From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 71537 invoked by alias); 30 May 2015 23:00:26 -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 71490 invoked by uid 48); 30 May 2015 23:00:22 -0000 From: "sebastiano.vigna at unimi dot it" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/66348] Simple loop has only lower half of the 64-bit counter initialized correctly Date: Sat, 30 May 2015 23:00:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c X-Bugzilla-Version: 4.9.2 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: sebastiano.vigna at unimi dot it X-Bugzilla-Status: UNCONFIRMED 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: 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: 2015-05/txt/msg02480.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66348 --- Comment #2 from Sebastiano Vigna --- Er... it's perfectly possible. My knowledge of x64 assembly is rudimentary, but I wanted to try a diagnosis. What is definitely true is that at -O0 we enter and exit the loop as it should happen, and at -O1 we never exit the loop. For the time being we are #pragma'ing the function to remove optimizations.