This is a patched version of Csmith designed to support reducing Csmith generated programs with Hypothesis. It is very much a proof of concept designed to validate how well Hypothesis performs with real world random test-case generators written without its internals in mind, and is not intended for serious usage outside of those experiments.
You almost certainly want the original Csmith, which can be found at https://github.com/csmith-project/csmith.