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 /*

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  * 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_STUBS_HPP

 #define SHARE_VM_CODE_STUBS_HPP

 #include "memory/allocation.hpp"

 #ifdef TARGET_OS_FAMILY_linux

 # include "os_linux.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_solaris

 # include "os_solaris.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_windows

 # include "os_windows.inline.hpp"

 #endif

 // The classes in this file provide a simple framework for the

 // management of little pieces of machine code - or stubs -

 // created on the fly and frequently discarded. In this frame-

 // work stubs are stored in a queue.

 // Stub serves as abstract base class. A concrete stub

 // implementation is a subclass of Stub, implementing

 // all (non-virtual!) functions required sketched out

 // in the Stub class.

 //

 // A concrete stub layout may look like this (both data

 // and code sections could be empty as well):

 //

 //                ________

 // stub       -->|        | <--+

 //               |  data  |    |

 //               |________|    |

 // code_begin -->|        |    |

 //               |        |    |

 //               |  code  |    | size

 //               |        |    |

 //               |________|    |

 // code_end   -->|        |    |

 //               |  data  |    |

 //               |________|    |

 //                          <--+

 class Stub VALUE_OBJ_CLASS_SPEC {

  public:

   // Initialization/finalization

   void    initialize(int size)                   { ShouldNotCallThis(); }                // called to initialize/specify the stub's size

   void    finalize()                             { ShouldNotCallThis(); }                // called before the stub is deallocated

   // General info/converters

   int     size() const                           { ShouldNotCallThis(); return 0; }      // must return the size provided by initialize

   static  int code_size_to_size(int code_size)   { ShouldNotCallThis(); return 0; }      // computes the size given the code size

   // Code info

   address code_begin() const                     { ShouldNotCallThis(); return NULL; }   // points to the first byte of    the code

   address code_end() const                       { ShouldNotCallThis(); return NULL; }   // points to the first byte after the code

   // Debugging

   void    verify()                               { ShouldNotCallThis(); }                // verifies the Stub

   void    print()                                { ShouldNotCallThis(); }                // prints some information about the stub

 };

 // A stub interface defines the interface between a stub queue

 // and the stubs it queues. In order to avoid a vtable and

 // (and thus the extra word) in each stub, a concrete stub

 // interface object is created and associated with a stub

 // buffer which in turn uses the stub interface to interact

 // with its stubs.

 //

 // StubInterface serves as an abstract base class. A concrete

 // stub interface implementation is a subclass of StubInterface,

 // forwarding its virtual function calls to non-virtual calls

 // of the concrete stub (see also macro below). There's exactly

 // one stub interface instance required per stub queue.

 class StubInterface: public CHeapObj {

  public:

   // Initialization/finalization

   virtual void    initialize(Stub* self, int size)         = 0; // called after creation (called twice if allocated via (request, commit))

   virtual void    finalize(Stub* self)                     = 0; // called before deallocation

   // General info/converters

   virtual int     size(Stub* self) const                   = 0; // the total size of the stub in bytes (must be a multiple of CodeEntryAlignment)

   virtual int     code_size_to_size(int code_size) const   = 0; // computes the total stub size in bytes given the code size in bytes

   // Code info

   virtual address code_begin(Stub* self) const             = 0; // points to the first code byte

   virtual address code_end(Stub* self) const               = 0; // points to the first byte after the code

   // Debugging

   virtual void    verify(Stub* self)                       = 0; // verifies the stub

   virtual void    print(Stub* self)                        = 0; // prints information about the stub

 };

 // DEF_STUB_INTERFACE is used to create a concrete stub interface

 // class, forwarding stub interface calls to the corresponding

 // stub calls.

 #define DEF_STUB_INTERFACE(stub)                           \

   class stub##Interface: public StubInterface {            \

    private:                                                \

     static stub*    cast(Stub* self)                       { return (stub*)self; }                 \

                                                            \

    public:                                                 \

     /* Initialization/finalization */                      \

     virtual void    initialize(Stub* self, int size)       { cast(self)->initialize(size); }       \

     virtual void    finalize(Stub* self)                   { cast(self)->finalize(); }             \

                                                            \

     /* General info */                                     \

     virtual int     size(Stub* self) const                 { return cast(self)->size(); }          \

     virtual int     code_size_to_size(int code_size) const { return stub::code_size_to_size(code_size); } \

                                                            \

     /* Code info */                                        \

     virtual address code_begin(Stub* self) const           { return cast(self)->code_begin(); }    \

     virtual address code_end(Stub* self) const             { return cast(self)->code_end(); }      \

                                                            \

     /* Debugging */                                        \

     virtual void    verify(Stub* self)                     { cast(self)->verify(); }               \

     virtual void    print(Stub* self)                      { cast(self)->print(); }                \

   };

 // A StubQueue maintains a queue of stubs.

