From patchwork Fri Jan 26 10:05:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Federico Serafini X-Patchwork-Id: 13532370 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.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 24C20C4828A for ; Fri, 26 Jan 2024 10:08:58 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.671913.1045450 (Exim 4.92) (envelope-from ) id 1rTJ8h-00086S-Td; Fri, 26 Jan 2024 10:08:47 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 671913.1045450; Fri, 26 Jan 2024 10:08:47 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rTJ8h-00086L-Qm; Fri, 26 Jan 2024 10:08:47 +0000 Received: by outflank-mailman (input) for mailman id 671913; Fri, 26 Jan 2024 10:08:46 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rTJ8g-0007rs-Ah for xen-devel@lists.xenproject.org; Fri, 26 Jan 2024 10:08:46 +0000 Received: from support.bugseng.com (mail.bugseng.com [162.55.131.47]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id e32ebed6-bc32-11ee-98f5-efadbce2ee36; Fri, 26 Jan 2024 11:08:44 +0100 (CET) Received: from Dell.homenet.telecomitalia.it (host-87-16-84-78.retail.telecomitalia.it [87.16.84.78]) by support.bugseng.com (Postfix) with ESMTPSA id 888294EE0749; Fri, 26 Jan 2024 11:08:43 +0100 (CET) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: e32ebed6-bc32-11ee-98f5-efadbce2ee36 From: Federico Serafini To: xen-devel@lists.xenproject.org Cc: consulting@bugseng.com, Federico Serafini , Andrew Cooper , George Dunlap , Jan Beulich , Julien Grall , Stefano Stabellini , Wei Liu Subject: [XEN PATCH v2 1/3] xen: introduce STATIC_ASSERT_UNREACHABLE() Date: Fri, 26 Jan 2024 11:05:41 +0100 Message-Id: <42fc6ae8d3eb802429d29c774502ff232340dc84.1706259490.git.federico.serafini@bugseng.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Introduce macro STATIC_ASSERT_UNREACHABLE() to check that a program point is considered unreachable by the static analysis performed by the compiler. The use of such macro will lead to one of the following outcomes: - the program point identified by the macro is considered unreachable, then the compiler removes the macro; - the program point identified by the macro is not considered unreachable, then the compiler does not remove the macro, which will lead to a failure in the build process caused by an assembler error. Signed-off-by: Federico Serafini Acked-by: Jan Beulich --- Changes in v2: - removed constraint about optimization level -O0; - use capital letters for macro name; - add missing blanks; - remove stray semicolon; - cite the assertion failure in the error message. --- xen/include/xen/compiler.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h index 16d554f2a5..062f54449c 100644 --- a/xen/include/xen/compiler.h +++ b/xen/include/xen/compiler.h @@ -64,6 +64,13 @@ # define fallthrough do {} while (0) /* fallthrough */ #endif +/* + * Add the following macro to check that a program point is considered + * unreachable by the static analysis performed by the compiler. + */ +#define STATIC_ASSERT_UNREACHABLE() \ + asm ( ".error \"static assertion failed: unreachable\"" ) + #ifdef __clang__ /* Clang can replace some vars with new automatic ones that go in .data; * mark all explicit-segment vars 'used' to prevent that. */