It's interesting to read the OP's response to partial evaluation (employed by Truffle) and why he switched to meta-tracing in RPython. Basically, the inlining/s

It's interesting to read the OP's response to partial evaluation (employed by Truffle) and why he switched to meta-tracing in RPython. Basically, the inlining/specialization decisions in PE-based JITs were harder to control than just letting the VM observe loop iterations. Here's a paper regarding a pair of language implementors' experience using both techniques: http://stefan-marr.de/papers/oopsla-marr-ducasse-meta-tracing-vs-partial-evaluation/ http://stefan-marr.de/papers/oopsla-marr-ducasse-meta-tracin... By changing the abstract syntax tree during execution, type-generic nodes in the AST can be replaced with type-specialized nodes. This carries more overhead than tracing through the interpreter. It also requires more explicit work from the user to achieve optimized results. The authors of the above study conclude that the resulting performance was similar, but that meta-tracing was an easier technique to use than PE. This agrees with the OP's assessment.