mirror/gcc
2
0
Fork 0
mirror of git://gcc.gnu.org/git/gcc.git synced 2024-12-22 20:40:12 +08:00
Code Issues Packages Projects Releases Wiki Activity
aa17a5f382
gcc/libstdc++/tinfo.cc
Richard Henderson 9ab916b8ed del_op.cc, [...]: New files. 
* del_op.cc, del_opnt.cc, del_opv.cc, del_opvnt.cc: New files.
        * exception.cc, new_handler.cc, new_op.cc, new_opnt.cc: New files.
        * new_opv.cc, new_opvnt.cc, tinfo.cc, tinfo2.cc, vec.cc: New files.
        * cxxabi.h, exception, new, new.h, typeinfo, pure.c: New files.
        * tinfo.hP: New file.

        * Makefile.in (OBJS, HEADERS): Add new files.
        * configure.in (XCXXINCLUDES): Add ../include and ../gcc.

From-SVN: r36780
2000-10-07 12:21:05 -07:00

1211 lines
43 KiB
C++
Raw Blame History

// Methods for type_info for -*- C++ -*- Run Time Type Identification.
// Copyright (C) 1994, 1996, 1998, 1999, 2000 Free Software Foundation
// This file is part of GNU CC.
// GNU CC is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
// GNU CC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with GNU CC; see the file COPYING. If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
#pragma implementation "typeinfo"
#include <stddef.h>
#include "tinfo.hP"
#include "new" // for placement new
// This file contains the minimal working set necessary to link with code
// that uses virtual functions and -frtti but does not actually use RTTI
// functionality.
std::type_info::
~type_info ()
{ }
#if !defined(__GXX_ABI_VERSION) || __GXX_ABI_VERSION < 100
// original (old) abi
namespace
{
// ADDR is a pointer to an object. Convert it to a pointer to a base,
// using OFFSET.
inline void*
convert_to_base (void *addr, bool is_virtual, myint32 offset)
{
if (!addr)
return NULL;
if (!is_virtual)
return (char *) addr + offset;
// Under the old ABI, the offset gives us the address of a pointer
// to the virtual base.
return *((void **) ((char *) addr + offset));
}
}
// We can't rely on common symbols being shared between shared objects.
bool std::type_info::
operator== (const std::type_info& arg) const
{
return (&arg == this) || (__builtin_strcmp (name (), arg.name ()) == 0);
}
extern "C" void
__rtti_class (void *addr, const char *name,
const __class_type_info::base_info *bl, size_t bn)
{ new (addr) __class_type_info (name, bl, bn); }
extern "C" void
__rtti_si (void *addr, const char *n, const std::type_info *ti)
{
new (addr) __si_type_info
(n, static_cast <const __user_type_info &> (*ti));
}
extern "C" void
__rtti_user (void *addr, const char *name)
{ new (addr) __user_type_info (name); }
// Upcast for catch checking. OBJPTR points to the thrown object and might be
// NULL. Return 0 on failure, non-zero on success. Set *ADJPTR to adjusted
// object pointer.
int __user_type_info::
upcast (const type_info &target, void *objptr,
void **adjptr) const
{
upcast_result result;
if (do_upcast (contained_public, target, objptr, result))
return 0;
*adjptr = result.target_obj;
return contained_public_p (result.whole2target);
}
// Down or cross cast for dynamic_cast. OBJPTR points to the most derrived
// object, SUBPTR points to the static base object. Both must not be NULL.
// TARGET specifies the desired target type, SUBTYPE specifies the static
// type. Both must be defined. Returns adjusted object pointer on success,
// NULL on failure. [expr.dynamic.cast]/8 says 'unambiguous public base'. This
// itself is an ambiguous statement. We choose it to mean the base must be
// separately unambiguous and public, rather than unambiguous considering only
// public bases.
void *__user_type_info::
dyncast (int boff,
const type_info &target, void *objptr,
const type_info &subtype, void *subptr) const
{
dyncast_result result;
do_dyncast (boff, contained_public,
target, objptr, subtype, subptr, result);
if (!result.target_obj)
return NULL;
if (contained_public_p (result.target2sub))
return result.target_obj;
if (contained_public_p (sub_kind (result.whole2sub & result.whole2target)))
// Found a valid cross cast
return result.target_obj;
if (contained_nonvirtual_p (result.whole2sub))
// Found an invalid cross cast, which cannot also be a down cast
return NULL;
if (result.target2sub == unknown)
result.target2sub = static_cast <const __user_type_info &> (target)
.find_public_subobj (boff, subtype,
result.target_obj, subptr);
if (contained_public_p (result.target2sub))
// Found a valid down cast
return result.target_obj;
// Must be an invalid down cast, or the cross cast wasn't bettered
return NULL;
}
// Catch cast helper. ACCESS_PATH is the access from the complete thrown
// object to this base. TARGET is the desired type we want to catch. OBJPTR
// points to this base within the throw object, it might be NULL. Fill in
// RESULT with what we find. Return true, should we determine catch must fail.
