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annotate src/share/vm/ci/ciField.cpp @ 3763:e66f38dd58a9
Merge
author | ysr |
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date | Wed, 08 Jun 2011 08:39:53 -0700 |
parents | c7f3d0b4570f |
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rev | line source |
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0 | 1 /* |
2261 | 2 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "ci/ciField.hpp" | |
27 #include "ci/ciInstanceKlass.hpp" | |
28 #include "ci/ciUtilities.hpp" | |
29 #include "classfile/systemDictionary.hpp" | |
30 #include "gc_interface/collectedHeap.inline.hpp" | |
31 #include "interpreter/linkResolver.hpp" | |
32 #include "memory/universe.inline.hpp" | |
33 #include "oops/oop.inline.hpp" | |
34 #include "oops/oop.inline2.hpp" | |
35 #include "runtime/fieldDescriptor.hpp" | |
0 | 36 |
37 // ciField | |
38 // | |
39 // This class represents the result of a field lookup in the VM. | |
40 // The lookup may not succeed, in which case the information in | |
41 // the ciField will be incomplete. | |
42 | |
43 // The ciObjectFactory cannot create circular data structures in one query. | |
44 // To avoid vicious circularities, we initialize ciField::_type to NULL | |
45 // for reference types and derive it lazily from the ciField::_signature. | |
46 // Primitive types are eagerly initialized, and basic layout queries | |
47 // can succeed without initialization, using only the BasicType of the field. | |
48 | |
49 // Notes on bootstrapping and shared CI objects: A field is shared if and | |
50 // only if it is (a) non-static and (b) declared by a shared instance klass. | |
51 // This allows non-static field lists to be cached on shared types. | |
52 // Because the _type field is lazily initialized, however, there is a | |
53 // special restriction that a shared field cannot cache an unshared type. | |
54 // This puts a small performance penalty on shared fields with unshared | |
55 // types, such as StackTraceElement[] Throwable.stackTrace. | |
56 // (Throwable is shared because ClassCastException is shared, but | |
57 // StackTraceElement is not presently shared.) | |
58 | |
59 // It is not a vicious circularity for a ciField to recursively create | |
60 // the ciSymbols necessary to represent its name and signature. | |
61 // Therefore, these items are created eagerly, and the name and signature | |
62 // of a shared field are themselves shared symbols. This somewhat | |
63 // pollutes the set of shared CI objects: It grows from 50 to 93 items, | |
64 // with all of the additional 43 being uninteresting shared ciSymbols. | |
65 // This adds at most one step to the binary search, an amount which | |
66 // decreases for complex compilation tasks. | |
67 | |
68 // ------------------------------------------------------------------ | |
69 // ciField::ciField | |
70 ciField::ciField(ciInstanceKlass* klass, int index): _known_to_link_with(NULL) { | |
71 ASSERT_IN_VM; | |
72 CompilerThread *thread = CompilerThread::current(); | |
73 | |
74 assert(ciObjectFactory::is_initialized(), "not a shared field"); | |
75 | |
76 assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constan-pool"); | |
77 | |
78 _cp_index = index; | |
79 constantPoolHandle cpool(thread, klass->get_instanceKlass()->constants()); | |
80 | |
81 // Get the field's name, signature, and type. | |
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82 Symbol* name = cpool->name_ref_at(index); |
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83 _name = ciEnv::current(thread)->get_symbol(name); |
0 | 84 |
85 int nt_index = cpool->name_and_type_ref_index_at(index); | |
86 int sig_index = cpool->signature_ref_index_at(nt_index); | |
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87 Symbol* signature = cpool->symbol_at(sig_index); |
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88 _signature = ciEnv::current(thread)->get_symbol(signature); |
0 | 89 |
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90 BasicType field_type = FieldType::basic_type(signature); |
0 | 91 |
92 // If the field is a pointer type, get the klass of the | |
93 // field. | |
94 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
95 bool ignore; | |
96 // This is not really a class reference; the index always refers to the | |
