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* breakpoint.c (fetch_watchpoint_value): New function.

Browse Source 
(update_watchpoint): Set and clear val_valid.  Use
	fetch_watchpoint_value.  Handle unreadable values on the
	value chain.  Correct check for user-requested array watchpoints.
	(breakpoint_init_inferior): Clear val_valid.
	(watchpoint_value_print): New function.
	(print_it_typical): Use it.  Do not free or clear old_val.  Print
	watchpoints even if old_val == NULL.
	(watchpoint_check): Use fetch_watchpoint_value.  Check for values
	becoming readable or unreadable.
	(watch_command_1): Use fetch_watchpoint_value.  Set val_valid.
	(do_enable_watchpoint): Likewise.
	* breakpoint.h (struct breakpoint): Update comment for val.  Add
	val_valid.
	* NEWS: Mention watchpoints on inaccessible memory.

	* gdb.base/watchpoint.c (global_ptr, func4): New.
	(main): Call func4.
	* gdb.base/watchpoint.exp: Call test_inaccessible_watchpoint.
	(test_inaccessible_watchpoint): New.

	* gdb.texinfo (Set Watchpoints): Mention watchpoints on
	unreadable memory.  Delete obsolete SPARClite reference.
This commit is contained in:
Daniel Jacobowitz
2008-03-03 13:24:12 +00:00
parent 35d60fe406
commit fa4727a64f
9 changed files with 213 additions and 74 deletions
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188
gdb/breakpoint.c
View File

@@ -55,6 +55,7 @@
#include "memattr.h"
#include "ada-lang.h"
#include "top.h"
#include "wrapper.h"
#include "gdb-events.h"
#include "mi/mi-common.h"
@@ -826,7 +827,65 @@ is_hardware_watchpoint (struct breakpoint *bpt)
|| bpt->type == bp_access_watchpoint);
}
/* Assuming that B is a hardware breakpoint:
/* Find the current value of a watchpoint on EXP. Return the value in
*VALP and *RESULTP and the chain of intermediate and final values
in *VAL_CHAIN. RESULTP and VAL_CHAIN may be NULL if the caller does
not need them.
If an error occurs while evaluating the expression, *RESULTP will
be set to NULL. *RESULTP may be a lazy value, if the result could
not be read from memory. It is used to determine whether a value
is user-specified (we should watch the whole value) or intermediate
(we should watch only the bit used to locate the final value).
If the final value, or any intermediate value, could not be read
from memory, *VALP will be set to NULL. *VAL_CHAIN will still be
set to any referenced values. *VALP will never be a lazy value.
This is the value which we store in struct breakpoint.
If VAL_CHAIN is non-NULL, *VAL_CHAIN will be released from the
value chain. The caller must free the values individually. If
VAL_CHAIN is NULL, all generated values will be left on the value
chain. */
static void
fetch_watchpoint_value (struct expression *exp, struct value **valp,
struct value **resultp, struct value **val_chain)
{
struct value *mark, *new_mark, *result;
*valp = NULL;
if (resultp)
*resultp = NULL;
if (val_chain)
*val_chain = NULL;
/* Evaluate the expression. */
mark = value_mark ();
result = NULL;
gdb_evaluate_expression (exp, &result);
new_mark = value_mark ();
if (mark == new_mark)
return;
if (resultp)
*resultp = result;
/* Make sure it's not lazy, so that after the target stops again we
have a non-lazy previous value to compare with. */
if (result != NULL
&& (!value_lazy (result) || gdb_value_fetch_lazy (result)))
*valp = result;
if (val_chain)
{
/* Return the chain of intermediate values. We use this to
decide which addresses to watch. */
*val_chain = new_mark;
value_release_to_mark (mark);
}
}
/* Assuming that B is a hardware watchpoint:
- Reparse watchpoint expression, is REPARSE is non-zero
- Evaluate expression and store the result in B->val
- Update the list of values that must be watched in B->loc.
