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X-IronPort-AV: E=McAfee;i="6600,9927,10971"; a="3942952" X-IronPort-AV: E=Sophos;i="6.05,237,1701158400"; d="scan'208";a="3942952" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2024 01:13:31 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,237,1701158400"; d="scan'208";a="23318068" Received: from tassilo.jf.intel.com ([10.54.38.190]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2024 01:13:30 -0800 From: Andi Kleen To: gcc-patches@gnu.org Cc: Andi Kleen Subject: [PATCH v4 5/5] Add documentation for musttail attribute Date: Fri, 2 Feb 2024 01:09:20 -0800 Message-ID: <20240202091322.1898280-6-ak@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240202091322.1898280-1-ak@linux.intel.com> References: <20240202091322.1898280-1-ak@linux.intel.com> MIME-Version: 1.0 Received-SPF: none client-ip=192.198.163.12; envelope-from=ak@linux.intel.com; helo=mgamail.intel.com X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.292, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-Spam-Status: No, score=-13.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_PASS, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE 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: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org gcc/ChangeLog: * doc/extend.texi: Document [[musttail]] --- gcc/doc/extend.texi | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 142e41ab8fbf..866f6c4a9fed 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -9875,6 +9875,22 @@ foo (int x, int y) @code{y} is not actually incremented and the compiler can but does not have to optimize it to just @code{return 42 + 42;}. +@cindex @code{musttail} statement attribute +@item musttail + +The @code{gnu::musttail} or @code{clang::musttail} attribute +can be applied to a return statement that returns the value +of a call to indicate that the call must be a tail call +that does not allocate extra stack space. + +@smallexample +[[gnu::musttail]] return foo(); +@end smallexample + +If the compiler cannot generate a tail call it will generate +an error. Tail calls generally require enabling optimization. +On some targets they may not be supported. + @end table @node Attribute Syntax