gdb/breakpoint: disable a bp location if condition is invalid at that location

Currently, for a conditional breakpoint, GDB checks if the condition
can be evaluated in the context of the first symtab and line (SAL).
In case of an error, defining the conditional breakpoint is aborted.
This prevents having a conditional breakpoint whose condition may
actually be meaningful for some of the location contexts.  This patch
makes it possible to define conditional BPs by checking all location
contexts.  If the condition is meaningful for even one context, the
breakpoint is defined.  The locations for which the condition gives
errors are disabled.

The bp_location struct is introduced a new field, 'disabled_by_cond'.
This field denotes whether the location is disabled automatically
because the condition was non-evaluatable.  Disabled-by-cond locations
cannot be enabled by the user.  But locations that are not
disabled-by-cond can be enabled/disabled by the user manually as
before.

For a concrete example, consider 3 contexts of a function 'func'.

  class Base
  {
  public:
    int b = 20;

    void func () {}
  };

  class A : public Base
  {
  public:
    int a = 10;

    void func () {}
  };

  class C : public Base
  {
  public:
    int c = 30;

    void func () {}
  };

Note that

* the variable 'a' is defined only in the context of A::func.
* the variable 'c' is defined only in the context of C::func.
* the variable 'b' is defined in all the three contexts.

With the existing GDB, it's not possible to define a conditional
breakpoint at 'func' if the condition refers to 'a' or 'c':

  (gdb) break func if a == 10
  No symbol "a" in current context.
  (gdb) break func if c == 30
  No symbol "c" in current context.
  (gdb) info breakpoints
  No breakpoints or watchpoints.

With this patch, it becomes possible:

  (gdb) break func if a == 10
  warning: failed to validate condition at location 1, disabling:
    No symbol "a" in current context.
  warning: failed to validate condition at location 3, disabling:
    No symbol "a" in current context.
  Breakpoint 1 at 0x11b6: func. (3 locations)
  (gdb) break func if c == 30
  Note: breakpoint 1 also set at pc 0x11ce.
  Note: breakpoint 1 also set at pc 0x11c2.
  Note: breakpoint 1 also set at pc 0x11b6.
  warning: failed to validate condition at location 1, disabling:
    No symbol "c" in current context.
  warning: failed to validate condition at location 2, disabling:
    No symbol "c" in current context.
  Breakpoint 2 at 0x11b6: func. (3 locations)
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
          stop only if a == 10
  1.1                         N*  0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  1.2                         y   0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  1.3                         N*  0x00000000000011ce in C::func() at condbreak-multi-context.cc:39
  2       breakpoint     keep y   <MULTIPLE>
          stop only if c == 30
  2.1                         N*  0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  2.2                         N*  0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  2.3                         y   0x00000000000011ce in C::func() at condbreak-multi-context.cc:39
  (*): Breakpoint condition is invalid at this location.

Here, uppercase 'N' denotes that the location is disabled because of
the invalid condition, as mentioned with a footnote in the legend of
the table.  Locations that are disabled by the user are still denoted
with lowercase 'n'.  Executing the code hits the breakpoints 1.2 and
2.3 as expected.

Defining a condition on an unconditional breakpoint gives the same
behavior above:

  (gdb) break func
  Breakpoint 1 at 0x11b6: func. (3 locations)
  (gdb) cond 1 a == 10
  warning: failed to validate condition at location 1.1, disabling:
    No symbol "a" in current context.
  warning: failed to validate condition at location 1.3, disabling:
    No symbol "a" in current context.
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
          stop only if a == 10
  1.1                         N*  0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  1.2                         y   0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  1.3                         N*  0x00000000000011ce in C::func() at condbreak-multi-context.cc:39
  (*): Breakpoint condition is invalid at this location.

Locations that are disabled because of a condition cannot be enabled
by the user:

  ...
  (gdb) enable 1.1
  Breakpoint 1's condition is invalid at location 1, cannot enable.

