From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.1 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id E81C61F954 for ; Wed, 22 Aug 2018 16:14:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726694AbeHVTkW (ORCPT ); Wed, 22 Aug 2018 15:40:22 -0400 Received: from mail-it0-f52.google.com ([209.85.214.52]:52782 "EHLO mail-it0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726550AbeHVTkW (ORCPT ); Wed, 22 Aug 2018 15:40:22 -0400 Received: by mail-it0-f52.google.com with SMTP id d9-v6so3569599itf.2 for ; Wed, 22 Aug 2018 09:14:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=1wRNSRi/EiAMtiWI/8yLIK7D7uzt+m+ph6EYLL1fTPQ=; b=oKN5s26KGzj4SUe1SuhUrqpl5EnVDsLCPP2arvpf2tUWceXZDKd22jKPyjqf1jV56Z CaxEEJU5V7kEHRCJZ4fR/HQvpplq9RYRB5KkKJK2dKkVHcWtNkQ2jk9OrBTXMivj4R2v LjP4xT55Hi0NXBTg4gwWy5PaBM39tj3qP/R3rJZeWr2rr6fnx/fOA4el0bb11cutaAa+ Y2yRw41FLaO2hNc/vRKYvFGWLJzCEuQ5K+nxf19fdPeU1DizYGr2R31phfkrtjvc2plR 32vxDQ5DZD9u1XeHd6fVH1XqAUAMjiCR6yMeD7SfWnd84aRKWYAletzDABOVVVlzFheO MhMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=1wRNSRi/EiAMtiWI/8yLIK7D7uzt+m+ph6EYLL1fTPQ=; b=ADAtPxUMcoq7mKRslefS/BLvd7xpuJn/mOIYxnJ9t54HWDukrrADtpq61KJoNjxgmb anx8qI+WxBN76L33W05I4Z2aohXACXe6vBPyOaQXD46RNLfDM/FpjAVp2yVNTbQbmgcr 9AzjEoHeGvLSC+WocSYh6gHLJKqMFXcLsmEY5PPBbYqpmGCDy8VT0WUA4zYFHcMjMkR9 d8310AXTr1gnfSABjxnAVdorpUvilukDYUsZ/hsu1atBhKjlZKA0pxzDX8tKzIJRUwOU MXCfBJyy1CdtN3NLRL1FM5IGCAIzJ6cP/tPP2eTQh5+fRFKRyplV/23VI7TX9CpR0uqe dfaA== X-Gm-Message-State: APzg51ARYzT87qnLm9WzgV8FCeh5NfAsCYMOVo5/cXllNE+HUgzaj41O QRe6osJJOafOWVurdcGIk28WAbzS7oC8GCdkPRA= X-Google-Smtp-Source: ANB0VdYylvY6qaqSe1p0BBLatDueKGXW8lj+IoB1kzhNi9hmzPPzr8Vy68xfTEmis9E7FxdM5chhQ7kbjhzAisREvpM= X-Received: by 2002:a24:144:: with SMTP id 65-v6mr3598410itk.62.1534954490287; Wed, 22 Aug 2018 09:14:50 -0700 (PDT) MIME-Version: 1.0 References: <1b20b754-987c-a712-2594-235b845bc5d0@gmail.com> <20180821212923.GB24431@sigill.intra.peff.net> <20180822004815.GA535143@genre.crustytoothpaste.net> <20180822030344.GA14684@sigill.intra.peff.net> <20180822053626.GB535143@genre.crustytoothpaste.net> <20180822060735.GA13195@sigill.intra.peff.net> <20180822151703.GB32630@sigill.intra.peff.net> In-Reply-To: From: Duy Nguyen Date: Wed, 22 Aug 2018 18:14:24 +0200 Message-ID: Subject: Re: [ANNOUNCE] Git v2.19.0-rc0 To: Jeff King Cc: Derrick Stolee , =?UTF-8?B?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= , "brian m. carlson" , Junio C Hamano , Git Mailing List Content-Type: text/plain; charset="UTF-8" Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Aug 22, 2018 at 6:08 PM Duy Nguyen wrote: > > On Wed, Aug 22, 2018 at 6:03 PM Jeff King wrote: > > > > On Wed, Aug 22, 2018 at 07:14:42AM -0400, Derrick Stolee wrote: > > > > > The other thing I was going to recommend (and I'll try to test this out > > > myself later) is to see if 'the_hash_algo->rawsz' is being treated as a > > > volatile variable, since it is being referenced through a pointer. Perhaps > > > storing the value locally and then casing on it would help? > > > > I tried various sprinkling of "const" around the declarations to make it > > clear that the values wouldn't change once we saw them. But I couldn't > > detect any difference. At most I think that would let us hoist the "if" > > out of the loop, but gcc still seems unwilling to expand the memcmp when > > there are other branches. > > > > I think if that's the thing we want to have happen, we really do need to > > just write it out on that branch rather than saying "memcmp". > > This reminds me of an old discussion about memcpy() vs doing explicit > compare loop with lots of performance measurements.. Ah found it. Not sure if it is still relevant in light of multiple hash support https://public-inbox.org/git/20110427225114.GA16765@elte.hu/ -- Duy