From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by sourceware.org (Postfix) with ESMTPS id 2156E3858C39; Fri, 24 Nov 2023 19:45:24 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 2156E3858C39 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=inria.fr Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=inria.fr ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 2156E3858C39 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=192.134.164.104 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1700855126; cv=none; b=MCZVs6R/a1NmQFtiW1iv/eS8MCZIGJ6A091S3paGD263fbjXQEcOMlBnqUc589NWXC/Zx18JSBd2uD1emDtjtWnhaKTQgvTVV1s+ta7rYMNygsSfCSRcQxE6ZeGi9JtiqH+a/EpP2GJ4I0y6iyfLx8b5gVMU9QbIytLLZNFkDkA= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1700855126; c=relaxed/simple; bh=9km7LKlF37BzxntJNNNG8ZIHLajB4g8RWKwvYZBPMTs=; h=DKIM-Signature:Date:From:To:Subject:Message-ID:MIME-Version; b=chgYq9XbH/GbWsmjKoRMarXOsWHl+LMHWM73Pb46gr26d+Kd8LaFaoVODeLj6v44jfwuJ3IZPpKgKEFLC943fJukg/sBJVX2MxqRuJn5KykZPD8r0213T6BEBxg7LlvnajWRqWCCYT23IejSqG/dBiHLp1epyY0s4GIeeP6NwBU= ARC-Authentication-Results: i=1; server2.sourceware.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=inria.fr; s=dc; h=date:from:reply-to:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=r6BP/MCwXSzr/CQKm5XXd7VMVaPfHxxA2AHc9PF9p7k=; b=e6oXbyJpIovp6Cy+srnP4g3UH0fU/ESYS9+v4MNbc2UwElICpn1SvsNo sdtVWpNVfByuY7i2C+F1McbmxsKSoAprxixq3tcnUNOCJJjYyN/NWdGUX YaGn4keFZxtaKuYVRvJNG9tPF8QkxSBXoXQMAaiPfp9MbSJ43AkVVBoE0 s=; Authentication-Results: mail3-relais-sop.national.inria.fr; dkim=none (message not signed) header.i=none; spf=SoftFail smtp.mailfrom=marc.glisse@inria.fr; dmarc=fail (p=none dis=none) d=inria.fr X-IronPort-AV: E=Sophos;i="6.04,224,1695679200"; d="scan'208";a="72520789" Received: from 71.79.12.109.rev.sfr.net (HELO hippo) ([109.12.79.71]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Nov 2023 20:45:22 +0100 Date: Fri, 24 Nov 2023 20:45:21 +0100 (CET) From: Marc Glisse Reply-To: libstdc++@gcc.gnu.org To: libstdc++@gcc.gnu.org cc: gcc-patches@gcc.gnu.org Subject: Re: libstdc++: Speed up push_back In-Reply-To: Message-ID: References: <11345207.nUPlyArG6x@minbar> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE 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 Thu, 23 Nov 2023, Jonathan Wakely wrote: > That's why we need -fsane-operator-new Although the standard forbids it, some of us just provide an inline implementation inline void* operator new(std::size_t n){return malloc(n);} inline void operator delete(void*p)noexcept{free(p);} inline void operator delete(void*p,std::size_t)noexcept{free(p);} (I could certainly add a check to abort if malloc returns 0 or other details, depending on what the application calls for) It used to enable a number of optimizations, for instance in gcc-9 auto f(){ return std::vector(4096); } was optimized to just one call to calloc (someone broke that in gcc-10). Using LTO on libsupc++ is related. I don't know if we want to define "sane" operators new/delete, or just have a flag that promises that we won't try to replace the default ones. -- Marc Glisse