Quoting Eric Botcazou <ebotca...@adacore.com>:
set_unique_reg note already makes a number of checks so that its
multitude of callers doesn't have to. E.g. it checks that there is
indeed only one set, not only one set of a live register.
Indeed, but not on the DATUM.
P.S.: The DATUM is in the right mode for the computation that is being done,
from a high-level perspective. The problem is that we don't have an insn
that uses that mode to tag it on to, because the actual implementation of
the computation uses a different mode.
That is really not that much different from ending up with trying to put the
note on an instruction that not only sets the result, but also some
other value.