Resetting the condition enables the locations back:

  ...
  (gdb) cond 1
  Breakpoint 1's condition is now valid at location 1, enabling.
  Breakpoint 1's condition is now valid at location 3, enabling.
  Breakpoint 1 now unconditional.
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
  1.1                         y   0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  1.2                         y   0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  1.3                         y   0x00000000000011ce in C::func() at condbreak-multi-context.cc:39

If a location is disabled by the user, a condition can still be defined
but the location will remain disabled even if the condition is meaningful
for the disabled location:

  ...
  (gdb) disable 1.2
  (gdb) cond 1 a == 10
  warning: failed to validate condition at location 1.1, disabling:
    No symbol "a" in current context.
  warning: failed to validate condition at location 1.3, disabling:
    No symbol "a" in current context.
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
          stop only if a == 10
  1.1                         N*  0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  1.2                         n   0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  1.3                         N*  0x00000000000011ce in C::func() at condbreak-multi-context.cc:39
  (*): Breakpoint condition is invalid at this location.

The condition of a breakpoint can be changed.  Locations'
enable/disable states are updated accordingly.

  ...
  (gdb) cond 1 c == 30
  warning: failed to validate condition at location 1.1, disabling:
    No symbol "c" in current context.
  Breakpoint 1's condition is now valid at location 3, enabling.
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
          stop only if c == 30
  1.1                         N*  0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  1.2                         N*  0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  1.3                         y   0x00000000000011ce in C::func() at condbreak-multi-context.cc:39
  (*): Breakpoint condition is invalid at this location.

  (gdb) cond 1 b == 20
  Breakpoint 1's condition is now valid at location 1, enabling.
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
          stop only if b == 20
  1.1                         y   0x00000000000011b6 in Base::func() at condbreak-multi-context.cc:23
  1.2                         n   0x00000000000011c2 in A::func() at condbreak-multi-context.cc:31
  1.3                         y   0x00000000000011ce in C::func() at condbreak-multi-context.cc:39
  # Note that location 1.2 was disabled by the user previously.

If the condition expression is bad for all the locations, it will be
rejected.

  (gdb) cond 1 garbage
  No symbol "garbage" in current context.

For conditions that are invalid or valid for all the locations of a
breakpoint, the existing behavior is preserved.

Regression-tested on X86_64 Linux.

gdb/ChangeLog:
2020-10-27  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* breakpoint.h (class bp_location) <disabled_by_cond>: New field.
	* breakpoint.c (set_breakpoint_location_condition): New function.
	(set_breakpoint_condition): Disable a breakpoint location if parsing
	the condition string gives an error.
	(should_be_inserted): Update to consider the 'disabled_by_cond' field.
	(build_target_condition_list): Ditto.
	(build_target_command_list): Ditto.
	(build_bpstat_chain): Ditto.
	(print_one_breakpoint_location): Ditto.
	(print_one_breakpoint): Ditto.
	(breakpoint_1): Ditto.
	(bp_location::bp_location): Ditto.
	(locations_are_equal): Ditto.
	(update_breakpoint_locations): Ditto.
	(enable_disable_bp_num_loc): Ditto.
	(init_breakpoint_sal): Use set_breakpoint_location_condition.
	(find_condition_and_thread_for_sals): New static function.
	(create_breakpoint): Call find_condition_and_thread_for_sals.
	(location_to_sals): Call find_condition_and_thread_for_sals instead
	of find_condition_and_thread.

gdb/testsuite/ChangeLog:
2020-10-27  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.base/condbreak-multi-context.cc: New file.
	* gdb.base/condbreak-multi-context.exp: New file.

gdb/doc/ChangeLog:
2020-10-27  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.texinfo (Set Breaks): Document disabling of breakpoint
	locations for which the breakpoint condition is invalid.
This commit is contained in:
Tankut Baris Aktemur 2020-10-27 10:56:03 +01:00
parent afeee87bdc
commit b5fa468fef
8 changed files with 548 additions and 50 deletions

View file

@ -1,3 +1,26 @@
2020-10-27 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* breakpoint.h (class bp_location) <disabled_by_cond>: New field.
* breakpoint.c (set_breakpoint_location_condition): New function.
(set_breakpoint_condition): Disable a breakpoint location if parsing
the condition string gives an error.
(should_be_inserted): Update to consider the 'disabled_by_cond' field.
(build_target_condition_list): Ditto.
(build_target_command_list): Ditto.
(build_bpstat_chain): Ditto.
(print_one_breakpoint_location): Ditto.
(print_one_breakpoint): Ditto.
(breakpoint_1): Ditto.
(bp_location::bp_location): Ditto.
(locations_are_equal): Ditto.
(update_breakpoint_locations): Ditto.
(enable_disable_bp_num_loc): Ditto.
(init_breakpoint_sal): Use set_breakpoint_location_condition.
(find_condition_and_thread_for_sals): New static function.
(create_breakpoint): Call find_condition_and_thread_for_sals.
(location_to_sals): Call find_condition_and_thread_for_sals instead
of find_condition_and_thread.
2020-10-26 Tom de Vries <tdevries@suse.de>
* dwarf2/read.c (process_full_comp_unit): Call

