{"id":2226199,"url":"http://patchwork.ozlabs.org/api/patches/2226199/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhub8n5f78.gcc.gcc-TEST.redi.15.1.6@forge-stage.sourceware.org/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"","list_archive_url":null,"date":"2026-04-22T10:25:15","name":"[v1,06/12] libstdc++: Replace _Hashtable::__fwd_value_for with cast","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"90c3afd373eb167ea233c32a770ec9fe70986284","submitter":{"id":93210,"url":"http://patchwork.ozlabs.org/api/people/93210/?format=json","name":"Jonathan Wakely via Sourceware Forge","email":"forge-bot+redi@forge-stage.sourceware.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/bmm.hhub8n5f78.gcc.gcc-TEST.redi.15.1.6@forge-stage.sourceware.org/mbox/","series":[{"id":500966,"url":"http://patchwork.ozlabs.org/api/series/500966/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500966","date":"2026-04-22T10:25:11","name":"WIP: libstdc++: Refactor hash table code","version":1,"mbox":"http://patchwork.ozlabs.org/series/500966/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2226199/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2226199/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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server2.sourceware.org","From":"Jonathan Wakely via Sourceware Forge\n ","Date":"Wed, 22 Apr 2026 10:25:15 +0000","Subject":"[PATCH v1 06/12] libstdc++: Replace _Hashtable::__fwd_value_for with\n cast","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","To":"gcc-patches mailing list ","Message-ID":"\n ","X-Mailer":"batrachomyomachia","X-Requested-Reviewer":"fdumont","X-Pull-Request-Organization":"gcc","X-Pull-Request-Repository":"gcc-TEST","X-Pull-Request":"https://forge.sourceware.org/gcc/gcc-TEST/pulls/15","References":"\n ","In-Reply-To":"\n ","X-Patch-URL":"\n https://forge.sourceware.org/redi/gcc/commit/1c48e98a81347b41cbe5fdef6d69e886ab029f51","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-To":"gcc-patches mailing list , redi@gcc.gnu.org","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"From: Jonathan Wakely \n\nWe can just use a cast to the appropriate type instead of calling a\nfunction to do it. This gives the compiler less work to compile and\noptimize, and at -O0 avoids a function call per element.\n\nlibstdc++-v3/ChangeLog:\n\n\t* include/bits/hashtable.h (_Hashtable::__fwd_value_for):\n\tRemove.\n\t(_Hashtable::_M_assign): Use static_cast instead of\n\t__fwd_value_for.\n\nReviewed-by: François Dumont \n---\n libstdc++-v3/include/bits/hashtable.h | 14 +++++---------\n 1 file changed, 5 insertions(+), 9 deletions(-)","diff":"diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h\nindex bf6eed7c1c69..f1c30896bcb0 100644\n--- a/libstdc++-v3/include/bits/hashtable.h\n+++ b/libstdc++-v3/include/bits/hashtable.h\n@@ -325,13 +325,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t__node_ptr _M_node;\n };\n \n- template\n-\tstatic constexpr\n-\t__conditional_t::value,\n-\t\t\tconst value_type&, value_type&&>\n-\t__fwd_value_for(value_type& __val) noexcept\n-\t{ return std::move(__val); }\n-\n // Compile-time diagnostics.\n \n // _Hash_code_base has everything protected, so use this derived type to\n@@ -1406,11 +1399,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t if (!__ht._M_before_begin._M_nxt)\n \t return;\n \n+\t using _FromVal = __conditional_t::value,\n+\t\t\t\t\t const value_type&, value_type&&>;\n+\n \t // First deal with the special first node pointed to by\n \t // _M_before_begin.\n \t __node_ptr __ht_n = __ht._M_begin();\n \t __node_ptr __this_n\n-\t = __node_gen(__fwd_value_for<_Ht>(__ht_n->_M_v()));\n+\t = __node_gen(static_cast<_FromVal>(__ht_n->_M_v()));\n \t this->_M_copy_code(*__this_n, *__ht_n);\n \t _M_update_bbegin(__this_n);\n \n@@ -1418,7 +1414,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n \t __node_ptr __prev_n = __this_n;\n \t for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())\n \t {\n-\t\t__this_n = __node_gen(__fwd_value_for<_Ht>(__ht_n->_M_v()));\n+\t\t__this_n = __node_gen(static_cast<_FromVal>(__ht_n->_M_v()));\n \t\t__prev_n->_M_nxt = __this_n;\n \t\tthis->_M_copy_code(*__this_n, *__ht_n);\n \t\tsize_type __bkt = _M_bucket_index(*__this_n);\n","prefixes":["v1","06/12"]}