211 lines
6.1 KiB
C++
211 lines
6.1 KiB
C++
/*
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* Copyright 2010-2011 PathScale, Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
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* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "typeinfo.h"
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#include <stdio.h>
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using namespace ABI_NAMESPACE;
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/**
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* Vtable header.
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*/
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struct vtable_header
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{
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/** Offset of the leaf object. */
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ptrdiff_t leaf_offset;
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/** Type of the object. */
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const __class_type_info *type;
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};
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/**
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* Simple macro that does pointer arithmetic in bytes but returns a value of
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* the same type as the original.
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*/
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#define ADD_TO_PTR(x, off) (__typeof__(x))(((char*)x) + off)
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bool std::type_info::__do_catch(std::type_info const *ex_type,
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void **exception_object,
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unsigned int outer) const
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{
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const type_info *type = this;
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if (type == ex_type)
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{
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return true;
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}
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if (const __class_type_info *cti = dynamic_cast<const __class_type_info *>(type))
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{
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return ex_type->__do_upcast(cti, exception_object);
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}
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return false;
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}
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bool __pbase_type_info::__do_catch(std::type_info const *ex_type,
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void **exception_object,
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unsigned int outer) const
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{
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if (ex_type == this)
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{
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return true;
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}
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if (!ex_type->__is_pointer_p())
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{
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// Can't catch a non-pointer type in a pointer catch
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return false;
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}
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if (!(outer & 1))
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{
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// If the low bit is cleared on this means that we've gone
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// through a pointer that is not const qualified.
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return false;
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}
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// Clear the low bit on outer if we're not const qualified.
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if (!(__flags & __const_mask))
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{
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outer &= ~1;
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}
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const __pbase_type_info *ptr_type =
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static_cast<const __pbase_type_info*>(ex_type);
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if (ptr_type->__flags & ~__flags)
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{
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// Handler pointer is less qualified
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return false;
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}
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// Special case for void* handler.
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if(*__pointee == typeid(void))
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{
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return true;
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}
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return __pointee->__do_catch(ptr_type->__pointee, exception_object, outer);
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}
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void *__class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
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{
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if (this == other)
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{
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return obj;
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}
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return 0;
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}
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void *__si_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
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{
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if (this == other)
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{
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return obj;
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}
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return __base_type->cast_to(obj, other);
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}
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bool __si_class_type_info::__do_upcast(const __class_type_info *target,
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void **thrown_object) const
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{
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if (this == target)
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{
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return true;
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}
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return __base_type->__do_upcast(target, thrown_object);
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}
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void *__vmi_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
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{
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if (__do_upcast(other, &obj))
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{
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return obj;
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}
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return 0;
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}
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bool __vmi_class_type_info::__do_upcast(const __class_type_info *target,
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void **thrown_object) const
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{
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if (this == target)
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{
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return true;
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}
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for (unsigned int i=0 ; i<__base_count ; i++)
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{
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const __base_class_type_info *info = &__base_info[i];
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ptrdiff_t offset = info->offset();
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// If this is a virtual superclass, the offset is stored in the
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// object's vtable at the offset requested; 2.9.5.6.c:
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//
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// 'For a non-virtual base, this is the offset in the object of the
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// base subobject. For a virtual base, this is the offset in the
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// virtual table of the virtual base offset for the virtual base
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// referenced (negative).'
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void *obj = *thrown_object;
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if (info->isVirtual())
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{
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// Object's vtable
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ptrdiff_t *off = *(ptrdiff_t**)obj;
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// Offset location in vtable
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off = ADD_TO_PTR(off, offset);
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offset = *off;
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}
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void *cast = ADD_TO_PTR(obj, offset);
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if (info->__base_type == target ||
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(info->__base_type->__do_upcast(target, &cast)))
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{
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*thrown_object = cast;
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return true;
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}
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}
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return 0;
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}
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/**
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* ABI function used to implement the dynamic_cast<> operator. Some cases of
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* this operator are implemented entirely in the compiler (e.g. to void*).
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* This function implements the dynamic casts of the form dynamic_cast<T>(v).
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* This will be translated to a call to this function with the value v as the
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* first argument. The type id of the static type of v is the second argument
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* and the type id of the destination type (T) is the third argument.
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*
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* The third argument is a hint about the compiler's guess at the correct
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* pointer offset. If this value is negative, then -1 indicates no hint, -2
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* that src is not a public base of dst, and -3 that src is a multiple public
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* base type but never a virtual base type
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*/
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extern "C" void* __dynamic_cast(const void *sub,
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const __class_type_info *src,
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const __class_type_info *dst,
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ptrdiff_t src2dst_offset)
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{
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char *vtable_location = *(char**)sub;
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const vtable_header *header =
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(const vtable_header*)(vtable_location - sizeof(vtable_header));
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void *leaf = ADD_TO_PTR((void*)sub, header->leaf_offset);
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return header->type->cast_to(leaf, dst);
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}
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