.Lam

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For more complete information about compiler optimizations, see our Optimization Notice.

The only interaction of -openmp with other compile options is that it sets -auto and conflicts with -save. If your program has bugs which appear with -auto or by omission of -save, they surely will appear with -openmp.
Regardless of whether you set -openmp, you may want the options
-assume protect_parens -prec-div -prec-sqrt
or the more conservative -fp-model source, so as to adhere to Fortran and IEEE floating point standards.
If you get errors when you set -openmp, it's more likely that you have threading errors. The compiler does little checking itself, although there is the -diag-enable openmp option to perform some static correctness checking (working together with Inspector, which can also perform run-time parallel consistency checking).

The error I get happens in a serial block, not a parallel one.I have flag -C to check array bounds. The error says the array subscript is 0 which is less than the lower bound of 1. However if I print the subscript out to see if it's really 0, it's printed out non-zero and no error message happens.I found that if I don't use -C I get no error.Lam


I see there was no progress on this thread and like to help you. Would you be able to provide a small reproducer so we can verify the problem you're seeing?

Thank you & best regards,

Georg Zitzlsberger

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