@@ -837,7 +896,6 @@ static void
update_watchpoint (struct breakpoint *b, int reparse)
{
int within_current_scope;
struct value *mark = value_mark ();
struct frame_id saved_frame_id;
struct bp_location *loc;
bpstat bs;
@@ -889,9 +947,9 @@ update_watchpoint (struct breakpoint *b, int reparse)
to the user when the old value and the new value may actually
be completely different objects. */
value_free (b->val);
b->val = NULL;
b->val = NULL;
b->val_valid = 0;
}
/* If we failed to parse the expression, for example because
it refers to a global variable in a not-yet-loaded shared library,
@@ -900,43 +958,37 @@ update_watchpoint (struct breakpoint *b, int reparse)
is different from out-of-scope watchpoint. */
if (within_current_scope && b->exp)
{
struct value *v, *next;
struct value *val_chain, *v, *result, *next;
/* Evaluate the expression and make sure it's not lazy, so that
after target stops again, we have a non-lazy previous value
to compare with. Also, making the value non-lazy will fetch
intermediate values as needed, which we use to decide which
addresses to watch.
fetch_watchpoint_value (b->exp, &v, &result, &val_chain);
The value returned by evaluate_expression is stored in b->val.
In addition, we look at all values which were created
during evaluation, and set watchoints at addresses as needed.
Those values are explicitly deleted here. */
v = evaluate_expression (b->exp);
/* Avoid setting b->val if it's already set. The meaning of
b->val is 'the last value' user saw, and we should update
it only if we reported that last value to user. As it
happens, the code that reports it updates b->val directly. */
if (b->val == NULL)
b->val = v;
value_contents (v);
value_release_to_mark (mark);
if (!b->val_valid)
{
b->val = v;
b->val_valid = 1;
}
/* Look at each value on the value chain. */
for (; v; v = next)
for (v = val_chain; v; v = next)
{
/* If it's a memory location, and GDB actually needed
its contents to evaluate the expression, then we
must watch it. */
must watch it. If the first value returned is
still lazy, that means an error occurred reading it;
watch it anyway in case it becomes readable. */
if (VALUE_LVAL (v) == lval_memory
&& ! value_lazy (v))
&& (v == val_chain || ! value_lazy (v)))
{
struct type *vtype = check_typedef (value_type (v));
/* We only watch structs and arrays if user asked
for it explicitly, never if they just happen to
appear in the middle of some value chain. */
if (v == b->val
if (v == result
|| (TYPE_CODE (vtype) != TYPE_CODE_STRUCT
&& TYPE_CODE (vtype) != TYPE_CODE_ARRAY))
{
@@ -1681,6 +1733,7 @@ breakpoint_init_inferior (enum inf_context context)
if (b->val)
value_free (b->val);
b->val = NULL;
b->val_valid = 0;
}
break;
default:
@@ -2103,6 +2156,17 @@ top:
do_cleanups (old_chain);
}
/* Print out the (old or new) value associated with a watchpoint. */
static void
watchpoint_value_print (struct value *val, struct ui_file *stream)
{
if (val == NULL)
fprintf_unfiltered (stream, _("<unreadable>"));
else
value_print (val, stream, 0, Val_pretty_default);
}
/* This is the normal print function for a bpstat. In the future,
much of this logic could (should?) be moved to bpstat_stop_status,
by having it set different print_it values.
@@ -2221,26 +2285,21 @@ print_it_typical (bpstat bs)
case bp_watchpoint:
case bp_hardware_watchpoint:
if (bs->old_val != NULL)
{
annotate_watchpoint (b->number);
if (ui_out_is_mi_like_p (uiout))
ui_out_field_string
(uiout, "reason",
async_reason_lookup (EXEC_ASYNC_WATCHPOINT_TRIGGER));
mention (b);
ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "value");
ui_out_text (uiout, "\nOld value = ");
value_print (bs->old_val, stb->stream, 0, Val_pretty_default);
ui_out_field_stream (uiout, "old", stb);
ui_out_text (uiout, "\nNew value = ");
value_print (b->val, stb->stream, 0, Val_pretty_default);
ui_out_field_stream (uiout, "new", stb);
do_cleanups (ui_out_chain);
