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Re: What to do with new-ra for GCC 4.0


neroden@fastmail.fm (Nathanael Nerode) writes:

> Steven Bosscher wrote:
> >Perhaps not so surprisingly, new-ra is completely broken on mainline
> >at the moment.  Literally not a single non-empty file will compile
> >with -fnew-ra.
> >
> >First of all there is a bug in ra-build.c:live_in() which has been
> >there since the merge from the edge-vector-branch.  Then we hit an
> >ICE on sibcalls in ra.c:reg_alloc(), which also must have been there
> >since ages.  The patch below sort-of fixes these two issues.  But
> >then we hit SUBREG problems, probably due to rth's stricter subreg
> >patches.  At that point I gave up.
> >
> >So, any nontrivial code will ICE with -fnew-ra.  I hate to bring up
> >painful issues, but I would like to propose we remove all of new-ra
> >for GCC 4.0 as it is complete and utterly broken anyway, and given
> >that it has been broken for months without anyone complaining, it's
> >not like anyone will miss it.
> >
> >Thoughts?
> 
> That sucks?
> 
> The structure of the new-ra files is really reasonably elegant; it would
> be sad if it couldn't be salvaged.
> 
> Are there major structural defects in it, which would be remediated best by
> writing a graph-coloring register allocator from scratch, or is it just
> suffering from bitrot?
> 
> How many people understand the code?  :-)  Would more workers help?

I think that now only three persons understand the new-ra code.
Thay are:
1. Michael Matz;
2. Denis Chertykov;
3. Daniel Berlin (he is out from the new-ra few years ago, but I think
                  that he understand the code)


More workers are welcome !

Denis.

> 
> 
> -- This space intentionally left blank.


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