PGI Fortran Reference manual - The Portland Group

OpenMP Directives for FortranClausesUsagePRIVATE(list)FIRSTPRIVATE(list)COPYPRIVATE(list)In a parallel region of code, there may be a sub-region of code that only executes correctly on asingle thread. Instead of ending the parallel region before this subregion and then starting it upagain after this subregion, the SINGLE...END SINGLE directive pair or the omp single pragmalets you conveniently designate code that executes on a single thread and is skipped by the otherthreads.The following restrictions apply to the SINGLE...END SINGLE directive:‣ There is an implied barrier on exit from a SINGLE...END SINGLE section of code unlessthe optional NOWAIT clause is specified.‣ Nested single process sections are ignored.‣ Branching into or out of a single process section is not supported.ExamplesPROGRAM SINGLE_USEINTEGER A(0:1)INTEGER omp_get_thread_num()!$OMP PARALLELA(omp_get_thread_num()) = omp_get_thread_num()!$OMP SINGLEPRINT *, "YOU SHOULD ONLY SEE THIS ONCE"!$OMP END SINGLE!$OMP END PARALLELPRINT *, "A(0)=",A(0), " A(1)=", A(1)END8.7.15. TASKThe OpenMP TASK directive defines an explicit task.Syntax!$OMP TASK [Clauses]< Fortran code executed as task >!$OMP END TASKClausesIF(scalar_logical_expression)UNTIEDDEFAULT(private | firstprivate | shared | none)PRIVATE(list)FIRSTPRIVATE(list)SHARED(list)PGI Fortran Reference Guide 176