Thu, 27 Jan 2011 16:11:27 -0800
6990754: Use native memory and reference counting to implement SymbolTable
Summary: move symbols from permgen into C heap and reference count them
Reviewed-by: never, acorn, jmasa, stefank
1 /*
2 * Copyright (c) 2003, 2010, 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.
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23 */
25 #ifndef SHARE_VM_CLASSFILE_VERIFICATIONTYPE_HPP
26 #define SHARE_VM_CLASSFILE_VERIFICATIONTYPE_HPP
28 #include "classfile/systemDictionary.hpp"
29 #include "memory/allocation.hpp"
30 #include "oops/instanceKlass.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "oops/symbol.hpp"
33 #include "runtime/handles.hpp"
34 #include "runtime/signature.hpp"
36 enum {
37 // As specifed in the JVM spec
38 ITEM_Top = 0,
39 ITEM_Integer = 1,
40 ITEM_Float = 2,
41 ITEM_Double = 3,
42 ITEM_Long = 4,
43 ITEM_Null = 5,
44 ITEM_UninitializedThis = 6,
45 ITEM_Object = 7,
46 ITEM_Uninitialized = 8,
47 ITEM_Bogus = (uint)-1
48 };
50 class ClassVerifier;
52 class VerificationType VALUE_OBJ_CLASS_SPEC {
53 private:
54 // Least significant bits of _handle are always 0, so we use these as
55 // the indicator that the _handle is valid. Otherwise, the _data field
56 // contains encoded data (as specified below). Should the VM change
57 // and the lower bits on oops aren't 0, the assert in the constructor
58 // will catch this and we'll have to add a descriminator tag to this
59 // structure.
60 union {
61 Symbol* _sym;
62 uintptr_t _data;
63 } _u;
65 enum {
66 // These rest are not found in classfiles, but used by the verifier
67 ITEM_Boolean = 9, ITEM_Byte, ITEM_Short, ITEM_Char,
68 ITEM_Long_2nd, ITEM_Double_2nd
69 };
71 // Enum for the _data field
72 enum {
73 // Bottom two bits determine if the type is a reference, primitive,
74 // uninitialized or a query-type.
75 TypeMask = 0x00000003,
77 // Topmost types encoding
78 Reference = 0x0, // _sym contains the name
79 Primitive = 0x1, // see below for primitive list
80 Uninitialized = 0x2, // 0x00ffff00 contains bci
81 TypeQuery = 0x3, // Meta-types used for category testing
83 // Utility flags
84 ReferenceFlag = 0x00, // For reference query types
85 Category1Flag = 0x01, // One-word values
86 Category2Flag = 0x02, // First word of a two-word value
87 Category2_2ndFlag = 0x04, // Second word of a two-word value
89 // special reference values
90 Null = 0x00000000, // A reference with a 0 sym is null
92 // Primitives categories (the second byte determines the category)
93 Category1 = (Category1Flag << 1 * BitsPerByte) | Primitive,
94 Category2 = (Category2Flag << 1 * BitsPerByte) | Primitive,
95 Category2_2nd = (Category2_2ndFlag << 1 * BitsPerByte) | Primitive,
97 // Primitive values (type descriminator stored in most-signifcant bytes)
98 Bogus = (ITEM_Bogus << 2 * BitsPerByte) | Category1,
99 Boolean = (ITEM_Boolean << 2 * BitsPerByte) | Category1,
100 Byte = (ITEM_Byte << 2 * BitsPerByte) | Category1,
101 Short = (ITEM_Short << 2 * BitsPerByte) | Category1,
102 Char = (ITEM_Char << 2 * BitsPerByte) | Category1,
103 Integer = (ITEM_Integer << 2 * BitsPerByte) | Category1,
104 Float = (ITEM_Float << 2 * BitsPerByte) | Category1,
105 Long = (ITEM_Long << 2 * BitsPerByte) | Category2,
106 Double = (ITEM_Double << 2 * BitsPerByte) | Category2,
107 Long_2nd = (ITEM_Long_2nd << 2 * BitsPerByte) | Category2_2nd,
108 Double_2nd = (ITEM_Double_2nd << 2 * BitsPerByte) | Category2_2nd,
110 // Used by Uninitialized (second and third bytes hold the bci)
111 BciMask = 0xffff << 1 * BitsPerByte,
112 BciForThis = ((u2)-1), // A bci of -1 is an Unintialized-This
114 // Query values
115 ReferenceQuery = (ReferenceFlag << 1 * BitsPerByte) | TypeQuery,
116 Category1Query = (Category1Flag << 1 * BitsPerByte) | TypeQuery,
117 Category2Query = (Category2Flag << 1 * BitsPerByte) | TypeQuery,
118 Category2_2ndQuery = (Category2_2ndFlag << 1 * BitsPerByte) | TypeQuery
119 };
121 VerificationType(uintptr_t raw_data) {
