gdb: only insert thread-specific breakpoints in the relevant inferior

This commit updates GDB so that thread or inferior specific
breakpoints are only inserted into the program space in which the
specific thread or inferior is running.

In terms of implementation, getting this basically working is easy
enough, now that a breakpoint's thread or inferior field is setup
prior to GDB looking for locations, we can easily use this information
to find a suitable program_space and pass this to as a filter when
creating the sals.

Or we could if breakpoint_ops::create_sals_from_location_spec allowed
us to pass in a filter program_space.

So, this commit extends breakpoint_ops::create_sals_from_location_spec
to take a program_space argument, and uses this to filter the set of
returned sals.  This accounts for about half the change in this patch.

The second set of changes starts from breakpoint_set_thread and
breakpoint_set_inferior, this is called when the thread or inferior
for a breakpoint changes, e.g. from the Python API.

Previously this call would never result in the locations of a
breakpoint changing, after all, locations were inserted in every
program space, and we just use the thread or inferior variable to
decide when we should stop.  Now though, changing a breakpoint's
thread or inferior can mean we need to figure out a new set of
breakpoint locations.

To support this I've added a new breakpoint_re_set_one function, which
is like breakpoint_re_set, but takes a single breakpoint, and just
updates the locations for that one breakpoint.  We only need to call
this function if the program_space in which a breakpoint's thread (or
inferior) is running actually changes.  If the program_space does
change then we call the new breakpoint_re_set_one function passing in
the program_space which should be used to filter the new locations (or
nullptr to indicate we should set locations in all program spaces).
This filter program_space needs to propagate down to all the re_set
methods, this accounts for the remaining half of the changes in this
patch.

There were a couple of existing tests that created thread or inferior
specific breakpoints and then checked the 'info breakpoints' output,
these needed updating.  These were:

  gdb.mi/user-selected-context-sync.exp
  gdb.multi/bp-thread-specific.exp
  gdb.multi/multi-target-continue.exp
  gdb.multi/multi-target-ping-pong-next.exp
  gdb.multi/tids.exp
  gdb.mi/new-ui-bp-deleted.exp
  gdb.multi/inferior-specific-bp.exp
  gdb.multi/pending-bp-del-inferior.exp

I've also added some additional tests to:

  gdb.multi/pending-bp.exp

I've updated the documentation and added a NEWS entry.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>

1 files changed, 206 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.multi/pending-bp.exp b/gdb/testsuite/gdb.multi/pending-bp.exp
index 13f76f4..2a0644b 100644
--- a/gdb/testsuite/gdb.multi/pending-bp.exp
+++ b/gdb/testsuite/gdb.multi/pending-bp.exp
@@ -72,6 +72,48 @@ proc do_test_setup { inf_1_stop inf_2_stop } {
     return true
 }
 
+# Create a breakpoint on the function 'foo' in THREAD.  It is expected
+# that the breakpoint created will be pending, this is checked by
+# running the 'info breakpoints' command.
+#
+# Returns the number for the newly created breakpoint.
+proc do_create_pending_foo_breakpoint { {thread "1.1"} } {
+    gdb_test "break foo thread $thread" \
+	[multi_line \
+	     "Function \"foo\" not defined\\." \
+	     "Breakpoint $::decimal \\(foo\\) pending\."] \
+	"set pending thread-specific breakpoint"
+    set bpnum [get_integer_valueof "\$bpnum" "*INVALID*" \
+		   "get number for thread-specific breakpoint on foo"]
+    gdb_test "info breakpoints $bpnum" \
+	[multi_line \
+	     "$bpnum\\s+breakpoint\\s+keep\\s+y\\s+<PENDING>\\s+foo" \
+	     "\\s+stop only in thread [string_to_regexp $thread]"] \
+	"check thread-specific breakpoint is initially pending"
+
+    return $bpnum
+}
+
+# Create a breakpoint on the function 'foo' in THREAD.  It is expected
+# that the breakpoint created will not be pending, this is checked by
+# running the 'info breakpoints' command.
+#
+# Returns the number for the newly created breakpoint.
+proc do_create_foo_breakpoint { {thread "1.1"} } {
+    gdb_test "break foo thread $thread" \
+	"Breakpoint $::decimal at $::hex" \
+	"set thread-specific breakpoint"
+    set bpnum [get_integer_valueof "\$bpnum" "*INVALID*" \
+		   "get number for thread-specific breakpoint on foo"]
+    gdb_test "info breakpoints $bpnum" \
+	[multi_line \
+	     "$bpnum\\s+breakpoint\\s+keep\\s+y\\s+$::hex\\s+<foo\[^>\]*> inf $::decimal" \
+	     "\\s+stop only in thread [string_to_regexp $thread]"] \
+	"check thread-specific breakpoint is initially pending"
+
+    return $bpnum
+}
+
 # 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.
@@ -122,5 +164,169 @@ proc_with_prefix test_no_inf_display {} {
 	"check info breakpoints while breakpoint is pending"
 }
 
