From patchwork Thu Nov 21 01:49:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Johansson X-Patchwork-Id: 13881571 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 C1E65D743FD for ; Thu, 21 Nov 2024 01:52:21 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tDwHt-0001cx-LX; Wed, 20 Nov 2024 20:47:17 -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 1tDwHr-0001bW-Nb for qemu-devel@nongnu.org; Wed, 20 Nov 2024 20:47:15 -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 1tDwHq-0004Xz-4e for qemu-devel@nongnu.org; Wed, 20 Nov 2024 20:47:15 -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=NewhKMIelYRuDNznnvD5yTlXbeDt4XshQYjlz/pQPQs=; b=hKczrorhim53phv kA62HkSwy+a2H7Y7YBBwMRmuAn2jCl4sxhMrrTtMHVT3OCqMJoYbvv44OY9xkEtjafP1P94/5i7Eq Wx6dKEw8kGEVwheFDZm38N1KiZhyNpR3CkSIo5NYDZ/WPApzDdNcwPqIBMmAkxlIxoj7g7tRi+JSV IM=; 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 17/43] helper-to-tcg: PrepareForOptPass, undef llvm.returnaddress Date: Thu, 21 Nov 2024 02:49:21 +0100 Message-ID: <20241121014947.18666-18-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 Convert llvm.returnaddress arguments to cpu_[ld|st]*() to undef, causing the LLVM optmizer to discard the intrinsics. Needed as llvm.returnadress is not representable in TCG, and usually results from usage of GETPC() in helper functions. Signed-off-by: Anton Johansson --- .../PrepareForOptPass/PrepareForOptPass.cpp | 48 +++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/subprojects/helper-to-tcg/passes/PrepareForOptPass/PrepareForOptPass.cpp b/subprojects/helper-to-tcg/passes/PrepareForOptPass/PrepareForOptPass.cpp index 22509008c8..b357debb5d 100644 --- a/subprojects/helper-to-tcg/passes/PrepareForOptPass/PrepareForOptPass.cpp +++ b/subprojects/helper-to-tcg/passes/PrepareForOptPass/PrepareForOptPass.cpp @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -197,9 +198,56 @@ static void cullUnusedFunctions(Module &M, AnnotationMapTy &Annotations, } } +struct RetAddrReplaceInfo { + User *Parent; + unsigned OpIndex; + Type *Ty; +}; + +static void replaceRetaddrWithUndef(Module &M) +{ + // Replace uses of llvm.returnaddress arguments to cpu_ld* w. undef, + // and let optimizations remove it. Needed as llvm.returnaddress is + // not reprensentable in TCG. + SmallVector UsesToReplace; + Function *Retaddr = Intrinsic::getDeclaration(&M, Intrinsic::returnaddress); + // Loop over all calls to llvm.returnaddress + for (auto *CallUser : Retaddr->users()) { + auto *Call = dyn_cast(CallUser); + if (!Call) { + continue; + } + for (auto *PtrToIntUser : Call->users()) { + auto *Cast = dyn_cast(PtrToIntUser); + if (!Cast) { + continue; + } + for (Use &U : Cast->uses()) { + auto *Call = dyn_cast(U.getUser()); + Function *F = Call->getCalledFunction(); + StringRef Name = F->getName(); + if (Name.startswith("cpu_ld") or Name.startswith("cpu_st")) { + UsesToReplace.push_back({ + .Parent = U.getUser(), + .OpIndex = U.getOperandNo(), + .Ty = U->getType(), + }); + } + } + } + } + + // Defer replacement to not invalidate iterators + for (RetAddrReplaceInfo &RI : UsesToReplace) { + auto *Undef = UndefValue::get(RI.Ty); + RI.Parent->setOperand(RI.OpIndex, Undef); + } +} + PreservedAnalyses PrepareForOptPass::run(Module &M, ModuleAnalysisManager &MAM) { collectAnnotations(M, ResultAnnotations); cullUnusedFunctions(M, ResultAnnotations, TranslateAllHelpers); + replaceRetaddrWithUndef(M); return PreservedAnalyses::none(); }