Is there any way to specify to the -fast option to use -xN instead of -xP (this last one is not supported by my processor) ?
You should be able to just specify -xN explicitly on the line after -fast. There is not a way to change the behavior of -fast itself.
This is what I get :(
ifort: Command line warning: -fast overrides any subsequent processor specific option. '-xN' has no effect
Whatever... I will make an 'ifort' alias including the options I usually want.