From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22140 invoked by alias); 29 Sep 2014 17:57:10 -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 22131 invoked by uid 89); 29 Sep 2014 17:57:09 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,KAM_STOCKGEN,RCVD_IN_DNSWL_LOW,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-qa0-f45.google.com Received: from mail-qa0-f45.google.com (HELO mail-qa0-f45.google.com) (209.85.216.45) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Mon, 29 Sep 2014 17:57:08 +0000 Received: by mail-qa0-f45.google.com with SMTP id w8so1563138qac.4 for ; Mon, 29 Sep 2014 10:57:06 -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=/fzMCRVWkcvbIg4aJ7ibqlHO3vWnthX9rxjL/8+nFYs=; b=Vj8fS58AlgUG9jlmkvH8NFjpnAuxcmL5rRPrlOa69SfnMg3rPaycxcBkNonjObk2QX KzH8LcyFqg+ejwEsMlvD7w6jRc9ChBOl9jpsXK8jdWtk8uthXszjCRKcxTxMZ7aUS72I SIqjCuoQAWr+x3rTkO27pTR/F/Dr9z3gMAFaD7QsLADUBt562LHhyCjH3BUB1wRBqA9b i4dQuwo2QOqQ+Cro01TOqMScC3jcsYZEMBLpRBHxePi4aahcLLJ3HxiL0qNosq7DpPt2 ZMmHVkxA1f5Ch8Z6KDa7lW334NYg9nZcgziLs4Sx0jvNZ4wGSqPbL/lP3RP8O5FZZhcV Vvbw== X-Gm-Message-State: ALoCoQlPnyPdDojDnUWgbOEyalXk6YJTw979SH1rOKprUd1PFjGwTLQ+yFwkfgjsOxs5vl7FiV/T MIME-Version: 1.0 X-Received: by 10.140.21.177 with SMTP id 46mr5563164qgl.90.1412013426127; Mon, 29 Sep 2014 10:57:06 -0700 (PDT) Received: by 10.229.26.135 with HTTP; Mon, 29 Sep 2014 10:57:06 -0700 (PDT) In-Reply-To: References: <54062B52.9040706@redhat.com> Date: Mon, 29 Sep 2014 17:57:00 -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: 2014-09/txt/msg02564.txt.bz2 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~