Retiring IPA-branch

[Jan Hubicka <jh at suse dot cz>]

Hi,
thanks to Diego, Andrew (MacLeod), Daniel and Roger's effort on
reviewing IPA branch merge patches, I hope to commit after re-testing
the patch to enable IPA-SSA today. This means that the main part of
IPA-branch has been merged.  There are still features on IPA branch that
I hope to follow shortly (in particular the pre-inline local
optimization, IP-CP on SSA form by Razya and aliasing by Olga), but
those are all rather localized changes.

I would hope to retire that branch, since it has gained a lot of
dust and also a lot of things has been renamed while merging to mainline
making it outdated. Because the branch is actually used as base for
other development, I would like to ask if there is need for some kind of
"transition plan" to mainline.  If so, I can merge mainline into the
branch and remove most of no longer needed stuff, if it seems to make
things easier or do something else. I will be also happy to help with
any problems with updating the code to mainline implementation or,
naturally, solving any issues that appears with the merge.

At the end of stage 1 I would also like to open new branch targeted to
further improvements and cleanups of IPA infrastructure that can
co-exist in parallel with LTO branch solving other aspects we need to
address before getting useable link time optimization.  Issues I would
like to deal with are the further cleanups to make writting IPA passes
more convenient, probably finally solve the multiple declaration
problems on C and fortran frontend (if not done in mainline before
that), write some basic easy IPA passes (such as removing of unused
arugments and return values, some basic argument passing simplificaiton
and similar cheap stuff) and solve as many of scalability issues as
possible.  Again everyone is welcome to help and hope I didn't
discougrated from that by missing stage1 of 4.2 and thus delaying whole
ipa-branch project by a year. I really didn't anticipated the 4.2
schedule to be so delayed and I had problems justify all the changes in
late stage1 of 4.2 without having enought code developed to take
advantage of them.

Honza