I gather that most of the instructions work the same as the S3's, but the P4 has some new instructions and apparently abandoned some form the S3.please refer to Chapter 2 Processor Instruction Extensions [to be added later].
At least the differences to the S3 need to be documented somewhere.
Edit:
Just found
https://github.com/espressif/esp-idf/is ... 3392746085
which points to a TRM release in February (of 2026, I hope