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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 86EB93858C55 for ; Mon, 15 Aug 2022 13:06:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 86EB93858C55 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-453-mQvHMKiwMHmZFu_CUU8QIw-1; Mon, 15 Aug 2022 09:06:23 -0400 X-MC-Unique: mQvHMKiwMHmZFu_CUU8QIw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4DD643C0F360; Mon, 15 Aug 2022 13:06:22 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.192.41]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DFD7240CFD0A; Mon, 15 Aug 2022 13:06:21 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.17.1/8.17.1) with ESMTPS id 27FD6IWu1242091 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 15 Aug 2022 15:06:18 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 27FD6G161242090; Mon, 15 Aug 2022 15:06:16 +0200 Date: Mon, 15 Aug 2022 15:06:16 +0200 From: Jakub Jelinek To: Richard Biener Cc: "Joseph S. Myers" , Jeff Law , gcc-patches@gcc.gnu.org, FX Subject: Re: [PATCH] Implement __builtin_issignaling Message-ID: Reply-To: Jakub Jelinek References: MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_NONE, 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 X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 Aug 2022 13:06:28 -0000 On Mon, Aug 15, 2022 at 12:07:38PM +0000, Richard Biener wrote: > Ah, I misread > > +static rtx > +expand_builtin_issignaling (tree exp, rtx target) > +{ > + if (!validate_arglist (exp, REAL_TYPE, VOID_TYPE)) > + return NULL_RTX; > + > + tree arg = CALL_EXPR_ARG (exp, 0); > + scalar_float_mode fmode = SCALAR_FLOAT_TYPE_MODE (TREE_TYPE (arg)); > + const struct real_format *fmt = REAL_MODE_FORMAT (fmode); > + > + /* Expand the argument yielding a RTX expression. */ > + rtx temp = expand_normal (arg); > + > + /* If mode doesn't support NaN, always return 0. */ > + if (!HONOR_NANS (fmode)) > + { > + emit_move_insn (target, const0_rtx); > + return target; I think I can expand on the comment why HONOR_NANS instead of HONOR_SNANS and also add comment to the folding case. > which doesn't use HONOR_SNANS but still HONOR_NANS and thus > -ffinite-math-only. You possibly want MODE_HAS_NANS instead here? But I'm not sure we want this. With -ffast-math/-ffinite-math-only etc., __builtin_isnan or __builtin_fpclassify for NaNs/Infs will just return 0, so it would be strange if __builtin_issignaling didn't. People usually only call __builtin_issignaling when they know they have a NaN, so they want it guarded with __builtin_isnan/__builtin_fpclassify or say <=> unordered. > > That seems like a glibc bug/weird feature in the __MATH_TG macro > > or _Generic. > > When compiled with C++ it is rejected. > > So what about __builtin_issignaling then? Do we want to silently > ignore errors there? I think we should just restrict it to the scalar floating point types. After all, other typegeneric builtins that are or can be used similarly do the same thing. Jakub