From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 0F0843858C5E for ; Mon, 3 Apr 2023 20:06:53 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 0F0843858C5E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680552412; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+230GYs05wGhCN4PxogH2zD5YVk2cn84ihbfWwwdJiw=; b=bCZSQavongvNaABzR4+FhxZheuc28SOivBKvuymntn3ZIU6Fkgq4wcGPaQUpPEooG2xTCH le4Jz7J0YDbgtNIx7j4aIWU7h3F92wsz31p5pxomHP26VaREMFGPckb6l6KKTZdCHyaI34 DvmJv/SGO1wCycOJCqm6HSbz882dg48= Received: from mail-lf1-f70.google.com (mail-lf1-f70.google.com [209.85.167.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-290-xaBY1aLLOm24pn8xUPmO4Q-1; Mon, 03 Apr 2023 16:06:51 -0400 X-MC-Unique: xaBY1aLLOm24pn8xUPmO4Q-1 Received: by mail-lf1-f70.google.com with SMTP id d23-20020a193857000000b004e9d2af9e57so12085165lfj.23 for ; Mon, 03 Apr 2023 13:06:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680552410; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=+230GYs05wGhCN4PxogH2zD5YVk2cn84ihbfWwwdJiw=; b=A+52eajA+qjgc1iv4SjJ1uG6fAhRNqHBo57po/yYvHcnTL++Tt13/QTRvTaI4HJXGY gvxbdMRLi0sstZe/hdxmVRxYJwsa42Klbzuq1AQsYZN/IfhfosTsQ4VOqOHIyIilTEi5 N9C2rCl0dYNGWfuO/LH1z1vOPavsOMH6ErjD7i56cZOnCl9zrcsFAazbeISjIKcXurfD LY9wX56j730htWR9vHYMaY9Ig6UIJEzbE46sS1vWPk7rSpwZ8S0DIs08PbefhFNdvh81 VzVbZ2BwXZCM1/yoh4muYarhCa6vjfn+Y+eX8hyYWOvy/si8AX0tDHY2PcoOPTB+E9mX SO2w== X-Gm-Message-State: AAQBX9ftwHvZ2dnpc657GqV/kgKwgLA4pGxyGnCjt1BnF1mIr0C6kZI+ epwG2jfEC/a5IyGjjSMpWHLRax5L+LRHvQ+0VluQW2HPtQ2P4HR6Xnd2YpqVRSapzjUx6eZn/PV tWVWUz1hMVc5uZZeYrrEnmXYkviR/dR8= X-Received: by 2002:a2e:a0c5:0:b0:298:72a8:c6c4 with SMTP id f5-20020a2ea0c5000000b0029872a8c6c4mr241100ljm.9.1680552410240; Mon, 03 Apr 2023 13:06:50 -0700 (PDT) X-Google-Smtp-Source: AKy350Y8dgCDMjadqZUJaMkStnWOwk6FnIi5tEUGZWXvil9OdJdQ11AoICmPuidsCWsi8nixow7xgfSQ1NODmrXRI3Y= X-Received: by 2002:a2e:a0c5:0:b0:298:72a8:c6c4 with SMTP id f5-20020a2ea0c5000000b0029872a8c6c4mr241097ljm.9.1680552409960; Mon, 03 Apr 2023 13:06:49 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Jonathan Wakely Date: Mon, 3 Apr 2023 21:06:39 +0100 Message-ID: Subject: Re: PR 108846 regression To: =?UTF-8?Q?Fran=C3=A7ois_Dumont?= Cc: "libstdc++" X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-6.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,KAM_SHORT,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Mon, 3 Apr 2023 at 21:00, Fran=C3=A7ois Dumont via Libstdc++ wrote: > > After a full rebuild and run of testsuite based on master I have this > regression: > > FAIL: 23_containers/vector/bool/allocator/copy.cc (test for excess errors= ) > Excess errors: > /home/fdumont/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/bits= /stl_algobase.h:437: > warning: 'void* __builtin_memmove(void*, const void*, long unsigned > int)' writing between 9 and 9223372036854775807 bytes into a region of > size 8 overflows the destination [-Wstringop-overflow=3D] > > It comes from the change related to PR 108846, revision > 822a11a1e642e0abe92a996e7033a5066905a447 > > The compiler seems to have enough info to find out that destination > memory area is 8 bytes large but not enough to see that _Num is 1 and so > never going to call the __builtin_memmove. Maybe a compiler bug. Yes, it's a compiler bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109353 > I'm working on a patch to restore previous code when src and dst pointer > types are the same. How will that avoid the PR 108846 problem of overwriting tail padding? > > But I won't be able to continue my work on it before Wednesday so I > prefer to let you know just in case you would like to fix it before that > and maybe differently. > > Fran=C3=A7ois > >