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src/hotspot/share/ci/ciField.cpp

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 54 // This allows non-static field lists to be cached on shared types.
 55 // Because the _type field is lazily initialized, however, there is a
 56 // special restriction that a shared field cannot cache an unshared type.
 57 // This puts a small performance penalty on shared fields with unshared
 58 // types, such as StackTraceElement[] Throwable.stackTrace.
 59 // (Throwable is shared because ClassCastException is shared, but
 60 // StackTraceElement is not presently shared.)
 61 
 62 // It is not a vicious circularity for a ciField to recursively create
 63 // the ciSymbols necessary to represent its name and signature.
 64 // Therefore, these items are created eagerly, and the name and signature
 65 // of a shared field are themselves shared symbols.  This somewhat
 66 // pollutes the set of shared CI objects:  It grows from 50 to 93 items,
 67 // with all of the additional 43 being uninteresting shared ciSymbols.
 68 // This adds at most one step to the binary search, an amount which
 69 // decreases for complex compilation tasks.
 70 
 71 // ------------------------------------------------------------------
 72 // ciField::ciField
 73 ciField::ciField(ciInstanceKlass* klass, int index) :
 74     _known_to_link_with_put(NULL), _known_to_link_with_get(NULL) {
 75   ASSERT_IN_VM;
 76   CompilerThread *THREAD = CompilerThread::current();
 77 
 78   assert(ciObjectFactory::is_initialized(), "not a shared field");
 79 
 80   assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constant-pool");
 81 
 82   constantPoolHandle cpool(THREAD, klass->get_instanceKlass()->constants());
 83 
 84   // Get the field's name, signature, and type.
 85   Symbol* name  = cpool->name_ref_at(index);
 86   _name = ciEnv::current(THREAD)->get_symbol(name);
 87 
 88   int nt_index = cpool->name_and_type_ref_index_at(index);
 89   int sig_index = cpool->signature_ref_index_at(nt_index);
 90   Symbol* signature = cpool->symbol_at(sig_index);
 91   _signature = ciEnv::current(THREAD)->get_symbol(signature);
 92 
 93   BasicType field_type = Signature::basic_type(signature);
 94 
 95   // If the field is a pointer type, get the klass of the
 96   // field.
 97   if (is_reference_type(field_type)) {
 98     bool ignore;
 99     // This is not really a class reference; the index always refers to the
100     // field's type signature, as a symbol.  Linkage checks do not apply.
101     _type = ciEnv::current(THREAD)->get_klass_by_index(cpool, sig_index, ignore, klass);
102   } else {
103     _type = ciType::make(field_type);
104   }
105 
106   _name = (ciSymbol*)ciEnv::current(THREAD)->get_symbol(name);
107 



108   // Get the field's declared holder.
109   //
110   // Note: we actually create a ciInstanceKlass for this klass,
111   // even though we may not need to.
112   int holder_index = cpool->klass_ref_index_at(index);
113   bool holder_is_accessible;
114 
115   ciKlass* generic_declared_holder = ciEnv::current(THREAD)->get_klass_by_index(cpool, holder_index,
116                                                                                 holder_is_accessible,
117                                                                                 klass);
118 
119   if (generic_declared_holder->is_array_klass()) {
120     // If the declared holder of the field is an array class, assume that
121     // the canonical holder of that field is java.lang.Object. Arrays
122     // do not have fields; java.lang.Object is the only supertype of an
123     // array type that can declare fields and is therefore the canonical
124     // holder of the array type.
125     //
126     // Furthermore, the compilers assume that java.lang.Object does not
127     // have any fields. Therefore, the field is not looked up. Instead,

199   _name = env->get_symbol(fd->name());
200   _signature = env->get_symbol(fd->signature());
201 
202   BasicType field_type = fd->field_type();
203 
204   // If the field is a pointer type, get the klass of the
205   // field.
206   if (is_reference_type(field_type)) {
207     _type = NULL;  // must call compute_type on first access
208   } else {
209     _type = ciType::make(field_type);
210   }
211 
212   initialize_from(fd);
213 
214   // Either (a) it is marked shared, or else (b) we are done bootstrapping.
215   assert(is_shared() || ciObjectFactory::is_initialized(),
216          "bootstrap classes must not create & cache unshared fields");
217 }
218 
