+# Setup two inferiors.  In #1 the symbol 'foo' has not yet been
+# loaded, while in #2 the symbol 'foo' has been loaded.
+#
+# Create a thread-specific breakpoint on 'foo' tied to a thread in
+# inferior #1, the breakpoint should be pending -- 'foo' is not yet
+# loaded in #1.
+#
+# Now move inferior #1 forward until 'foo' is loaded, check the
+# breakpoint is no longer pending.
+#
+# Move inferior #1 forward more until 'foo' is unloaded, check that
+# the breakpoint returns to the pending state.
+proc_with_prefix test_pending_toggle { } {
+
+    do_test_setup "Break before open" "Break before close"
+
+    set bpnum [do_create_pending_foo_breakpoint]
+
+    # Now return to inferior 1 and continue until the shared library is
+    # loaded, the breakpoint should become non-pending.
+    gdb_test "inferior 1" "Switching to inferior 1 .*" \
+	"switch back to inferior 1"
+    gdb_continue_to_breakpoint "stop in foo in inferior 1" "foo \\(\\) .*"
+
+    gdb_test "info breakpoint $bpnum" \
+	[multi_line \
+	     "$bpnum\\s+breakpoint\\s+keep\\s+y\\s+$::hex <foo\[^>\]*> inf 1" \
+	     "\\s+stop only in thread 1\\.1" \
+	     "\\s+breakpoint already hit 1 time"] \
+	"check thread-specific breakpoint is no longer pending"
+
+    gdb_breakpoint [gdb_get_line_number "Break after close"] temporary
+    gdb_continue_to_breakpoint "close library"
+    gdb_test "info breakpoints $bpnum" \
+	[multi_line \
+	     "$bpnum\\s+breakpoint\\s+keep\\s+y\\s+<PENDING>\\s+foo" \
+	     "\\s+stop only in thread 1\\.1" \
+	     "\\s+breakpoint already hit 1 time"] \
+	"check thread-specific breakpoint is pending again"
+}
+
+# Create a Python variable VAR and set it to the gdb.Breakpoint object
+# corresponding to the breakpoint numbered BPNUM.  If THREAD is not
+# the empty string then THREAD should be an integer, check that
+# gdb.Breakpoint.thread is set to the value of THREAD.  Otherwise, if
+# THREAD is the empty string, check that gdb.Breakpoint.thread is set
+# to None.
+proc py_find_breakpoint { var bpnum {thread ""} } {
+    gdb_test_no_output \
+	"python ${var}=\[b for b in gdb.breakpoints() if b.number == $bpnum\]\[0\]" \
+	"find Python gdb.Breakpoint object"
+    if { $thread ne "" } {
+	gdb_test_no_output "python assert(${var}.thread == ${thread})" \
+	    "check thread attribute is currently correct"
+    } else {
+	gdb_test_no_output "python assert(${var}.thread is None)" \
+	    "check thread attribute is currently correct"
+    }
+}
+
+# Setup two inferiors.  In #1 the symbol 'foo' has not yet been
+# loaded, while in #2 the symbol 'foo' has been loaded.
+#
+# Create a thread-specific breakpoint on 'foo' tied to a thread in
+# inferior #1, the breakpoint should be pending -- 'foo' is not yet
+# loaded in #1.
+#
+# Use Python to change the thread of the thread-specific breakpoint to
+# a thread in inferior #2, at this point the thread should gain a
+# location and become non-pending.
+#
+# Set the thread back to a thread in inferior #1, the breakpoint
+# should return to the pending state.
+proc_with_prefix py_test_toggle_thread {} {
+    do_test_setup "Break before open" "Break after open"
+
+    set bpnum [do_create_pending_foo_breakpoint]
+
+    py_find_breakpoint "bp" $bpnum 1
+
+    gdb_test_no_output "python bp.thread = 2" \
+	"change thread on thread-specific breakpoint"
