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 BA8F23857343 for ; Fri, 21 Oct 2022 07:31:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org BA8F23857343 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=1666337469; h=from:from:reply-to: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=M6r+dBIiSnK2m9Td2k/twDyXtnCjV98nCRow9InZdls=; b=LlkilBE8dNjCBu7nQGfdo+UmP+19RyqbBinOIS+BRdYctT1K4vKX0EtMOVtTMyFO4YARx4 5K2YbNrdL8mX2GgnA11GPr9PSMi9ixxjLdlx42RFaesgxlJR3VHS/o4hyhdOL5qLQWWME6 KcZvBEryzVvshLDJNn8wJgVpzj78/Y8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-501-jI0bXde6PzibRLlZo_CD7Q-1; Fri, 21 Oct 2022 03:30:59 -0400 X-MC-Unique: jI0bXde6PzibRLlZo_CD7Q-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E5529185A79C for ; Fri, 21 Oct 2022 07:30:58 +0000 (UTC) Received: from tucnak.zalov.cz (unknown [10.39.193.252]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A449749BB60; Fri, 21 Oct 2022 07:30:58 +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 29L7UubY3484870 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 21 Oct 2022 09:30:56 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.17.1/8.17.1/Submit) id 29L7UtJY3484869; Fri, 21 Oct 2022 09:30:55 +0200 Date: Fri, 21 Oct 2022 09:30:55 +0200 From: Jakub Jelinek To: Jason Merrill Cc: gcc-patches@gcc.gnu.org Subject: [PATCH] c++, v2: Don't shortcut TREE_CONSTANT vector type CONSTRUCTORs in cxx_eval_constant_expression [PR107295] Message-ID: Reply-To: Jakub Jelinek References: MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 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=-3.7 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 Thu, Oct 20, 2022 at 10:51:14AM -0400, Jason Merrill wrote: > That seems like a bug; for VECTOR_TYPE we should fold even if !changed. > > > Also, the reason for the short-cutting is I think trying to avoid > > allocating a new CONSTRUCTOR when nothing changes and we just create > > GC garbage by it. > > We might limit the shortcut to non-vector types by hoisting the vector check > in reduced_constant_expression_p out of the CONSTRUCTOR_NO_CLEARING > condition: > > > if (CONSTRUCTOR_NO_CLEARING (t)) > > { > > if (TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE) > > /* An initialized vector would have a VECTOR_CST. */ > > return false; > > then we could remove the fold in the shortcut. Ok, so like this? Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2022-10-21 Jakub Jelinek PR c++/107295 * constexpr.cc (reduced_constant_expression_p) : Return false for VECTOR_TYPE CONSTRUCTORs even without CONSTRUCTOR_NO_CLEARING set on them. (cxx_eval_bare_aggregate): If constant but !changed, fold before returning VECTOR_TYPE_P CONSTRUCTOR. (cxx_eval_constant_expression) : Don't fold TREE_CONSTANT CONSTRUCTOR, just return it. * g++.dg/ext/vector42.C: New test. --- gcc/cp/constexpr.cc.jj 2022-10-19 11:20:28.960225787 +0200 +++ gcc/cp/constexpr.cc 2022-10-20 18:43:42.952440364 +0200 @@ -3104,12 +3104,12 @@ reduced_constant_expression_p (tree t) case CONSTRUCTOR: /* And we need to handle PTRMEM_CST wrapped in a CONSTRUCTOR. */ tree field; + if (TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE) + /* An initialized vector would have a VECTOR_CST. */ + return false; if (CONSTRUCTOR_NO_CLEARING (t)) { - if (TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE) - /* An initialized vector would have a VECTOR_CST. */ - return false; - else if (TREE_CODE (TREE_TYPE (t)) == ARRAY_TYPE) + if (TREE_CODE (TREE_TYPE (t)) == ARRAY_TYPE) { /* There must be a valid constant initializer at every array index. */ @@ -4956,8 +4956,14 @@ cxx_eval_bare_aggregate (const constexpr TREE_SIDE_EFFECTS (ctx->ctor) = side_effects_p; } } - if (*non_constant_p || !changed) + if (*non_constant_p) return t; + if (!changed) + { + if (VECTOR_TYPE_P (type)) + t = fold (t); + return t; + } t = ctx->ctor; if (!t) t = build_constructor (type, NULL); @@ -7387,11 +7393,10 @@ cxx_eval_constant_expression (const cons case CONSTRUCTOR: if (TREE_CONSTANT (t) && reduced_constant_expression_p (t)) { - /* Don't re-process a constant CONSTRUCTOR, but do fold it to - VECTOR_CST if applicable. */ + /* Don't re-process a constant CONSTRUCTOR. */ verify_constructor_flags (t); if (TREE_CONSTANT (t)) - return fold (t); + return t; } r = cxx_eval_bare_aggregate (ctx, t, lval, non_constant_p, overflow_p); --- gcc/testsuite/g++.dg/ext/vector42.C.jj 2022-10-20 17:57:42.767848544 +0200 +++ gcc/testsuite/g++.dg/ext/vector42.C 2022-10-20 17:57:42.767848544 +0200 @@ -0,0 +1,12 @@ +// PR c++/107295 +// { dg-do compile { target c++11 } } + +template struct A { + typedef T __attribute__((vector_size (sizeof (int)))) V; +}; +template using B = typename A::V; +template using V = B<4, T>; +using F = V; +constexpr F a = F () + 0.0f; +constexpr F b = F () + (float) 0.0; +constexpr F c = F () + (float) 0.0L; Jakub