View file

@ -830,6 +830,56 @@ get_first_locp_gte_addr (CORE_ADDR address)
return locp_found;
}
/* Parse COND_STRING in the context of LOC and set as the condition
expression of LOC. BP_NUM is the number of LOC's owner, LOC_NUM is
the number of LOC within its owner. In case of parsing error, mark
LOC as DISABLED_BY_COND. In case of success, unset DISABLED_BY_COND. */
static void
set_breakpoint_location_condition (const char *cond_string, bp_location *loc,
int bp_num, int loc_num)
{
bool has_junk = false;
try
{
expression_up new_exp = parse_exp_1 (&cond_string, loc->address,
block_for_pc (loc->address), 0);
if (*cond_string != 0)
has_junk = true;
else
{
loc->cond = std::move (new_exp);
if (loc->disabled_by_cond && loc->enabled)
printf_filtered (_("Breakpoint %d's condition is now valid at "
"location %d, enabling.\n"),
bp_num, loc_num);
loc->disabled_by_cond = false;
}
}
catch (const gdb_exception_error &e)
{
if (loc->enabled)
{
/* Warn if a user-enabled location is now becoming disabled-by-cond.
BP_NUM is 0 if the breakpoint is being defined for the first
time using the "break ... if ..." command, and non-zero if
already defined. */
if (bp_num != 0)
warning (_("failed to validate condition at location %d.%d, "
"disabling:\n %s"), bp_num, loc_num, e.what ());
else
warning (_("failed to validate condition at location %d, "
"disabling:\n %s"), loc_num, e.what ());
}
loc->disabled_by_cond = true;
}
if (has_junk)
error (_("Garbage '%s' follows condition"), cond_string);
}
void
set_breakpoint_condition (struct breakpoint *b, const char *exp,
int from_tty)
@ -843,9 +893,16 @@ set_breakpoint_condition (struct breakpoint *b, const char *exp,
static_cast<watchpoint *> (b)->cond_exp.reset ();
else
{
int loc_num = 1;
for (bp_location *loc = b->loc; loc != nullptr; loc = loc->next)
{
loc->cond.reset ();
if (loc->disabled_by_cond && loc->enabled)
printf_filtered (_("Breakpoint %d's condition is now valid at "
"location %d, enabling.\n"),
b->number, loc_num);
loc->disabled_by_cond = false;
loc_num++;
/* No need to free the condition agent expression
bytecode (if we have one). We will handle this
@ -873,29 +930,37 @@ set_breakpoint_condition (struct breakpoint *b, const char *exp,
{
/* Parse and set condition expressions. We make two passes.
In the first, we parse the condition string to see if it
is valid in all locations. If so, the condition would be
accepted. So we go ahead and set the locations'
conditions. In case a failing case is found, we throw
is valid in at least one location. If so, the condition
would be accepted. So we go ahead and set the locations'
conditions. In case no valid case is found, we throw
the error and the condition string will be rejected.
This two-pass approach is taken to avoid setting the
state of locations in case of a reject. */
for (bp_location *loc = b->loc; loc != nullptr; loc = loc->next)
{
const char *arg = exp;
parse_exp_1 (&arg, loc->address,
block_for_pc (loc->address), 0);
if (*arg != 0)
error (_("Junk at end of expression"));
try
{
const char *arg = exp;
parse_exp_1 (&arg, loc->address,
block_for_pc (loc->address), 0);
if (*arg != 0)
error (_("Junk at end of expression"));
break;
}
catch (const gdb_exception_error &e)
{
/* Condition string is invalid. If this happens to
be the last loc, abandon. */
if (loc->next == nullptr)
throw;
}
}
/* If we reach here, the condition is valid at all locations. */
for (bp_location *loc = b->loc; loc != nullptr; loc = loc->next)
{
const char *arg = exp;
loc->cond =
parse_exp_1 (&arg, loc->address,
block_for_pc (loc->address), 0);
}
/* If we reach here, the condition is valid at some locations. */
int loc_num = 1;
for (bp_location *loc = b->loc; loc != nullptr;
loc = loc->next, loc_num++)
set_breakpoint_location_condition (exp, loc, b->number, loc_num);
}
/* We know that the new condition parsed successfully. The
@ -2010,7 +2075,8 @@ should_be_inserted (struct bp_location *bl)
if (bl->owner->disposition == disp_del_at_next_stop)
return 0;
if (!bl->enabled || bl->shlib_disabled || bl->duplicate)
if (!bl->enabled || bl->disabled_by_cond
|| bl->shlib_disabled || bl->duplicate)
return 0;
if (user_breakpoint_p (bl->owner) && bl->pspace->executing_startup)
