jdk

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/*
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 * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "code/debugInfoRec.hpp"
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#include "code/scopeDesc.hpp"
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#include "compiler/oopMap.hpp"
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#include "prims/jvmtiExport.hpp"
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#include "runtime/globals_extension.hpp"
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// Private definition.
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// There is one DIR_Chunk for each scope and values array.
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// A chunk can potentially be used more than once.
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// We keep track of these chunks in order to detect
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// repetition and enable sharing.
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class DIR_Chunk {
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private:
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  int  _offset; // location in the stream of this scope
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  int  _length; // number of bytes in the stream
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  int  _hash;   // hash of stream bytes (for quicker reuse)
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  DebugInformationRecorder* _DIR;
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public:
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  int offset() { return _offset; }
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  void* operator new(size_t ignore, DebugInformationRecorder* dir) throw() {
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    assert(ignore == sizeof(DIR_Chunk), "");
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    if (dir->_next_chunk >= dir->_next_chunk_limit) {
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      const int CHUNK = 100;
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      dir->_next_chunk = NEW_RESOURCE_ARRAY(DIR_Chunk, CHUNK);
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      dir->_next_chunk_limit = dir->_next_chunk + CHUNK;
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    }
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    return dir->_next_chunk++;
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  }
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  DIR_Chunk(int offset, int length, DebugInformationRecorder* dir) {
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    _offset = offset;
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    _length = length;
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    _DIR = dir;
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    unsigned int hash = 0;
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    address p = dir->stream()->buffer() + _offset;
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    for (int i = 0; i < length; i++) {
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      if (i == 6)  break;
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      hash *= 127;
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      hash += p[i];
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    }
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    _hash = hash;
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  }
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  DIR_Chunk* find_match(GrowableArray<DIR_Chunk*>* arr,
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                        int start_index,
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                        DebugInformationRecorder* dir) {
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    int end_index = arr->length();
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    int hash = this->_hash, length = this->_length;
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    address buf = dir->stream()->buffer();
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    for (int i = end_index; --i >= start_index; ) {
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      DIR_Chunk* that = arr->at(i);
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      if (hash   == that->_hash &&
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          length == that->_length &&
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          0 == memcmp(buf + this->_offset, buf + that->_offset, length)) {
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        return that;
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      }
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    }
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    return nullptr;
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  }
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  static int compare(DIR_Chunk* const & a, DIR_Chunk* const & b) {
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    if (b->_hash > a->_hash) {
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      return 1;
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    }
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    if (b->_hash < a->_hash) {
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      return -1;
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    }
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    if (b->_length > a->_length) {
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      return 1;
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    }
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    if (b->_length < a->_length) {
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      return -1;
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    }
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    address buf = a->_DIR->stream()->buffer();
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    return memcmp(buf + b->_offset, buf + a->_offset, a->_length);
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  }
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};
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static inline bool compute_recording_non_safepoints() {
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  if (JvmtiExport::should_post_compiled_method_load()
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      && FLAG_IS_DEFAULT(DebugNonSafepoints)) {
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    // The default value of this flag is taken to be true,
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    // if JVMTI is looking at nmethod codes.
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    // We anticipate that JVMTI may wish to participate in profiling.
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    return true;
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  }
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  // If the flag is set manually, use it, whether true or false.
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  // Otherwise, if JVMTI is not in the picture, use the default setting.
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  // (This is true in debug, just for the exercise, false in product mode.)
