From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oo1-xc2c.google.com (mail-oo1-xc2c.google.com [IPv6:2607:f8b0:4864:20::c2c]) by sourceware.org (Postfix) with ESMTPS id D66443858D32 for ; Fri, 2 Jun 2023 12:50:33 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org D66443858D32 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-oo1-xc2c.google.com with SMTP id 006d021491bc7-5584e898a13so2053068eaf.1 for ; Fri, 02 Jun 2023 05:50:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685710233; x=1688302233; h=content-transfer-encoding:cc:to:subject:message-id:date:from :reply-to:in-reply-to:references:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=XwslMKkfdRqqrxyBACkr0LaKQ22f4RO7siHEcCyLgNk=; b=M91jAcpZIHINJ2wU3TjprZ1c49VvP47wr3Hyo3e4iI5GFhzbtpYdjUkwnH84tAxHpm 5pPbRbGFvD7MEqNTiP4vjH+GLvnZHqXXAeMihx4C7Ck+8PjhAtgFay+wF+0cLdbk8Kp/ B4uQwGBUGXN2j7OIXp6UK4iPjsBfs77FXBCJjYVq0ho4jjS/3SofQS0MxJlQGLWB/PrZ 2SXZQds8CXz+L3jA5EkRE89ivJBPw4sQMRFNmEATjh01hBylpORYiRE0I95ouAgTX8xR xAv9rSgQxGsm+Ie8i6tcOrV5krW+Bn3v+AYDKrTMw7rungfLIxVsSxIVWKuq1XLu71RL sNlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685710233; x=1688302233; h=content-transfer-encoding:cc:to:subject:message-id:date:from :reply-to:in-reply-to:references:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=XwslMKkfdRqqrxyBACkr0LaKQ22f4RO7siHEcCyLgNk=; b=ihalsseDQoJmLbKVIcdOZingOlrh6CZKAAjQWXbQJFmfG/NqPVA5TQnK9NN99D6srA cnOvzMZPOk+g5SR6WTgH0v+tO9B9dsaAGx05uVBvN/FF+6Uc8frpMCj+XEjfJDvvihis XmLnjQHErIb334g+hE+RkWB65aaPcN5oTJXH5K7Tp4FzzaMVmGcP15Y02rLwF6KcnSly HaYj6sxSl2vVyIC5aXYipXBZK+u6HkEDzvPvnA44Vzxibg3lehaotAIus6I48DIALh7i /PQ+14h0/bPX35SxiB/LBC9/BUVT75lOVxiJ5dkVTF2kz4bkOLbcX/rtVZhGhN8Z+xkH 5LHw== X-Gm-Message-State: AC+VfDzDjAUSFRJz/KToeVo1gaFDLnGuFFqVXQmVTo2oH7UyagaZ23dj alZsfDVjOXJkvH5/LsdRJE5QOouAG7VBnfOUve0= X-Google-Smtp-Source: ACHHUZ46BdtiIMsIERMEsCLliLhfdPt5ELAwNvVWh76IzoSKG+tz0Uuu+dxbMxK4DkumfbY8FmfmWD5mpGwyy0iGESM= X-Received: by 2002:aca:3d44:0:b0:39a:6685:1e15 with SMTP id k65-20020aca3d44000000b0039a66851e15mr1079395oia.15.1685710233097; Fri, 02 Jun 2023 05:50:33 -0700 (PDT) MIME-Version: 1.0 References: <37f1a111-4637-b5aa-41c6-5bda26c99422@free.fr> In-Reply-To: <37f1a111-4637-b5aa-41c6-5bda26c99422@free.fr> Reply-To: noloader@gmail.com From: Jeffrey Walton Date: Fri, 2 Jun 2023 08:50:15 -0400 Message-ID: Subject: Re: Use-case for _addcarryx_u64() wrapper To: Mason Cc: gcc-help@gcc.gnu.org, Uros Bizjak , Jakub Jelinek , Marc Glisse Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-0.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,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 Fri, Jun 2, 2023 at 8:45=E2=80=AFAM Mason wrote: > > On 01/06/2023 10:40, Uros Bizjak wrote: > [...] > > There is no use case to maintain two > > interleaved carry chains, > > What do you mean by "there is no use-case" ? > Are you saying ADCX/ADOX are useless? The advertised use case for dual addc instructions is big integer operations. I read that somewhere in the Intel docs several years ago. When I benchmarked ADCX/ADOX several years ago, ADCX/ADOX were slower than using a single ADDC. So I stayed with ADDC. Maybe cpu manufacturers have improved things nowadays. Jeff