From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11209 invoked by alias); 12 Dec 2013 18:09:19 -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 11159 invoked by uid 48); 12 Dec 2013 18:09:15 -0000 From: "ubizjak at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/56339] [4.8 Regression]: Suboptimal register allocation Date: Thu, 12 Dec 2013 18:09:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 4.8.0 X-Bugzilla-Keywords: missed-optimization, ra X-Bugzilla-Severity: normal X-Bugzilla-Who: ubizjak at gmail dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.8.3 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: short_desc 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-SW-Source: 2013-12/txt/msg01084.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D56339 Uro=C5=A1 Bizjak changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|[4.8/4.9 Regression]: |[4.8 Regression]: |Suboptimal register |Suboptimal register |allocation |allocation --- Comment #17 from Uro=C5=A1 Bizjak --- gcc-4.9 now generates: f: addsd %xmm2, %xmm0 ret The problem is fixed in 4.9, reconfirmed on 4.8 branch. >>From gcc-bugs-return-437430-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Thu Dec 12 18:12:20 2013 Return-Path: Delivered-To: listarch-gcc-bugs@gcc.gnu.org Received: (qmail 12724 invoked by alias); 12 Dec 2013 18:12:19 -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 Delivered-To: mailing list gcc-bugs@gcc.gnu.org Received: (qmail 12678 invoked by uid 48); 12 Dec 2013 18:12:14 -0000 From: "eggert at gnu dot org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/52904] -Wstrict-overflow false alarm with bounded loop Date: Thu, 12 Dec 2013 18:12:00 -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: 4.7.0 X-Bugzilla-Keywords: diagnostic, missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: eggert at gnu dot org 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: 2013-12/txt/msg01085.txt.bz2 Content-length: 730 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52904 --- Comment #6 from eggert at gnu dot org --- > That diagnostic seems right, according to the documentation of -Wstrict-overflow. The diagnostic is "right" only in the sense that it is correctly reporting that GCC does not deduce that signed overflow cannot possibly occur in this function. It is not "right" in the common sense that a programmer would ordinarily want, i.e., that the program may have a bug because signed overflow might lead to undefined behavior. (Surely the diagnostic is supposed to be for the benefit of programmers trying to find potential bugs in their programs, not for the benefit of GCC maintainers trying to explain how GCC works internally. :-)