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 /*

  * Copyright (c) 2004, 2010, 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

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "assembler_x86.inline.hpp"

 #include "memory/compactingPermGenGen.hpp"

 #include "memory/generation.inline.hpp"

 #include "memory/space.inline.hpp"

 // Generate the self-patching vtable method:

 //

 // This method will be called (as any other Klass virtual method) with

 // the Klass itself as the first argument.  Example:

 //

 //      oop obj;

 //      int size = obj->klass()->klass_part()->oop_size(this);

 //

 // for which the virtual method call is Klass::oop_size();

 //

 // The dummy method is called with the Klass object as the first

 // operand, and an object as the second argument.

 //

 //=====================================================================

 // All of the dummy methods in the vtable are essentially identical,

 // differing only by an ordinal constant, and they bear no releationship

 // to the original method which the caller intended. Also, there needs

 // to be 'vtbl_list_size' instances of the vtable in order to

 // differentiate between the 'vtable_list_size' original Klass objects.

 #define __ masm->

 void CompactingPermGenGen::generate_vtable_methods(void** vtbl_list,

                                                    void** vtable,

                                                    char** md_top,

                                                    char* md_end,

                                                    char** mc_top,

                                                    char* mc_end) {

   intptr_t vtable_bytes = (num_virtuals * vtbl_list_size) * sizeof(void*);

   *(intptr_t *)(*md_top) = vtable_bytes;

   *md_top += sizeof(intptr_t);

   void** dummy_vtable = (void**)*md_top;

   *vtable = dummy_vtable;

   *md_top += vtable_bytes;

   // Get ready to generate dummy methods.

   CodeBuffer cb((unsigned char*)*mc_top, mc_end - *mc_top);

   MacroAssembler* masm = new MacroAssembler(&cb);

   Label common_code;

   for (int i = 0; i < vtbl_list_size; ++i) {

     for (int j = 0; j < num_virtuals; ++j) {

       dummy_vtable[num_virtuals * i + j] = (void*)masm->pc();

       // Load eax with a value indicating vtable/offset pair.

       // -- bits[ 7..0]  (8 bits) which virtual method in table?

       // -- bits[12..8]  (5 bits) which virtual method table?

       // -- must fit in 13-bit instruction immediate field.

       __ movl(rax, (i << 8) + j);

       __ jmp(common_code);

     }

   }

   __ bind(common_code);

   // Expecting to be called with "thiscall" convections -- the arguments

   // are on the stack and the "this" pointer is in c_rarg0. In addition, rax

   // was set (above) to the offset of the method in the table.

   __ push(c_rarg1);                     // save & free register

   __ push(c_rarg0);                     // save "this"

   __ mov(c_rarg0, rax);

   __ shrptr(c_rarg0, 8);                // isolate vtable identifier.

   __ shlptr(c_rarg0, LogBytesPerWord);

   __ lea(c_rarg1, ExternalAddress((address)vtbl_list)); // ptr to correct vtable list.

   __ addptr(c_rarg1, c_rarg0);          // ptr to list entry.

   __ movptr(c_rarg1, Address(c_rarg1, 0));      // get correct vtable address.

   __ pop(c_rarg0);                      // restore "this"

   __ movptr(Address(c_rarg0, 0), c_rarg1);      // update vtable pointer.

   __ andptr(rax, 0x00ff);                       // isolate vtable method index

   __ shlptr(rax, LogBytesPerWord);

   __ addptr(rax, c_rarg1);              // address of real method pointer.

   __ pop(c_rarg1);                      // restore register.

   __ movptr(rax, Address(rax, 0));      // get real method pointer.

   __ jmp(rax);                          // jump to the real method.

   __ flush();

   *mc_top = (char*)__ pc();

 }