219 static bool trust_final_non_static_fields(ciInstanceKlass* holder) {
220   if (holder == NULL)
221     return false;
222   if (holder->name() == ciSymbols::java_lang_System())
223     // Never trust strangely unstable finals:  System.out, etc.
224     return false;
225   // Even if general trusting is disabled, trust system-built closures in these packages.
226   if (holder->is_in_package("java/lang/invoke") || holder->is_in_package("sun/invoke") ||
227       holder->is_in_package("java/lang/reflect") || holder->is_in_package("jdk/internal/reflect") ||
228       holder->is_in_package("jdk/internal/foreign") || holder->is_in_package("jdk/incubator/foreign") ||
229       holder->is_in_package("jdk/internal/vm/vector") || holder->is_in_package("jdk/incubator/vector") ||
230       holder->is_in_package("java/lang"))
231     return true;
232   // Trust hidden classes. They are created via Lookup.defineHiddenClass and
233   // can't be serialized, so there is no hacking of finals going on with them.
234   if (holder->is_hidden())
235     return true;



236   // Trust final fields in all boxed classes
237   if (holder->is_box_klass())
238     return true;
239   // Trust final fields in records
240   if (holder->is_record())
241     return true;
242   // Trust final fields in String
243   if (holder->name() == ciSymbols::java_lang_String())
244     return true;
245   // Trust Atomic*FieldUpdaters: they are very important for performance, and make up one
246   // more reason not to use Unsafe, if their final fields are trusted. See more in JDK-8140483.
247   if (holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicIntegerFieldUpdater_Impl() ||
248       holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicLongFieldUpdater_CASUpdater() ||
249       holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicLongFieldUpdater_LockedUpdater() ||
250       holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicReferenceFieldUpdater_Impl()) {
251     return true;
252   }
253   return TrustFinalNonStaticFields;
254 }
255 
256 void ciField::initialize_from(fieldDescriptor* fd) {
257   // Get the flags, offset, and canonical holder of the field.
258   _flags = ciFlags(fd->access_flags());
259   _offset = fd->offset();
260   Klass* field_holder = fd->field_holder();
261   assert(field_holder != NULL, "null field_holder");
262   _holder = CURRENT_ENV->get_instance_klass(field_holder);


263 
264   // Check to see if the field is constant.
265   Klass* k = _holder->get_Klass();
266   bool is_stable_field = FoldStableValues && is_stable();
267   if ((is_final() && !has_initialized_final_update()) || is_stable_field) {
268     if (is_static()) {
269       // This field just may be constant.  The only case where it will
270       // not be constant is when the field is a *special* static & final field
271       // whose value may change.  The three examples are java.lang.System.in,
272       // java.lang.System.out, and java.lang.System.err.
273       assert(vmClasses::System_klass() != NULL, "Check once per vm");
274       if (k == vmClasses::System_klass()) {
275         // Check offsets for case 2: System.in, System.out, or System.err
276         if (_offset == java_lang_System::in_offset()  ||
277             _offset == java_lang_System::out_offset() ||
278             _offset == java_lang_System::err_offset()) {
279           _is_constant = false;
280           return;
281         }
282       }

355       // Currently there is no 'shared' query for array types.
356       type_is_also_shared = !ciObjectFactory::is_initialized();
357     }
358     if (!type_is_also_shared)
359       return type;              // Bummer.
360   }
361   _type = type;
362   return type;
363 }
364 
365 
366 // ------------------------------------------------------------------
367 // ciField::will_link
368 //
369 // Can a specific access to this field be made without causing
370 // link errors?
371 bool ciField::will_link(ciMethod* accessing_method,
372                         Bytecodes::Code bc) {
373   VM_ENTRY_MARK;
374   assert(bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic ||
375          bc == Bytecodes::_getfield  || bc == Bytecodes::_putfield,
376          "unexpected bytecode");
377 
378   if (_offset == -1) {
379     // at creation we couldn't link to our holder so we need to
380     // maintain that stance, otherwise there's no safe way to use this
381     // ciField.
382     return false;
383   }
384 
385   // Check for static/nonstatic mismatch
386   bool is_static = (bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic);
387   if (is_static != this->is_static()) {
388     return false;
389   }
390 
391   // Get and put can have different accessibility rules
392   bool is_put    = (bc == Bytecodes::_putfield  || bc == Bytecodes::_putstatic);
393   if (is_put) {
394     if (_known_to_link_with_put == accessing_method) {
395       return true;
396     }

