CppCon 2026

A chess engine must search millions of positions per second. Move generation is often a bottleneck. Generating moves for knights, kings, and pawns are computationally cheap (~1 nanosecond). However, rooks, bishops, and queens (aka "sliding pieces") present a unique challenge: their movement depends on the placement of other pieces. This makes on-demand generation too slow (20+ nanoseconds) and naively-implemented lookup tables impractical (requiring zettabytes of RAM).

We will start by reviewing the core data structures in a chess engine and the logic behind move generation. Then, we will explore "magic bitboards", a perfect hashing technique that enables sliding piece move generation in ~1 nanosecond. We will look at how to implement this in modern C++, comparing hardware-specific instructions like PEXT (Parallel Bits Extract) against a portable software approach. Finally, we will discuss the practical challenges of generating the data structures required for magic bitboards, including the limitations of consteval and how to integrate build-time table generation into the build process using Bazel.

To ground these concepts, we will be referencing implementation details and code from my C++ chess engine, FollyChess.