Re: [PATCH] [gdb/symtab] Keep track of all parents for cooked index
Andrew Burgess <[email protected]>
| Newsgroups | gmane.comp.gdb.patches |
|---|---|
| Message-ID | <[email protected]> |
I wanted to check if this fixed a bug I ran into, so I updated this patch and reposted it here: https://inbox.sourceware.org/gdb-patches/4c16f81081452e05f47741be7a2d15a250827c52.1787152777.git.aburgess@redhat.com Thanks, Andrew Tom de Vries <[email protected]> writes: > [ This is a resubmission of v2 of "[gdb/symtab] Keep track of all parents for > cooked index" [1], this time with a DWARF assembly test-case. > > The test-case is based on the DWARF info generated for test-case > gdb.cp/breakpoint-locs.exp with target board cc-with-dwz. > > The difference is that the test-case does not contain > DW_TAG_inlined_subroutine, which makes it possible to submit this patch > independently from the patch series. > > A consequence of this difference is that the relevant DIEs in the PU are not > named, and consequently have no entries in the cooked index, which meant that > the original fix didn't work, so the fix has been updated to handle this case > as well. ] > > Consider the new DWARF assembly test-case gdb.dwarf2/dwz-2.exp. > > With readnow, we have: > ... > $ gdb -q -batch -readnow outputs/gdb.dwarf2/dwz-2/dwz-2 \ > -ex "print ns::foo" \ > -ex "print ns::bar" > $1 = {int (void)} 0x4101ac <ns::foo()> > $2 = {int (void)} 0x4101b4 <ns::bar()> > ... > but with the cooked index we have either: > ... > $1 = {int (void)} 0x4101ac <ns::foo()> > No symbol "bar" in namespace "ns". > ... > or: > ... > No symbol "foo" in namespace "ns". > $1 = {int (void)} 0x4101b4 <ns::bar()> > ... > > The problem is that both the entries for foo and bar don't have the correct > parent: > ... > $ gdb -q -batch outputs/gdb.dwarf2/dwz-2/dwz-2 -ex "maint print objfiles" \ > | egrep "qualified:.*(foo|bar)$" > qualified: foo > qualified: bar > ... > so gdb ends up expanding the first CU that contains namespace ns, which is the > CU that won the import race for the PU, which is why we're getting either > ns::foo or ns::bar. > > So why are the foo and bar entries not getting the correct parent? > > The DWARF representation of ns::foo and ns::bar is as follows: we have the foo > DIE (in CU1): > ... > <1><42>: Abbrev Number: 3 (DW_TAG_subprogram) > <43> DW_AT_specification: <0x2a> > <47> DW_AT_name : foo > <4b> DW_AT_low_pc : 0x4101ac > <53> DW_AT_high_pc : 0x4101b4 > <5b> DW_AT_linkage_name: _ZN2ns3fooEv > ... > and the bar DIE (in CU2): > ... > <1><7b>: Abbrev Number: 3 (DW_TAG_subprogram) > <7c> DW_AT_specification: <0x2a> > <80> DW_AT_name : bar > <84> DW_AT_low_pc : 0x4101b4 > <8c> DW_AT_high_pc : 0x4101bc > <94> DW_AT_linkage_name: _ZN2ns3barEv > ... > both referring to this DIE (in the PU): > ... > <1><2a>: Abbrev Number: 5 (DW_TAG_subprogram) > <2b> DW_AT_specification: <0x23> > ... > which refers to this DIE (also in the PU): > ... > <1><1f>: Abbrev Number: 3 (DW_TAG_namespace) > <20> DW_AT_name : ns > <2><23>: Abbrev Number: 4 (DW_TAG_subprogram) > <24> DW_AT_type : <0x18> > <28> DW_AT_external : 1 > ... > > When processing both the foo and bar DIEs, finding the parent is deferred, but > when the deferred parents are resolved there is no entry at 0x2a in the parent > map: > ... > map start: > 0x0000000000000000 0x0 > 0x0000000000000020 0x31f497c0 (0x1f: ns) > 0x000000000000002a 0x0 > ... > > Fix this by adding an entry at 0x2a in the parent map, such that we have > instead: > ... > map start: > 0x0000000000000000 0x0 > 0x0000000000000020 0x321117c0 (0x1f: ns) > 0x000000000000002b 0x0 > 0x0000000000000042 0x321117c0 (0x1f: ns) > 0x0000000000000043 0x0 > 0x000000000000007b 0x321117c0 (0x1f: ns) > 0x000000000000007c 0x0 > ... > and: > ... > $ gdb -q -batch outputs/gdb.dwarf2/dwz-2/dwz-2 -ex "maint print objfiles" \ > | egrep "qualified:.