There’s no tracing in either JägerMonkey or IonMonkey. That’s just a confusing statement about the similarity of speculation guards and OSR exits to trace guard

There’s no tracing in either JägerMonkey or IonMonkey. That’s just a confusing statement about the similarity of speculation guards and OSR exits to trace guards and side exits. For a while TraceMonkey was used as a higher tier above JägerMonkey which might be what you’re thinking of? I don’t work for Mozilla but spent a ton of time studying TraceMonkey for building my own tracing JIT.