2008-07-10 Jan Kratochvil <jan.kratochvil@redhat.com>
* breakpoint.c (fetch_watchpoint_value): New comment on unreachable
values.
(watch_command_1): New variable VAL_CHAIN. Refuse constant watchpoints.
* gdbtypes.h (TYPE_CODE_FUNC): New comment regarding pointers to it.
2008-07-10 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.texinfo (Set Watchpoints): Document constant value watchpoints.
2008-07-10 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.base/watchpoint.exp: Call TEST_CONSTANT_WATCHPOINT.
(test_constant_watchpoint): New function.
(test_inaccessible_watchpoint): Cleanup (delete) the watchpoint.
Test also a double-indirection watchpoint.
gdb.base/watchpoint.c (global_ptr_ptr): New variable.
(func4): New testing code for GLOBAL_PTR_PTR.
Index: gdb-6.8.50.20090209/gdb/breakpoint.c
===================================================================
--- gdb-6.8.50.20090209.orig/gdb/breakpoint.c 2009-02-09 15:39:01.000000000 +0100
+++ gdb-6.8.50.20090209/gdb/breakpoint.c 2009-02-09 16:04:10.000000000 +0100
@@ -769,7 +769,15 @@ is_hardware_watchpoint (struct breakpoin
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. */
+ chain.
+
+ Inferior unreachable values return:
+ Inferior `int *intp = NULL;' with `watch *intp':
+ *VALP is NULL, *RESULTP contains lazy LVAL_MEMORY address 0, *VAL_CHAIN
+ contains the *RESULTP element and also INTP as LVAL_MEMORY.
+ Inferior `int **intpp = NULL;' with `watch **intpp':
+ *VALP is NULL, *RESULTP is NULL, *VAL_CHAIN contains lazy LVAL_MEMORY
+ address 0 and also INTPP as LVAL_MEMORY. */
static void
fetch_watchpoint_value (struct expression *exp, struct value **valp,
@@ -5862,7 +5870,7 @@ watch_command_1 (char *arg, int accessfl
struct symtab_and_line sal;
struct expression *exp;
struct block *exp_valid_block;
- struct value *val, *mark;
+ struct value *val, *mark, *val_chain;
struct frame_info *frame;
struct frame_info *prev_frame = NULL;
char *exp_start = NULL;
@@ -5954,6 +5962,27 @@ watch_command_1 (char *arg, int accessfl
exp_valid_block = innermost_block;
mark = value_mark ();
fetch_watchpoint_value (exp, &val, NULL, NULL);
+
+ /* VALUE_MARK gets us the same value as FETCH_WATCHPOINT_VALUE's VAL_CHAIN
+ parameter. Just this way we do not have to VALUE_FREE the chained VALUEs
+ ourselves. */
+ for (val_chain = value_mark ();
+ val_chain != mark;
+ val_chain = value_next (val_chain))
+ if ((VALUE_LVAL (val_chain) == lval_memory
+ && TYPE_CODE (value_type (val_chain)) != TYPE_CODE_FUNC)
+ || VALUE_LVAL (val_chain) == lval_register)
+ break;
+ if (val_chain == mark)
+ {
+ int len;
+
+ len = exp_end - exp_start;
+ while (len > 0 && isspace (exp_start[len - 1]))
+ len--;
+ error (_("Cannot watch constant value %.*s."), len, exp_start);
+ }
+ /* Break the values chain only after its check above. */
if (val != NULL)
release_value (val);
Index: gdb-6.8.50.20090209/gdb/gdbtypes.h
===================================================================
--- gdb-6.8.50.20090209.orig/gdb/gdbtypes.h 2009-02-09 15:51:57.000000000 +0100
+++ gdb-6.8.50.20090209/gdb/gdbtypes.h 2009-02-09 16:04:10.000000000 +0100
@@ -70,7 +70,22 @@ enum type_code
TYPE_CODE_UNION, /* C union or Pascal variant part */
TYPE_CODE_ENUM, /* Enumeration type */
TYPE_CODE_FLAGS, /* Bit flags type */
- TYPE_CODE_FUNC, /* Function type */
+
+ /* Function type. It is not a pointer to a function. Function reference
+ by its name (such as `printf') has this type. C automatically converts
+ this function type to a pointer to function for any operation except
+ `sizeof (function_type)' or `&function_type' (unary &).
