/*

 * 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 "code/codeCache.hpp"

#include "code/compiledIC.hpp"

#include "code/icBuffer.hpp"

#include "code/nmethod.hpp"

#include "code/scopeDesc.hpp"

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

#include "interpreter/interpreter.hpp"

#include "interpreter/linkResolver.hpp"

#include "memory/resourceArea.hpp"

#include "memory/universe.inline.hpp"

#include "oops/method.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/stubRoutines.hpp"

DEF_STUB_INTERFACE(ICStub);

StubQueue* InlineCacheBuffer::_buffer    = NULL;

ICStub*    InlineCacheBuffer::_next_stub = NULL;

CompiledICHolder* InlineCacheBuffer::_pending_released = NULL;

int InlineCacheBuffer::_pending_count = 0;

void ICStub::finalize() {

  if (!is_empty()) {

    ResourceMark rm;

    CompiledIC *ic = CompiledIC_at(CodeCache::find_nmethod(ic_site()), ic_site());

    assert(CodeCache::find_nmethod(ic->instruction_address()) != NULL, "inline cache in non-nmethod?");

    assert(this == ICStub_from_destination_address(ic->stub_address()), "wrong owner of ic buffer");

    ic->set_ic_destination_and_value(destination(), cached_value());

  }

}

address ICStub::destination() const {

  return InlineCacheBuffer::ic_buffer_entry_point(code_begin());

}

void* ICStub::cached_value() const {

  return InlineCacheBuffer::ic_buffer_cached_value(code_begin());

}

void ICStub::set_stub(CompiledIC *ic, void* cached_val, address dest_addr) {

  // We cannot store a pointer to the 'ic' object, since it is resource allocated. Instead we

  // store the location of the inline cache. Then we have enough information recreate the CompiledIC

  // object when we need to remove the stub.

  _ic_site = ic->instruction_address();

  // Assemble new stub

  InlineCacheBuffer::assemble_ic_buffer_code(code_begin(), cached_val, dest_addr);

  assert(destination() == dest_addr,   "can recover destination");

  assert(cached_value() == cached_val, "can recover destination");

}

void ICStub::clear() {

  if (CompiledIC::is_icholder_entry(destination())) {

    InlineCacheBuffer::queue_for_release((CompiledICHolder*)cached_value());

  }

  _ic_site = NULL;

}

#ifndef PRODUCT

// anybody calling to this stub will trap

void ICStub::verify() {

}

void ICStub::print() {

  tty->print_cr("ICStub: site: " INTPTR_FORMAT, p2i(_ic_site));

}

#endif

//-----------------------------------------------------------------------------------------------

// Implementation of InlineCacheBuffer

void InlineCacheBuffer::init_next_stub() {

  ICStub* ic_stub = (ICStub*)buffer()->request_committed (ic_stub_code_size());

  assert (ic_stub != NULL, "no room for a single stub");

  set_next_stub(ic_stub);

}

void InlineCacheBuffer::initialize() {

  if (_buffer != NULL) return; // already initialized

  _buffer = new StubQueue(new ICStubInterface, 10*K, InlineCacheBuffer_lock, "InlineCacheBuffer");

  assert (_buffer != NULL, "cannot allocate InlineCacheBuffer");

  init_next_stub();

}

ICStub* InlineCacheBuffer::new_ic_stub() {

  while (true) {

    ICStub* ic_stub = (ICStub*)buffer()->request_committed(ic_stub_code_size());

    if (ic_stub != NULL) {

      return ic_stub;

    }

    // we ran out of inline cache buffer space; must enter safepoint.

    // We do this by forcing a safepoint

    EXCEPTION_MARK;

    VM_ForceSafepoint vfs;

    VMThread::execute(&vfs);

    // We could potential get an async. exception at this point.

    // In that case we will rethrow it to ourselvs.

    if (HAS_PENDING_EXCEPTION) {

      oop exception = PENDING_EXCEPTION;

      CLEAR_PENDING_EXCEPTION;

      Thread::send_async_exception(JavaThread::current()->threadObj(), exception);

    }

  }

  ShouldNotReachHere();

  return NULL;

}

void InlineCacheBuffer::update_inline_caches() {

  if (buffer()->number_of_stubs() > 1) {

    if (TraceICBuffer) {

      tty->print_cr("[updating inline caches with %d stubs]", buffer()->number_of_stubs());

    }

    buffer()->remove_all();

    init_next_stub();

  }

  release_pending_icholders();

}

bool InlineCacheBuffer::contains(address instruction_address) {

  return buffer()->contains(instruction_address);

}

bool InlineCacheBuffer::is_empty() {

  return buffer()->number_of_stubs() == 1;    // always has sentinel

}

void InlineCacheBuffer_init() {

  InlineCacheBuffer::initialize();

}

void InlineCacheBuffer::create_transition_stub(CompiledIC *ic, void* cached_value, address entry) {

  assert(!SafepointSynchronize::is_at_safepoint(), "should not be called during a safepoint");

  assert (CompiledIC_lock->is_locked(), "");

  if (TraceICBuffer) {

    tty->print_cr("  create transition stub for " INTPTR_FORMAT " destination " INTPTR_FORMAT " cached value " INTPTR_FORMAT,

                  p2i(ic->instruction_address()), p2i(entry), p2i(cached_value));

  }

  // If an transition stub is already associate with the inline cache, then we remove the association.

  if (ic->is_in_transition_state()) {

    ICStub* old_stub = ICStub_from_destination_address(ic->stub_address());

    old_stub->clear();

  }

  // allocate and initialize new "out-of-line" inline-cache

  ICStub* ic_stub = get_next_stub();

  ic_stub->set_stub(ic, cached_value, entry);

  // Update inline cache in nmethod to point to new "out-of-line" allocated inline cache

  ic->set_ic_destination(ic_stub);

  set_next_stub(new_ic_stub()); // can cause safepoint synchronization

}

address InlineCacheBuffer::ic_destination_for(CompiledIC *ic) {

  ICStub* stub = ICStub_from_destination_address(ic->stub_address());

  return stub->destination();

}

void* InlineCacheBuffer::cached_value_for(CompiledIC *ic) {

  ICStub* stub = ICStub_from_destination_address(ic->stub_address());

  return stub->cached_value();

}

// Free CompiledICHolder*s that are no longer in use

void InlineCacheBuffer::release_pending_icholders() {

  assert(SafepointSynchronize::is_at_safepoint(), "should only be called during a safepoint");

  CompiledICHolder* holder = _pending_released;

  _pending_released = NULL;

  while (holder != NULL) {

    CompiledICHolder* next = holder->next();

    delete holder;

    holder = next;

    _pending_count--;

  }

  assert(_pending_count == 0, "wrong count");

}

// Enqueue this icholder for release during the next safepoint.  It's

// not safe to free them until them since they might be visible to

// another thread.

void InlineCacheBuffer::queue_for_release(CompiledICHolder* icholder) {

  MutexLockerEx mex(InlineCacheBuffer_lock);

  icholder->set_next(_pending_released);

  _pending_released = icholder;

  _pending_count++;

  if (TraceICBuffer) {

    tty->print_cr("enqueueing icholder " INTPTR_FORMAT " to be freed", p2i(icholder));

  }

}