@ -2205,7 +2271,8 @@ build_target_condition_list (struct bp_location *bl)
&& is_breakpoint (loc->owner)
&& loc->pspace->num == bl->pspace->num
&& loc->owner->enable_state == bp_enabled
&& loc->enabled)
&& loc->enabled
&& !loc->disabled_by_cond)
{
/* Add the condition to the vector. This will be used later
to send the conditions to the target. */
@ -2395,7 +2462,8 @@ build_target_command_list (struct bp_location *bl)
&& is_breakpoint (loc->owner)
&& loc->pspace->num == bl->pspace->num
&& loc->owner->enable_state == bp_enabled
&& loc->enabled)
&& loc->enabled
&& !loc->disabled_by_cond)
{
/* Add the command to the vector. This will be used later
to send the commands to the target. */
@ -5278,7 +5346,7 @@ build_bpstat_chain (const address_space *aspace, CORE_ADDR bp_addr,
if (b->type == bp_hardware_watchpoint && bl != b->loc)
break;
if (!bl->enabled || bl->shlib_disabled)
if (!bl->enabled || bl->disabled_by_cond || bl->shlib_disabled)
continue;
if (!bpstat_check_location (bl, aspace, bp_addr, ws))
@ -5987,7 +6055,8 @@ print_one_breakpoint_location (struct breakpoint *b,
breakpoints with single disabled location. */
if (loc == NULL
&& (b->loc != NULL
&& (b->loc->next != NULL || !b->loc->enabled)))
&& (b->loc->next != NULL
|| !b->loc->enabled || b->loc->disabled_by_cond)))
header_of_multiple = 1;
if (loc == NULL)
loc = b->loc;
@ -6018,7 +6087,8 @@ print_one_breakpoint_location (struct breakpoint *b,
/* 4 */
annotate_field (3);
if (part_of_multiple)
uiout->field_string ("enabled", loc->enabled ? "y" : "n");
uiout->field_string ("enabled", (loc->disabled_by_cond ? "N*"
: (loc->enabled ? "y" : "n")));
else
uiout->field_fmt ("enabled", "%c", bpenables[(int) b->enable_state]);
@ -6318,7 +6388,9 @@ print_one_breakpoint (struct breakpoint *b,
&& (!is_catchpoint (b) || is_exception_catchpoint (b)
|| is_ada_exception_catchpoint (b))
&& (allflag
|| (b->loc && (b->loc->next || !b->loc->enabled))))
|| (b->loc && (b->loc->next
|| !b->loc->enabled
|| b->loc->disabled_by_cond))))
{
gdb::optional<ui_out_emit_list> locations_list;
@ -6412,6 +6484,7 @@ breakpoint_1 (const char *bp_num_list, bool show_internal,
int print_address_bits = 0;
int print_type_col_width = 14;
struct ui_out *uiout = current_uiout;
bool has_disabled_by_cond_location = false;
get_user_print_options (&opts);
@ -6512,7 +6585,12 @@ breakpoint_1 (const char *bp_num_list, bool show_internal,
/* We only print out user settable breakpoints unless the
show_internal is set. */
if (show_internal || user_breakpoint_p (b))
print_one_breakpoint (b, &last_loc, show_internal);
{
print_one_breakpoint (b, &last_loc, show_internal);
for (bp_location *loc = b->loc; loc != NULL; loc = loc->next)
if (loc->disabled_by_cond)
has_disabled_by_cond_location = true;
}
}
}
@ -6533,6 +6611,10 @@ breakpoint_1 (const char *bp_num_list, bool show_internal,
{
if (last_loc && !server_command)
set_next_address (last_loc->gdbarch, last_loc->address);
if (has_disabled_by_cond_location)
uiout->message (_("(*): Breakpoint condition is invalid at this "
"location.\n"));
}
/* FIXME? Should this be moved up so that it is only called when
@ -6960,6 +7042,7 @@ bp_location::bp_location (breakpoint *owner, bp_loc_type type)
this->cond_bytecode = NULL;
this->shlib_disabled = 0;
this->enabled = 1;
this->disabled_by_cond = false;
this->loc_type = type;
@ -8832,15 +8915,9 @@ init_breakpoint_sal (struct breakpoint *b, struct gdbarch *gdbarch,
loc->inserted = 1;
}
if (b->cond_string)
{
const char *arg = b->cond_string;
loc->cond = parse_exp_1 (&arg, loc->address,
block_for_pc (loc->address), 0);
if (*arg)
error (_("Garbage '%s' follows condition"), arg);
}
/* Do not set breakpoint locations conditions yet. As locations
are inserted, they get sorted based on their addresses. Let
the list stabilize to have reliable location numbers. */
/* Dynamic printf requires and uses additional arguments on the
command line, otherwise it's an error. */
@ -8855,6 +8932,19 @@ init_breakpoint_sal (struct breakpoint *b, struct gdbarch *gdbarch,
error (_("Garbage '%s' at end of command"), b->extra_string);
}
/* The order of the locations is now stable. Set the location
condition using the location's number. */
int loc_num = 1;
