From patchwork Tue Jul 26 19:03:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Polacek X-Patchwork-Id: 56346 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 736E538582BC for ; Tue, 26 Jul 2022 19:04:41 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 736E538582BC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1658862281; bh=iWLFyG7v7I61Pqvk11UsOfBUzTjLcox0tEjav4lKNoc=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:Cc:From; b=UMGURspydD142m8emcEz9LbyGVVUDBa40r/Qg/kAxYtWRGzXAjNSiGk7B3qQPYlMx 5wOGD9sy8cdTD0PubPxb0OEqAMX7KzyNQdzypn2yn7Jp4EIbXDJkAg3DfG/te7yzak nqv1VQbOL2lDGFWUc4L+tDm7Ueez0101APcszwk4= 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 49E573858407 for ; Tue, 26 Jul 2022 19:04:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 49E573858407 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-426-0HEoZQ_1M6aSpsPErCu8Nw-1; Tue, 26 Jul 2022 15:04:09 -0400 X-MC-Unique: 0HEoZQ_1M6aSpsPErCu8Nw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6839F806015; Tue, 26 Jul 2022 19:03:50 +0000 (UTC) Received: from pdp-11.redhat.com (unknown [10.22.32.245]) by smtp.corp.redhat.com (Postfix) with ESMTP id 138861415118; Tue, 26 Jul 2022 19:03:49 +0000 (UTC) To: GCC Patches Subject: [PATCH] c-family: Honor -Wno-init-self for cv-qual vars [PR102633] Date: Tue, 26 Jul 2022 15:03:40 -0400 Message-Id: <20220726190340.432777-1-polacek@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.5 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_NONE, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) 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: Richard Biener , Joseph Myers Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" Since r11-5188-g32934a4f45a721, we drop qualifiers during l-to-r conversion by creating a NOP_EXPR. For e.g. const int i = i; that means that the DECL_INITIAL is '(int) i' and not 'i' anymore. Consequently, we don't suppress_warning here: 711 case DECL_EXPR: 715 if (VAR_P (DECL_EXPR_DECL (*expr_p)) 716 && !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p)) 717 && !TREE_STATIC (DECL_EXPR_DECL (*expr_p)) 718 && (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) == DECL_EXPR_DECL (*expr_p)) 719 && !warn_init_self) 720 suppress_warning (DECL_EXPR_DECL (*expr_p), OPT_Winit_self); because of the check on line 718 -- (int) i is not i. So -Wno-init-self doesn't disable the warning as it's supposed to. The following patch fixes it...except it doesn't, for volatile variables in C++. The problem is that for volatile int k = k; we see that the initializer has TREE_SIDE_EFFECTS, so we perform dynamic initialization. So there's no DECL_INITIAL and the suppress_warning call above is never done. I suppose we could amend get_no_uninit_warning to return true for volatile-qualified expressions. I mean, can we ever say for a fact that a volatile variable is uninitialized? Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? PR middle-end/102633 gcc/c-family/ChangeLog: * c-gimplify.cc (c_gimplify_expr): Strip NOPs of DECL_INITIAL. gcc/testsuite/ChangeLog: * c-c++-common/Winit-self1.c: New test. * c-c++-common/Winit-self2.c: New test. --- gcc/c-family/c-gimplify.cc | 18 +++++++------ gcc/testsuite/c-c++-common/Winit-self1.c | 32 ++++++++++++++++++++++++ gcc/testsuite/c-c++-common/Winit-self2.c | 31 +++++++++++++++++++++++ 3 files changed, 74 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/Winit-self1.c create mode 100644 gcc/testsuite/c-c++-common/Winit-self2.c base-commit: 600956c81c784f4a0cc9d10f6e03e01847afd961 diff --git a/gcc/c-family/c-gimplify.cc b/gcc/c-family/c-gimplify.cc index a6f26c9b0d3..2e011830846 100644 --- a/gcc/c-family/c-gimplify.cc +++ b/gcc/c-family/c-gimplify.cc @@ -712,13 +712,17 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED, /* This is handled mostly by gimplify.cc, but we have to deal with not warning about int x = x; as it is a GCC extension to turn off this warning but only if warn_init_self is zero. */ - if (VAR_P (DECL_EXPR_DECL (*expr_p)) - && !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p)) - && !TREE_STATIC (DECL_EXPR_DECL (*expr_p)) - && (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) == DECL_EXPR_DECL (*expr_p)) - && !warn_init_self) - suppress_warning (DECL_EXPR_DECL (*expr_p), OPT_Winit_self); - break; + { + tree &decl = DECL_EXPR_DECL (*expr_p); + if (VAR_P (decl) + && !DECL_EXTERNAL (decl) + && !TREE_STATIC (decl) + && (DECL_INITIAL (decl) + && tree_strip_nop_conversions (DECL_INITIAL (decl)) == decl) + && !warn_init_self) + suppress_warning (decl, OPT_Winit_self); + break; + } case PREINCREMENT_EXPR: case PREDECREMENT_EXPR: diff --git a/gcc/testsuite/c-c++-common/Winit-self1.c b/gcc/testsuite/c-c++-common/Winit-self1.c new file mode 100644 index 00000000000..2a1a755fc71 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Winit-self1.c @@ -0,0 +1,32 @@ +/* PR middle-end/102633 */ +/* { dg-do compile } */ +/* { dg-options "-Wuninitialized -Wno-init-self" } */ + +int +fn1 (void) +{ + int i = i; + return i; +} + +int +fn2 () +{ + const int j = j; + return j; +} + +int +fn3 () +{ + /* ??? Do we want this warning in C++? Probably not with -Wno-init-self. */ + volatile int k = k; /* { dg-warning "used uninitialized" "" { target c++ } } */ + return k; +} + +int +fn4 () +{ + const volatile int l = l; /* { dg-warning "used uninitialized" "" { target c++ } } */ + return l; +} diff --git a/gcc/testsuite/c-c++-common/Winit-self2.c b/gcc/testsuite/c-c++-common/Winit-self2.c new file mode 100644 index 00000000000..13aa9efdf26 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Winit-self2.c @@ -0,0 +1,31 @@ +/* PR middle-end/102633 */ +/* { dg-do compile } */ +/* { dg-options "-Wuninitialized -Winit-self" } */ + +int +fn1 (void) +{ + int i = i; /* { dg-warning "used uninitialized" } */ + return i; +} + +int +fn2 () +{ + const int j = j; /* { dg-warning "used uninitialized" } */ + return j; +} + +int +fn3 () +{ + volatile int k = k; /* { dg-warning "used uninitialized" } */ + return k; +} + +int +fn4 () +{ + const volatile int l = l; /* { dg-warning "used uninitialized" } */ + return l; +}