From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ej1-x629.google.com (mail-ej1-x629.google.com [IPv6:2a00:1450:4864:20::629]) by sourceware.org (Postfix) with ESMTPS id BE4D13874156 for ; Tue, 13 Dec 2022 12:30:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org BE4D13874156 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ej1-x629.google.com with SMTP id b2so36090219eja.7 for ; Tue, 13 Dec 2022 04:30:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=w1913VtDvst21piNJ3LbC0knm1uk4MdfU4NMchlxqeI=; b=dHFLv37+a59JfrFqDlefVY/PgmEKnQqky8yjJDwA8z/azx7KBUSQDY7A6BaA83rpV4 LhQbqR5NjEvae3j7tEmQ13TWIjsFY5dQMR9O7hrL3I+sfvlIbm7i5ewRZOhbwOACNgg5 YvdvetrWyNwgGL92bdRc772711S/5R8Ue1tds4ioNMr+ATiHJpUcBqRRIxW3DQA9yUBG bWkE4S4Ttep84dEXFqmJRYbIuMQsFnXL7W2Ye/efDIrRH2szj78s2ECaEchGWd43aQWI Bt9E/uWKt8xxpL6pC3DT37FvwyVHKE66F5Q3R5dV56GYJc4FMKyjLNUo7DI08D/Zmlvm NiSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=w1913VtDvst21piNJ3LbC0knm1uk4MdfU4NMchlxqeI=; b=omuBp43Fnc+PO+7c3PaVadCIhv30THEbjDEqhn9l6aYpiomQnban0VDPEhOQEm3tks WWHY78GSHZO2E0U911rM49i5Xd0H6rN8baZo20xV4T8Ujj/mT+utSvj98UG5Cn1rgvwW YodGS5efuDuBoLvnU3Yjo55dCAORwkHPzEwyIH/xcJSUXDC+lScfKi9MRWgjkrtOgjgq Isejrx5udRniT5oZimqvbqub0ufkhOHzK7mQwF3ovBuBNhjowpjlTzMO7NMmJSsrKrtr CndN26TZ1fqoYKMsdwZmkoWa4KR65v16MKlJwd7P/zsGJSYSD5dhUE3I1EVauEL2FA5T 5VjQ== X-Gm-Message-State: ANoB5plclVcEtlmpFjpu6+VaFMDlj7udERyjyh/L/n7cAT7dEvAGtYVD zqBqyOIqHcP7AIIk9is7IbES0Z9tXONheSE/gKM= X-Google-Smtp-Source: AA0mqf6HDbJM/h0UmO4XZvla5rpy0N+oTJEQh4qvz8YxskWybYVKQgdkiWBDmiRtXNJbniouiM/WENi7o/6fqryL1YY= X-Received: by 2002:a17:906:4cc8:b0:7c0:c4e6:eff6 with SMTP id q8-20020a1709064cc800b007c0c4e6eff6mr24807219ejt.465.1670934648377; Tue, 13 Dec 2022 04:30:48 -0800 (PST) MIME-Version: 1.0 References: <2858689.e9J7NaK4W3@fomalhaut> <4447258.LvFx2qVVIh@fomalhaut> In-Reply-To: <4447258.LvFx2qVVIh@fomalhaut> From: Claudiu Zissulescu Ianculescu Date: Tue, 13 Dec 2022 14:30:37 +0200 Message-ID: Subject: Re: Possible regression in DF analysis To: Eric Botcazou Cc: gcc@gcc.gnu.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,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 List-Id: It looks like that. The df_analyze_loop is only looking at the loop BBs, and it is not clear for me if df_analyze_loop is required to have all the df_live_outs correctly computed or not. Do you know if it is true? If the df_analyze_loop is not supposed to compute all the df_live_outs correctly, then the error resides in how loop-doloop is using the iv_analysis_loop_init(). Thank you for your help, Claudiu On Tue, Dec 13, 2022 at 10:41 AM Eric Botcazou wrote: > > > The problem shows in loop-doloop.c when I introduce a loop end pattern > > that replaces the first jump instruction (JUMP_INSN 15) with a pattern > > that clobbers CC reg. However, the DF doesn't look like it works as > > the doloop step cannot find the CC reg alive. Please see > > loop-doloop.c:766. Hence, it introduces the doloop_end patterns, and > > renders the compare instruction (INSN 14) dead code. leading to > > errors. > > So df_get_live_out does not contain the CC register? iv_analysis_loop_init > only performs a local update of the DF information, maybe it does not cover > the basic block containing insn 14 and 15? > > -- > Eric Botcazou > >