From patchwork Tue Jan 25 23:33:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Polacek X-Patchwork-Id: 50445 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 9F3F7385ED4A for ; Tue, 25 Jan 2022 23:34:22 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9F3F7385ED4A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1643153662; bh=CybYuZIsd50+wiV79cFOkKa8BR4kFuNV1ci4ChPogCM=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:Cc:From; b=vXIE5kxjmBJcfklq41BGnkxTEjEZL2xmudPVPgm5ZmB9UDK7hM+PbyKHGqHKTPGA4 GlGMzSA6zpguA3iISuHhHeCzn3gZR/vh5BbVHyS/ZPCm0edmNzBLPTidxvRUr8HZn4 dX+IdwwBAcAh7eErKLM7cGUpPZLH+nZK/rS/VUA8= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id ED269385380A for ; Tue, 25 Jan 2022 23:33:52 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org ED269385380A Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-14-KZ64Jn4dN1ON17jeWlC31w-1; Tue, 25 Jan 2022 18:33:50 -0500 X-MC-Unique: KZ64Jn4dN1ON17jeWlC31w-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 386182F26 for ; Tue, 25 Jan 2022 23:33:49 +0000 (UTC) Received: from pdp-11.hsd1.ma.comcast.net (unknown [10.22.10.195]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1EC1C78C2A; Tue, 25 Jan 2022 23:33:41 +0000 (UTC) To: GCC Patches Subject: [PATCH] warn-access: Prevent -Wuse-after-free on ARM [PR104213] Date: Tue, 25 Jan 2022 18:33:33 -0500 Message-Id: <20220125233333.695137-1-polacek@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Marek Polacek via Gcc-patches From: Marek Polacek Reply-To: Marek Polacek Cc: Martin Sebor Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" Here, -Wuse-after-free warns about using 'this' which, on ARM, cdtors return, as mandated by the EABI. To be entirely correct, it only requires it for C1 and C2 ctors and D2 and D1 dtors, but I don't feel like changing that now and possibly running into issues later on. This patch uses suppress_warning on 'this' for certain cdtor_returns_this cases in the C++ FE, and then warn_invalid_pointer makes use of this information and doesn't warn. In my first attempt I tried suppress_warning the MODIFY_EXPR or RETURN_EXPR we build in build_delete_destructor_body, but the complication is that the suppress_warning bits don't always survive gimplification; see e.g. gimplify_modify_expr where we do 6130 if (COMPARISON_CLASS_P (*from_p)) 6131 copy_warning (assign, *from_p); but here we're not dealing with a comparison. Removing that check regresses uninit-pr74762.C. Adding copy_warning (assign, *expr_p) regresses c-c++-common/uninit-17.c. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? PR target/104213 gcc/cp/ChangeLog: * decl.cc (finish_constructor_body): Suppress -Wuse-after-free. (finish_destructor_body): Likewise. * optimize.cc (build_delete_destructor_body): Likewise. gcc/ChangeLog: * gimple-ssa-warn-access.cc (pass_waccess::warn_invalid_pointer): Don't warn when the SSA_NAME_VAR of REF has supressed -Wuse-after-free. gcc/testsuite/ChangeLog: * g++.dg/warn/Wuse-after-free2.C: New test. --- gcc/cp/decl.cc | 2 ++ gcc/cp/optimize.cc | 1 + gcc/gimple-ssa-warn-access.cc | 14 +++++++++++--- gcc/testsuite/g++.dg/warn/Wuse-after-free2.C | 10 ++++++++++ 4 files changed, 24 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/g++.dg/warn/Wuse-after-free2.C base-commit: aeac414923aa1e87986c7fc6f9b921d89a9b86cf diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 22d3dd1e2ad..6534a7fd320 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -17315,6 +17315,7 @@ finish_constructor_body (void) add_stmt (build_stmt (input_location, LABEL_EXPR, cdtor_label)); val = DECL_ARGUMENTS (current_function_decl); + suppress_warning (val, OPT_Wuse_after_free); val = build2 (MODIFY_EXPR, TREE_TYPE (val), DECL_RESULT (current_function_decl), val); /* Return the address of the object. */ @@ -17408,6 +17409,7 @@ finish_destructor_body (void) tree val; val = DECL_ARGUMENTS (current_function_decl); + suppress_warning (val, OPT_Wuse_after_free); val = build2 (MODIFY_EXPR, TREE_TYPE (val), DECL_RESULT (current_function_decl), val); /* Return the address of the object. */ diff --git a/gcc/cp/optimize.cc b/gcc/cp/optimize.cc index 4ad3f1dc9aa..13ab8b7361e 100644 --- a/gcc/cp/optimize.cc +++ b/gcc/cp/optimize.cc @@ -166,6 +166,7 @@ build_delete_destructor_body (tree delete_dtor, tree complete_dtor) if (targetm.cxx.cdtor_returns_this ()) { tree val = DECL_ARGUMENTS (delete_dtor); + suppress_warning (val, OPT_Wuse_after_free); val = build2 (MODIFY_EXPR, TREE_TYPE (val), DECL_RESULT (delete_dtor), val); add_stmt (build_stmt (0, RETURN_EXPR, val)); diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc index 8bc33eeb6fa..484bcd34c25 100644 --- a/gcc/gimple-ssa-warn-access.cc +++ b/gcc/gimple-ssa-warn-access.cc @@ -3880,9 +3880,17 @@ pass_waccess::warn_invalid_pointer (tree ref, gimple *use_stmt, bool maybe, bool equality /* = false */) { /* Avoid printing the unhelpful "" in the diagnostics. */ - if (ref && TREE_CODE (ref) == SSA_NAME - && (!SSA_NAME_VAR (ref) || DECL_ARTIFICIAL (SSA_NAME_VAR (ref)))) - ref = NULL_TREE; + if (ref && TREE_CODE (ref) == SSA_NAME) + { + tree var = SSA_NAME_VAR (ref); + if (!var) + ref = NULL_TREE; + /* Don't warn for cases like when a cdtor returns 'this' on ARM. */ + else if (warning_suppressed_p (var, OPT_Wuse_after_free)) + return; + else if (DECL_ARTIFICIAL (var)) + ref = NULL_TREE; + } location_t use_loc = gimple_location (use_stmt); if (use_loc == UNKNOWN_LOCATION) diff --git a/gcc/testsuite/g++.dg/warn/Wuse-after-free2.C b/gcc/testsuite/g++.dg/warn/Wuse-after-free2.C new file mode 100644 index 00000000000..6d5f2bf01b5 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wuse-after-free2.C @@ -0,0 +1,10 @@ +// PR target/104213 +// { dg-do compile } +// { dg-options "-Wuse-after-free" } + +class C +{ + virtual ~C(); +}; + +C::~C() {} // { dg-bogus "used after" }