/*

 * Copyright (c) 1998, 2010, 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/debugInfoRec.hpp"

#include "code/scopeDesc.hpp"

#include "prims/jvmtiExport.hpp"

// Private definition.

// There is one DIR_Chunk for each scope and values array.

// A chunk can potentially be used more than once.

// We keep track of these chunks in order to detect

// repetition and enable sharing.

class DIR_Chunk {

  friend class DebugInformationRecorder;

  int  _offset; // location in the stream of this scope

  int  _length; // number of bytes in the stream

  int  _hash;   // hash of stream bytes (for quicker reuse)

  void* operator new(size_t ignore, DebugInformationRecorder* dir) {

    assert(ignore == sizeof(DIR_Chunk), "");

    if (dir->_next_chunk >= dir->_next_chunk_limit) {

      const int CHUNK = 100;

      dir->_next_chunk = NEW_RESOURCE_ARRAY(DIR_Chunk, CHUNK);

      dir->_next_chunk_limit = dir->_next_chunk + CHUNK;

    }

    return dir->_next_chunk++;

  }

  DIR_Chunk(int offset, int length, DebugInformationRecorder* dir) {

    _offset = offset;

    _length = length;

    unsigned int hash = 0;

    address p = dir->stream()->buffer() + _offset;

    for (int i = 0; i < length; i++) {

      if (i == 6)  break;

      hash *= 127;

      hash += p[i];

    }

    _hash = hash;

  }

  DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr,

                        int start_index,

                        DebugInformationRecorder* dir) {

    int end_index = arr->length();

    int hash = this->_hash, length = this->_length;

    address buf = dir->stream()->buffer();

    for (int i = end_index; --i >= start_index; ) {

      DIR_Chunk* that = arr->at(i);

      if (hash   == that->_hash &&

          length == that->_length &&

          0 == memcmp(buf + this->_offset, buf + that->_offset, length)) {

        return that;

      }

    }

    return NULL;

  }

};

static inline bool compute_recording_non_safepoints() {

  if (JvmtiExport::should_post_compiled_method_load()

      && FLAG_IS_DEFAULT(DebugNonSafepoints)) {

    // The default value of this flag is taken to be true,

    // if JVMTI is looking at nmethod codes.

    // We anticipate that JVMTI may wish to participate in profiling.

    return true;

  }

  // If the flag is set manually, use it, whether true or false.

  // Otherwise, if JVMTI is not in the picture, use the default setting.

  // (This is true in debug, just for the exercise, false in product mode.)

  return DebugNonSafepoints;

}

DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder)

  : _recording_non_safepoints(compute_recording_non_safepoints())

{

  _pcs_size   = 100;

  _pcs        = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size);

  _pcs_length = 0;

  _prev_safepoint_pc = PcDesc::lower_offset_limit;

  _stream = new DebugInfoWriteStream(this, 10 * K);

  // make sure that there is no stream_decode_offset that is zero

  _stream->write_byte((jbyte)0xFF);

  // make sure that we can distinguish the value "serialized_null" from offsets

  assert(_stream->position() > serialized_null, "sanity");

  _oop_recorder = oop_recorder;

  _all_chunks    = new GrowableArray<DIR_Chunk*>(300);

  _shared_chunks = new GrowableArray<DIR_Chunk*>(30);

  _next_chunk = _next_chunk_limit = NULL;

  add_new_pc_offset(PcDesc::lower_offset_limit);  // sentinel record

  debug_only(_recording_state = rs_null);

}

void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) {

  // !!!!! Preserve old style handling of oopmaps for now

  _oopmaps->add_gc_map(pc_offset, map);

}

void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) {

  assert(!_oop_recorder->is_complete(), "not frozen yet");

  // Store the new safepoint

  // Add the oop map

  add_oopmap(pc_offset, map);

  add_new_pc_offset(pc_offset);

  assert(_recording_state == rs_null, "nesting of recording calls");

  debug_only(_recording_state = rs_safepoint);

}

void DebugInformationRecorder::add_non_safepoint(int pc_offset) {

  assert(!_oop_recorder->is_complete(), "not frozen yet");

  assert(_recording_non_safepoints, "must be recording non-safepoints");

  add_new_pc_offset(pc_offset);

  assert(_recording_state == rs_null, "nesting of recording calls");

  debug_only(_recording_state = rs_non_safepoint);

