From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1720) id 827863858425; Wed, 5 Jan 2022 20:48:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 827863858425 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="utf-8" From: =?utf-8?b?RnJhbuCkpeCkiG9pcyBEdW1vbnQ=?= To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-6272] libstdc++: Optimize operations on small size hashtable [PR 68303] X-Act-Checkin: gcc X-Git-Author: =?utf-8?q?Fran=C3=A7ois_Dumont?= X-Git-Refname: refs/heads/master X-Git-Oldrev: 194f712f8b7a6a31651f4cf57d49fbf701da5ed6 X-Git-Newrev: e3ef832a9e8d6a950a439e34e576eb4cb202dc48 Message-Id: <20220105204837.827863858425@sourceware.org> Date: Wed, 5 Jan 2022 20:48:37 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Jan 2022 20:48:37 -0000 https://gcc.gnu.org/g:e3ef832a9e8d6a950a439e34e576eb4cb202dc48 commit r12-6272-ge3ef832a9e8d6a950a439e34e576eb4cb202dc48 Author: François Dumont Date: Mon Jan 20 08:17:09 2020 +0100 libstdc++: Optimize operations on small size hashtable [PR 68303] When hasher is identified as slow and the number of elements is limited in the container use a brute-force loop on those elements to look for a given key using the key_equal functor. For the moment the default threshold to consider the container as small is 20. libstdc++-v3/ChangeLog: PR libstdc++/68303 * include/bits/hashtable_policy.h (_Hashtable_hash_traits<_Hash>): New. (_Hash_code_base<>::_M_hash_code(const _Hash_node_value<>&)): New. (_Hashtable_base<>::_M_key_equals): New. (_Hashtable_base<>::_M_equals): Use latter. (_Hashtable_base<>::_M_key_equals_tr): New. (_Hashtable_base<>::_M_equals_tr): Use latter. * include/bits/hashtable.h (_Hashtable<>::__small_size_threshold()): New, use _Hashtable_hash_traits. (_Hashtable<>::find): Loop through elements to look for key if size is lower than __small_size_threshold(). (_Hashtable<>::_M_emplace(true_type, _Args&&...)): Likewise. (_Hashtable<>::_M_insert_unique(_Kt&&, _Args&&, const _NodeGenerator&)): Likewise. (_Hashtable<>::_M_compute_hash_code(const_iterator, const key_type&)): New. (_Hashtable<>::_M_emplace(const_iterator, false_type, _Args&&...)): Use latter. (_Hashtable<>::_M_find_before_node(const key_type&)): New. (_Hashtable<>::_M_erase(true_type, const key_type&)): Use latter. (_Hashtable<>::_M_erase(false_type, const key_type&)): Likewise. * src/c++11/hashtable_c++0x.cc: Include . * testsuite/util/testsuite_performance.h (report_performance): Use 9 width to display memory. * testsuite/performance/23_containers/insert_erase/unordered_small_size.cc: New performance test case. Diff: --- libstdc++-v3/include/bits/hashtable.h | 187 ++++++++++++++++++--- libstdc++-v3/include/bits/hashtable_policy.h | 53 +++++- libstdc++-v3/src/c++11/hashtable_c++0x.cc | 1 + .../insert_erase/unordered_small_size.cc | 125 ++++++++++++++ .../testsuite/util/testsuite_performance.h | 2 +- 5 files changed, 333 insertions(+), 35 deletions(-) diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h index 398102df945..5e1a417f7cd 100644 --- a/libstdc++-v3/include/bits/hashtable.h +++ b/libstdc++-v3/include/bits/hashtable.h @@ -419,6 +419,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _M_uses_single_bucket() const { return _M_uses_single_bucket(_M_buckets); } + static constexpr size_t + __small_size_threshold() noexcept + { + return + __detail::_Hashtable_hash_traits<_Hash>::__small_size_threshold(); + } + __hashtable_alloc& _M_base_alloc() { return *this; } @@ -788,6 +795,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _M_bucket_index(__hash_code __c) const { return __hash_code_base::_M_bucket_index(__c, _M_bucket_count); } + __node_base_ptr + _M_find_before_node(const key_type&); + // Find and insert helper functions and types // Find the node before the one matching the criteria. __node_base_ptr @@ -831,6 +841,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __node_base_ptr _M_get_previous_node(size_type __bkt, __node_ptr __n); + pair + _M_compute_hash_code(const_iterator __hint, const key_type& __k) const; + // Insert node __n with hash code __code, in bucket __bkt if no // rehash (assumes no element with same key already present). // Takes ownership of __n if insertion succeeds, throws otherwise. @@ -1126,7 +1139,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void _M_rehash(size_type __bkt_count, const __rehash_state& __state); }; - // Definitions of class template _Hashtable's out-of-line member functions. template iterator { + if (size() <= __small_size_threshold()) + { + for (auto __it = begin(); __it != end(); ++__it) + if (this->_M_key_equals(__k, *__it._M_cur)) + return __it; + return end(); + } + __hash_code __code = this->_M_hash_code(__k); std::size_t __bkt = _M_bucket_index(__code); return iterator(_M_find_node(__bkt, __k, __code)); @@ -1643,6 +1663,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION find(const key_type& __k) const -> const_iterator { + if (size() <= __small_size_threshold()) + { + for (auto __it = begin(); __it != end(); ++__it) + if (this->_M_key_equals(__k, *__it._M_cur)) + return __it; + return end(); + } + __hash_code __code = this->_M_hash_code(__k); std::size_t __bkt = _M_bucket_index(__code); return const_iterator(_M_find_node(__bkt, __k, __code)); @@ -1855,6 +1883,35 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } #endif + // Find the node before the one whose key compares equal to k. + // Return nullptr if no node is found. + template + auto + _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, + _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>:: + _M_find_before_node(const key_type& __k) + -> __node_base_ptr + { + __node_base_ptr __prev_p = &_M_before_begin; + if (!__prev_p->_M_nxt) + return nullptr; + + for (__node_ptr __p = static_cast<__node_ptr>(__prev_p->_M_nxt); + __p != nullptr; + __p = __p->_M_next()) + { + if (this->_M_key_equals(__k, *__p)) + return __prev_p; + + __prev_p = __p; + } + + return nullptr; + } + // Find the node before the one whose key compares equal to k in the bucket // bkt. Return nullptr if no node is found. template(__args)... }; const key_type& __k = _ExtractKey{}(__node._M_node->_M_v()); + if (size() <= __small_size_threshold()) + { + for (auto __it = begin(); __it != end(); ++__it) + if (this->_M_key_equals(__k, *__it._M_cur)) + // There is already an equivalent node, no insertion + return { __it, false }; + } + __hash_code __code = this->_M_hash_code(__k); size_type __bkt = _M_bucket_index(__code); - if (__node_ptr __p = _M_find_node(__bkt, __k, __code)) - // There is already an equivalent node, no insertion - return std::make_pair(iterator(__p), false); + if (size() > __small_size_threshold()) + if (__node_ptr __p = _M_find_node(__bkt, __k, __code)) + // There is already an equivalent node, no insertion + return { iterator(__p), false }; // Insert the node auto __pos = _M_insert_unique_node(__bkt, __code, __node._M_node); @@ -2031,13 +2097,41 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _Scoped_node __node { this, std::forward<_Args>(__args)... }; const key_type& __k = _ExtractKey{}(__node._M_node->_M_v()); - __hash_code __code = this->_M_hash_code(__k); + auto __res = this->_M_compute_hash_code(__hint, __k); auto __pos - = _M_insert_multi_node(__hint._M_cur, __code, __node._M_node); + = _M_insert_multi_node(__res.first._M_cur, __res.second, + __node._M_node); __node._M_node = nullptr; return __pos; } + template + auto + _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, + _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>:: + _M_compute_hash_code(const_iterator __hint, const key_type& __k) const + -> pair + { + if (size() <= __small_size_threshold()) + { + if (__hint != cend()) + { + for (auto __it = __hint; __it != cend(); ++__it) + if (this->_M_key_equals(__k, *__it._M_cur)) + return { __it, this->_M_hash_code(*__it._M_cur) }; + } + + for (auto __it = cbegin(); __it != __hint; ++__it) + if (this->_M_key_equals(__k, *__it._M_cur)) + return { __it, this->_M_hash_code(*__it._M_cur) }; + } + + return { __hint, this->_M_hash_code(__k) }; + } + template pair { + if (size() <= __small_size_threshold()) + for (auto __it = begin(); __it != end(); ++__it) + if (this->_M_key_equals_tr(__k, *__it._M_cur)) + return { __it, false }; + __hash_code __code = this->_M_hash_code_tr(__k); size_type __bkt = _M_bucket_index(__code); - if (__node_ptr __node = _M_find_node_tr(__bkt, __k, __code)) - return { iterator(__node), false }; + if (size() > __small_size_threshold()) + if (__node_ptr __node = _M_find_node_tr(__bkt, __k, __code)) + return { iterator(__node), false }; _Scoped_node __node { __node_builder_t::_S_build(std::forward<_Kt>(__k), @@ -2172,11 +2272,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _Scoped_node __node{ __node_gen(std::forward<_Arg>(__v)), this }; // Second compute the hash code so that we don't rehash if it throws. - __hash_code __code - = this->_M_hash_code(_ExtractKey{}(__node._M_node->_M_v())); + auto __res = this->_M_compute_hash_code( + __hint, _ExtractKey{}(__node._M_node->_M_v())); auto __pos - = _M_insert_multi_node(__hint._M_cur, __code, __node._M_node); + = _M_insert_multi_node(__res.first._M_cur, __res.second, + __node._M_node); __node._M_node = nullptr; return __pos; } @@ -2239,16 +2340,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _M_erase(true_type /* __uks */, const key_type& __k) -> size_type { - __hash_code __code = this->_M_hash_code(__k); - std::size_t __bkt = _M_bucket_index(__code); + __node_base_ptr __prev_n; + __node_ptr __n; + std::size_t __bkt; + if (size() <= __small_size_threshold()) + { + __prev_n = _M_find_before_node(__k); + if (!__prev_n) + return 0; - // Look for the node before the first matching node. - __node_base_ptr __prev_n = _M_find_before_node(__bkt, __k, __code); - if (!__prev_n) - return 0; + // We found a matching node, erase it. + __n = static_cast<__node_ptr>(__prev_n->_M_nxt); + __bkt = _M_bucket_index(*__n); + } + else + { + __hash_code __code = this->_M_hash_code(__k); + __bkt = _M_bucket_index(__code); + + // Look for the node before the first matching node. + __prev_n = _M_find_before_node(__bkt, __k, __code); + if (!__prev_n) + return 0; + + // We found a matching node, erase it. + __n = static_cast<__node_ptr>(__prev_n->_M_nxt); + } - // We found a matching node, erase it. - __node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt); _M_erase(__bkt, __prev_n, __n); return 1; } @@ -2263,13 +2381,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _M_erase(false_type /* __uks */, const key_type& __k) -> size_type { - __hash_code __code = this->_M_hash_code(__k); - std::size_t __bkt = _M_bucket_index(__code); + std::size_t __bkt; + __node_base_ptr __prev_n; + __node_ptr __n; + if (size() <= __small_size_threshold()) + { + __prev_n = _M_find_before_node(__k); + if (!__prev_n) + return 0; - // Look for the node before the first matching node. - __node_base_ptr __prev_n = _M_find_before_node(__bkt, __k, __code); - if (!__prev_n) - return 0; + // We found a matching node, erase it. + __n = static_cast<__node_ptr>(__prev_n->_M_nxt); + __bkt = _M_bucket_index(*__n); + } + else + { + __hash_code __code = this->_M_hash_code(__k); + __bkt = _M_bucket_index(__code); + + // Look for the node before the first matching node. + __prev_n = _M_find_before_node(__bkt, __k, __code); + if (!