From patchwork Tue Aug 30 08:36:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Biener X-Patchwork-Id: 831 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:ecc5:0:0:0:0:0 with SMTP id s5csp1756640wro; Tue, 30 Aug 2022 01:37:36 -0700 (PDT) X-Google-Smtp-Source: AA6agR7IWGC1ML1CUzrYNGPwLmJ60f0EIIgP/CKNdM4TKClhD3wv4LeLyNa0xOUc5X5EGSNwlyiz X-Received: by 2002:a05:6402:51cb:b0:448:3f0c:4085 with SMTP id r11-20020a05640251cb00b004483f0c4085mr10073341edd.170.1661848656124; Tue, 30 Aug 2022 01:37:36 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1661848656; cv=none; d=google.com; s=arc-20160816; b=fdrHRNqFCbnK2tvKFT1WdGN8Gb+zd00SYDgEQ2KOIN40CbM7mVgVKi6W9q4VNNXSvi E/ca0hGi/2U1c7m4sRx6w76Gj/jKOHG7ybgGVOfhIImIl2EretApxFBQHi0U7JS/IKUU DDi4EIxkHa6IlGDF8V+LRiKtw0tBZ3Zf70hPfpl+/u2oYeyDkgHHMwqNJor2V1kwHQQY bP44fUeeu3LYlaqa3RzvX8rU4XzkH2aqzwYVIVtkfB7eDaJuHRL31yIo6DdRA62kwPWB V048V73zxYdYjz/gfElI/D2myuME2hnVKTmx8Qzjz0hm9+Kja/Cebx8W6bX43fcwn6WC XUCQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:sender:errors-to:reply-to:from:list-subscribe:list-help :list-post:list-archive:list-unsubscribe:list-id:precedence :mime-version:user-agent:subject:to:date:dmarc-filter:delivered-to :dkim-signature:dkim-filter; bh=9DD6/o1lSGJRHjIGpSOc77uC2ABNIX8ZJaKSOV+9Sgo=; b=ow3a3SM/dnMVshNUVtaBsq9TLJNHc+m+PozwGLh78N3PCzcS4f6sv2Eac2LT2d9R8y U8tQHReZGaJF6RpvXELo7Gjdrlv8QV0mxbWyb6qV75X7gYQ6j/fjHeEf/2HB4nsUVnTA APeZdKUfEQHAbk422jvScUjunYMQBk9h92423NeWN6p+/ZXjgG7+hJ/xL3YBIgEwqxEd dxNDMBDdzipnDyLn6UfkOCFQrCd1AE9KR5o1PmXQF26kwYwhy+Du60VHNYI44sa/OO+A 9ycA38KDxHDTlqeMfyMOc1GHoOqnl/5CzHFSFOxjrNwf4ZtA7JT9d6JXGzsRtbhgTZBt tXbQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gcc.gnu.org header.s=default header.b="FG/L9uxH"; spf=pass (google.com: domain of gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org designates 8.43.85.97 as permitted sender) smtp.mailfrom="gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gnu.org Received: from sourceware.org (ip-8-43-85-97.sourceware.org. [8.43.85.97]) by mx.google.com with ESMTPS id e18-20020a056402191200b004486942c312si5468553edz.571.2022.08.30.01.37.35 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Aug 2022 01:37:36 -0700 (PDT) Received-SPF: pass (google.com: domain of gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org designates 8.43.85.97 as permitted sender) client-ip=8.43.85.97; Authentication-Results: mx.google.com; dkim=pass header.i=@gcc.gnu.org header.s=default header.b="FG/L9uxH"; spf=pass (google.com: domain of gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org designates 8.43.85.97 as permitted sender) smtp.mailfrom="gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=gnu.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id DAA7C39960F0 for ; Tue, 30 Aug 2022 08:37:29 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DAA7C39960F0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1661848649; bh=9DD6/o1lSGJRHjIGpSOc77uC2ABNIX8ZJaKSOV+9Sgo=; h=Date:To:Subject:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=FG/L9uxHuABF4wSftrUFrNWeCkdzvi8A8DlmmqpU/E1fEGwUzIkaBAJJP+fzxOdtm riZjtpC+ySRk1b9SIBTHQxdP1OJxavJD/K/3hFez2Xqc5fsjnpW6nJsQevSKa7wp+u op8TDDX5TzsQHZ1xQ1DDmWHwndCxvPXRvrqaScxI= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by sourceware.org (Postfix) with ESMTPS id E2C773AA88E0 for ; Tue, 30 Aug 2022 08:36:42 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E2C773AA88E0 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id EC5B821DAC for ; Tue, 30 Aug 2022 08:36:40 +0000 (UTC) Received: from wotan.suse.de (wotan.suse.de [10.160.