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 C0A723857C7A for ; Thu, 16 Jul 2020 17:49:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org C0A723857C7A 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 B6A9AADD6; Thu, 16 Jul 2020 17:49:29 +0000 (UTC) Date: Thu, 16 Jul 2020 19:49:23 +0200 From: Tom de Vries To: gdb-patches@sourceware.org Subject: [PATCH][gdb/symtab] Ignore zero line table entries Message-ID: <20200716174922.GA8508@delia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-Spam-Status: No, score=-11.1 required=5.0 tests=BAYES_00, GIT_PATCH_0, 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: Thu, 16 Jul 2020 17:49:28 -0000 Hi, The DWARF standard states for the line register in the line number information state machine the following: ... An unsigned integer indicating a source line number. Lines are numbered beginning at 1. The compiler may emit the value 0 in cases where an instruction cannot be attributed to any source line. ... So, it's possible to have a zero line number in the DWARF line table. This is currently not handled by GDB. The zero value is read in as any other line number, but internally the zero value has a special meaning: end-of-sequence, so the line table entry ends up having a different interpretation than intended in some situations. I've created a test-case where various aspects are tested, which has these 4 interesting tests. 1. Next-step through a zero-line instruction, is_stmt == 1 gdb.dwarf2/dw2-line-number-zero.exp: bar1, 2nd next 2. Next-step through a zero-line instruction, is_stmt == 0 gdb.dwarf2/dw2-line-number-zero.exp: bar2, 2nd next 3. Show source location at zero-line instruction, is_stmt == 1 gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar1_label_3 4. Show source location at zero-line instruction, is_stmt == 0 gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar2_label_3 And we have the following results: 8.3.1, 9.2: ... FAIL: gdb.dwarf2/dw2-line-number-zero.exp: bar1, 2nd next PASS: gdb.dwarf2/dw2-line-number-zero.exp: bar2, 2nd next PASS: gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar1_label_3 FAIL: gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar2_label_3 ... commit 8c95582da8 "gdb: Add support for tracking the DWARF line table is-stmt field": ... PASS: gdb.dwarf2/dw2-line-number-zero.exp: bar1, 2nd next PASS: gdb.dwarf2/dw2-line-number-zero.exp: bar2, 2nd next FAIL: gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar1_label_3 FAIL: gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar2_label_3 ... commit d8cc8af6a1 "[gdb/symtab] Fix line-table end-of-sequence sorting", master: FAIL: gdb.dwarf2/dw2-line-number-zero.exp: bar1, 2nd next FAIL: gdb.dwarf2/dw2-line-number-zero.exp: bar2, 2nd next PASS: gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar1_label_3 PASS: gdb.dwarf2/dw2-line-number-zero.exp: continue to breakpoint: bar2_label_3 ... The regression in test 2 at commit d8cc8af6a1 was filed as PR symtab/26243, where clang emits zero line numbers. The way to fix all tests is to make sure line number zero internally doesn't clash with special meaning values, and by handling it appropriately everywhere. That however looks too intrusive for the GDB 10 release. Instead, we decide to ensure defined behaviour for line number zero by ignoring it. This gives us back the test results from before commit d8cc8af6a1, fixing PR26243. We mark the FAILs for tests 3 and 4 as KFAILs. Test 4 was already failing for the 9.2 release, and we consider the regression of test 3 from gdb 9.2 to gdb 10 the cost for having defined behaviour. Build and reg-tested on x86_64-linux. Any comments? Thanks, - Tom [gdb/symtab] Ignore zero line table entries gdb/ChangeLog: 2020-07-16 Tom de Vries PR symtab/26243 * dwarf2/read.c (lnp_state_machine::record_line): Ignore zero line entries. gdb/testsuite/ChangeLog: 2020-07-16 Tom de Vries PR symtab/26243 * gdb.dwarf2/dw2-line-number-zero.c: New test. * gdb.dwarf2/dw2-line-number-zero.exp: New file. --- gdb/dwarf2/read.c | 5 +- gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.c | 62 +++++++++ gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.exp | 162 ++++++++++++++++++++++ 3 files changed, 227 insertions(+), 2 deletions(-) diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 558fad74f8..93f522c1f1 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -20300,8 +20300,9 @@ lnp_state_machine::record_line (bool end_sequence) bool file_changed = m_last_subfile != m_cu->get_builder ()->get_current_subfile (); bool ignore_this_line - = (file_changed && !end_sequence && m_last_address == m_address - && !m_is_stmt && m_stmt_at_address); + = ((file_changed && !end_sequence && m_last_address == m_address + && !m_is_stmt && m_stmt_at_address) + || (!end_sequence && m_line == 0)); if ((file_changed && !ignore_this_line) || end_sequence) { diff --git a/gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.c b/gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.c new file mode 100644 index 0000000000..15b37a6676 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.c @@ -0,0 +1,62 @@ +/* + Copyright 2020 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +void +foo (int x) +{ + +} + +void +bar1 (void) +{ + asm ("bar1_label: .globl bar1_label"); + foo (1); + asm ("bar1_label_2: .globl bar1_label_2"); + foo (2); + asm ("bar1_label_3: .globl bar1_label_3"); + foo (3); + asm ("bar1_label_4: .globl bar1_label_4"); + foo (4); + asm ("bar1_label_5: .globl bar1_label_5"); +} + +void +bar2 (void) +{ + asm ("bar2_label: .globl bar2_label"); + foo (1); + asm ("bar2_label_2: .globl bar2_label_2"); + foo (2); + asm ("bar2_label_3: .globl bar2_label_3"); + foo (3); + asm ("bar2_label_4: .globl bar2_label_4"); + foo (4); + asm ("bar2_label_5: .globl bar2_label_5"); +} + +int +main (void) +{ + asm ("main_label: .globl main_label"); + + bar1 (); + + bar2 (); + + return 0; +} + diff --git a/gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.exp b/gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.exp new file mode 100644 index 0000000000..e322f77708 --- /dev/null +++ b/gdb/testsuite/gdb.dwarf2/dw2-line-number-zero.exp @@ -0,0 +1,162 @@ +# Copyright 2020 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . +load_lib dwarf.exp + +# This test can only be run on targets which support DWARF-2 and use gas. +if {![dwarf2_support]} { + verbose "Skipping dw2-line-number-zero test." + return 0 +} + +# The .c files use __attribute__. +if [get_compiler_info] { + return -1 +} +if !$gcc_compiled { + verbose "Skipping dw2-line-number-zero test." + return 0 +} + +standard_testfile .c dw2-line-number-zero-dw.S + +set asm_file [standard_output_file $srcfile2] +Dwarf::assemble $asm_file { + global srcdir subdir srcfile srcfile2 + declare_labels Llines + + # Find start address and length for our functions. + set main_func \ + [function_range main [list ${srcdir}/${subdir}/$srcfile]] + set main_start [lindex $main_func 0] + set main_length [lindex $main_func 1] + + set bar1_func \ + [function_range bar1 [list ${srcdir}/${subdir}/$srcfile]] + set bar1_start [lindex $bar1_func 0] + set bar1_length [lindex $bar1_func 1] + + set bar2_func \ + [function_range bar2 [list ${srcdir}/${subdir}/$srcfile]] + set bar2_start [lindex $bar2_func 0] + set bar2_length [lindex $bar2_func 1] + + cu {} { + compile_unit { + {language @DW_LANG_C} + {name dw2-line-number-zero.c} + {stmt_list $Llines DW_FORM_sec_offset} + } { + subprogram { + {external 1 flag} + {name main} + {low_pc $main_start addr} + {high_pc "$main_start + $main_length" addr} + } + subprogram { + {external 1 flag} + {name bar1} + {low_pc $bar1_start addr} + {high_pc "$bar1_start + $bar1_length" addr} + } + subprogram { + {external 1 flag} + {name bar2} + {low_pc $bar2_start addr} + {high_pc "$bar2_start + $main_length" addr} + } + } + } + + lines {version 2} Llines { + include_dir "${srcdir}/${subdir}" + file_name "$srcfile" 1 + + program { + {DW_LNE_set_address bar1_label} + {line 27} + {DW_LNS_copy} + + {DW_LNE_set_address bar1_label_2} + {line 29} + {DW_LNS_copy} + + {DW_LNE_set_address bar1_label_3} + {line 0} + {DW_LNS_copy} + + {DW_LNE_set_address bar1_label_4} + {line 33} + {DW_LNS_copy} + + {DW_LNE_set_address bar1_label_5} + {DW_LNE_end_sequence} + + + {DW_LNE_set_address bar2_label} + {line 41} + {DW_LNS_copy} + + {DW_LNE_set_address bar2_label_2} + {line 43} + {DW_LNS_copy} + + {DW_LNE_set_address bar2_label_3} + {line 0} + {DW_LNS_negate_stmt} + {DW_LNS_copy} + {DW_LNS_negate_stmt} + + {DW_LNE_set_address bar2_label_4} + {line 47} + {DW_LNS_copy} + + {DW_LNE_set_address bar2_label_5} + {DW_LNE_end_sequence} + } + } +} + +if { [prepare_for_testing "failed to prepare" ${testfile} \ + [list $srcfile $asm_file] {nodebug}] } { + return -1 +} + +if ![runto_main] { + return -1 +} + +gdb_breakpoint "bar1" +gdb_continue_to_breakpoint "bar1" "\[^\r\n\]*:27\r\n.*" + +gdb_test "n" "foo \\(2\\);" "bar1, 1st next" +gdb_test "n" "foo \\(4\\);" "bar1, 2nd next" + +gdb_breakpoint "bar2" +gdb_continue_to_breakpoint "bar2" "\[^\r\n\]*:41\r\n.*" + +gdb_test "n" "foo \\(2\\);" "bar2, 1st next" +gdb_test "n" "foo \\(4\\);" "bar2, 2nd next" + +if ![runto_main] { + return -1 +} + +gdb_breakpoint "bar1_label_3" +setup_kfail "gdb/nnnnn" *-*-* +gdb_continue_to_breakpoint "bar1_label_3" "bar1 \\(\\)" + +gdb_breakpoint "bar2_label_3" +setup_kfail "gdb/nnnnn" *-*-* +gdb_continue_to_breakpoint "bar2_label_3" "bar2 \\(\\)"