RFC: some target macro->hook conversions

[DJ Delorie]

One of the projects I'm working on needs some extra parameters to some
of the target macros (some of the macros need to be sensitive to the
function being compiled/called).  I know gcc is in stage 2, and that
I'll need to convert these macros to target hooks before doing
anything with their API, so I'd like to propose a mostly mechanical
conversion of some of the macros.

I know I need these changed so far:

PRETEND_OUTGOING_VARARGS_NAMED
RETURN_IN_MEMORY
STRUCT_VALUE
STRUCT_VALUE_REGNUM

I'll probably need more as I work through the project, but the exact
list isn't important at the moment.  What is important to me at the
moment is what process I should prepare for, so I don't waste my time
doing things in the wrong order ;-)

My questions are:

* Would such a change be acceptable at this time?

* Should I change whole blocks of funtionally-grouped macros at once,
  or only the ones that need changing?  IOW, if I need to change
  RETURN_IN_MEMORY, do I need to change all the macros in
  http://gcc.gnu.org/onlinedocs/gccint/Aggregate-Return.html ?  (Some
  macros are used via #ifdef and would not be suitable for such
  mechanical changes at this point, although I might need to "fix" one
  or more of those eventually too)

* Where on the scale between "a zillion small patches" and "one big
  patch" would be best?

* How much testing would be needed to get the warm-n-fuzzies for this
  type of mostly mechanical change?