--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shenandoah/shenandoahNMethod.cpp	Wed Nov 27 11:52:57 2019 -0500
@@ -0,0 +1,516 @@
+/*
+ * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
+ *
+ * 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 "gc/shenandoah/shenandoahClosures.inline.hpp"
+#include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
+#include "gc/shenandoah/shenandoahHeap.inline.hpp"
+#include "gc/shenandoah/shenandoahNMethod.inline.hpp"
+#include "memory/resourceArea.hpp"
+
+ShenandoahNMethod::ShenandoahNMethod(nmethod* nm, GrowableArray<oop*>& oops, bool non_immediate_oops) :
+  _nm(nm), _oops(NULL), _oops_count(0), _unregistered(false) {
+
+  if (!oops.is_empty()) {
+    _oops_count = oops.length();
+    _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);
+    for (int c = 0; c < _oops_count; c++) {
+      _oops[c] = oops.at(c);
+    }
+  }
+  _has_non_immed_oops = non_immediate_oops;
+
+  assert_same_oops();
+}
+
+ShenandoahNMethod::~ShenandoahNMethod() {
+  if (_oops != NULL) {
+    FREE_C_HEAP_ARRAY(oop*, _oops);
+  }
+}
+
+class ShenandoahHasCSetOopClosure : public OopClosure {
+private:
+  ShenandoahHeap* const _heap;
+  bool                  _has_cset_oops;
+
+public:
+  ShenandoahHasCSetOopClosure() :
+    _heap(ShenandoahHeap::heap()),
+    _has_cset_oops(false) {
+  }
+
+  bool has_cset_oops() const {
+    return _has_cset_oops;
+  }
+
+  void do_oop(oop* p) {
+    oop value = RawAccess<>::oop_load(p);
+    if (!_has_cset_oops && _heap->in_collection_set(value)) {
+      _has_cset_oops = true;
+    }
+  }
+
+  void do_oop(narrowOop* p) {
+    ShouldNotReachHere();
+  }
+};
+
+bool ShenandoahNMethod::has_cset_oops(ShenandoahHeap *heap) {
+  ShenandoahHasCSetOopClosure cl;
+  oops_do(&cl);
+  return cl.has_cset_oops();
+}
+
+void ShenandoahNMethod::update() {
+  ResourceMark rm;
+  bool non_immediate_oops = false;
+  GrowableArray<oop*> oops;
+
+  detect_reloc_oops(nm(), oops, non_immediate_oops);
+  if (oops.length() != _oops_count) {
+    if (_oops != NULL) {
+      FREE_C_HEAP_ARRAY(oop*, _oops);
+      _oops = NULL;
+    }
+
+    _oops_count = oops.length();
+    if (_oops_count > 0) {
+      _oops = NEW_C_HEAP_ARRAY(oop*, _oops_count, mtGC);
+    }
+  }
+
+  for (int index = 0; index < _oops_count; index ++) {
+    _oops[index] = oops.at(index);
+  }
+  _has_non_immed_oops = non_immediate_oops;
+
+  assert_same_oops();
+}
+
+void ShenandoahNMethod::oops_do(OopClosure* oops, bool fix_relocations) {
+  for (int c = 0; c < _oops_count; c ++) {
+    oops->do_oop(_oops[c]);
+  }
+
+  oop* const begin = _nm->oops_begin();
+  oop* const end = _nm->oops_end();
+  for (oop* p = begin; p < end; p++) {
+    if (*p != Universe::non_oop_word()) {
+      oops->do_oop(p);
+    }
+  }
+
+  if (fix_relocations && _has_non_immed_oops) {
+    _nm->fix_oop_relocations();
+  }
+}
+
+void ShenandoahNMethod::detect_reloc_oops(nmethod* nm, GrowableArray<oop*>& oops, bool& has_non_immed_oops) {
+  has_non_immed_oops = false;
+  // Find all oops relocations
+  RelocIterator iter(nm);
+  while (iter.next()) {
+    if (iter.type() != relocInfo::oop_type) {
+      // Not an oop
+      continue;
+    }
+
+    oop_Relocation* r = iter.oop_reloc();
+    if (!r->oop_is_immediate()) {
+      // Non-immediate oop found
+      has_non_immed_oops = true;
+      continue;
+    }
+
+    if (r->oop_value() != NULL) {
+      // Non-NULL immediate oop found. NULL oops can safely be
+      // ignored since the method will be re-registered if they
+      // are later patched to be non-NULL.