+    gdb_test "info breakpoint $bpnum" \
+	[multi_line \
+	     "$bpnum\\s+breakpoint\\s+keep\\s+y\\s+$::hex <foo\[^>\]*> inf 2" \
+	     "\\s+stop only in thread 2\\.1"] \
+	"check thread-specific breakpoint now has a location"
+
+    gdb_test_no_output "set call_count = 2" "set call_count in inferior 2"
+    gdb_continue_to_breakpoint "stop at foo in inferior 2" "foo \\(\\) .*"
+
+    gdb_test_no_output "python bp.thread = 1" \
+	"restore thread on thread-specific breakpoint"
+    gdb_test "info breakpoints $bpnum" \
+	[multi_line \
+	     "$bpnum\\s+breakpoint\\s+keep\\s+y\\s+<PENDING>\\s+foo" \
+	     "\\s+stop only in thread 1\\.1" \
+	     "\\s+breakpoint already hit 1 time"] \
+	"check thread-specific breakpoint has returned to pending"
+
+    gdb_breakpoint [gdb_get_line_number "Break after close"] temporary
+    gdb_continue_to_breakpoint "stop after close in inferior 2" \
+	".* Break after close\\. .*"
+
+    gdb_test "inferior 1" "Switching to inferior 1 .*" \
+	"switch to inferior 1"
+    gdb_continue_to_breakpoint "stop at foo in inferior 1" "foo \\(\\) .*"
+}
+
+# Setup two inferiors.  Both inferiors have the symbol 'foo'
+# available.
+#
+# Create a thread-specific breakpoint on 'foo' tied to a thread in
+# inferior #1, the breakpoint should not be pending, but will only
+# have a single location, the location in inferior #1.
+#
+# Use Python to change the thread of the thread-specific breakpoint to
+# None.  At this point the breakpoint should gain a second location, a
+# location in inferior #2.
+proc_with_prefix py_test_clear_thread {} {
+    do_test_setup "Break after open" "Break after open"
+
+    set bpnum [do_create_foo_breakpoint]
+
+    py_find_breakpoint "bp" $bpnum 1
+
+    gdb_test_no_output "python bp.thread = None" \
+	"clear thread on thread-specific breakpoint"
+    gdb_test "info breakpoints $bpnum" \
+	[multi_line \
+	     "${bpnum}\\s+breakpoint\\s+keep y\\s+<MULTIPLE>\\s*" \
+	     "${bpnum}\\.1\\s+y\\s+${::hex}\\s+<foo\[^>\]*> inf $::decimal" \
+	     "${bpnum}\\.2\\s+y\\s+${::hex}\\s+<foo\[^>\]*> inf $::decimal"] \
+	"check for a location in both inferiors"
+
+    gdb_continue_to_breakpoint "stop at foo in inferior 2" "foo \\(\\) .*"
+    gdb_test_no_output "set call_count = 2" "set call_count in inferior 2"
+
+    gdb_test "inferior 1" "Switching to inferior 1 .*" \
+	"switch to inferior 1"
+    gdb_continue_to_breakpoint "stop at foo in inferior 1" "foo \\(\\) .*"
+    gdb_test_no_output "set call_count = 2" "set call_count in inferior 1"
+
+    gdb_test_no_output "python bp.thread = 2"
+    gdb_test "info breakpoints $bpnum" \
+	[multi_line \
+	     "${bpnum}\\s+breakpoint\\s+keep y\\s+${::hex}\\s+<foo\[^>\]*> inf 2" \
+	     "\\s+stop only in thread 2\\.1" \
+	     "\\s+breakpoint already hit 2 times"] \
+	"check for a location only in inferior 2"
+
+    gdb_breakpoint [gdb_get_line_number "Break after close"] temporary
+    gdb_continue_to_breakpoint "stop after close in inferior 1" \
+	".* Break after close\\. .*"
+
+    gdb_test "inferior 2" "Switching to inferior 2 .*" \
+	"switch back to inferior 2"
+    gdb_continue_to_breakpoint "stop at foo again in inferior 2" \
+	"foo \\(\\) .*"
+}
+
 # Run all the tests.
 test_no_inf_display
+test_pending_toggle
+py_test_toggle_thread
+py_test_clear_thread