for (bp_location *loc = b->loc; loc != nullptr; loc = loc->next)
{
if (b->cond_string != nullptr)
set_breakpoint_location_condition (b->cond_string, loc, b->number,
loc_num);
++loc_num;
}
b->display_canonical = display_canonical;
if (location != NULL)
b->location = std::move (location);
@ -9143,6 +9233,50 @@ find_condition_and_thread (const char *tok, CORE_ADDR pc,
}
}
/* Call 'find_condition_and_thread' for each sal in SALS until a parse
succeeds. The parsed values are written to COND_STRING, THREAD,
TASK, and REST. See the comment of 'find_condition_and_thread'
for the description of these parameters and INPUT. */
static void
find_condition_and_thread_for_sals (const std::vector<symtab_and_line> &sals,
const char *input, char **cond_string,
int *thread, int *task, char **rest)
{
int num_failures = 0;
for (auto &sal : sals)
{
char *cond = nullptr;
int thread_id = 0;
int task_id = 0;
char *remaining = nullptr;
/* Here we want to parse 'arg' to separate condition from thread
number. But because parsing happens in a context and the
contexts of sals might be different, try each until there is
success. Finding one successful parse is sufficient for our
goal. When setting the breakpoint we'll re-parse the
condition in the context of each sal. */
try
{
find_condition_and_thread (input, sal.pc, &cond, &thread_id,
&task_id, &remaining);
*cond_string = cond;
*thread = thread_id;
*task = task_id;
*rest = remaining;
break;
}
catch (const gdb_exception_error &e)
{
num_failures++;
/* If no sal remains, do not continue. */
if (num_failures == sals.size ())
throw;
}
}
}
/* Decode a static tracepoint marker spec. */
static std::vector<symtab_and_line>
@ -9306,13 +9440,8 @@ create_breakpoint (struct gdbarch *gdbarch,
const linespec_sals &lsal = canonical.lsals[0];
/* Here we only parse 'arg' to separate condition
from thread number, so parsing in context of first
sal is OK. When setting the breakpoint we'll
re-parse it in context of each sal. */
find_condition_and_thread (extra_string, lsal.sals[0].pc,
&cond, &thread, &task, &rest);
find_condition_and_thread_for_sals (lsal.sals, extra_string,
&cond, &thread, &task, &rest);
cond_string_copy.reset (cond);
extra_string_copy.reset (rest);
}
@ -13414,6 +13543,9 @@ locations_are_equal (struct bp_location *a, struct bp_location *b)
if (a->enabled != b->enabled)
return 0;
if (a->disabled_by_cond != b->disabled_by_cond)
return 0;
a = a->next;
b = b->next;
}
@ -13521,10 +13653,7 @@ update_breakpoint_locations (struct breakpoint *b,
}
catch (const gdb_exception_error &e)
{
warning (_("failed to reevaluate condition "
"for breakpoint %d: %s"),
b->number, e.what ());
new_loc->enabled = 0;
new_loc->disabled_by_cond = true;
}
}
@ -13549,7 +13678,7 @@ update_breakpoint_locations (struct breakpoint *b,
for (; e; e = e->next)
{
if (!e->enabled && e->function_name)
if ((!e->enabled || e->disabled_by_cond) && e->function_name)
{
struct bp_location *l = b->loc;
if (have_ambiguous_names)
@ -13565,7 +13694,8 @@ update_breakpoint_locations (struct breakpoint *b,
enough. */
if (breakpoint_locations_match (e, l, true))
{
l->enabled = 0;
l->enabled = e->enabled;
l->disabled_by_cond = e->disabled_by_cond;
break;
}
}
@ -13576,7 +13706,8 @@ update_breakpoint_locations (struct breakpoint *b,
if (l->function_name
&& strcmp (e->function_name, l->function_name) == 0)
{
l->enabled = 0;
l->enabled = e->enabled;
l->disabled_by_cond = e->disabled_by_cond;
break;
}
}
@ -13650,9 +13781,9 @@ location_to_sals (struct breakpoint *b, struct event_location *location,
char *cond_string, *extra_string;
int thread, task;
find_condition_and_thread (b->extra_string, sals[0].pc,
&cond_string, &thread, &task,
&extra_string);
find_condition_and_thread_for_sals (sals, b->extra_string,
&cond_string, &thread,
&task, &extra_string);
gdb_assert (b->cond_string == NULL);
if (cond_string)
b->cond_string = cond_string;
@ -14137,6 +14268,10 @@ enable_disable_bp_num_loc (int bp_num, int loc_num, bool enable)
struct bp_location *loc = find_location_by_number (bp_num, loc_num);
if (loc != NULL)
{
if (loc->disabled_by_cond && enable)
error (_("Breakpoint %d's condition is invalid at location %d, "
"cannot enable."), bp_num, loc_num);
if (loc->enabled != enable)
{
loc->enabled = enable;

