I converted almost all instructions in insns.dat (version 7a6f97869840fc0b1b8677bd77c74754c5f024aa) to the more readable format that insns.pl has supported for years. I also made some changes to insns.pl. You can verify that the new insns.dat and insns.pl produce byte-identical output to the old insns.dat and insns.pl, so I think that this change is safe to check in, even though it is a large change to insns.dat.
The changes to insns.pl are:
* fixed a bug: ib,u was not recognized
* added support for a second immediate argument called "j" for instructions like ENTER imm,imm
* added a "+r" syntax for \10..\13