/*

 * 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 "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.");

}