This feature is needed for a chess GUI application because the Stockfish chess engine is offered in different builds: a build that supports the POPCNT processor instruction and a build that doesn't, a build that supports the BMI/BMI2 processor instruction set, a 32-bit build and a 64-bit build, also a Windows build and a Linux build.

Then the chess GUI application can check if the processor supports the POPCNT instruction or the BMI/BMI2 processor instruction set and can load an appropriate Stockfish build to analyze a chess game or play against a human chess player by using the appropriate Stockfish build for the machine the chess GUI application is running on.