A question about PLC architecture and ladder logic
Many modern PLCs have (sometimes multicore) Intel or AMD processors with 64bit. Micro-controllers are rarely used nowadays for high-performance PLCs. These PLCs have their own operating system, mostly based on Linux, or for example Beckhoff is running on Windows Embedded. Ladder logic can be compiled directly, but I don't know who is doing it and who not.

Check this link: https://www.quora.com/How-is-PLC-ladder-logic-converted-to-machine-code-Does-it-really-convert-into-machine-language

EDIT

Some manufacturers have their own processors, not sure, but Siemens I think too. Modern PLCs are more like (real-time) computers than the classic PLCs from the 90s.