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src/hotspot/share/code/vtableStubs.hpp

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 71 // VtableStubs creates the code stubs for compiled calls through vtables.
 72 // There is one stub per (vtable index, args_size) pair, and the stubs are
 73 // never deallocated. They don't need to be GCed because they contain no oops.
 74 class VtableStub;
 75 
 76 class VtableStubs : AllStatic {
 77  public:                                         // N must be public (some compilers need this for _table)
 78   enum {
 79     N    = 256,                                  // size of stub table; must be power of two
 80     mask = N - 1
 81   };
 82 
 83   static_assert(is_power_of_2((int)N), "N must be a power of 2");
 84 
 85  private:
 86   friend class VtableStub;
 87   static VtableStub* volatile _table[N];                  // table of existing stubs
 88   static int         _vtab_stub_size;            // current size estimate for vtable stub (quasi-constant)
 89   static int         _itab_stub_size;            // current size estimate for itable stub (quasi-constant)
 90 
 91   static VtableStub* create_vtable_stub(int vtable_index);
 92   static VtableStub* create_itable_stub(int vtable_index);
 93   static VtableStub* lookup            (bool is_vtable_stub, int vtable_index);
 94   static void        enter             (bool is_vtable_stub, int vtable_index, VtableStub* s);
 95   static inline uint hash              (bool is_vtable_stub, int vtable_index);
 96   static address     find_stub         (bool is_vtable_stub, int vtable_index);
 97   static void        bookkeeping(MacroAssembler* masm, outputStream* out, VtableStub* s,
 98                                  address npe_addr, address ame_addr,   bool is_vtable_stub,
 99                                  int     index,    int     slop_bytes, int  index_dependent_slop);
100   static int         code_size_limit(bool is_vtable_stub);
101   static void        check_and_set_size_limit(bool is_vtable_stub,
102                                               int   code_size,
103                                               int   padding);
104 
105  public:
106   static address     find_vtable_stub(int vtable_index) { return find_stub(true,  vtable_index); }
107   static address     find_itable_stub(int itable_index) { return find_stub(false, itable_index); }
108 
109   static VtableStub* entry_point(address pc);                        // vtable stub entry point for a pc
110   static bool        is_icholder_entry(address pc);                  // is the blob containing pc (which must be a vtable blob) an icholder?
111   static bool        contains(address pc);                           // is pc within any stub?
112   static VtableStub* stub_containing(address pc);                    // stub containing pc or nullptr
113   static void        initialize();
114   static void        vtable_stub_do(void f(VtableStub*));            // iterates over all vtable stubs
115 };
116 
117 
118 class VtableStub {
119  private:
120   friend class VtableStubs;
121 
122   static address _chunk;             // For allocation
123   static address _chunk_end;         // For allocation
124   static VMReg   _receiver_location; // Where to find receiver
125 
126   VtableStub*    _next;              // Pointer to next entry in hash table
127   const short    _index;             // vtable index
128   short          _ame_offset;        // Where an AbstractMethodError might occur
129   short          _npe_offset;        // Where a NullPointerException might occur
130   bool           _is_vtable_stub;    // True if vtable stub, false, is itable stub


131   /* code follows here */            // The vtableStub code
132 
133   void* operator new(size_t size, int code_size) throw();
134 
135   VtableStub(bool is_vtable_stub, short index)
136         : _next(nullptr), _index(index), _ame_offset(-1), _npe_offset(-1),
137           _is_vtable_stub(is_vtable_stub) {}
138   VtableStub* next() const                       { return _next; }
139   int index() const                              { return _index; }
140   static VMReg receiver_location()               { return _receiver_location; }
141   void set_next(VtableStub* n)                   { _next = n; }
142 
143  public:
144   address code_begin() const                     { return (address)(this + 1); }
145   address code_end() const                       { return code_begin() + VtableStubs::code_size_limit(_is_vtable_stub); }
