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gdb: don't display inferior list for pending breakpoints

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I noticed that in the 'info breakpoints' output, GDB sometimes prints
the inferior list for pending breakpoints, this doesn't seem right to
me.  A pending breakpoint has no locations (at least, as far as we
display things in the 'info breakpoints' output), so including an
inferior list seems odd.

Here's what I see right now:

  (gdb) info breakpoint 5
  Num     Type           Disp Enb Address            What
  5       breakpoint     keep y   <PENDING>          foo inf 1
  (gdb)

It's the 'inf 1' at the end of the line that I'm objecting too.

To trigger this behaviour we need to be in a multi-inferior debug
session.  The breakpoint must have been non-pending at some point in
the past, and so have a location assigned to it.

The breakpoint becomes pending again as a result of a shared library
being unloaded.  When this happens the location itself is marked
pending (via bp_location::shlib_disabled).

In print_one_breakpoint_location, in order to print the inferior list
we check that the breakpoint has a location, and that we have multiple
inferiors, but we don't check if the location itself is pending.

This commit adds that check, which means the output is now:

  (gdb) info breakpoint 5
  Num     Type           Disp Enb Address            What
  5       breakpoint     keep y   <PENDING>          foo
  (gdb)

Which I think makes more sense -- indeed, the format without the
inferior list is what we display for a pending breakpoint that has
never had any locations assigned, so I think this change in behaviour
makes GDB more consistent.
This commit is contained in:
Andrew Burgess
2023-04-13 15:12:17 +01:00
parent 9f26b04c3e
commit 7934cb137a
4 changed files with 215 additions and 1 deletions
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2
gdb/breakpoint.c
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@@ -6592,7 +6592,7 @@ print_one_breakpoint_location (struct breakpoint *b,
}
}
if (loc != NULL && !header_of_multiple)
if (loc != nullptr && !header_of_multiple && !loc->shlib_disabled)
{
std::vector<int> inf_nums;
int mi_only = 1;

22
gdb/testsuite/gdb.multi/pending-bp-lib.c Normal file
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@@ -0,0 +1,22 @@
/* Copyright 2023-2024 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 global_var = 0;
void
foo (int arg)
{
global_var = arg;
}

66
gdb/testsuite/gdb.multi/pending-bp.c Normal file
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@@ -0,0 +1,66 @@
/* Copyright 2023-2024 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/>. */
#include <dlfcn.h>
#include <stdlib.h>
void
breakpt (void)
{
/* Nothing. */
}
volatile int global_counter = 0;
volatile int call_count = 1;
int
main (void)
{
void *handle;
void (*func)(int);
/* Some filler work so that we don't initially stop on the breakpt call
below. */
++global_counter;
breakpt (); /* Break before open. */
/* Now load the shared library. */
handle = dlopen (SHLIB_NAME, RTLD_LAZY);
if (handle == NULL)
abort ();
breakpt (); /* Break after open. */
/* Find the function symbol. */
func = (void (*)(int)) dlsym (handle, "foo");
for (; call_count > 0; --call_count)
{
/* Call the library function. */
func (1);
}
breakpt (); /* Break before close. */
/* Unload the shared library. */
if (dlclose (handle) != 0)
abort ();
breakpt (); /* Break after close. */
return 0;
}

