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