Re: [RFC] JIT

On 1 Feb 2019, at 18:30, Larry Garfield <larry@garfieldtech.com<mailto:larry@garfieldtech.com>> wrote: I'm... not sure how that answers my question? I'm saying "if we had a VM+JIT, and the JIT part made feature X acceptably fast but it wasn't acceptably fast with just the VM, is that a problem?" Or is that a situation that cannot happen? Or that we don't care if it happens? Technically, you're absolutely right that this may happen. For instance, if we decide to implement certain features in userland, factoring in the fact that JIT makes it fast enough - but without JIT it would be prohibitively slow - this could be a problem. I do think that if we’d want to go in this direction, our platform support would likely have to be wider than it currently is. But there are still two things that mitigate this issue to a large degree: 1. Our VM is super quick, by far the quickest non-JITted dynamic language (to the best of our knowledge). So VM would be slower, but depending on the specific use case - probably not dead slow. 2. Most PHP production workloads are on Linux, and as far as I can tell this trend is only growing over the years - with virtual machines and now containers becoming more and more popular - meaning that even developers with other host OSs still use Linux for the actual PHP development. That said, again, we should probably evaluate it thoroughly before we come to rely on JIT for any must-have functionality. Zeev