From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id 271773850425 for ; Fri, 13 May 2022 17:00:19 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 271773850425 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 24DFjUKi002450; Fri, 13 May 2022 17:00:14 GMT Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3g1t8p1dc6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 13 May 2022 17:00:13 +0000 Received: from m0098404.ppops.net (m0098404.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 24DGxo0Z003832; Fri, 13 May 2022 17:00:13 GMT Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3g1t8p1dbk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 13 May 2022 17:00:13 +0000 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 24DGiDDO008239; Fri, 13 May 2022 17:00:12 GMT Received: from b01cxnp23032.gho.pok.ibm.com (b01cxnp23032.gho.pok.ibm.com [9.57.198.27]) by ppma04dal.us.ibm.com with ESMTP id 3fwgdaxfr3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 13 May 2022 17:00:11 +0000 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 24DH0BFT23659002 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 13 May 2022 17:00:11 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 13D0212405A; Fri, 13 May 2022 17:00:11 +0000 (GMT) Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 49797124060; Fri, 13 May 2022 17:00:10 +0000 (GMT) Received: from li-e362e14c-2378-11b2-a85c-87d605f3c641.ibm.com (unknown [9.163.17.60]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 13 May 2022 17:00:10 +0000 (GMT) Message-ID: <3069b9009d09bb26a4b1878070e250993262636c.camel@us.ibm.com> Subject: [PING][PATCH,v5] Fix reverse stepping multiple contiguous PC ranges over the line table From: Carl Love To: Bruno Larsen , Luis Machado , gdb-patches@sourceware.org Cc: rogealve@br.ibm.com, Will Schmidt , cel@us.ibm.com Date: Fri, 13 May 2022 10:00:08 -0700 In-Reply-To: <65abc453edc9d73df97a8630503420ebf8c5747b.camel@us.ibm.com> References: <20220506085506.9184-1-luis.machado@arm.com> <9e420536-01e0-7192-d585-747c52fdf4d5@redhat.com> <65abc453edc9d73df97a8630503420ebf8c5747b.camel@us.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-18.el8) X-TM-AS-GCONF: 00 X-Proofpoint-GUID: NnvrqIwfaSUNBg121ACixSIGiO-MblBh X-Proofpoint-ORIG-GUID: tQcFvEJ-0BRXRVPPoDagehw1Ty6dF4Av Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 2 URL's were un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-13_08,2022-05-13_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 bulkscore=0 clxscore=1015 adultscore=0 mlxscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 spamscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2205130071 X-Spam-Status: No, score=-11.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, KAM_ASCII_DIVIDERS, KAM_SHORT, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, 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: 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, 13 May 2022 17:00:22 -0000 GDB maintainers: We have addressed the comments from Bruno. Unfortunately, Bruno is not a maintainer and can't give approval for the patch. We are hoping a maintainer can review the patch and provide us feedback. Thank you for your time. Carl Love --------------------------------------------------- On Fri, 2022-05-06 at 09:48 -0700, Carl Love via Gdb-patches wrote: > Bruno, GDB maintainers: > > The patch has been updated per the comments on the testcase from > Bruno. > > The patch was retested on Power 10 to ensure the test still works > correctly. > > Please let us know if there are any additional comments or if the > patch > is ready to commit. We thank you for your help with this patch. > > Carl Love > -------------------------------------------------------- > Fix reverse stepping multiple contiguous PC ranges over the line > table > v5:- Updated test case comments on the purpose of the test.- Add test > to check system supports record-replay.- Removed now unnecessary > reord > test when activating record. > v4:- Updated testcase to make it a bit longer so it can exercise > reverse-stepping multiple times.