146   address entry_point() const                    { return code_begin(); }
147   static int entry_offset()                      { return sizeof(class VtableStub); }
148 
149   bool matches(bool is_vtable_stub, int index) const {
150     return _index == index && _is_vtable_stub == is_vtable_stub;
151   }
152   bool contains(address pc) const                { return code_begin() <= pc && pc < code_end(); }
153 
154  private:
155   void set_exception_points(address npe_addr, address ame_addr) {
156     _npe_offset = checked_cast<short>(npe_addr - code_begin());
157     _ame_offset = checked_cast<short>(ame_addr - code_begin());
158     assert(is_abstract_method_error(ame_addr),   "offset must be correct");
159     assert(is_null_pointer_exception(npe_addr),  "offset must be correct");
160     assert(!is_abstract_method_error(npe_addr),  "offset must be correct");
161     assert(!is_null_pointer_exception(ame_addr), "offset must be correct");
162   }
163 
164   // platform-dependent routines
165   static int  pd_code_alignment();
166   // CNC: Removed because vtable stubs are now made with an ideal graph
167   // static bool pd_disregard_arg_size();
168 
169   static void align_chunk() {
170     uintptr_t off = (uintptr_t)( _chunk + sizeof(VtableStub) ) % pd_code_alignment();
171     if (off != 0)  _chunk += pd_code_alignment() - off;
172   }
173 
174  public:
175   // Query
176   bool is_itable_stub()                          { return !_is_vtable_stub; }
177   bool is_vtable_stub()                          { return  _is_vtable_stub; }

178   bool is_abstract_method_error(address epc)     { return epc == code_begin()+_ame_offset; }
179   bool is_null_pointer_exception(address epc)    { return epc == code_begin()+_npe_offset; }
180 
181   void print_on(outputStream* st) const;
182   void print() const;
183 
184 };
185 
186 #endif // SHARE_CODE_VTABLESTUBS_HPP

 71 // VtableStubs creates the code stubs for compiled calls through vtables.
 72 // There is one stub per (vtable index, args_size) pair, and the stubs are
 73 // never deallocated. They don't need to be GCed because they contain no oops.
 74 class VtableStub;
 75 
 76 class VtableStubs : AllStatic {
 77  public:                                         // N must be public (some compilers need this for _table)
 78   enum {
 79     N    = 256,                                  // size of stub table; must be power of two
 80     mask = N - 1
 81   };
 82 
 83   static_assert(is_power_of_2((int)N), "N must be a power of 2");
 84 
 85  private:
 86   friend class VtableStub;
 87   static VtableStub* volatile _table[N];                  // table of existing stubs
 88   static int         _vtab_stub_size;            // current size estimate for vtable stub (quasi-constant)
 89   static int         _itab_stub_size;            // current size estimate for itable stub (quasi-constant)
 90 
 91   static VtableStub* create_vtable_stub(int vtable_index, bool caller_is_c1);
 92   static VtableStub* create_itable_stub(int vtable_index, bool caller_is_c1);
 93   static VtableStub* lookup            (bool is_vtable_stub, int vtable_index, bool caller_is_c1);
 94   static void        enter             (bool is_vtable_stub, int vtable_index, bool caller_is_c1, VtableStub* s);
 95   static inline uint hash              (bool is_vtable_stub, int vtable_index, bool caller_is_c1);
 96   static address     find_stub         (bool is_vtable_stub, int vtable_index, bool caller_is_c1);
 97   static void        bookkeeping(MacroAssembler* masm, outputStream* out, VtableStub* s,
 98                                  address npe_addr, address ame_addr,   bool is_vtable_stub,
 99                                  int     index,    int     slop_bytes, int  index_dependent_slop);
100   static int         code_size_limit(bool is_vtable_stub);
101   static void        check_and_set_size_limit(bool is_vtable_stub,
102                                               int   code_size,
103                                               int   padding);
104 
105  public:
106   static address     find_vtable_stub(int vtable_index, bool caller_is_c1) { return find_stub(true,  vtable_index, caller_is_c1); }
107   static address     find_itable_stub(int itable_index, bool caller_is_c1) { return find_stub(false, itable_index, caller_is_c1); }
108 
109   static VtableStub* entry_point(address pc);                        // vtable stub entry point for a pc
110   static bool        is_icholder_entry(address pc);                  // is the blob containing pc (which must be a vtable blob) an icholder?
