Re: [RFC] Contributing tree-ssa to mainline

[Daniel Berlin <dberlin at dberlin dot org>]

On Jan 16, 2004, at 9:17 PM, Kaveh R. Ghazi wrote:

> > From: Gabriel Dos Reis <gdr@integrable-solutions.net>
> >
> > "Kaveh R. Ghazi" <ghazi@caip.rutgers.edu> writes:
> >
> > | I would echo Gerald and Joseph's comments about regressions and
> > | documentation.  (However IMHO, it's up to frontend maintainers to
> > | upgrade their bits, so Ada and g77 not working is okay with me.)  I
> >
> > I don't understand that argument.
> >
> > If someone contributes a patch that suddenly makes a front-end
> > non-working, we consider that a non-starter and reject the patch
> > until it addresses the "non-working" bits.  I do not consider it fair
> > to change the mainline in a disruptive way for x front-ends and says
> > it is x front-ends maintainers' business to make it work.
>
> My feeling on this matter is purely in the context of all those
> goodies promised.  If the new infrastructure is really that good, and
> we all agree this is the "future" of GCC, I can live with some
> frontends not working and asking it's community to pitch in and
> upgrade it.
>
> Feel free to disagree with me.  But remember, they (tree-ssa
> advocates) promised a lot.

Most of which has been delivered, or at least, is in the process of 
being delivered:
"
1.  Better codegen from new and improved optimizations, some easier or
    only possible in an SSA framework.
"

Definitely true, as shown by things like SRA.


"2.  Deletions of major gnarly old parts of GCC which would make
    maintenance easier.
"
Various parts of the C expanders (which weren't pretty) have been 
deleted, and other code is starting to be deleted or significantly 
reworked to be much simpler.
One of the goals was to enable this to occur  This goal has *certainly* 
been successful. The goal of actually doing it is in process, of 
course.



>  If it turns out to be just a different
> infrastructure, as opposed to a better one, I wouldn't feel the same.
It is a better infrastructure.
A much better one.
I'll leave it to Diego and others to post performance numbers besides 
SPEC (though i'm happy to do so if necessary).