Mercurial > hg > graal-compiler
annotate src/share/vm/ci/ciField.cpp @ 1766:02f0a9b6f654
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Reviewed-by: kvn
author | never |
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date | Mon, 30 Aug 2010 17:27:35 -0700 |
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0 | 1 /* |
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2 * Copyright (c) 1999, 2009, 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 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_ciField.cpp.incl" | |
27 | |
28 // ciField | |
29 // | |
30 // This class represents the result of a field lookup in the VM. | |
31 // The lookup may not succeed, in which case the information in | |
32 // the ciField will be incomplete. | |
33 | |
34 // The ciObjectFactory cannot create circular data structures in one query. | |
35 // To avoid vicious circularities, we initialize ciField::_type to NULL | |
36 // for reference types and derive it lazily from the ciField::_signature. | |
37 // Primitive types are eagerly initialized, and basic layout queries | |
38 // can succeed without initialization, using only the BasicType of the field. | |
39 | |
40 // Notes on bootstrapping and shared CI objects: A field is shared if and | |
41 // only if it is (a) non-static and (b) declared by a shared instance klass. | |
42 // This allows non-static field lists to be cached on shared types. | |
43 // Because the _type field is lazily initialized, however, there is a | |
44 // special restriction that a shared field cannot cache an unshared type. | |
45 // This puts a small performance penalty on shared fields with unshared | |
46 // types, such as StackTraceElement[] Throwable.stackTrace. | |
47 // (Throwable is shared because ClassCastException is shared, but | |
48 // StackTraceElement is not presently shared.) | |
49 | |
50 // It is not a vicious circularity for a ciField to recursively create | |
51 // the ciSymbols necessary to represent its name and signature. | |
52 // Therefore, these items are created eagerly, and the name and signature | |
53 // of a shared field are themselves shared symbols. This somewhat | |
54 // pollutes the set of shared CI objects: It grows from 50 to 93 items, | |
55 // with all of the additional 43 being uninteresting shared ciSymbols. | |
56 // This adds at most one step to the binary search, an amount which | |
57 // decreases for complex compilation tasks. | |
58 | |
59 // ------------------------------------------------------------------ | |
60 // ciField::ciField | |
61 ciField::ciField(ciInstanceKlass* klass, int index): _known_to_link_with(NULL) { | |
62 ASSERT_IN_VM; | |
63 CompilerThread *thread = CompilerThread::current(); | |
64 | |
65 assert(ciObjectFactory::is_initialized(), "not a shared field"); | |
66 | |
67 assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constan-pool"); | |
68 | |
69 _cp_index = index; | |
70 constantPoolHandle cpool(thread, klass->get_instanceKlass()->constants()); | |
71 | |
72 // Get the field's name, signature, and type. | |
73 symbolHandle name (thread, cpool->name_ref_at(index)); | |
74 _name = ciEnv::current(thread)->get_object(name())->as_symbol(); | |
75 | |
76 int nt_index = cpool->name_and_type_ref_index_at(index); | |
77 int sig_index = cpool->signature_ref_index_at(nt_index); | |
78 symbolHandle signature (thread, cpool->symbol_at(sig_index)); | |
79 _signature = ciEnv::current(thread)->get_object(signature())->as_symbol(); | |
80 | |
81 BasicType field_type = FieldType::basic_type(signature()); | |
82 | |
83 // If the field is a pointer type, get the klass of the | |
84 // field. | |
85 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
86 bool ignore; | |
87 // This is not really a class reference; the index always refers to the | |
88 // field's type signature, as a symbol. Linkage checks do not apply. | |
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89 _type = ciEnv::current(thread)->get_klass_by_index(cpool, sig_index, ignore, klass); |
0 | 90 } else { |
91 _type = ciType::make(field_type); | |
92 } | |
93 | |
94 _name = (ciSymbol*)ciEnv::current(thread)->get_object(name()); | |
95 | |
96 // Get the field's declared holder. | |
97 // | |
98 // Note: we actually create a ciInstanceKlass for this klass, | |
99 // even though we may not need to. | |
100 int holder_index = cpool->klass_ref_index_at(index); | |
101 bool holder_is_accessible; | |
102 ciInstanceKlass* declared_holder = | |
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103 ciEnv::current(thread)->get_klass_by_index(cpool, holder_index, |
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104 holder_is_accessible, |
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105 klass)->as_instance_klass(); |
0 | 106 |
107 // The declared holder of this field may not have been loaded. | |
108 // Bail out with partial field information. | |
109 if (!holder_is_accessible) { | |
110 // _cp_index and _type have already been set. | |
111 // The default values for _flags and _constant_value will suffice. | |
112 // We need values for _holder, _offset, and _is_constant, | |
113 _holder = declared_holder; | |
114 _offset = -1; | |
115 _is_constant = false; | |
