In his latest post Juozas Kaziukenas shares a video of his "From PHP to Machine Code" talk he presented at the PHP UK Conference earlier this year (2016).

I recently gave a talk at a few conferences titled “From PHP to Machine Code”. It explains how compilers and interpreters work in general, where are the performance gains to be found and how I applied all of that to build PyHP. PyHP is a little toy project which showcases the basics of taking source code of a programming language and executing it.

As I mention a few times in the talk, it is completely and utterly useless for practical use, but it’s one of the fundamental skill-sets for any programmer. I think knowing how a bunch of text makes a computer do things at the low level is required knowledge for everyone.

The video of the presentation is embedded in the post or you can watch it directly over on YouTube if you'd like. In it he walks you through the entire process that happens from the time the PHP is executed all the way down to opcodes and bytecodes.