1 /*
2 * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 enum {
26 // As specifed in the JVM spec
27 ITEM_Top = 0,
28 ITEM_Integer = 1,
29 ITEM_Float = 2,
30 ITEM_Double = 3,
31 ITEM_Long = 4,
32 ITEM_Null = 5,
33 ITEM_UninitializedThis = 6,
34 ITEM_Object = 7,
35 ITEM_Uninitialized = 8,
36 ITEM_Bogus = (uint)-1
37 };
38
39 class VerificationType VALUE_OBJ_CLASS_SPEC {
40 private:
41 // Least significant bits of _handle are always 0, so we use these as
42 // the indicator that the _handle is valid. Otherwise, the _data field
43 // contains encoded data (as specified below). Should the VM change
44 // and the lower bits on oops aren't 0, the assert in the constructor
45 // will catch this and we'll have to add a descriminator tag to this
46 // structure.
47 union {
48 symbolOop* _handle;
49 uintptr_t _data;
50 } _u;
51
52 enum {
53 // These rest are not found in classfiles, but used by the verifier
54 ITEM_Boolean = 9, ITEM_Byte, ITEM_Short, ITEM_Char,
55 ITEM_Long_2nd, ITEM_Double_2nd
56 };
57
58 // Enum for the _data field
59 enum {
60 // Bottom two bits determine if the type is a reference, primitive,
61 // uninitialized or a query-type.
62 TypeMask = 0x00000003,
63
64 // Topmost types encoding
65 Reference = 0x0, // _handle contains the name
66 Primitive = 0x1, // see below for primitive list
67 Uninitialized = 0x2, // 0x00ffff00 contains bci
68 TypeQuery = 0x3, // Meta-types used for category testing
69
70 // Utility flags
71 ReferenceFlag = 0x00, // For reference query types
72 Category1Flag = 0x01, // One-word values
73 Category2Flag = 0x02, // First word of a two-word value
74 Category2_2ndFlag = 0x04, // Second word of a two-word value
75
76 // special reference values
77 Null = 0x00000000, // A reference with a 0 handle is null
78
79 // Primitives categories (the second byte determines the category)
80 Category1 = (Category1Flag << 1 * BitsPerByte) | Primitive,
81 Category2 = (Category2Flag << 1 * BitsPerByte) | Primitive,
82 Category2_2nd = (Category2_2ndFlag << 1 * BitsPerByte) | Primitive,
83
84 // Primitive values (type descriminator stored in most-signifcant bytes)
85 Bogus = (ITEM_Bogus << 2 * BitsPerByte) | Category1,
86 Boolean = (ITEM_Boolean << 2 * BitsPerByte) | Category1,
87 Byte = (ITEM_Byte << 2 * BitsPerByte) | Category1,
88 Short = (ITEM_Short << 2 * BitsPerByte) | Category1,
89 Char = (ITEM_Char << 2 * BitsPerByte) | Category1,
90 Integer = (ITEM_Integer << 2 * BitsPerByte) | Category1,
91 Float = (ITEM_Float << 2 * BitsPerByte) | Category1,
92 Long = (ITEM_Long << 2 * BitsPerByte) | Category2,
93 Double = (ITEM_Double << 2 * BitsPerByte) | Category2,
94 Long_2nd = (ITEM_Long_2nd << 2 * BitsPerByte) | Category2_2nd,
95 Double_2nd = (ITEM_Double_2nd << 2 * BitsPerByte) | Category2_2nd,
96
97 // Used by Uninitialized (second and third bytes hold the bci)
98 BciMask = 0xffff << 1 * BitsPerByte,
99 BciForThis = ((u2)-1), // A bci of -1 is an Unintialized-This
100
101 // Query values
102 ReferenceQuery = (ReferenceFlag << 1 * BitsPerByte) | TypeQuery,
103 Category1Query = (Category1Flag << 1 * BitsPerByte) | TypeQuery,
104 Category2Query = (Category2Flag << 1 * BitsPerByte) | TypeQuery,
105 Category2_2ndQuery = (Category2_2ndFlag << 1 * BitsPerByte) | TypeQuery
106 };
107
108 VerificationType(uintptr_t raw_data) {
109 _u._data = raw_data;
110 }
111
112 public:
113
114 VerificationType() { *this = bogus_type(); }
115
116 // Create verification types
117 static VerificationType bogus_type() { return VerificationType(Bogus); }
118 static VerificationType null_type() { return VerificationType(Null); }
119 static VerificationType integer_type() { return VerificationType(Integer); }
120 static VerificationType float_type() { return VerificationType(Float); }
121 static VerificationType long_type() { return VerificationType(Long); }
122 static VerificationType long2_type() { return VerificationType(Long_2nd); }
123 static VerificationType double_type() { return VerificationType(Double); }
124 static VerificationType boolean_type() { return VerificationType(Boolean); }
125 static VerificationType byte_type() { return VerificationType(Byte); }
126 static VerificationType char_type() { return VerificationType(Char); }
127 static VerificationType short_type() { return VerificationType(Short); }
128 static VerificationType double2_type()
129 { return VerificationType(Double_2nd); }
130
131 // "check" types are used for queries. A "check" type is not assignable
132 // to anything, but the specified types are assignable to a "check". For
133 // example, any category1 primitive is assignable to category1_check and
134 // any reference is assignable to reference_check.
