1 /*
   2  * Copyright (c) 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_VALUEKLASS_HPP
  26 #define SHARE_VM_OOPS_VALUEKLASS_HPP
  27 
  28 #include "oops/instanceKlass.hpp"
  29 #include "oops/method.hpp"
  30 #include "oops/oop.inline.hpp"
  31 
  32 // A ValueKlass is a specialized InstanceKlass for value types.
  33 
  34 
  35 class ValueKlass: public InstanceKlass {
  36   friend class VMStructs;
  37   friend class InstanceKlass;
  38 
  39 private:
  40 
  41   // Constructor
  42   ValueKlass(const ClassFileParser& parser)
  43     : InstanceKlass(parser, InstanceKlass::_misc_kind_value_type) {
  44     set_has_vcc_klass();
  45   }
  46 
  47   // static Klass* array_klass_impl(InstanceKlass* this_k, bool or_null, int n, TRAPS);
  48  protected:
  49   // Returns the array class for the n'th dimension
  50   Klass* array_klass_impl(bool or_null, int n, TRAPS);
  51 
  52   // Returns the array class with this class as element type
  53   Klass* array_klass_impl(bool or_null, TRAPS);
  54 
  55  public:
  56   // Type testing
  57   bool is_value_slow() const        { return true; }
  58 
  59   // Casting from Klass*
  60   static ValueKlass* cast(Klass* k) {
  61     assert(k->is_value(), "cast to ValueKlass");
  62     return (ValueKlass*) k;
  63   }
  64 
  65   // Use this to return the size of an instance in heap words
  66   // Implementation is currently simple because all value types are allocated
  67   // in Java heap like Java objects.
  68   virtual int size_helper() const {
  69     return layout_helper_to_size_helper(layout_helper());
  70   }
  71 
  72   // allocate_instance() allocates a stand alone value in the Java heap
  73   instanceOop allocate_instance(TRAPS);
  74   // allocate_buffered_or_heap_instance() tries to allocate a value in the
  75   // thread local value buffer, if allocation fails, it allocates it in the
  76   // Java heap
  77   instanceOop allocate_buffered_or_heap_instance(bool* in_heap, TRAPS);
  78 
  79   // minimum number of bytes occupied by nonstatic fields, HeapWord aligned or pow2
  80   int raw_value_byte_size() const;
  81 
  82   int first_field_offset() const;
  83 
  84   address data_for_oop(oop o) const {
  85     return ((address) (void*) o) + first_field_offset();
  86   }
  87 
  88    oop oop_for_data(address data) const {
  89     oop o = (oop) (data - first_field_offset());
  90     assert(o->is_oop(false), "Not an oop");
  91     return o;
  92   }
  93 
  94    void set_if_bufferable() {
  95      bool bufferable;
  96      if (contains_oops()) {
  97        bufferable = false;
  98      } else {
  99        int size_in_heap_words = size_helper();
 100        int base_offset = instanceOopDesc::base_offset_in_bytes();
 101        size_t size_in_bytes = size_in_heap_words * HeapWordSize - base_offset;
 102        bufferable = size_in_bytes <= BigValueTypeThreshold;
 103      }
 104      if (bufferable) {
 105        _extra_flags |= _extra_is_bufferable;
 106      } else {
 107        _extra_flags &= ~_extra_is_bufferable;
 108      }
 109    }
 110 
 111   bool is_bufferable() const          {
 112     return (_extra_flags & _extra_is_bufferable) != 0;
 113   }
 114 
 115   // Query if h/w provides atomic load/store
 116   bool is_atomic();
 117 
 118   bool flatten_array();
 119 
 120   bool contains_oops() const { return nonstatic_oop_map_count() > 0; }
 121   int nonstatic_oop_count();
 122 
 123   // Prototype general store methods...
 124 
 125   // copy the fields, with no concern for GC barriers
 126   void raw_field_copy(void* src, void* dst, size_t raw_byte_size);
 127 
 128   void value_store(void* src, void* dst, bool dst_is_heap, bool dst_uninitialized) {
 129     value_store(src, dst, nonstatic_field_size() << LogBytesPerHeapOop, dst_is_heap, dst_uninitialized);
 130   }
 131 
 132   // store the value of this klass contained with src into dst, raw data ptr
 133   void value_store(void* src, void* dst, size_t raw_byte_size, bool dst_is_heap, bool dst_uninitialized);
 134 
 135   oop unbox(Handle src, InstanceKlass* target_klass, TRAPS);
 136   oop box(Handle src, InstanceKlass* target_klass, TRAPS);
 137 
 138   // GC support...
 139 
 140   // oop iterate raw value type data pointer (where oop_addr may not be an oop, but backing/array-element)
 141   template <bool nv, typename T, class OopClosureType>
 142   inline void oop_iterate_specialized(const address oop_addr, OopClosureType* closure);
 143 
 144   template <bool nv, typename T, class OopClosureType>
 145   inline void oop_iterate_specialized_bounded(const address oop_addr, OopClosureType* closure, void* lo, void* hi);
 146 
 147   // calling convention support
 148   GrowableArray<SigEntry> collect_fields(int base_off = 0) const;
 149   GrowableArray<SigEntry> return_convention(VMRegPair*& regs, int& nb_fields) const;
 150   void save_oop_fields(const GrowableArray<SigEntry>& sig_vk, RegisterMap& map, const VMRegPair* regs, GrowableArray<Handle>& handles, int nb_fields) const;
 151   bool save_oop_results(RegisterMap& map, GrowableArray<Handle>& handles) const;
 152   void restore_oop_results(RegisterMap& map, GrowableArray<Handle>& handles) const;
 153   oop realloc_result(const GrowableArray<SigEntry>& sig_vk, const RegisterMap& reg_map, const VMRegPair* regs, const GrowableArray<Handle>& handles, int nb_fields, TRAPS);
 154   static ValueKlass* returned_value_type(const RegisterMap& reg_map);
 155 };
 156 
 157 #endif /* SHARE_VM_OOPS_VALUEKLASS_HPP */