From patchwork Thu Nov 21 01:49:26 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Johansson X-Patchwork-Id: 13881556 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C54CBD743FC for ; Thu, 21 Nov 2024 01:50:24 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tDwHx-0001fT-P9; Wed, 20 Nov 2024 20:47:21 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tDwHu-0001dO-MO for qemu-devel@nongnu.org; Wed, 20 Nov 2024 20:47:18 -0500 Received: from rev.ng ([94.130.142.21]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tDwHt-0004ZP-7S for qemu-devel@nongnu.org; Wed, 20 Nov 2024 20:47:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=rev.ng; s=dkim; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive:List-Unsubscribe:List-Unsubscribe-Post: List-Help; bh=gOqbb409IemoDA9cXRKMqCB6ZUSy0Qk58RmK/jyokAM=; b=LQ28/UUF0fF3/ns UMioWfeToFvaoy2MSNVq5FSH6NXASrhNUrNy3f2kiAOfLXOB6pTSB0kroWBFiG9knggN1/iuBQwQ2 S2EGXvo+uYlj6Rac5jrZj9VWFRavn1To83P/d9SFeBmLmeQsZsDwhRL87lWnVDifCI1ygWJ7oXeWj dI=; To: qemu-devel@nongnu.org Cc: ale@rev.ng, ltaylorsimpson@gmail.com, bcain@quicinc.com, richard.henderson@linaro.org, philmd@linaro.org, alex.bennee@linaro.org Subject: [RFC PATCH v1 22/43] helper-to-tcg: PrepareForTcgPass, remove functions w. cycles Date: Thu, 21 Nov 2024 02:49:26 +0100 Message-ID: <20241121014947.18666-23-anjo@rev.ng> In-Reply-To: <20241121014947.18666-1-anjo@rev.ng> References: <20241121014947.18666-1-anjo@rev.ng> MIME-Version: 1.0 Received-SPF: pass client-ip=94.130.142.21; envelope-from=anjo@rev.ng; helo=rev.ng X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-to: Anton Johansson X-Patchwork-Original-From: Anton Johansson via From: Anton Johansson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Functions with cycles are removed for two primary reasons: * as a simplifying assumption for register allocation which occurs down the line, and; * if a function contains cycles post-optimization neither unrolling or loop vectorization were beneficial, and the function _might_ be better suited as a helper anyway. Cycles are detected by iterating over Strongly Connected Components (SCCs) which imply the existence of cycles if: - a SCC contains more than one node, or; - it has a self-edge. Signed-off-by: Anton Johansson --- .../PrepareForTcgPass/PrepareForTcgPass.cpp | 32 +++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/subprojects/helper-to-tcg/passes/PrepareForTcgPass/PrepareForTcgPass.cpp b/subprojects/helper-to-tcg/passes/PrepareForTcgPass/PrepareForTcgPass.cpp index f0ef1abd17..ccbe3820a0 100644 --- a/subprojects/helper-to-tcg/passes/PrepareForTcgPass/PrepareForTcgPass.cpp +++ b/subprojects/helper-to-tcg/passes/PrepareForTcgPass/PrepareForTcgPass.cpp @@ -16,10 +16,42 @@ // #include +#include +#include +#include using namespace llvm; +static void removeFunctionsWithLoops(Module &M, ModuleAnalysisManager &MAM) +{ + // Iterate over all Strongly Connected Components (SCCs), a SCC implies + // the existence of loops if: + // - it has more than one node, or; + // - it has a self-edge. + SmallVector FunctionsToRemove; + for (Function &F : M) { + if (F.isDeclaration()) { + continue; + } + for (auto It = scc_begin(&F); !It.isAtEnd(); ++It) { +#if LLVM_VERSION_MAJOR > 10 + if (It.hasCycle()) { +#else + if (It.hasLoop()) { +#endif + FunctionsToRemove.push_back(&F); + break; + } + } + } + + for (auto *F : FunctionsToRemove) { + F->deleteBody(); + } +} + PreservedAnalyses PrepareForTcgPass::run(Module &M, ModuleAnalysisManager &MAM) { + removeFunctionsWithLoops(M, MAM); return PreservedAnalyses::none(); }