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authorJohn Gilmore <gnu@cygnus>1992-10-06 09:22:43 +0000
committerJohn Gilmore <gnu@cygnus>1992-10-06 09:22:43 +0000
commit94603999f966820f5264e98e530cb59c38597963 (patch)
treebbb9e731f62c217daec96656e23a6c1191de9efb /gdb/values.c
parent3d3e494e4c586428ffe396ef58b6c5a4789edc3c (diff)
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A bunch of changes mostly to improve debugging of C++ programs.
Specifically, the calling of inferiors methods is improved. * value.h: New macros METHOD_PTR_IS_VIRTUAL, METHOD_PTR_FROM_VOFFSET, METHOD_PTR_TO_VOFFSET to partially hide the implementation details of pointer-to-method objects. How to tell if the pointer points to a virtual method is still very dependent on the particular compiler, but this should make it easier to find the places to change. * eval.c (evaluate_subexp [case OP_FUNCALL]), valprint.c (val_print [case TYPE_CODE_PTR]): Use the new METHOD_PTR_* macros, instead of a hard-wired-in code that incorrectly assumed a no-longerused representation of pointer-to-method values. And otherwise fix the relevant bit-rotted code. * valprint.c (type_print_base [case TYPE_CODE_STRUCT]): If there are both fields and methods, put a space between. * stabsread.c (read_struct_type): Fix bug in handling of GNU C++ anonymous type (indicated by CPLUS_MARKER followed by '_'). (It used to prematurely exit the loop reading in the fields, so it would think it should start reading methods while still in the fields. This could crash gdb given a gcc that can emit nested type information.) * valops.c (search_struct_method): Pass 'this' value by reference instead of by value. This provides a more consistent interface through a recursive search where the "bottom" functions may need to adjust offsets (due to multiple inheritance). * valops.c, value.h, values.c: Pass extra parameters to value_fn_field and value_virtual_fn_field so we can correctly adjust offset for multiple inheritance. * eval.c (evaluate_subexp [case OP_FUNCALL]): Simplify virtual function calls by using value_virtual_fn_field(). * values.c: New function baseclass_offset, derived from baseclass_addr (which perhaps can be made obsolete?). It returns an offset rather than an address. This is a cleaner interface since it doesn't mess around allocating new values. * valops.c (search_struct_method): Use baseclass_offset rather than baseclass_addr.
Diffstat (limited to 'gdb/values.c')
-rw-r--r--gdb/values.c100
1 files changed, 91 insertions, 9 deletions
diff --git a/gdb/values.c b/gdb/values.c
index 8c299cc..aaff4126 100644
--- a/gdb/values.c
+++ b/gdb/values.c
@@ -903,12 +903,15 @@ value_field (arg1, fieldno)
J is an index into F which provides the desired method. */
value
-value_fn_field (f, j)
+value_fn_field (arg1p, f, j, type, offset)
+ value *arg1p;
struct fn_field *f;
int j;
+ struct type *type;
+ int offset;
{
register value v;
- register struct type *type = TYPE_FN_FIELD_TYPE (f, j);
+ register struct type *ftype = TYPE_FN_FIELD_TYPE (f, j);
struct symbol *sym;
sym = lookup_symbol (TYPE_FN_FIELD_PHYSNAME (f, j),
@@ -916,27 +919,40 @@ value_fn_field (f, j)
if (! sym) error ("Internal error: could not find physical method named %s",
TYPE_FN_FIELD_PHYSNAME (f, j));
- v = allocate_value (type);
+ v = allocate_value (ftype);
VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
- VALUE_TYPE (v) = type;
+ VALUE_TYPE (v) = ftype;
+
+ if (arg1p)
+ {
+ if (type != VALUE_TYPE (*arg1p))
+ *arg1p = value_ind (value_cast (lookup_pointer_type (type),
+ value_addr (*arg1p)));
+
+ /* Move the `this' pointer according to the offset. */
+ VALUE_OFFSET (*arg1p) += offset;
+ }
+
return v;
}
/* Return a virtual function as a value.
ARG1 is the object which provides the virtual function
- table pointer. ARG1 is side-effected in calling this function.
+ table pointer. *ARG1P is side-effected in calling this function.
F is the list of member functions which contains the desired virtual
function.
J is an index into F which provides the desired virtual function.
