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 6D58E3864C56 for ; Tue, 28 May 2024 10:30:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 6D58E3864C56 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 6D58E3864C56 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1716892260; cv=none; b=CioR87m1lnvn40/3+FJxzHPGDuyomtDovfXlm0y5dt9HKr1bGze+EecIgrePaQj+8CKYPGQf+l0xTJc0jLlJwh/ATIMzBzlIp8HeRE9WyXjI1ES8+1z37fjSLbP8ska0o55KS+8KU8fZXKY0C6XUJ718Oug4mcrdQr61IespVXk= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1716892260; c=relaxed/simple; bh=xnAa7uMG2ImDGutbV8NKZBiVljNzrj3DDOLmRT1rOBo=; h=DKIM-Signature:MIME-Version:From:Date:Message-ID:Subject:To; b=o+gF6Ghjlv41cK3nYLIMZmP60dyVcxZBqk8Zie5ognBYXfL6rZ/3rg5i3/hqHGCBk8sXB2Mj3k2IJcUsIEOHLJROp6z1cnePejL8JXz+x4797NCi72uRwUQZUiRjFXxJ6koBJFV/1emMUMJnjDWXozjIwnvzVIzg/eJlmoKxTMw= ARC-Authentication-Results: i=1; server2.sourceware.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1716892256; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3A3388dyAKAcpnPv0BpdrzgBgG3Uq+jcrkmWTqnAVvk=; b=N5NmrmMcleRslQR4my3HnYI6WiaXwDR/g8MVbLoPCikRaf42jo+Xce6Myjrb8dl8Zt0Api TBc+PySIU9ctE9coTjJ9FfPUDDpg4ezMJW83YuW0gu1I1+dlitDI9Y+7dD+U+mTt/IxuMF AmITPd7ixyXmhLKB5hQ7Qv4CvhdKf1k= Received: from mail-yb1-f197.google.com (mail-yb1-f197.google.com [209.85.219.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-38-X5HufbHAPiGpDSpZNnC8yQ-1; Tue, 28 May 2024 06:30:54 -0400 X-MC-Unique: X5HufbHAPiGpDSpZNnC8yQ-1 Received: by mail-yb1-f197.google.com with SMTP id 3f1490d57ef6-dee902341c0so1035901276.3 for ; Tue, 28 May 2024 03:30:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716892252; x=1717497052; h=content-transfer-encoding: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=3A3388dyAKAcpnPv0BpdrzgBgG3Uq+jcrkmWTqnAVvk=; b=cVq6DsnbT6OR06thtr0SfrZokuXOvzdhwrxLNQv2gOAENBBZWlwrO7kiKTT0AUJkn8 sbyeSj656EIjdCTfnuxGAkWfBs1nTm1BYAQJUriFr/2OQy3f1ag+9xqYdepg9tSN/e2+ dQGGZICASGafQZ8kCmIyqA8DfZ9sTQjzt6/HjyQAc4TheiY63zs0F+03HyljPrvf0FCC UCfnrS/pSVLFJeM3tuN6T9EMmuiHWoFLM/Tdy+aYxJKZtAlRFhtrQpngcuSp7HaWlEHW NlieLtRsXQPQxtSs+NYO+m2gv6/9IwptuyWLeXLZYi9PzMJOF4lLLRKfHqj+ffhvU//2 MAmA== X-Gm-Message-State: AOJu0YwprK9wYEEnuUYosKtzWuaM4AfutIjb7k1ZoWVc5UHHb43Z5RIn 8YLKnf3SgcsSJzPvCePQ4WKfupEwTS12Vy3SdhDtyGoEaD3rqRhBwSOkXBUsGhVkm5+K9wuCWYP 6A41s/n+Kwki8Npr9M/bVvd3LmGx93pl6KBqP4SzHtlvbtrLrWgjHhtHv6RW0akPEfdgsKAEpFo cWVVH5lHNp4zAVwnY+GquCQm9yrOQ= X-Received: by 2002:a25:874d:0:b0:df7:c087:57a1 with SMTP id 3f1490d57ef6-df7c0876661mr2622344276.51.1716892252036; Tue, 28 May 2024 03:30:52 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH8DhovD14UAzoX2mIwplJEyc7R+gx+ArqxVGs3b2nvev0HRx4IhjJa/m6nry0Y6b4HY3fRFwTHPymFmEJLOF8= X-Received: by 2002:a25:874d:0:b0:df7:c087:57a1 with SMTP id 3f1490d57ef6-df7c0876661mr2622325276.51.1716892251586; Tue, 28 May 2024 03:30:51 -0700 (PDT) MIME-Version: 1.0 References: <305e3002-4ebb-4f07-91f3-10a29ec7fc70@gmail.com> <610e3afa-8a8a-400d-882e-41ec186d67f6@gmail.com> In-Reply-To: <610e3afa-8a8a-400d-882e-41ec186d67f6@gmail.com> From: Jonathan Wakely Date: Tue, 28 May 2024 11:30:35 +0100 Message-ID: Subject: Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings To: =?UTF-8?Q?Fran=C3=A7ois_Dumont?