}

void DebugInformationRecorder::add_new_pc_offset(int pc_offset) {

  assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset,

         "must specify a new, larger pc offset");

  // add the pcdesc

  if (_pcs_length == _pcs_size) {

    // Expand

    int     new_pcs_size = _pcs_size * 2;

    PcDesc* new_pcs      = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size);

    for (int index = 0; index < _pcs_length; index++) {

      new_pcs[index] = _pcs[index];

    }

    _pcs_size = new_pcs_size;

    _pcs      = new_pcs;

  }

  assert(_pcs_size > _pcs_length, "There must be room for after expanding");

  _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null,

                               DebugInformationRecorder::serialized_null);

}

int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) {

  if (monitors == NULL || monitors->is_empty()) return DebugInformationRecorder::serialized_null;

  assert(_recording_state == rs_safepoint, "must be recording a safepoint");

  int result = stream()->position();

  stream()->write_int(monitors->length());

  for (int index = 0; index < monitors->length(); index++) {

    monitors->at(index)->write_on(stream());

  }

  assert(result != serialized_null, "sanity");

  // (See comment below on DebugInformationRecorder::describe_scope.)

  int shared_result = find_sharable_decode_offset(result);

  if (shared_result != serialized_null) {

    stream()->set_position(result);

    result = shared_result;

  }

  return result;

}

int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) {

  if (values == NULL || values->is_empty()) return DebugInformationRecorder::serialized_null;

  assert(_recording_state == rs_safepoint, "must be recording a safepoint");

  int result = stream()->position();

  assert(result != serialized_null, "sanity");

  stream()->write_int(values->length());

  for (int index = 0; index < values->length(); index++) {

    values->at(index)->write_on(stream());

  }

  // (See comment below on DebugInformationRecorder::describe_scope.)

  int shared_result = find_sharable_decode_offset(result);

  if (shared_result != serialized_null) {

    stream()->set_position(result);

    result = shared_result;

  }

  return result;

}

#ifndef PRODUCT

// These variables are put into one block to reduce relocations

// and make it simpler to print from the debugger.

static

struct dir_stats_struct {

  int chunks_queried;

  int chunks_shared;

  int chunks_reshared;

  int chunks_elided;

  void print() {

    tty->print_cr("Debug Data Chunks: %d, shared %d+%d, non-SP's elided %d",

                  chunks_queried,

                  chunks_shared, chunks_reshared,

                  chunks_elided);

  }

} dir_stats;

#endif //PRODUCT

int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) {

  // Only pull this trick if non-safepoint recording

  // is enabled, for now.

  if (!recording_non_safepoints())

    return serialized_null;

  NOT_PRODUCT(++dir_stats.chunks_queried);

  int stream_length = stream()->position() - stream_offset;

  assert(stream_offset != serialized_null, "should not be null");

  assert(stream_length != 0, "should not be empty");

  DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this);

  // Look in previously shared scopes first:

  DIR_Chunk* ms = ns->find_match(_shared_chunks, 0, this);

  if (ms != NULL) {

    NOT_PRODUCT(++dir_stats.chunks_reshared);

    assert(ns+1 == _next_chunk, "");

    _next_chunk = ns;

    return ms->_offset;

  }

  // Look in recently encountered scopes next:

  const int MAX_RECENT = 50;

  int start_index = _all_chunks->length() - MAX_RECENT;

  if (start_index < 0)  start_index = 0;

  ms = ns->find_match(_all_chunks, start_index, this);

  if (ms != NULL) {

    NOT_PRODUCT(++dir_stats.chunks_shared);

    // Searching in _all_chunks is limited to a window,

    // but searching in _shared_chunks is unlimited.

    _shared_chunks->append(ms);

    assert(ns+1 == _next_chunk, "");

    _next_chunk = ns;

    return ms->_offset;

  }

  // No match.  Add this guy to the list, in hopes of future shares.