116 return; | |
117 } | |
118 | |
119 instanceKlass* loaded_decl_holder = declared_holder->get_instanceKlass(); | |
120 | |
121 // Perform the field lookup. | |
122 fieldDescriptor field_desc; | |
123 klassOop canonical_holder = | |
124 loaded_decl_holder->find_field(name(), signature(), &field_desc); | |
125 if (canonical_holder == NULL) { | |
126 // Field lookup failed. Will be detected by will_link. | |
127 _holder = declared_holder; | |
128 _offset = -1; | |
129 _is_constant = false; | |
130 return; | |
131 } | |
132 | |
133 assert(canonical_holder == field_desc.field_holder(), "just checking"); | |
134 initialize_from(&field_desc); | |
135 } | |
136 | |
137 ciField::ciField(fieldDescriptor *fd): _known_to_link_with(NULL) { | |
138 ASSERT_IN_VM; | |
139 | |
140 _cp_index = -1; | |
141 | |
142 // Get the field's name, signature, and type. | |
143 ciEnv* env = CURRENT_ENV; | |
144 _name = env->get_object(fd->name())->as_symbol(); | |
145 _signature = env->get_object(fd->signature())->as_symbol(); | |
146 | |
147 BasicType field_type = fd->field_type(); | |
148 | |
149 // If the field is a pointer type, get the klass of the | |
150 // field. | |
151 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
152 _type = NULL; // must call compute_type on first access | |
153 } else { | |
154 _type = ciType::make(field_type); | |
155 } | |
156 | |
157 initialize_from(fd); | |
158 | |
159 // Either (a) it is marked shared, or else (b) we are done bootstrapping. | |
160 assert(is_shared() || ciObjectFactory::is_initialized(), | |
161 "bootstrap classes must not create & cache unshared fields"); | |
162 } | |
163 | |
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164 static bool trust_final_non_static_fields(ciInstanceKlass* holder) { |
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165 if (holder == NULL) |
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166 return false; |
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167 if (holder->name() == ciSymbol::java_lang_System()) |
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168 // Never trust strangely unstable finals: System.out, etc. |
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169 return false; |
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170 // Even if general trusting is disabled, trust system-built closures in these packages. |
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171 if (holder->is_in_package("java/dyn") || holder->is_in_package("sun/dyn")) |
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172 return true; |
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173 return TrustFinalNonStaticFields; |
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174 } |
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175 |
0 | 176 void ciField::initialize_from(fieldDescriptor* fd) { |
177 // Get the flags, offset, and canonical holder of the field. | |
178 _flags = ciFlags(fd->access_flags()); | |
179 _offset = fd->offset(); | |
180 _holder = CURRENT_ENV->get_object(fd->field_holder())->as_instance_klass(); | |
181 | |
182 // Check to see if the field is constant. | |
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183 if (_holder->is_initialized() && this->is_final()) { |
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184 if (!this->is_static()) { |
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185 // A field can be constant if it's a final static field or if it's |
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186 // a final non-static field of a trusted class ({java,sun}.dyn). |
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187 if (trust_final_non_static_fields(_holder)) { |
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188 _is_constant = true; |
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189 return; |
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190 } |
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191 _is_constant = false; |
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192 return; |
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193 } |
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194 |
0 | 195 // This field just may be constant. The only cases where it will |
196 // not be constant are: | |
197 // | |
198 // 1. The field holds a non-perm-space oop. The field is, strictly | |
199 // speaking, constant but we cannot embed non-perm-space oops into | |
200 // generated code. For the time being we need to consider the | |
201 // field to be not constant. | |
202 // 2. The field is a *special* static&final field whose value | |
203 // may change. The three examples are java.lang.System.in, | |
204 // java.lang.System.out, and java.lang.System.err. | |
205 | |
206 klassOop k = _holder->get_klassOop(); | |
1142 | 207 assert( SystemDictionary::System_klass() != NULL, "Check once per vm"); |
208 if( k == SystemDictionary::System_klass() ) { | |
0 | 209 // Check offsets for case 2: System.in, System.out, or System.err |
210 if( _offset == java_lang_System::in_offset_in_bytes() || | |
211 _offset == java_lang_System::out_offset_in_bytes() || | |
212 _offset == java_lang_System::err_offset_in_bytes() ) { | |
213 _is_constant = false; | |
214 return; | |
