Am 2019-12-08 01:54, schrieb Oleg Endo:
On Tue, 2019-11-26 at 07:38 +0100, ste...@franke.ms wrote:
> On 11/21/19 10:30 AM, ste...@franke.ms wrote:
> > Hi there,
> >
> > here is mc68k's patch to switch the m68k architecture over to ccmode
> > and
> > lra. See https://github.com/mc68kghost/gcc 68k-ccmode branch.
>
> Bernd Schmidt posted a conversion of the m68k port to ccmode a couple
> weeks before yours. We've already ACK'd it for installing onto the
> trunk.
>
> Jeff
To be honest:
- 8 days is hardly "a couple weeks before"
- ccmode is not the same as ccmode+lra
The paperwork for contributing to fsf is on the way and the repo at
https://github.com/mc68kghost/gcc got an update. Tests are not yet at
100%
(master branch fails too many tests) but it's closer to master branch
now.
The code is to 50% identical, a fair amount has swapped cmp/bcc, few
are a
tad worse and some yield surprisingly better code.
You can still submit patches for further improvements, like adding
support for LRA. Now that the main CCmode conversion is on trunk and
has been confirmed and tested, it should be much easier for you to
pinpoint problems in your changes.
Cheers,
Oleg
The problems are in the gcc implementation
- the lra implementation is buggy
- the compare elimination can't handle parallel's containing a compare
- df-core considers parallel's containing a compare also as a USE
- some optimizations/mechanisms do only work if HAVE_CC0 is defined
- way more ...
And the current implementation is IMHO unusable for lra since it did not
introduce a CC register to track clobbering. So it's a dead end.
I can live with the fact that my patch was refuted since I simply use my
*working* fork, where I fixed the issues mentioned above.
/cheers
Stefan
