From patchwork Sat Jun 3 08:01:35 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luc Van Oostenryck X-Patchwork-Id: 9764059 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D383C602B6 for ; Sat, 3 Jun 2017 08:01:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C55BB28236 for ; Sat, 3 Jun 2017 08:01:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BA1E9285CE; Sat, 3 Jun 2017 08:01:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.3 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5082828236 for ; Sat, 3 Jun 2017 08:01:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751077AbdFCIBw (ORCPT ); Sat, 3 Jun 2017 04:01:52 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:36400 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167AbdFCIBv (ORCPT ); Sat, 3 Jun 2017 04:01:51 -0400 Received: by mail-wm0-f66.google.com with SMTP id k15so22126499wmh.3 for ; Sat, 03 Jun 2017 01:01:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=u25vZ9qfcGskrWiMfdTLB9UeWfNMrIL6GQMg1MGIJ+0=; b=DDElkZkAjU7XYufkhED07mBjJSO8+RJYup7R6wJUkza4kX3g/leqv7XgAe5GKK+8ut OfhjgGsu4dGkGkpPEnx54PeJaETUB0pXLH3FmbcSr4OhciLp7ith37kcZ0Z+++iC/8X8 ApsdsC6gLXxXGraQIG3GCXepPZ8HqAZyaROa/tKqrcf8LiN7i21iQz3jsUaWh2HXltsq IXKV2qNYQi4kij3O4hqJnrfPdalJYMXRdWb3jG9x4jUisfXoPb2og4EiSYMSu/1UMRHP PtpDbefbltK2GCz6JH8AJ3m50W8rl8rEHEfXvkeQwHO1wXmNe6aW2FkQdFgV/wcI8xqK SIhw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=u25vZ9qfcGskrWiMfdTLB9UeWfNMrIL6GQMg1MGIJ+0=; b=W69x4ewGjLZh4DlnOS0NymSSdc788sgaf1+F+Wfpn2qpO7keY06o4xiWxrZUzOJ8ND G+feEeD8SmCePi8Qwoi4yzYG6VdNRwjVBDYewoGNhz/v1o7wLQ1jxY1tk3QJQDD3Em24 OXL9Nnf8QPB3k+Gsam/sAkrI7UzuKtPj7QN4YxSiNwBA/GgGO1oRSL+IhY06gMsIB2lV Ta6sxoFxtFFVkgUbL4nnDlPFl/7Kvg2ljLYUqyeFAExCQKk05gkbIKth5pN+GfSt1rQe 7ZPAihDI0FpAhY0K4fMigdnytRAePUgFEnwy9s0mkusCgDn7u/OSV2BRiooJ6lqQ6N2w 7OCw== X-Gm-Message-State: AODbwcArO3sljU3YtabpSfTEHDrseAwmIOWX1+25hODxW58E7Iot3677 IgYL9wkoeKv1RGRVmG0= X-Received: by 10.80.162.165 with SMTP id 34mr9045964edm.151.1496476909849; Sat, 03 Jun 2017 01:01:49 -0700 (PDT) Received: from localhost.localdomain ([2a02:a03f:89c:5400:65b4:e9ec:d7a6:723a]) by smtp.gmail.com with ESMTPSA id j7sm1065641edh.36.2017.06.03.01.01.48 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 03 Jun 2017 01:01:49 -0700 (PDT) From: Luc Van Oostenryck To: linux-sparse@vger.kernel.org Cc: Chris Li , Luc Van Oostenryck Subject: [PATCH v2 8/8] div0: warn on float divide by 0 also when the lhs is not constant Date: Sat, 3 Jun 2017 10:01:35 +0200 Message-Id: <20170603080135.46477-9-luc.vanoostenryck@gmail.com> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170603080135.46477-1-luc.vanoostenryck@gmail.com> References: <20170603080135.46477-1-luc.vanoostenryck@gmail.com> Sender: linux-sparse-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sparse@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The current code detects and warns on division by zero but only when the left-hand side is a constant value. Fix that by moving up the code which detect such divisions before checking if the LHS is a constant. Signed-off-by: Luc Van Oostenryck --- expand.c | 18 ++++++++++-------- validation/div-by-zero-fp.c | 24 ++++++++++++++++++++++++ 2 files changed, 34 insertions(+), 8 deletions(-) create mode 100644 validation/div-by-zero-fp.c diff --git a/expand.c b/expand.c index 71fbf209c..6b0dbf656 100644 --- a/expand.c +++ b/expand.c @@ -325,19 +325,23 @@ static int simplify_float_binop(struct expression *expr) unsigned long mod = expr->ctype->ctype.modifiers; long double l, r, res; - if (left->type != EXPR_FVALUE || right->type != EXPR_FVALUE) + if (right->type != EXPR_FVALUE) return 0; - l = left->fvalue; r = right->fvalue; + if (!r && expr->op == '/') + goto Div; + + if (left->type != EXPR_FVALUE) + return 0; + l = left->fvalue; if (mod & MOD_LONGLONG) { switch (expr->op) { case '+': res = l + r; break; case '-': res = l - r; break; case '*': res = l * r; break; - case '/': if (!r) goto Div; - res = l / r; break; + case '/': res = l / r; break; default: return 0; } } else if (mod & MOD_LONG) { @@ -345,8 +349,7 @@ static int simplify_float_binop(struct expression *expr) case '+': res = (double) l + (double) r; break; case '-': res = (double) l - (double) r; break; case '*': res = (double) l * (double) r; break; - case '/': if (!r) goto Div; - res = (double) l / (double) r; break; + case '/': res = (double) l / (double) r; break; default: return 0; } } else { @@ -354,8 +357,7 @@ static int simplify_float_binop(struct expression *expr) case '+': res = (float)l + (float)r; break; case '-': res = (float)l - (float)r; break; case '*': res = (float)l * (float)r; break; - case '/': if (!r) goto Div; - res = (float)l / (float)r; break; + case '/': res = (float)l / (float)r; break; default: return 0; } } diff --git a/validation/div-by-zero-fp.c b/validation/div-by-zero-fp.c new file mode 100644 index 000000000..957bc732c --- /dev/null +++ b/validation/div-by-zero-fp.c @@ -0,0 +1,24 @@ +double fbad(double a) { return 2.0 / 0; } +double gbad(double a) { return 2.0 / 0.0; } +double fool(double a) { return a / 0; } +double ffoo(double a) { return a / 0.0; } + +double fbar(double a) { if (a && 0) a / 0.0; return 0; } +double fbaz(double a) { return a /= 0.0; } +double fquz(double a) { return a / (a && 0); } + +/* + * check-name: div-by-zero-fp.c + * check-command: sparse -Wno-decl $file + * check-known-to-fail + * + * check-error-start +div-by-zero-fp.c:1:36: warning: division by zero +div-by-zero-fp.c:2:36: warning: division by zero +div-by-zero-fp.c:3:34: warning: division by zero +div-by-zero-fp.c:4:34: warning: division by zero +div-by-zero-fp.c:6:39: warning: division by zero +div-by-zero-fp.c:7:34: warning: division by zero +div-by-zero-fp.c:8:34: warning: division by zero + * check-error-end + */