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@ -387,6 +387,12 @@ public:
/* Is this particular location enabled. */
bool enabled = false;
/* Is this particular location disabled because the condition
expression is invalid at this location. For a location to be
reported as enabled, the ENABLED field above has to be true *and*
the DISABLED_BY_COND field has to be false. */
bool disabled_by_cond = false;
/* True if this breakpoint is now inserted. */
bool inserted = false;

View file

@ -1,3 +1,8 @@
2020-10-27 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* gdb.texinfo (Set Breaks): Document disabling of breakpoint
locations for which the breakpoint condition is invalid.
2020-10-06 Michael Forney <mforney@mforney.org>
* Makefile.in (HAVE_NATIVE_GCORE_HOST): Add for gcore.1

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@ -4278,6 +4278,46 @@ value is nonzero---that is, if @var{cond} evaluates as true.
above (or no argument) specifying where to break. @xref{Conditions,
,Break Conditions}, for more information on breakpoint conditions.
The breakpoint may be mapped to multiple locations. If the breakpoint
condition @var{cond} is invalid at some but not all of the locations,
the locations for which the condition is invalid are disabled. For
example, @value{GDBN} reports below that two of the three locations
are disabled.
@smallexample
(@value{GDBP}) break func if a == 10
warning: failed to validate condition at location 0x11ce, disabling:
No symbol "a" in current context.
warning: failed to validate condition at location 0x11b6, disabling:
No symbol "a" in current context.
Breakpoint 1 at 0x11b6: func. (3 locations)
@end smallexample
Locations that are disabled because of the condition are denoted by an
uppercase @code{N} in the output of the @code{info breakpoints}
command:
@smallexample
(@value{GDBP}) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y <MULTIPLE>
stop only if a == 10
1.1 N* 0x00000000000011b6 in ...
1.2 y 0x00000000000011c2 in ...
1.3 N* 0x00000000000011ce in ...
(*): Breakpoint condition is invalid at this location.
@end smallexample
If the breakpoint condition @var{cond} is invalid in the context of
@emph{all} the locations of the breakpoint, @value{GDBN} refuses to
define the breakpoint. For example, if variable @code{foo} is an
undefined variable:
@smallexample
(@value{GDBP}) break func if foo
No symbol "foo" in current context.
@end smallexample
@kindex tbreak
@item tbreak @var{args}
Set a breakpoint enabled only for one stop. The @var{args} are the

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@ -1,3 +1,8 @@
2020-10-27 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* gdb.base/condbreak-multi-context.cc: New file.
* gdb.base/condbreak-multi-context.exp: New file.
2020-10-26 Tom Tromey <tom@tromey.com>
* lib/mi-support.exp (default_mi_gdb_start): Call