439 // ------------------------------------------------------------------
440 // ciField::print
441 void ciField::print() {
442   tty->print("<ciField name=");
443   _holder->print_name();
444   tty->print(".");
445   _name->print_symbol();
446   tty->print(" signature=");
447   _signature->print_symbol();
448   tty->print(" offset=%d type=", _offset);
449   if (_type != NULL)
450     _type->print_name();
451   else
452     tty->print("(reference)");
453   tty->print(" flags=%04x", flags().as_int());
454   tty->print(" is_constant=%s", bool_to_str(_is_constant));
455   if (_is_constant && is_static()) {
456     tty->print(" constant_value=");
457     _constant_value.print();
458   }


459   tty->print(">");
460 }
461 
462 // ------------------------------------------------------------------
463 // ciField::print_name_on
464 //
465 // Print the name of this field
466 void ciField::print_name_on(outputStream* st) {
467   name()->print_symbol_on(st);
468 }

 54 // This allows non-static field lists to be cached on shared types.
 55 // Because the _type field is lazily initialized, however, there is a
 56 // special restriction that a shared field cannot cache an unshared type.
 57 // This puts a small performance penalty on shared fields with unshared
 58 // types, such as StackTraceElement[] Throwable.stackTrace.
 59 // (Throwable is shared because ClassCastException is shared, but
 60 // StackTraceElement is not presently shared.)
 61 
 62 // It is not a vicious circularity for a ciField to recursively create
 63 // the ciSymbols necessary to represent its name and signature.
 64 // Therefore, these items are created eagerly, and the name and signature
 65 // of a shared field are themselves shared symbols.  This somewhat
 66 // pollutes the set of shared CI objects:  It grows from 50 to 93 items,
 67 // with all of the additional 43 being uninteresting shared ciSymbols.
 68 // This adds at most one step to the binary search, an amount which
 69 // decreases for complex compilation tasks.
 70 
 71 // ------------------------------------------------------------------
 72 // ciField::ciField
 73 ciField::ciField(ciInstanceKlass* klass, int index) :
 74   _is_flattened(false), _known_to_link_with_put(NULL), _known_to_link_with_get(NULL) {
 75   ASSERT_IN_VM;
 76   CompilerThread *THREAD = CompilerThread::current();
 77 
 78   assert(ciObjectFactory::is_initialized(), "not a shared field");
 79 
 80   assert(klass->get_instanceKlass()->is_linked(), "must be linked before using its constant-pool");
 81 
 82   constantPoolHandle cpool(THREAD, klass->get_instanceKlass()->constants());
 83 
 84   // Get the field's name, signature, and type.
 85   Symbol* name  = cpool->name_ref_at(index);
 86   _name = ciEnv::current(THREAD)->get_symbol(name);
 87 
 88   int nt_index = cpool->name_and_type_ref_index_at(index);
 89   int sig_index = cpool->signature_ref_index_at(nt_index);
 90   Symbol* signature = cpool->symbol_at(sig_index);
 91   _signature = ciEnv::current(THREAD)->get_symbol(signature);
 92 
 93   BasicType field_type = Signature::basic_type(signature);
 94 
 95   // If the field is a pointer type, get the klass of the
 96   // field.
 97   if (is_reference_type(field_type)) {
 98     bool ignore;
 99     // This is not really a class reference; the index always refers to the
100     // field's type signature, as a symbol.  Linkage checks do not apply.
101     _type = ciEnv::current(THREAD)->get_klass_by_index(cpool, sig_index, ignore, klass);
102   } else {
103     _type = ciType::make(field_type);
104   }
105 
106   _name = (ciSymbol*)ciEnv::current(THREAD)->get_symbol(name);
107 
108   // this is needed if the field class is not yet loaded.
109   _is_null_free = _signature->is_Q_signature();
110 
111   // Get the field's declared holder.
112   //
113   // Note: we actually create a ciInstanceKlass for this klass,
114   // even though we may not need to.
115   int holder_index = cpool->klass_ref_index_at(index);
116   bool holder_is_accessible;
117 
118   ciKlass* generic_declared_holder = ciEnv::current(THREAD)->get_klass_by_index(cpool, holder_index,
119                                                                                 holder_is_accessible,
120                                                                                 klass);
121 
122   if (generic_declared_holder->is_array_klass()) {
123     // If the declared holder of the field is an array class, assume that
124     // the canonical holder of that field is java.lang.Object. Arrays
125     // do not have fields; java.lang.Object is the only supertype of an
126     // array type that can declare fields and is therefore the canonical
127     // holder of the array type.
128     //
129     // Furthermore, the compilers assume that java.lang.Object does not
130     // have any fields. Therefore, the field is not looked up. Instead,

