Intel® Cilk™ Plus specification and runtime ABI freely available for download

Today, Intel has published the specification for the language and the runtime ABI for Intel® Cilk™ Plus on

This is an important step as Intel encourages adoption of these important capabilities in all compilers.  Intel is in early stages of discussions with others on how to best do this, and all agree that publishing a specification is a very important next step for the success of Cilk Plus.

It is clear that that promoting a specification without an implementation would be a poor way to promote a language. Having an implementation that allows serious evaluation is a must. That is why Intel chose to do it in this order: implementation first, followed shortly by a specification.

Intel has full support for Cilk Plus in Intel’s released compilers on Windows and Linux. These compilers and specifications build upon people, expertise and technology acquired from Cilk Arts last year. In a little more than a year, Intel went from acquisition to products, public specifications and early customer usage. Together these help developers program for multicore processors now and better prepare for a many-core processor future. Evaluation copies of these compilers are available on  The feedback and reception for Cilk Plus has already been very encouraging.

An introduction, including sample code, is available separately, also at I recommend starting with the evaluator's guide for Cilk Plus to take Cilk Plus for a spin!

C and C++ were not designed as parallel programming languages. Intel® TBB solved this, quickly becoming the most popular solution. Cilk Plus complements TBB to address two important things which TBB did not: involving the compiler and direct mechanisms for data parallelism. You might enjoy reading “What Cilk™ Plus solves for C and C++ programmers” if you are interested in a little more history (Cilk Plus started in M.I.T. in the 1990s, spun out into the company Cilk Arts, and joined Intel in 2009) and motivation behind Cilk Plus.

Intel is committed to shepherding Cilk Plus to the industry-wide usefulness through broad adoption and porting, as seen through the company's participation with OpenMP and with TBB. Intel looks forward to the feedback and community involvement that will make that possible.

I hope you take Cilk Plus for a spin and drop Intel a note with your feedback.

James Reinders

*OpenMP is a trademark of the OpenMP Architecture Review Board.
*Cilk is a trademark of Intel Corporation. Intel plans to make it available for use by compilers that implement the Cilk Plus specification.

For more complete information about compiler optimizations, see our Optimization Notice.