422 lines
13 KiB
C
422 lines
13 KiB
C
/* Abstraction of GNU v2 abi.
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Copyright (C) 2001-2018 Free Software Foundation, Inc.
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Contributed by Daniel Berlin <dberlin@redhat.com>
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "symtab.h"
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#include "gdbtypes.h"
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#include "value.h"
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#include "demangle.h"
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#include "gdb-demangle.h"
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#include "cp-abi.h"
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#include "cp-support.h"
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#include <ctype.h>
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struct cp_abi_ops gnu_v2_abi_ops;
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static int vb_match (struct type *, int, struct type *);
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static enum dtor_kinds
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gnuv2_is_destructor_name (const char *name)
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{
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if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_')
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|| startswith (name, "__dt__"))
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return complete_object_dtor;
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else
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return (enum dtor_kinds) 0;
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}
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static enum ctor_kinds
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gnuv2_is_constructor_name (const char *name)
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{
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if ((name[0] == '_' && name[1] == '_'
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&& (isdigit (name[2]) || strchr ("Qt", name[2])))
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|| startswith (name, "__ct__"))
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return complete_object_ctor;
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else
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return (enum ctor_kinds) 0;
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}
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static int
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gnuv2_is_vtable_name (const char *name)
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{
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return (((name)[0] == '_'
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&& (((name)[1] == 'V' && (name)[2] == 'T')
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|| ((name)[1] == 'v' && (name)[2] == 't'))
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&& is_cplus_marker ((name)[3])) ||
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((name)[0] == '_' && (name)[1] == '_'
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&& (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_'));
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}
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static int
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gnuv2_is_operator_name (const char *name)
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{
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return startswith (name, CP_OPERATOR_STR);
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}
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/* Return a virtual function as a value.
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ARG1 is the object which provides the virtual function
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table pointer. *ARG1P is side-effected in calling this function.
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F is the list of member functions which contains the desired virtual
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function.
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J is an index into F which provides the desired virtual function.
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TYPE is the type in which F is located. */
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static struct value *
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gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,
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struct type * type, int offset)
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{
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struct value *arg1 = *arg1p;
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struct type *type1 = check_typedef (value_type (arg1));
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struct type *entry_type;
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/* First, get the virtual function table pointer. That comes
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with a strange type, so cast it to type `pointer to long' (which
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should serve just fine as a function type). Then, index into
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the table, and convert final value to appropriate function type. */
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struct value *entry;
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struct value *vfn;
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struct value *vtbl;
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LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j);
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struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
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struct type *context;
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struct type *context_vptr_basetype;
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int context_vptr_fieldno;
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if (fcontext == NULL)
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/* We don't have an fcontext (e.g. the program was compiled with
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g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
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This won't work right for multiple inheritance, but at least we
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should do as well as GDB 3.x did. */
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fcontext = TYPE_VPTR_BASETYPE (type);
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context = lookup_pointer_type (fcontext);
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/* Now context is a pointer to the basetype containing the vtbl. */
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if (TYPE_TARGET_TYPE (context) != type1)
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{
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struct value *tmp = value_cast (context, value_addr (arg1));
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arg1 = value_ind (tmp);
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type1 = check_typedef (value_type (arg1));
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}
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context = type1;
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/* Now context is the basetype containing the vtbl. */
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/* This type may have been defined before its virtual function table
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was. If so, fill in the virtual function table entry for the
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type now. */
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context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype);
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/* FIXME: What to do if vptr_fieldno is still -1? */
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/* The virtual function table is now an array of structures
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which have the form { int16 offset, delta; void *pfn; }. */
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vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno,
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context_vptr_basetype);
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/* With older versions of g++, the vtbl field pointed to an array
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of structures. Nowadays it points directly to the structure. */
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if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR
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&& TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY)
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{
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/* Handle the case where the vtbl field points to an
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array of structures. */
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vtbl = value_ind (vtbl);
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/* Index into the virtual function table. This is hard-coded because
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looking up a field is not cheap, and it may be important to save
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time, e.g. if the user has set a conditional breakpoint calling
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a virtual function. */
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entry = value_subscript (vtbl, vi);