202   _name = env->get_symbol(fd->name());
203   _signature = env->get_symbol(fd->signature());
204 
205   BasicType field_type = fd->field_type();
206 
207   // If the field is a pointer type, get the klass of the
208   // field.
209   if (is_reference_type(field_type)) {
210     _type = NULL;  // must call compute_type on first access
211   } else {
212     _type = ciType::make(field_type);
213   }
214 
215   initialize_from(fd);
216 
217   // Either (a) it is marked shared, or else (b) we are done bootstrapping.
218   assert(is_shared() || ciObjectFactory::is_initialized(),
219          "bootstrap classes must not create & cache unshared fields");
220 }
221 
222 // Special copy constructor used to flatten inline type fields by
223 // copying the fields of the inline type to a new holder klass.
224 ciField::ciField(ciField* field, ciInstanceKlass* holder, int offset, bool is_final) {
225   assert(field->holder()->is_inlinetype(), "should only be used for inline type field flattening");
226   // Set the is_final flag
227   jint final = is_final ? JVM_ACC_FINAL : ~JVM_ACC_FINAL;
228   AccessFlags flags(field->flags().as_int() & final);
229   _flags = ciFlags(flags);
230   _holder = holder;
231   _offset = offset;
232   // Copy remaining fields
233   _name = field->_name;
234   _signature = field->_signature;
235   _type = field->_type;
236   // Trust final flattened fields
237   _is_constant = is_final;
238   _known_to_link_with_put = field->_known_to_link_with_put;
239   _known_to_link_with_get = field->_known_to_link_with_get;
240   _constant_value = field->_constant_value;
241   assert(!field->is_flattened(), "field must not be flattened");
242   _is_flattened = false;
243   _is_null_free = field->is_null_free();
244 }
245 
246 static bool trust_final_non_static_fields(ciInstanceKlass* holder) {
247   if (holder == NULL)
248     return false;
249   if (holder->name() == ciSymbols::java_lang_System())
250     // Never trust strangely unstable finals:  System.out, etc.
251     return false;
252   // Even if general trusting is disabled, trust system-built closures in these packages.
253   if (holder->is_in_package("java/lang/invoke") || holder->is_in_package("sun/invoke") ||
254       holder->is_in_package("java/lang/reflect") || holder->is_in_package("jdk/internal/reflect") ||
255       holder->is_in_package("jdk/internal/foreign") || holder->is_in_package("jdk/incubator/foreign") ||
256       holder->is_in_package("jdk/internal/vm/vector") || holder->is_in_package("jdk/incubator/vector") ||
257       holder->is_in_package("java/lang"))
258     return true;
259   // Trust hidden classes. They are created via Lookup.defineHiddenClass and
260   // can't be serialized, so there is no hacking of finals going on with them.
261   if (holder->is_hidden())
262     return true;
263   // Trust final fields in inline type buffers
264   if (holder->is_inlinetype())
265     return true;
266   // Trust final fields in all boxed classes
267   if (holder->is_box_klass())
268     return true;
269   // Trust final fields in records
270   if (holder->is_record())
271     return true;
272   // Trust final fields in String
273   if (holder->name() == ciSymbols::java_lang_String())
274     return true;
275   // Trust Atomic*FieldUpdaters: they are very important for performance, and make up one
276   // more reason not to use Unsafe, if their final fields are trusted. See more in JDK-8140483.
277   if (holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicIntegerFieldUpdater_Impl() ||
278       holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicLongFieldUpdater_CASUpdater() ||
279       holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicLongFieldUpdater_LockedUpdater() ||
280       holder->name() == ciSymbols::java_util_concurrent_atomic_AtomicReferenceFieldUpdater_Impl()) {
281     return true;
282   }
283   return TrustFinalNonStaticFields;
284 }
285 
286 void ciField::initialize_from(fieldDescriptor* fd) {
287   // Get the flags, offset, and canonical holder of the field.
288   _flags = ciFlags(fd->access_flags());
289   _offset = fd->offset();
290   Klass* field_holder = fd->field_holder();
291   assert(field_holder != NULL, "null field_holder");
292   _holder = CURRENT_ENV->get_instance_klass(field_holder);
293   _is_flattened = fd->is_inlined();
294   _is_null_free = fd->signature()->is_Q_signature();
295 
296   // Check to see if the field is constant.
297   Klass* k = _holder->get_Klass();
298   bool is_stable_field = FoldStableValues && is_stable();
299   if ((is_final() && !has_initialized_final_update()) || is_stable_field) {
300     if (is_static()) {
301       // This field just may be constant.  The only case where it will
302       // not be constant is when the field is a *special* static & final field
303       // whose value may change.  The three examples are java.lang.System.in,
304       // java.lang.System.out, and java.lang.System.err.
305       assert(vmClasses::System_klass() != NULL, "Check once per vm");
306       if (k == vmClasses::System_klass()) {
307         // Check offsets for case 2: System.in, System.out, or System.err
308         if (_offset == java_lang_System::in_offset()  ||
309             _offset == java_lang_System::out_offset() ||
310             _offset == java_lang_System::err_offset()) {
311           _is_constant = false;
312           return;
313         }
314       }