  _all_chunks->append(ns);

  return serialized_null;

}

// must call add_safepoint before: it sets PcDesc and this routine uses

// the last PcDesc set

void DebugInformationRecorder::describe_scope(int         pc_offset,

                                              ciMethod*   method,

                                              int         bci,

                                              bool        reexecute,

                                              bool        is_method_handle_invoke,

                                              bool        return_oop,

                                              DebugToken* locals,

                                              DebugToken* expressions,

                                              DebugToken* monitors) {

  assert(_recording_state != rs_null, "nesting of recording calls");

  PcDesc* last_pd = last_pc();

  assert(last_pd->pc_offset() == pc_offset, "must be last pc");

  int sender_stream_offset = last_pd->scope_decode_offset();

  // update the stream offset of current pc desc

  int stream_offset = stream()->position();

  last_pd->set_scope_decode_offset(stream_offset);

  // Record flags into pcDesc.

  last_pd->set_should_reexecute(reexecute);

  last_pd->set_is_method_handle_invoke(is_method_handle_invoke);

  last_pd->set_return_oop(return_oop);

  // serialize sender stream offest

  stream()->write_int(sender_stream_offset);

  // serialize scope

  jobject method_enc = (method == NULL)? NULL: method->constant_encoding();

  stream()->write_int(oop_recorder()->find_index(method_enc));

  stream()->write_bci(bci);

  assert(method == NULL ||

         (method->is_native() && bci == 0) ||

         (!method->is_native() && 0 <= bci && bci < method->code_size()) ||

         bci == -1, "illegal bci");

  // serialize the locals/expressions/monitors

  stream()->write_int((intptr_t) locals);

  stream()->write_int((intptr_t) expressions);

  stream()->write_int((intptr_t) monitors);

  // Here's a tricky bit.  We just wrote some bytes.

  // Wouldn't it be nice to find that we had already

  // written those same bytes somewhere else?

  // If we get lucky this way, reset the stream

  // and reuse the old bytes.  By the way, this

  // trick not only shares parent scopes, but also

  // compresses equivalent non-safepoint PcDescs.

  int shared_stream_offset = find_sharable_decode_offset(stream_offset);

  if (shared_stream_offset != serialized_null) {

    stream()->set_position(stream_offset);

    last_pd->set_scope_decode_offset(shared_stream_offset);

  }

}

void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {

  guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");

  PcDesc* last_pd = &_pcs[_pcs_length-1];

  if (objects != NULL) {

    for (int i = objects->length() - 1; i >= 0; i--) {

      ((ObjectValue*) objects->at(i))->set_visited(false);

    }

  }

  int offset = serialize_scope_values(objects);

  last_pd->set_obj_decode_offset(offset);

}

void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {

  assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),

         "nesting of recording calls");

  debug_only(_recording_state = rs_null);

  // Try to compress away an equivalent non-safepoint predecessor.

  // (This only works because we have previously recognized redundant

  // scope trees and made them use a common scope_decode_offset.)

  if (_pcs_length >= 2 && recording_non_safepoints()) {

    PcDesc* last = last_pc();

    PcDesc* prev = prev_pc();

    // If prev is (a) not a safepoint and (b) has the same

    // stream pointer, then it can be coalesced into the last.

    // This is valid because non-safepoints are only sought

    // with pc_desc_near, which (when it misses prev) will

    // search forward until it finds last.

    // In addition, it does not matter if the last PcDesc

    // is for a safepoint or not.

    if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {

      assert(prev == last-1, "sane");

      prev->set_pc_offset(pc_offset);

      _pcs_length -= 1;

      NOT_PRODUCT(++dir_stats.chunks_elided);

    }

  }

  // We have just recorded this safepoint.

  // Remember it in case the previous paragraph needs to know.

  if (is_safepoint) {

    _prev_safepoint_pc = pc_offset;

  }

}

DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {

  assert(!_oop_recorder->is_complete(), "not frozen yet");

  return (DebugToken*) (intptr_t) serialize_scope_values(values);

}

DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {

  assert(!_oop_recorder->is_complete(), "not frozen yet");

  return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);

}

int DebugInformationRecorder::data_size() {

  debug_only(_oop_recorder->oop_size());  // mark it "frozen" for asserts

  return _stream->position();

}

int DebugInformationRecorder::pcs_size() {

  debug_only(_oop_recorder->oop_size());  // mark it "frozen" for asserts

  if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)

    add_new_pc_offset(PcDesc::upper_offset_limit);

  return _pcs_length * sizeof(PcDesc);

}

void DebugInformationRecorder::copy_to(nmethod* nm) {

  nm->copy_scopes_data(stream()->buffer(), stream()->position());

  nm->copy_scopes_pcs(_pcs, _pcs_length);

}

void DebugInformationRecorder::verify(const nmethod* code) {

  Unimplemented();

}

#ifndef PRODUCT

void DebugInformationRecorder::print_statistics() {

  dir_stats.print();

}

#endif //PRODUCT