Regarding -acc flag on pgfortran

Is the -acc flag only for OpenACC, OR does it do other optimizations also?

I am asking because,

  • when i compile (and run) my program using pgfortran, I am getting some timing.
  • when i compile (and run) the same program using pgfortran -acc, I am seeing faster execution time. Note: there are NO OpenACC blocks yet.

Kindly confirm.


Hi Arun,

“-O2” is implied by -acc since -O2 adds loop dependency analysis that’s needed for OpenACC.


This explains the reduction in execution-time.