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[69.118.112.187]) by smtp.gmail.com with ESMTPSA id f1-20020a05620a408100b006bbd0ae9c05sm13811852qko.130.2022.09.06.17.45.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Sep 2022 17:45:47 -0700 (PDT) From: Patrick Palka To: gcc-patches@gcc.gnu.org Cc: libstdc++@gcc.gnu.org, Patrick Palka Subject: [PATCH 2/2] libstdc++: Optimize is_reference Date: Tue, 6 Sep 2022 20:45:42 -0400 Message-Id: <20220907004542.288365-2-ppalka@redhat.com> X-Mailer: git-send-email 2.37.3.518.g79f2338b37 In-Reply-To: <20220907004542.288365-1-ppalka@redhat.com> References: <20220907004542.288365-1-ppalka@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-14.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE 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: Instead of defining is_reference in terms of is_lvalue_reference and is_rvalue_reference, just define it directly. Tested on x86_64-pc-linux-gnu, does this look OK for trunk? This reduces memory usage of join.cc by 1%. libstdc++-v3/ChangeLog: * include/std/type_traits (is_reference): Make the primary template derive from false_type. Define two partial specializations that derive from true_type. --- libstdc++-v3/include/std/type_traits | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index b83e7257a9f..94e73eafd2f 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -611,8 +611,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION /// is_reference template struct is_reference - : public __or_, - is_rvalue_reference<_Tp>>::type + : public false_type + { }; + + template + struct is_reference<_Tp&> + : public true_type + { }; + + template + struct is_reference<_Tp&&> + : public true_type { }; /// is_arithmetic -- 2.37.3.518.g79f2338b37