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  return DebugNonSafepoints;
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}
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DebugInformationRecorder::DebugInformationRecorder(OopRecorder* oop_recorder)
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  : _recording_non_safepoints(compute_recording_non_safepoints())
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{
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  _pcs_size   = 100;
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  _pcs        = NEW_RESOURCE_ARRAY(PcDesc, _pcs_size);
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  _pcs_length = 0;
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  _prev_safepoint_pc = PcDesc::lower_offset_limit;
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  _stream = new DebugInfoWriteStream(this, 10 * K);
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  // make sure that there is no stream_decode_offset that is zero
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  _stream->write_byte((jbyte)0xFF);
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  // make sure that we can distinguish the value "serialized_null" from offsets
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  assert(_stream->position() > serialized_null, "sanity");
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  _oop_recorder = oop_recorder;
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  _all_chunks    = new GrowableArray<DIR_Chunk*>(300);
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  _next_chunk = _next_chunk_limit = nullptr;
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  add_new_pc_offset(PcDesc::lower_offset_limit);  // sentinel record
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  debug_only(_recording_state = rs_null);
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}
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void DebugInformationRecorder::add_oopmap(int pc_offset, OopMap* map) {
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  // !!!!! Preserve old style handling of oopmaps for now
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  _oopmaps->add_gc_map(pc_offset, map);
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}
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void DebugInformationRecorder::add_safepoint(int pc_offset, OopMap* map) {
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  assert(!_oop_recorder->is_complete(), "not frozen yet");
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  // Store the new safepoint
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  // Add the oop map
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  add_oopmap(pc_offset, map);
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  add_new_pc_offset(pc_offset);
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  assert(_recording_state == rs_null, "nesting of recording calls");
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  debug_only(_recording_state = rs_safepoint);
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}
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void DebugInformationRecorder::add_non_safepoint(int pc_offset) {
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  assert(!_oop_recorder->is_complete(), "not frozen yet");
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  assert(_recording_non_safepoints, "must be recording non-safepoints");
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  add_new_pc_offset(pc_offset);
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  assert(_recording_state == rs_null, "nesting of recording calls");
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  debug_only(_recording_state = rs_non_safepoint);
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}
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void DebugInformationRecorder::add_new_pc_offset(int pc_offset) {
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  assert(_pcs_length == 0 || last_pc()->pc_offset() < pc_offset,
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         "must specify a new, larger pc offset: %d >= %d", last_pc()->pc_offset(), pc_offset);
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  // add the pcdesc
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  if (_pcs_length == _pcs_size) {
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    // Expand
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    int     new_pcs_size = _pcs_size * 2;
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    PcDesc* new_pcs      = NEW_RESOURCE_ARRAY(PcDesc, new_pcs_size);
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    for (int index = 0; index < _pcs_length; index++) {
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      new_pcs[index] = _pcs[index];
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    }
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    _pcs_size = new_pcs_size;
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    _pcs      = new_pcs;
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  }
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  assert(_pcs_size > _pcs_length, "There must be room for after expanding");
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  _pcs[_pcs_length++] = PcDesc(pc_offset, DebugInformationRecorder::serialized_null,
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                               DebugInformationRecorder::serialized_null);
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}
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int DebugInformationRecorder::serialize_monitor_values(GrowableArray<MonitorValue*>* monitors) {
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  if (monitors == nullptr || monitors->is_empty()) return DebugInformationRecorder::serialized_null;
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  assert(_recording_state == rs_safepoint, "must be recording a safepoint");
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  int result = stream()->position();
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  stream()->write_int(monitors->length());
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  for (int index = 0; index < monitors->length(); index++) {
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    monitors->at(index)->write_on(stream());
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  }
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  assert(result != serialized_null, "sanity");
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  // (See comment below on DebugInformationRecorder::describe_scope.)
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  int shared_result = find_sharable_decode_offset(result);
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  if (shared_result != serialized_null) {
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    stream()->set_position(result);
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    result = shared_result;
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  }
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  return result;
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}
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int DebugInformationRecorder::serialize_scope_values(GrowableArray<ScopeValue*>* values) {
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  if (values == nullptr || values->is_empty()) return DebugInformationRecorder::serialized_null;
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  assert(_recording_state == rs_safepoint, "must be recording a safepoint");
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  int result = stream()->position();
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  assert(result != serialized_null, "sanity");
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  stream()->write_int(values->length());
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  for (int index = 0; index < values->length(); index++) {
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    values->at(index)->write_on(stream());
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  }
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  // (See comment below on DebugInformationRecorder::describe_scope.)
