From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17801 invoked by alias); 3 Oct 2018 17:48:56 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 17629 invoked by uid 89); 3 Oct 2018 17:48:34 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 03 Oct 2018 17:48:30 +0000 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 73CF5C05D3E6; Wed, 3 Oct 2018 17:48:18 +0000 (UTC) Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id D0DA29F77; Wed, 3 Oct 2018 17:48:17 +0000 (UTC) Subject: Re: [PATCH v2 09/10] Avoid undefined behavior in expression dumping To: Tom Tromey , gdb-patches@sourceware.org References: <20181002044420.17628-1-tom@tromey.com> <20181002044420.17628-10-tom@tromey.com> From: Pedro Alves Message-ID: Date: Wed, 03 Oct 2018 17:48:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181002044420.17628-10-tom@tromey.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-10/txt/msg00081.txt.bz2 On 10/02/2018 05:44 AM, Tom Tromey wrote: > -fsanitize=undefined pointed out undefined behavior in > dump_raw_expression like: > > runtime error: load of value 2887952, which is not a valid value for type 'exp_opcode' > > dump_raw_expression will try to print the opcode for each element of > the expression, even when it is not valid. To allow this, but have it > avoid undefined behavior, this patch sets the underlying type of enum > exp_opcode, and arranges for op_name to handle invalid opcodes more > nicely. > > Before this patch, debug-expr.exp shows: > > Dump of expression @ 0x60f000007750, before conversion to prefix form: > Language c, 8 elements, 16 bytes each. > Index Opcode Hex Value String Value > 0 OP_TYPE 89 Y............... > 107820862850704 ..:..b.......... > 2 OP_TYPE 89 Y............... > 3 OP_VAR_VALUE 40 (............... > 4 107820861806352 ..*..b.......... > 5 107820861805152 `.*..b.......... > 6 OP_VAR_VALUE 40 (............... > 7 UNOP_MEMVAL_TYPE 57 9............... > > Afterward, the output is: > > Dump of expression @ 0x4820f90, before conversion to prefix form: > Language c, 8 elements, 16 bytes each. > Index Opcode Hex Value String Value > 0 OP_TYPE 89 Y............... > 1 unknown opcode: 176 75444400 .0.............. > 2 OP_TYPE 89 Y............... > 3 OP_VAR_VALUE 40 (............... > 4 OP_BOOL 74616912 P.r............. > 5 unknown opcode: 128 74615680 ..r............. > 6 OP_VAR_VALUE 40 (............... > 7 UNOP_MEMVAL_TYPE 57 9............... > LGTM. Thanks for adding the example. Thanks, Pedro Alves