From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 78B243857C66; Wed, 19 Jan 2022 22:51:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 78B243857C66 From: "law at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/103721] [12 regression] wrong code generated for loop with conditional since r12-4790-g4b3a325f07acebf4 Date: Wed, 19 Jan 2022 22:51:06 +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: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: law at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 12.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: 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: Wed, 19 Jan 2022 22:51:06 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103721 --- Comment #9 from Jeffrey A. Law --- I think Andrew has raised a really interesting issue. If the relation code= is designed around seeing things in dominator order, then don't we have to stop using it once we traverse any edge where the edge source does not dominate = the edge destination (assume this is a partial graph rather than a multi-entry function ;-) 1 2 3 | \ / | 4 | / \ +->5 6 / \ 7 8 Note how BB4 does not dominate BB5. If we try to thread something like 2->4->5->?, then can't we run into problems with the equivalence handling as well, even though we're not dealing with a loop?=