From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-x334.google.com (mail-wm1-x334.google.com [IPv6:2a00:1450:4864:20::334]) by sourceware.org (Postfix) with ESMTPS id C5CF23872200 for ; Tue, 13 Dec 2022 08:41:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org C5CF23872200 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=adacore.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=adacore.com Received: by mail-wm1-x334.google.com with SMTP id 206-20020a1c02d7000000b003d1e906ca23so1276060wmc.3 for ; Tue, 13 Dec 2022 00:41:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=adacore.com; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=R0BvgKj5RN3kM9MqMugFAWAKg3fdwSRwluS31L+BFZg=; b=WbQEE/rYdtEOuz3vqAyGsXvijaV/V+DwfbTzVLc1T5efESIWkeCoEojwgZo9vHlrh0 h34GCrLK9OfExypJjSyhd2/2sd3aWEPS46oDbPKytc/6A6QhWDsvwD4S3KzGwU7XQUdp ya7MB2m+TR+8R61QhKyOwM25l43XvwzL/mf6bqnpAwQn80GXpT8YLHnGnFAjPpf2hhzl ls1gn79qtnbYRLjJCCPMZ8sDQyy6HZxpbQicZLx7O4dljR8goHZxpIJm8+NWJZmeABhX yR6Zlqcz6absubADPZbwq9cyOvbaRZ5jxUwAHZ3ODyVv18gzv2El1OEosPJd+fbyaSxj lADQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=R0BvgKj5RN3kM9MqMugFAWAKg3fdwSRwluS31L+BFZg=; b=PZPlVZMjbgLyl0epB2iTWK9hGxnba9TwZUhaX4BKYuSIEOUpOJaP6eqa8JnkVo0VI9 iPBHNusRecPm4xmK98wBlMeQta3/4DIHma5vdfcTcgiL/L7jkOMYeeIIhWic6dTKN2d6 7FFkLFkCEzO+NKLpmaEYg5OFIFpvmnx1+D0G7b/hYAkjCuyUcmGOj0uNUamlGHunerCt UT5nw9rvQ+YvhUhV8PfpKk4IwmG124CSmZa93eB/FVwXRoDJ9ZDfwf4xgkhsq7oMGNNK xv4XeRosthzcf+gdL0oV8lo9U6cQ0f6vzoEjmoLBhExNuPkC5LEyND+2jl7NuEa2uNh2 Ks2Q== X-Gm-Message-State: ANoB5pnIpp4QMNdZ8kDyXqvdDDAki1t34ULLPFXCr7mKDaTJekM0H/sV tXGn4Fh4jPyMZ7gNJynseDXVQQ== X-Google-Smtp-Source: AA0mqf5XQ9jLoSeNHygzQW1KRvxtxNdJ1f71R/ijszs23We2jSB/ctSfCz4jApNiWj5x5vF91DBFpg== X-Received: by 2002:a7b:c301:0:b0:3cf:82b9:2fe6 with SMTP id k1-20020a7bc301000000b003cf82b92fe6mr18433577wmj.8.1670920894601; Tue, 13 Dec 2022 00:41:34 -0800 (PST) Received: from fomalhaut.localnet ([2a01:e0a:8d5:d990:e654:e8ff:fe8f:2ce6]) by smtp.gmail.com with ESMTPSA id d4-20020adfe2c4000000b00236488f62d6sm11087427wrj.79.2022.12.13.00.41.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Dec 2022 00:41:33 -0800 (PST) From: Eric Botcazou X-Google-Original-From: Eric Botcazou To: Claudiu Zissulescu Ianculescu Cc: gcc@gcc.gnu.org Subject: Re: Possible regression in DF analysis Date: Tue, 13 Dec 2022 09:41:32 +0100 Message-ID: <4447258.LvFx2qVVIh@fomalhaut> In-Reply-To: References: <2858689.e9J7NaK4W3@fomalhaut> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Status: No, score=-4.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,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: > 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