From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 82579 invoked by alias); 18 Mar 2016 15:33:18 -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 82569 invoked by uid 89); 18 Mar 2016 15:33:18 -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,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=hello! X-HELO: mail-oi0-f42.google.com Received: from mail-oi0-f42.google.com (HELO mail-oi0-f42.google.com) (209.85.218.42) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Fri, 18 Mar 2016 15:33:08 +0000 Received: by mail-oi0-f42.google.com with SMTP id l76so1816018oig.1 for ; Fri, 18 Mar 2016 08:33:07 -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; bh=ZB5Z82aNZoRYPFTovWl0enNWfE+8gm9cYYOMUT0v3tI=; b=T9Jkmv/maMFHLi3EMmJtrjiV0JgCX762dKEXTQbLeBCI9ZejIrZEtkHoZ0ymW541gb rVfuSgIyEXjPTivG5lMb/+bUhJeUAnqj97vTqsVKFOJhbpIVThLj8NhNXmogvxySMuv6 YBhkCtuHLGTOeazzZmORYPt2a8qDAEabVo9sCBURUPUuoxxLNrMS6jUypoTCTW7dkNkS M7l9jul0UX7GdWCx00B923QhBQK6bbJRrMhpPXK9jjgkRtZyiSU5AI3UdHlTTh2NI8DA y4MIQDOTxkrE+I02D31mjC5JNAGVDxMyoT2w/GxzhngIojFJuWMLfW8eRdzTobZYkrqz Ootg== X-Gm-Message-State: AD7BkJIkQ29n2HNJvNsaj2fisjI0IdgqnWwaBLzkV6BbrtZ2YOYNrTEJS2tIP0COuce5iKA8+u8f0Pz9ehV/Cw== MIME-Version: 1.0 X-Received: by 10.202.90.212 with SMTP id o203mr8552267oib.117.1458315185095; Fri, 18 Mar 2016 08:33:05 -0700 (PDT) Received: by 10.60.82.233 with HTTP; Fri, 18 Mar 2016 08:33:04 -0700 (PDT) In-Reply-To: <20160307133434.GQ10006@redhat.com> References: <20160307133434.GQ10006@redhat.com> Date: Fri, 18 Mar 2016 15:46:00 -0000 Message-ID: Subject: Re: [C PATCH] Prevent -Wunused-value warning with __atomic_fetch_* (PR c/69407) From: Uros Bizjak To: Marek Polacek Cc: "gcc-patches@gcc.gnu.org" , "Joseph S. Myers" , Jakub Jelinek , Jonathan Wakely Content-Type: multipart/mixed; boundary=001a113d51b49427be052e5476e3 X-SW-Source: 2016-03/txt/msg01098.txt.bz2 --001a113d51b49427be052e5476e3 Content-Type: text/plain; charset=UTF-8 Content-length: 1434 On Mon, Mar 7, 2016 at 2:34 PM, Marek Polacek wrote: > On Fri, Mar 04, 2016 at 07:17:46PM +0100, Uros Bizjak wrote: >> Hello! >> >> > This is not a regression but I thought I'd post this anyway. Martin reported >> > that we generate -Wunused-value warnings on the attached testcase, which >> > arguable doesn't make sense. Setting TREE_USED suppresses the warning. Since >> > we already compute 'fetch_op' I used that. (This warning doesn't trigger e.g. >> > for __atomic_load/store/compare.) >> > >> > Bootstrapped/regtested on x86_64-linux, ok for trunk or gcc7? >> > >> > 2016-03-04 Marek Polacek >> > >> > PR c/69407 >> > * c-common.c (resolve_overloaded_builtin): Set TREE_USED for the fetch >> > operations. >> > >> > * gcc.dg/atomic-op-6.c: New test. >> >> You can probably revert my workaround [1] that suppressed these >> warnings in libsupc++/guard.cc. > > Ah, thanks for the heads-up, I'll do that once I get the patch in. I have committed the attached revert after bootstrap on x86_64-linux-gnu {,-m32}. There were no warnings when compiling guard.cc. 2016-03-18 Uros Bizjak Revert: 2015-07-02 Uros Bizjak * libsupc++/guard.cc (__test_and_acquire): Use __p after __atomic_load to avoid unused variable warning. (__set_and_release): Use __p after __atomic_store to avoid unused variable warning. 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