1 /*

     2  * Copyright (c) 2011, 2017, 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 #ifndef SHARE_VM_OOPS_FIELDSTREAMS_HPP

    26 #define SHARE_VM_OOPS_FIELDSTREAMS_HPP

    27 

    28 #include "oops/instanceKlass.hpp"

    29 #include "oops/fieldInfo.hpp"

    30 #include "runtime/fieldDescriptor.hpp"

    31 

    32 // The is the base class for iteration over the fields array

    33 // describing the declared fields in the class.  Several subclasses

    34 // are provided depending on the kind of iteration required.  The

    35 // JavaFieldStream is for iterating over regular Java fields and it

    36 // generally the preferred iterator.  InternalFieldStream only

    37 // iterates over fields that have been injected by the JVM.

    38 // AllFieldStream exposes all fields and should only be used in rare

    39 // cases.

    40 class FieldStreamBase : public StackObj {

    41  protected:

    42   Array<u2>*          _fields;

    43   constantPoolHandle  _constants;

    44   int                 _index;

    45   int                 _limit;

    46   int                 _generic_signature_slot;

    47   fieldDescriptor     _fd_buf;

    48 

    49   FieldInfo* field() const { return FieldInfo::from_field_array(_fields, _index); }

    50   InstanceKlass* field_holder() const { return _constants->pool_holder(); }

    51 

    52   int init_generic_signature_start_slot() {

    53     int length = _fields->length();

    54     int num_fields = _index;

    55     int skipped_generic_signature_slots = 0;

    56     FieldInfo* fi;

    57     AccessFlags flags;

    58     /* Scan from 0 to the current _index. Count the number of generic

    59        signature slots for field[0] to field[_index - 1]. */

    60     for (int i = 0; i < _index; i++) {

    61       fi = FieldInfo::from_field_array(_fields, i);

    62       flags.set_flags(fi->access_flags());

    63       if (flags.field_has_generic_signature()) {

    64         length --;

    65         skipped_generic_signature_slots ++;

    66       }

    67     }

    68     /* Scan from the current _index. */

    69     for (int i = _index; i*FieldInfo::field_slots < length; i++) {

    70       fi = FieldInfo::from_field_array(_fields, i);

    71       flags.set_flags(fi->access_flags());

    72       if (flags.field_has_generic_signature()) {

    73         length --;

    74       }

    75       num_fields ++;

    76     }

    77     _generic_signature_slot = length + skipped_generic_signature_slots;

    78     assert(_generic_signature_slot <= _fields->length(), "");

    79     return num_fields;

    80   }

    81 

    82   FieldStreamBase(Array<u2>* fields, const constantPoolHandle& constants, int start, int limit) {

    83     _fields = fields;

    84     _constants = constants;

    85     _index = start;

    86     int num_fields = init_generic_signature_start_slot();

    87     if (limit < start) {

    88       _limit = num_fields;

    89     } else {

    90       _limit = limit;

    91     }

    92   }

    93 

    94   FieldStreamBase(Array<u2>* fields, const constantPoolHandle& constants) {

    95     _fields = fields;

    96     _constants = constants;

    97     _index = 0;

    98     _limit = init_generic_signature_start_slot();

    99   }

   100 

   101  public:

   102   FieldStreamBase(InstanceKlass* klass) {

   103     _fields = klass->fields();

   104     _constants = klass->constants();

   105     _index = 0;

   106     _limit = klass->java_fields_count();

   107     init_generic_signature_start_slot();

   108     assert(klass == field_holder(), "");

   109   }

   110 

   111   // accessors

   112   int index() const                 { return _index; }

   113 

   114   void next() {

   115     if (access_flags().field_has_generic_signature()) {

   116       _generic_signature_slot ++;

   117       assert(_generic_signature_slot <= _fields->length(), "");

   118     }

   119     _index += 1;

   120   }

   121   bool done() const { return _index >= _limit; }

   122 

   123   // Accessors for current field

   124   AccessFlags access_flags() const {

   125     AccessFlags flags;

   126     flags.set_flags(field()->access_flags());

   127     return flags;

