/*

 * Copyright (c) 2004, 2012, Oracle and/or its affiliates. All rights reserved.

 * Copyright (c) 2014, Red Hat Inc. 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.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->

extern "C" {

  void aarch64_prolog(void);

}

void MetaspaceShared::generate_vtable_methods(void** vtbl_list,

                                                   void** vtable,

                                                   char** md_top,

                                                   char* md_end,

                                                   char** mc_top,

                                                   char* mc_end) {

#ifdef BUILTIN_SIM

  // Write a dummy word to the writable shared metaspace.

  // MetaspaceShared::initialize_shared_spaces will fill it with the

  // address of aarch64_prolog().

  address *prolog_ptr = (address*)*md_top;

  *(intptr_t *)(*md_top) = (intptr_t)0;

  (*md_top) += sizeof(intptr_t);

#endif

  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();

      // We're called directly from C code.

#ifdef BUILTIN_SIM

      __ c_stub_prolog(8, 0, MacroAssembler::ret_type_integral, prolog_ptr);

#endif

      // Load rscratch1 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?

      __ mov(rscratch1, (i << 8) + j);

      __ b(common_code);

    }

  }

  __ bind(common_code);

  Register tmp0 = r10, tmp1 = r11;       // AAPCS64 temporary registers

  __ enter();

  __ lsr(tmp0, rscratch1, 8);            // isolate vtable identifier.

  __ mov(tmp1, (address)vtbl_list);      // address of list of vtable pointers.

  __ ldr(tmp1, Address(tmp1, tmp0, Address::lsl(LogBytesPerWord))); // get correct vtable pointer.

  __ str(tmp1, Address(c_rarg0));        // update vtable pointer in obj.

  __ add(rscratch1, tmp1, rscratch1, ext::uxtb, LogBytesPerWord); // address of real method pointer.

  __ ldr(rscratch1, Address(rscratch1)); // get real method pointer.

  __ blrt(rscratch1, 8, 0, 1);           // jump to the real method.

  __ leave();

  __ ret(lr);

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

}

#ifdef BUILTIN_SIM

void MetaspaceShared::relocate_vtbl_list(char **buffer) {

  void **sim_entry = (void**)*buffer;

  *sim_entry = (void*)aarch64_prolog;

  *buffer += sizeof(intptr_t);

}

#endif