ui_out_text (uiout, "\n");
value_free (bs->old_val);
bs->old_val = NULL;
}
annotate_watchpoint (b->number);
if (ui_out_is_mi_like_p (uiout))
ui_out_field_string
(uiout, "reason",
async_reason_lookup (EXEC_ASYNC_WATCHPOINT_TRIGGER));
mention (b);
ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "value");
ui_out_text (uiout, "\nOld value = ");
watchpoint_value_print (bs->old_val, stb->stream);
ui_out_field_stream (uiout, "old", stb);
ui_out_text (uiout, "\nNew value = ");
watchpoint_value_print (b->val, stb->stream);
ui_out_field_stream (uiout, "new", stb);
do_cleanups (ui_out_chain);
ui_out_text (uiout, "\n");
/* More than one watchpoint may have been triggered. */
return PRINT_UNKNOWN;
break;
@@ -2253,7 +2312,7 @@ print_it_typical (bpstat bs)
mention (b);
ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "value");
ui_out_text (uiout, "\nValue = ");
value_print (b->val, stb->stream, 0, Val_pretty_default);
watchpoint_value_print (b->val, stb->stream);
ui_out_field_stream (uiout, "value", stb);
do_cleanups (ui_out_chain);
ui_out_text (uiout, "\n");
@@ -2261,7 +2320,7 @@ print_it_typical (bpstat bs)
break;
case bp_access_watchpoint:
if (bs->old_val != NULL)
if (bs->old_val != NULL)
{
annotate_watchpoint (b->number);
if (ui_out_is_mi_like_p (uiout))
@@ -2271,10 +2330,8 @@ print_it_typical (bpstat bs)
mention (b);
ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "value");
ui_out_text (uiout, "\nOld value = ");
value_print (bs->old_val, stb->stream, 0, Val_pretty_default);
watchpoint_value_print (bs->old_val, stb->stream);
ui_out_field_stream (uiout, "old", stb);
value_free (bs->old_val);
bs->old_val = NULL;
ui_out_text (uiout, "\nNew value = ");
}
else
@@ -2287,7 +2344,7 @@ print_it_typical (bpstat bs)
ui_out_chain = make_cleanup_ui_out_tuple_begin_end (uiout, "value");
ui_out_text (uiout, "\nValue = ");
}
value_print (b->val, stb->stream, 0,Val_pretty_default);
watchpoint_value_print (b->val, stb->stream);
ui_out_field_stream (uiout, "new", stb);
do_cleanups (ui_out_chain);
ui_out_text (uiout, "\n");
@@ -2574,13 +2631,20 @@ watchpoint_check (void *p)
we might be in the middle of evaluating a function call. */
struct value *mark = value_mark ();
struct value *new_val = evaluate_expression (b->exp);
if (!value_equal (b->val, new_val))
struct value *new_val;
fetch_watchpoint_value (b->exp, &new_val, NULL, NULL);
if ((b->val != NULL) != (new_val != NULL)
|| (b->val != NULL && !value_equal (b->val, new_val)))
{
release_value (new_val);
value_free_to_mark (mark);
if (new_val != NULL)
{
release_value (new_val);
value_free_to_mark (mark);
}
bs->old_val = b->val;
b->val = new_val;
b->val_valid = 1;
/* We will stop here */
return WP_VALUE_CHANGED;
}
@@ -5746,10 +5810,9 @@ watch_command_1 (char *arg, int accessflag, int from_tty)
exp_end = arg;
exp_valid_block = innermost_block;
mark = value_mark ();
val = evaluate_expression (exp);
release_value (val);
if (value_lazy (val))
value_fetch_lazy (val);
fetch_watchpoint_value (exp, &val, NULL, NULL);
if (val != NULL)
release_value (val);
tok = arg;
while (*tok == ' ' || *tok == '\t')
@@ -5838,6 +5901,7 @@ watch_command_1 (char *arg, int accessflag, int from_tty)
b->exp_valid_block = exp_valid_block;
b->exp_string = savestring (exp_start, exp_end - exp_start);
b->val = val;
b->val_valid = 1;
b->loc->cond = cond;
if (cond_start)
b->cond_string = savestring (cond_start, cond_end - cond_start);
@@ -7721,11 +7785,11 @@ is valid is not currently in scope.\n"), bpt->number);
if (bpt->val)
value_free (bpt->val);
mark = value_mark ();
bpt->val = evaluate_expression (bpt->exp);
release_value (bpt->val);
if (value_lazy (bpt->val))
value_fetch_lazy (bpt->val);
fetch_watchpoint_value (bpt->exp, &bpt->val, NULL, NULL);
if (bpt->val)
release_value (bpt->val);
bpt->val_valid = 1;
if (bpt->type == bp_hardware_watchpoint ||
bpt->type == bp_read_watchpoint ||
bpt->type == bp_access_watchpoint)