135 static VerificationType reference_check()
136 { return VerificationType(ReferenceQuery); }
137 static VerificationType category1_check()
138 { return VerificationType(Category1Query); }
139 static VerificationType category2_check()
140 { return VerificationType(Category2Query); }
141 static VerificationType category2_2nd_check()
142 { return VerificationType(Category2_2ndQuery); }
143
144 // For reference types, store the actual oop* handle
145 static VerificationType reference_type(symbolHandle sh) {
146 assert(((uintptr_t)sh.raw_value() & 0x3) == 0, "Oops must be aligned");
147 // If the above assert fails in the future because oop* isn't aligned,
148 // then this type encoding system will have to change to have a tag value
149 // to descriminate between oops and primitives.
150 return VerificationType((uintptr_t)((symbolOop*)sh.raw_value()));
151 }
152 static VerificationType reference_type(symbolOop s, TRAPS)
153 { return reference_type(symbolHandle(THREAD, s)); }
154
155 static VerificationType uninitialized_type(u2 bci)
156 { return VerificationType(bci << 1 * BitsPerByte | Uninitialized); }
157 static VerificationType uninitialized_this_type()
158 { return uninitialized_type(BciForThis); }
159
160 // Create based on u1 read from classfile
161 static VerificationType from_tag(u1 tag);
162
163 bool is_bogus() const { return (_u._data == Bogus); }
164 bool is_null() const { return (_u._data == Null); }
165 bool is_boolean() const { return (_u._data == Boolean); }
166 bool is_byte() const { return (_u._data == Byte); }
167 bool is_char() const { return (_u._data == Char); }
168 bool is_short() const { return (_u._data == Short); }
169 bool is_integer() const { return (_u._data == Integer); }
170 bool is_long() const { return (_u._data == Long); }
171 bool is_float() const { return (_u._data == Float); }
172 bool is_double() const { return (_u._data == Double); }
173 bool is_long2() const { return (_u._data == Long_2nd); }
174 bool is_double2() const { return (_u._data == Double_2nd); }
175 bool is_reference() const { return ((_u._data & TypeMask) == Reference); }
176 bool is_category1() const {
177 // This should return true for all one-word types, which are category1
178 // primitives, and references (including uninitialized refs). Though
179 // the 'query' types should technically return 'false' here, if we
180 // allow this to return true, we can perform the test using only
181 // 2 operations rather than 8 (3 masks, 3 compares and 2 logical 'ands').
182 // Since noone should call this on a query type anyway, this is ok.
183 assert(!is_check(), "Must not be a check type (wrong value returned)");
184 return ((_u._data & Category1) != Primitive);
185 // should only return false if it's a primitive, and the category1 flag
186 // is not set.
