md description for intruction that modifies multiple operands

[Richard Kenner]

    I thought each unspec had to have a unique number.

Not necessarily.  They have to be used in a unique *way*, though.  In other
words, there's no requirement for an UNSPEC that's only used in a PLUS to
have a distinct number from one that's only used in a MINUS.

However, it's much clear from a documentation point of view if they are
unique, of course, and since you're not going to run out of possible value,
there's no reason *not* to make them unique.