387       // Currently there is no 'shared' query for array types.
388       type_is_also_shared = !ciObjectFactory::is_initialized();
389     }
390     if (!type_is_also_shared)
391       return type;              // Bummer.
392   }
393   _type = type;
394   return type;
395 }
396 
397 
398 // ------------------------------------------------------------------
399 // ciField::will_link
400 //
401 // Can a specific access to this field be made without causing
402 // link errors?
403 bool ciField::will_link(ciMethod* accessing_method,
404                         Bytecodes::Code bc) {
405   VM_ENTRY_MARK;
406   assert(bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic ||
407          bc == Bytecodes::_getfield  || bc == Bytecodes::_putfield  ||
408          bc == Bytecodes::_withfield, "unexpected bytecode");
409 
410   if (_offset == -1) {
411     // at creation we couldn't link to our holder so we need to
412     // maintain that stance, otherwise there's no safe way to use this
413     // ciField.
414     return false;
415   }
416 
417   // Check for static/nonstatic mismatch
418   bool is_static = (bc == Bytecodes::_getstatic || bc == Bytecodes::_putstatic);
419   if (is_static != this->is_static()) {
420     return false;
421   }
422 
423   // Get and put can have different accessibility rules
424   bool is_put    = (bc == Bytecodes::_putfield  || bc == Bytecodes::_putstatic);
425   if (is_put) {
426     if (_known_to_link_with_put == accessing_method) {
427       return true;
428     }

471 // ------------------------------------------------------------------
472 // ciField::print
473 void ciField::print() {
474   tty->print("<ciField name=");
475   _holder->print_name();
476   tty->print(".");
477   _name->print_symbol();
478   tty->print(" signature=");
479   _signature->print_symbol();
480   tty->print(" offset=%d type=", _offset);
481   if (_type != NULL)
482     _type->print_name();
483   else
484     tty->print("(reference)");
485   tty->print(" flags=%04x", flags().as_int());
486   tty->print(" is_constant=%s", bool_to_str(_is_constant));
487   if (_is_constant && is_static()) {
488     tty->print(" constant_value=");
489     _constant_value.print();
490   }
491   tty->print(" is_flattened=%s", bool_to_str(_is_flattened));
492   tty->print(" is_null_free=%s", bool_to_str(_is_null_free));
493   tty->print(">");
494 }
495 
496 // ------------------------------------------------------------------
497 // ciField::print_name_on
498 //
499 // Print the name of this field
500 void ciField::print_name_on(outputStream* st) {
501   name()->print_symbol_on(st);
502 }
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