+      oops.push(r->oop_addr());
+    }
+  }
+}
+
+ShenandoahNMethod* ShenandoahNMethod::for_nmethod(nmethod* nm) {
+  ResourceMark rm;
+  bool non_immediate_oops = false;
+  GrowableArray<oop*> oops;
+
+  detect_reloc_oops(nm, oops, non_immediate_oops);
+
+  // No embedded oops
+  if(!ShenandoahConcurrentRoots::can_do_concurrent_class_unloading() &&
+    oops.is_empty() && nm->oops_begin() >= nm->oops_end()) {
+    return NULL;
+  }
+
+  return new ShenandoahNMethod(nm, oops, non_immediate_oops);
+}
+
+void ShenandoahNMethod::heal_nmethod(nmethod* nm) {
+  ShenandoahNMethod* data = gc_data(nm);
+  assert(data != NULL, "Sanity");
+  assert(data->lock()->owned_by_self(), "Must hold the lock");
+
+  ShenandoahEvacuateUpdateRootsClosure cl;
+  data->oops_do(&cl, true /*fix relocation*/);
+}
+
+#ifdef ASSERT
+void ShenandoahNMethod::assert_alive_and_correct() {
+  assert(_nm->is_alive(), "only alive nmethods here");
+  ShenandoahHeap* heap = ShenandoahHeap::heap();
+  for (int c = 0; c < _oops_count; c++) {
+    oop *loc = _oops[c];
+    assert(_nm->code_contains((address) loc) || _nm->oops_contains(loc), "nmethod should contain the oop*");
+    oop o = RawAccess<>::oop_load(loc);
+    shenandoah_assert_correct_except(loc, o, o == NULL || heap->is_full_gc_move_in_progress());
+  }
+
+  oop* const begin = _nm->oops_begin();
+  oop* const end = _nm->oops_end();
+  for (oop* p = begin; p < end; p++) {
+    if (*p != Universe::non_oop_word()) {
+      oop o = RawAccess<>::oop_load(p);
+      shenandoah_assert_correct_except(p, o, o == NULL || heap->is_full_gc_move_in_progress());
+    }
+  }
+}
+
+class ShenandoahNMethodOopDetector : public OopClosure {
+private:
+  ResourceMark rm; // For growable array allocation below.
+  GrowableArray<oop*> _oops;
+
+public:
+  ShenandoahNMethodOopDetector() : _oops(10) {};
+
+  void do_oop(oop* o) {
+    _oops.append(o);
+  }
+  void do_oop(narrowOop* o) {
+    fatal("NMethods should not have compressed oops embedded.");
+  }
+
+  GrowableArray<oop*>* oops() {
+    return &_oops;
+  }
+
+  bool has_oops() {
+    return !_oops.is_empty();
+  }
+};
+
+void ShenandoahNMethod::assert_same_oops(bool allow_dead) {
+  ShenandoahNMethodOopDetector detector;
+  nm()->oops_do(&detector, allow_dead);
+
+  GrowableArray<oop*>* oops = detector.oops();
+
+  assert(oops->length() == oop_count(), "Must match");
+
+  for (int index = 0; index < _oops_count; index ++) {
+    assert(oops->contains(_oops[index]), "Must contain this oop");
+  }
+
+  for (oop* p = nm()->oops_begin(); p < nm()->oops_end(); p ++) {
+    assert(oops->contains(p), "Must contain this oop");
+  }
+}
+
+void ShenandoahNMethod::assert_no_oops(nmethod* nm, bool allow_dead) {
+  ShenandoahNMethodOopDetector detector;
+  nm->oops_do(&detector, allow_dead);
+  assert(detector.oops()->length() == 0, "Should not have oops");
+}
+#endif
+
+ShenandoahNMethodTable::ShenandoahNMethodTable() :
+  _heap(ShenandoahHeap::heap()),
+  _size(minSize),
+  _index(0),
+  _iteration_in_progress(false) {
+  _array = NEW_C_HEAP_ARRAY(ShenandoahNMethod*, _size, mtGC);
+}
+
+ShenandoahNMethodTable::~ShenandoahNMethodTable() {