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}
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else
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{
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/* Handle the case where the vtbl field points directly to a
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structure. */
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vtbl = value_ptradd (vtbl, vi);
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entry = value_ind (vtbl);
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}
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entry_type = check_typedef (value_type (entry));
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if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
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{
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/* Move the `this' pointer according to the virtual function table. */
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set_value_offset (arg1, value_offset (arg1)
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+ value_as_long (value_field (entry, 0)));
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if (!value_lazy (arg1))
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{
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set_value_lazy (arg1, 1);
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value_fetch_lazy (arg1);
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}
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vfn = value_field (entry, 2);
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}
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else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
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vfn = entry;
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else
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error (_("I'm confused: virtual function table has bad type"));
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/* Reinstantiate the function pointer with the correct type. */
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deprecated_set_value_type (vfn,
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lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)));
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*arg1p = arg1;
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return vfn;
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}
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static struct type *
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gnuv2_value_rtti_type (struct value *v, int *full, LONGEST *top, int *using_enc)
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{
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struct type *known_type;
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struct type *rtti_type;
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CORE_ADDR vtbl;
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struct bound_minimal_symbol minsym;
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char *demangled_name, *p;
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const char *linkage_name;
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struct type *btype;
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struct type *known_type_vptr_basetype;
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int known_type_vptr_fieldno;
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if (full)
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*full = 0;
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if (top)
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*top = -1;
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if (using_enc)
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*using_enc = 0;
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/* Get declared type. */
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known_type = value_type (v);
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known_type = check_typedef (known_type);
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/* RTTI works only or class objects. */
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if (TYPE_CODE (known_type) != TYPE_CODE_STRUCT)
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return NULL;
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/* Plan on this changing in the future as i get around to setting
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the vtables properly for G++ compiled stuff. Also, I'll be using
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the type info functions, which are always right. Deal with it
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until then. */
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/* Try to get the vptr basetype, fieldno. */
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known_type_vptr_fieldno = get_vptr_fieldno (known_type,
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&known_type_vptr_basetype);
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/* If we can't find it, give up. */
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if (known_type_vptr_fieldno < 0)
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return NULL;
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/* Make sure our basetype and known type match, otherwise, cast
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so we can get at the vtable properly. */
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btype = known_type_vptr_basetype;
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btype = check_typedef (btype);
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if (btype != known_type )
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{
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v = value_cast (btype, v);
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if (using_enc)
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*using_enc=1;
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}
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/* We can't use value_ind here, because it would want to use RTTI, and
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we'd waste a bunch of time figuring out we already know the type.
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Besides, we don't care about the type, just the actual pointer. */
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if (value_address (value_field (v, known_type_vptr_fieldno)) == 0)
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return NULL;
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vtbl = value_as_address (value_field (v, known_type_vptr_fieldno));
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/* Try to find a symbol that is the vtable. */
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minsym=lookup_minimal_symbol_by_pc(vtbl);
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if (minsym.minsym==NULL
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|| (linkage_name=MSYMBOL_LINKAGE_NAME (minsym.minsym))==NULL
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|| !is_vtable_name (linkage_name))
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return NULL;
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/* If we just skip the prefix, we get screwed by namespaces. */
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demangled_name=gdb_demangle(linkage_name,DMGL_PARAMS|DMGL_ANSI);
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p = strchr (demangled_name, ' ');
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if (p)
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*p = '\0';
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/* Lookup the type for the name. */
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/* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
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rtti_type = cp_lookup_rtti_type (demangled_name, NULL);
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if (rtti_type == NULL)
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return NULL;
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if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1)
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{
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if (top)
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*top = TYPE_BASECLASS_BITPOS (rtti_type,
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TYPE_VPTR_FIELDNO(rtti_type)) / 8;
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if (top && ((*top) >0))
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{
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if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
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{
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if (full)
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*full=0;
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}
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else
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{
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if (full)
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*full=1;
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}
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}
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}
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else
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{
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if (full)
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*full=1;
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}
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return rtti_type;
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}
