Re: call_insn's and argument locations

[David Edelsohn <dje at watson dot ibm dot com>]

>>>>> Chris Lattner writes:

Chris> This is something that could/would be fixed by introducing a new level of
Chris> IR into GCC (which has been discussed many times before).  AFAIK, it is a
Chris> critical issue for many future developments in GCC
Chris> (http://linuxia64.org/gcc_summit.2001.06.06.html)... but there doesn't
Chris> seem to be an active project addressing it [Tree SSA is the closest thing
Chris> to a new IR, but it's really not low level enough IMHO].

Chris> What is the limiting factor here for a new IR?  Is it the FSF's views on
Chris> not letting GCC be used piecemeal as part of a commercial product?  Is it
Chris> that there is no agreement on what a new IR should look like (a touchy
Chris> subject)?  Or, is it that there is just noone who is interested/has time
Chris> to work on it?

Chris> I have some time that I could put towards this, but don't want to step on
Chris> peoples toes here.  :)

	The limiting factor is having an actual design on which people
have commented, as opposed to various people doing work in secret and
contributing a completed implementation on which the entire GCC
development community was able to comment.  Not everyone will be happy
with the resulting design and we are not trying to design this via
committee, but a new IR level is a large change having long-term impact in
GCC development.

	The IR is a major issue for the efforts getting underway to
address GCC infrastructure needs.  I personally think it is better to
avoid constraining that effort with piecemeal baggage so that it does not
need to throw too much away and waste everyone's effort.  GCC has been
approaching this limitation for years and there is no need to rush to
solve these fundamental problems over night.

	We have had discussions about a new IR a few times.  If we want to
re-open that discussion to refine the ideas more, that could be useful.

	The biggest problem that I have seen in GCC development is a lot
of uncoordinated, isolated projects without a core design and overall goal
in place.

David