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@ -0,0 +1,54 @@
/* This testcase is part of GDB, the GNU debugger.
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 <http://www.gnu.org/licenses/>. */
class Base
{
public:
int b = 20;
void func () {}
};
class A : public Base
{
public:
int a = 10;
void func () {}
};
class C : public Base
{
public:
int c = 30;
void func () {}
};
int
main ()
{
Base bobj;
A aobj;
C cobj;
aobj.func ();
bobj.func ();
cobj.func ();
return 0;
}

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@ -0,0 +1,230 @@
# 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 <http://www.gnu.org/licenses/>.
# Test defining a conditional breakpoint that applies to multiple
# locations with different contexts (e.g. different set of local vars).
standard_testfile .cc
if {[prepare_for_testing "failed to prepare" ${binfile} ${srcfile}]} {
return
}
set warning "warning: failed to validate condition"
set fill "\[^\r\n\]*"
# Check that breakpoints are as expected.
proc test_info_break {suffix} {
global bpnum1 bpnum2 fill
set bp_hit_info "${fill}(\r\n${fill}breakpoint already hit 1 time)?"
gdb_test "info break ${bpnum1} ${bpnum2}" \
[multi_line \
"Num${fill}" \
"${bpnum1}${fill}breakpoint${fill}keep y${fill}MULTIPLE${fill}" \
"${fill}stop only if a == 10${bp_hit_info}" \
"${bpnum1}.1${fill}N\\*${fill}Base::func${fill}" \
"${bpnum1}.2${fill}y${fill}A::func${fill}" \
"${bpnum1}.3${fill}N\\*${fill}C::func${fill}" \
"${bpnum2}${fill}breakpoint${fill}keep y${fill}MULTIPLE${fill}" \
"${fill}stop only if c == 30${bp_hit_info}" \
"${bpnum2}.1${fill}N\\*${fill}Base::func${fill}" \
"${bpnum2}.2${fill}N\\*${fill}A::func${fill}" \
"${bpnum2}.3${fill}y${fill}C::func${fill}" \
"\\(\\*\\): Breakpoint condition is invalid at this location."] \
"info break $suffix"
}
# Scenario 1: Define breakpoints conditionally, using the "break N if
# cond" syntax. Run the program, check that we hit those locations
# only.
with_test_prefix "scenario 1" {
# Define the conditional breakpoints.
gdb_test "break func if a == 10" \
[multi_line \
"${warning} at location 1, disabling:" \
" No symbol \"a\" in current context." \
"${warning} at location 3, disabling:" \
" No symbol \"a\" in current context." \
"Breakpoint $decimal at $fill .3 locations."] \
"define bp with condition a == 10"
set bpnum1 [get_integer_valueof "\$bpnum" 0 "get bpnum1"]
gdb_test "break func if c == 30" \
[multi_line \
".*${warning} at location 1, disabling:" \
" No symbol \"c\" in current context." \
".*${warning} at location 2, disabling:" \
" No symbol \"c\" in current context." \
".*Breakpoint $decimal at $fill .3 locations."] \
"define bp with condition c == 30"
set bpnum2 [get_integer_valueof "\$bpnum" 0 "get bpnum2"]
test_info_break 1
# Do not use runto_main, it deletes all breakpoints.
gdb_run_cmd
# Check our conditional breakpoints.
gdb_test "" ".*Breakpoint \[0-9\]+, A::func .*" \
"run until A::func"
gdb_test "print a" " = 10"
gdb_test "continue" "Continuing.*Breakpoint \[0-9\]+, C::func .*" \
"run until C::func"
gdb_test "print c" " = 30"
# No more hits!
gdb_continue_to_end
test_info_break 2
}
# Start GDB with two breakpoints and define the conditions separately.
proc setup_bps {} {
global srcfile binfile srcfile2
global bpnum1 bpnum2 bp_location warning
clean_restart ${binfile}
# Define the breakpoints.
gdb_breakpoint "func"
set bpnum1 [get_integer_valueof "\$bpnum" 0 "get bpnum1"]
gdb_breakpoint "func"
set bpnum2 [get_integer_valueof "\$bpnum" 0 "get bpnum2"]
# Defining a condition on 'a' disables 2 locations.
gdb_test "cond $bpnum1 a == 10" \
[multi_line \
"$warning at location ${bpnum1}.1, disabling:" \