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id E784A2C141 for ; Tue, 30 Aug 2022 08:36:40 +0000 (UTC) Date: Tue, 30 Aug 2022 08:36:39 +0000 (UTC) To: gcc-patches@gcc.gnu.org Subject: [PATCH] Use reachability analysis to improve uninit diagnostic User-Agent: Alpine 2.22 (LSU 394 2020-01-19) MIME-Version: 1.0 X-Spam-Status: No, score=-10.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, MISSING_MID, SPF_HELO_NONE, SPF_PASS, 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: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Richard Biener via Gcc-patches From: Richard Biener Reply-To: Richard Biener Errors-To: gcc-patches-bounces+ouuuleilei=gmail.com@gcc.gnu.org Sender: "Gcc-patches" Message-Id: <20220830083729.DAA7C39960F0@sourceware.org> X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1742574616438851228?= X-GMAIL-MSGID: =?utf-8?q?1742574616438851228?= This patch does what the comment in uninit diagnostic suggests. When the value-numbering run done without optimizing figures there's a fallthru path, consider blocks on it as always executed. Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed. * tree-ssa-uninit.cc (warn_uninitialized_vars): Pre-compute the set of fallthru reachable blocks from function entry and use that to determine wlims.always_executed. --- gcc/tree-ssa-uninit.cc | 47 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 9 deletions(-) diff --git a/gcc/tree-ssa-uninit.cc b/gcc/tree-ssa-uninit.cc index 0bd567f237c..c25fbe6381e 100644 --- a/gcc/tree-ssa-uninit.cc +++ b/gcc/tree-ssa-uninit.cc @@ -988,10 +988,43 @@ warn_uninitialized_vars (bool wmaybe_uninit) wlimits wlims = { }; wlims.wmaybe_uninit = wmaybe_uninit; - gimple_stmt_iterator gsi; - basic_block bb; + auto_bb_flag ft_reachable (cfun); + + /* Mark blocks that are always executed when we ignore provably + not executed edges. */ + basic_block bb = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); + while (!(bb->flags & ft_reachable)) + { + bb->flags |= ft_reachable; + /* Find a single executable edge. */ + edge_iterator ei; + edge e, ee = NULL; + FOR_EACH_EDGE (e, ei, bb->succs) + if (e->flags & EDGE_EXECUTABLE) + { + if (!ee) + ee = e; + else + { + ee = NULL; + break; + } + } + if (ee) + bb = ee->dest; + else + { + bb = get_immediate_dominator (CDI_POST_DOMINATORS, bb); + if (!bb || bb->index == EXIT_BLOCK) + break; + } + } + FOR_EACH_BB_FN (bb, cfun) { + wlims.always_executed = (bb->flags & ft_reachable); + bb->flags &= ~ft_reachable; + edge_iterator ei; edge e; FOR_EACH_EDGE (e, ei, bb->preds) @@ -1002,14 +1035,10 @@ warn_uninitialized_vars (bool wmaybe_uninit) if (!e) continue; - basic_block succ = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); - /* ??? This could be improved when we use a greedy walk and have - some edges marked as not executable. */ - wlims.always_executed = dominated_by_p (CDI_POST_DOMINATORS, succ, bb); - if (wlims.always_executed) warn_uninit_phi_uses (bb); + gimple_stmt_iterator gsi; for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple *stmt = gsi_stmt (gsi); @@ -1030,7 +1059,7 @@ warn_uninitialized_vars (bool wmaybe_uninit) FOR_EACH_SSA_USE_OPERAND (use_p, stmt, op_iter, SSA_OP_USE) { /* BIT_INSERT_EXPR first operand should not be considered - a use for the purpose of uninit warnings. */ + a use for the purpose of uninit warnings. */ if (gassign *ass = dyn_cast (stmt)) { if (gimple_assign_rhs_code (ass) == BIT_INSERT_EXPR @@ -1041,7 +1070,7 @@ warn_uninitialized_vars (bool wmaybe_uninit) if (wlims.always_executed) warn_uninit (OPT_Wuninitialized, use, SSA_NAME_VAR (use), stmt); - else if (wmaybe_uninit) + else if (wlims.wmaybe_uninit) warn_uninit (OPT_Wmaybe_uninitialized, use, SSA_NAME_VAR (use), stmt); }