From patchwork Fri Mar 31 01:44:37 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: 9655369 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 0F3ED60113 for ; Fri, 31 Mar 2017 01:46:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F321428688 for ; Fri, 31 Mar 2017 01:46:34 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E638628617; Fri, 31 Mar 2017 01:46:34 +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 6CFF428617 for ; Fri, 31 Mar 2017 01:46:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934857AbdCaBqe (ORCPT ); Thu, 30 Mar 2017 21:46:34 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:34165 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934785AbdCaBqc (ORCPT ); Thu, 30 Mar 2017 21:46:32 -0400 Received: by mail-wr0-f196.google.com with SMTP id w43so16582640wrb.1 for ; Thu, 30 Mar 2017 18:46:31 -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=Ce12JZMYGAiFzmhnEeET/Gc3Zw92CPzyXoNQZKCuckU=; b=JWHMazZnwXvbUgQ5H7gnOD9ftqq7nWY3hlr5FywlfDA6yIPXcLDRMou5QYPv4sIfLv FtFdzqPYUUWdV+VwrDFi6L7SEU/co7NpUUjRwYY2WeTNMX5jnI67cCaIijvTYMDkZTrO DSEXPyaOw8oZHTRgf0Y+NnNQc+aVFGXkmFRfghYtFxZBIUf/t9ROH00A3Dluy+Q+wF+v 48LbOjRHroxiTOR5VE7j/fMLI09jtmvEzXHh5LtMiW2pFB9NpFlWCpS8E/ECkTyYl7BG PfU1LPpAK+Xg2xqJA0YV2WMAWaVItWZ4xecNLA/MqyOi+NbglxCRskPAwX98scKjyXd8 SGgg== 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=Ce12JZMYGAiFzmhnEeET/Gc3Zw92CPzyXoNQZKCuckU=; b=Sv6VjPG27aI4maspVAc8meGw7FUF3RfWZ+tx31hNi8HZiSIWZNgl4AQVAmbObahULP pmnx/kHgvYc8Pgj6XymqLKCnXAJLVMYFknEQw12wa8jkuaN+ictkoDJGTjOfFQ7BSPyp iSExY5psvgZW53PgaqmVubGSRYO1AYZUdJvic6EjgtWXXx8j0c2YSe33bunzw9bYBz7w VTVBhkXreaPKJLt8bz0SGdmR3hn8haguLm3nlwxozYjgoFDOPyhauS13H+KFG32KiOmH K/k8W6IFY2rK3kxbp55dEvemMftOR0fuaSDxgXiyz1UOXnBJutosS3dG11QyG6pZ8Ofh l8Ag== X-Gm-Message-State: AFeK/H0ud+1kRRRJ+feI8oxNe30wVFThEMDIB8IKSeOA0gXgMm9e3cUSlwGPUAgLRVvllg== X-Received: by 10.28.132.20 with SMTP id g20mr410064wmd.68.1490924790510; Thu, 30 Mar 2017 18:46:30 -0700 (PDT) Received: from localhost.localdomain ([2a02:a03f:88d:1900:cdad:92b8:5279:ae19]) by smtp.gmail.com with ESMTPSA id 189sm917023wmm.31.2017.03.30.18.46.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Mar 2017 18:46:29 -0700 (PDT) From: Luc Van Oostenryck To: linux-sparse@vger.kernel.org Cc: Christopher Li , Nicolai Stange , Luc Van Oostenryck Subject: [PATCH v4 03/25] constexpr: examine constness of casts at evaluation only Date: Fri, 31 Mar 2017 03:44:37 +0200 Message-Id: <20170331014459.9351-4-luc.vanoostenryck@gmail.com> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170331014459.9351-1-luc.vanoostenryck@gmail.com> References: <20170331014459.9351-1-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 From: Nicolai Stange Move the whole calculation of cast expressions' constness flags to the evaluation phase such that expressions like (int)__builtin_choose_expr(0, 0, 0) can now be recognized as qualifying as integer constant expressions. Signed-off-by: Nicolai Stange Signed-off-by: Luc Van Oostenryck --- evaluate.c | 37 +++++++++++++++++++++++++++++-------- expression.c | 19 ------------------- expression.h | 7 +++++++ validation/constexpr-cast.c | 25 +++++++++++++++++++++++++ 4 files changed, 61 insertions(+), 27 deletions(-) create mode 100644 validation/constexpr-cast.c diff --git a/evaluate.c b/evaluate.c index 18f1da8b3..5725e898f 100644 --- a/evaluate.c +++ b/evaluate.c @@ -271,6 +271,7 @@ warn_for_different_enum_types (struct position pos, } } +static int cast_flags(struct expression *expr, struct expression *target); static struct symbol *cast_to_bool(struct expression *expr); /* @@ -323,10 +324,10 @@ static struct expression * cast_to(struct expression *old, struct symbol *type) } expr = alloc_expression(old->pos, EXPR_IMPLIED_CAST); - expr->flags = old->flags; expr->ctype = type; expr->cast_type = type; expr->cast_expression = old; + expr->flags = cast_flags(expr, old); if (is_bool_type(type)) cast_to_bool(expr); @@ -2720,6 +2721,32 @@ static struct symbol *cast_to_bool(struct expression *expr) return expr->ctype; } +static int cast_flags(struct expression *expr, struct expression *old) +{ + struct symbol *t; + int class; + int flags = CEF_NONE; + + class = classify_type(expr->ctype, &t); + if (class & TYPE_NUM) { + flags = old->flags & ~CEF_CONST_MASK; + /* + * Cast to float type -> not an integer constant + * expression [6.6(6)]. + */ + if (class & TYPE_FLOAT) + flags &= ~CEF_CLR_ICE; + /* + * Casts of float literals to integer type results in + * a constant integer expression [6.6(6)]. + */ + else if (old->flags & CEF_FLOAT) + flags = CEF_SET_ICE; + } + + return flags; +} + static struct symbol *evaluate_cast(struct expression *expr) { struct expression *target = expr->cast_expression; @@ -2768,13 +2795,7 @@ static struct symbol *evaluate_cast(struct expression *expr) class1 = classify_type(ctype, &t1); - /* cast to non-integer type -> not an integer constant expression */ - if (!is_int(class1)) - expr->flags = CEF_NONE; - /* if argument turns out to be not an integer constant expression *and* - it was not a floating literal to start with -> too bad */ - else if (expr->flags & CEF_ICE && !(target->flags & CEF_ICE)) - expr->flags = CEF_NONE; + expr->flags = cast_flags(expr, target); /* * You can always throw a value away by casting to diff --git a/expression.c b/expression.c index 4189e5f3a..3262cf22c 100644 --- a/expression.c +++ b/expression.c @@ -722,25 +722,6 @@ static struct token *cast_expression(struct token *token, struct expression **tr if (!v) return token; cast->cast_expression = v; - - cast->flags = v->flags & ~CEF_CONST_MASK; - /* - * Up to now, we missed the (int).0 case here - * which should really get a - * CEF_ICE marker. Also, - * conversion to non-numeric types is not - * properly reflected up to this point. - * However, we do not know until evaluation. - * For the moment, in order to preserve - * semantics, speculatively set - * CEF_ICE if - * CEF_FLOAT is - * set. evaluate_cast() will unset - * inappropriate flags again after examining - * type information. - */ - if (v->flags & CEF_FLOAT) - cast->flags |= CEF_SET_ICE; return token; } } diff --git a/expression.h b/expression.h index ec94ff4a1..c084783c8 100644 --- a/expression.h +++ b/expression.h @@ -120,6 +120,13 @@ enum constexpr_flag { CEF_CONST_MASK = (CEF_INT | CEF_FLOAT | CEF_CHAR), }; +/* + * not an integer constant expression => neither of integer, + * enumeration and character constant + */ +#define CEF_CLR_ICE \ + (CEF_ICE | CEF_INT | CEF_ENUM | CEF_CHAR) + enum { Taint_comma = 1, }; /* for expr->taint */ diff --git a/validation/constexpr-cast.c b/validation/constexpr-cast.c new file mode 100644 index 000000000..27069614c --- /dev/null +++ b/validation/constexpr-cast.c @@ -0,0 +1,25 @@ +static int a[] = { + [(int)0] = 0, // OK + [(int)(int)0] = 0, // OK + [(int)0.] = 0, // OK + [(int)(int)0.] = 0, // OK + [(int)__builtin_choose_expr(0, 0, 0)] = 0, // OK + [(int)__builtin_choose_expr(0, 0, 0.)] = 0, // OK + + [(int)(float)0] = 0, // KO + [(int)(float)0.] = 0, // KO + + [(int)(void*)0] = 0, // KO + [(int)(void*)0.] = 0, // KO + +}; +/* + * check-name: Expression constness propagation in casts + * + * check-error-start +constexpr-cast.c:9:11: error: bad integer constant expression +constexpr-cast.c:10:11: error: bad integer constant expression +constexpr-cast.c:12:11: error: bad integer constant expression +constexpr-cast.c:13:11: error: bad integer constant expression + * check-error-end + */