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 /*

  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

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  */

 #ifndef SHARE_VM_CODE_VTABLESTUBS_HPP

 #define SHARE_VM_CODE_VTABLESTUBS_HPP

 #include "code/vmreg.hpp"

 #include "memory/allocation.hpp"

 // A VtableStub holds an individual code stub for a pair (vtable index, #args) for either itables or vtables

 // There's a one-to-one relationship between a VtableStub and such a pair.

 class VtableStub {

  private:

   friend class VtableStubs;

   static address _chunk;             // For allocation

   static address _chunk_end;         // For allocation

   static VMReg   _receiver_location; // Where to find receiver

   VtableStub*    _next;              // Pointer to next entry in hash table

   const short    _index;             // vtable index

   short          _ame_offset;        // Where an AbstractMethodError might occur

   short          _npe_offset;        // Where a NullPointerException might occur

   bool           _is_vtable_stub;    // True if vtable stub, false, is itable stub

   /* code follows here */            // The vtableStub code

   void* operator new(size_t size, int code_size) throw();

   VtableStub(bool is_vtable_stub, int index)

         : _next(NULL), _is_vtable_stub(is_vtable_stub),

           _index(index), _ame_offset(-1), _npe_offset(-1) {}

   VtableStub* next() const                       { return _next; }

   int index() const                              { return _index; }

   static VMReg receiver_location()               { return _receiver_location; }

   void set_next(VtableStub* n)                   { _next = n; }

  public:

   address code_begin() const                     { return (address)(this + 1); }

   address code_end() const                       { return code_begin() + pd_code_size_limit(_is_vtable_stub); }

   address entry_point() const                    { return code_begin(); }

   static int entry_offset()                      { return sizeof(class VtableStub); }

   bool matches(bool is_vtable_stub, int index) const {

     return _index == index && _is_vtable_stub == is_vtable_stub;

   }

   bool contains(address pc) const                { return code_begin() <= pc && pc < code_end(); }

  private:

   void set_exception_points(address npe_addr, address ame_addr) {

     _npe_offset = npe_addr - code_begin();

     _ame_offset = ame_addr - code_begin();

     assert(is_abstract_method_error(ame_addr),   "offset must be correct");

     assert(is_null_pointer_exception(npe_addr),  "offset must be correct");

     assert(!is_abstract_method_error(npe_addr),  "offset must be correct");

     assert(!is_null_pointer_exception(ame_addr), "offset must be correct");

   }

   // platform-dependent routines

   static int  pd_code_size_limit(bool is_vtable_stub);

   static int  pd_code_alignment();

   // CNC: Removed because vtable stubs are now made with an ideal graph

   // static bool pd_disregard_arg_size();

   static void align_chunk() {

     uintptr_t off = (uintptr_t)( _chunk + sizeof(VtableStub) ) % pd_code_alignment();

     if (off != 0)  _chunk += pd_code_alignment() - off;

   }

  public:

   // Query

   bool is_itable_stub()                          { return !_is_vtable_stub; }

   bool is_vtable_stub()                          { return  _is_vtable_stub; }

   bool is_abstract_method_error(address epc)     { return epc == code_begin()+_ame_offset; }

   bool is_null_pointer_exception(address epc)    { return epc == code_begin()+_npe_offset; }

   void print_on(outputStream* st) const;

   void print() const                             { print_on(tty); }

 };

 // VtableStubs creates the code stubs for compiled calls through vtables.

 // There is one stub per (vtable index, args_size) pair, and the stubs are

 // never deallocated. They don't need to be GCed because they contain no oops.

 class VtableStubs : AllStatic {

  public:                                         // N must be public (some compilers need this for _table)

   enum {

     N    = 256,                                  // size of stub table; must be power of two

     mask = N - 1

   };

  private:

   static VtableStub* _table[N];                  // table of existing stubs

   static int         _number_of_vtable_stubs;    // number of stubs created so far (for statistics)

   static VtableStub* create_vtable_stub(int vtable_index);

   static VtableStub* create_itable_stub(int vtable_index);

   static VtableStub* lookup            (bool is_vtable_stub, int vtable_index);

   static void        enter             (bool is_vtable_stub, int vtable_index, VtableStub* s);

   static inline uint hash              (bool is_vtable_stub, int vtable_index);

   static address     find_stub         (bool is_vtable_stub, int vtable_index);

  public:

   static address     find_vtable_stub(int vtable_index) { return find_stub(true,  vtable_index); }

   static address     find_itable_stub(int itable_index) { return find_stub(false, itable_index); }

   static bool        is_entry_point(address pc);                     // is pc a vtable stub entry point?

   static bool        contains(address pc);                           // is pc within any stub?

   static VtableStub* stub_containing(address pc);                    // stub containing pc or NULL

   static int         number_of_vtable_stubs() { return _number_of_vtable_stubs; }

   static void        initialize();

   static void        vtable_stub_do(void f(VtableStub*));            // iterates over all vtable stubs

 };

 #endif // SHARE_VM_CODE_VTABLESTUBS_HPP