126
gdb/testsuite/gdb.multi/pending-bp.exp Normal file
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@@ -0,0 +1,126 @@
# Copyright 2023-2024 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/>.
# Tests related to pending breakpoints in a multi-inferior environment.
require allow_shlib_tests !use_gdb_stub
standard_testfile
set libname $testfile-lib
set srcfile_lib $srcdir/$subdir/$libname.c
set binfile_lib [standard_output_file $libname.so]
if { [gdb_compile_shlib $srcfile_lib $binfile_lib {}] != "" } {
untested "failed to compile shared library 1"
return -1
}
set binfile_lib_target [gdb_download_shlib $binfile_lib]
if { [build_executable "failed to prepare" $testfile $srcfile \
[list debug \
additional_flags=-DSHLIB_NAME=\"$binfile_lib_target\" \
shlib_load]] } {
return -1
}
# Start two inferiors, both running the same test binary. The arguments
# INF_1_STOP and INF_2_STOP are source code patterns that are passed to
# gdb_get_line_number to figure out where each inferior should be stopped.
#
# This proc does a clean_restart and leaves inferior 2 selected. Also the
# 'breakpoint pending' flag is enabled, so pending breakpoints can be created
# without GDB prompting the user.
proc do_test_setup { inf_1_stop inf_2_stop } {
clean_restart ${::binfile}
gdb_locate_shlib $::binfile_lib
if {![runto_main]} {
return false
}
gdb_breakpoint [gdb_get_line_number ${inf_1_stop}] temporary
gdb_continue_to_breakpoint "move inferior 1 into position"
gdb_test "add-inferior -exec ${::binfile}" \
"Added inferior 2.*" "add inferior 2"
gdb_test "inferior 2" "Switching to inferior 2 .*" "switch to inferior 2"
if {![runto_main]} {
return false
}
gdb_breakpoint [gdb_get_line_number ${inf_2_stop}] temporary
gdb_continue_to_breakpoint "move inferior 2 into position"
gdb_test_no_output "set breakpoint pending on"
return true
}
# Check that when a breakpoint is in the pending state, but that breakpoint
# does have some locations (those locations themselves are pending), GDB
# doesn't display the inferior list in the 'info breakpoints' output.
proc_with_prefix test_no_inf_display {} {
do_test_setup "Break before open" "Break before open"
# Create a breakpoint on 'foo'. As the shared library (that
# contains foo) has not been loaded into any inferior yet, then
# there will be no locations and the breakpoint will be created
# pending. Pass the 'allow-pending' flag so the gdb_breakpoint
# correctly expects the new breakpoint to be pending.
gdb_breakpoint "foo" allow-pending
set bpnum [get_integer_valueof "\$bpnum" "*INVALID*" \
"get foo breakpoint number"]
# Check the 'info breakpoints' output; the breakpoint is pending with
# no 'inf X' appearing at the end of the line.
gdb_test "info breakpoint $bpnum" \
"$bpnum\\s+breakpoint\\s+keep\\s+y\\s+<PENDING>\\s+foo" \
"check info bp before locations have been created"
# Now select inferior 1 and allow the inferior to run forward to the
# point where a breakpoint location for foo will have been created.
gdb_test "inferior 1" "Switching to inferior 1 .*"
gdb_breakpoint [gdb_get_line_number "Break after open"] temporary
gdb_continue_to_breakpoint \
"move inferior 1 until a location has been added"
# Check the 'info breakpoints' output. Notice we display the inferior
# list at the end of the breakpoint line.
gdb_test "info breakpoint $bpnum" \
"$bpnum\\s+breakpoint\\s+keep\\s+y\\s+$::hex\\s+<foo\[^>\]*>\\s+inf 1" \
"check info breakpoints while breakpoint is inserted"
# Continue inferior 1 until the shared library has been unloaded. The
# breakpoint on 'foo' will return to the pending state. We will need to
# 'continue' twice as the first time will hit the 'foo' breakpoint.
gdb_breakpoint [gdb_get_line_number "Break after close"] temporary
gdb_continue_to_breakpoint "hit the breakpoint in foo"
gdb_continue_to_breakpoint "after close library"
# Check the 'info breakpoints' output, check there is no 'inf 1' at the
# end of the breakpoint line.
gdb_test "info breakpoint $bpnum" \
[multi_line \
"$bpnum\\s+breakpoint\\s+keep\\s+y\\s+<PENDING>\\s+foo" \
"\\s+breakpoint already hit 1 time"] \
"check info breakpoints while breakpoint is pending"
}
# Run all the tests.
test_no_inf_display