   128   }

   129 

   130   void set_access_flags(u2 flags) const {

   131     field()->set_access_flags(flags);

   132   }

   133 

   134   void set_access_flags(AccessFlags flags) const {

   135     set_access_flags(flags.as_short());

   136   }

   137 

   138   Symbol* name() const {

   139     return field()->name(_constants);

   140   }

   141 

   142   Symbol* signature() const {

   143     return field()->signature(_constants);

   144   }

   145 

   146   Symbol* generic_signature() const {

   147     if (access_flags().field_has_generic_signature()) {

   148       assert(_generic_signature_slot < _fields->length(), "out of bounds");

   149       int index = _fields->at(_generic_signature_slot);

   150       return _constants->symbol_at(index);

   151     } else {

   152       return NULL;

   153     }

   154   }

   155 

   156   int offset() const {

   157     return field()->offset();

   158   }

   159 

   160   int allocation_type() const {

   161     return field()->allocation_type();

   162   }

   163 

   164   void set_offset(int offset) {

   165     field()->set_offset(offset);

   166   }

   167 

   168   bool is_offset_set() const {

   169     return field()->is_offset_set();

   170   }

   171 

   172   bool is_contended() const {

   173     return field()->is_contended();

   174   }

   175 

   176   int contended_group() const {

   177     return field()->contended_group();

   178   }

   179 

   180   // bridge to a heavier API:

   181   fieldDescriptor& field_descriptor() const {

   182     fieldDescriptor& field = const_cast<fieldDescriptor&>(_fd_buf);

   183     field.reinitialize(field_holder(), _index);

   184     return field;

   185   }

   186 };

   187 

   188 // Iterate over only the internal fields

   189 class JavaFieldStream : public FieldStreamBase {

   190  public:

   191   JavaFieldStream(const InstanceKlass* k): FieldStreamBase(k->fields(), k->constants(), 0, k->java_fields_count()) {}

   192 

   193   int name_index() const {

   194     assert(!field()->is_internal(), "regular only");

   195     return field()->name_index();

   196   }

   197   void set_name_index(int index) {

   198     assert(!field()->is_internal(), "regular only");

   199     field()->set_name_index(index);

   200   }

   201   int signature_index() const {

   202     assert(!field()->is_internal(), "regular only");

   203     return field()->signature_index();

   204   }

   205   void set_signature_index(int index) {

   206     assert(!field()->is_internal(), "regular only");

   207     field()->set_signature_index(index);

   208   }

   209   int generic_signature_index() const {

   210     assert(!field()->is_internal(), "regular only");

   211     if (access_flags().field_has_generic_signature()) {

   212       assert(_generic_signature_slot < _fields->length(), "out of bounds");

   213       return _fields->at(_generic_signature_slot);

   214     } else {

   215       return 0;

   216     }

   217   }

   218   void set_generic_signature_index(int index) {

   219     assert(!field()->is_internal(), "regular only");

   220     if (access_flags().field_has_generic_signature()) {

   221       assert(_generic_signature_slot < _fields->length(), "out of bounds");

   222       _fields->at_put(_generic_signature_slot, index);

   223     }

   224   }

   225   int initval_index() const {

   226     assert(!field()->is_internal(), "regular only");

   227     return field()->initval_index();

   228   }

   229   void set_initval_index(int index) {

   230     assert(!field()->is_internal(), "regular only");

   231     return field()->set_initval_index(index);

   232   }

   233 };

   234 

   235 

   236 // Iterate over only the internal fields

   237 class InternalFieldStream : public FieldStreamBase {

   238  public:

   239   InternalFieldStream(InstanceKlass* k):      FieldStreamBase(k->fields(), k->constants(), k->java_fields_count(), 0) {}

   240 };

   241 

   242 

   243 class AllFieldStream : public FieldStreamBase {

   244  public:

   245   AllFieldStream(Array<u2>* fields, const constantPoolHandle& constants): FieldStreamBase(fields, constants) {}

   246   AllFieldStream(InstanceKlass* k):      FieldStreamBase(k->fields(), k->constants()) {}

   247 };

   248 

   249 #endif // SHARE_VM_OOPS_FIELDSTREAMS_HPP