/*

 * Copyright (c) 1997, 2015, 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.hpp"

#include "asm/macroAssembler.inline.hpp"

#include "code/icBuffer.hpp"

#include "gc/shared/collectedHeap.inline.hpp"

#include "interpreter/bytecodes.hpp"

#include "memory/resourceArea.hpp"

#include "nativeInst_x86.hpp"

#include "oops/oop.inline.hpp"

int InlineCacheBuffer::ic_stub_code_size() {

  // Worst case, if destination is not a near call:

  // lea rax, lit1

  // lea scratch, lit2

  // jmp scratch

  // Best case

  // lea rax, lit1

  // jmp lit2

  int best = NativeMovConstReg::instruction_size + NativeJump::instruction_size;

  int worst = 2 * NativeMovConstReg::instruction_size + 3;

  return MAX2(best, worst);

}

void InlineCacheBuffer::assemble_ic_buffer_code(address code_begin, void* cached_value, address entry_point) {

  ResourceMark rm;

  CodeBuffer      code(code_begin, ic_stub_code_size());

  MacroAssembler* masm            = new MacroAssembler(&code);

  // note: even though the code contains an embedded value, we do not need reloc info

  // because

  // (1) the value is old (i.e., doesn't matter for scavenges)

  // (2) these ICStubs are removed *before* a GC happens, so the roots disappear

  // assert(cached_value == NULL || cached_oop->is_perm(), "must be perm oop");

  masm->lea(rax, AddressLiteral((address) cached_value, relocInfo::metadata_type));

  masm->jump(ExternalAddress(entry_point));

}

address InlineCacheBuffer::ic_buffer_entry_point(address code_begin) {

  NativeMovConstReg* move = nativeMovConstReg_at(code_begin);   // creation also verifies the object

  address jmp = move->next_instruction_address();

  NativeInstruction* ni = nativeInstruction_at(jmp);

  if (ni->is_jump()) {

    NativeJump*        jump = nativeJump_at(jmp);

    return jump->jump_destination();

  } else {

    assert(ni->is_far_jump(), "unexpected instruction");

    NativeFarJump*     jump = nativeFarJump_at(jmp);

    return jump->jump_destination();

  }

}

void* InlineCacheBuffer::ic_buffer_cached_value(address code_begin) {

  // creation also verifies the object

  NativeMovConstReg* move = nativeMovConstReg_at(code_begin);

  // Verifies the jump

  address jmp = move->next_instruction_address();

  NativeInstruction* ni = nativeInstruction_at(jmp);

  if (ni->is_jump()) {

    NativeJump*        jump = nativeJump_at(jmp);

  } else {

    assert(ni->is_far_jump(), "unexpected instruction");

    NativeFarJump*     jump = nativeFarJump_at(jmp);

  }

  void* o = (void*)move->data();

  return o;

}