6502 Code Generator Outperforms GCC and LLVM

A developer built a 6502 code generator that surprisingly outperforms GCC, LLVM, and other compilers. The speed advantage isn't from superior high-level optimizations, but rather innovative code generation techniques. The compiler leverages "illegal" instructions, computationally expensive instruction selection, and space-for-time optimizations. The core algorithm combines instruction selection with register allocation, cleverly using continuation-passing style. It works with a DAG and SSA-form intermediate representation, generating multiple assembly code combinations, pruning with dynamic programming and branch-and-bound, and finally solving a PBQP problem for optimal selection. While employing some "cheats," the compiler shows remarkable benchmark results, offering fresh perspectives on code generation.