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Re: IA-64 GCC deprecation?

On Thu, Jun 13, 2019 at 11:31 AM John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
> I don't understand why it would be so important to deprecate ia64 so quickly
> now given the fact that both Debian and Gentoo are actively working on the
> port.

The IA-64 port has been broken on and off ever since we added some
qsort checking.  That happened in Sept 2017.  So the port has been
broken for about a year and a half now.

Intel has already announced EOL for IA-64 in Fall of 2020.  The next
gcc release is spring 2020, so not clear that we need support for a
soon to be dead processor.  You can still use old gcc versions for
IA-64, it just wouldn't be supported in new releases if it gets

I wasn't aware of a gentoo IA-64 effort, but checking, it looks like
gentoo-ia64 has no email since October 2006.  That doesn't look like
an active project.

> Is there anything that the ia64 backend is currently blocking in gcc?

We still get bug reports for it.  Someone has to answer the bug
reports.  If there is no dedicated IA-64 maintainer, then one of the
global maintainers has to handle it, and they don't want to do this

Sometimes we have to make global changes to gcc which require changes
to multiple backends.  The general process is to test every backend
that is touched, but if you have to touch the ia64 backend, and the
ia64 backend is broken, then you can't touch it.  People don't like
making blind changes that they can't properly test.

There are some optimization passes and infrastructure features that
are used primarily or only by the IA-64 backend.  If we can deprecate
the ia64 port, then we can perhaps deprecate these features, which
then lowers the maintenance burden for people working on other parts
of the compiler.

This all hinges on whether the IA-64 port has a maintainer or not.  If
someone here wants to volunteer as the IA-64 port maintainer, then you
can keep the port alive for a while longer.  It is still likely to be
deprecated eventually though.  There are so many things that are
different about IA-64 than everything else that gcc supports that this
creates a maintenance burden even for people who aren't doing IA-64
work.  So it is really only practical to keep it alive if it has
value, and an EOL processor doesn't have much value.

I was keeping the IA-64 alive for a few years by serving as a token
maintainer, but my RISC-V work has increased to the point where I
can't reasonably pretend to be the IA-64 maintainer anymore.  So now
that there is no official maintainer they want to deprecate it.

If you care about this, I would suggest contributing to the thread on
the gcc mailing list.


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