From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 98926 invoked by alias); 5 Oct 2015 15:25:15 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 98325 invoked by uid 48); 5 Oct 2015 15:25:09 -0000 From: "law at redhat dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/67816] [6 Regression] ICE in duplicate_thread_path, 186.crafty fails to build Date: Mon, 05 Oct 2015 15:25:00 -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: 6.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: law at redhat dot com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: law at redhat dot com X-Bugzilla-Target-Milestone: 6.0 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2015-10/txt/msg00344.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67816 --- Comment #12 from Jeffrey A. Law --- As I suspected, what's happening is we've got an FSM jump thread path. After we register the FSM path DOM discovers that a block embedded in the path has a control statement with a staticly computable destination. DOM cleans things up the obvious way. That leaves blocks in the FSM path which become unreachable. That in turn triggers the checking assert. The checking assert is a simple sanity check on the FSM path to detect a case where a block on the path unconditionally transferred control to another block that was not the next block on the path. That assert detects a "shouldn't ever happen case" and is probably totally obsolete at this point. I'm much more concerned that this didn't trigger is a normal development build and that's what I'm focusing my energy on at the moment.