This page contains information on GCC's implementation of the OpenMP specification and related functionality like the auto parallelizer (-ftree-parallelize-loops).
As of GCC 4.2, the compiler implements version 2.5 of the OpenMP specification, as of 4.4 it implements version 3.0 and since GCC 4.7 it supports the OpenMP 3.1 specification. GCC 4.9 supports OpenMP 4.0 for C/C++, GCC 4.9.1 also for Fortran. GCC 5 adds support for Offloading. OpenMP 4.5 is supported for C/C++ since GCC 6 and since GCC 7 for Fortran (with omissions, largest missing item is structure element mapping). Since GCC 9, there is initial OpenMP 5 support (essentially C/C++, only). GCC 10 added some more features, mainly for C/C++ but also for Fortran.
GCC 11 (ongoing development) extended the Fortran compiler to fully support OpenMP 4.5 and support more OpenMP 5.0; additionally, nonrectangular loops are now supported.
GCC 11 Changes – work in progress (as of 2020)
GCC 9 Changes – contains a TODO list
Documentation on libgomp (GNU Offloading and Multi Processing Runtime Library).
OpenMP 4.5 specification (November 2015)
OpenMP 5.1 draft (= Technical Report 8) (November 2019)
OpenMP 5.1 draft (= Technical Report 9) (August 2020)
OpenMP 5.1 (November 2020)
Test Suites and Benchmarks
OpenMP task test suite by BSC
Feel free to add new items to this list as you run into issues or features that would be interesting to add. Send mail to the list and/or the GCC OpenMP maintainers if any item in this list sounds interesting but is hard to understand.
Fine tune the auto scheduling feature for parallel loops.
Implement untied tasks (no compliance issue; needs to be well tuned to be actually faster; cf. page 53 of pdf) - see also next item
A comparison for tasks between libgomp, another library (gcc+libKOMP) and Intel (cf. benchmark on p. 10); see also another IOMP 2012 comparison
OpenMP 4.0 (specifications released on July 2013). Cf. slides at the IWOMP, the International Workshop for OpenMP (slides and tutorials) in June 2010 and the OWOMP 2010 proceedings. There is also a blog entry. See also IWOMP 2012's talks and the committee report. SC2011 (November 2011): OpenMP Lang Committee Report, CEO report
And a comment prior to the final release: OpenMP 4.0 about to be released and IWOMP 2013, by Michael Wong (May 2013)