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 CBCE73858297 for ; Tue, 8 Nov 2022 13:47:48 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org CBCE73858297 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=1667915268; 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: in-reply-to:in-reply-to:references:references; bh=RozO4njSZYF56VWk41Wux/YbhFOpqOIDwXBJTilfxac=; b=Nx0Ke9Z/xA76/slzJPPCPmGximpX/PoK8gMP0zU6WdkgcABlSmWvxz7ZLG/iGv9FZVTbbB wq4Y5cRoo9puyTH2e0WJ6q3auGyzYLQEnkPwPNIsmI2LzRSf81tiI+x306HN7GqusEYkxr pYgD73v3VA/IXS50rsxyJictwu0xBos= Received: from mail-yb1-f198.google.com (mail-yb1-f198.google.com [209.85.219.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-616-RqBcQ0hwOoi5pF-LtaO0ww-1; Tue, 08 Nov 2022 08:47:47 -0500 X-MC-Unique: RqBcQ0hwOoi5pF-LtaO0ww-1 Received: by mail-yb1-f198.google.com with SMTP id l188-20020a2525c5000000b006cbcff0ab41so14106190ybl.4 for ; Tue, 08 Nov 2022 05:47:47 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=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=RozO4njSZYF56VWk41Wux/YbhFOpqOIDwXBJTilfxac=; b=H5ejPhc36J6S0sXefVh19Ue8x3/UTbThVUEy2VNLmAOpaulCQZMTyqyVrvn0uWDkWc 4xiT0W81xTvUK8FbzwScruieS3Eo1ptu8CB1X7GeQLpxt7nK5SPCk9BDaGpCimtRkcrh XlWwUzOjIhfKYwnq7bSif1uz4BXgSR79f8TwojP2VZZH83lG9yqK3wYjODnOZt7T4ZED eJB9Z3JUp9lbhbweDUZxalYPOnB9lDDNhldkLbFKLe417xfxpi35U65mQcyyrKp6Tald WpCfhtJUj6wMcYzroEzCsFRTMUbCxO6qaaevBNBa6o9vxRMOmZoiYaKvTAOLANiFMHyn +h6A== X-Gm-Message-State: ACrzQf0q6bNS78D6X9DTaHcaXBSOCinZem1LlUQKfq1RG1S4LJXHvABk Gh38Bqt2x6ULHiGnllzUZn3t5prPHk31hvV9kx0UQ66dsQdS71YbKFzZZHUJKyOpduE5vTbAHHN rKryknZmobzBHkPq6H/d2hmZA4MGxNkMLxg== X-Received: by 2002:a81:1c49:0:b0:368:8355:3e98 with SMTP id c70-20020a811c49000000b0036883553e98mr54589145ywc.154.1667915266958; Tue, 08 Nov 2022 05:47:46 -0800 (PST) X-Google-Smtp-Source: AMsMyM6zAsAhRzjRGAfyClGBoDxu8DBtaMokmmIb6jokL2qOWfU3ERX9NXowwNxgGhCoEyvQTllIOXmD2IOx/Vu3eWE= X-Received: by 2002:a81:1c49:0:b0:368:8355:3e98 with SMTP id c70-20020a811c49000000b0036883553e98mr54589126ywc.154.1667915266670; Tue, 08 Nov 2022 05:47:46 -0800 (PST) MIME-Version: 1.0 References: <20221013123649.474497-1-aldyh@redhat.com> In-Reply-To: From: Aldy Hernandez Date: Tue, 8 Nov 2022 14:47:35 +0100 Message-ID: Subject: Re: [PATCH] [PR24021] Implement PLUS_EXPR range-op entry for floats. To: Jakub Jelinek Cc: GCC patches , Andrew MacLeod X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-5.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,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 Tue, Nov 8, 2022 at 2:25 PM Jakub Jelinek wrote: > > On Tue, Nov 08, 2022 at 02:06:58PM +0100, Aldy Hernandez wrote: > > + gcc_checking_assert (!r.nan_signbit_p (sign1)); > > + if (op1_nan && op2_nan) > > + { > > + // If boths signs agree, we could use that sign, but IEEE754 > > + // does not guarantee this for a binary operator. The x86_64 > > + // architure does keep the common known sign, but further tests > > + // are needed to see if other architectures do the same (i387 > > + // long double, ARM/aarch64, PowerPC, s390,{,x}, RSICV, etc). > > s/RSICV/RISCV/ > > > + // In the meantime, keep sign VARYING. > > + ; > > + } > > + else if (op1_nan) > > + { > > + if (op1.nan_signbit_p (sign1)) > > + r.update_nan (sign1); > > + } > > + else if (op2_nan) > > + { > > + if (op2.nan_signbit_p (sign2)) > > + r.update_nan (sign2); > > + } > > Well, these cases also aren't guaranteed for binary operator. > I think a conforming implementation can say copy the NaN operand > to result and toggle the sign. Or, if the operand would be a sNaN, > it must turn it into a qNaN (don't remember right now if there are > requirements on what it can do with the mantissa which needs to change > for the sNaN -> qNaN difference at least, but whether it can just > generate a canonical qNaN or needs to preserve at least some bits), > but could e.g. clear or toggle the sign of the NaN as well. > Whether there are any such implementations or not is a question. > For the single qNaN operand case, it would surprise me if anybody > bothered to tweak the sign bit in any way, just copying the input > seems simpler to me, but for the sNaN -> qNaN conversion it wouldn't > surprise me that much. Well, perhaps we should just nuke update_nan_sign() altogether, and always keep the sign varying? inline bool propagate_nans (frange &r, const frange &op1, const frange &op2) { if (op1.known_isnan () || op2.known_isnan ()) { r.set_nan (op1.type ()); return true; } return false; } I'm fine either way. The less code the better :). Aldy