215 } | |
216 } | |
217 | |
218 _is_constant = true; | |
219 switch(type()->basic_type()) { | |
220 case T_BYTE: | |
221 _constant_value = ciConstant(type()->basic_type(), k->byte_field(_offset)); | |
222 break; | |
223 case T_CHAR: | |
224 _constant_value = ciConstant(type()->basic_type(), k->char_field(_offset)); | |
225 break; | |
226 case T_SHORT: | |
227 _constant_value = ciConstant(type()->basic_type(), k->short_field(_offset)); | |
228 break; | |
229 case T_BOOLEAN: | |
230 _constant_value = ciConstant(type()->basic_type(), k->bool_field(_offset)); | |
231 break; | |
232 case T_INT: | |
233 _constant_value = ciConstant(type()->basic_type(), k->int_field(_offset)); | |
234 break; | |
235 case T_FLOAT: | |
236 _constant_value = ciConstant(k->float_field(_offset)); | |
237 break; | |
238 case T_DOUBLE: | |
239 _constant_value = ciConstant(k->double_field(_offset)); | |
240 break; | |
241 case T_LONG: | |
242 _constant_value = ciConstant(k->long_field(_offset)); | |
243 break; | |
244 case T_OBJECT: | |
245 case T_ARRAY: | |
246 { | |
247 oop o = k->obj_field(_offset); | |
248 | |
249 // A field will be "constant" if it is known always to be | |
250 // a non-null reference to an instance of a particular class, | |
251 // or to a particular array. This can happen even if the instance | |
252 // or array is not perm. In such a case, an "unloaded" ciArray | |
253 // or ciInstance is created. The compiler may be able to use | |
254 // information about the object's class (which is exact) or length. | |
255 | |
256 if (o == NULL) { | |
257 _constant_value = ciConstant(type()->basic_type(), ciNullObject::make()); | |
258 } else { | |
259 _constant_value = ciConstant(type()->basic_type(), CURRENT_ENV->get_object(o)); | |
260 assert(_constant_value.as_object() == CURRENT_ENV->get_object(o), "check interning"); | |
261 } | |
262 } | |
263 } | |
264 } else { | |
265 _is_constant = false; | |
266 } | |
267 } | |
268 | |
269 // ------------------------------------------------------------------ | |
270 // ciField::compute_type | |
271 // | |
272 // Lazily compute the type, if it is an instance klass. | |
273 ciType* ciField::compute_type() { | |
274 GUARDED_VM_ENTRY(return compute_type_impl();) | |
275 } | |
276 | |
277 ciType* ciField::compute_type_impl() { | |
278 ciKlass* type = CURRENT_ENV->get_klass_by_name_impl(_holder, _signature, false); | |
279 if (!type->is_primitive_type() && is_shared()) { | |
280 // We must not cache a pointer to an unshared type, in a shared field. | |
281 bool type_is_also_shared = false; | |
282 if (type->is_type_array_klass()) { | |
283 type_is_also_shared = true; // int[] etc. are explicitly bootstrapped | |
284 } else if (type->is_instance_klass()) { | |
285 type_is_also_shared = type->as_instance_klass()->is_shared(); | |
286 } else { | |
287 // Currently there is no 'shared' query for array types. | |
288 type_is_also_shared = !ciObjectFactory::is_initialized(); | |
289 } | |
290 if (!type_is_also_shared) | |
291 return type; // Bummer. | |
292 } | |
293 _type = type; | |
294 return type; | |
295 } | |
296 | |
297 | |
298 // ------------------------------------------------------------------ | |
299 // ciField::will_link | |
300 // | |
301 // Can a specific access to this field be made without causing | |
302 // link errors? | |
303 bool ciField::will_link(ciInstanceKlass* accessing_klass, | |
304 Bytecodes::Code bc) { | |
305 VM_ENTRY_MARK; | |
306 if (_offset == -1) { | |
307 // at creation we couldn't link to our holder so we need to | |
308 // maintain that stance, otherwise there's no safe way to use this | |
309 // ciField. | |
310 return false; | |
311 } | |
312 | |
313 if (_known_to_link_with == accessing_klass) { | |
314 return true; | |
315 } | |
316 | |
317 FieldAccessInfo result; | |
318 constantPoolHandle c_pool(THREAD, | |
319 accessing_klass->get_instanceKlass()->constants()); | |
320 LinkResolver::resolve_field(result, c_pool, _cp_index, | |
321 Bytecodes::java_code(bc), | |
322 true, false, KILL_COMPILE_ON_FATAL_(false)); | |
323 | |
324 // update the hit-cache, unless there is a problem with memory scoping: | |
325 if (accessing_klass->is_shared() || !is_shared()) | |
326 _known_to_link_with = accessing_klass; | |
327 | |
328 return true; | |
329 } | |
330 | |
331 // ------------------------------------------------------------------ | |
332 // ciField::print | |
333 void ciField::print() { | |
334 tty->print("<ciField "); | |
335 _holder->print_name(); | |
336 tty->print("."); | |
337 _name->print_symbol(); | |
338 tty->print(" offset=%d type=", _offset); | |
339 if (_type != NULL) _type->print_name(); | |
340 else tty->print("(reference)"); | |
341 tty->print(" is_constant=%s", bool_to_str(_is_constant)); | |
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342 if (_is_constant && is_static()) { |
0 | 343 tty->print(" constant_value="); |
344 _constant_value.print(); | |
345 } | |
346 tty->print(">"); | |
347 } | |
348 | |
349 // ------------------------------------------------------------------ | |
350 // ciField::print_name_on | |
351 // | |
352 // Print the name of this field | |
353 void ciField::print_name_on(outputStream* st) { | |
354 name()->print_symbol_on(st); | |
355 } |