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Mon, 16 Oct 2023 09:17:27 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id WLcnCqf/LGUXLQAAMHmgww (envelope-from ) for ; Mon, 16 Oct 2023 09:17:27 +0000 From: Tom de Vries To: gdb-patches@sourceware.org Subject: [PATCH v3 1/4] [gdb/cli] Skip string copy in source_cache::ensure Date: Mon, 16 Oct 2023 11:17:45 +0200 Message-Id: <20231016091748.26247-2-tdevries@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20231016091748.26247-1-tdevries@suse.de> References: <20231016091748.26247-1-tdevries@suse.de> MIME-Version: 1.0 Authentication-Results: smtp-out2.suse.de; none X-Spam-Score: 4.11 X-Spamd-Result: default: False [4.11 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; R_MISSING_CHARSET(2.50)[]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; BROKEN_CONTENT_TYPE(1.50)[]; PREVIOUSLY_DELIVERED(0.00)[gdb-patches@sourceware.org]; RCPT_COUNT_ONE(0.00)[1]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.98)[-0.976]; NEURAL_SPAM_LONG(3.00)[1.000]; MID_CONTAINS_FROM(1.00)[]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-2.81)[99.20%] X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org In function source_cache::ensure we have: ... std::ostringstream output; ... contents = output.str(); ... The last line causes an unnecessary string copy. C++20 allows us to skip it, like this: ... contents = std::move (output).str(); ... Use the more efficient solution. Tested on x86_64-linux. --- gdb/source-cache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gdb/source-cache.c b/gdb/source-cache.c index 77b357cb42b..ae02d2516d9 100644 --- a/gdb/source-cache.c +++ b/gdb/source-cache.c @@ -252,7 +252,7 @@ source_cache::ensure (struct symtab *s) std::istringstream input (contents); std::ostringstream output; highlighter->highlight (input, output, lang_name, fullname); - contents = output.str (); + contents = std::move (output).str (); already_styled = true; } catch (...)