/*
* 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()) ||
(method->is_compiled_lambda_form() && bci == -99) || // this might happen in C1
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