bool __user_type_info::
do_upcast (sub_kind access_path,
const type_info &target, void *objptr,
upcast_result &__restrict result) const
{
if (*this == target)
{
result.target_obj = objptr;
result.base_type = nonvirtual_base_type;
result.whole2target = access_path;
return contained_nonpublic_p (access_path);
}
return false;
}
// dynamic cast helper. ACCESS_PATH gives the access from the most derived
// object to this base. TARGET indicates the desired type we want. OBJPTR
// points to this base within the object. SUBTYPE indicates the static type
// started from and SUBPTR points to that base within the most derived object.
// Fill in RESULT with what we find. Return true if we have located an
// ambiguous match.
bool __user_type_info::
do_dyncast (int, sub_kind access_path,
const type_info &target, void *objptr,
const type_info &subtype, void *subptr,
dyncast_result &__restrict result) const
{
if (objptr == subptr && *this == subtype)
{
// The subobject we started from. Indicate how we are accessible from
// the most derived object.
result.whole2sub = access_path;
return false;
}
if (*this == target)
{
result.target_obj = objptr;
result.whole2target = access_path;
result.target2sub = not_contained;
return false;
}
return false;
}
// find_public_subobj helper. Return contained_public if we are the desired
// subtype. OBJPTR points to this base type, SUBPTR points to the desired base
// object.
__user_type_info::sub_kind __user_type_info::
do_find_public_subobj (int, const type_info &, void *objptr, void *subptr) const
{
if (subptr == objptr)
// Must be our type, as the pointers match.
return contained_public;
return not_contained;
}
// catch helper for single public inheritance types. See
// __user_type_info::do_upcast for semantics.
bool __si_type_info::
do_upcast (sub_kind access_path,
const type_info &target, void *objptr,
upcast_result &__restrict result) const
{
if (*this == target)
{
result.target_obj = objptr;
result.base_type = nonvirtual_base_type;
result.whole2target = access_path;
return contained_nonpublic_p (access_path);
}
return base.do_upcast (access_path, target, objptr, result);
}
// dynamic cast helper for single public inheritance types. See
// __user_type_info::do_dyncast for semantics. BOFF indicates how SUBTYPE
// types are inherited by TARGET types.
bool __si_type_info::
do_dyncast (int boff, sub_kind access_path,
const type_info &target, void *objptr,
const type_info &subtype, void *subptr,
dyncast_result &__restrict result) const
{
if (objptr == subptr && *this == subtype)
{
// The subobject we started from. Indicate how we are accessible from
// the most derived object.
result.whole2sub = access_path;
return false;
}
if (*this == target)
{
result.target_obj = objptr;
result.whole2target = access_path;
if (boff >= 0)
result.target2sub = ((char *)subptr - (char *)objptr) == boff
? contained_public : not_contained;
else if (boff == -2)
result.target2sub = not_contained;
return false;
}
return base.do_dyncast (boff, access_path,
target, objptr, subtype, subptr, result);
}
// find_public_subobj helper. See __user_type_info::do_find_public_subobj or
// semantics. BOFF indicates how SUBTYPE types are inherited by the original
// target object.
__user_type_info::sub_kind __si_type_info::
do_find_public_subobj (int boff, const type_info &subtype, void *objptr, void *subptr) const
{
if (subptr == objptr && subtype == *this)
return contained_public;
return base.do_find_public_subobj (boff, subtype, objptr, subptr);
}
// catch helper for multiple or non-public inheritance types. See
// __user_type_info::do_upcast for semantics.
bool __class_type_info::
do_upcast (sub_kind access_path,
const type_info &target, void *objptr,
upcast_result &__restrict result) const
{
if (*this == target)
{
result.target_obj = objptr;
result.base_type = nonvirtual_base_type;
result.whole2target = access_path;
return contained_nonpublic_p (access_path);
}
for (size_t i = n_bases; i--;)
{
upcast_result result2;
void *p = objptr;
sub_kind sub_access = access_path;
p = convert_to_base (p,
base_list[i].is_virtual,
base_list[i].offset);
if (base_list[i].is_virtual)
sub_access = sub_kind (sub_access | contained_virtual_mask);
if (base_list[i].access != PUBLIC)
sub_access = sub_kind (sub_access & ~contained_public_mask);
if (base_list[i].base->do_upcast (sub_access, target, p, result2)
&& !contained_virtual_p (result2.whole2target))
return true; // must fail
if (result2.base_type)
{
if (result2.base_type == nonvirtual_base_type
&& base_list[i].is_virtual)
result2.base_type = base_list[i].base;
if (!result.base_type)
result = result2;
else if (result.target_obj != result2.target_obj)
{
// Found an ambiguity.
