Compute proper length for dynamic types of TYPE_CODE_TYPEDEF
Commit Message
This patch fixes gdb/21356 in which we hit an assertion in
value_contents_bits_eq:
(gdb) p container_object2
(gdb) p container_object2
$1 = {_container_member2 = 15, _vla_struct_object2 = {_some_member = 0,
_vla_field = {
../../src/gdb/value.c:829: internal-error: int value_contents_bits_eq(const value*, int, const value*, int, int): Assertion `offset1 + length <= TYPE_LENGTH (val1->enclosing_type) * TARGET_CHAR_BIT' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
This is happening because TYPE_LENGTH (val1->enclosing_type) is erroneously
based on enclosing_type, which is a typedef, instead of the actual underlying
type.
This can be traced back to resolve_dynamic_struct, where the size of the
type is computed:
2093 TYPE_FIELD_TYPE (resolved_type, i)
2094 = resolve_dynamic_type_internal (TYPE_FIELD_TYPE (resolved_type, i),
2095 &pinfo, 0);
2096 gdb_assert (TYPE_FIELD_LOC_KIND (resolved_type, i)
2097 == FIELD_LOC_KIND_BITPOS);
2098
2099 new_bit_length = TYPE_FIELD_BITPOS (resolved_type, i);
2100 if (TYPE_FIELD_BITSIZE (resolved_type, i) != 0)
2101 new_bit_length += TYPE_FIELD_BITSIZE (resolved_type, i);
2102 else
2103 new_bit_length += (TYPE_LENGTH (TYPE_FIELD_TYPE (resolved_type, i))
2104 * TARGET_CHAR_BIT);
In this function, resolved_type is TYPE_CODE_TYPEDEF which is not what we
want to use to calculate the size of the actual field.
This patch fixes this and the similar problem in resolve_dynamic_union.
gdb/ChangeLog:
yyyy-mm-dd Keith Seitz <keiths@redhat.com>
PR gdb/21356
* gdbtypes.c (resolve_dynamic_union, resolve_dynamic_struct):
Resolve typedefs for type length calculations.
gdb/testsuite/ChangeLog:
yyyy-mm-dd Keith Seitz <keiths@redhat.com>
PR gdb/21356
* gdb.base/vla-datatypes.c (vla_factory): Add typedef for struct
vla_struct.
Add new struct vla_typedef and unin vla_typedef_union and
corresponding instantiation objects.
Initialize new objects.
* gdb.base/vla-datatypes.exp: Add tests for vla_typedef_struct_object
and vla_typedef_union_object.
Fixup type for vla_struct_object.
---
gdb/gdbtypes.c | 14 ++++++++++----
gdb/testsuite/gdb.base/vla-datatypes.c | 21 +++++++++++++++++++--
gdb/testsuite/gdb.base/vla-datatypes.exp | 6 +++++-
3 files changed, 34 insertions(+), 7 deletions(-)
Comments
Hi Keith,
On 06/24/2017 01:59 AM, Keith Seitz wrote:
> --- a/gdb/testsuite/gdb.base/vla-datatypes.c
> +++ b/gdb/testsuite/gdb.base/vla-datatypes.c
> @@ -46,11 +46,12 @@ vla_factory (int n)
> BAR bar_vla[n];
> int i;
>
> - struct vla_struct
> + typedef struct vla_struct
> {
> int something;
> int vla_field[n];
> - } vla_struct_object;
> + } vla_s;
> + vla_s vla_struct_object;
This object is now defined with a typedef type, and that confused me a lot.
After staring at this for a while, I think you did intend that. I just
find the naming very confusing. Can we improve on that? Maybe add
some comments too.
>
> struct inner_vla_struct
> {
> @@ -59,14 +60,28 @@ vla_factory (int n)
> int after;
> } inner_vla_struct_object;
>
> + struct vla_typedef
... because this type is called "typedef", while
the above isn't.
> + {
> + int something;
> + vla_s vla_object;
> + } vla_typedef_struct_object;
... and this object here is not a a type that is
defined as a typedef, while it's named "..._typedef_...".
So at first is looked like you have the "typedef vs non-typedef"
cases backwards. I understand now that you're referring to
the "vla_object" member, but it was totally non-obvious to me.
Can we rename things a bit to avoid this confusion?
Maybe
struct vla_typedef -> struct vla_s_struct_member
union vla_typedef_union -> union vla_s_union_member
?
and add some comment about using "vla_s" throughout
because it's a typedef. And/or rename it
to "vla_struct_typedef".
