1 /*
2 * Copyright 2010-2011 PathScale, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
9 *
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
15 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
16 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
21 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
23 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
24 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include "typeinfo.h"
28 #include <stdio.h>
29
30 using namespace ABI_NAMESPACE;
31
32 /**
33 * Vtable header.
34 */
35 struct vtable_header
36 {
37 /** Offset of the leaf object. */
38 ptrdiff_t leaf_offset;
39 /** Type of the object. */
40 const __class_type_info *type;
41 };
42
43 /**
44 * Simple macro that does pointer arithmetic in bytes but returns a value of
45 * the same type as the original.
46 */
47 #define ADD_TO_PTR(x, off) reinterpret_cast<__typeof__(x)>(reinterpret_cast<char*>(x) + off)
48
__do_catch(std::type_info const * ex_type,void ** exception_object,unsigned int outer) const49 bool std::type_info::__do_catch(std::type_info const *ex_type,
50 void **exception_object,
51 unsigned int outer) const
52 {
53 const type_info *type = this;
54
55 if (type == ex_type)
56 {
57 return true;
58 }
59 if (const __class_type_info *cti = dynamic_cast<const __class_type_info *>(type))
60 {
61 return ex_type->__do_upcast(cti, exception_object);
62 }
63 return false;
64 }
65
__do_catch(std::type_info const * ex_type,void ** exception_object,unsigned int outer) const66 bool __pbase_type_info::__do_catch(std::type_info const *ex_type,
67 void **exception_object,
68 unsigned int outer) const
69 {
70 if (ex_type == this)
71 {
72 return true;
73 }
74 if (!ex_type->__is_pointer_p())
75 {
76 // Can't catch a non-pointer type in a pointer catch
77 return false;
78 }
79
80 if (!(outer & 1))
81 {
82 // If the low bit is cleared on this means that we've gone
83 // through a pointer that is not const qualified.
84 return false;
85 }
86 // Clear the low bit on outer if we're not const qualified.
87 if (!(__flags & __const_mask))
88 {
89 outer &= ~1;
90 }
91
92 const __pbase_type_info *ptr_type =
93 static_cast<const __pbase_type_info*>(ex_type);
94
95 if (ptr_type->__flags & ~__flags)
96 {
97 // Handler pointer is less qualified
98 return false;
99 }
100
101 // Special case for void* handler.
102 if(*__pointee == typeid(void))
103 {
104 return true;
105 }
106
107 return __pointee->__do_catch(ptr_type->__pointee, exception_object, outer);
108 }
109
cast_to(void * obj,const struct __class_type_info * other) const110 void *__class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
111 {
112 if (this == other)
113 {
114 return obj;
115 }
116 return 0;
117 }
118
cast_to(void * obj,const struct __class_type_info * other) const119 void *__si_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
120 {
121 if (this == other)
122 {
123 return obj;
124 }
125 return __base_type->cast_to(obj, other);
126 }
__do_upcast(const __class_type_info * target,void ** thrown_object) const127 bool __si_class_type_info::__do_upcast(const __class_type_info *target,
128 void **thrown_object) const
129 {
130 if (this == target)
131 {
132 return true;
133 }
134 return __base_type->__do_upcast(target, thrown_object);
135 }
136
cast_to(void * obj,const struct __class_type_info * other) const137 void *__vmi_class_type_info::cast_to(void *obj, const struct __class_type_info *other) const
138 {
139 if (__do_upcast(other, &obj))
140 {
141 return obj;
142 }
143 return 0;
144 }
145
__do_upcast(const __class_type_info * target,void ** thrown_object) const146 bool __vmi_class_type_info::__do_upcast(const __class_type_info *target,
147 void **thrown_object) const
148 {
149 if (this == target)
150 {
151 return true;
152 }
153 for (unsigned int i=0 ; i<__base_count ; i++)
154 {
155 const __base_class_type_info *info = &__base_info[i];
156 ptrdiff_t offset = info->offset();
157 // If this is a virtual superclass, the offset is stored in the
158 // object's vtable at the offset requested; 2.9.5.6.c:
159 //
160 // 'For a non-virtual base, this is the offset in the object of the
161 // base subobject. For a virtual base, this is the offset in the
162 // virtual table of the virtual base offset for the virtual base
163 // referenced (negative).'
164
165 void *obj = *thrown_object;
166 if (info->isVirtual())
167 {
168 // Object's vtable
169 ptrdiff_t *off = *static_cast<ptrdiff_t**>(obj);
170 // Offset location in vtable
171 off = ADD_TO_PTR(off, offset);
172 offset = *off;
173 }
174 void *cast = ADD_TO_PTR(obj, offset);
175
176 if (info->__base_type == target ||
177 (info->__base_type->__do_upcast(target, &cast)))
178 {
179 *thrown_object = cast;
180 return true;
181 }
182 }
183 return 0;
184 }
185
186
187 /**
188 * ABI function used to implement the dynamic_cast<> operator. Some cases of
189 * this operator are implemented entirely in the compiler (e.g. to void*).
190 * This function implements the dynamic casts of the form dynamic_cast<T>(v).
191 * This will be translated to a call to this function with the value v as the
192 * first argument. The type id of the static type of v is the second argument
193 * and the type id of the destination type (T) is the third argument.
194 *
195 * The third argument is a hint about the compiler's guess at the correct
196 * pointer offset. If this value is negative, then -1 indicates no hint, -2
197 * that src is not a public base of dst, and -3 that src is a multiple public
198 * base type but never a virtual base type
199 */
__dynamic_cast(const void * sub,const __class_type_info * src,const __class_type_info * dst,ptrdiff_t src2dst_offset)200 extern "C" void* __dynamic_cast(const void *sub,
201 const __class_type_info *src,
202 const __class_type_info *dst,
203 ptrdiff_t src2dst_offset)
204 {
205 const char *vtable_location = *static_cast<const char * const *>(sub);
206 const vtable_header *header =
207 reinterpret_cast<const vtable_header*>(vtable_location - sizeof(vtable_header));
208 void *leaf = ADD_TO_PTR(const_cast<void *>(sub), header->leaf_offset);
209 return header->type->cast_to(leaf, dst);
210 }
211