From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eggs.gnu.org (eggs.gnu.org [IPv6:2001:470:142:3::10]) by sourceware.org (Postfix) with ESMTPS id B2DD03858401 for ; Wed, 31 Jan 2024 20:17:05 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org B2DD03858401 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=linux.intel.com Authentication-Results: sourceware.org; spf=none smtp.mailfrom=linux.intel.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org B2DD03858401 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2001:470:142:3::10 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1706732227; cv=none; b=lG5A8hQRuAsWCNJaalv6l6LBvTgZgk5stHScJZcgv5a4h73WLrCi8OIetYap3ElnRPBX49dd2z7/+aGDVX6s1LljrMMaNubvecsGOnbHNvP2CBnncD53dmlFMX33uKk3yTHIfxYENYp6WWxgAMMfh2J+YYZ0+lREb8pVpeAQdW4= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1706732227; c=relaxed/simple; bh=RwKmGN3m/YYk/mvpDMfXmY9L2RMbq/a/WZnC9MrmK4U=; h=DKIM-Signature:Date:From:To:Subject:Message-ID:MIME-Version; b=tgMkfYSUrqJEkXsDebjo47JH0Otxfo58L4CJIp/iHnRTDbh4BrAvIQcvAqE7u97G93mdrdciO4Wnz0KmdM7QW9+tTdprXXGL7ibhcYuUQFuMp6mjlnacDlsLYzGV6haVkuv0pRr9Duh+1m/ynL5GGMzM4LsQBoFeWhemZgY0Ad4= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from mgamail.intel.com ([198.175.65.10]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rVH15-00066f-JE for gcc-patches@gnu.org; Wed, 31 Jan 2024 15:17:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1706732224; x=1738268224; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=RwKmGN3m/YYk/mvpDMfXmY9L2RMbq/a/WZnC9MrmK4U=; b=VjFHJmE+H5NXXUPt1r83F+c4hpx3H5D+6xhUmlOVskd/ovIXISyKMsjT 1buNLJsNv18uS9G/zoutwBRpHzpOLVYpkOiMShBG5TOhmtKZuEB3fuL9T MCsWjspKTro/8lJwZfURlVzg2243oKCdcmyyO3+U2YRw7wU0PgPeMOc1/ c4n5wtuZLwzTm3CnL3lYjEHwNumKE6EGggww3KKMS8PMzR/Pnm11lCCMT r2ccrEuBBtkl+pn5cOUWcsZFQR5InazGMDmv3ahWkBu/IWQrC9BpG8nJB Kd6EtrCUTRGCx6SFiVezrnSivnziNRZM/SuCInbtF+4Bul+s6ksze2R0X A==; X-IronPort-AV: E=McAfee;i="6600,9927,10969"; a="17098117" X-IronPort-AV: E=Sophos;i="6.05,233,1701158400"; d="scan'208";a="17098117" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2024 12:17:02 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,233,1701158400"; d="scan'208";a="4196958" Received: from tassilo.jf.intel.com (HELO tassilo) ([10.54.38.190]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2024 12:17:00 -0800 Date: Wed, 31 Jan 2024 12:16:59 -0800 From: Andi Kleen To: Marek Polacek Cc: gcc-patches@gnu.org Subject: Re: [PATCH v3 1/5] Improve must tail in RTL backend Message-ID: References: <20240131021808.151575-1-ak@linux.intel.com> <20240131021808.151575-2-ak@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: none client-ip=198.175.65.10; 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=-5.8 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,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 List-Id: > This results in "error: cannot tail-call: cannot tail-call: other reasons". > So the second argument should be "other reasons" only. Yes will fix those. Thanks. > > I notice that if I don't use -O2 I also get "other reasons". But it should be > easy-ish to say "cannot tail-call: optimizations not enabled" or so. It's unfortunately not easy to distinguish. It's not just -O2, but various missing transformations make tree-tailcall not do it its job, and they could depend on other flags. But there might be also other reasons not related to the optimization that makes the tail call fall. I would be uncomfortable reporting the problem is -O2 when it might be something else. The right fix would be to make tree-tailcall not fail with optimization, and for the remaining cases add errors there. But that would make the patch a lot bigger and it's not clear it would improve usability that much. So I opted to just mention the problem in the documentation. -Andi