Re: IRA for GCC 4.4

[Vladimir Makarov <vmakarov at redhat dot com>]

Mark Mitchell wrote:
> Vladimir --
>
> As I mentioned earlier today, theRMs would like IRA to be included in 
> GCC 4.4.  We feel this is an important improvement with great 
> potential benefit.  However, we also feel that it is very important 
> that, by the time 4.4 is released, we have only one allocator.  We do 
> not want to risk an incomplete transition.  And, while there may of 
> course be some hiccups when including a major new feature, we want to 
> make sure that developers working on other aspects of GCC are not 
> impacted more than necessary.
>
> Therefore, we suggest the following strategy:
>
> * IRA patch should be reviewed by one or more middle-end maintainers 
> for technical design, documentation, and coding style.  I know that 
> you have already been discussing some issues with Kenny, Steven, and 
> others.  I hope that you will continue to work to address issues 
> raised.  I also hope that others will help you to do that.
>
> * Ensure that IRA works for all primary and secondary targets.  You 
> certainly do not need to do this personally, and I hope and expect 
> that the target maintainers will continue to work with you to validate 
> their targets.
>
> * Ensure that IRA performance on SPEC is no worse than old-RA 
> performance on primary targets.  Again, I hope and expect that the 
> target maintainers will work with you to gather data and investigate 
> any issues.
>
> Once these goals have been met:
>
> * Merge the IRA branch to the mainline and make it the default, 
> temporarily leaving the old RA in place for the benefit of any 
> unconverted targets.
>
> * After 30 days, remove the old RA.  During the 30-day period, please 
> work with any target maintainers who are having trouble converting.  
> We will try to remember to warn the maintainers of unconverted targets 
> once or twice during the 30-day period.
>
> Is this strategy acceptable to you?
Mark, thank you for the attention to IRA.  This plan is ok to me.  
Originally I was prepared to existence of two RAs in GCC and to a long 
battle to remove the old RA.  But I've got the same impression from a 
few week discussion that people don't want to have two RA.

I've got already a good feedback and some reviews (the most useful was 
Steven's one).  I took practically all first round comments into account 
and prepared the second version of the patch which I sent a week ago.  I 
am still getting PRs and problems (and sometimes solutions to them) from 
other people for some ports.  But my general feeling that IRA is already 
in a good shape with the stability point of view.  I am also confident 
that IRA achieved (or IRA can achieve if it is not true for some target) 
not worse performance for the primary targets.

I am ready to help all target maintainers to make IRA work right for them.

So the plan is ok to me and I'll work in this direction.

Thank you and all people helping me to achieve this goal.