From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 520EC385840D; Tue, 19 Oct 2021 07:45:38 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 520EC385840D From: "aldyh at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/102814] [12 regression] quadratique/exponential time complexity for max-jump-thread-duplication-stmts Date: Tue, 19 Oct 2021 07:45:38 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 12.0 X-Bugzilla-Keywords: compile-time-hog X-Bugzilla-Severity: normal X-Bugzilla-Who: aldyh at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: aldyh at gcc dot gnu.org X-Bugzilla-Target-Milestone: 12.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: assigned_to cc everconfirmed cf_reconfirmed_on bug_status Message-ID: In-Reply-To: References: 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 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Oct 2021 07:45:38 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102814 Aldy Hernandez changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|unassigned at gcc dot gnu.org |aldyh at gcc dot gn= u.org CC| |amacleod at redhat dot com Ever confirmed|0 |1 Last reconfirmed| |2021-10-19 Status|UNCONFIRMED |NEW --- Comment #3 from Aldy Hernandez --- (In reply to Richard Biener from comment #2) > (In reply to Aldy Hernandez from comment #1) > > Question to the larger audience... do we support bug reports against > > internal --param constructs? >=20 > Yes. Generally 'max-jump-thread-duplication-stmts' would suggest this is > a parameter limiting code size growth and one that might affect compile-t= ime > in a linear fashion - exponential growth here is unexpected. The reporter > states a 180 -> 181 parameter change trips this over unexpectedly which is > a case worth investigating (it suggests a limit elsewhere is missing). >=20 > For example the alias walking code counts the amount of "work" it does and > has a limit on that, allowing linear growth parametrization. Not sure if > there's sth in the threader and/or ranger that would support accumulating > a work budget and stop after it is exhausted, but something like that wou= ld > be very useful (not sure if that's the problem at hand in this case). ISTR Andrew had some patches to stop solving for some combination of extrem= ely large PHIs. Not sure whether this is the issue at hand, but perhaps it's w= orth looking at. I'll put this in the back burner for now, since the loop threading restrict= ions make this a non-issue, but I'll come back to it later. Thanks.=