From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23466 invoked by alias); 6 Oct 2014 20:43:46 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 23456 invoked by uid 89); 6 Oct 2014 20:43:45 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=AWL,BAYES_00,KAM_STOCKGEN,RCVD_IN_DNSWL_LOW,SPF_PASS,T_RP_MATCHES_RCVD autolearn=no version=3.3.2 X-HELO: mail-qg0-f49.google.com Received: from mail-qg0-f49.google.com (HELO mail-qg0-f49.google.com) (209.85.192.49) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Mon, 06 Oct 2014 20:43:44 +0000 Received: by mail-qg0-f49.google.com with SMTP id a108so4280622qge.8 for ; Mon, 06 Oct 2014 13:43:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=MzHj/a7XcxvCue3RHV24igUd9RAvgww+RHO13XGNP6w=; b=Vn2E36AN0zvjCURQEAqL1XUbbDvu4MqMriqwRK6VobmL4E94j+/0jSPmyI6giZGds+ RR2UrGdXdALcj9GkA/acGOFTaFHvgyTbWqj7AFIkmaNMLozAPK9Qaj5ZHt1yNudEZaHc 7ocxGGz/JRstwgxkj5USwqPNjIckqiDIyyxGndPy/zWRqqNoakqm41uLxDUJi6vkeKWP 4DrOOwVvn4NxFYhRjuUCgt07G6Rizy+mCx/LCIeAGVK/KToEAvUD2ZEXh3Kw5K2vfuYG Rc9D79KfGU/EuGup1PyzXdVAuxbBMRedHfh2jy9zqqs8Ggb13P3FQJ8PTbYgDxbNHtAI xBnA== X-Gm-Message-State: ALoCoQlpaiBj0cMgf3CvhO5AnFFUgyap+zVgThf9c7qeThPZK731v7VVe6WmPPGQl06uE7HkR7kn MIME-Version: 1.0 X-Received: by 10.224.20.9 with SMTP id d9mr33543377qab.7.1412628222464; Mon, 06 Oct 2014 13:43:42 -0700 (PDT) Received: by 10.229.26.135 with HTTP; Mon, 6 Oct 2014 13:43:42 -0700 (PDT) In-Reply-To: References: <54062B52.9040706@redhat.com> Date: Mon, 06 Oct 2014 20:43:00 -0000 Message-ID: Subject: Re: [PATCH x86_64] Optimize access to globals in "-fpie -pie" builds with copy relocations From: Sriraman Tallam To: Richard Henderson Cc: GCC Patches , David Li , Cary Coutant , Ian Lance Taylor , Paul Pluzhnikov Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2014-10/txt/msg00495.txt.bz2 Ping. On Mon, Sep 29, 2014 at 10:57 AM, Sriraman Tallam wrote: > Ping. > > On Fri, Sep 19, 2014 at 2:11 PM, Sriraman Tallam wrote: >> Hi Richard, >> >> I also ran the gcc testsuite with >> RUNTESTFLAGS="--tool_opts=-mcopyrelocs" to check for issues. The only >> test that failed was g++.dg/tsan/default_options.C. It uses -fpie >> -pie and BFD ld to link. Since BFD ld does not support copy >> relocations with -pie, it does not link. I linked with gold to make >> the test pass. >> >> Could you please take another look at this patch? >> >> Thanks >> Sri >> >> On Mon, Sep 8, 2014 at 3:19 PM, Sriraman Tallam wrote: >>> On Tue, Sep 2, 2014 at 1:40 PM, Richard Henderson wrote: >>>> On 06/20/2014 05:17 PM, Sriraman Tallam wrote: >>>>> Index: config/i386/i386.c >>>>> =================================================================== >>>>> --- config/i386/i386.c (revision 211826) >>>>> +++ config/i386/i386.c (working copy) >>>>> @@ -12691,7 +12691,9 @@ legitimate_pic_address_disp_p (rtx disp) >>>>> return true; >>>>> } >>>>> else if (!SYMBOL_REF_FAR_ADDR_P (op0) >>>>> - && SYMBOL_REF_LOCAL_P (op0) >>>>> + && (SYMBOL_REF_LOCAL_P (op0) >>>>> + || (TARGET_64BIT && ix86_copyrelocs && flag_pie >>>>> + && !SYMBOL_REF_FUNCTION_P (op0))) >>>>> && ix86_cmodel != CM_LARGE_PIC) >>>>> return true; >>>>> break; >>>> >>>> This is the wrong place to patch. >>>> >>>> You ought to be adjusting SYMBOL_REF_LOCAL_P, by providing a modified >>>> TARGET_BINDS_LOCAL_P. >>> >>> I have done this in the new attached patch, I added a new function >>> i386_binds_local_p which will check for this and call >>> default_binds_local_p otherwise. >>> >>>> >>>> Note in particular that I believe that you are doing the wrong thing with weak >>>> and COMMON symbols, in that you probably ought not force a copy reloc there. >>> >>> I added an extra check to not do this for WEAK symbols. I also added a >>> check for DECL_EXTERNAL so I believe this will also not be called for >>> COMMON symbols. >>> >>>> >>>> Note the complexity of default_binds_local_p_1, and the fact that all you >>>> really want to modify is >>>> >>>> /* If PIC, then assume that any global name can be overridden by >>>> symbols resolved from other modules. */ >>>> else if (shlib) >>>> local_p = false; >>>> >>>> near the bottom of that function. >>> >>> I did not understand what you mean here? Were you suggesting an >>> alternative way of doing this? >>> >>> Thanks for reviewing >>> Sri >>> >>>> >>>> >>>> r~