+  assert(_array != NULL, "Sanity");
+  FREE_C_HEAP_ARRAY(ShenandoahNMethod*, _array);
+}
+
+void ShenandoahNMethodTable::register_nmethod(nmethod* nm) {
+  assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
+  assert(_index >= 0 && _index <= _size, "Sanity");
+
+  ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
+  ShenandoahReentrantLocker data_locker(data != NULL ? data->lock() : NULL);
+
+  if (data != NULL) {
+    assert(contain(nm), "Must have been registered");
+    data->update();
+  } else {
+    data = ShenandoahNMethod::for_nmethod(nm);
+    if (data == NULL) {
+      assert(!ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),
+             "Only possible when concurrent class unloading is off");
+      return;
+    }
+    ShenandoahNMethod::attach_gc_data(nm, data);
+    ShenandoahLocker locker(&_lock);
+    log_register_nmethod(nm);
+    append(data);
+  }
+  // Disarm new nmethod
+  ShenandoahNMethod::disarm_nmethod(nm);
+}
+
+void ShenandoahNMethodTable::unregister_nmethod(nmethod* nm) {
+  assert_locked_or_safepoint(CodeCache_lock);
+
+  ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
+  if (data == NULL) {
+    assert(!ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),
+           "Only possible when concurrent class unloading is off");
+    ShenandoahNMethod::assert_no_oops(nm, true /*allow_dead*/);
+    return;
+  }
+
+  if (Thread::current()->is_Code_cache_sweeper_thread()) {
+    wait_until_concurrent_iteration_done();
+  }
+  log_unregister_nmethod(nm);
+  ShenandoahLocker locker(&_lock);
+  assert(contain(nm), "Must have been registered");
+
+  ShenandoahReentrantLocker data_locker(data->lock());
+  data->mark_unregistered();
+}
+
+void ShenandoahNMethodTable::flush_nmethod(nmethod* nm) {
+  assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
+  assert(Thread::current()->is_Code_cache_sweeper_thread(), "Must from Sweep thread");
+  ShenandoahNMethod* data = ShenandoahNMethod::gc_data(nm);
+  assert(data != NULL || !ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),
+         "Only possible when concurrent class unloading is off");
+  if (data == NULL) {
+    ShenandoahNMethod::assert_no_oops(nm, true /*allow_dead*/);
+    return;
+  }
+
+  // Can not alter the array when iteration is in progress
+  wait_until_concurrent_iteration_done();
+  log_flush_nmethod(nm);
+
+  ShenandoahLocker locker(&_lock);
+  int idx = index_of(nm);
+  assert(idx >= 0 && idx < _index, "Invalid index");
+  ShenandoahNMethod::attach_gc_data(nm, NULL);
+  remove(idx);
+}
+
+bool ShenandoahNMethodTable::contain(nmethod* nm) const {
+  return index_of(nm) != -1;
+}
+
+ShenandoahNMethod* ShenandoahNMethodTable::at(int index) const {
+  assert(index >= 0 && index < _index, "Out of bound");
+  return _array[index];
+}
+
+int ShenandoahNMethodTable::index_of(nmethod* nm) const {
+  for (int index = 0; index < length(); index ++) {
+    if (_array[index]->nm() == nm) {
+      return index;
+    }
+  }
+  return -1;
+}
+
+void ShenandoahNMethodTable::remove(int idx) {
+  shenandoah_assert_locked_or_safepoint(CodeCache_lock);