= Cc: "libstdc++" , gcc-patches X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,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 List-Id: On Mon, 27 May 2024 at 05:37, Fran=C3=A7ois Dumont w= rote: > > Here is a new version working also in C++98. Can we use a different solution that doesn't involve an explicit template argument list for that __uninitialized_fill_n_a call? -+ this->_M_impl._M_finish =3D std::__uninitialized_fill_n_a ++ this->_M_impl._M_finish =3D ++ std::__uninitialized_fill_n_a + (__start, __n, __value, _M_get_Tp_allocator()); Using _M_fill_initialize solves the problem :-) > > Note that I have this failure: > > FAIL: 23_containers/vector/types/1.cc -std=3Dgnu++98 (test for excess er= rors) > > but it's already failing on master, my patch do not change anything. Yes, that's been failing for ages. > > Tested under Linux x64, > > still ok to commit ? > > Fran=C3=A7ois > > On 24/05/2024 16:17, Jonathan Wakely wrote: > > On Thu, 23 May 2024 at 18:38, Fran=C3=A7ois Dumont wrote: > >> > >> On 23/05/2024 15:31, Jonathan Wakely wrote: > >>> On 23/05/24 06:55 +0200, Fran=C3=A7ois Dumont wrote: > >>>> As explained in this email: > >>>> > >>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html > >>>> > >>>> I experimented -Wfree-nonheap-object because of my enhancements on > >>>> algos. > >>>> > >>>> So here is a patch to extend the usage of the _Guard type to other > >>>> parts of vector. > >>> Nice, that fixes the warning you were seeing? > >> Yes ! I indeed forgot to say so :-) > >> > >> > >>> We recently got a bug report about -Wfree-nonheap-object in > >>> std::vector, but that is coming from _M_realloc_append which already > >>> uses the RAII guard :-( > >>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D115016 > >> Note that I also had to move call to __uninitialized_copy_a before > >> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-obje= ct > >> warn. But _M_realloc_append is already doing potentially throwing > >> operations before assigning this->_M_impl so it must be something else= . > >> > >> Though it made me notice another occurence of _Guard in this method. N= ow > >> replaced too in this new patch. > >> > >> libstdc++: Use RAII to replace try/catch blocks > >> > >> Move _Guard into std::vector declaration and use it to guard all > >> calls to > >> vector _M_allocate. > >> > >> Doing so the compiler has more visibility on what is done with t= he > >> pointers > >> and do not raise anymore the -Wfree-nonheap-object warning. > >> > >> libstdc++-v3/ChangeLog: > >> > >> * include/bits/vector.tcc (_Guard): Move all the nested > >> duplicated class... > >> * include/bits/stl_vector.h (_Guard_alloc): ...here. > >> (_M_allocate_and_copy): Use latter. > >> (_M_initialize_dispatch): Likewise and set _M_finish fir= st > >> from the result > >> of __uninitialize_fill_n_a that can throw. > >> (_M_range_initialize): Likewise. > >> > >>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h > >>>> b/libstdc++-v3/include/bits/stl_vector.h > >>>> index 31169711a48..4ea74e3339a 100644 > >>>> --- a/libstdc++-v3/include/bits/stl_vector.h > >>>> +++ b/libstdc++-v3/include/bits/stl_vector.h > >>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER > >>>> clear() _GLIBCXX_NOEXCEPT > >>>> { _M_erase_at_end(this->_M_impl._M_start); } > >>>> > >>>> + private: > >>>> + // RAII guard for allocated storage. > >>>> + struct _Guard > >>> If it's being defined at class scope instead of locally in a member > >>> function, I think a better name would be good. Maybe _Ptr_guard or > >>> _Dealloc_guard or something. > >> _Guard_alloc chosen. > >>>> + { > >>>> + pointer _M_storage; // Storage to deallocate > >>>> + size_type _M_len; > >>>> + _Base& _M_vect; > >>>> + > >>>> + _GLIBCXX20_CONSTEXPR > >>>> + _Guard(pointer __s, size_type __l, _Base& __vect) > >>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect) > >>>> + { } > >>>> + > >>>> + _GLIBCXX20_CONSTEXPR > >>>> + ~_Guard() > >>>> + { > >>>> + if (_M_storage) > >>>> + _M_vect._M_deallocate(_M_storage, _M_len); > >>>> + } > >>>> + > >>>> + _GLIBCXX20_CONSTEXPR > >>>> + pointer > >>>> + _M_release() > >>>> + { > >>>> + pointer __res =3D _M_storage; > >>>> + _M_storage =3D 0; > >>> I don't think the NullablePointer requirements include assigning 0, > >>> only from nullptr, which isn't valid in C++98. > >>> > >>> https://en.cppreference.com/w/cpp/named_req/NullablePointer > >>> > >>> Please use _M_storage =3D pointer() instead. > >> I forgot about user fancy pointer, fixed. > >> > >> > >>>> + return __res; > >>>> + } > >>>> + > >>>> + private: > >>>> + _Guard(const _Guard&); > >>>> + }; > >>>> + > >>>> protected: > >>>> /** > >>>> * Memory expansion handler. Uses the member allocation > >>>> function to > >>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER > >>>> _M_allocate_and_copy(size_type __n, > >>>> _ForwardIterator __first, _ForwardIterator __last) > >>>> { > >>>> - pointer __result =3D this->_M_allocate(__n); > >>>> - __try > >>>> - { > >>>> - std::__uninitialized_copy_a(__first, __last, __result, > >>>> - _M_get_Tp_allocator()); > >>>> - return __result; > >>>> - } > >>>> - __catch(...) > >>>> - { > >>>> - _M_deallocate(__result, __n); > >>>> - __throw_exception_again; > >>>> - } > >>>> + _Guard __guard(this->_M_allocate(__n), __n, *this); > >>>> + std::__uninitialized_copy_a > >>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator()= ); > >>>> + return __guard._M_release(); > >>>> } > >>>> > >>>> > >>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER > >>>> // 438. Ambiguity in the "do the right thing" clause > >>>> template > >>>> void > >>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_t= ype) > >>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value, > >>>> __true_type) > >>>> { > >>>> - this->_M_impl._M_start =3D _M_allocate(_S_check_init_len( > >>>> - static_cast(__n), _M_get_Tp_allocator())); > >>>> - this->_M_impl._M_end_of_storage =3D > >>>> - this->_M_impl._M_start + static_cast(__n); > >>>> - _M_fill_initialize(static_cast(__n), __value); > >>> Please fix the comment on _M_fill_initialize if you're removing the > >>> use of it here. > >> Already done in this initial patch proposal, see below. > >> > >>>> + const size_type __n =3D static_cast(__int_n); > >>>> + _Guard __guard(_M_allocate(_S_check_init_len( > >>>> + __n, _M_get_Tp_allocator())), __n, *this); > >>> I think this would be easier to read if the _S_check_init_len call wa= s > >>> done first, and maybe the allocation too, since we are going to need = a > >>> local __start later anyway. So maybe like this: > >>> > >>> template > >>> void > >>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_t= ype) > >>> { > >>> const size_type __n =3D static_cast(__ni); > >>> pointer __start =3D _M_allocate(_S_check_init_len(__n), > >>> _M_get_Tp_allocator()); > >>> _Guard __guard(__start, __n, *this); > >>> this->_M_impl._M_start =3D __start; > >>> _M_fill_initialize(__n, __value); > >>> this->_M_impl._M_end_of_storage =3D __start + __n; > >>> (void) __guard._M_release(); > >>> } > >>> > >>> Or inline the __uninitialized_fill_n_a call if you want to (but then > >>> fix the comment on _M_fill_initialize). Inlining it does make this > >>> function more consistent with the next one, which calls > >>> __uninitialized_copy_a directly. > >> Yes, this is why I called __uninitialized_fill_n_a instead and also to > >> do so *before* assigning _M_impl._M_start. > >> > >> > >>>> - // Called by the first initialize_dispatch above and by the > >>>> - // vector(n,value,a) constructor. > >>>> + // Called by the vector(n,value,a) constructor. > >> See, it's here :-) > > Doh! Sorry, I'm not sure how I missed that. > > > >> Ok to commit ? > > OK for trunk, thanks! > >