187 }
188 bool is_category2() const { return ((_u._data & Category2) == Category2); }
189 bool is_category2_2nd() const {
190 return ((_u._data & Category2_2nd) == Category2_2nd);
191 }
192 bool is_reference_check() const { return _u._data == ReferenceQuery; }
193 bool is_category1_check() const { return _u._data == Category1Query; }
194 bool is_category2_check() const { return _u._data == Category2Query; }
195 bool is_category2_2nd_check() const { return _u._data == Category2_2ndQuery; }
196 bool is_check() const { return (_u._data & TypeQuery) == TypeQuery; }
197
198 bool is_x_array(char sig) const {
199 return is_null() || (is_array() && (name()->byte_at(1) == sig));
200 }
201 bool is_int_array() const { return is_x_array('I'); }
202 bool is_byte_array() const { return is_x_array('B'); }
203 bool is_bool_array() const { return is_x_array('Z'); }
204 bool is_char_array() const { return is_x_array('C'); }
205 bool is_short_array() const { return is_x_array('S'); }
206 bool is_long_array() const { return is_x_array('J'); }
207 bool is_float_array() const { return is_x_array('F'); }
208 bool is_double_array() const { return is_x_array('D'); }
209 bool is_object_array() const { return is_x_array('L'); }
210 bool is_array_array() const { return is_x_array('['); }
211 bool is_reference_array() const
212 { return is_object_array() || is_array_array(); }
213 bool is_object() const
214 { return (is_reference() && !is_null() && name()->utf8_length() >= 1 &&
215 name()->byte_at(0) != '['); }
216 bool is_array() const
217 { return (is_reference() && !is_null() && name()->utf8_length() >= 2 &&
218 name()->byte_at(0) == '['); }
219 bool is_uninitialized() const
220 { return ((_u._data & Uninitialized) == Uninitialized); }
221 bool is_uninitialized_this() const
222 { return is_uninitialized() && bci() == BciForThis; }
223
224 VerificationType to_category2_2nd() const {
225 assert(is_category2(), "Must be a double word");
226 return VerificationType(is_long() ? Long_2nd : Double_2nd);
227 }
228
229 u2 bci() const {
230 assert(is_uninitialized(), "Must be uninitialized type");
231 return ((_u._data & BciMask) >> 1 * BitsPerByte);
232 }
233
234 symbolHandle name_handle() const {
235 assert(is_reference() && !is_null(), "Must be a non-null reference");
236 return symbolHandle(_u._handle, true);
237 }
238 symbolOop name() const {
239 assert(is_reference() && !is_null(), "Must be a non-null reference");
240 return *(_u._handle);
241 }
242
243 bool equals(const VerificationType& t) const {
244 return (_u._data == t._u._data ||
245 (is_reference() && t.is_reference() && !is_null() && !t.is_null() &&
246 name() == t.name()));
247 }
248
249 bool operator ==(const VerificationType& t) const {
250 return equals(t);
251 }
252
253 bool operator !=(const VerificationType& t) const {
254 return !equals(t);
255 }
256
257 // The whole point of this type system - check to see if one type
258 // is assignable to another. Returns true if one can assign 'from' to
259 // this.
260 bool is_assignable_from(
261 const VerificationType& from, instanceKlassHandle context, TRAPS) const {
262 if (equals(from) || is_bogus()) {
263 return true;
264 } else {
265 switch(_u._data) {
266 case Category1Query:
267 return from.is_category1();
268 case Category2Query:
269 return from.is_category2();
270 case Category2_2ndQuery:
271 return from.is_category2_2nd();
272 case ReferenceQuery:
273 return from.is_reference() || from.is_uninitialized();
274 case Boolean:
275 case Byte:
276 case Char:
277 case Short:
278 // An int can be assigned to boolean, byte, char or short values.
279 return from.is_integer();
280 default:
281 if (is_reference() && from.is_reference()) {
282 return is_reference_assignable_from(from, context, CHECK_false);
283 } else {
284 return false;
285 }
286 }
287 }
288 }
289
290 VerificationType get_component(TRAPS) const;
291
292 int dimensions() const {
293 assert(is_array(), "Must be an array");
294 int index = 0;
295 while (name()->byte_at(index++) == '[');
296 return index;
297 }
298
299 void print_on(outputStream* st) const PRODUCT_RETURN;
300
301 private:
302
303 bool is_reference_assignable_from(
304 const VerificationType&, instanceKlassHandle, TRAPS) const;
305 };