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 4348D3858C27 for ; Fri, 5 Mar 2021 06:35:30 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 4348D3858C27 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 [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 30B7BAC54 for ; Fri, 5 Mar 2021 06:35:29 +0000 (UTC) Subject: [PING^2][PATCH][gdb/breakpoints] Workaround missing line-table entry From: Tom de Vries To: gdb-patches@sourceware.org References: <20210122091509.GA30312@delia> <22fce456-c018-649f-2d20-9d950dc6062a@suse.de> Message-ID: <38281254-82de-1e7d-bf38-c00ecf62fbd9@suse.de> Date: Fri, 5 Mar 2021 07:35:28 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <22fce456-c018-649f-2d20-9d950dc6062a@suse.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-11.5 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, KAM_STOCKGEN, 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: Fri, 05 Mar 2021 06:35:31 -0000 On 2/5/21 11:07 AM, Tom de Vries wrote: > On 1/22/21 10:15 AM, Tom de Vries wrote: >> Hi, >> >> When running test-case gdb.opt/inline-cmds.exp, we run into this KFAIL with >> gcc: >> ... >> Breakpoint 7, main () at gdb.opt/inline-cmds.c:71^M >> 71 result = 0; /* set breakpoint 3 here */^M >> (gdb) PASS: gdb.opt/inline-cmds.exp: continue to breakpoint: consecutive func1 >> next^M >> 73 func1 (); /* first call */^M >> (gdb) PASS: gdb.opt/inline-cmds.exp: next to first func1 >> next^M >> 75 marker ();^M >> (gdb) KFAIL: gdb.opt/inline-cmds.exp: next to second func1 (PRMS: gdb/25884) >> ... >> while with clang we have instead: >> ... >> next^M >> 74 func1 (); /* second call */^M >> (gdb) PASS: gdb.opt/inline-cmds.exp: next to second func1 >> ... >> >> The relevant bit of the test source is here in inline-cmds.c: >> ... >> 71 result = 0; /* set breakpoint 3 here */ >> 72 >> 73 func1 (); /* first call */ >> 74 func1 (); /* second call */ >> 75 marker (); >> ... >> with func1 defined as: >> ... >> 33 inline __attribute__((always_inline)) int func1(void) >> 34 { >> 35 bar (); >> 36 return x * y; >> 37 } >> ... >> >> The corresponding insns are: >> ... >> 40050b: movl $0x0,0x200b1f(%rip) # 601034 >> 400515: callq 40057b >> 40051a: callq 40057b >> 40051f: callq 400596 >> ... >> and the line number info is: >> ... >> Line number Starting address View Stmt >> 71 0x40050b x >> 35 0x400515 x >> 75 0x40051f x >> ... >> >> The line number info is missing an entry for the insn at 40051a, and that is >> causing the FAIL. This is a gcc issue, filed as PR gcc/98780 -" Missing line >> table entry for inlined stmt at -g -O0". >> >> [ For contrast, with clang we have an extra entry: >> ... >> Line number Starting address View Stmt >> 71 0x40050b x >> 35 0x400515 x >> 35 0x40051a >> 75 0x40051f x >> ... >> though it appears to be missing the start-of-statement marker. ] >> >> However, there is debug info that indicates that the insn at 40051a is not >> part of the line table entry for the insn at 400515: >> ... >> <2><1c4>: Abbrev Number: 8 (DW_TAG_inlined_subroutine) >> <1c5> DW_AT_abstract_origin: <0x2a2> >> <1c9> DW_AT_low_pc : 0x400515 >> <1d1> DW_AT_high_pc : 0x5 >> <1d9> DW_AT_call_file : 1 >> <1da> DW_AT_call_line : 73 >> <2><1db>: Abbrev Number: 8 (DW_TAG_inlined_subroutine) >> <1dc> DW_AT_abstract_origin: <0x2a2> >> <1e0> DW_AT_low_pc : 0x40051a >> <1e8> DW_AT_high_pc : 0x5 >> <1f0> DW_AT_call_file : 1 >> <1f1> DW_AT_call_line : 74 >> ... >> and indeed lldb manages to "next" from line 73 to line 74. >> >> Work around the missing line table entry, by using the inline frame info to >> narrow the stepping range in prepare_one_step. >> >> Tested on x86_64-linux. >> >> Any comments? >> Ping. Thanks, - Tom >> [gdb/breakpoints] Workaround missing line-table entry >> >> gdb/ChangeLog: >> >> 2021-01-22 Tom de Vries >> >> PR breakpoints/25884 >> * infcmd.c (prepare_one_step): Using inline frame info to narrow >> stepping range. >> >> gdb/testsuite/ChangeLog: >> >> 2021-01-22 Tom de Vries >> >> PR breakpoints/25884 >> * gdb.opt/inline-cmds.exp: Remove kfail. >> >> --- >> gdb/infcmd.c | 14 ++++++++++++++ >> gdb/testsuite/gdb.opt/inline-cmds.exp | 17 +---------------- >> 2 files changed, 15 insertions(+), 16 deletions(-) >> >> diff --git a/gdb/infcmd.c b/gdb/infcmd.c >> index 6f0ed952de6..ecb3de31879 100644 >> --- a/gdb/infcmd.c >> +++ b/gdb/infcmd.c >> @@ -1009,6 +1009,20 @@ prepare_one_step (thread_info *tp, struct step_command_fsm *sm) >> &tp->control.step_range_start, >> &tp->control.step_range_end); >> >> + /* There's a problem in gcc (PR gcc/98780) that causes missing line >> + table entries, which results in a too large stepping range. >> + Use inlined_subroutine info to make the range more narrow. */ >> + if (inline_skipped_frames (tp) > 0) >> + { >> + symbol *sym = inline_skipped_symbol (tp); >> + if (SYMBOL_CLASS (sym) == LOC_BLOCK) >> + { >> + const block *block = SYMBOL_BLOCK_VALUE (sym); >> + if (BLOCK_END (block) < tp->control.step_range_end) >> + tp->control.step_range_end = BLOCK_END (block); >> + } >> + } >> + >> tp->control.may_range_step = 1; >> >> /* If we have no line info, switch to stepi mode. */ >> diff --git a/gdb/testsuite/gdb.opt/inline-cmds.exp b/gdb/testsuite/gdb.opt/inline-cmds.exp >> index 17720c46795..981dcbb4a29 100644 >> --- a/gdb/testsuite/gdb.opt/inline-cmds.exp >> +++ b/gdb/testsuite/gdb.opt/inline-cmds.exp >> @@ -222,22 +222,7 @@ gdb_breakpoint $line3 >> gdb_continue_to_breakpoint "consecutive func1" >> >> gdb_test "next" ".*func1 .*first call.*" "next to first func1" >> -set msg "next to second func1" >> -gdb_test_multiple "next" $msg { >> - -re ".*func1 .*second call.*$gdb_prompt $" { >> - pass $msg >> - } >> - -re ".*marker .*$gdb_prompt $" { >> - # This assembles to two consecutive call instructions. >> - # Both appear to be at the same line, because they're >> - # in the body of the same inlined function. This is >> - # reasonable for the line table. GDB should take the >> - # containing block and/or function into account when >> - # deciding how far to step. The single line table entry >> - # is actually two consecutive instances of the same line. >> - kfail gdb/25884 $msg >> - } >> -} >> +gdb_test "next" ".*func1 .*second call.*" "next to second func1" >> >> # It is easier when the two inlined functions are not on the same line. >> set line4 [gdb_get_line_number "set breakpoint 4 here"] >>