From patchwork Wed May 31 03:22:06 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: 9755729 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 6725D602CA for ; Wed, 31 May 2017 03:22:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5A1CB205F8 for ; Wed, 31 May 2017 03:22:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4EFC028474; Wed, 31 May 2017 03:22:27 +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 DA0C3205F8 for ; Wed, 31 May 2017 03:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751120AbdEaDWZ (ORCPT ); Tue, 30 May 2017 23:22:25 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:36061 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114AbdEaDWY (ORCPT ); Tue, 30 May 2017 23:22:24 -0400 Received: by mail-wm0-f65.google.com with SMTP id k15so1016715wmh.3 for ; Tue, 30 May 2017 20:22:24 -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=ocyRO4HKz2TEYSUrh0s5HrKl13u2NJzwCfq6AiOJhu8=; b=XSpXkHRXVX2ZT2K4Vef1+D4INNVqKDQx/kp/rrKUVvGXntjwboRCRGT3HPkOXJGrmR cJvt6xvWRkL0tPIeBcAJQ92cgaVmukR/Zi4ojaoxYpCTR2pQNckPuIutlOVj5kaLWjoR mD2/kJd6RxBujPX34jLy/9v6jGODhPLeZDWLD5D29yqYpm5Fq9ehLRhzmPXU2Dar7CSo HaLGmoOMhzAPc9jgvLKyYoSqbItziADrz3Ffi2iUWyywd30suFZdD4pXCqgRE/WWldnd 5hCHcKaXCXLrXWETarD5+AvkzNxhsHd0zm8w4XqrlHhvLDTUrbPWQouaYtBFdhKormKi kkMQ== 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=ocyRO4HKz2TEYSUrh0s5HrKl13u2NJzwCfq6AiOJhu8=; b=g5Z3CXXpDFdfFqcFLfy1IfqVE62TDITExxHKCZirNtJGXlgH+HCUBYEuoO0ryod5/+ eTQVQlzP7jgtSXd+ZUE3VNfUCHcPsltOW+WuETQDL+1NM9R29hnoOsApcy7cfegs9neP Q/Lf+mvkGtwGSjCV38iVmDEAXbEcckmzvfplKRJ9zFyIKF4W7EVKrGdwDd+V1Lm6cX3B H9r6rXWk/DgiCAE3AL7J9FlNZ/dVkL/vO9/8Lw6UhwUJEpm4yvci44TMxoCkxkY0xJFH MlqEagzgKWe1YWo/q4x6b09UqX+Q8Ga6Txu0vBv1YmrJVL9nMHNEurrNVQtfp9PFsOZZ iyYQ== X-Gm-Message-State: AODbwcDBA/GkGN1XKA3VCboh7gZ2KKCQmWRSeNUqpupSUbeSwuAb7jRh oIKNB9twevIvxQHxOjY= X-Received: by 10.28.30.139 with SMTP id e133mr3948073wme.71.1496200943251; Tue, 30 May 2017 20:22:23 -0700 (PDT) Received: from localhost.localdomain ([2a02:a03f:89c:5400:25d0:8511:1e85:9d96]) by smtp.gmail.com with ESMTPSA id y3sm31676991wmh.21.2017.05.30.20.22.22 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 May 2017 20:22:22 -0700 (PDT) From: Luc Van Oostenryck To: linux-sparse@vger.kernel.org Cc: Luc Van Oostenryck Subject: [PATCH 8/9] div0: warn on float divide by 0 also when the lhs is not constant Date: Wed, 31 May 2017 05:22:06 +0200 Message-Id: <20170531032207.95830-9-luc.vanoostenryck@gmail.com> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170531032207.95830-1-luc.vanoostenryck@gmail.com> References: <20170531032207.95830-1-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 | 16 ++++++++++++++++ 2 files changed, 26 insertions(+), 8 deletions(-) create mode 100644 validation/div-by-zero-fp.c diff --git a/expand.c b/expand.c index 8fd258e25..dacee7a76 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..787af1636 --- /dev/null +++ b/validation/div-by-zero-fp.c @@ -0,0 +1,16 @@ +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; } + +/* + * check-name: div-by-zero-fp.c + * check-command: sparse -Wno-decl $file + * + * 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 + * check-error-end + */