97 // field's type signature, as a symbol. Linkage checks do not apply. | |
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98 _type = ciEnv::current(thread)->get_klass_by_index(cpool, sig_index, ignore, klass); |
0 | 99 } else { |
100 _type = ciType::make(field_type); | |
101 } | |
102 | |
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103 _name = (ciSymbol*)ciEnv::current(thread)->get_symbol(name); |
0 | 104 |
105 // Get the field's declared holder. | |
106 // | |
107 // Note: we actually create a ciInstanceKlass for this klass, | |
108 // even though we may not need to. | |
109 int holder_index = cpool->klass_ref_index_at(index); | |
110 bool holder_is_accessible; | |
111 ciInstanceKlass* declared_holder = | |
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112 ciEnv::current(thread)->get_klass_by_index(cpool, holder_index, |
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113 holder_is_accessible, |
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114 klass)->as_instance_klass(); |
0 | 115 |
116 // The declared holder of this field may not have been loaded. | |
117 // Bail out with partial field information. | |
118 if (!holder_is_accessible) { | |
119 // _cp_index and _type have already been set. | |
120 // The default values for _flags and _constant_value will suffice. | |
121 // We need values for _holder, _offset, and _is_constant, | |
122 _holder = declared_holder; | |
123 _offset = -1; | |
124 _is_constant = false; | |
125 return; | |
126 } | |
127 | |
128 instanceKlass* loaded_decl_holder = declared_holder->get_instanceKlass(); | |
129 | |
130 // Perform the field lookup. | |
131 fieldDescriptor field_desc; | |
132 klassOop canonical_holder = | |
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133 loaded_decl_holder->find_field(name, signature, &field_desc); |
0 | 134 if (canonical_holder == NULL) { |
135 // Field lookup failed. Will be detected by will_link. | |
136 _holder = declared_holder; | |
137 _offset = -1; | |
138 _is_constant = false; | |
139 return; | |
140 } | |
141 | |
142 assert(canonical_holder == field_desc.field_holder(), "just checking"); | |
143 initialize_from(&field_desc); | |
144 } | |
145 | |
146 ciField::ciField(fieldDescriptor *fd): _known_to_link_with(NULL) { | |
147 ASSERT_IN_VM; | |
148 | |
149 _cp_index = -1; | |
150 | |
151 // Get the field's name, signature, and type. | |
152 ciEnv* env = CURRENT_ENV; | |
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153 _name = env->get_symbol(fd->name()); |
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154 _signature = env->get_symbol(fd->signature()); |
0 | 155 |
156 BasicType field_type = fd->field_type(); | |
157 | |
158 // If the field is a pointer type, get the klass of the | |
159 // field. | |
160 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
161 _type = NULL; // must call compute_type on first access | |
162 } else { | |
163 _type = ciType::make(field_type); | |
164 } | |
165 | |
166 initialize_from(fd); | |
167 | |
168 // Either (a) it is marked shared, or else (b) we are done bootstrapping. | |
169 assert(is_shared() || ciObjectFactory::is_initialized(), | |
170 "bootstrap classes must not create & cache unshared fields"); | |
171 } | |
172 | |
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173 static bool trust_final_non_static_fields(ciInstanceKlass* holder) { |
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174 if (holder == NULL) |
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175 return false; |
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176 if (holder->name() == ciSymbol::java_lang_System()) |
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177 // Never trust strangely unstable finals: System.out, etc. |
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178 return false; |
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179 // Even if general trusting is disabled, trust system-built closures in these packages. |
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180 if (holder->is_in_package("java/lang/invoke") || holder->is_in_package("sun/invoke")) |
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181 return true; |
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182 return TrustFinalNonStaticFields; |
