Compiling and running Cilk

To compile and run a Cilk program using OpenCilk, follow these two steps:

1. Compile the Cilk program using the OpenCilk compiler by passing the additional -fopencilk compiler flag, then
2. Run the resulting executable.

This page provides details on how to compile and run a Cilk program using OpenCilk.

Compiling a Cilk program

You can compile a Cilk program similarly to a C or C++ program by passing the additional -fopencilk flag to clang or clang++, respectively:

$ clang -o fib fib.c -fopencilk -O3

Note: Pass the -fopencilk flag to the compiler both when compiling and linking the Cilk program. During compilation, the flag ensures that the Cilk keywords are recognized and compiled. During linking, the flag links ensures the program is properly linked with the OpenCilk runtime library.

The OpenCilk compiler is based on a recent stable version of the clang compiler. It supports all compiler flags and features that the ordinary clang compiler supports, including optimization-level flags, debug-information flags, and target-dependent compilation options. See the Clang documentation for more information on the command-line arguments.

Running a Cilk program

To run the Cilk program, simply invoke the compiled executable binary:

$ ./fib 42

You can use the CILK_NWORKERS environment variable to run the Cilk program with a specific number of workers. The following example runs the fib executable using 8 Cilk workers:

$ CILK_NWORKERS=8 ./fib 42