Re: Bountysource campaign for gcc-vax

[David Brownlee <abs%absd.org@localhost>]

On Mon, 7 Dec 2020 at 13:57, Maciej W. Rozycki <macro%linux-mips.org@localhost> wrote:
>
> On Mon, 30 Nov 2020, Maciej W. Rozycki wrote:
>
> > > Any update on when these will get merged? Looks like Jeff is fine with most
> > > of the patches.
> >
> >  Well, 01/31 has turned out the most troublesome, required review effort
> > from several people, and taken an extra verification cycle, i.e. ~2 days,
> > but has been approved by Ulrich as of last Fri, and acknowledged by Jeff
> > too.  All the remaining patches (except for 29/31, a PDP-11 fix, obviously
> > not strictly required for our purpose, approved separately by Paul Koning)
> > have been previously reviewed and approved by Jeff.
>
>  As it turned out I previously slipped over the review of 08/31 and missed
> concerns Jeff had as to how the change may make jump optimisation happen
> where it is not supposed to.  I came across the message while making sure
> I haven't missed anything and the resulting investigation cost me extra
> few days and another two regression verification cycles.
>
>  In the end Jeff's concerns were not unfounded, though my original change
> was actually sound and I have only updated a comment there according to my
> findings.  In the course of the investigation however I discovered and
> fixed no less than five middle end bugs where jumps were handled in a
> dangerous manner, the fixes for all of which have been accepted for GCC
> 11, and a somewhat related buglet the fix for which has been accepted for
> GCC 12 only on the side of caution.
>
> >  I'm going to verify and submit an extra change that I'd like to go in
> > ahead of the actual MODE_CC conversion (i.e. 30/31), which is to fix the
> > LTO issue observed mentioned here and along with the upstream submission,
> > as I think it is important and might be worth backporting.
>
>  The fix has been posted:
>
> <https://gcc.gnu.org/pipermail/gcc-patches/2020-November/560640.html>
>
> and accepted, commit e552abe2ba27 ("PR target/95294: VAX: Convert backend
> to MODE_CC representation").
>
> >  This will remove the sole regression, which I found a sore point in the
> > whole effort.  Not a perfect fix, as a better one I have made turned out
> > to trip on a linker bug in BFD, but certainly a working one, and good
> > enough for now.  The better fix will have to wait for GCC 12 along with
> > any other improvements.
>
>  The BFD fix has also been posted:
>
> <https://sourceware.org/pipermail/binutils/2020-December/114389.html>
>
> and accepted, commit 0fcf331bb133 ("VAX/BFD: Do not warn about GOT addend
> mismatches if no GOT entry is made").
>
> >  So I think the current ETC is this coming Wed.  Do you have any specific
> > reason to ask?
>
>  I pushed all the changes over the weekend, with the MODE_CC conversion
> specifically:
>
> <https://gcc.gnu.org/pipermail/gcc-cvs/2020-December/338657.html>
>
> and all the patches, the total count of which ultimately worked out at 37,
> included in the same push.  I'll yet see if there are any loose ends to
> tie, but in any case the objective has been reached.
>
>  Questions, comments?

Awesome stuff!

Just an idle question - at some point in the future might you be
interested in another bounty in a similar area? :-p :-p :-p

David