 // Note: All sizes (spaces) are given in bytes.

 class StubQueue: public CHeapObj {

   friend class VMStructs;

  private:

   StubInterface* _stub_interface;                // the interface prototype

   address        _stub_buffer;                   // where all stubs are stored

   int            _buffer_size;                   // the buffer size in bytes

   int            _buffer_limit;                  // the (byte) index of the actual buffer limit (_buffer_limit <= _buffer_size)

   int            _queue_begin;                   // the (byte) index of the first queue entry (word-aligned)

   int            _queue_end;                     // the (byte) index of the first entry after the queue (word-aligned)

   int            _number_of_stubs;               // the number of buffered stubs

   Mutex* const   _mutex;                         // the lock used for a (request, commit) transaction

   void  check_index(int i) const                 { assert(0 <= i && i < _buffer_limit && i % CodeEntryAlignment == 0, "illegal index"); }

   bool  is_contiguous() const                    { return _queue_begin <= _queue_end; }

   int   index_of(Stub* s) const                  { int i = (address)s - _stub_buffer; check_index(i); return i; }

   Stub* stub_at(int i) const                     { check_index(i); return (Stub*)(_stub_buffer + i); }

   Stub* current_stub() const                     { return stub_at(_queue_end); }

   // Stub functionality accessed via interface

   void  stub_initialize(Stub* s, int size)       { assert(size % CodeEntryAlignment == 0, "size not aligned"); _stub_interface->initialize(s, size); }

   void  stub_finalize(Stub* s)                   { _stub_interface->finalize(s); }

   int   stub_size(Stub* s) const                 { return _stub_interface->size(s); }

   bool  stub_contains(Stub* s, address pc) const { return _stub_interface->code_begin(s) <= pc && pc < _stub_interface->code_end(s); }

   int   stub_code_size_to_size(int code_size) const { return _stub_interface->code_size_to_size(code_size); }

   void  stub_verify(Stub* s)                     { _stub_interface->verify(s); }

   void  stub_print(Stub* s)                      { _stub_interface->print(s); }

   static void register_queue(StubQueue*);

  public:

   StubQueue(StubInterface* stub_interface, int buffer_size, Mutex* lock,

             const char* name);

   ~StubQueue();

   // General queue info

   bool  is_empty() const                         { return _queue_begin == _queue_end; }

   int   total_space() const                      { return _buffer_size - 1; }

   int   available_space() const                  { int d = _queue_begin - _queue_end - 1; return d < 0 ? d + _buffer_size : d; }

   int   used_space() const                       { return total_space() - available_space(); }

   int   number_of_stubs() const                  { return _number_of_stubs; }

   bool  contains(address pc) const               { return _stub_buffer <= pc && pc < _stub_buffer + _buffer_limit; }

   Stub* stub_containing(address pc) const;

   address code_start() const                     { return _stub_buffer; }

   address code_end() const                       { return _stub_buffer + _buffer_limit; }

   // Stub allocation (atomic transactions)

   Stub* request_committed(int code_size);        // request a stub that provides exactly code_size space for code

   Stub* request(int requested_code_size);        // request a stub with a (maximum) code space - locks the queue

   void  commit (int committed_code_size);        // commit the previously requested stub - unlocks the queue

   // Stub deallocation

   void  remove_first();                          // remove the first stub in the queue

   void  remove_first(int n);                     // remove the first n stubs in the queue

   void  remove_all();                            // remove all stubs in the queue

   // Iteration

   static void queues_do(void f(StubQueue* s));   // call f with each StubQueue

   void  stubs_do(void f(Stub* s));               // call f with all stubs

   Stub* first() const                            { return number_of_stubs() > 0 ? stub_at(_queue_begin) : NULL; }

   Stub* next(Stub* s) const                      { int i = index_of(s) + stub_size(s);

                                                    if (i == _buffer_limit) i = 0;

                                                    return (i == _queue_end) ? NULL : stub_at(i);

                                                  }

   address stub_code_begin(Stub* s) const         { return _stub_interface->code_begin(s); }

   address stub_code_end(Stub* s) const           { return _stub_interface->code_end(s);   }

   // Debugging/printing

   void  verify();                                // verifies the stub queue

   void  print();                                 // prints information about the stub queue

 };

 #endif // SHARE_VM_CODE_STUBS_HPP