__prev_n) + return 0; + + __n = static_cast<__node_ptr>(__prev_n->_M_nxt); + } // _GLIBCXX_RESOLVE_LIB_DEFECTS // 526. Is it undefined if a function in the standard changes @@ -2277,7 +2413,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // We use one loop to find all matching nodes and another to deallocate // them so that the key stays valid during the first loop. It might be // invalidated indirectly when destroying nodes. - __node_ptr __n = static_cast<__node_ptr>(__prev_n->_M_nxt); __node_ptr __n_last = __n->_M_next(); while (__n_last && this->_M_node_equals(*__n, *__n_last)) __n_last = __n_last->_M_next(); diff --git a/libstdc++-v3/include/bits/hashtable_policy.h b/libstdc++-v3/include/bits/hashtable_policy.h index f7a0cea5442..3b60eb9ae72 100644 --- a/libstdc++-v3/include/bits/hashtable_policy.h +++ b/libstdc++-v3/include/bits/hashtable_policy.h @@ -246,6 +246,20 @@ namespace __detail using __unique_keys = __bool_constant<_Unique_keys>; }; + /** + * struct _Hashtable_hash_traits + * + * Important traits for hash tables depending on associated hasher. + * + */ + template + struct _Hashtable_hash_traits + { + static constexpr std::size_t + __small_size_threshold() noexcept + { return std::__is_fast_hash<_Hash>::value ? 0 : 20; } + }; + /** * struct _Hash_node_base * @@ -1105,10 +1119,12 @@ namespace __detail _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true_type /* Has load factor */> { + private: using __hashtable = _Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>; + public: float max_load_factor() const noexcept { @@ -1263,6 +1279,14 @@ namespace __detail const _Hash_node_value<_Value, __cache_hash_code>& __n) const { return _M_hash_code(_ExtractKey{}(__n._M_v())); } + __hash_code + _M_hash_code(const _Hash_node_value<_Value, false>& __n) const + { return _M_hash_code(_ExtractKey{}(__n._M_v())); } + + __hash_code + _M_hash_code(const _Hash_node_value<_Value, true>& __n) const + { return __n._M_hash_code; } + std::size_t _M_bucket_index(__hash_code __c, std::size_t __bkt_count) const { return _RangeHash{}(__c, __bkt_count); } @@ -1641,35 +1665,48 @@ namespace __detail { } bool - _M_equals(const _Key& __k, __hash_code __c, - const _Hash_node_value<_Value, __hash_cached::value>& __n) const + _M_key_equals(const _Key& __k, + const _Hash_node_value<_Value, + __hash_cached::value>& __n) const { static_assert(__is_invocable{}, "key equality predicate must be invocable with two arguments of " "key type"); - return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v())); + return _M_eq()(__k, _ExtractKey{}(__n._M_v())); } template bool - _M_equals_tr(const _Kt& __k, __hash_code __c, - const _Hash_node_value<_Value, - __hash_cached::value>& __n) const + _M_key_equals_tr(const _Kt& __k, + const _Hash_node_value<_Value, + __hash_cached::value>& __n) const { static_assert( __is_invocable{}, "key equality predicate must be invocable with two arguments of " "key type"); - return _S_equals(__c, __n) && _M_eq()(__k, _ExtractKey{}(__n._M_v())); + return _M_eq()(__k, _ExtractKey{}(__n._M_v())); } + bool + _M_equals(const _Key& __k, __hash_code __c, + const _Hash_node_value<_Value, __hash_cached::value>& __n) const + { return _S_equals(__c, __n) && _M_key_equals(__k, __n); } + + template + bool + _M_equals_tr(const _Kt& __k, __hash_code __c, + const _Hash_node_value<_Value, + __hash_cached::value>& __n) const + { return _S_equals(__c, __n) && _M_key_equals_tr(__k, __n); } + bool _M_node_equals( const _Hash_node_value<_Value, __hash_cached::value>& __lhn, const _Hash_node_value<_Value, __hash_cached::value>& __rhn) const { return _S_node_equals(__lhn, __rhn) - && _M_eq()(_ExtractKey{}(__lhn._M_v()), _ExtractKey{}(__rhn._M_v())); + && _M_key_equals(_ExtractKey{}(__lhn._M_v()), __rhn); } void diff --git a/libstdc++-v3/src/c++11/hashtable_c++0x.cc b/libstdc++-v3/src/c++11/hashtable_c++0x.cc index bd6d066abf5..b42f436e9ce 100644 --- a/libstdc++-v3/src/c++11/hashtable_c++0x.cc +++ b/libstdc++-v3/src/c++11/hashtable_c++0x.cc @@ -30,6 +30,7 @@ #include #include #include +#include #include namespace std _GLIBCXX_VISIBILITY(default) diff --git a/libstdc++-v3/testsuite/performance/23_containers/insert_erase/unordered_small_size.cc b/libstdc++-v3/testsuite/performance/23_containers/insert_erase/unordered_small_size.cc new file mode 100644 index 00000000000..ae63c15b5da --- /dev/null +++ b/libstdc++-v3/testsuite/performance/23_containers/insert_erase/unordered_small_size.cc @@ -0,0 +1,125 @@ +// { dg-do run { target c++11 } } + +// Copyright (C) 2021 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// . + +#include +#include +#include +#include +#include + +namespace +{ + const int nb_elements = 20; + const int nb_insts = 150000; + + template + void bench(const char* desc, const std::vector<_ElemType>& elems) + { + using namespace __gnu_test; + + time_counter time; + resource_counter resource; + + std::vector> insts(nb_insts); + for (int j = 0; j != nb_insts; ++j) + insts.emplace_back(); + + start_counters(time, resource); + + for (auto& us : insts) + for (int i = 0; i != nb_elements; ++i) + us.insert(elems[i]); + + stop_counters(time, resource); + + std::ostringstream ostr; + ostr << desc << " 1st insert"; + report_performance(__FILE__, ostr.str().c_str(), time, resource); + + start_counters(time, resource); + + for (auto& us : insts) + for (int i = nb_elements - 1; i >= 0; --i) + { + auto it = us.find(elems[i]); + if (it != us.end()) + us.erase(it); + } + + stop_counters(time, resource); + + ostr.str(""); + ostr << desc << " find/erase"; + report_performance(__FILE__, ostr.str().c_str(), time, resource); + + start_counters(time, resource); + + for (auto& us : insts) + { + us.insert(elems[0]); + for (int i = nb_elements - 1; i >= 0; --i) + us.insert(elems[i]); + } + + stop_counters(time, resource); + ostr.str(""); + ostr << desc << " 2nd insert"; + report_performance(__FILE__, ostr.str().c_str(), time, resource); + + start_counters(time, resource); + + for (auto& us : insts) + for (int j = nb_elements - 1; j >= 0; --j) + us.erase(elems[j]); + + stop_counters(time, resource); + ostr.str(""); + ostr << desc << " erase key "; + report_performance(__FILE__, ostr.str().c_str(), time, resource); + } +} + +int main() +{ + { + std::vector elems; + elems.reserve(nb_elements); + for (int i = 0; i != nb_elements; ++i) + elems.push_back(i); + + bench("std::unordered_set: ", elems); + } + + { + std::vector elems; + { + elems.reserve(nb_elements); + for (int i = 0; i != nb_elements; ++i) + { + std::ostringstream ostr; + ostr << "string #" << i << ' ' << std::string(1000, 'a' + i); + elems.push_back(ostr.str()); + } + } + + bench("std::unordered_set: ", elems); + } + + return 0; +} diff --git a/libstdc++-v3/testsuite/util/testsuite_performance.h b/libstdc++-v3/testsuite/util/testsuite_performance.h index 50d0cb6652f..2e05bef8460 100644 --- a/libstdc++-v3/testsuite/util/testsuite_performance.h +++ b/libstdc++-v3/testsuite/util/testsuite_performance.h @@ -239,7 +239,7 @@ namespace __gnu_test out << std::setw(4) << t.real_time() << "r" << space; out << std::setw(4) << t.user_time() << "u" << space; out << std::setw(4) << t.system_time() << "s" << space; - out << std::setw(8) << r.allocated_memory() << "mem" << space; + out << std::setw(9) << r.allocated_memory() << "mem" << space; out << std::setw(4) << r.hard_page_fault() << "pf" << space; out << std::endl;