From patchwork Thu May 17 21:25:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom Tromey X-Patchwork-Id: 27320 Received: (qmail 11125 invoked by alias); 17 May 2018 21:25:48 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 11110 invoked by uid 89); 17 May 2018 21:25:47 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.9 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=gdbserver, serverkillexp, UD:server-kill.exp, gdb.server X-HELO: gateway33.websitewelcome.com Received: from gateway33.websitewelcome.com (HELO gateway33.websitewelcome.com) (192.185.146.195) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 17 May 2018 21:25:45 +0000 Received: from cm16.websitewelcome.com (cm16.websitewelcome.com [100.42.49.19]) by gateway33.websitewelcome.com (Postfix) with ESMTP id 01BB75AF2B for ; Thu, 17 May 2018 16:25:40 -0500 (CDT) Received: from box5379.bluehost.com ([162.241.216.53]) by cmsmtp with SMTP id JQP5f3qaWWCOCJQP5fuSL0; Thu, 17 May 2018 16:25:39 -0500 X-Authority-Reason: nr=8 Received: from 174-29-44-154.hlrn.qwest.net ([174.29.44.154]:55038 helo=bapiya) by box5379.bluehost.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1fJQP5-003pT8-Ou; Thu, 17 May 2018 16:25:39 -0500 From: Tom Tromey To: Tom Tromey Cc: gdb-patches@sourceware.org Subject: Re: [RFA] Show padding in ptype/o output References: <20180517212307.29102-1-tom@tromey.com> Date: Thu, 17 May 2018 15:25:38 -0600 In-Reply-To: <20180517212307.29102-1-tom@tromey.com> (Tom Tromey's message of "Thu, 17 May 2018 15:23:07 -0600") Message-ID: <87vabm2cvh.fsf@tromey.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 X-BWhitelist: no X-Source-L: No X-Exim-ID: 1fJQP5-003pT8-Ou X-Source-Sender: 174-29-44-154.hlrn.qwest.net (bapiya) [174.29.44.154]:55038 X-Source-Auth: tom+tromey.com X-Email-Count: 2 X-Source-Cap: ZWx5bnJvYmk7ZWx5bnJvYmk7Ym94NTM3OS5ibHVlaG9zdC5jb20= X-Local-Domain: yes >>>>> "Tom" == Tom Tromey writes: Tom> I was recently using ptype/o to look at the layout of some objects in Tom> gdb. I noticed that trailing padding was not shown -- but I wanted to Tom> be able to look at that, too. Tom> This patch changes ptype/o to also print trailing holes. Oops, I forgot to squash those commits and only sent the test suite change. Here's the real patch. Tom commit f4c9741648a991f4591b290000214a9dbaf8099a Author: Tom Tromey Date: Sat May 12 17:04:50 2018 -0600 Show padding in ptype/o output I was recently using ptype/o to look at the layout of some objects in gdb. I noticed that trailing padding was not shown -- but I wanted to be able to look at that, too. This patch changes ptype/o to also print trailing holes. Tested on x86-64 Fedora 26. gdb/ChangeLog 2018-05-17 Tom Tromey * c-typeprint.c (maybe_print_hole): New function. (c_print_type_struct_field_offset): Update. (c_type_print_base_struct_union): Call maybe_print_hole. gdb/testsuite/ChangeLog 2018-05-17 Tom Tromey * gdb.base/ptype-offsets.exp: Update. diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 4ae46c1ae4..759ce08577 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,11 @@ 2018-05-17 Tom Tromey + * c-typeprint.c (maybe_print_hole): New function. + (c_print_type_struct_field_offset): Update. + (c_type_print_base_struct_union): Call maybe_print_hole. + +2018-05-17 Tom Tromey + * extension.h (struct ext_lang_type_printers) : Initialize. diff --git a/gdb/c-typeprint.c b/gdb/c-typeprint.c index 1a8af78669..cb793f0770 100644 --- a/gdb/c-typeprint.c +++ b/gdb/c-typeprint.c @@ -937,6 +937,42 @@ c_print_type_union_field_offset (struct type *type, unsigned int field_idx, fprintf_filtered (stream, "/* %4u */", TYPE_LENGTH (ftype)); } +/* Helper function for ptype/o implementation that prints information + about a hole, if necessary. STREAM is where to print. BITPOS is + the bitpos of the current field. PODATA is the offset-printing + state. FOR_WHAT is a string describing the purpose of the + hole. */ + +static void +maybe_print_hole (struct ui_file *stream, unsigned int bitpos, + struct print_offset_data *podata, const char *for_what) +{ + /* We check for PODATA->END_BITPOS > 0 because there is a specific + scenario when PODATA->END_BITPOS can be zero and BITPOS can be > + 0: when we are dealing with a struct/class with a virtual method. + Because of the vtable, the first field of the struct/class will + have an offset of sizeof (void *) (the size of the vtable). If + we do not check for PODATA->END_BITPOS > 0 here, GDB will report + a hole before the first field, which is not accurate. */ + if (podata->end_bitpos > 0 && podata->end_bitpos < bitpos) + { + /* If PODATA->END_BITPOS is smaller than the current type's + bitpos, it means there's a hole in the struct, so we report + it here. */ + unsigned int hole = bitpos - podata->end_bitpos; + unsigned int hole_byte = hole / TARGET_CHAR_BIT; + unsigned int hole_bit = hole % TARGET_CHAR_BIT; + + if (hole_bit > 0) + fprintf_filtered (stream, "/* XXX %2u-bit %s */\n", hole_bit, + for_what); + + if (hole_byte > 0) + fprintf_filtered (stream, "/* XXX %2u-byte %s */\n", hole_byte, + for_what); + } +} + /* Print information about field at index FIELD_IDX of the struct type TYPE. @@ -963,28 +999,7 @@ c_print_type_struct_field_offset (struct type *type, unsigned int field_idx, unsigned int fieldsize_byte = TYPE_LENGTH (ftype); unsigned int fieldsize_bit = fieldsize_byte * TARGET_CHAR_BIT; - /* We check for PODATA->END_BITPOS > 0 because there is a specific - scenario when PODATA->END_BITPOS can be zero and BITPOS can be > - 0: when we are dealing with a struct/class with a virtual method. - Because of the vtable, the first field of the struct/class will - have an offset of sizeof (void *) (the size of the vtable). If - we do not check for PODATA->END_BITPOS > 0 here, GDB will report - a hole before the first field, which is not accurate. */ - if (podata->end_bitpos > 0 && podata->end_bitpos < bitpos) - { - /* If PODATA->END_BITPOS is smaller than the current type's - bitpos, it means there's a hole in the struct, so we report - it here. */ - unsigned int hole = bitpos - podata->end_bitpos; - unsigned int hole_byte = hole / TARGET_CHAR_BIT; - unsigned int hole_bit = hole % TARGET_CHAR_BIT; - - if (hole_bit > 0) - fprintf_filtered (stream, "/* XXX %2u-bit hole */\n", hole_bit); - - if (hole_byte > 0) - fprintf_filtered (stream, "/* XXX %2u-byte hole */\n", hole_byte); - } + maybe_print_hole (stream, bitpos, podata, "hole"); if (TYPE_FIELD_PACKED (type, field_idx)) { @@ -1508,6 +1523,9 @@ c_type_print_base_struct_union (struct type *type, struct ui_file *stream, { if (show > 0) { + unsigned int bitpos = TYPE_LENGTH (type) * TARGET_CHAR_BIT; + maybe_print_hole (stream, bitpos, podata, "padding"); + fputs_filtered ("\n", stream); print_spaces_filtered_with_print_options (level + 4, stream, diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index b18d4b6743..03fd99bf41 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2018-05-17 Tom Tromey + + * gdb.base/ptype-offsets.exp: Update. + 2018-05-15 Maciej W. Rozycki * gdb.server/server-kill.exp: Verify whether `server_pid' exists diff --git a/gdb/testsuite/gdb.base/ptype-offsets.exp b/gdb/testsuite/gdb.base/ptype-offsets.exp index 003e294a74..d8718d581b 100644 --- a/gdb/testsuite/gdb.base/ptype-offsets.exp +++ b/gdb/testsuite/gdb.base/ptype-offsets.exp @@ -52,6 +52,7 @@ gdb_test "ptype /o struct abc" \ { /\* total size \(bytes\): 8 \*/} \ { \} field8;} \ {/\* 48 | 4 \*/ my_int_type field9;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -81,6 +82,7 @@ gdb_test "ptype /oTM struct abc" \ { ~abc\(\);} \ {} \ { typedef int my_int_type;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -105,6 +107,7 @@ gdb_test "ptype /TMo struct abc" \ { /\* total size \(bytes\): 8 \*/} \ { \} field8;} \ {/\* 48 | 4 \*/ my_int_type field9;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -133,6 +136,7 @@ gdb_test "ptype /o struct pqr" \ { \} ff2;} \ {/\* XXX 28-byte hole \*/} \ {/\* 72 | 1 \*/ signed char ff3;} \ +{/\* XXX 7-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -148,6 +152,7 @@ gdb_test "ptype /o union qwe" \ {/\* XXX 4-byte hole \*/} \ {/\* 8 | 8 \*/ signed char \*a2;} \ {/\* 16 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} fff1;} \ @@ -161,6 +166,7 @@ gdb_test "ptype /o union qwe" \ {/\* XXX 4-byte hole \*/} \ {/\* 24 | 8 \*/ signed char \*a2;} \ {/\* 32 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} f4;} \ @@ -184,6 +190,7 @@ gdb_test "ptype /o struct poi" \ {/\* XXX 4-byte hole \*/} \ {/\* 16 | 8 \*/ signed char \*a2;} \ {/\* 24 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} fff1;} \ @@ -197,9 +204,11 @@ gdb_test "ptype /o struct poi" \ {/\* XXX 4-byte hole \*/} \ {/\* 32 | 8 \*/ signed char \*a2;} \ {/\* 40 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} f4;} \ +{/\* XXX 32-byte padding \*/} \ {} \ { /\* total size \(bytes\): 40 \*/} \ { \} fff2;} \ @@ -221,6 +230,7 @@ gdb_test "ptype /o struct poi" \ {/\* XXX 4-byte hole \*/} \ {/\* 112 | 8 \*/ signed char \*a2;} \ {/\* 120 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} f4;} \ @@ -228,6 +238,7 @@ gdb_test "ptype /o struct poi" \ { /\* total size \(bytes\): 40 \*/} \ { \} ff2;} \ {/\* 152 | 1 \*/ signed char ff3;} \ +{/\* XXX 7-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \} f4;} \ @@ -262,6 +273,7 @@ gdb_test "ptype /o struct tyu" \ {/\* 8 | 8 \*/ int64_t a5;} \ {/\* 16:27 | 4 \*/ int a6 : 5;} \ {/\* 16:56 | 8 \*/ int64_t a7 : 3;} \ +{/\* XXX 7-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \}}]