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 /*

  * Copyright (c) 2004, 2012, 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 "asm/macroAssembler.inline.hpp"

 #include "asm/codeBuffer.hpp"

 #include "memory/metaspaceShared.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()->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 relationship

 // 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 MetaspaceShared::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;

   guarantee(*md_top <= md_end, "Insufficient space for vtables.");

   // 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();

       __ save(SP, -256, SP);

       int offset = (i << 8) + j;

       Register src = G0;

       if (!Assembler::is_simm13(offset)) {

         __ sethi(offset, L0);

         src = L0;

         offset = offset & ((1 << 10) - 1);

       }

       __ brx(Assembler::always, false, Assembler::pt, common_code);

       // Load L0 with a value indicating vtable/offset pair.

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

       // -- bits[13..8]  (6 bits) which virtual method table?

       __ delayed()->or3(src, offset, L0);

     }

   }

   __ bind(common_code);

   // Expecting to be called with the "this" pointer in O0/I0 (where

   // "this" is a Klass object).  In addition, L0 was set (above) to

   // identify the method and table.

   // Look up the correct vtable pointer.

   __ set((intptr_t)vtbl_list, L2);      // L2 = address of new vtable list.

   __ srl(L0, 8, L3);                    // Isolate L3 = vtable identifier.

   __ sll(L3, LogBytesPerWord, L3);

   __ ld_ptr(L2, L3, L3);                // L3 = new (correct) vtable pointer.

   __ st_ptr(L3, Address(I0, 0));        // Save correct vtable ptr in entry.

   // Restore registers and jump to the correct method;

   __ and3(L0, 255, L4);                 // Isolate L3 = method offset;.

   __ sll(L4, LogBytesPerWord, L4);

   __ ld_ptr(L3, L4, L4);                // Get address of correct virtual method

   __ jmpl(L4, 0, G0);                   // Jump to correct method.

   __ delayed()->restore();              // Restore registers.

   __ flush();

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

   guarantee(*mc_top <= mc_end, "Insufficient space for method wrappers.");

 }