Re: BountySource campaign for gcc PR/91851

[Georg-Johann Lay <gjl at gcc dot gnu dot org>]

John Paul Adrian Glaubitz schrieb:
> On 10/31/19 10:00 PM, Georg-Johann Lay wrote:
> > > > I didn't follow the lists for some time...  At least neither v9 or v10
> > > > release notes caveats mention such deprecation, neither is there
> > > > respective PRs for the cc0 targets.
> > > https://gcc.gnu.org/ml/gcc-patches/2019-09/msg01256.html
> > >
> > > Peter
> > Ah, thanks.
> >
> > So finally, the time has come to move to clang/llvm ?
>
> Not quite. Motorola 68k is currently not officially supported by LLVM/Clang.

For AVR -- an other port affected by cc0 removal -- there is a 
LLVM/Clang port.  It' not as mature as GCC's avr port, but what counts 
in the end is support / responsiveness from the community and an 
openness for the requirements of deeply embedded targets.  I had gcc 
patches rejected by global maintainers (just a no-op hook for other 
targets) because it appeared they didn't even understand what the patch 
is about (and kept proposing alternative "solutions" that totally missed 
the point).

And code quality is deteriorating from version to version.  Whatever you 
do in the backend to mitigate it, there's always global changes that 
shreds any improvements...

Btw, does GCC support clobbering registers in branches (or 
cbranch<mode>4 for that matter)?  This requirement would come up when 
transitioning avr to cc_mode because cbranches would live post reload.

Johann


> There is a port that is half-finished though [1] and there is also one guy from
> Czech Republic who wrote a Bachelor thesis on an m68k backend for LLVM [2]. I
> have not been able to contact him though as his university address bounces.
> I would love to see the code that was written there.
>
> I have also played around with Rust on m68k based on the LLVM code on [1], but
> it doesn't really work yet. I think finishing LLVM for m68k would be another
> idea for a Bountysource campaign.
>
> Adrian
>
> > [1] https://github.com/M680x0/M680x0-llvm/
> > [2] https://www.vutbr.cz/en/students/final-thesis?zp_id=34902
> > [3] https://github.com/glaubitz/rust/tree/m68k-linux