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[192.24.137.251]) by smtp.gmail.com with ESMTPSA id t15-20020a05622a180f00b00399b73d06f0sm5243263qtc.38.2022.10.19.17.06.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Oct 2022 17:06:09 -0700 (PDT) From: Will Hawkins To: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org Cc: Will Hawkins Subject: [PATCH] libstdc++: Refactor implementation of operator+ for std::string Date: Wed, 19 Oct 2022 20:05:59 -0400 Message-Id: <20221020000559.371886-1-whh8b@obs.cr> X-Mailer: git-send-email 2.37.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-13.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Sorry for the delay. Tested on x86-64 Linux. -->8-- After consultation with Jonathan, it seemed like a good idea to create a single function that performed one-allocation string concatenation that could be used by various different version of operator+. This patch adds such a function and calls it from the relevant implementations. libstdc++-v3/ChangeLog: * include/bits/basic_string.h: Add common function that performs single-allocation string concatenation. (__str_cat) Use __str_cat to perform optimized operator+, where relevant. * include/bits/basic_string.tcc:: Remove single-allocation implementation of operator+. Signed-off-by: Will Hawkins --- libstdc++-v3/include/bits/basic_string.h | 66 ++++++++++++++++------ libstdc++-v3/include/bits/basic_string.tcc | 41 -------------- 2 files changed, 49 insertions(+), 58 deletions(-) diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h index cd244191df4..9c2b57f5a1d 100644 --- a/libstdc++-v3/include/bits/basic_string.h +++ b/libstdc++-v3/include/bits/basic_string.h @@ -3485,6 +3485,24 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 _GLIBCXX_END_NAMESPACE_CXX11 #endif + template + _GLIBCXX20_CONSTEXPR + inline _Str + __str_concat(typename _Str::value_type const* __lhs, + typename _Str::size_type __lhs_len, + typename _Str::value_type const* __rhs, + typename _Str::size_type __rhs_len, + typename _Str::allocator_type const& __a) + { + typedef typename _Str::allocator_type allocator_type; + typedef __gnu_cxx::__alloc_traits _Alloc_traits; + _Str __str(_Alloc_traits::_S_select_on_copy(__a)); + __str.reserve(__lhs_len + __rhs_len); + __str.append(__lhs, __lhs_len); + __str.append(__rhs, __rhs_len); + return __str; + } + // operator+ /** * @brief Concatenate two strings. @@ -3494,13 +3512,14 @@ _GLIBCXX_END_NAMESPACE_CXX11 */ template _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR - basic_string<_CharT, _Traits, _Alloc> + inline basic_string<_CharT, _Traits, _Alloc> operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, const basic_string<_CharT, _Traits, _Alloc>& __rhs) { - basic_string<_CharT, _Traits, _Alloc> __str(__lhs); - __str.append(__rhs); - return __str; + typedef basic_string<_CharT, _Traits, _Alloc> _Str; + return std::__str_concat<_Str>(__lhs.c_str(), __lhs.size(), + __rhs.c_str(), __rhs.size(), + __lhs.get_allocator()); } /** @@ -3511,9 +3530,16 @@ _GLIBCXX_END_NAMESPACE_CXX11 */ template _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR - basic_string<_CharT,_Traits,_Alloc> + inline basic_string<_CharT,_Traits,_Alloc> operator+(const _CharT* __lhs, - const basic_string<_CharT,_Traits,_Alloc>& __rhs); + const basic_string<_CharT,_Traits,_Alloc>& __rhs) + { + __glibcxx_requires_string(__lhs); + typedef basic_string<_CharT, _Traits, _Alloc> _Str; + return std::__str_concat<_Str>(__lhs, _Traits::length(__lhs), + __rhs.c_str(), __rhs.size(), + __rhs.get_allocator()); + } /** * @brief Concatenate character and string. @@ -3523,8 +3549,14 @@ _GLIBCXX_END_NAMESPACE_CXX11 */ template _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR - basic_string<_CharT,_Traits,_Alloc> - operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs); + inline basic_string<_CharT,_Traits,_Alloc> + operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs) + { + typedef basic_string<_CharT, _Traits, _Alloc> _Str; + return std::__str_concat<_Str>(__builtin_addressof(__lhs), 1, + __rhs.c_str(), __rhs.size(), + __rhs.get_allocator()); + } /** * @brief Concatenate string and C string. @@ -3538,11 +3570,12 @@ _GLIBCXX_END_NAMESPACE_CXX11 operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, const _CharT* __rhs) { - basic_string<_CharT, _Traits, _Alloc> __str(__lhs); - __str.append(__rhs); - return __str; + __glibcxx_requires_string(__rhs); + typedef basic_string<_CharT, _Traits, _Alloc> _Str; + return std::__str_concat<_Str>(__lhs.c_str(), __lhs.size(), + __rhs, _Traits::length(__rhs), + __lhs.get_allocator()); } - /** * @brief Concatenate string and character. * @param __lhs First string. @@ -3554,11 +3587,10 @@ _GLIBCXX_END_NAMESPACE_CXX11 inline basic_string<_CharT, _Traits, _Alloc> operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs) { - typedef basic_string<_CharT, _Traits, _Alloc> __string_type; - typedef typename __string_type::size_type __size_type; - __string_type __str(__lhs); - __str.append(__size_type(1), __rhs); - return __str; + typedef basic_string<_CharT, _Traits, _Alloc> _Str; + return std::__str_concat<_Str>(__lhs.c_str(), __lhs.size(), + __builtin_addressof(__rhs), 1, + __lhs.get_allocator()); } #if __cplusplus >= 201103L diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc index 710c2dfe030..56114f120ba 100644 --- a/libstdc++-v3/include/bits/basic_string.tcc +++ b/libstdc++-v3/include/bits/basic_string.tcc @@ -605,47 +605,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #else # define _GLIBCXX_STRING_CONSTEXPR #endif - - template - _GLIBCXX20_CONSTEXPR - basic_string<_CharT, _Traits, _Alloc> - operator+(const _CharT* __lhs, - const basic_string<_CharT, _Traits, _Alloc>& __rhs) - { - __glibcxx_requires_string(__lhs); - typedef basic_string<_CharT, _Traits, _Alloc> __string_type; - typedef typename __string_type::size_type __size_type; - typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template - rebind<_CharT>::other _Char_alloc_type; - typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Alloc_traits; - const __size_type __len = _Traits::length(__lhs); - __string_type __str(_Alloc_traits::_S_select_on_copy( - __rhs.get_allocator())); - __str.reserve(__len + __rhs.size()); - __str.append(__lhs, __len); - __str.append(__rhs); - return __str; - } - - template - _GLIBCXX20_CONSTEXPR - basic_string<_CharT, _Traits, _Alloc> - operator+(_CharT __lhs, const basic_string<_CharT, _Traits, _Alloc>& __rhs) - { - typedef basic_string<_CharT, _Traits, _Alloc> __string_type; - typedef typename __string_type::size_type __size_type; - typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template - rebind<_CharT>::other _Char_alloc_type; - typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Alloc_traits; - __string_type __str(_Alloc_traits::_S_select_on_copy( - __rhs.get_allocator())); - const __size_type __len = __rhs.size(); - __str.reserve(__len + 1); - __str.append(__size_type(1), __lhs); - __str.append(__rhs); - return __str; - } - template _GLIBCXX_STRING_CONSTEXPR typename basic_string<_CharT, _Traits, _Alloc>::size_type -- 2.37.3