From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from nikam.ms.mff.cuni.cz (nikam.ms.mff.cuni.cz [195.113.20.16]) by sourceware.org (Postfix) with ESMTPS id 4BA4138515F9 for ; Wed, 8 Mar 2023 15:53:44 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 4BA4138515F9 Authentication-Results: sourceware.org; dmarc=fail (p=none dis=none) header.from=ucw.cz Authentication-Results: sourceware.org; spf=none smtp.mailfrom=kam.mff.cuni.cz Received: by nikam.ms.mff.cuni.cz (Postfix, from userid 16202) id 08B8328A09C; Wed, 8 Mar 2023 16:53:42 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ucw.cz; s=gen1; t=1678290823; 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=5zzPm4J690tyjD/f4h93WdR+e0amcuaB87W+e2w5kBY=; b=XM3gRMQf2GWEZi5gcGVwLyj3vy2IvPMJJvJ0OBXWBvHE7mM/1blu07vvss9jl5PMRBqSeI jAcqTZZdKSHeHDaKHfy5PrSnvhoc9Vqp8p0fnYYYXAhA3ZXDGsOGAPTBHjQiHHlXHUHNd0 NSZL/IxSs2gft1cWIr+3p4BF6hIdMhE= Date: Wed, 8 Mar 2023 16:53:42 +0100 From: Jan Hubicka To: Jason Merrill Cc: gcc-patches@gcc.gnu.org Subject: Re: [PATCH RFC] c++: lambda mangling alias issues [PR107897] Message-ID: References: <20230308025945.648936-1-jason@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230308025945.648936-1-jason@redhat.com> X-Spam-Status: No, score=-11.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,GIT_PATCH_0,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,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: > Tested x86_64-pc-linux-gnu. Does this look good, or do we want to factor the > flag clearing into a symtab_node counterpart to cgraph_node::reset? > > -- 8< -- > > In 107897, by the time we are looking at the mangling clash, the > alias has already been removed from the symbol table by analyze_functions, > so we can't look at n->cpp_implicit_alias. So just assume that it's an > alias if it's internal. > > In 108887 the problem is that removing the mangling alias from the symbol > table confuses analyze_functions, because it ended up as first_analyzed > somehow, so it becomes a dangling pointer. Fixed by clearing various flags > to neutralize the alias. > > PR c++/107897 > PR c++/108887 > > gcc/cp/ChangeLog: > > * decl2.cc (record_mangling): Improve symbol table handling. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported. > * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test. > --- > gcc/cp/decl2.cc | 25 +++++-- > .../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70 +++++++++++++++++++ > gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 + > 3 files changed, 91 insertions(+), 5 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C > > diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc > index 387e24542cd..e6e58b08de4 100644 > --- a/gcc/cp/decl2.cc > +++ b/gcc/cp/decl2.cc > @@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning) > = mangled_decls->find_slot_with_hash (id, IDENTIFIER_HASH_VALUE (id), > INSERT); > > - /* If this is already an alias, remove the alias, because the real > + /* If this is already an alias, cancel the alias, because the real > decl takes precedence. */ > if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot)) > - if (symtab_node *n = symtab_node::get (*slot)) > - if (n->cpp_implicit_alias) > + { > + if (symtab_node *n = symtab_node::get (*slot)) > { > - n->remove (); > - *slot = NULL_TREE; > + if (n->cpp_implicit_alias) > + { > + /* Actually removing the node isn't safe if other code is already > + holding a pointer to it, so just neutralize it. */ > + n->remove_from_same_comdat_group (); > + n->analyzed = false; > + n->definition = false; > + n->alias = false; > + n->cpp_implicit_alias = false; We have n->reset () for that which is used in similar situation when frontends overwrites extern inline function by its different offline implementation. reset doesn't call remove_from_same_comdat_group probably because it was never used on anything in comdat group. So I think it would make sense to call n->reset() here and add remove_from_same_comdat_group into that. OK with that change. Honza > + } > } > + else > + /* analyze_functions might have already removed the alias from the > + symbol table if it's internal. */ > + gcc_checking_assert (!TREE_PUBLIC (*slot)); > + > + *slot = NULL_TREE; > + } > > if (!*slot) > *slot = decl; > diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C > new file mode 100644 > index 00000000000..c7946a2be08 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C > @@ -0,0 +1,70 @@ > +// PR c++/108887 > +// { dg-do compile { target c++11 } } > + > +template struct integral_constant { > + static constexpr int value = __v; > +}; > +using false_type = integral_constant; > +template struct __result_of_impl; > +template > +struct __result_of_impl { > + typedef decltype(0) type; > +}; > +template > +struct __invoke_result > + : __result_of_impl {}; > +template > +void __invoke_impl(_Fn __f, _Args... __args) { > + __f(__args...); > +} > +template > +void __invoke_r(_Callable __fn, _Args... __args) { > + using __result = __invoke_result<_Args...>; > + using __type = typename __result::type; > + __invoke_impl<__type>(__fn, __args...); > +} > +struct QString { > + QString(const char *); > +}; > +template class function; > +template struct _Base_manager { > + static _Functor _M_get_pointer(int) { __builtin_abort (); } > +}; > +template class _Function_handler; > +template > +struct _Function_handler<_Res(_ArgTypes...), _Functor> { > + using _Base = _Base_manager<_Functor>; > + static _Res _M_invoke(const int &__functor, _ArgTypes &&...__args) { > + auto __trans_tmp_1 = _Base::_M_get_pointer(__functor); > + __invoke_r<_Res>(__trans_tmp_1, __args...); > + } > +}; > +template > +struct function<_Res(_ArgTypes...)> { > + template > + using _Handler = _Function_handler<_Res(_ArgTypes...), _Functor>; > + template function(_Functor) { > + using _My_handler = _Handler<_Functor>; > + _M_invoker = _My_handler::_M_invoke; > + } > + using _Invoker_type = _Res (*)(const int &, _ArgTypes &&...); > + _Invoker_type _M_invoker; > +}; > +struct QRegularExpression { > + QRegularExpression(QString); > +}; > +struct AbstractAccount { > + void get(function, > + function); > +}; > +struct AbstractTimelineModel { > + AbstractAccount m_account; > +}; > +struct LinkPaginationTimelineModel : AbstractTimelineModel { > + void fillTimeline(); > +}; > +void LinkPaginationTimelineModel::fillTimeline() { > + [] {}; > + m_account.get([](AbstractAccount *) { static QRegularExpression re(""); }, > + [](AbstractAccount *) {}); > +} > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C > index 291e451ca1a..a7cb6c5dece 100644 > --- a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C > @@ -1,4 +1,5 @@ > // { dg-do run { target c++20 } } > +// { dg-additional-options "-flto" { target lto } } (PR107897) > > template > concept C1 = __is_same_as(T, int) > > base-commit: 4f181f9c7ee3efc509d185fdfda33be9018f1611 > -- > 2.31.1 >