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  int shared_result = find_sharable_decode_offset(result);
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  if (shared_result != serialized_null) {
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    stream()->set_position(result);
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    result = shared_result;
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  }
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  return result;
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}
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#ifndef PRODUCT
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// These variables are put into one block to reduce relocations
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// and make it simpler to print from the debugger.
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static
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struct dir_stats_struct {
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  int chunks_queried;
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  int chunks_shared;
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  int chunks_elided;
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  void print() {
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    tty->print_cr("Debug Data Chunks: %d, shared %d, non-SP's elided %d",
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                  chunks_queried, chunks_shared, chunks_elided);
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  }
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} dir_stats;
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#endif //PRODUCT
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int DebugInformationRecorder::find_sharable_decode_offset(int stream_offset) {
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  NOT_PRODUCT(++dir_stats.chunks_queried);
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  int stream_length = stream()->position() - stream_offset;
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  assert(stream_offset != serialized_null, "should not be null");
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  assert(stream_length != 0, "should not be empty");
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  DIR_Chunk* ns = new(this) DIR_Chunk(stream_offset, stream_length, this);
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  DIR_Chunk* match = _all_chunks->insert_sorted<DIR_Chunk::compare>(ns);
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  if (match != ns) {
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    // Found an existing chunk
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    NOT_PRODUCT(++dir_stats.chunks_shared);
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    assert(ns+1 == _next_chunk, "");
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    _next_chunk = ns;
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    return match->offset();
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  } else {
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    // Inserted this chunk, so nothing to do
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    return serialized_null;
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  }
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}
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// must call add_safepoint before: it sets PcDesc and this routine uses
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// the last PcDesc set
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void DebugInformationRecorder::describe_scope(int         pc_offset,
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                                              const methodHandle& methodH,
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                                              ciMethod*   method,
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                                              int         bci,
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                                              bool        reexecute,
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                                              bool        rethrow_exception,
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                                              bool        is_method_handle_invoke,
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                                              bool        return_oop,
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                                              bool        has_ea_local_in_scope,
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                                              bool        arg_escape,
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                                              DebugToken* locals,
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                                              DebugToken* expressions,
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                                              DebugToken* monitors) {
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  assert(_recording_state != rs_null, "nesting of recording calls");
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  PcDesc* last_pd = last_pc();
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  assert(last_pd->pc_offset() == pc_offset, "must be last pc");
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  int sender_stream_offset = last_pd->scope_decode_offset();
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  // update the stream offset of current pc desc
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  int stream_offset = stream()->position();
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  last_pd->set_scope_decode_offset(stream_offset);
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  // Record flags into pcDesc.
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  last_pd->set_should_reexecute(reexecute);
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  last_pd->set_rethrow_exception(rethrow_exception);
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  last_pd->set_is_method_handle_invoke(is_method_handle_invoke);
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  last_pd->set_return_oop(return_oop);
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  last_pd->set_has_ea_local_in_scope(has_ea_local_in_scope);
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  last_pd->set_arg_escape(arg_escape);
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  // serialize sender stream offset
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  stream()->write_int(sender_stream_offset);
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  // serialize scope
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  Metadata* method_enc;
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  if (method != nullptr) {
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    method_enc = method->constant_encoding();
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  } else if (methodH.not_null()) {
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    method_enc = methodH();
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  } else {
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    method_enc = nullptr;
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  }
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  int method_enc_index = oop_recorder()->find_index(method_enc);
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  stream()->write_int(method_enc_index);
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  stream()->write_bci(bci);
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  assert(method == nullptr ||
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         (method->is_native() && bci == 0) ||
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         (!method->is_native() && 0 <= bci && bci < method->code_size()) ||
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         bci == -1, "illegal bci");
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  // serialize the locals/expressions/monitors
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  stream()->write_int((intptr_t) locals);
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  stream()->write_int((intptr_t) expressions);
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  stream()->write_int((intptr_t) monitors);
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  // Here's a tricky bit.  We just wrote some bytes.
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  // Wouldn't it be nice to find that we had already
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  // written those same bytes somewhere else?
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  // If we get lucky this way, reset the stream
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  // and reuse the old bytes.  By the way, this
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  // trick not only shares parent scopes, but also
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  // compresses equivalent non-safepoint PcDescs.