TYPE is the type in which F is located. */
value
-value_virtual_fn_field (arg1, f, j, type)
- value arg1;
+value_virtual_fn_field (arg1p, f, j, type, offset)
+ value *arg1p;
struct fn_field *f;
int j;
struct type *type;
+ int offset;
{
+ value arg1 = *arg1p;
/* First, get the virtual function table pointer. That comes
with a strange type, so cast it to type `pointer to long' (which
should serve just fine as a function type). Then, index into
@@ -968,7 +984,9 @@ value_virtual_fn_field (arg1, f, j, type)
/* The virtual function table is now an array of structures
which have the form { int16 offset, delta; void *pfn; }. */
- vtbl = value_ind (value_field (arg1, TYPE_VPTR_FIELDNO (context)));
+ vtbl = value_ind (value_primitive_field (arg1, 0,
+ TYPE_VPTR_FIELDNO (context),
+ TYPE_VPTR_BASETYPE (context)));
/* Index into the virtual function table. This is hard-coded because
looking up a field is not cheap, and it may be important to save
@@ -977,7 +995,7 @@ value_virtual_fn_field (arg1, f, j, type)
entry = value_subscript (vtbl, vi);
/* Move the `this' pointer according to the virtual function table. */
- VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0));
+ VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0)) + offset;
if (! VALUE_LAZY (arg1))
{
VALUE_LAZY (arg1) = 1;
@@ -988,6 +1006,7 @@ value_virtual_fn_field (arg1, f, j, type)
/* Reinstantiate the function pointer with the correct type. */
VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j));
+ *arg1p = arg1;
return vfn;
}
@@ -1103,6 +1122,67 @@ value_from_vtable_info (arg, type)
return value_headof (arg, 0, type);
}
+/* Compute the offset of the baseclass which is
+ the INDEXth baseclass of class TYPE, for a value ARG,
+ wih extra offset of OFFSET.
+ The result is the offste of the baseclass value relative
+ to (the address of)(ARG) + OFFSET.
+
+ -1 is returned on error. */
+
+int
+baseclass_offset (type, index, arg, offset)
+ struct type *type;
+ int index;
+ value arg;
+ int offset;
+{
+ struct type *basetype = TYPE_BASECLASS (type, index);
+
+ if (BASETYPE_VIA_VIRTUAL (type, index))
+ {
+ /* Must hunt for the pointer to this virtual baseclass. */
+ register int i, len = TYPE_NFIELDS (type);
+ register int n_baseclasses = TYPE_N_BASECLASSES (type);
+ char *vbase_name, *type_name = type_name_no_tag (basetype);
+
+ vbase_name = (char *)alloca (strlen (type_name) + 8);
+ sprintf (vbase_name, "_vb%c%s", CPLUS_MARKER, type_name);
+ /* First look for the virtual baseclass pointer
+ in the fields. */
+ for (i = n_baseclasses; i < len; i++)
+ {
+ if (! strcmp (vbase_name, TYPE_FIELD_NAME (type, i)))
+ {
+ CORE_ADDR addr
+ = unpack_pointer (TYPE_FIELD_TYPE (type, i),
+ VALUE_CONTENTS (arg) + VALUE_OFFSET (arg)
+ + offset
+ + (TYPE_FIELD_BITPOS (type, i) / 8));
+
+ if (VALUE_LVAL (arg) != lval_memory)
+ return -1;
+
+ return addr -
+ (LONGEST) (VALUE_ADDRESS (arg) + VALUE_OFFSET (arg) + offset);
+ }
+ }
+ /* Not in the fields, so try looking through the baseclasses. */
+ for (i = index+1; i < n_baseclasses; i++)
+ {
+ int boffset =
+ baseclass_offset (type, i, arg, offset);
+ if (boffset)
+ return boffset;
+ }
+ /* Not found. */
+ return -1;
+ }
+
+ /* Baseclass is easily computed. */
+ return TYPE_BASECLASS_BITPOS (type, index) / 8;
+}
+
/* Compute the address of the baseclass which is
the INDEXth baseclass of class TYPE. The TYPE base
of the object is at VALADDR.
@@ -1112,6 +1192,8 @@ value_from_vtable_info (arg, type)
of the baseclasss, but the address which could not be read
successfully. */
+/* FIXME Fix remaining uses of baseclass_addr to use baseclass_offset */
+
char *
baseclass_addr (type, index, valaddr, valuep, errp)
struct type *type;