result.target_obj = NULL;
result.whole2target = contained_ambig;
return true;
}
else if (result.target_obj)
{
// Ok, found real object via a virtual path.
result.whole2target
= sub_kind (result.whole2target | result2.whole2target);
}
else
{
// Dealing with a null pointer, need to check vbase
// containing each of the two choices.
if (result2.base_type == nonvirtual_base_type
|| result.base_type == nonvirtual_base_type
|| !(*result2.base_type == *result.base_type))
{
// Already ambiguous, not virtual or via different virtuals.
// Cannot match.
result.whole2target = contained_ambig;
return true;
}
result.whole2target
= sub_kind (result.whole2target | result2.whole2target);
}
}
}
return false;
}
// dynamic cast helper for non-public or multiple inheritance types. See
// __user_type_info::do_dyncast for overall semantics.
// This is a big hairy function. Although the run-time behaviour of
// dynamic_cast is simple to describe, it gives rise to some non-obvious
// behaviour. We also desire to determine as early as possible any definite
// answer we can get. Because it is unknown what the run-time ratio of
// succeeding to failing dynamic casts is, we do not know in which direction
// to bias any optimizations. To that end we make no particular effort towards
// early fail answers or early success answers. Instead we try to minimize
// work by filling in things lazily (when we know we need the information),
// and opportunisticly take early success or failure results.
bool __class_type_info::
do_dyncast (int boff, sub_kind access_path,
const type_info &target, void *objptr,
const type_info &subtype, void *subptr,
dyncast_result &__restrict result) const
{
if (objptr == subptr && *this == subtype)
{
// The subobject we started from. Indicate how we are accessible from
// the most derived object.
result.whole2sub = access_path;
return false;
}
if (*this == target)
{
result.target_obj = objptr;
result.whole2target = access_path;
if (boff >= 0)
result.target2sub = ((char *)subptr - (char *)objptr) == boff
? contained_public : not_contained;
else if (boff == -2)
result.target2sub = not_contained;
return false;
}
bool result_ambig = false;
for (size_t i = n_bases; i--;)
{
dyncast_result result2;
void *p;
sub_kind sub_access = access_path;
p = convert_to_base (objptr,
base_list[i].is_virtual,
base_list[i].offset);
if (base_list[i].is_virtual)
sub_access = sub_kind (sub_access | contained_virtual_mask);
if (base_list[i].access != PUBLIC)
sub_access = sub_kind (sub_access & ~contained_public_mask);
bool result2_ambig
= base_list[i].base->do_dyncast (boff, sub_access,
target, p, subtype, subptr, result2);
result.whole2sub = sub_kind (result.whole2sub | result2.whole2sub);
if (result2.target2sub == contained_public
|| result2.target2sub == contained_ambig)
{
result.target_obj = result2.target_obj;
result.whole2target = result2.whole2target;
result.target2sub = result2.target2sub;
// Found a downcast which can't be bettered or an ambiguous downcast
// which can't be disambiguated
return result2_ambig;
}
if (!result_ambig && !result.target_obj)
{
// Not found anything yet.
result.target_obj = result2.target_obj;
result.whole2target = result2.whole2target;
result_ambig = result2_ambig;
}
else if (result.target_obj && result.target_obj == result2.target_obj)
{
// Found at same address, must be via virtual. Pick the most
// accessible path.
result.whole2target =
sub_kind (result.whole2target | result2.whole2target);
}
else if ((result.target_obj && result2.target_obj)
|| (result_ambig && result2.target_obj)
|| (result2_ambig && result.target_obj))
{
// Found two different TARGET bases, or a valid one and a set of
// ambiguous ones, must disambiguate. See whether SUBOBJ is
// contained publicly within one of the non-ambiguous choices.