Thanks,
Pedro Alves
@@ -2033,8 +2033,10 @@ resolve_dynamic_union (struct type *type,
t = resolve_dynamic_type_internal (TYPE_FIELD_TYPE (resolved_type, i),
addr_stack, 0);
TYPE_FIELD_TYPE (resolved_type, i) = t;
- if (TYPE_LENGTH (t) > max_len)
- max_len = TYPE_LENGTH (t);
+
+ struct type *real_type = check_typedef (t);
+ if (TYPE_LENGTH (real_type) > max_len)
+ max_len = TYPE_LENGTH (real_type);
}
TYPE_LENGTH (resolved_type) = max_len;
@@ -2100,8 +2102,12 @@ resolve_dynamic_struct (struct type *type,
if (TYPE_FIELD_BITSIZE (resolved_type, i) != 0)
new_bit_length += TYPE_FIELD_BITSIZE (resolved_type, i);
else
- new_bit_length += (TYPE_LENGTH (TYPE_FIELD_TYPE (resolved_type, i))
- * TARGET_CHAR_BIT);
+ {
+ struct type *real_type
+ = check_typedef (TYPE_FIELD_TYPE (resolved_type, i));
+
+ new_bit_length += (TYPE_LENGTH (real_type) * TARGET_CHAR_BIT);
+ }
/* Normally, we would use the position and size of the last field
to determine the size of the enclosing structure. But GCC seems
@@ -46,11 +46,12 @@ vla_factory (int n)
BAR bar_vla[n];
int i;
- struct vla_struct
+ typedef struct vla_struct
{
int something;
int vla_field[n];
- } vla_struct_object;
+ } vla_s;
+ vla_s vla_struct_object;
struct inner_vla_struct
{
@@ -59,14 +60,28 @@ vla_factory (int n)
int after;
} inner_vla_struct_object;
+ struct vla_typedef
+ {
+ int something;
+ vla_s vla_object;
+ } vla_typedef_struct_object;
+
union vla_union
{
int vla_field[n];
} vla_union_object;
+ union vla_typedef_union
+ {
+ int something;
+ vla_s vla_object;
+ } vla_typedef_union_object;
+
vla_struct_object.something = n;
inner_vla_struct_object.something = n;
inner_vla_struct_object.after = n;
+ vla_typedef_struct_object.something = n * 2;
+ vla_typedef_struct_object.vla_object.something = n * 3;
for (i = 0; i < n; i++)
{
int_vla[i] = i*2;
@@ -85,6 +100,8 @@ vla_factory (int n)
vla_struct_object.vla_field[i] = i*2;
vla_union_object.vla_field[i] = i*2;
inner_vla_struct_object.vla_field[i] = i*2;
+ vla_typedef_struct_object.vla_object.vla_field[i] = i * 3;
+ vla_typedef_union_object.vla_object.vla_field[i] = i * 3 - 1;
}
size_t int_size = sizeof(int_vla); /* vlas_filled */
@@ -57,6 +57,10 @@ gdb_test "print vla_struct_object" \
"\\\{something = 5, vla_field = \\\{0, 2, 4, 6, 8\\\}\\\}"
gdb_test "print vla_union_object" \
"\\\{vla_field = \\\{0, 2, 4, 6, 8\\\}\\\}"
+gdb_test "print vla_typedef_struct_object" \
+ "\\\{something = 10, vla_object = \\\{something = 15, vla_field = \\\{0, 3, 6, 9, 12\\\}\\\}\\\}"
+gdb_test "print vla_typedef_union_object" \
+ "\\\{something = 6, vla_object = \\\{something = 6, vla_field = \\\{-1, 2, 5, 8, 11\\\}\\\}\\\}"
# Check whatis of VLA's.
gdb_test "whatis int_vla" "type = int \\\[5\\\]" "whatis int_vla"
@@ -78,7 +82,7 @@ gdb_test "whatis unsigned_char_vla" "type = unsigned char \\\[5\\\]" \
"whatis unsigned_char_vla"
gdb_test "whatis foo_vla" "type = struct foo \\\[5\\\]" "whatis foo_vla"
gdb_test "whatis bar_vla" "type = BAR \\\[5\\\]" "whatis bar_vla"
-gdb_test "whatis vla_struct_object" "type = struct vla_struct"
+gdb_test "whatis vla_struct_object" "type = vla_s"
gdb_test "whatis vla_union_object" "type = union vla_union"
# Check ptype of VLA's.