From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by sourceware.org (Postfix) with ESMTPS id 2498F3857039; Sun, 7 Mar 2021 21:30:24 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 2498F3857039 Received: by mail-wm1-x32b.google.com with SMTP id w7so4884072wmb.5; Sun, 07 Mar 2021 13:30:24 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language; bh=OOyykNPrYZmlZD7SbEmuiNHA9+iQI1RfaLzaC/5yd6o=; b=Bbm3GUH1dCg/FBVXqnEBVHQW9teBPix1/h/RRWQE1jt+lbE2TmLZFgw0vB4RcgApbv NS45aHS9zX2Ykw7GX9XpvMz0pZKAwxlAk/29tup2WrDT+6zCT6ZZij6VCAUea2On0Rbq hKXxDLZbZxxBMo2hXRhLbFo+X7rSGKoLVfinAYyHt+Qy4r7uXTH2FfTYCFMen0N8O6iT kNx6uTF3zTJFW5CON0lB9J5PuRX6RHqp6l3qVDpfmwQChcVwz+jlX+6h82wZxlzsfCES uFUuO0PBA6VKqNFh5C6rF/6fHN+C//82C0hTRtILdpHG7aOOnzs8U1lQNW6lryhpTsN0 jArA== X-Gm-Message-State: AOAM531M4eDaHj42lp54CIDnfY8sX7WJQNhM34wfIy1y1mMgZVHS6qw0 4irlYcamyMIDMU//Q+w5dhMEdVaBVJBBZg== X-Google-Smtp-Source: ABdhPJzPKGzJwENjRn9qDc9YGfkLph6X0uY5DxsdzuoVPowXsdoO0vYw4VSEmLMxJZeCQZ+A4Cs/LA== X-Received: by 2002:a1c:1fc6:: with SMTP id f189mr19280987wmf.68.1615152622841; Sun, 07 Mar 2021 13:30:22 -0800 (PST) Received: from ?IPv6:2a01:e0a:1dc:b1c0:398d:18e6:f73b:d295? ([2a01:e0a:1dc:b1c0:398d:18e6:f73b:d295]) by smtp.googlemail.com with ESMTPSA id p16sm17059431wrt.54.2021.03.07.13.30.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 07 Mar 2021 13:30:21 -0800 (PST) Subject: Re: [Bug libstdc++/99402] [10/11 Regression] std::copy creates _GLIBCXX_DEBUG false positive for attempt to subscript a dereferenceable (start-of-sequence) iterator To: "libstdc++@gcc.gnu.org" , gcc-patches References: From: =?UTF-8?Q?Fran=c3=a7ois_Dumont?= Message-ID: Date: Sun, 7 Mar 2021 22:30:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/mixed; boundary="------------7C6410530DD5C2F0718DB397" Content-Language: fr X-Spam-Status: No, score=-10.2 required=5.0 tests=BAYES_00, BODY_8BITS, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libstdc++@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++ mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 07 Mar 2021 21:30:26 -0000 This is a multi-part message in MIME format. --------------7C6410530DD5C2F0718DB397 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Here is the patch to correctly deal with the new __dp_sign_max_size. I prefer to introduce new __can_advance overloads for this to correctly deal with the _Distance_precision in it. _M_valid_range was also ignoring __dp_sign_max_size.     libstdc++: [_GLIBCXX_DEBUG] Fix management of __dp_sign_max_size [PR 99402]     libstdc++-v3/ChangeLog:             PR libstdc++/99402             * include/debug/helper_functions.h (__can_advance(_InputIterator,             const std::pair<_Diff, _Distance_precision>&, int)): New.             (__can_advance(const _Safe_iterator<>&,             const std::pair<_Diff, _Distance_precision>&, int)): New.             * include/debug/macros.h (__glibcxx_check_can_increment_dist): New,             use latter.             (__glibcxx_check_can_increment_range): Adapt to use latter.             (__glibcxx_check_can_decrement_range): Likewise.             * include/debug/safe_iterator.h             (_Safe_iterator<>::_M_can_advance(const std::pair<_Diff, _Distance_precision>&,             int)): New.             (__can_advance(const _Safe_iterator<>&,             const std::pair<_Diff, _Distance_precision>&, int)): New.             * include/debug/safe_iterator.tcc             (_Safe_iterator<>::_M_can_advance(const std::pair<_Diff, _Distance_precision>&,             int)): New.             (_Safe_iterator<>::_M_valid_range(const _Safe_iterator<>&,             std::pair&, bool)): Adapt for             __dp_sign_max_size.             (__copy_move_a): Adapt to use __glibcxx_check_can_increment_dist.             (__copy_move_backward_a): Likewise.             (__equal_aux): Likewise.             * include/debug/stl_iterator.h (__can_advance(const std::reverse_iterator<>&,             const std::pair<_Diff, _Distance_precision>&, int)): New.             (__can_advance(const std::move_iterator<>&,             const std::pair<_Diff, _Distance_precision>&, int)): New.             * testsuite/25_algorithms/copy/debug/99402.cc: New test. Tested under Linux x86_64. Ok to commit ? François --------------7C6410530DD5C2F0718DB397 Content-Type: text/x-patch; charset=UTF-8; name="pr99402.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="pr99402.patch" diff --git a/libstdc++-v3/include/debug/helper_functions.h b/libstdc++-v3/include/debug/helper_functions.h index 513e5460eba..c0144ced979 100644 --- a/libstdc++-v3/include/debug/helper_functions.h +++ b/libstdc++-v3/include/debug/helper_functions.h @@ -291,6 +291,18 @@ namespace __gnu_debug __can_advance(const _Safe_iterator<_Iterator, _Sequence, _Category>&, _Size); + template + _GLIBCXX_CONSTEXPR + inline bool + __can_advance(_InputIterator, const std::pair<_Diff, _Distance_precision>&, int) + { return true; } + + template + bool + __can_advance(const _Safe_iterator<_Iterator, _Sequence, _Category>&, + const std::pair<_Diff, _Distance_precision>&, int); + /** Helper function to extract base iterator of random access safe iterator * in order to reduce performance impact of debug mode. Limited to random * access iterator because it is the only category for which it is possible diff --git a/libstdc++-v3/include/debug/macros.h b/libstdc++-v3/include/debug/macros.h index 0988437046f..9ac52ebd09d 100644 --- a/libstdc++-v3/include/debug/macros.h +++ b/libstdc++-v3/include/debug/macros.h @@ -94,6 +94,12 @@ _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__can_advance(_First, _Size), \ ._M_iterator(_First, #_First) \ ._M_integer(_Size, #_Size)) +#define __glibcxx_check_can_increment_dist(_First,_Dist,_Way) \ + _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__can_advance(_First, _Dist, _Way), \ + _M_message(__gnu_debug::__msg_iter_subscript_oob) \ + ._M_iterator(_First, #_First) \ + ._M_integer(_Way * _Dist.first, #_Dist)) + #define __glibcxx_check_can_increment_range(_First1,_Last1,_First2) \ do \ { \ @@ -105,7 +111,7 @@ _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__can_advance(_First, _Size), \ ._M_iterator(_Last1, #_Last1), \ __FILE__,__LINE__,__PRETTY_FUNCTION__); \ _GLIBCXX_DEBUG_VERIFY_AT_F( \ - __gnu_debug::__can_advance(_First2, __dist.first),\ + __gnu_debug::__can_advance(_First2, __dist, 1), \ _M_message(__gnu_debug::__msg_iter_subscript_oob)\ ._M_iterator(_First2, #_First2) \ ._M_integer(__dist.first), \ @@ -123,7 +129,7 @@ _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__can_advance(_First, _Size), \ ._M_iterator(_Last1, #_Last1), \ __FILE__,__LINE__,__PRETTY_FUNCTION__); \ _GLIBCXX_DEBUG_VERIFY_AT_F( \ - __gnu_debug::__can_advance(_First2, -__dist.first),\ + __gnu_debug::__can_advance(_First2, __dist, -1), \ _M_message(__gnu_debug::__msg_iter_subscript_oob)\ ._M_iterator(_First2, #_First2) \ ._M_integer(-__dist.first), \ diff --git a/libstdc++-v3/include/debug/safe_iterator.h b/libstdc++-v3/include/debug/safe_iterator.h index a10df190969..8e138fd32e5 100644 --- a/libstdc++-v3/include/debug/safe_iterator.h +++ b/libstdc++-v3/include/debug/safe_iterator.h @@ -407,6 +407,12 @@ namespace __gnu_debug bool _M_can_advance(difference_type __n, bool __strict = false) const; + // Can we