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2004-11-04 Jim Blandy <jimb@redhat.com>
* gdbtypes.c (make_qualified_type): Doc fix. Add assertion to
prevent cross-objfile references.
(make_cv_type): Doc fix. Don't create cross-objfile references,
even for stub types.
(replace_type): Add assertion to prevent cross-objfile references.
(check_typedef): Never resolve a stub type by copying over a type
from another file.
Index: src/gdb/gdbtypes.c
===================================================================
RCS file: /big/fsf/rsync/src-cvs/src/gdb/gdbtypes.c,v
retrieving revision 1.92
retrieving revision 1.93
diff -u -p -r1.92 -r1.93
--- src/gdb/gdbtypes.c 8 Aug 2004 17:18:16 -0000 1.92
+++ src/gdb/gdbtypes.c 4 Nov 2004 17:50:16 -0000 1.93
@@ -433,7 +433,9 @@ address_space_int_to_name (int space_fla
}
/* Create a new type with instance flags NEW_FLAGS, based on TYPE.
- If STORAGE is non-NULL, create the new type instance there. */
+
+ If STORAGE is non-NULL, create the new type instance there.
+ STORAGE must be in the same obstack as TYPE. */
static struct type *
make_qualified_type (struct type *type, int new_flags,
@@ -453,6 +455,12 @@ make_qualified_type (struct type *type,
ntype = alloc_type_instance (type);
else
{
+ /* If STORAGE was provided, it had better be in the same objfile as
+ TYPE. Otherwise, we can't link it into TYPE's cv chain: if one
+ objfile is freed and the other kept, we'd have dangling
+ pointers. */
+ gdb_assert (TYPE_OBJFILE (type) == TYPE_OBJFILE (storage));
+
ntype = storage;
TYPE_MAIN_TYPE (ntype) = TYPE_MAIN_TYPE (type);
TYPE_CHAIN (ntype) = ntype;
@@ -501,11 +509,12 @@ make_type_with_address_space (struct typ
CNST is a flag for setting the const attribute
VOLTL is a flag for setting the volatile attribute
TYPE is the base type whose variant we are creating.
- TYPEPTR, if nonzero, points
- to a pointer to memory where the reference type should be stored.
- If *TYPEPTR is zero, update it to point to the reference type we return.
- We allocate new memory if needed. */
+ If TYPEPTR and *TYPEPTR are non-zero, then *TYPEPTR points to
+ storage to hold the new qualified type; *TYPEPTR and TYPE must be
+ in the same objfile. Otherwise, allocate fresh memory for the new
+ type whereever TYPE lives. If TYPEPTR is non-zero, set it to the
+ new type we construct. */
struct type *
make_cv_type (int cnst, int voltl, struct type *type, struct type **typeptr)
{
@@ -524,20 +533,19 @@ make_cv_type (int cnst, int voltl, struc
if (typeptr && *typeptr != NULL)
{
- /* Objfile is per-core-type. This const-qualified type had best
- belong to the same objfile as the type it is qualifying, unless
- we are overwriting a stub type, in which case the safest thing
- to do is to copy the core type into the new objfile. */
-
- gdb_assert (TYPE_OBJFILE (*typeptr) == TYPE_OBJFILE (type)
- || TYPE_STUB (*typeptr));
- if (TYPE_OBJFILE (*typeptr) != TYPE_OBJFILE (type))
- {
- TYPE_MAIN_TYPE (*typeptr)
- = TYPE_ALLOC (*typeptr, sizeof (struct main_type));
- *TYPE_MAIN_TYPE (*typeptr)
- = *TYPE_MAIN_TYPE (type);
- }
+ /* TYPE and *TYPEPTR must be in the same objfile. We can't have
+ a C-V variant chain that threads across objfiles: if one
+ objfile gets freed, then the other has a broken C-V chain.
+
+ This code used to try to copy over the main type from TYPE to
+ *TYPEPTR if they were in different objfiles, but that's
+ wrong, too: TYPE may have a field list or member function
+ lists, which refer to types of their own, etc. etc. The
+ whole shebang would need to be copied over recursively; you
+ can't have inter-objfile pointers. The only thing to do is
+ to leave stub types as stub types, and look them up afresh by
+ name each time you encounter them. */
+ gdb_assert (TYPE_OBJFILE (*typeptr) == TYPE_OBJFILE (type));
}
ntype = make_qualified_type (type, new_flags, typeptr ? *typeptr : NULL);
@@ -562,6 +570,12 @@ replace_type (struct type *ntype, struct
{
struct type *chain;
+ /* These two types had better be in the same objfile. Otherwise,
+ the assignment of one type's main type structure to the other
+ will produce a type with references to objects (names; field
+ lists; etc.) allocated on an objfile other than its own. */
+ gdb_assert (TYPE_OBJFILE (ntype) == TYPE_OBJFILE (ntype));
+
*TYPE_MAIN_TYPE (ntype) = *TYPE_MAIN_TYPE (type);
/* The type length is not a part of the main type. Update it for each
@@ -1416,8 +1430,24 @@ check_typedef (struct type *type)
return type;
}
newtype = lookup_transparent_type (name);
+
if (newtype)
- make_cv_type (is_const, is_volatile, newtype, &type);
+ {
+ /* If the resolved type and the stub are in the same objfile,
+ then replace the stub type with the real deal. But if
+ they're in separate objfiles, leave the stub alone; we'll
+ just look up the transparent type every time we call
+ check_typedef. We can't create pointers between types
+ allocated to different objfiles, since they may have
+ different lifetimes. Trying to copy NEWTYPE over to TYPE's
+ objfile is pointless, too, since you'll have to move over any
+ other types NEWTYPE refers to, which could be an unbounded
+ amount of stuff. */
+ if (TYPE_OBJFILE (newtype) == TYPE_OBJFILE (type))
+ make_cv_type (is_const, is_volatile, newtype, &type);
+ else
+ type = newtype;
+ }
}
/* Otherwise, rely on the stub flag being set for opaque/stubbed types */
else if (TYPE_STUB (type) && !currently_reading_symtab)
|