111   static bool        contains(address pc);                           // is pc within any stub?
112   static VtableStub* stub_containing(address pc);                    // stub containing pc or nullptr
113   static void        initialize();
114   static void        vtable_stub_do(void f(VtableStub*));            // iterates over all vtable stubs
115 };
116 
117 
118 class VtableStub {
119  private:
120   friend class VtableStubs;
121 
122   static address _chunk;             // For allocation
123   static address _chunk_end;         // For allocation
124   static VMReg   _receiver_location; // Where to find receiver
125 
126   VtableStub*    _next;              // Pointer to next entry in hash table
127   const short    _index;             // vtable index
128   short          _ame_offset;        // Where an AbstractMethodError might occur
129   short          _npe_offset;        // Where a NullPointerException might occur
130   bool           _is_vtable_stub;    // True if vtable stub, false, is itable stub
131   bool           _caller_is_c1;      // True if this is for a caller compiled by C1,
132                                      // which doesn't scalarize parameters.
133   /* code follows here */            // The vtableStub code
134 
135   void* operator new(size_t size, int code_size) throw();
136 
137   VtableStub(bool is_vtable_stub, short index, bool caller_is_c1)
138         : _next(nullptr), _index(index), _ame_offset(-1), _npe_offset(-1),
139           _is_vtable_stub(is_vtable_stub), _caller_is_c1(caller_is_c1) {}
140   VtableStub* next() const                       { return _next; }
141   int index() const                              { return _index; }
142   static VMReg receiver_location()               { return _receiver_location; }
143   void set_next(VtableStub* n)                   { _next = n; }
144 
145  public:
146   address code_begin() const                     { return (address)(this + 1); }
147   address code_end() const                       { return code_begin() + VtableStubs::code_size_limit(_is_vtable_stub); }
148   address entry_point() const                    { return code_begin(); }
149   static int entry_offset()                      { return sizeof(class VtableStub); }
150 
151   bool matches(bool is_vtable_stub, int index, bool caller_is_c1) const {
152     return _index == index && _is_vtable_stub == is_vtable_stub && _caller_is_c1 == caller_is_c1;
153   }
154   bool contains(address pc) const                { return code_begin() <= pc && pc < code_end(); }
155 
156  private:
157   void set_exception_points(address npe_addr, address ame_addr) {
158     _npe_offset = checked_cast<short>(npe_addr - code_begin());
159     _ame_offset = checked_cast<short>(ame_addr - code_begin());
160     assert(is_abstract_method_error(ame_addr),   "offset must be correct");
161     assert(is_null_pointer_exception(npe_addr),  "offset must be correct");
162     assert(!is_abstract_method_error(npe_addr),  "offset must be correct");
163     assert(!is_null_pointer_exception(ame_addr), "offset must be correct");
164   }
165 
166   // platform-dependent routines
167   static int  pd_code_alignment();
168   // CNC: Removed because vtable stubs are now made with an ideal graph
169   // static bool pd_disregard_arg_size();
170 
171   static void align_chunk() {
172     uintptr_t off = (uintptr_t)( _chunk + sizeof(VtableStub) ) % pd_code_alignment();
173     if (off != 0)  _chunk += pd_code_alignment() - off;
174   }
175 
176  public:
177   // Query
178   bool is_itable_stub()                          { return !_is_vtable_stub; }
179   bool is_vtable_stub()                          { return  _is_vtable_stub; }
180   bool caller_is_c1()                            { return  _caller_is_c1;   }
181   bool is_abstract_method_error(address epc)     { return epc == code_begin()+_ame_offset; }
182   bool is_null_pointer_exception(address epc)    { return epc == code_begin()+_npe_offset; }
183 
184   void print_on(outputStream* st) const;
185   void print() const;
186 
187 };
188 
189 #endif // SHARE_CODE_VTABLESTUBS_HPP
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