Re: PING^2: resubmitted IRA improvement patches

[Mark Mitchell <mark at codesourcery dot com>]

On 10/6/2010 7:08 AM, Vladimir Makarov wrote:

> I feel there is inconsistency in you policy implementation.

I think there's a qualitative difference between back-ends and
front-ends and the entirety of the middle-end.  The middle-end, by
definition, affects all users of the compiler, independent of
programming language or target architecture.  It's vital infrastructure,
and it makes sense to be particularly careful there.  It's a lot easier
to get your head around how some obscure C++ language feature works, or
what sequence of instructions is best on Power, than it is to think
about what heuristics are going to work well across all supported CPUs.

I think you're right that there is perhaps some inconsistency with the
autovectorizer/loop optimizer vs. IRA.  Register allocation and loop
optimization do seem to be approximately similar things.  I'm not sure
why we have reviewers for one and maintainers for the other.

But, I think you're now making a fairness argument.  That's fine, but we
can resolve unfairness between A and B in two ways: by making A like B,
or by making B like A.  So, first, we need to decide which one we like
better.

> I think in general removing global maintainers was a good thing.  But a
> bad thing also happened.  You removed Richard Henderson as a global
> maintainer, a quite actively working person who has unique wide range
> knowledge of GCC, who has never abused this privilege and never had own
> political agenda.

I think it's pretty clear just how talented RTH is and how valuable his
contributions to GCC have been.  Do you know if he has had problems
contributing in the wake of the SC change?

> I am aware about lack of knowledgeable IRA reviewers despite the facts
> that there are four of them.  I'll work on bringing more knowledgeable
> IRA reviewers and I know good candidates.

That sounds constructive.

I'd suggest, however, that it's not particularly constructive to
criticize the current reviewers.  Earlier in this thread you complained
that some of them had never contributed a patch.  That might be true,
but that doesn't mean that they can't usefully review a patch.  Having a
lot of knowledge about compilers and optimization research can allow
someone to provide a useful review even without writing a lot of code in
GCC.  Saying negative things about them isn't going to make them more
eager to review your code.

I'm a little confused with where you're trying to go with this
conversation.  I asked that you wait for review of your patches, and you
agreed to do so.  As I understand it, Kenny is working on reviewing
them.  What is it that you feel is going wrong?

Thank you,

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713