Loop optimizer issues

[Zdenek Dvorak]

Hello,

> > I am basically done with the work on rtl-level optimizer.  There are still
> 
> Whooo-hoooo!  Nice work :-)
> 
> Is sibcall now the only pass that trashes the CFG?
> 
> > I think it is a good time to merge it into tree-ssa. I have tested it and there
> > are no real conflicts, so it should not be problematic.
> 
> The problem may not be in conflicts but in QA: How are you going to be
> able to assert that tree-ssa and rtlopt are achieving their goals when
> other new infrastructure is also being merged?
> 
> AFAIK rtlopt is mostly orthogonal to tree-ssa.  Tuning, comparing, and
> improving the new frameworks with resoect to the existing code should
> therefore also be done separately (especially considering the long list
> of open issues you mention).  You could merge without disabling the old
> loop optimizers, but then your reason for merging (better testing
> coverage) is probably not going to happen.
> 
> So I think it is a bad idea to merge code from one branch into the
> other, unless it is also merged into the mainline.

there was discussion about this about a month ago and I had feeling
people mostly agreed with the idea of merging.  My main reason is that
I would like to heavily share code between rtl-level loop optimizer
and tree-level loop optimizer I would like to work on.

Zdenek