Bare minimum -Og/-O0 -O0 basically tells the compiler to make no optimisations. Optimiser can remove some local variables, merge some code blocks, etc. and as an outcome it can make debugging unpredictable. The price for -O0 option is very slow code execution, but starting from version 4.8 GCC compilers (including the Fortran one) accept a … Read more
Bare minimum -Og/-O0 -O0 basically tells the compiler to make no optimisations. Optimiser can remove some local variables, merge some code blocks, etc. and as an outcome it can make debugging unpredictable. The price for -O0 option is very slow code execution, but starting from version 4.8 GCC compilers (including the Fortran one) accept a … Read more
With gcc, you need to compile and link with -fopenmp to enable OpenMP. Other compilers have different options; with intel it’s -openmp, with pgi it’s -mp, etc.