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 1568F3858281 for ; Tue, 16 Aug 2022 11:34:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 1568F3858281 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-186--6bIW43ZMJWPi0gDlOksSQ-1; Tue, 16 Aug 2022 07:34:00 -0400 X-MC-Unique: -6bIW43ZMJWPi0gDlOksSQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7FB623817A64; Tue, 16 Aug 2022 11:34:00 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.192.41]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0F2FDC15BA6; Tue, 16 Aug 2022 11:33:59 +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 27GBXuOP1272053 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 16 Aug 2022 13:33:57 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 27GBXtiQ1272052; Tue, 16 Aug 2022 13:33:55 +0200 Date: Tue, 16 Aug 2022 13:33:55 +0200 From: Jakub Jelinek To: Richard Biener , gcc-patches@gcc.gnu.org, FX , "Joseph S. Myers" Subject: Re: [PATCH] Implement __builtin_issignaling Message-ID: Reply-To: Jakub Jelinek References: MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 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=-4.2 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, 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: Tue, 16 Aug 2022 11:34:06 -0000 On Mon, Aug 15, 2022 at 03:06:16PM +0200, Jakub Jelinek via Gcc-patches wrote: > 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. So what about like in this incremental patch: --- gcc/builtins.cc.jj 2022-08-16 13:23:04.220103861 +0200 +++ gcc/builtins.cc 2022-08-16 13:32:03.411257574 +0200 @@ -2765,7 +2765,13 @@ expand_builtin_issignaling (tree exp, rt /* Expand the argument yielding a RTX expression. */ rtx temp = expand_normal (arg); - /* If mode doesn't support NaN, always return 0. */ + /* If mode doesn't support NaN, always return 0. + Don't use !HONOR_SNANS (fmode) here, so there is some possibility of + __builtin_issignaling working without -fsignaling-nans. Especially + when -fno-signaling-nans is the default. + On the other side, MODE_HAS_NANS (fmode) is unnecessary, with + -ffinite-math-only even __builtin_isnan or __builtin_fpclassify + fold to 0 or non-NaN/Inf classification. */ if (!HONOR_NANS (fmode)) { emit_move_insn (target, const0_rtx); @@ -9259,6 +9265,12 @@ fold_builtin_classify (location_t loc, t return fold_build2_loc (loc, UNORDERED_EXPR, type, arg, arg); case BUILT_IN_ISSIGNALING: + /* Folding to true for REAL_CST is done in fold_const_call_ss. + Don't use tree_expr_signaling_nan_p (arg) -> integer_one_node + and !tree_expr_maybe_signaling_nan_p (arg) -> integer_zero_node + here, so there is some possibility of __builtin_issignaling working + without -fsignaling-nans. Especially when -fno-signaling-nans is + the default. */ if (!tree_expr_maybe_nan_p (arg)) return omit_one_operand_loc (loc, type, integer_zero_node, arg); return NULL_TREE; > > > 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. Note, that is what the patch does currently (rejecting _Complex {float,double,long double} etc. arguments). Jakub