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  int shared_stream_offset = find_sharable_decode_offset(stream_offset);
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  if (shared_stream_offset != serialized_null) {
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    stream()->set_position(stream_offset);
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    last_pd->set_scope_decode_offset(shared_stream_offset);
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  }
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}
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void DebugInformationRecorder::dump_object_pool(GrowableArray<ScopeValue*>* objects) {
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  guarantee( _pcs_length > 0, "safepoint must exist before describing scopes");
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  PcDesc* last_pd = &_pcs[_pcs_length-1];
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  if (objects != nullptr) {
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    for (int i = objects->length() - 1; i >= 0; i--) {
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      objects->at(i)->as_ObjectValue()->set_visited(false);
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    }
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  }
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  int offset = serialize_scope_values(objects);
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  last_pd->set_obj_decode_offset(offset);
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}
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void DebugInformationRecorder::end_scopes(int pc_offset, bool is_safepoint) {
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  assert(_recording_state == (is_safepoint? rs_safepoint: rs_non_safepoint),
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         "nesting of recording calls");
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  debug_only(_recording_state = rs_null);
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  // Try to compress away an equivalent non-safepoint predecessor.
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  // (This only works because we have previously recognized redundant
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  // scope trees and made them use a common scope_decode_offset.)
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  if (_pcs_length >= 2 && recording_non_safepoints()) {
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    PcDesc* last = last_pc();
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    PcDesc* prev = prev_pc();
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    // If prev is (a) not a safepoint and (b) has the same
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    // stream pointer, then it can be coalesced into the last.
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    // This is valid because non-safepoints are only sought
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    // with pc_desc_near, which (when it misses prev) will
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    // search forward until it finds last.
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    // In addition, it does not matter if the last PcDesc
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    // is for a safepoint or not.
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    if (_prev_safepoint_pc < prev->pc_offset() && prev->is_same_info(last)) {
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      assert(prev == last-1, "sane");
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      prev->set_pc_offset(pc_offset);
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      _pcs_length -= 1;
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      NOT_PRODUCT(++dir_stats.chunks_elided);
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    }
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  }
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  // We have just recorded this safepoint.
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  // Remember it in case the previous paragraph needs to know.
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  if (is_safepoint) {
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    _prev_safepoint_pc = pc_offset;
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  }
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}
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#ifdef ASSERT
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bool DebugInformationRecorder::recorders_frozen() {
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  return _oop_recorder->is_complete();
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}
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void DebugInformationRecorder::mark_recorders_frozen() {
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  _oop_recorder->freeze();
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}
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#endif // PRODUCT
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DebugToken* DebugInformationRecorder::create_scope_values(GrowableArray<ScopeValue*>* values) {
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  assert(!recorders_frozen(), "not frozen yet");
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  return (DebugToken*) (intptr_t) serialize_scope_values(values);
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}
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DebugToken* DebugInformationRecorder::create_monitor_values(GrowableArray<MonitorValue*>* monitors) {
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  assert(!recorders_frozen(), "not frozen yet");
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  return (DebugToken*) (intptr_t) serialize_monitor_values(monitors);
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}
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int DebugInformationRecorder::data_size() {
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  debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
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  return _stream->position();
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}
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int DebugInformationRecorder::pcs_size() {
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  debug_only(mark_recorders_frozen());  // mark it "frozen" for asserts
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  if (last_pc()->pc_offset() != PcDesc::upper_offset_limit)
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    add_new_pc_offset(PcDesc::upper_offset_limit);
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  return _pcs_length * sizeof(PcDesc);
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}
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void DebugInformationRecorder::copy_to(nmethod* nm) {
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  nm->copy_scopes_data(stream()->buffer(), stream()->position());
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  nm->copy_scopes_pcs(_pcs, _pcs_length);
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}
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void DebugInformationRecorder::verify(const nmethod* code) {
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  Unimplemented();
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}
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#ifndef PRODUCT
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void DebugInformationRecorder::print_statistics() {
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  dir_stats.print();
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}
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#endif //PRODUCT
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