- Cleaned up debugging prints. > v3:- Updated testcase. The format for writing the DWARF program body > in the testcase expect file changed. See commit > gdb/testsuite/dwarf: > simplify line number program syntax (commit > d4c4a2298cad06ca71cfef725f5248f68205f0be) > v2:- Check if both the line and symtab match for a particular line > table entry. > -- > When running GDB's testsuite on aarch64-linux/Ubuntu 20.04 (also > spotted onthe ppc backend), I noticed some failures in > gdb.reverse/solib-precsave.expand gdb.reverse/solib-reverse.exp. > The failure happens around the following code: > 38 b[1] = shr2(17); /* middle part two */40 b[0] = > 6; b[1] = 9; /* generic statement, end part two */42 shr1 > ("message > 1\n"); /* shr1 one */ > Normal execution: > - step from line 38 will land on line 40.- step from line 40 will > land > on line 42. > Reverse execution: > - step from line 42 will land on line 40.- step from line 40 will > land > on line 40.- step from line 40 will land on line 38. > The problem here is that line 40 contains two contiguous but > distinctPC > ranges in the line table, like so: > Line 40 - [0x7ec ~ 0x7f4]Line 40 - [0x7f4 ~ 0x7fc] > The two distinct ranges are generated because GCC started outputting > sourcecolumn information, which GDB doesn't take into account at the > moment. > When stepping forward from line 40, we skip both of these ranges and > land online 42. When stepping backward from line 42, we stop at the > start PC of thesecond (or first, going backwards) range of line 40. > This happens because we have this check in > infrun.c:process_event_stop_test: > /* When stepping backward, stop at beginning of line range > (unless it's the function entry point, in which case keep going > back to the call point). */ CORE_ADDR stop_pc = ecs- > > event_thread->stop_pc (); if (stop_pc == ecs->event_thread- > > control.step_range_start && stop_pc != ecs->stop_func_start > && execution_direction == EXEC_REVERSE) end_stepping_range > (ecs); else keep_going (ecs); > Since we've reached ecs->event_thread->control.step_range_start, we > stopstepping backwards. > The right thing to do is to look for adjacent PC ranges for the same > line,until we notice a line change. Then we take that as the start PC > of therange. > Another solution I thought about is to merge the contiguous ranges > whenwe are reading the line tables. Though I'm not sure if we really > want to processthat data as opposed to keeping it as the compiler > created, and then workingaround that. > In any case, the following patch addresses this problem. > Validated on aarch64-linux and x86_64/Ubuntu 20.04/18.04. Carl Love > hasverified that it does fix a similar issue on ppc. > Ubuntu 18.04 doesn't actually run into these failures because the > compilerdoesn't generate distinct PC ranges for the same line. > I see similar failures on x86_64 in the gdb.reverse > tests(gdb.reverse/step-reverse.exp and gdb.reverse/step-reverse.exp). > Those arealso fixed by this patch. > The included testcase (based on a test Carl wrote) exercises this > problem forArm, ppc and x86. It shows full passes with the patch > applied. > Co-authored-by: Carl Love --- > gdb/infrun.c | 22 ++- > gdb/symtab.c | 49 ++++++ > gdb/symtab.h | 16 ++ > gdb/testsuite/gdb.reverse/map-to-same-line.c | 55 +++++++ > .../gdb.reverse/map-to-same-line.exp | 141 > ++++++++++++++++++ > 5 files changed, 282 insertions(+), 1 deletion(-) create mode 100644 > gdb/testsuite/gdb.reverse/map-to-same-line.c create mode 100644 > gdb/testsuite/gdb.reverse/map-to-same-line.exp > diff --git a/gdb/infrun.c b/gdb/infrun.cindex > 6e5853ef42a..82c28961aeb > 100644--- a/gdb/infrun.c+++ b/gdb/infrun.c@@ -6955,11 +6955,31 @@ if > (ecs->event_thread->control.proceed_to_finish have software > watchpoints). */ ecs->event_thread->control.may_range_step = > 1; > + /* When we are stepping inside a particular line range, in > reverse,+ and we are sitting at the first address of that range, > we need to+ check if this address also shows up in another line > range as the+ end address.++ If so, we need to check what line > such > a step range points to.