From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 3C81C3858D39; Tue, 28 Mar 2023 03:01:20 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3C81C3858D39
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1679972480;
	bh=PcZx+Tljr08dTKVQq0Sx7+ZdArm3lgw5nTuW7h6o+vc=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=GV60l3hUTKp4ZaAivzBJgv7+ll3YpXh5xo9Hf+Tlxl/ih2ti0rVT8Z75UplkPzqCo
	 Shgj7Dx+P9gW7AIqihMOcCWlJJv3qM4TysWzn9YsWuxaz0/DWdimTSQPKkL1twGlG3
	 +L+fW1XWRONr3ClS6gVepaoqy8Xk+jATZ1ruWK7w=
From: "marxin 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 03:01:18 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: bootstrap
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: build, meta-bug
X-Bugzilla-Severity: normal
X-Bugzilla-Who: marxin at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-84402-4-wWqZgMNNh4@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-84402-4@http.gcc.gnu.org/bugzilla/>
References: <bug-84402-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D84402

--- Comment #59 from Martin Li=C5=A1ka <marxin at gcc dot gnu.org> ---
(In reply to Andrew Carlotti from comment #58)
> Since November 2021, there's been a significant regression in the compile
> time for gimple-match.cc during a bootstrap build (+100% in Stage 2, +73%=
 in
> Stage 3), with this regression accounting for over 20% of the current tot=
al
> bootstrap time on some aarch64 machines.

Thank for the interesting numbers! Yeah, it's very unfortunate :/

>=20
> Most of the change in compile time is due to the following 6 commits (of
> which one is a performance improvement, and one only regressed the Stage 2
> build):
>=20
> 7df89377a7ae3906255e38a79be8e5d962c3a0df 24th November 2021
> Enhance optimize_atomic_bit_test_and to handle truncation. (Hongtao Liu)
> Stage 2: +27%
> Stage 3: +33%

This one is btw. a known issue PR108129.=