From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by sourceware.org (Postfix) with ESMTPS id 5BDAE3858C50 for ; Thu, 31 Mar 2022 03:43:08 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5BDAE3858C50 Received: by mail-pl1-x62f.google.com with SMTP id x2so22269117plm.7 for ; Wed, 30 Mar 2022 20:43:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=JgkfRuWhngT1jBDGe/Lgx5oXIcYUfEM4opY/CbPN/kA=; b=3XetvMf4bLzUSUKg2TI8HPqwPNsUXbMHz16y1hSUC1cIcBI7Pr0YkM5LDAZEGY4tDs H9nHRKkeQd7uU7z3m0LzGtkj6mZfkva3lYuqDxE2u+NZh+IXXZUQ+5BqrSSptIUDGEyD 9tp3+OI+AQcxej7/oxNlgnlkt5vlk0WS67tz3bm4P+7ydE5/y7ts4c0Hxa2OtvFBk9ZB 9TqmvTt7/5yn0GNMwZpVCgDoqWjsebrGeaDqVUEfXzNMLAdhnBvdI9Ni+mVMMtYtkin2 TuEqjmL4xVlQLS2t6/0hdyQswaVvyC90gAPiEiOV79gpP0EN+58AJePIY/0ZF9x8DWS9 PN7A== X-Gm-Message-State: AOAM5311AkIgquW3e4U198LvorhLGPylYntoBuszSHoq71UCgyCo0k+J K+ZpMTiEUqXGKD1jOEVB5my8xbR6Ug6f7g== X-Google-Smtp-Source: ABdhPJzwMq6uXs5eXZKuhF+/k6GrWcFHWhvjSNbTWjYuCnEtbmQGfWolUjAXBrtmLD91jtngXVYPpw== X-Received: by 2002:a17:902:bf04:b0:149:c5a5:5323 with SMTP id bi4-20020a170902bf0400b00149c5a55323mr3029174plb.97.1648698187173; Wed, 30 Mar 2022 20:43:07 -0700 (PDT) Received: from google.com ([2620:15c:2ce:200:925f:e947:f685:7815]) by smtp.gmail.com with ESMTPSA id m8-20020a056a00080800b004faa4e113bfsm26473264pfk.154.2022.03.30.20.43.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 20:43:06 -0700 (PDT) Date: Wed, 30 Mar 2022 20:43:02 -0700 From: Fangrui Song To: Adhemerval Zanella Cc: libc-alpha@sourceware.org Subject: Re: [PATCH] Remove fno-unit-at-a-time make variable Message-ID: <20220331034302.rzcu6gllo7ltkhjh@google.com> References: <20220330050729.2176630-1-maskray@google.com> <0295bfe2-2f44-c15e-1628-acaf94fc407c@linaro.org> <20220330162311.pwg52gcrr5vnlabe@google.com> <7e7fdfdc-ddc8-cf5a-0525-f927b4ae1e39@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7e7fdfdc-ddc8-cf5a-0525-f927b4ae1e39@linaro.org> X-Spam-Status: No, score=-20.8 required=5.0 tests=BAYES_00, DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE, USER_IN_DEF_DKIM_WL, USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 31 Mar 2022 03:43:10 -0000 On 2022-03-30, Adhemerval Zanella wrote: > > >On 30/03/2022 13:23, Fangrui Song wrote: >> On 2022-03-30, Adhemerval Zanella wrote: >>> >>> >>> On 30/03/2022 02:07, Fangrui Song wrote: >>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>> is a rough replacement for this legacy option >>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>> >>>> The reordering requirement does not seem to be needed any longer. >>> >>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>> glibc ABI. >>> >>> I am trying to fix without resorting to compiler options. >> >> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >> >> >>        .globl  __GLIBC_2_1_sys_errlist >> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>         .type   __GLIBC_2_1_sys_errlist,@object >>         .size   __GLIBC_2_1_sys_errlist, 1000 >>         .globl  __GLIBC_2_1__sys_errlist >> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>         .type   __GLIBC_2_1__sys_errlist,@object >>         .size   __GLIBC_2_1__sys_errlist, 1000 >> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>         .globl  __GLIBC_2_3_sys_errlist >> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>         .type   __GLIBC_2_3_sys_errlist,@object >>         .size   __GLIBC_2_3_sys_errlist, 1008 >>         .globl  __GLIBC_2_3__sys_errlist >> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>         .type   __GLIBC_2_3__sys_errlist,@object >>         .size   __GLIBC_2_3__sys_errlist, 1008 >> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>         .globl  __GLIBC_2_4_sys_errlist >> >> I do not know whether GCC would reorder these macros. Even yes, >> that'd just change the .symtab entries in the relocatable object file. >> The linker behavior remains the same with reordering. > >It does not seem to, just remove the -fno-unit-at-a-time and issue make >check-abi and you will see that object size for the compat symbols >reference to _sys_err_internal instead of the define compat ones. I see. I think this is a brittle behavior in GNU assembler. Filed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed information. I have created a patch but I know that will not solve glibc's problem :(