SBCL: The Assembly Code Breadboard (2014)

This article discusses optimization techniques for stack-based virtual machines (VMs), inspired by Chuck Moore's F18 architecture and x87 floating-point stack design. The author proposes a novel approach using a small fixed-size stack (8 slots) with a modular counter to track the top of stack, eliminating costly data movement during push/pop operations and enabling specialized primitive variants for each possible counter value. The implementation leverages SBCL's assembler to generate efficient machine code for a direct-threaded VM architecture, where instruction dispatch is optimized by storing primitive variants at regular 4288-byte intervals keyed to the stack counter value.