From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 106275 invoked by alias); 13 Apr 2017 02:28:02 -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 104744 invoked by uid 89); 13 Apr 2017 02:27:59 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=sk:delete 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; Thu, 13 Apr 2017 02:27:58 +0000 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 57D868046A for ; Thu, 13 Apr 2017 02:27:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 57D868046A Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=palves@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 57D868046A Received: from cascais.lan (ovpn04.gateway.prod.ext.phx2.redhat.com [10.5.9.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id D913417175 for ; Thu, 13 Apr 2017 02:27:57 +0000 (UTC) From: Pedro Alves To: gdb-patches@sourceware.org Subject: [PATCH 2/5] Don't memcpy non-trivially-copyable types: Make enum_flags triv. copyable Date: Thu, 13 Apr 2017 02:28:00 -0000 Message-Id: <1492050475-9238-3-git-send-email-palves@redhat.com> In-Reply-To: <1492050475-9238-1-git-send-email-palves@redhat.com> References: <1492050475-9238-1-git-send-email-palves@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-SW-Source: 2017-04/txt/msg00379.txt.bz2 The delete-memcpy-with-non-trivial-types patch exposed many instances of this problem: src/gdb/btrace.h: In function ‘btrace_insn_s* VEC_btrace_insn_s_quick_insert(VEC_btrace_insn_s*, unsigned int, const btrace_insn_s*, const char*, unsigned int)’: src/gdb/common/vec.h:948:62: error: use of deleted function ‘void* memmove(T*, const U*, size_t) [with T = btrace_insn; U = btrace_insn; = void; size_t = long unsigned int]’ memmove (slot_ + 1, slot_, (vec_->num++ - ix_) * sizeof (T)); \ ^ src/gdb/common/vec.h:436:1: note: in expansion of macro ‘DEF_VEC_FUNC_O’ DEF_VEC_FUNC_O(T) \ ^ src/gdb/btrace.h:84:1: note: in expansion of macro ‘DEF_VEC_O’ DEF_VEC_O (btrace_insn_s); ^ [...] src/gdb/common/vec.h:1060:31: error: use of deleted function ‘void* memcpy(T*, const U*, size_t) [with T = btrace_insn; U = btrace_insn; = void; size_t = long unsigned int]’ sizeof (T) * vec2_->num); \ ^ src/gdb/common/vec.h:437:1: note: in expansion of macro ‘DEF_VEC_ALLOC_FUNC_O’ DEF_VEC_ALLOC_FUNC_O(T) \ ^ src/gdb/btrace.h:84:1: note: in expansion of macro ‘DEF_VEC_O’ DEF_VEC_O (btrace_insn_s); ^ So, VECs (given it's C roots) rely on memcpy/memcpy of VEC elements to be well defined, in order to grow/reallocate its internal elements array. This means that we can only put trivially copyable types in VECs. E.g., if a type requires using a custom copy/move ctor to relocate, then we can't put it in a VEC (so we use std::vector instead). But, as shown above, we're violating that requirement. btrace_insn is currently not trivially copyable, because it contains an enum_flags field, and that is itself not trivially copyable. This patch corrects that. Note that std::vector relies on std::is_trivially_copyable too to know whether it can reallocate its elements with memcpy/memmove instead of having to call copy/move ctors and dtors, so if we have types in std::vectors that weren't trivially copyable because of enum_flags, this will make such vectors more efficient. gdb/ChangeLog: yyyy-mm-dd Pedro Alves * common/enum-flags.h (enum_flags): Define copy/move ctors/op= as defaulted. --- gdb/common/enum-flags.h | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/gdb/common/enum-flags.h b/gdb/common/enum-flags.h index e63c8a4..bea0ad5 100644 --- a/gdb/common/enum-flags.h +++ b/gdb/common/enum-flags.h @@ -120,15 +120,12 @@ public: : m_enum_value ((enum_type) 0) {} - enum_flags (const enum_flags &other) - : m_enum_value (other.m_enum_value) - {} - - enum_flags &operator= (const enum_flags &other) - { - m_enum_value = other.m_enum_value; - return *this; - } + /* Define copy/move ctor/op= as defaulted so that enum_flags is + trivially copyable. */ + enum_flags (const enum_flags &other) = default; + enum_flags (enum_flags &&) noexcept = default; + enum_flags &operator= (const enum_flags &other) = default; + enum_flags &operator= (enum_flags &&) = default; /* If you get an error saying these two overloads are ambiguous, then you tried to mix values of different enum types. */ -- 2.5.5