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183 } |
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184 |
0 | 185 void ciField::initialize_from(fieldDescriptor* fd) { |
186 // Get the flags, offset, and canonical holder of the field. | |
187 _flags = ciFlags(fd->access_flags()); | |
188 _offset = fd->offset(); | |
189 _holder = CURRENT_ENV->get_object(fd->field_holder())->as_instance_klass(); | |
190 | |
191 // Check to see if the field is constant. | |
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192 if (_holder->is_initialized() && this->is_final()) { |
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193 if (!this->is_static()) { |
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194 // A field can be constant if it's a final static field or if |
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195 // it's a final non-static field of a trusted class (classes in |
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196 // java.lang.invoke and sun.invoke packages and subpackages). |
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197 if (trust_final_non_static_fields(_holder)) { |
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198 _is_constant = true; |
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199 return; |
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200 } |
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201 _is_constant = false; |
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202 return; |
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203 } |
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204 |
0 | 205 // This field just may be constant. The only cases where it will |
206 // not be constant are: | |
207 // | |
208 // 1. The field holds a non-perm-space oop. The field is, strictly | |
209 // speaking, constant but we cannot embed non-perm-space oops into | |
210 // generated code. For the time being we need to consider the | |
211 // field to be not constant. | |
212 // 2. The field is a *special* static&final field whose value | |
213 // may change. The three examples are java.lang.System.in, | |
214 // java.lang.System.out, and java.lang.System.err. | |
215 | |
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216 KlassHandle k = _holder->get_klassOop(); |
1142 | 217 assert( SystemDictionary::System_klass() != NULL, "Check once per vm"); |
2261 | 218 if( k() == SystemDictionary::System_klass() ) { |
0 | 219 // Check offsets for case 2: System.in, System.out, or System.err |
220 if( _offset == java_lang_System::in_offset_in_bytes() || | |
221 _offset == java_lang_System::out_offset_in_bytes() || | |
222 _offset == java_lang_System::err_offset_in_bytes() ) { | |
223 _is_constant = false; | |
224 return; | |
225 } | |
226 } | |
227 | |
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228 Handle mirror = k->java_mirror(); |
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229 |
0 | 230 _is_constant = true; |
231 switch(type()->basic_type()) { | |
232 case T_BYTE: | |
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233 _constant_value = ciConstant(type()->basic_type(), mirror->byte_field(_offset)); |
0 | 234 break; |
235 case T_CHAR: | |
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236 _constant_value = ciConstant(type()->basic_type(), mirror->char_field(_offset)); |
0 | 237 break; |
238 case T_SHORT: | |
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239 _constant_value = ciConstant(type()->basic_type(), mirror->short_field(_offset)); |
0 | 240 break; |
241 case T_BOOLEAN: | |
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242 _constant_value = ciConstant(type()->basic_type(), mirror->bool_field(_offset)); |
0 | 243 break; |
244 case T_INT: | |
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245 _constant_value = ciConstant(type()->basic_type(), mirror->int_field(_offset)); |
0 | 246 break; |
247 case T_FLOAT: | |
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248 _constant_value = ciConstant(mirror->float_field(_offset)); |
0 | 249 break; |
250 case T_DOUBLE: | |
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251 _constant_value = ciConstant(mirror->double_field(_offset)); |
0 | 252 break; |
253 case T_LONG: | |
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254 _constant_value = ciConstant(mirror->long_field(_offset)); |
0 | 255 break; |
256 case T_OBJECT: | |
257 case T_ARRAY: | |
258 { | |
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259 oop o = mirror->obj_field(_offset); |
0 | 260 |
261 // A field will be "constant" if it is known always to be | |
262 // a non-null reference to an instance of a particular class, | |
263 // or to a particular array. This can happen even if the instance | |
264 // or array is not perm. In such a case, an "unloaded" ciArray | |
265 // or ciInstance is created. The compiler may be able to use | |
266 // information about the object's class (which is exact) or length. | |
267 | |
268 if (o == NULL) { | |
269 _constant_value = ciConstant(type()->basic_type(), ciNullObject::make()); | |
270 } else { | |
271 _constant_value = ciConstant(type()->basic_type(), CURRENT_ENV->get_object(o)); | |
272 assert(_constant_value.as_object() == CURRENT_ENV->get_object(o), "check interning"); | |
273 } | |
274 } | |
275 } | |
276 } else { | |
277 _is_constant = false; | |
278 } | |
279 } | |
280 | |
281 // ------------------------------------------------------------------ | |
282 // ciField::compute_type | |
283 // | |
284 // Lazily compute the type, if it is an instance klass. | |
285 ciType* ciField::compute_type() { | |
286 GUARDED_VM_ENTRY(return compute_type_impl();) | |
287 } | |
288 | |
289 ciType* ciField::compute_type_impl() { | |
290 ciKlass* type = CURRENT_ENV->get_klass_by_name_impl(_holder, _signature, false); | |
291 if (!type->is_primitive_type() && is_shared()) { | |
292 // We must not cache a pointer to an unshared type, in a shared field. | |
293 bool type_is_also_shared = false; | |
294 if (type->is_type_array_klass()) { | |
295 type_is_also_shared = true; // int[] etc. are explicitly bootstrapped | |
296 } else if (type->is_instance_klass()) { | |
297 type_is_also_shared = type->as_instance_klass()->is_shared(); | |
298 } else { | |
299 // Currently there is no 'shared' query for array types. | |
300 type_is_also_shared = !ciObjectFactory::is_initialized(); | |
301 } | |
302 if (!type_is_also_shared) | |
303 return type; // Bummer. | |
304 } | |
305 _type = type; | |
306 return type; | |
307 } | |
308 | |
309 | |
310 // ------------------------------------------------------------------ | |
311 // ciField::will_link | |
312 // | |
313 // Can a specific access to this field be made without causing | |
314 // link errors? | |
315 bool ciField::will_link(ciInstanceKlass* accessing_klass, | |
316 Bytecodes::Code bc) { | |
317 VM_ENTRY_MARK; | |
318 if (_offset == -1) { | |
319 // at creation we couldn't link to our holder so we need to | |
320 // maintain that stance, otherwise there's no safe way to use this | |
321 // ciField. | |
322 return false; | |
323 } | |
324 | |
325 if (_known_to_link_with == accessing_klass) { | |
326 return true; | |
327 } | |
328 | |
329 FieldAccessInfo result; | |
330 constantPoolHandle c_pool(THREAD, | |
331 accessing_klass->get_instanceKlass()->constants()); | |
332 LinkResolver::resolve_field(result, c_pool, _cp_index, | |
333 Bytecodes::java_code(bc), | |
334 true, false, KILL_COMPILE_ON_FATAL_(false)); | |
335 | |
336 // update the hit-cache, unless there is a problem with memory scoping: | |
337 if (accessing_klass->is_shared() || !is_shared()) | |
338 _known_to_link_with = accessing_klass; | |
339 | |
340 return true; | |
341 } | |
342 | |
343 // ------------------------------------------------------------------ | |
344 // ciField::print | |
345 void ciField::print() { | |
346 tty->print("<ciField "); | |
347 _holder->print_name(); | |
348 tty->print("."); | |
349 _name->print_symbol(); | |
350 tty->print(" offset=%d type=", _offset); | |
351 if (_type != NULL) _type->print_name(); | |
352 else tty->print("(reference)"); | |
353 tty->print(" is_constant=%s", bool_to_str(_is_constant)); | |
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354 if (_is_constant && is_static()) { |
0 | 355 tty->print(" constant_value="); |
356 _constant_value.print(); | |
357 } | |
358 tty->print(">"); | |
359 } | |
360 | |
361 // ------------------------------------------------------------------ | |
362 // ciField::print_name_on | |
363 // | |
364 // Print the name of this field | |
365 void ciField::print_name_on(outputStream* st) { | |
366 name()->print_symbol_on(st); | |
367 } |