From patchwork Thu Dec 3 11:35:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 1410345 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=2620:52:3:1:0:246e:9693:128c; helo=sourceware.org; envelope-from=gcc-patches-bounces@gcc.gnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux-mips.org Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4Cmtzz6m0Nz9sW0 for ; Thu, 3 Dec 2020 22:35:11 +1100 (AEDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 2F90D3971818; Thu, 3 Dec 2020 11:35:09 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from cvs.linux-mips.org (eddie.linux-mips.org [148.251.95.138]) by sourceware.org (Postfix) with ESMTP id 274AA3971818 for ; Thu, 3 Dec 2020 11:35:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 274AA3971818 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=linux-mips.org Authentication-Results: sourceware.org; spf=none smtp.mailfrom=macro@linux-mips.org Received: from localhost.localdomain ([127.0.0.1]:34302 "EHLO localhost" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23990827AbgLCLfG6AuCx (ORCPT ); Thu, 3 Dec 2020 12:35:06 +0100 Date: Thu, 3 Dec 2020 11:35:06 +0000 (GMT) From: "Maciej W. Rozycki" To: gcc-patches@gcc.gnu.org Subject: [RFC 6/6] ifcvt: Fall through to NCE if getting the CE condition failed In-Reply-To: Message-ID: References: MIME-Version: 1.0 X-Spam-Status: No, score=-3.2 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, KAM_LAZY_DOMAIN_SECURITY, KHOP_HELO_FCRDNS, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces@gcc.gnu.org Sender: "Gcc-patches" If getting the condition for conditional execution has failed then fall through and try the non-conditional execution approach instead rather than giving up with dead code elimination altogether, for a better code structure if nothing else. The case may well now be that whenever `cond_exec_get_condition' fails `noce_get_condition' will as well, however in that case no change in semantics will result. If they ever diverge, then someone will have to chase this place. gcc/ * ifcvt.c (dead_or_predicable) [!IFCVT_MODIFY_TESTS]: Fall through to the non-conditional execution case if getting the condition for conditional execution has failed. --- gcc/ifcvt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: gcc/gcc/ifcvt.c =================================================================== --- gcc.orig/gcc/ifcvt.c +++ gcc/gcc/ifcvt.c @@ -5134,7 +5134,7 @@ dead_or_predicable (basic_block test_bb, cond = cond_exec_get_condition (jump); if (! cond) - return FALSE; + goto nce; rtx note = find_reg_note (jump, REG_BR_PROB, NULL_RTX); profile_probability prob_val