From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E74BC433DF for ; Mon, 3 Aug 2020 14:29:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2AB57206D4 for ; Mon, 3 Aug 2020 14:29:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HlZ2CySh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726515AbgHCO3I (ORCPT ); Mon, 3 Aug 2020 10:29:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726358AbgHCO3I (ORCPT ); Mon, 3 Aug 2020 10:29:08 -0400 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83A0DC06174A for ; Mon, 3 Aug 2020 07:29:08 -0700 (PDT) Received: by mail-pj1-x1031.google.com with SMTP id e4so7731591pjd.0 for ; Mon, 03 Aug 2020 07:29:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:subject:message-id:mime-version:content-disposition; bh=MqJh2LnViJ30CZNBJLko/MDIyLNqKueaQXfb3Y1bwTc=; b=HlZ2CyShgD9xEM/+wFv0NmN0oJG9gYgc9ugvwwWzqGByJ7zctYkxMSgr+BvRojfrK1 KokCewrtW1OpW7dzWaVnEcAicfaBXGLHQuPXCKTyy2aTsfgCP6U4cjcv9tuG07AwTObE u7/2sE/sbbgmYwc9v4OSYUqSVHl78q73eEQYAppXXaWtonvwMgHmbopc3jESLary1ltT o5/Wm1o43qMEv1eFG+n5c5fT11iLdtsLGoXj+4zva+nrGb4QDlxFvDZSKQ4BDMtoRKcW S1MywhWW0PEB/AMxLA54RQcYYE65A4ecDbMDFj9ogIbPkC7gQHbXqBGxYe3I8awpEZmk ygxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:mime-version :content-disposition; bh=MqJh2LnViJ30CZNBJLko/MDIyLNqKueaQXfb3Y1bwTc=; b=IlYDZP+smMpiNMWIKtQ4lzft6XA2pAN0BOtcNankr5KwA5cCUvxpYc/UNNX6kc/akQ 6rbsSReqy3gGfG4tPsm/hTJlCHmYbtKUzDUGnIyVKI5ckVj/bPDcUJIYgokvR7OEoFud bXXigUOvXXVhR6ahQy6zQWxOBbCYCk7PXA6gtzjtJgxyGVJH562KdwieIY0tBpt2XMwN b1rpuUSDlHhag9Z5LE+XazK7tWmMjyFcm12184hNVvF6C03rQ5idN5qfEBnDniABir43 KV1sd2TiwPTR8Z3R6CtOOkoyGjFWrH5VRsLagLhSKHQv7NJvursFwIAU3Vp95CX74rwj nIVg== X-Gm-Message-State: AOAM530rbdJnLvSeBGzirehTGMYKbj9x0TfKL5Szlva0GBIFy470lty1 1ir1Pv8o81gYiM0QhFM3dSPFNedq X-Google-Smtp-Source: ABdhPJyL9aZeiuzWAuxVzqGipU6/EELX04wEmdWJTMogK1OorvpV33/u1Aq0UaqN+/yRTkFrtPcxgw== X-Received: by 2002:a17:90b:885:: with SMTP id bj5mr16363569pjb.133.1596464947451; Mon, 03 Aug 2020 07:29:07 -0700 (PDT) Received: from localhost (g223.115-65-55.ppp.wakwak.ne.jp. [115.65.55.223]) by smtp.gmail.com with ESMTPSA id n25sm20044365pff.51.2020.08.03.07.29.05 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Aug 2020 07:29:06 -0700 (PDT) Date: Mon, 3 Aug 2020 23:29:03 +0900 From: Stafford Horne To: linux-sparse@vger.kernel.org Subject: Issue with inline functions and switch statements Message-ID: <20200803142903.GK80756@lianli.shorne-pla.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-sparse-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sparse@vger.kernel.org Hello, I am the maintainer of the OpenRISC architecture linux port, and recently have started to look at the kbuild sparse errors. The Linux kernel kbuild process is reporting sparse error: net/dccp/proto.c: note: in included file (through include/asm-generic/atomic.h, arch/openrisc/include/asm/atomic.h, include/linux/atomic.h, ...): arch/openrisc/include/asm/cmpxchg.h:101:29: sparse: sparse: shift too big (32) for type int Example: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2256733.html I have traced this down to the case like the below. It reports an unexpected warning: simple_test.c:7:18: warning: shift too big (32) for type int This is not pssible because size = 4 should never call shift_small. I have debugged sparse when this is running and it seems that when checking the switch cases it evaluates all cases, and thinks size = 4 is possible. I am not sure if this is a problem with the sparse front end of the check logic. Can you help? -Stafford -- /* From: https://github.com/stffrdhrn/junk/tree/master/sparse-shift * Run with : sparse -O2 --arch=openrisc -m32 simple_test.c */ #include typedef unsigned long int u32; static inline u32 shift_small(int size) { return 1 << (size * 8); } static inline u32 test(int size) { printf ("Test size=%d: ", size); switch (size) { case 1: case 2: return shift_small(size); case 4: printf ("not small\n"); return 99; default: return 9999; } } int main(int argc, char ** argv) { test(1); test(2); test(4); // simple_test.c:7:18: warning: shift too big (32) for type int return 0; }