0,0 → 1,97 |
// Copyright (C) 1994-2015 Free Software Foundation, Inc. |
// |
// This file is part of GCC. |
// |
// GCC 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 3, or (at your option) |
// any later version. |
|
// GCC 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. |
|
// Under Section 7 of GPL version 3, you are granted additional |
// permissions described in the GCC Runtime Library Exception, version |
// 3.1, as published by the Free Software Foundation. |
|
// You should have received a copy of the GNU General Public License and |
// a copy of the GCC Runtime Library Exception along with this program; |
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
// <http://www.gnu.org/licenses/>. |
|
#include "tinfo.h" |
|
namespace __cxxabiv1 { |
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// this is the external interface to the dynamic cast machinery |
/* sub: source address to be adjusted; nonnull, and since the |
* source object is polymorphic, *(void**)sub is a virtual pointer. |
* src: static type of the source object. |
* dst: destination type (the "T" in "dynamic_cast<T>(v)"). |
* src2dst_offset: a static hint about the location of the |
* source subobject with respect to the complete object; |
* special negative values are: |
* -1: no hint |
* -2: src is not a public base of dst |
* -3: src is a multiple public base type but never a |
* virtual base type |
* otherwise, the src type is a unique public nonvirtual |
* base type of dst at offset src2dst_offset from the |
* origin of dst. */ |
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; |
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// If the whole object vptr doesn't refer to the whole object type, we're |
// in the middle of constructing a primary base, and src is a separate |
// base. This has undefined behavior and we can't find anything outside |
// of the base we're actually constructing, so fail now rather than |
// segfault later trying to use a vbase offset that doesn't exist. |
const void *whole_vtable = *static_cast <const void *const *> (whole_ptr); |
const vtable_prefix *whole_prefix = |
adjust_pointer <vtable_prefix> (whole_vtable, |
-offsetof (vtable_prefix, origin)); |
if (whole_prefix->whole_type != whole_type) |
return NULL; |
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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; |
} |
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} |