*(foo|bar)$" > qualified: ns::foo > qualified: ns::bar > ... > and: > ... > $ gdb -q -batch outputs/gdb.dwarf2/dwz-2/dwz-2 \ > -ex "print ns::foo" \ > -ex "print ns::bar" > $1 = {int (void)} 0x4101ac <ns::foo()> > $2 = {int (void)} 0x4101b4 <ns::bar()> > ... > > Tested on aarch64-linux. > > PR symtab/32299 > Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32299 > > [1] https://sourceware.org/pipermail/gdb-patches/2023-December/205056.html > --- > gdb/dwarf2/read.c | 8 ++ > gdb/testsuite/gdb.dwarf2/dwz-2.c | 37 +++++++++ > gdb/testsuite/gdb.dwarf2/dwz-2.exp | 116 +++++++++++++++++++++++++++++ > 3 files changed, 161 insertions(+) > create mode 100644 gdb/testsuite/gdb.dwarf2/dwz-2.c > create mode 100644 gdb/testsuite/gdb.dwarf2/dwz-2.exp > > diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c > index 6ac6f7c6a39..cacfab7e6d5 100644 > --- a/gdb/dwarf2/read.c > +++ b/gdb/dwarf2/read.c > @@ -16601,6 +16601,14 @@ cooked_indexer::index_dies (cutu_reader *reader, > this_parent_entry, m_per_cu); > } > > + if (this_parent_entry != nullptr) > + { > + parent_map::addr_type addr > + = parent_map::form_addr (this_die, > + reader->cu->per_cu->is_dwz); > + m_die_range_map->add_entry (addr, addr, this_parent_entry); > + } > + > if (linkage_name != nullptr) > { > /* We only want this to be "main" if it has a linkage name > diff --git a/gdb/testsuite/gdb.dwarf2/dwz-2.c b/gdb/testsuite/gdb.dwarf2/dwz-2.c > new file mode 100644 > index 00000000000..7b3236e980a > --- /dev/null > +++ b/gdb/testsuite/gdb.dwarf2/dwz-2.c > @@ -0,0 +1,37 @@ > +/* This testcase is part of GDB, the GNU debugger. > + > + Copyright 2024 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/>. */ > + > +int > +foo (void) > +{ > + asm ("foo_label: .globl foo_label"); > + return 1; > +} > + > +int > +bar (void) > +{ > + asm ("bar_label: .globl bar_label"); > + return 2; > +} > + > +int > +main() > +{ > + asm ("main_label: .globl main_label"); > + return 0; > +} > diff --git a/gdb/testsuite/gdb.dwarf2/dwz-2.exp b/gdb/testsuite/gdb.dwarf2/dwz-2.exp > new file mode 100644 > index 00000000000..17508926340 > --- /dev/null > +++ b/gdb/testsuite/gdb.dwarf2/dwz-2.exp > @@ -0,0 +1,116 @@ > +# Copyright 2024 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/>. > + > +# Check that the cooked index gets the correct parents for some entries with > +# the parents in a partial unit. > +# > +# The structure is similar to what's generated for test-case > +# gdb.cp/breakpoint-locs.exp with gcc and target board cc-with-dwz, only in > +# that case we have: > +# DW_TAG_inlined_subroutine -ao-> decl DW_TAG_subprogram -s-> > +# (DW_TAG_namespace::DW_TAG_class_type::decl DW_TAG_subprogram) > +# and here we use: > +# DW_TAG_subprogram -s-> decl DW_TAG_subprogram -s-> > +# (DW_TAG_namespace::decl DW_TAG_subprogram) > + > +load_lib dwarf.exp > + > +# This test can only be run on targets which support DWARF-2 and use gas. > +require dwarf2_support > + > +standard_testfile .c dwz.S > + > +# Create the DWARF. > +set asm_file [standard_output_file $srcfile2] > +Dwarf::assemble $asm_file { > + get_func_info foo > + get_func_info bar > + get_func_info main > + > + declare_labels partial_label int_label decl1 decl2 > + > + cu {} { > + partial_label: partial_unit {} { > + int_label: base_type { > + {name int} > + {byte_size 4 sdata} > + {encoding @DW_ATE_signed} > + } > + > + DW_TAG_namespace { > + {DW_AT_name ns} > + } { > + decl1: subprogram { > + {type :$int_label} > + {external 1 flag} > + } > + } > + > + decl2: subprogram { > + {DW_AT_specification %$decl1} > + } > + } > + } > + > + cu {} { > + compile_unit {{language @DW_LANG_C_plus_plus}} { > + imported_unit { > + {import $partial_label ref_addr} > + } > + > + subprogram { > + {DW_AT_specification %$decl2} > + {DW_AT_name foo} > + {DW_AT_low_pc $foo_start DW_FORM_addr} > + {DW_AT_high_pc $foo_end DW_FORM_addr} > + {DW_AT_linkage_name _ZN2ns3fooEv} > + } > + } > + } > + > + cu {} { > + compile_unit {{language @DW_LANG_C_plus_plus}} { > + imported_unit { > + {import $partial_label ref_addr} > + } > + > + subprogram { > + {DW_AT_specification %$decl2} > + {DW_AT_name bar} > + {DW_AT_low_pc $bar_start DW_FORM_addr} > + {DW_AT_high_pc $bar_end DW_FORM_addr} > + {DW_AT_linkage_name _ZN2ns3barEv} > + } > + > + subprogram { > + {DW_AT_name main} > + {DW_AT_low_pc $main_start DW_FORM_addr} > + {DW_AT_high_pc $main_end DW_FORM_addr} > + } > + } > + } > +} > + > +if { [prepare_for_testing "failed to prepare" $testfile \ > + [list $asm_file $srcfile] {nodebug}] } { > + return -1 > +} > + > +# Regression test for PR32299. These should both pass, but before the fix > +# only one of them passed. > +gdb_test "p ns::foo" \ > + [string_to_regexp " <ns::foo()>"] > +gdb_test "p ns::bar" \ > + [string_to_regexp " <ns::bar()>"] > > base-commit: 86b26b453f65404b29ce035a2eb3d62671aa0612 > -- > 2.35.3