From patchwork Wed Jun 22 11:50:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vit Kabele X-Patchwork-Id: 55272 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 22F3538337A7 for ; Wed, 22 Jun 2022 11:51:06 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from mail.sysgo.com (mail.sysgo.com [159.69.174.51]) by sourceware.org (Postfix) with ESMTPS id 0C72A3833792 for ; Wed, 22 Jun 2022 11:50:34 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0C72A3833792 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=sysgo.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=sysgo.com Date: Wed, 22 Jun 2022 13:50:31 +0200 From: Vit Kabele To: pinskia@gmail.com Subject: [PATCH v2] c: Extend the -Wpadded message with actual padding size Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-12.8 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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: , Cc: polacek@redhat.com, vit@kabele.me, gcc-patches@gcc.gnu.org Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" Hello, I added the ! default_packed directive, and now the test is properly skipped on the targets with that property. I tested with cris-elf target and the test behaves properly. Best regards, Vit Kabele -- >8 -- Subject: [PATCH v2] c: Extend the -Wpadded message with actual padding size When the compiler warns about padding struct to alignment boundary, it now also informs the user about the size of the alignment that needs to be added to get rid of the warning. This removes the need of using pahole or similar tools, or manually determining the padding size. Tested for x86_64-pc-linux-gnu and cris-elf targets. gcc/ChangeLog: * stor-layout.cc (finalize_record_size): Extend warning message. gcc/testsuite/ChangeLog: * c-c++-common/Wpadded.c: New test. Signed-off-by: Vit Kabele --- gcc/stor-layout.cc | 7 ++++++- gcc/testsuite/c-c++-common/Wpadded.c | 13 +++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/c-c++-common/Wpadded.c diff --git a/gcc/stor-layout.cc b/gcc/stor-layout.cc index 765f22f68b9..88923c4136b 100644 --- a/gcc/stor-layout.cc +++ b/gcc/stor-layout.cc @@ -1781,7 +1781,12 @@ finalize_record_size (record_layout_info rli) && simple_cst_equal (unpadded_size, TYPE_SIZE (rli->t)) == 0 && input_location != BUILTINS_LOCATION && !TYPE_ARTIFICIAL (rli->t)) - warning (OPT_Wpadded, "padding struct size to alignment boundary"); + { + tree pad_size + = size_binop (MINUS_EXPR, TYPE_SIZE_UNIT (rli->t), unpadded_size_unit); + warning (OPT_Wpadded, + "padding struct size to alignment boundary with %E bytes", pad_size); + } if (warn_packed && TREE_CODE (rli->t) == RECORD_TYPE && TYPE_PACKED (rli->t) && ! rli->packed_maybe_necessary diff --git a/gcc/testsuite/c-c++-common/Wpadded.c b/gcc/testsuite/c-c++-common/Wpadded.c new file mode 100644 index 00000000000..9e7e9f240c1 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Wpadded.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-options "-Wpadded" } */ + +/* + * The struct is on single line, because C++ compiler emits the -Wpadded + * warning at the first line of the struct definition, while the C compiler at + * the last line. This way the test passes on both. + * + * The test is skipped on targets where default behavior is to pack the + * structs because there is no warning triggered. + */ +struct S { __UINT32_TYPE__ i; char c; } foo; /* { dg-warning "padding struct size to alignment boundary with 3 bytes" "" { target { ! default_packed } } } */ +