// If it is in only one, then that's the choice. If it is in
// both, then we're ambiguous and fail. If it is in neither,
// we're ambiguous, but don't yet fail as we might later find a
// third base which does contain SUBPTR.
sub_kind new_sub_kind = result2.target2sub;
sub_kind old_sub_kind = result.target2sub;
if (contained_nonvirtual_p (result.whole2sub))
{
// We already found SUBOBJ as a non-virtual base of most
// derived. Therefore if it is in either choice, it can only be
// in one of them, and we will already know.
if (old_sub_kind == unknown)
old_sub_kind = not_contained;
if (new_sub_kind == unknown)
new_sub_kind = not_contained;
}
else
{
const __user_type_info &t =
static_cast <const __user_type_info &> (target);
if (old_sub_kind >= not_contained)
;// already calculated
else if (contained_nonvirtual_p (new_sub_kind))
// Already found non-virtually inside the other choice,
// cannot be in this.
old_sub_kind = not_contained;
else
old_sub_kind = t.find_public_subobj (boff, subtype,
result.target_obj, subptr);
if (new_sub_kind >= not_contained)
;// already calculated
else if (contained_nonvirtual_p (old_sub_kind))
// Already found non-virtually inside the other choice,
// cannot be in this.
new_sub_kind = not_contained;
else
new_sub_kind = t.find_public_subobj (boff, subtype,
result2.target_obj, subptr);
}
// Neither sub_kind can be contained_ambig -- we bail out early
// when we find those.
if (contained_p (sub_kind (new_sub_kind ^ old_sub_kind)))
{
// Only on one choice, not ambiguous.
if (contained_p (new_sub_kind))
{
// Only in new.
result.target_obj = result2.target_obj;
result.whole2target = result2.whole2target;
result_ambig = false;
old_sub_kind = new_sub_kind;
}
result.target2sub = old_sub_kind;
if (result.target2sub == contained_public)
return false; // Can't be an ambiguating downcast for later discovery.
}
else if (contained_p (sub_kind (new_sub_kind & old_sub_kind)))
{
// In both.
result.target_obj = NULL;
result.target2sub = contained_ambig;
return true; // Fail.
}
else
{
// In neither publicly, ambiguous for the moment, but keep
// looking. It is possible that it was private in one or
// both and therefore we should fail, but that's just tough.
result.target_obj = NULL;
result.target2sub = not_contained;
result_ambig = true;
}
}
if (result.whole2sub == contained_private)
// We found SUBOBJ as a private non-virtual base, therefore all
// cross casts will fail. We have already found a down cast, if
// there is one.
return result_ambig;
}
return result_ambig;
}
// find_public_subobj helper for non-public or multiple inheritance types. See
// __user_type_info::do_find_public_subobj for semantics. We make use of BOFF
// to prune the base class walk.
__user_type_info::sub_kind __class_type_info::
do_find_public_subobj (int boff, const type_info &subtype, void *objptr, void *subptr) const
{
if (objptr == subptr && subtype == *this)
return contained_public;
for (size_t i = n_bases; i--;)
{
if (base_list[i].access != PUBLIC)
continue; // Not public, can't be here.
void *p;
if (base_list[i].is_virtual && boff == -3)
// Not a virtual base, so can't be here.
continue;
p = convert_to_base (objptr,
base_list[i].is_virtual,
base_list[i].offset);
sub_kind base_kind = base_list[i].base->do_find_public_subobj
(boff, subtype, p, subptr);
if (contained_p (base_kind))
{
if (base_list[i].is_virtual)
base_kind = sub_kind (base_kind | contained_virtual_mask);
return base_kind;
}
}
return not_contained;
}
#else
// new abi
namespace std {
// return true if this is a type_info for a pointer type
bool type_info::
__is_pointer_p () const
{
return false;
}
// return true if this is a type_info for a function type
bool type_info::
__is_function_p () const
{
return false;
}
// try and catch a thrown object.
bool type_info::
__do_catch (const type_info *thr_type, void **, unsigned) const
{
return *this == *thr_type;
}
// upcast from this type to the target. __class_type_info will override
bool type_info::
__do_upcast (const abi::__class_type_info *, void **) const
{
return false;
}
};
namespace {
using namespace std;
using namespace abi;
// initial part of a vtable, this structure is used with offsetof, so we don't
// have to keep alignments consistent manually.
struct vtable_prefix {
ptrdiff_t whole_object; // offset to most derived object
const __class_type_info *whole_type; // pointer to most derived type_info
const void *origin; // what a class's vptr points to
};
template <typename T>
inline const T *
adjust_pointer (const void *base, ptrdiff_t offset)
{
return reinterpret_cast <const T *>
(reinterpret_cast <const char *> (base) + offset);
}
// ADDR is a pointer to an object. Convert it to a pointer to a base,
// using OFFSET. IS_VIRTUAL is true, if we are getting a virtual base.