advance the iterator using @p __dist in @p __way direction. + template + bool + _M_can_advance(const std::pair<_Diff, _Distance_precision>& __dist, + int __way) const; + // Is the iterator range [*this, __rhs) valid? bool _M_valid_range(const _Safe_iterator& __rhs, @@ -958,6 +964,14 @@ namespace __gnu_debug _Size __n) { return __it._M_can_advance(__n); } + template + inline bool + __can_advance(const _Safe_iterator<_Iterator, _Sequence, _Category>& __it, + const std::pair<_Diff, _Distance_precision>& __dist, + int __way) + { return __it._M_can_advance(__dist, __way); } + template _Iterator __base(const _Safe_iterator<_Iterator, _Sequence, diff --git a/libstdc++-v3/include/debug/safe_iterator.tcc b/libstdc++-v3/include/debug/safe_iterator.tcc index 81deb10125b..bc2ef2632d4 100644 --- a/libstdc++-v3/include/debug/safe_iterator.tcc +++ b/libstdc++-v3/include/debug/safe_iterator.tcc @@ -92,22 +92,39 @@ namespace __gnu_debug if (__n == 0) return true; + std::pair __dist = __n < 0 + ? _M_get_distance_from_begin() + : _M_get_distance_to_end(); + if (__n < 0) - { - std::pair __dist = - _M_get_distance_from_begin(); - return __dist.second == __dp_exact - ? __dist.first >= -__n - : !__strict && __dist.first > 0; - } - else - { - std::pair __dist = - _M_get_distance_to_end(); + __n = -__n; + return __dist.second == __dp_exact ? __dist.first >= __n : !__strict && __dist.first > 0; } + + template + template + bool + _Safe_iterator<_Iterator, _Sequence, _Category>:: + _M_can_advance(const std::pair<_Diff, _Distance_precision>& __dist, + int __way) const + { + if (this->_M_singular()) + return false; + + if (__dist.first == 0) + return true; + + std::pair __this_dist = __way < 0 + ? _M_get_distance_from_begin() + : _M_get_distance_to_end(); + + if (__dist.second == __dp_exact && __this_dist.second > __dp_sign) + return __this_dist.first >= __dist.first; + + return __this_dist.first > 0; } template @@ -194,20 +211,15 @@ namespace __gnu_debug switch (__dist.second) { case __dp_equality: - if (__dist.first == 0) + // Assume that this is a valid range; we can't check anything else. return true; - break; - case __dp_sign: - case __dp_exact: + default: // If range is not empty first iterator must be dereferenceable. - if (__dist.first > 0) - return !__check_dereferenceable || _M_dereferenceable(); - return __dist.first == 0; + return __dist.first == 0 + || (__dist.first > 0 + && (!__check_dereferenceable || _M_dereferenceable())); } - - // Assume that this is a valid range; we can't check anything else. - return true; } template @@ -225,9 +237,8 @@ namespace __gnu_debug __dist = std::make_pair(__rhs.base() - this->base(), __dp_exact); // If range is not empty first iterator must be dereferenceable. - if (__dist.first > 0) - return this->_M_dereferenceable(); - return __dist.first == 0; + return __dist.first == 0 + || (__dist.first > 0 && this->_M_dereferenceable()); } } // namespace __gnu_debug @@ -251,7 +262,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_Ite>::__type __dist; __glibcxx_check_valid_range2(__first, __last, __dist); - __glibcxx_check_can_increment(__result, __dist.first); + __glibcxx_check_can_increment_dist(__result, __dist, 1); if (__dist.second > ::__gnu_debug::__dp_equality) return std::__copy_move_a<_IsMove>(__first.base(), __last.base(), @@ -268,7 +279,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_II>::__type __dist; __glibcxx_check_valid_range2(__first, __last, __dist); - __glibcxx_check_can_increment(__result, __dist.first); + __glibcxx_check_can_increment_dist(__result, __dist, 1); if (__dist.second > ::__gnu_debug::__dp_sign && __result._M_can_advance(__dist.first, true)) @@ -290,7 +301,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_IIte>::__type __dist; __glibcxx_check_valid_range2(__first, __last, __dist); - __glibcxx_check_can_increment(__result, __dist.first); + __glibcxx_check_can_increment_dist(__result, __dist, 1); if (__dist.second > ::__gnu_debug::__dp_equality) { @@ -318,7 +329,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_Ite>::__type __dist; __glibcxx_check_valid_range2(__first, __last, __dist); - __glibcxx_check_can_increment(__result, -__dist.first); + __glibcxx_check_can_increment_dist(__result, __dist, -1); if (__dist.second > ::__gnu_debug::__dp_equality) return std::__copy_move_backward_a<_IsMove>( @@ -335,7 +346,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_II>::__type __dist; __glibcxx_check_valid_range2(__first, __last, __dist); - __glibcxx_check_can_increment(__result, -__dist.first); + __glibcxx_check_can_increment_dist(__result, __dist, -1); if (__dist.second > ::__gnu_debug::__dp_sign && __result._M_can_advance(-__dist.first, true)) @@ -358,7 +369,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_IIte>::__type __dist; __glibcxx_check_valid_range2(__first, __last, __dist); - __glibcxx_check_can_increment(__result, -__dist.first); + __glibcxx_check_can_increment_dist(__result, __dist, -1); if (__dist.second > ::__gnu_debug::__dp_equality) { @@ -423,7 +434,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_II1>::__type __dist; __glibcxx_check_valid_range2(__first1, __last1, __dist); - __glibcxx_check_can_increment(__first2, __dist.first); + __glibcxx_check_can_increment_dist(__first2, __dist, 1); if (__dist.second > ::__gnu_debug::__dp_equality) return std::__equal_aux(__first1.base(), __last1.base(), __first2); @@ -438,7 +449,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_II1>::__type __dist; __glibcxx_check_valid_range2(__first1, __last1, __dist); - __glibcxx_check_can_increment(__first2, __dist.first); + __glibcxx_check_can_increment_dist(__first2, __dist, 1); if (__dist.second > ::__gnu_debug::__dp_sign && __first2._M_can_advance(__dist.first, true)) @@ -457,7 +468,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { typename ::__gnu_debug::_Distance_traits<_II1>::__type __dist; __glibcxx_check_valid_range2(__first1, __last1, __dist); - __glibcxx_check_can_increment(__first2, __dist.first); + __glibcxx_check_can_increment_dist(__first2, __dist, 1); if (__dist.second > ::__gnu_debug::__dp_equality) { diff --git a/libstdc++-v3/include/debug/stl_iterator.h b/libstdc++-v3/include/debug/stl_iterator.h index a9dd5b6c08d..edeb42ebe98 100644 --- a/libstdc++-v3/include/debug/stl_iterator.h +++ b/libstdc++-v3/include/debug/stl_iterator.h @@ -52,6 +52,13 @@ namespace __gnu_debug __can_advance(const std::reverse_iterator<_Iterator>& __it, _Size __n) { return __can_advance(__it.base(), -__n); } + template + inline bool + __can_advance(const std::reverse_iterator<_Iterator>& __it, + const std::pair<_Diff, _Distance_precision>& __dist, + int __way) + { return __can_advance(__it.base(), __dist, -__way); } + template inline std::reverse_iterator<_Iterator> __base(const std::reverse_iterator<_Safe_iterator< @@ -101,6 +108,13 @@ namespace __gnu_debug __can_advance(const std::move_iterator<_Iterator>& __it, _Size __n) { return __can_advance(__it.base(), __n); } + template + inline bool + __can_advance(const std::move_iterator<_Iterator>& __it, + const std::pair<_Diff, _Distance_precision>& __dist, + int __way) + { return __can_advance(__it.base(), __dist, __way); } + template inline auto __unsafe(const std::move_iterator<_Iterator>& __it) --------------7C6410530DD5C2F0718DB397--