" No symbol \"a\" in current context." \
"$warning at location ${bpnum1}.3, disabling:" \
" No symbol \"a\" in current context."]
# Defining a condition on 'c' disables 2 locations.
gdb_test "cond $bpnum2 c == 30" \
[multi_line \
"$warning at location ${bpnum2}.1, disabling:" \
" No symbol \"c\" in current context." \
"$warning at location ${bpnum2}.2, disabling:" \
" No symbol \"c\" in current context."]
}
# Scenario 2: Define breakpoints unconditionally, and then define
# conditions using the "cond N <cond>" syntax. Expect that the
# locations where <cond> is not evaluatable are disabled. Run the
# program, check that we hit the enabled locations only.
with_test_prefix "scenario 2" {
setup_bps
test_info_break 1
# Do not use runto_main, it deletes all breakpoints.
gdb_run_cmd
# Check that we hit enabled locations only.
gdb_test "" ".*Breakpoint \[0-9\]+, A::func .*" \
"run until A::func"
gdb_test "print a" " = 10"
gdb_test "continue" "Continuing.*Breakpoint \[0-9\]+, C::func .*" \
"run until C::func"
gdb_test "print c" " = 30"
# No more hits!
gdb_continue_to_end
test_info_break 2
}
# Test the breakpoint location enabled states.
proc check_bp_locations {bpnum states msg} {
global fill
set expected ".*${bpnum}.1${fill} [lindex $states 0] ${fill}\r\n"
append expected "${bpnum}.2${fill} [lindex $states 1] ${fill}\r\n"
append expected "${bpnum}.3${fill} [lindex $states 2] ${fill}"
if {[lsearch $states N*] >= 0} {
append expected "\r\n\\(\\*\\): Breakpoint condition is invalid at this location."
}
gdb_test "info break $bpnum" $expected "check bp $bpnum $msg"
}
# Scenario 3: Apply misc. checks on the already-defined breakpoints.
with_test_prefix "scenario 3" {
setup_bps
gdb_test "cond $bpnum1 c == 30" \
[multi_line \
"${warning} at location ${bpnum1}.1, disabling:" \
" No symbol \"c\" in current context." \
"${warning} at location ${bpnum1}.2, disabling:" \
" No symbol \"c\" in current context." \
"Breakpoint ${bpnum1}'s condition is now valid at location 3, enabling."] \
"change the condition of bp 1"
check_bp_locations $bpnum1 {N* N* y} "after changing the condition"
gdb_test "cond $bpnum1" \
[multi_line \
"Breakpoint ${bpnum1}'s condition is now valid at location 1, enabling." \
"Breakpoint ${bpnum1}'s condition is now valid at location 2, enabling." \
"Breakpoint ${bpnum1} now unconditional."] \
"reset the condition of bp 1"
check_bp_locations $bpnum1 {y y y} "after resetting the condition"
gdb_test_no_output "disable ${bpnum2}.2"
check_bp_locations $bpnum2 {N* N* y} "after disabling loc 2"
gdb_test "cond $bpnum2" ".*" "reset the condition of bp 2"
check_bp_locations $bpnum2 {y n y} "loc 2 should remain disabled"
gdb_test_no_output "disable ${bpnum2}.3"
check_bp_locations $bpnum2 {y n n} "after disabling loc 3"
gdb_test "cond $bpnum2 c == 30" \
[multi_line \
"${warning} at location ${bpnum2}.1, disabling:" \
" No symbol \"c\" in current context."] \
"re-define a condition"
check_bp_locations $bpnum2 {N* N* n} "loc 3 should remain disabled"
gdb_test "enable ${bpnum2}.1" \
"Breakpoint ${bpnum2}'s condition is invalid at location 1, cannot enable." \
"reject enabling a location that is disabled-by-cond"
check_bp_locations $bpnum2 {N* N* n} "after enable attempt"
gdb_test "cond $bpnum2 garbage" \
"No symbol \"garbage\" in current context." \
"reject condition if bad for all locations"
gdb_test_no_output "delete $bpnum1"
# Do not use runto_main, it deletes all breakpoints.
gdb_breakpoint "main"
gdb_run_cmd
gdb_test "" ".*reakpoint .*, main .*${srcfile}.*" "start"
# The second BP's locations are all disabled. No more hits!
gdb_continue_to_end
}