From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28365 invoked by alias); 29 May 2013 09:02:25 -0000 Mailing-List: contact crossgcc-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: crossgcc-owner@sourceware.org Received: (qmail 28354 invoked by uid 89); 29 May 2013 09:02:25 -0000 X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,KHOP_THREADED,RCVD_IN_HOSTKARMA_YE,SPF_NEUTRAL,TW_SG autolearn=no version=3.3.1 Received: from sam.nabble.com (HELO sam.nabble.com) (216.139.236.26) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Wed, 29 May 2013 09:02:24 +0000 Received: from tom.nabble.com ([192.168.236.105]) by sam.nabble.com with esmtp (Exim 4.72) (envelope-from ) id 1UhcH1-0002Gp-33 for crossgcc@sourceware.org; Wed, 29 May 2013 02:02:23 -0700 Date: Wed, 29 May 2013 09:02:00 -0000 From: gabx To: crossgcc@sourceware.org Message-ID: In-Reply-To: References: <1369490491980-233249.post@n7.nabble.com> Subject: Re: gcc CXX_FLAGS MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-SW-Source: 2013-05/txt/msg00056.txt.bz2 On Wed, May 29, 2013 at 9:24 AM, Martin Guy-2 [via Sourceware.org] < ml-node+s1504n233506h65@n7.nabble.com> wrote: > On 28 May 2013 19:31, gabx <[hidden email]> > wrote: > > Thank you all for these details. It is my first deep journey in the > > toolchain world, and as described on the ct-ng website, it can quickly > > become a nightmare. > > Not a nightmare. It's just that compilers are complex. cross-compiler > even more so. > > > I guess my CCX_FLAGS is then a non-sense : > > Not nonsense. You just have a super-fast cross-compiler that generates > the same code as a regular one! > > > Which flags would you keep ? > > My toolchain is aimed at building android kernel and rom for the Google > LG > > nexus 4. > > It depends what you are trying to achieve. If it's just a few % extra > speed, try -Os or -O2/-O3. I think the manual says they optimise for > minimum code size or maximum speed without/with large increases in > compile time and code size, respectively. > Beyond telling the compiler the instruction set it can use, which > should correspond to the silicon in your target device, there is only > a few % speed to be had by juggling with magic options, and which help > and which make it worse or produce non-working code depend on the > specific program you are compiling. > > M > > > Thank you Martin. The unique goal of this toolchain is to build android kernel and rom with gcc 4.8 and some optimization flags for the Google LG nexus 4 (armv7-a rev2) -- View this message in context: http://sourceware-org.1504.n7.nabble.com/gcc-CXX-FLAGS-tp233249p233515.html Sent from the Sourceware - crossgcc list mailing list archive at Nabble.com. -- For unsubscribe information see http://sourceware.org/lists.html#faq