+ If it points to the same line as the > current step range, that+ means we need to keep going in order > to reach the first address+ of the line range. We repeat this > until we eventually get to the+ first address of a particular > line > we're stepping through. */+ CORE_ADDR range_start = ecs- > > event_thread->control.step_range_start;+ if > > (execution_direction > == EXEC_REVERSE)+ {+ gdb::optional > real_range_start+ = find_line_range_start (ecs->event_thread- > > stop_pc ());++ if (real_range_start.has_value ())+ > > range_start > = *real_range_start;+ }+ /* When stepping backward, stop at > beginning of line range (unless it's the function entry point, > in which case keep going back to the call > point). */ CORE_ADDR stop_pc = ecs->event_thread->stop_pc > ();- if (stop_pc == ecs->event_thread- > > control.step_range_start+ if (stop_pc == range_start && > stop_pc != ecs->stop_func_start && execution_direction == > EXEC_REVERSE) end_stepping_range (ecs);diff --git > a/gdb/symtab.c > b/gdb/symtab.cindex 4b33d6c91af..de4cb5dd0eb 100644--- > a/gdb/symtab.c+++ b/gdb/symtab.c@@ -3433,6 +3433,55 @@ find_pc_line > (CORE_ADDR pc, int notcurrent) return sal; } +/* Compare two > symtab_and_line entries. Return true if both have+ the same line > number and the same symtab pointer. That means we+ are dealing > with > two entries from the same line and from the same+ source > file.++ Return false otherwise. */++static > bool+sal_line_symtab_matches_p (const symtab_and_line &sal1,+ > const symtab_and_line &sal2)+{+ return (sal1.line == > sal2.line && sal1.symtab == sal2.symtab);+}++/* See > symtah.h. */++gdb::optional+find_line_range_start > (CORE_ADDR pc)+{+ struct symtab_and_line current_sal = find_pc_line > (pc, 0);++ if (current_sal.line == 0)+ return {};++ struct > symtab_and_line prev_sal = find_pc_line (current_sal.pc - 1, > 0);++ /* > If the previous entry is for a different line, that means we are > already+ at the entry with the start PC for this line. */+ if > (!sal_line_symtab_matches_p (prev_sal, current_sal))+ return > current_sal.pc;++ /* Otherwise, keep looking for entries for the > same > line but with+ smaller PC's. */+ bool done = false;+ CORE_ADDR > prev_pc;+ while (!done)+ {+ prev_pc = > prev_sal.pc;++ prev_sal = find_pc_line (prev_pc - 1, > 0);++ /* > Did we notice a line change? If so, we are done with the > search. */+ if (!sal_line_symtab_matches_p (prev_sal, > current_sal))+ done = true;+ }++ return prev_pc;+}+ /* See > symtab.h. */ struct symtab *diff --git a/gdb/symtab.h > b/gdb/symtab.hindex b1cf84f756f..226fe8803db 100644--- > a/gdb/symtab.h+++ b/gdb/symtab.h@@ -2285,6 +2285,22 @@ extern struct > symtab_and_line find_pc_line (CORE_ADDR, int); extern struct > symtab_and_line find_pc_sect_line (CORE_ADDR, > > struct obj_section *, int); +/* Given PC, and assuming > it is part of a range of addresses that is part of a+ line, go back > through the linetable and find the starting PC of > that+ line.++ For > example, suppose we have 3 PC ranges for line X:++ Line X - [0x0 - > 0x8]+ Line X - [0x8 - 0x10]+ Line X - [0x10 - 0x18]++ If we > call > the function with PC == 0x14, we want to return 0x0, as that > is+ the > starting PC of line X, and the ranges are contiguous.+*/++extern > gdb::optional find_line_range_start (CORE_ADDR pc);+ /* > Wrapper around find_pc_line to just return the symtab. */ extern > struct symtab *find_pc_line_symtab (CORE_ADDR);diff --git > a/gdb/testsuite/gdb.reverse/map-to-same-line.c > b/gdb/testsuite/gdb.reverse/map-to-same-line.cnew file mode > 100644index > 00000000000..dd9f9f8a400--- /dev/null+++ > b/gdb/testsuite/gdb.reverse/map-to-same-line.c@@ -0,0 +1,55 @@+/* > Copyright 2022 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 < > http://www.gnu.org/licenses/ > >. */++/* The purpose of this test is to create a DWARF line table > that contains two+ or more entries for the same line. When > stepping > (forwards or backwards),+ GDB should step over the entire line and > not just a particular entry in the+ line table. */++int+main > ()+{ /* TAG: main prologue */+ asm ("main_label: .globl > main_label");+ int i = 1, j = 2, k;+ float f1 = 2.0, f2 = 4.1, > f3;+ const char *str_1 = "foo", *str_2 = "bar", *str_3;++ asm > ("line1: .globl line1");+ k = i; f3 = f1; str_3 = str_1; /* TAG: > line 1 */++ asm ("line2: .globl line2");+ k = j; f3 = f2; str_3 = > str_2; /* TAG: line 2 */++ asm ("line3: .globl line3");+ k = i; > f3 > = f1; str_3 = str_1; /* TAG: line 3 */++ asm ("line4: .globl > line4");+ k = j; f3 = f2; str_3 = str_2; /* TAG: line 4 */++ asm > ("line5: .globl line5");+ k = i; f3 = f1; str_3 = str_1; /* TAG: > line 5 */++ asm ("line6: .globl line6");+ k = j; f3 = f2; str_3 = > str_2; /* TAG: line 6 */++ asm ("line7: .globl line7");+ k = i; > f3 > = f1; str_3 = str_1; /* TAG: line 7 */++ asm ("line8: .globl > line8");+ k = j; f3 = f2; str_3 = str_2; /* TAG: line 8 */++ asm > ("main_return: .globl main_return");+ return 0; /* TAG: main return > */+}diff --git a/gdb/testsuite/gdb.reverse/map-to-same-line.exp > b/gdb/testsuite/gdb.reverse/map-to-same-line.expnew file mode > 100644index 00000000000..c3fb859be55--- /dev/null+++ > b/gdb/testsuite/gdb.reverse/map-to-same-line.exp@@ -0,0 +1,141 @@+# > Copyright 2022 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 < > http://www.gnu.org/licenses/ > >.++# When stepping (forwards or backwards), GDB should step over > the > entire line+# and not just a particular entry in the line table. This > test was added to+# verify the find_line_range_start function > properly > sets the step range for a+# line that consists of multiple > statements, > i.e. multiple entries in the line+# table. This test creates a DWARF > line table that contains two entries for+# the same line to do the > needed testing.++load_lib dwarf.exp++# This test can only be run on > targets which support DWARF-2 and use gas.+if {![dwarf2_support]} > {+ unsupported "dwarf2 support required for this test"+ return > 0+}++if [get_compiler_info] {+ return -1+}++# The DWARF assembler > requires the gcc compiler.+if {!$gcc_compiled} {+ unsupported "gcc > is required for this test"+ return 0+}++# This test suitable only > for process record-replay+if ![supports_process_record] > {+ return+}++standard_testfile .c .S++if { [prepare_for_testing > "failed to prepare" ${testfile} ${srcfile}] } {+ return -1+}++set > asm_file [standard_output_file $srcfile2]+Dwarf::assemble $asm_file > {+ global srcdir subdir srcfile+ declare_labels integer_label > L++ # Find start address and length of program+ lassign > [function_range main [list ${srcdir}/${subdir}/$srcfile]] \+ main_st > art main_len+ set main_end "$main_start + $main_len"++ cu {} {+ > > compile_unit {+ {language @DW_LANG_C}+ {name > map-to-same- > line.c}+ {stmt_list $L DW_FORM_sec_offset}+ {low_pc 0 > addr}+ } {+ subprogram {+ {external 1 > flag}+ > {name main}+ {low_pc $main_start addr}+ > {high_pc $main_len DW_FORM_data4}+ }+ }+ }++ lines > {version 2 default_is_stmt 1} L {+ include_dir > "${srcdir}/${subdir}"+ file_name "$srcfile" 1++ # Generate > the > line table program with distinct source lines being+ # mapped to the > same line entry. Line 1, 5 and 8 contain 1 statement+ # each. Line 2 > contains 2 statements. Line 3 contains 3 statements.+ program > {+ > DW_LNE_set_address $main_start+ line [gdb_get_line_number > "TAG: main prologue"]+ DW_LNS_copy+ DW_LNE_set_addres > s > line1+ line [gdb_get_line_number "TAG: line 1" ]+ D > W_LNS_copy > + DW_LNE_set_address line2+ line [gdb_get_line_number > "TAG: line 2" ]+ DW_LNS_copy+ DW_LNE_set_address > line3+ line [gdb_get_line_number "TAG: line 2" ]+ D > W_LNS_copy > + DW_LNE_set_address line4+ line [gdb_get_line_number > "TAG: line 3" ]+ DW_LNS_copy+ DW_LNE_set_address > line5+ line [gdb_get_line_number "TAG: line 3" ]+ D > W_LNS_copy > + DW_LNE_set_address line6+ line [gdb_get_line_number > "TAG: line 3" ]+ DW_LNS_copy+ DW_LNE_set_address > line7+ line [gdb_get_line_number "TAG: line 5" ]+ D > W_LNS_copy > + DW_LNE_set_address line8+ line [gdb_get_line_number > "TAG: line 8" ]+ DW_LNS_copy+ DW_LNE_set_address > main_return+ line [gdb_get_line_number "TAG: main return"]+ > DW_LNS_copy+ DW_LNE_end_sequence+ }+ }+}++if { > [prepare_for_testing "failed to prepare" ${testfile} \+ [list > $srcfile > $asm_file] {nodebug} ] } {+ return -1+}++if ![runto_main] > {+ return -1+}++# Activate process > record/replay+gdb_test_no_output > "record" "turn on process record"++gdb_test "tbreak main_return" > "Temporary breakpoint .*" "breakpoint at return"+gdb_test "continue" > "Temporary breakpoint .*" "run to end of main"++# At this point, GDB > has already recorded the execution up until the return+# > statement. Reverse-step and test if GDB transitions between lines in > the+# expected order. It should reverse-step across lines 8, 5, 3, 2 > and 1.+foreach line {8 5 3 2 1} {+ gdb_test "reverse-step" ".*TAG: > line $line.*" "reverse step to line $line"+}-- 2.31.1 > >