inline void const *
convert_to_base (void const *addr, bool is_virtual, ptrdiff_t offset)
{
if (is_virtual)
{
const void *vtable = *static_cast <const void *const *> (addr);
offset = *adjust_pointer<ptrdiff_t> (vtable, offset);
}
return adjust_pointer<void> (addr, offset);
}
// some predicate functions for __class_type_info::__sub_kind
inline bool contained_p (__class_type_info::__sub_kind access_path)
{
return access_path >= __class_type_info::__contained_mask;
}
inline bool public_p (__class_type_info::__sub_kind access_path)
{
return access_path & __class_type_info::__contained_public_mask;
}
inline bool virtual_p (__class_type_info::__sub_kind access_path)
{
return (access_path & __class_type_info::__contained_virtual_mask);
}
inline bool contained_public_p (__class_type_info::__sub_kind access_path)
{
return ((access_path & __class_type_info::__contained_public)
== __class_type_info::__contained_public);
}
inline bool contained_nonpublic_p (__class_type_info::__sub_kind access_path)
{
return ((access_path & __class_type_info::__contained_public)
== __class_type_info::__contained_mask);
}
inline bool contained_nonvirtual_p (__class_type_info::__sub_kind access_path)
{
return ((access_path & (__class_type_info::__contained_mask
| __class_type_info::__contained_virtual_mask))
== __class_type_info::__contained_mask);
}
static const __class_type_info *const nonvirtual_base_type =
static_cast <const __class_type_info *> (0) + 1;
}; // namespace
namespace __cxxabiv1
{
__class_type_info::
~__class_type_info ()
{}
__si_class_type_info::
~__si_class_type_info ()
{}
__vmi_class_type_info::
~__vmi_class_type_info ()
{}
// __upcast_result is used to hold information during traversal of a class
// heirarchy when catch matching.
struct __class_type_info::__upcast_result
{
const void *dst_ptr; // pointer to caught object
__sub_kind part2dst; // path from current base to target
int src_details; // hints about the source type heirarchy
const __class_type_info *base_type; // where we found the target,
// if in vbase the __class_type_info of vbase
// if a non-virtual base then 1
// else NULL
public:
__upcast_result (int d)
:dst_ptr (NULL), part2dst (__unknown), src_details (d), base_type (NULL)
{}
};
// __dyncast_result is used to hold information during traversal of a class
// heirarchy when dynamic casting.
struct __class_type_info::__dyncast_result
{
const void *dst_ptr; // pointer to target object or NULL
__sub_kind whole2dst; // path from most derived object to target
__sub_kind whole2src; // path from most derived object to sub object
__sub_kind dst2src; // path from target to sub object
int whole_details; // details of the whole class heirarchy
public:
__dyncast_result (int details_ = __vmi_class_type_info::__flags_unknown_mask)
:dst_ptr (NULL), whole2dst (__unknown),
whole2src (__unknown), dst2src (__unknown),
whole_details (details_)
{}
};
bool __class_type_info::
__do_catch (const type_info *thr_type,
void **thr_obj,
unsigned outer) const
{
if (*this == *thr_type)
return true;
if (outer >= 4)
// Neither `A' nor `A *'.
return false;
return thr_type->__do_upcast (this, thr_obj);
}
bool __class_type_info::
__do_upcast (const __class_type_info *dst_type,
void **obj_ptr) const
{
__upcast_result result (__vmi_class_type_info::__flags_unknown_mask);
__do_upcast (dst_type, *obj_ptr, result);
if (!contained_public_p (result.part2dst))
return false;
*obj_ptr = const_cast <void *> (result.dst_ptr);
return true;
}
inline __class_type_info::__sub_kind __class_type_info::
__find_public_src (ptrdiff_t src2dst,
const void *obj_ptr,
const __class_type_info *src_type,
const void *src_ptr) const
{
if (src2dst >= 0)
return adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
? __contained_public : __not_contained;
if (src2dst == -2)
return __not_contained;
return __do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
}
__class_type_info::__sub_kind __class_type_info::
__do_find_public_src (ptrdiff_t,
const void *obj_ptr,
const __class_type_info *,
const void *src_ptr) const
{
if (src_ptr == obj_ptr)
// Must be our type, as the pointers match.
return __contained_public;
return __not_contained;
}
__class_type_info::__sub_kind __si_class_type_info::
__do_find_public_src (ptrdiff_t src2dst,
const void *obj_ptr,
const __class_type_info *src_type,
const void *src_ptr) const
{
if (src_ptr == obj_ptr && *this == *src_type)
return __contained_public;
return __base_type->__do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
}
__class_type_info::__sub_kind __vmi_class_type_info::
__do_find_public_src (ptrdiff_t src2dst,
const void *obj_ptr,
const __class_type_info *src_type,
const void *src_ptr) const
{
if (obj_ptr == src_ptr && *this == *src_type)
return __contained_public;
for (size_t i = __base_count; i--;)
{
if (!__base_info[i].__is_public_p ())
continue; // Not public, can't be here.
const void *base = obj_ptr;
ptrdiff_t offset = __base_info[i].__offset ();
bool is_virtual = __base_info[i].__is_virtual_p ();
if (is_virtual)
{
if (src2dst == -3)
continue; // Not a virtual base, so can't be here.
