From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18179 invoked by alias); 30 Dec 2013 17:53:00 -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 18155 invoked by uid 48); 30 Dec 2013 17:52:56 -0000 From: "glisse at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/59615] "asm goto" output or at least clobbered operands Date: Mon, 30 Dec 2013 17:53:00 -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: unknown X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: glisse at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED 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: 2013-12/txt/msg02418.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59615 --- Comment #6 from Marc Glisse --- (In reply to Jakub Jelinek from comment #4) > Anyway, you definitely don't want > to use inline asm in this case, if there is some code GCC doesn't optimize > as good as you'd like to, just report that. One common similar case where people are tempted to use asm goto with an output operand is, on x86: compute a*b and check if it overflowed. x86 has flags for that but AFAIR they are not modeled in the .md files. (I was also interested in output operands for asm goto in PR52381, but there is no good example there)