From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by sourceware.org (Postfix) with ESMTPS id A9E0C395CC90 for ; Wed, 27 May 2020 15:33:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org A9E0C395CC90 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tdevries@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 7D1B0AD72; Wed, 27 May 2020 15:33:39 +0000 (UTC) Subject: Re: [RFC][PATCH 0/6] Step program considering the source column information To: Hannes Domani , gdb-patches@sourceware.org References: <20200516172632.4803-1-ssbssa.ref@yahoo.de> <20200516172632.4803-1-ssbssa@yahoo.de> From: Tom de Vries Autocrypt: addr=tdevries@suse.de; keydata= xsBNBF0ltCcBCADDhsUnMMdEXiHFfqJdXeRvgqSEUxLCy/pHek88ALuFnPTICTwkf4g7uSR7 HvOFUoUyu8oP5mNb4VZHy3Xy8KRZGaQuaOHNhZAT1xaVo6kxjswUi3vYgGJhFMiLuIHdApoc u5f7UbV+egYVxmkvVLSqsVD4pUgHeSoAcIlm3blZ1sDKviJCwaHxDQkVmSsGXImaAU+ViJ5l CwkvyiiIifWD2SoOuFexZyZ7RUddLosgsO0npVUYbl6dEMq2a5ijGF6/rBs1m3nAoIgpXk6P TCKlSWVW6OCneTaKM5C387972qREtiArTakRQIpvDJuiR2soGfdeJ6igGA1FZjU+IsM5ABEB AAHNH1RvbSBkZSBWcmllcyA8dGRldnJpZXNAc3VzZS5kZT7CwKsEEwEIAD4WIQSsnSe5hKbL MK1mGmjuhV2rbOJEoAUCXSW0JwIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgAAh CRDuhV2rbOJEoBYhBKydJ7mEpsswrWYaaO6FXats4kSgc48H/Ra2lq5p3dHsrlQLqM7N68Fo eRDf3PMevXyMlrCYDGLVncQwMw3O/AkousktXKQ42DPJh65zoXB22yUt8m0g12xkLax98KFJ 5NyUloa6HflLl+wQL/uZjIdNUQaHQLw3HKwRMVi4l0/Jh/TygYG1Dtm8I4o708JS4y8GQxoQ UL0z1OM9hyM3gI2WVTTyprsBHy2EjMOu/2Xpod95pF8f90zBLajy6qXEnxlcsqreMaqmkzKn 3KTZpWRxNAS/IH3FbGQ+3RpWkNGSJpwfEMVCeyK5a1n7yt1podd1ajY5mA1jcaUmGppqx827 8TqyteNe1B/pbiUt2L/WhnTgW1NC1QDOwE0EXSW0JwEIAM99H34Bu4MKM7HDJVt864MXbx7B 1M93wVlpJ7Uq+XDFD0A0hIal028j+h6jA6bhzWto4RUfDl/9mn1StngNVFovvwtfzbamp6+W pKHZm9X5YvlIwCx131kTxCNDcF+/adRW4n8CU3pZWYmNVqhMUiPLxElA6QhXTtVBh1RkjCZQ Kmbd1szvcOfaD8s+tJABJzNZsmO2hVuFwkDrRN8Jgrh92a+yHQPd9+RybW2l7sJv26nkUH5Z 5s84P6894ebgimcprJdAkjJTgprl1nhgvptU5M9Uv85Pferoh2groQEAtRPlCGrZ2/2qVNe9 XJfSYbiyedvApWcJs5DOByTaKkcAEQEAAcLAkwQYAQgAJhYhBKydJ7mEpsswrWYaaO6FXats 4kSgBQJdJbQnAhsMBQkDwmcAACEJEO6FXats4kSgFiEErJ0nuYSmyzCtZhpo7oVdq2ziRKD3 twf7BAQBZ8TqR812zKAD7biOnWIJ0McV72PFBxmLIHp24UVe0ZogtYMxSWKLg3csh0yLVwc7 H3vldzJ9AoK3Qxp0Q6K/rDOeUy3HMqewQGcqrsRRh0NXDIQk5CgSrZslPe47qIbe3O7ik/MC q31FNIAQJPmKXX25B115MMzkSKlv4udfx7KdyxHrTSkwWZArLQiEZj5KG4cCKhIoMygPTA3U yGaIvI/BGOtHZ7bEBVUCFDFfOWJ26IOCoPnSVUvKPEOH9dv+sNy7jyBsP5QxeTqwxC/1ZtNS DUCSFQjqA6bEGwM22dP8OUY6SC94x1G81A9/xbtm9LQxKm0EiDH8KBMLfQ== Message-ID: <56760df2-b642-c112-2a16-89320a2fba0e@suse.de> Date: Wed, 27 May 2020 17:33:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200516172632.4803-1-ssbssa@yahoo.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-12.3 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, KAM_SHORT, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 May 2020 15:33:39 -0000 On 16-05-2020 19:26, Hannes Domani via Gdb-patches wrote: > Basically, this implements the new commands nextc (nc) and stepc (sc), > which allow to step through the program until an instruction is reached, > that belongs to another source column (according to the debug information). > > The current column location is visualized in the frame info, and in the TUI. > > Also, the column information is added to 'maint info line-table' and the > python line table interface. > > Since the frame info output is different, this certainly breaks the > testsuite, so this column indicator needs a parameter to disable, but I > wasn't concerned about this yet. > > With the example code from PR25913, it looks like this: > > (gdb) start > Temporary breakpoint 2 at 0x40162d: file gdb-25911.c, line 4. > Starting program: C:\src\tests\gdb-25911.exe > > Temporary breakpoint 2, main () at gdb-25911.c:4 > 4 int a = 4; > ^ > (gdb) nc > 6 a = 5; a = 6; a = 7; > ^ > (gdb) nc > 6 a = 5; a = 6; a = 7; > ^ > (gdb) nc > 6 a = 5; a = 6; a = 7; > ^ > (gdb) nc > 8 return 0; > > > What do you think of this so far? > Very nice :) As I've just learned by looking at this ( https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95360 ) PR, interesting code in relation to this patch series is dwarf_record_line_p. The function implements filtering of line-table elements, and has as related test-case gdb.dwarf2/dw2-single-line-discriminators.exp. If we disable the filtering (by returning 1 at the end instead of 0), we get for test-case gdb.dwarf2/dw2-single-line-discriminators.exp: ... Temporary breakpoint 2, main () at gdb.dwarf2/dw2-single-line-discriminators.c:26 26 x = 0; (gdb) n 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ (gdb) si 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ... That is: no progress is visible after the stepi. If we re-enable the filtering, we have: ... Temporary breakpoint 1, main () at gdb.dwarf2/dw2-single-line-discriminators.c:26 26 x = 0; (gdb) n 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ (gdb) si 0x00000000004004cd 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ... So, progress is visible. If we now use your patch series, and with the filtering enabled, we have: ... Temporary breakpoint 1, main () at gdb.dwarf2/dw2-single-line-discriminators.c:26 26 x = 0; ^ (gdb) n 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) si 0x00000000004004cd 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) 0x00000000004004d1 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) 0x00000000004004d3 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) 0x00000000004004d5 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ ... So, we see progress in the insn addresses, but the column does not progress. OTOH, if we disable filtering: ... Temporary breakpoint 1, main () at gdb.dwarf2/dw2-single-line-discriminators.c:26 26 x = 0; ^ (gdb) n 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) si 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) si 0x00000000004004d1 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) si 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) si 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ (gdb) si 0x00000000004004d8 28 for (i = 0; i < 10; ++i) continue; /* stepi line */ ^ ... we don't see progress after the first stepi, but eventually we do see progress in the column. Looking at the line-info: ... [0x00000147] Set column to 8 [0x00000149] Special opcode 161: advance Address by 11 to 0x4004c6 and Line by 2 to 28 [0x0000014a] Extended opcode 4: set Discriminator to 4 [0x0000014e] Special opcode 103: advance Address by 7 to 0x4004cd and Line by 0 to 28 ... perhaps we we should collapse entries that have the same column, so something like this in dwarf_record_line_p: ... if (line != last_line) return 1; if (colum != last_column) return 1; return 0; ... Thanks, - Tom