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/* Return true if the INDEXth field of TYPE is a virtual baseclass
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pointer which is for the base class whose type is BASECLASS. */
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static int
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vb_match (struct type *type, int index, struct type *basetype)
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{
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struct type *fieldtype;
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const char *name = TYPE_FIELD_NAME (type, index);
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const char *field_class_name = NULL;
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if (*name != '_')
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return 0;
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/* gcc 2.4 uses _vb$. */
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if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3]))
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field_class_name = name + 4;
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/* gcc 2.5 will use __vb_. */
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if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_')
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field_class_name = name + 5;
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if (field_class_name == NULL)
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/* This field is not a virtual base class pointer. */
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return 0;
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/* It's a virtual baseclass pointer, now we just need to find out whether
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it is for this baseclass. */
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fieldtype = TYPE_FIELD_TYPE (type, index);
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if (fieldtype == NULL
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|| TYPE_CODE (fieldtype) != TYPE_CODE_PTR)
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/* "Can't happen". */
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return 0;
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/* What we check for is that either the types are equal (needed for
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nameless types) or have the same name. This is ugly, and a more
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elegant solution should be devised (which would probably just push
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the ugliness into symbol reading unless we change the stabs format). */
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if (TYPE_TARGET_TYPE (fieldtype) == basetype)
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return 1;
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if (TYPE_NAME (basetype) != NULL
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&& TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL
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&& strcmp (TYPE_NAME (basetype),
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TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0)
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return 1;
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return 0;
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}
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/* Compute the offset of the baseclass which is the INDEXth baseclass
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of class TYPE, for value at VALADDR (in host) at ADDRESS (in
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target). The result is the offset of the baseclass value relative
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to (the address of)(ARG) + OFFSET. */
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static int
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gnuv2_baseclass_offset (struct type *type, int index,
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const bfd_byte *valaddr, LONGEST embedded_offset,
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CORE_ADDR address, const struct value *val)
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{
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struct type *basetype = TYPE_BASECLASS (type, index);
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if (BASETYPE_VIA_VIRTUAL (type, index))
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{
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/* Must hunt for the pointer to this virtual baseclass. */
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int i, len = TYPE_NFIELDS (type);
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int n_baseclasses = TYPE_N_BASECLASSES (type);
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/* First look for the virtual baseclass pointer
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in the fields. */
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for (i = n_baseclasses; i < len; i++)
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{
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if (vb_match (type, i, basetype))
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{
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struct type *field_type;
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LONGEST field_offset;
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int field_length;
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CORE_ADDR addr;
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field_type = check_typedef (TYPE_FIELD_TYPE (type, i));
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field_offset = TYPE_FIELD_BITPOS (type, i) / 8;
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field_length = TYPE_LENGTH (field_type);
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if (!value_bytes_available (val, embedded_offset + field_offset,
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field_length))
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throw_error (NOT_AVAILABLE_ERROR,
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_("Virtual baseclass pointer is not available"));
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addr = unpack_pointer (field_type,
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valaddr + embedded_offset + field_offset);
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return addr - (LONGEST) address + embedded_offset;
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}
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}
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/* Not in the fields, so try looking through the baseclasses. */
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for (i = index + 1; i < n_baseclasses; i++)
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{
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/* Don't go through baseclass_offset, as that wraps
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exceptions, thus, inner exceptions would be wrapped more
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than once. */
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int boffset =
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gnuv2_baseclass_offset (type, i, valaddr,
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embedded_offset, address, val);
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if (boffset)
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return boffset;
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}
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error (_("Baseclass offset not found"));
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}
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/* Baseclass is easily computed. */
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return TYPE_BASECLASS_BITPOS (type, index) / 8;
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}
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static void
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init_gnuv2_ops (void)
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{
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gnu_v2_abi_ops.shortname = "gnu-v2";
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gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
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gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
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gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;
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gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;
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gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;
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gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;
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gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;
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gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;
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gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset;
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}
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void
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_initialize_gnu_v2_abi (void)
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{
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init_gnuv2_ops ();
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register_cp_abi (&gnu_v2_abi_ops);
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}
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