}
base = convert_to_base (base, is_virtual, offset);
__sub_kind base_kind = __base_info[i].__base->__do_find_public_src
(src2dst, base, src_type, src_ptr);
if (contained_p (base_kind))
{
if (is_virtual)
base_kind = __sub_kind (base_kind | __contained_virtual_mask);
return base_kind;
}
}
return __not_contained;
}
bool __class_type_info::
__do_dyncast (ptrdiff_t,
__sub_kind access_path,
const __class_type_info *dst_type,
const void *obj_ptr,
const __class_type_info *src_type,
const void *src_ptr,
__dyncast_result &__restrict result) const
{
if (obj_ptr == src_ptr && *this == *src_type)
{
// The src object we started from. Indicate how we are accessible from
// the most derived object.
result.whole2src = access_path;
return false;
}
if (*this == *dst_type)
{
result.dst_ptr = obj_ptr;
result.whole2dst = access_path;
result.dst2src = __not_contained;
return false;
}
return false;
}
bool __si_class_type_info::
__do_dyncast (ptrdiff_t src2dst,
__sub_kind access_path,
const __class_type_info *dst_type,
const void *obj_ptr,
const __class_type_info *src_type,
const void *src_ptr,
__dyncast_result &__restrict result) const
{
if (*this == *dst_type)
{
result.dst_ptr = obj_ptr;
result.whole2dst = access_path;
if (src2dst >= 0)
result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
? __contained_public : __not_contained;
else if (src2dst == -2)
result.dst2src = __not_contained;
return false;
}
if (obj_ptr == src_ptr && *this == *src_type)
{
// The src object we started from. Indicate how we are accessible from
// the most derived object.
result.whole2src = access_path;
return false;
}
return __base_type->__do_dyncast (src2dst, access_path, dst_type, obj_ptr,
src_type, src_ptr, result);
}
// This is a big hairy function. Although the run-time behaviour of
// dynamic_cast is simple to describe, it gives rise to some non-obvious
// behaviour. We also desire to determine as early as possible any definite
// answer we can get. Because it is unknown what the run-time ratio of
// succeeding to failing dynamic casts is, we do not know in which direction
// to bias any optimizations. To that end we make no particular effort towards
// early fail answers or early success answers. Instead we try to minimize
// work by filling in things lazily (when we know we need the information),
// and opportunisticly take early success or failure results.
bool __vmi_class_type_info::
__do_dyncast (ptrdiff_t src2dst,
__sub_kind access_path,
const __class_type_info *dst_type,
const void *obj_ptr,
const __class_type_info *src_type,
const void *src_ptr,
__dyncast_result &__restrict result) const
{
if (result.whole_details & __flags_unknown_mask)
result.whole_details = __flags;
if (obj_ptr == src_ptr && *this == *src_type)
{
// The src object we started from. Indicate how we are accessible from
// the most derived object.
result.whole2src = access_path;
return false;
}
if (*this == *dst_type)
{
result.dst_ptr = obj_ptr;
result.whole2dst = access_path;
if (src2dst >= 0)
result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
? __contained_public : __not_contained;
else if (src2dst == -2)
result.dst2src = __not_contained;
return false;
}
bool result_ambig = false;
for (size_t i = __base_count; i--;)
{
__dyncast_result result2 (result.whole_details);
void const *base = obj_ptr;
__sub_kind base_access = access_path;
ptrdiff_t offset = __base_info[i].__offset ();
bool is_virtual = __base_info[i].__is_virtual_p ();
if (is_virtual)
base_access = __sub_kind (base_access | __contained_virtual_mask);
base = convert_to_base (base, is_virtual, offset);
if (!__base_info[i].__is_public_p ())
{
if (src2dst == -2 &&
!(result.whole_details
& (__non_diamond_repeat_mask | __diamond_shaped_mask)))
// The hierarchy has no duplicate bases (which might ambiguate
// things) and where we started is not a public base of what we
// want (so it cannot be a downcast). There is nothing of interest
// hiding in a non-public base.
continue;
base_access = __sub_kind (base_access & ~__contained_public_mask);
}
bool result2_ambig
= __base_info[i].__base->__do_dyncast (src2dst, base_access,
dst_type, base,
src_type, src_ptr, result2);
result.whole2src = __sub_kind (result.whole2src | result2.whole2src);
if (result2.dst2src == __contained_public
|| result2.dst2src == __contained_ambig)
{
result.dst_ptr = result2.dst_ptr;
result.whole2dst = result2.whole2dst;
result.dst2src = result2.dst2src;
// Found a downcast which can't be bettered or an ambiguous downcast
// which can't be disambiguated
return result2_ambig;
}
if (!result_ambig && !result.dst_ptr)
{
// Not found anything yet.
