difference in calculation result when using gcc vs Visual studio and optimisation flag

[Mason]

On 25/04/2018 13:27, Игорь Сотниченко wrote:

> Hello!
> 
> 1. There is a decent difference between calculations on Visual studio
> compiler and gcc 7.1 in  calculation result of my program.

Floating point or integer computation?

Getting identical FP results on different platforms is a chimera.

> 2.       When optimization in gcc  are disabled, then there is no
> difference.
> 
> 3.       When I have replaced O2 with keys from O1 and O2 (
> https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html), then there is no
> difference in results, but there is a calculation speed degradation
> compared to O2.

It is easier to discuss code when actual code is provided ;-)

Regards.