Overall this looks worthwhile, thanks for submitting it.  I hope you have the time to fix up the minor issues I spotted.

util/tracediff (Diff revision 3)

Shouldn't this default to "." not ""?  Otherwise it looks like the code below will place the trace files in the root dir rather than the current dir if -p isn't specified.

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util/tracediff (Diff revision 3)

I think this code breaks if you specify both -p and -n in that order (it'll pick up the -p and not the -n).  That may not be a common combination but it would be nice to get it right anyway.  Seems like we really need a while loop that checks for $ARGV[0][0] eq '-' or something like that (or use the perl equivalent of getopt or parseargs or something, but that could be overkill).  It's been a long time since I've done much perl so I can't be more specific than that.

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util/tracediff (Diff revision 4)

Don't you want to fold the if & while together into:

  while (@ARGV >= 1 && ($ARGV[0] eq '-n'|| $ARGV[0] eq '-p'))

otherwise I think you could have a problem if someone ran:

   ./tracediff -n

because the while loop will iterate checking $ARGV[0] even if all the args have been consumed.