+ `sizeof (function_type)' is undefined in C. But GCC provides extension
+ (info '(gcc)Pointer Arith') defining its size as 1 byte. DWARF does not
+ define its size but GDB defines the size the GCC compatible way - GDB
+ function MAKE_FUNCTION_TYPE. The address itself is not modifiable.
+ As the function type has size 1 but its real value has `sizeof
+ (CORE_ADDR)' we cannot use NOT_LVAL category because the address would
+ not fit in the VALUE_CONTENTS_RAW container of its VALUE. We use
+ LVAL_MEMORY (and its VALUE_ADDRESS field) for it but we must be careful
+ it is not lvalue, it is the only non-modifiable LVAL_MEMORY. */
+ TYPE_CODE_FUNC,
+
TYPE_CODE_INT, /* Integer type */
/* Floating type. This is *NOT* a complex type. Beware, there are parts
Index: gdb-6.8.50.20090209/gdb/doc/gdb.texinfo
===================================================================
--- gdb-6.8.50.20090209.orig/gdb/doc/gdb.texinfo 2009-02-09 16:02:42.000000000 +0100
+++ gdb-6.8.50.20090209/gdb/doc/gdb.texinfo 2009-02-09 16:04:10.000000000 +0100
@@ -3480,6 +3480,18 @@ This command prints a list of watchpoint
it is the same as @code{info break} (@pxref{Set Breaks}).
@end table
+If you watch for a change in a numerically entered address you need to
+dereference it as the address itself is just a constant number which will never
+change. @value{GDBN} refuses to create a watchpoint that watches
+a never-changing value:
+
+@smallexample
+(@value{GDBP}) watch 0x600850
+Cannot watch constant value 0x600850.
+(@value{GDBP}) watch *(int *) 0x600850
+Watchpoint 1: *(int *) 6293584
+@end smallexample
+
@value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware
watchpoints execute very quickly, and the debugger reports a change in
value at the exact instruction where the change occurs. If @value{GDBN}
Index: gdb-6.8.50.20090209/gdb/testsuite/gdb.base/watchpoint.c
===================================================================
--- gdb-6.8.50.20090209.orig/gdb/testsuite/gdb.base/watchpoint.c 2008-03-03 14:24:12.000000000 +0100
+++ gdb-6.8.50.20090209/gdb/testsuite/gdb.base/watchpoint.c 2009-02-09 16:04:10.000000000 +0100
@@ -40,6 +40,7 @@ struct foo struct1, struct2, *ptr1, *ptr
int doread = 0;
char *global_ptr;
+char **global_ptr_ptr;
void marker1 ()
{
@@ -118,6 +119,10 @@ func4 ()
buf[0] = 3;
global_ptr = buf;
buf[0] = 7;
+ buf[1] = 5;
+ global_ptr_ptr = &global_ptr;
+ buf[0] = 9;
+ global_ptr++;
}
int main ()
Index: gdb-6.8.50.20090209/gdb/testsuite/gdb.base/watchpoint.exp
===================================================================
--- gdb-6.8.50.20090209.orig/gdb/testsuite/gdb.base/watchpoint.exp 2009-01-03 06:58:03.000000000 +0100
+++ gdb-6.8.50.20090209/gdb/testsuite/gdb.base/watchpoint.exp 2009-02-09 16:05:03.000000000 +0100
