From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22785 invoked by alias); 18 Nov 2013 13:27:38 -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 22746 invoked by uid 55); 18 Nov 2013 13:27:35 -0000 From: "joseph at codesourcery dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/59159] Need opaque pass-through as optimization barrier Date: Mon, 18 Nov 2013 13:27:00 -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: 4.9.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: joseph at codesourcery dot com X-Bugzilla-Status: NEW 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: 2013-11/txt/msg01646.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59159 --- Comment #5 from joseph at codesourcery dot com --- On Mon, 18 Nov 2013, rguenth at gcc dot gnu.org wrote: > I wonder whether a very early pass splitting functions at FENV clobber > points and preventing re-inlining would be a better solution in the end That sounds like a nasty hack, not a sensible solution for properly supporting exceptions and rounding modes. For interval arithmetic you want code changing rounding modes (or using the FENV_ROUND pragma proposed in DTS 18661-1) to be handled reasonably efficiently rather than resulting in a split into separate functions (really, a function with FENV_ACCESS enabled should be inlinable into one without, though I could certainly imagine an initial implementation controlling flags only on a per-function basis and preventing inlining).