False-positive decoding on AMD64: INTO

[woodruffw]

Hi there, mishegos maintainer here.

It looks like bddisasm currently treats CEh as a valid decoding for INTO (i.e., interrupt level 4 if FLAGS.OF=1) in 64-bit mode. This is incorrect -- CEh is only INTO in 32-bit mode, and is invalid in 64-bit mode.

Some examples (the first two columns are XED and Zydis reporting that the decoding is invalid; the third is bddisasm incorrectly reporting a valid decoding):

ce	(0 / 0)	(0 / 0)	INTO (1 / 4)

Similarly, prefixed versions should also be treated as invalid in 64-bit mode:

6667f365ce	(0 / 0)	(0 / 0)	INTO (5 / 4)

From the AMD developer's manual: