1 /*
   2  * Copyright (c) 1997, 2019, 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_RUNTIME_FIELDTYPE_HPP
  26 #define SHARE_RUNTIME_FIELDTYPE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "oops/arrayStorageProperties.hpp"
  30 #include "oops/symbol.hpp"
  31 
  32 // Note: FieldType should be based on the SignatureIterator (or vice versa).
  33 //       In any case, this structure should be re-thought at some point.
  34 
  35 // A FieldType is used to determine the type of a field from a signature string.
  36 
  37 // Information returned by get_array_info, which is scoped to decrement
  38 // reference count if a Symbol is created in the case of T_OBJECT
  39 class FieldArrayInfo : public StackObj {
  40   friend class FieldType;  // field type can set these fields.
  41   int       _dimension;
  42   Symbol*   _object_key;
  43   ArrayStorageProperties _storage_props;
  44  public:
  45   int       dimension()    { return _dimension; }
  46   Symbol*   object_key()   { return _object_key; }
  47   ArrayStorageProperties storage_props() { return _storage_props; }
  48   // basic constructor
  49   FieldArrayInfo() : _dimension(0), _object_key(NULL), _storage_props(ArrayStorageProperties::empty) {}
  50   // destructor decrements object key's refcount if created
  51   ~FieldArrayInfo() { if (_object_key != NULL) _object_key->decrement_refcount(); }
  52 };
  53 
  54 
  55 class FieldType: public AllStatic {
  56  private:
  57   static bool is_valid_array_signature(Symbol* signature);
  58  public:
  59 
  60   // Return basic type
  61   static BasicType basic_type(Symbol* signature);
  62 
  63   // Testing
  64   static bool is_array(Symbol* signature) { return signature->utf8_length() > 1 && signature->char_at(0) == '[' && is_valid_array_signature(signature); }
  65 
  66   static bool is_obj(Symbol* signature) {
  67      int sig_length = signature->utf8_length();
  68      // Must start with 'L' and end with ';'
  69      return (sig_length >= 2 &&
  70              (signature->char_at(0) == 'L') &&
  71              (signature->char_at(sig_length - 1) == ';'));
  72   }
  73 
  74   static bool is_valuetype(Symbol* signature) {
  75     return signature->is_Q_signature();
  76   }
  77 
  78   // Parse field and extract array information. Works for T_ARRAY only.
  79   static BasicType get_array_info(Symbol* signature, FieldArrayInfo& ai, TRAPS);
  80 
  81   // LWorld (LW2) Q-type array descriptors require null-free, and preferably flat if possible
  82   static ArrayStorageProperties get_array_storage_properties(Symbol* signature);
  83 };
  84 
  85 #endif // SHARE_RUNTIME_FIELDTYPE_HPP
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