result.dst_ptr = result2.dst_ptr;
result.whole2dst = result2.whole2dst;
result_ambig = result2_ambig;
if (result.dst_ptr && result.whole2src != __unknown
&& !(__flags & __non_diamond_repeat_mask))
// Found dst and src and we don't have repeated bases.
return result_ambig;
}
else if (result.dst_ptr && result.dst_ptr == result2.dst_ptr)
{
// Found at same address, must be via virtual. Pick the most
// accessible path.
result.whole2dst =
__sub_kind (result.whole2dst | result2.whole2dst);
}
else if ((result.dst_ptr != 0 | result_ambig)
&& (result2.dst_ptr != 0 | result2_ambig))
{
// Found two different DST_TYPE bases, or a valid one and a set of
// ambiguous ones, must disambiguate. See whether SRC_PTR is
// contained publicly within one of the non-ambiguous choices. If it
// is in only one, then that's the choice. If it is in both, then
// we're ambiguous and fail. If it is in neither, we're ambiguous,
// but don't yet fail as we might later find a third base which does
// contain SRC_PTR.
__sub_kind new_sub_kind = result2.dst2src;
__sub_kind old_sub_kind = result.dst2src;
if (contained_p (result.whole2src)
&& (!virtual_p (result.whole2src)
|| !(result.whole_details & __diamond_shaped_mask)))
{
// We already found SRC_PTR as a base of most derived, and
// either it was non-virtual, or the whole heirarchy is
// not-diamond shaped. Therefore if it is in either choice, it
// can only be in one of them, and we will already know.
if (old_sub_kind == __unknown)
old_sub_kind = __not_contained;
if (new_sub_kind == __unknown)
new_sub_kind = __not_contained;
}
else
{
if (old_sub_kind >= __not_contained)
;// already calculated
else if (contained_p (new_sub_kind)
&& (!virtual_p (new_sub_kind)
|| !(__flags & __diamond_shaped_mask)))
// Already found inside the other choice, and it was
// non-virtual or we are not diamond shaped.
old_sub_kind = __not_contained;
else
old_sub_kind = dst_type->__find_public_src
(src2dst, result.dst_ptr, src_type, src_ptr);
if (new_sub_kind >= __not_contained)
;// already calculated
else if (contained_p (old_sub_kind)
&& (!virtual_p (old_sub_kind)
|| !(__flags & __diamond_shaped_mask)))
// Already found inside the other choice, and it was
// non-virtual or we are not diamond shaped.
new_sub_kind = __not_contained;
else
new_sub_kind = dst_type->__find_public_src
(src2dst, result2.dst_ptr, src_type, src_ptr);
}
// Neither sub_kind can be contained_ambig -- we bail out early
// when we find those.
if (contained_p (__sub_kind (new_sub_kind ^ old_sub_kind)))
{
// Only on one choice, not ambiguous.
if (contained_p (new_sub_kind))
{
// Only in new.
result.dst_ptr = result2.dst_ptr;
result.whole2dst = result2.whole2dst;
result_ambig = false;
old_sub_kind = new_sub_kind;
}
result.dst2src = old_sub_kind;
if (public_p (result.dst2src))
return false; // Can't be an ambiguating downcast for later discovery.
if (!virtual_p (result.dst2src))
return false; // Found non-virtually can't be bettered
}
else if (contained_p (__sub_kind (new_sub_kind & old_sub_kind)))
{
// In both.
result.dst_ptr = NULL;
result.dst2src = __contained_ambig;
return true; // Fail.
}
else
{
// In neither publicly, ambiguous for the moment, but keep
// looking. It is possible that it was private in one or
// both and therefore we should fail, but that's just tough.
result.dst_ptr = NULL;
result.dst2src = __not_contained;
result_ambig = true;
}
}
if (result.whole2src == __contained_private)
// We found SRC_PTR as a private non-virtual base, therefore all
// cross casts will fail. We have already found a down cast, if
// there is one.
