B.5  Version 4.0 to 4.5 Differences

• Support for several features of Fortran 2003 was added (see Section 1.7).
• The if clause was extended to take a directive-name-modifier that allows it to apply to combined constructs (see Section 3.4).
• The implicit data-sharing attribute for scalar variables in target regions was changed to firstprivate (see Section 5.1.1).
• Use of some C++ reference types was allowed in some data sharing attribute clauses (see Section 5.4).
• The ref, val, and uval modifiers were added to the linear clause (see Section 5.4.6).
• Semantics for reductions on C/C++ array sections were added and restrictions on the use of arrays and pointers in reductions were removed (see Section 5.5.8).
• Support was added to the map clauses to handle structure elements (see Section 5.8.3).
• To support unstructured data mapping for devices, the map clause (see Section 5.8.3) was updated and the target enter data (see Section 13.6) and target exit data (see Section 13.7) constructs were added.
• The declare target directive was extended to allow mapping of global variables to be deferred to specific device executions and to allow an extended-list to be specified in C/C++ (see Section 7.8).
• The simdlen clause was added to the simd construct (see Section 10.4) to support specification of the exact number of iterations desired per SIMD chunk.
• A parameter was added to the ordered clause of the worksharing-loop construct (see Section 11.5) and clauses were added to the ordered construct (see Section 15.10) to support doacross loop nests and use of the simd construct on loops with loop-carried backward dependences.
• The linear clause was added to the worksharing-loop construct (see Section 11.5).
• The priority clause was added to the task construct (see Section 12.5) to support hints that specify the relative execution priority of explicit tasks. The omp_get_max_task_priority routine was added to return the maximum supported priority value (see Section 18.5.1) and the OMP_MAX_TASK_PRIORITY environment variable was added to control the maximum priority value allowed (see Section 21.2.9).
• The taskloop construct (see Section 12.6) was added to support nestable parallel loops that create OpenMP tasks.
• To support interaction with native device implementations, the use_device_ptr clause was added to the target data construct (see Section 13.5) and the is_device_ptr clause was added to the target construct (see Section 13.8).
• The nowait and depend clauses were added to the target construct (see Section 13.8) to improve support for asynchronous execution of target regions.
• The private, firstprivate and defaultmap clauses were added to the target construct (see Section 13.8).
• The hint clause was added to the critical construct (see Section 15.2).
• The source and sink dependence types were added to the depend clause (see Section 15.9.5) to support doacross loop nests.
• To support a more complete set of device construct shortcuts, the target parallel, target parallel worksharing-loop, target parallel worksharing-loop SIMD, and target simd (see Section 17.3) combined constructs were added.
• Query functions for OpenMP thread affinity were added (see Section 18.3.2 to Section 18.3.7).
• Device memory routines were added to allow explicit allocation, deallocation, memory transfers, and memory associations (see Section 18.8).
• The lock API was extended with lock routines that support storing a hint with a lock to select a desired lock implementation for a lock’s intended usage by the application code (see Section 18.9.2).
• C/C++ Grammar (previously Appendix B) was moved to a separate document.