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From: "amonakov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug bootstrap/84402] [meta] GCC build system: parallelism bottleneck
Date: Tue, 28 Mar 2023 08:45:00 +0000 [thread overview]
Message-ID: <bug-84402-4-MSB9arnsVH@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-84402-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84402
Alexander Monakov <amonakov at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |amonakov at gcc dot gnu.org
--- Comment #61 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #60)
> > This one is btw. a known issue PR108129.
>
> But the revision only sligthly changes the patterns so I'm very curious
> how it arrived at 30% slowdown.
It adds an extra 'convert2?' to 'nop_atomic_bit_test_and_p' matchers, and since
match.pd expansion works by emitting match subtrees twice for each '?'
component, that gives an extra 2x factor to the already bad combinatorial
explosion going on in those patterns.
We really need to rework match-and-simplify emission in a smarter way. I've
looked at that in January once, but there's a few things I'd need help
understanding, such as...
> The "trivial" improvement of course would be to special-case
> iterator uses als for (match ...) like we do for (simplify ...) where
> we can delay substitution.
... this. Is there a short explanation what's 'delayed substitution' in this
context?
next prev parent reply other threads:[~2023-03-28 8:45 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-84402-4@http.gcc.gnu.org/bugzilla/>
2020-05-07 11:56 ` jakub at gcc dot gnu.org
2020-05-07 22:59 ` egallager at gcc dot gnu.org
2020-07-09 9:44 ` rjiejie at me dot com
2020-07-09 10:04 ` marxin at gcc dot gnu.org
2020-07-09 11:40 ` rguenth at gcc dot gnu.org
2020-07-13 5:51 ` rjiejie at me dot com
2020-07-23 6:51 ` rguenth at gcc dot gnu.org
2021-04-08 12:02 ` rguenth at gcc dot gnu.org
2021-07-19 6:17 ` pinskia at gcc dot gnu.org
2021-07-19 6:19 ` pinskia at gcc dot gnu.org
2021-10-09 12:58 ` egallager at gcc dot gnu.org
2021-10-11 8:01 ` marxin at gcc dot gnu.org
2021-10-11 18:10 ` egallager at gcc dot gnu.org
2021-11-01 4:56 ` egallager at gcc dot gnu.org
2022-05-29 3:44 ` sam at gentoo dot org
2022-06-02 22:05 ` segher at gcc dot gnu.org
2022-11-30 8:13 ` marxin at gcc dot gnu.org
2022-11-30 8:23 ` marxin at gcc dot gnu.org
2022-11-30 8:25 ` rguenth at gcc dot gnu.org
2022-11-30 8:27 ` rguenth at gcc dot gnu.org
2022-11-30 8:38 ` rguenth at gcc dot gnu.org
2022-11-30 9:10 ` marxin at gcc dot gnu.org
2022-12-01 9:43 ` marxin at gcc dot gnu.org
2022-12-01 10:01 ` marxin at gcc dot gnu.org
2022-12-01 10:03 ` marxin at gcc dot gnu.org
2022-12-01 10:07 ` marxin at gcc dot gnu.org
2023-03-27 14:55 ` andrew.carlotti at arm dot com
2023-03-28 3:01 ` marxin at gcc dot gnu.org
2023-03-28 8:30 ` rguenth at gcc dot gnu.org
2023-03-28 8:45 ` amonakov at gcc dot gnu.org [this message]
2023-03-28 8:54 ` jakub at gcc dot gnu.org
2023-03-28 9:05 ` rguenther at suse dot de
2023-03-28 11:31 ` cvs-commit at gcc dot gnu.org
2023-05-05 12:47 ` cvs-commit at gcc dot gnu.org
2023-05-05 12:47 ` cvs-commit at gcc dot gnu.org
2023-05-05 12:47 ` cvs-commit at gcc dot gnu.org
2023-05-05 12:48 ` cvs-commit at gcc dot gnu.org
2023-05-05 12:48 ` cvs-commit at gcc dot gnu.org
2023-05-05 12:48 ` cvs-commit at gcc dot gnu.org
2023-07-07 11:29 ` sjames at gcc dot gnu.org
2023-10-31 12:35 ` cvs-commit at gcc dot gnu.org
2023-10-31 12:48 ` sjames at gcc dot gnu.org
2024-03-04 4:29 ` law at gcc dot gnu.org
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