From: Thomas Koenig <tkoenig@netcologne.de>
To: Toon Moene <toon@moene.org>, gcc mailing list <gcc@gcc.gnu.org>
Cc: gfortran <fortran@gcc.gnu.org>
Subject: Re: Test with an lto-build of libgfortran.
Date: Thu, 28 Sep 2023 07:33:07 +0200 [thread overview]
Message-ID: <a338b60c-5aef-4aa1-2d15-8989b5e49250@netcologne.de> (raw)
In-Reply-To: <9e347fa4-1940-46c6-a5c9-899cf5a7ae85@moene.org>
Hi Toon,
> During the GNU Tools Cauldron we discussed (at the BoF: IPA & LTO) the
> possibility (and hazards) of building the run time libraries for various
> compilers with -flto, enabling an -flto -static linking of programs with
> the run time library available during link time optimizations.
This would be a big win for libgfortran, especially the array functions,
knowing that stride==1 can be a _big_ win for optimization. This is
why LTO is such an excellent idea for Fortran in general, and for the
library in particular.
There is a PR on this with quite some discussion already,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77278 .
I've put you in CC of that bug, maybe we can discuss there more
in detail.
One point about the array functions: In the library, we use sort of a
ripple carry algorithm to step through the arrays. This saves space
an is general, but the performance (esp for the most common one-and
two-dimensional arrays) can suffer.
[...]
> The full question of "lto-ing" run time libraries is more complicated
> than just "whether it works" as those who attended the BoF will recall.
I didn't attend the Cauldron (but that discussion would have been
very interesting). I think for libgfortran, a first step would be
additional work to get declarations on both sides to agree (which is
worth doing anyway).
Best regards
Thomas
next prev parent reply other threads:[~2023-09-28 5:33 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-27 18:21 Toon Moene
2023-09-27 21:48 ` Jeff Law
2023-09-28 6:25 ` Richard Biener
2023-09-28 6:29 ` Andrew Pinski
2023-09-28 7:29 ` Tobias Burnus
2023-09-28 9:51 ` Jakub Jelinek
2023-09-28 11:00 ` Tobias Burnus
2023-09-28 11:02 ` Jakub Jelinek
2023-09-28 5:33 ` Thomas Koenig [this message]
2023-09-28 19:03 ` Toon Moene
2023-09-28 19:26 ` Jakub Jelinek
2023-09-28 19:59 ` Toon Moene
2023-09-28 20:02 ` David Edelsohn
2023-09-29 10:26 ` Andrew Stubbs
2023-09-29 6:03 ` Thomas Koenig
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