tree 2c5f85b24aebde0c0b1503281acf986310835422
parent 24adae9131c74186d0df51c61571a59f69be1a78
author Rupert Swarbrick <rswarbrick@lowrisc.org> 1627048245 +0100
committer Rupert Swarbrick <rswarbrick@gmail.com> 1627061738 +0100

[otbn] Correct illegal_insn detection for register-immediate ops

The list of cases here had a couple of extra entries, leading to
broken decodes (and X propagation!) for some bogus instruction
encodings.

Remove the wrong cases and add comments to the ones that are right to
make it easier to see what's going on.

Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>