SquirrelFish

SquirrelFish is a register-based, direct-threaded, high-level bytecode engine, with a sliding register window calling convention. It lazily generates bytecodes from a syntax tree, using a simple one-pass compiler with built-in copy propagation.

SquirrelFish’s bytecode engine elegantly eliminates almost all of the overhead of a tree-walking interpreter.

1. First, a bytecode stream exactly describes the operations needed to execute a program. Compiling to bytecode implicitly strips away irrelevant grammatical structure.
   
   
2. Second, a bytecode dispatch is a single direct memory read, followed by a single indirect branch. Therefore, executing a bytecode instruction is much faster than visiting a syntax tree node.
   
   
3. Third, with the syntax tree gone, the interpreter no longer needs to propagate execution state between syntax tree nodes.

출처: Announcing SquirrelFish via Simon Willison’s Weblog

P.S> SquirrelFish - Wikipedia