122 _u._data = raw_data;
123 }
125 public:
127 VerificationType() { *this = bogus_type(); }
129 // Create verification types
130 static VerificationType bogus_type() { return VerificationType(Bogus); }
131 static VerificationType null_type() { return VerificationType(Null); }
132 static VerificationType integer_type() { return VerificationType(Integer); }
133 static VerificationType float_type() { return VerificationType(Float); }
134 static VerificationType long_type() { return VerificationType(Long); }
135 static VerificationType long2_type() { return VerificationType(Long_2nd); }
136 static VerificationType double_type() { return VerificationType(Double); }
137 static VerificationType boolean_type() { return VerificationType(Boolean); }
138 static VerificationType byte_type() { return VerificationType(Byte); }
139 static VerificationType char_type() { return VerificationType(Char); }
140 static VerificationType short_type() { return VerificationType(Short); }
141 static VerificationType double2_type()
142 { return VerificationType(Double_2nd); }
144 // "check" types are used for queries. A "check" type is not assignable
145 // to anything, but the specified types are assignable to a "check". For
146 // example, any category1 primitive is assignable to category1_check and
147 // any reference is assignable to reference_check.
148 static VerificationType reference_check()
149 { return VerificationType(ReferenceQuery); }
150 static VerificationType category1_check()
151 { return VerificationType(Category1Query); }
152 static VerificationType category2_check()
153 { return VerificationType(Category2Query); }
154 static VerificationType category2_2nd_check()
155 { return VerificationType(Category2_2ndQuery); }
157 // For reference types, store the actual Symbol
158 static VerificationType reference_type(Symbol* sh) {
159 assert(((uintptr_t)sh & 0x3) == 0, "Oops must be aligned");
160 // If the above assert fails in the future because oop* isn't aligned,
161 // then this type encoding system will have to change to have a tag value
162 // to descriminate between oops and primitives.
163 return VerificationType((uintptr_t)sh);
164 }
165 static VerificationType uninitialized_type(u2 bci)
166 { return VerificationType(bci << 1 * BitsPerByte | Uninitialized); }
167 static VerificationType uninitialized_this_type()
168 { return uninitialized_type(BciForThis); }
170 // Create based on u1 read from classfile
171 static VerificationType from_tag(u1 tag);
173 bool is_bogus() const { return (_u._data == Bogus); }
174 bool is_null() const { return (_u._data == Null); }
175 bool is_boolean() const { return (_u._data == Boolean); }
176 bool is_byte() const { return (_u._data == Byte); }
177 bool is_char() const { return (_u._data == Char); }
178 bool is_short() const { return (_u._data == Short); }
179 bool is_integer() const { return (_u._data == Integer); }
180 bool is_long() const { return (_u._data == Long); }
181 bool is_float() const { return (_u._data == Float); }
182 bool is_double() const { return (_u._data == Double); }
183 bool is_long2() const { return (_u._data == Long_2nd); }
184 bool is_double2() const { return (_u._data == Double_2nd); }
185 bool is_reference() const { return ((_u._data & TypeMask) == Reference); }
186 bool is_category1() const {
187 // This should return true for all one-word types, which are category1
188 // primitives, and references (including uninitialized refs). Though
189 // the 'query' types should technically return 'false' here, if we
190 // allow this to return true, we can perform the test using only
191 // 2 operations rather than 8 (3 masks, 3 compares and 2 logical 'ands').
192 // Since noone should call this on a query type anyway, this is ok.
193 assert(!is_check(), "Must not be a check type (wrong value returned)");
194 return ((_u._data & Category1) != Primitive);
195 // should only return false if it's a primitive, and the category1 flag
196 // is not set.
