From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14044 invoked by alias); 1 Nov 2010 13:21:49 -0000 Received: (qmail 14035 invoked by uid 22791); 1 Nov 2010 13:21:49 -0000 X-SWARE-Spam-Status: No, hits=-2.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,MISSING_MID X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 01 Nov 2010 13:21:43 +0000 From: "mahatma at eu dot by" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/45359] poor -march=native choices for VIA C7 Esther processors X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Keywords: X-Bugzilla-Severity: minor X-Bugzilla-Who: mahatma at eu dot by X-Bugzilla-Status: WAITING X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Date: Mon, 01 Nov 2010 13:21:00 -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 X-SW-Source: 2010-11/txt/msg00018.txt.bz2 Message-ID: <20101101132100.pSixcMkte7uyczMmwm3CBeeUC5Vc9xAt5nZsXMOS5U8@z> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45359 --- Comment #3 from Dzianis Kahanovich 2010-11-01 13:21:40 UTC --- Created attachment 22220 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=22220 native VIA/CentaurHauls (In reply to comment #1) > Why do you think it's a poor choice? This is regression after PR target/44046. Previous behaviour was: sse3 -> "-march=prescott -mtune=generic", now: sse3 -> "-march=pentium-m -mtune=generic". This regression lose sse3 support for C-7 CPU. But in other point, "prescott" as family-15 member, may be (or not) else scheduled, then family-6 clone... Other source of problem - VIA/Centaur CPUs detecting as "Intel" vendor. I believe, Intel support have own reason to make choice sse3 -> pentium-m and lose this sse3, then I suggest to forget this behaviour and add native VIA/CentaurHauls support code. There are 3 point of detection: 1) vendor signature; 2) cache detection: according to Linux kernel code, "detect_caches_amd" behaviour is not vendor-specific and used in kernel also for any x86_64, VIA/Centaur, Transmeta and Cyrix family-5/model-5, but I have no exotic CPUs exclude VIA C-7 in my notebook to test other vendors; 3) model detection - C-7 will be "-march=prescott -mtune=core2" (FIXME if pure "prescott" is better!), also may be fixed c3-2 -mtune=c3 selection (Gentoo Wiki suggest -mtune=generic or -march=c3 to avoid NOPL for some models, but I try to not use variable "generic").