return result_ambig;
}
return result_ambig;
}
bool __class_type_info::
__do_upcast (const __class_type_info *dst, const void *obj,
__upcast_result &__restrict result) const
{
if (*this == *dst)
{
result.dst_ptr = obj;
result.base_type = nonvirtual_base_type;
result.part2dst = __contained_public;
return true;
}
return false;
}
bool __si_class_type_info::
__do_upcast (const __class_type_info *dst, const void *obj_ptr,
__upcast_result &__restrict result) const
{
if (__class_type_info::__do_upcast (dst, obj_ptr, result))
return true;
return __base_type->__do_upcast (dst, obj_ptr, result);
}
bool __vmi_class_type_info::
__do_upcast (const __class_type_info *dst, const void *obj_ptr,
__upcast_result &__restrict result) const
{
if (__class_type_info::__do_upcast (dst, obj_ptr, result))
return true;
int src_details = result.src_details;
if (src_details & __flags_unknown_mask)
src_details = __flags;
for (size_t i = __base_count; i--;)
{
__upcast_result result2 (src_details);
const void *base = obj_ptr;
ptrdiff_t offset = __base_info[i].__offset ();
bool is_virtual = __base_info[i].__is_virtual_p ();
bool is_public = __base_info[i].__is_public_p ();
if (!is_public && !(src_details & __non_diamond_repeat_mask))
// original cannot have an ambiguous base, so skip private bases
continue;
if (base)
base = convert_to_base (base, is_virtual, offset);
if (__base_info[i].__base->__do_upcast (dst, base, result2))
{
if (result2.base_type == nonvirtual_base_type && is_virtual)
result2.base_type = __base_info[i].__base;
if (contained_p (result2.part2dst) && !is_public)
result2.part2dst = __sub_kind (result2.part2dst & ~__contained_public_mask);
if (!result.base_type)
{
result = result2;
if (!contained_p (result.part2dst))
return true; // found ambiguously
if (result.part2dst & __contained_public_mask)
{
if (!(__flags & __non_diamond_repeat_mask))
return true; // cannot have an ambiguous other base
}
else
{
if (!virtual_p (result.part2dst))
return true; // cannot have another path
if (!(__flags & __diamond_shaped_mask))
return true; // cannot have a more accessible path
}
}
else if (result.dst_ptr != result2.dst_ptr)
{
// Found an ambiguity.
result.dst_ptr = NULL;
result.part2dst = __contained_ambig;
return true;
}
else if (result.dst_ptr)
{
// Ok, found real object via a virtual path.
result.part2dst
= __sub_kind (result.part2dst | result2.part2dst);
}
else
{
// Dealing with a null pointer, need to check vbase
// containing each of the two choices.
if (result2.base_type == nonvirtual_base_type
|| result.base_type == nonvirtual_base_type
|| !(*result2.base_type == *result.base_type))
{
// Already ambiguous, not virtual or via different virtuals.
// Cannot match.
result.part2dst = __contained_ambig;
return true;
}
result.part2dst
= __sub_kind (result.part2dst | result2.part2dst);
}
}
}
return result.part2dst != __unknown;
}
// this is the external interface to the dynamic cast machinery
extern "C" void *
__dynamic_cast (const void *src_ptr, // object started from
const __class_type_info *src_type, // type of the starting object
const __class_type_info *dst_type, // desired target type
ptrdiff_t src2dst) // how src and dst are related
{
const void *vtable = *static_cast <const void *const *> (src_ptr);
const vtable_prefix *prefix =
adjust_pointer <vtable_prefix> (vtable,
-offsetof (vtable_prefix, origin));
const void *whole_ptr =
adjust_pointer <void> (src_ptr, prefix->whole_object);
const __class_type_info *whole_type = prefix->whole_type;
__class_type_info::__dyncast_result result;
whole_type->__do_dyncast (src2dst, __class_type_info::__contained_public,
dst_type, whole_ptr, src_type, src_ptr, result);
if (!result.dst_ptr)
return NULL;
if (contained_public_p (result.dst2src))
// Src is known to be a public base of dst.
return const_cast <void *> (result.dst_ptr);
if (contained_public_p (__class_type_info::__sub_kind (result.whole2src & result.whole2dst)))
// Both src and dst are known to be public bases of whole. Found a valid
// cross cast.
return const_cast <void *> (result.dst_ptr);
if (contained_nonvirtual_p (result.whole2src))
// Src is known to be a non-public nonvirtual base of whole, and not a
// base of dst. Found an invalid cross cast, which cannot also be a down
// cast
return NULL;
if (result.dst2src == __class_type_info::__unknown)
result.dst2src = dst_type->__find_public_src (src2dst, result.dst_ptr,
src_type, src_ptr);
if (contained_public_p (result.dst2src))
// Found a valid down cast
return const_cast <void *> (result.dst_ptr);
// Must be an invalid down cast, or the cross cast wasn't bettered
return NULL;
}
}; // namespace __cxxabiv1
#endif
Reference in New Issue View Git Blame Copy Permalink