@@ -641,7 +641,21 @@ proc test_watchpoint_and_breakpoint {} {
}
}
}
-
+
+proc test_constant_watchpoint {} {
+ global gdb_prompt
+
+ gdb_test "watch 5" "Cannot watch constant value 5." "number is constant"
+ gdb_test "watch marker1" "Cannot watch constant value marker1." \
+ "marker1 is constant"
+ gdb_test "watch count + 6" ".*atchpoint \[0-9\]+: count \\+ 6"
+ gdb_test "set \$expr_breakpoint_number = \$bpnum" ""
+ gdb_test "delete \$expr_breakpoint_number" ""
+ gdb_test "watch 7 + count" ".*atchpoint \[0-9\]+: 7 \\+ count"
+ gdb_test "set \$expr_breakpoint_number = \$bpnum" ""
+ gdb_test "delete \$expr_breakpoint_number" ""
+}
+
proc test_inaccessible_watchpoint {} {
global gdb_prompt
@@ -662,7 +676,8 @@ proc test_inaccessible_watchpoint {} {
}
gdb_test "watch *global_ptr" ".*atchpoint \[0-9\]+: \\*global_ptr"
- gdb_test "next" ".*global_ptr = buf.*"
+ gdb_test "set \$global_ptr_breakpoint_number = \$bpnum" ""
+ gdb_test "next" ".*global_ptr = buf.*" "global_ptr next"
gdb_test_multiple "next" "next over ptr init" {
-re ".*atchpoint \[0-9\]+: \\*global_ptr\r\n\r\nOld value = .*\r\nNew value = 3 .*\r\n.*$gdb_prompt $" {
# We can not test for <unknown> here because NULL may be readable.
@@ -675,6 +690,28 @@ proc test_inaccessible_watchpoint {} {
pass "next over buffer set"
}
}
+ gdb_test "delete \$global_ptr_breakpoint_number" ""
+ gdb_test "watch **global_ptr_ptr" ".*atchpoint \[0-9\]+: \\*\\*global_ptr_ptr"
+ gdb_test "set \$global_ptr_ptr_breakpoint_number = \$bpnum" ""
+ gdb_test "next" ".*global_ptr_ptr = &global_ptr.*" "gloabl_ptr_ptr next"
+ gdb_test_multiple "next" "next over global_ptr_ptr init" {
+ -re ".*atchpoint \[0-9\]+: \\*\\*global_ptr_ptr\r\n\r\nOld value = .*\r\nNew value = 7 .*\r\n.*$gdb_prompt $" {
+ # We can not test for <unknown> here because NULL may be readable.
+ # This test does rely on *NULL != 7.
+ pass "next over global_ptr_ptr init"
+ }
+ }
+ gdb_test_multiple "next" "next over global_ptr_ptr buffer set" {
+ -re ".*atchpoint \[0-9\]+: \\*\\*global_ptr_ptr\r\n\r\nOld value = 7 .*\r\nNew value = 9 .*\r\n.*$gdb_prompt $" {
+ pass "next over global_ptr_ptr buffer set"
+ }
+ }
+ gdb_test_multiple "next" "next over global_ptr_ptr pointer advance" {
+ -re ".*atchpoint \[0-9\]+: \\*\\*global_ptr_ptr\r\n\r\nOld value = 9 .*\r\nNew value = 5 .*\r\n.*$gdb_prompt $" {
+ pass "next over global_ptr_ptr pointer advance"
+ }
+ }
+ gdb_test "delete \$global_ptr_ptr_breakpoint_number" ""
}
}
@@ -842,6 +879,17 @@ if [initialize] then {
}
test_watchpoint_and_breakpoint
+
+ # See above.
+ if [istarget "mips-idt-*"] then {
+ gdb_exit
+ gdb_start
+ gdb_reinitialize_dir $srcdir/$subdir
+ gdb_load $binfile
+ initialize
+ }
+
+ test_constant_watchpoint
}
# Restore old timeout