197 }
198 bool is_category2() const { return ((_u._data & Category2) == Category2); }
199 bool is_category2_2nd() const {
200 return ((_u._data & Category2_2nd) == Category2_2nd);
201 }
202 bool is_reference_check() const { return _u._data == ReferenceQuery; }
203 bool is_category1_check() const { return _u._data == Category1Query; }
204 bool is_category2_check() const { return _u._data == Category2Query; }
205 bool is_category2_2nd_check() const { return _u._data == Category2_2ndQuery; }
206 bool is_check() const { return (_u._data & TypeQuery) == TypeQuery; }
208 bool is_x_array(char sig) const {
209 return is_null() || (is_array() && (name()->byte_at(1) == sig));
210 }
211 bool is_int_array() const { return is_x_array('I'); }
212 bool is_byte_array() const { return is_x_array('B'); }
213 bool is_bool_array() const { return is_x_array('Z'); }
214 bool is_char_array() const { return is_x_array('C'); }
215 bool is_short_array() const { return is_x_array('S'); }
216 bool is_long_array() const { return is_x_array('J'); }
217 bool is_float_array() const { return is_x_array('F'); }
218 bool is_double_array() const { return is_x_array('D'); }
219 bool is_object_array() const { return is_x_array('L'); }
220 bool is_array_array() const { return is_x_array('['); }
221 bool is_reference_array() const
222 { return is_object_array() || is_array_array(); }
223 bool is_object() const
224 { return (is_reference() && !is_null() && name()->utf8_length() >= 1 &&
225 name()->byte_at(0) != '['); }
226 bool is_array() const
227 { return (is_reference() && !is_null() && name()->utf8_length() >= 2 &&
228 name()->byte_at(0) == '['); }
229 bool is_uninitialized() const
230 { return ((_u._data & Uninitialized) == Uninitialized); }
231 bool is_uninitialized_this() const
232 { return is_uninitialized() && bci() == BciForThis; }
234 VerificationType to_category2_2nd() const {
235 assert(is_category2(), "Must be a double word");
236 return VerificationType(is_long() ? Long_2nd : Double_2nd);
237 }
239 u2 bci() const {
240 assert(is_uninitialized(), "Must be uninitialized type");
241 return ((_u._data & BciMask) >> 1 * BitsPerByte);
242 }
244 Symbol* name() const {
245 assert(is_reference() && !is_null(), "Must be a non-null reference");
246 return _u._sym;
247 }
249 bool equals(const VerificationType& t) const {
250 return (_u._data == t._u._data ||
251 (is_reference() && t.is_reference() && !is_null() && !t.is_null() &&
252 name() == t.name()));
253 }
255 bool operator ==(const VerificationType& t) const {
256 return equals(t);
257 }
259 bool operator !=(const VerificationType& t) const {
260 return !equals(t);
261 }
263 // The whole point of this type system - check to see if one type
264 // is assignable to another. Returns true if one can assign 'from' to
265 // this.
266 bool is_assignable_from(
267 const VerificationType& from, ClassVerifier* context, TRAPS) const {
268 if (equals(from) || is_bogus()) {
269 return true;
270 } else {
271 switch(_u._data) {
272 case Category1Query:
273 return from.is_category1();
274 case Category2Query:
275 return from.is_category2();
276 case Category2_2ndQuery:
277 return from.is_category2_2nd();
278 case ReferenceQuery:
279 return from.is_reference() || from.is_uninitialized();
280 case Boolean:
281 case Byte:
282 case Char:
283 case Short:
284 // An int can be assigned to boolean, byte, char or short values.
285 return from.is_integer();
286 default:
287 if (is_reference() && from.is_reference()) {
288 return is_reference_assignable_from(from, context, CHECK_false);
289 } else {
290 return false;
291 }
292 }
293 }
294 }
296 VerificationType get_component(ClassVerifier* context, TRAPS) const;
298 int dimensions() const {
299 assert(is_array(), "Must be an array");
300 int index = 0;
301 while (name()->byte_at(index++) == '[');
302 return index;
303 }
305 void print_on(outputStream* st) const PRODUCT_RETURN;
307 private:
309 bool is_reference_assignable_from(
310 const VerificationType&, ClassVerifier*, TRAPS) const;
311 };
313 #endif // SHARE_VM_CLASSFILE_VERIFICATIONTYPE_HPP