+  assert(!_iteration_in_progress, "Can not happen");
+  assert(_index >= 0 && _index <= _size, "Sanity");
+
+  assert(idx >= 0 && idx < _index, "Out of bound");
+  ShenandoahNMethod* snm = _array[idx];
+
+  _index --;
+  _array[idx] = _array[_index];
+
+  delete snm;
+}
+
+void ShenandoahNMethodTable::wait_until_concurrent_iteration_done() {
+  assert(CodeCache_lock->owned_by_self(), "Lock must be held");
+  while (iteration_in_progress()) {
+    CodeCache_lock->wait_without_safepoint_check();
+  }
+}
+
+void ShenandoahNMethodTable::append(ShenandoahNMethod* snm) {
+  if (is_full()) {
+    int new_size = 2 * _size;
+    ShenandoahNMethod** old_table = _array;
+
+    // Rebuild table and replace current one
+    rebuild(new_size);
+
+    // An iteration is in progress over early snapshot,
+    // can not release the array until iteration is completed
+    if (!iteration_in_progress()) {
+      FREE_C_HEAP_ARRAY(ShenandoahNMethod*, old_table);
+    }
+  }
+
+  _array[_index ++] = snm;
+  assert(_index >= 0 && _index <= _size, "Sanity");
+}
+
+void ShenandoahNMethodTable::rebuild(int size) {
+  ShenandoahNMethod** arr = NEW_C_HEAP_ARRAY(ShenandoahNMethod*, size, mtGC);
+  for (int index = 0; index < _index; index ++) {
+      arr[index] = _array[index];
+  }
+  _array = arr;
+  _size = size;
+}
+
+ShenandoahNMethodTableSnapshot* ShenandoahNMethodTable::snapshot_for_iteration() {
+  assert(!iteration_in_progress(), "Already in progress");
+  _iteration_in_progress = true;
+
+  return new ShenandoahNMethodTableSnapshot(this);
+}
+
+void ShenandoahNMethodTable::finish_iteration(ShenandoahNMethodTableSnapshot* snapshot) {
+  assert(iteration_in_progress(), "Why we here?");
+  assert(snapshot != NULL, "No snapshot");
+  _iteration_in_progress = false;
+
+  // Table has been rebuilt during iteration, free old table
+  if (snapshot->_array != _array) {
+    FREE_C_HEAP_ARRAY(ShenandoahNMethod*, snapshot->_array);
+  }
+  delete snapshot;
+}
+
+void ShenandoahNMethodTable::log_register_nmethod(nmethod* nm) {
+  LogTarget(Debug, gc, nmethod) log;
+  if (!log.is_enabled()) {
+    return;
+  }
+
+  ResourceMark rm;
+  log.print("Register NMethod: %s.%s [" PTR_FORMAT "] (%s)",
+            nm->method()->method_holder()->external_name(),
+            nm->method()->name()->as_C_string(),
+            p2i(nm),
+            nm->compiler_name());
+}
+
+void ShenandoahNMethodTable::log_unregister_nmethod(nmethod* nm) {
+  LogTarget(Debug, gc, nmethod) log;
+  if (!log.is_enabled()) {
+    return;
+  }
+
+  ResourceMark rm;
+  log.print("Unregister NMethod: %s.%s [" PTR_FORMAT "]",
+            nm->method()->method_holder()->external_name(),
+            nm->method()->name()->as_C_string(),
+            p2i(nm));
+}
+
+void ShenandoahNMethodTable::log_flush_nmethod(nmethod* nm) {
+  LogTarget(Debug, gc, nmethod) log;
+  if (!log.is_enabled()) {
+    return;
+  }
+
+  ResourceMark rm;
+  log.print("Flush NMethod: (" PTR_FORMAT ")", p2i(nm));
+}
+
+#ifdef ASSERT
+void ShenandoahNMethodTable::assert_nmethods_alive_and_correct() {
+  assert_locked_or_safepoint(CodeCache_lock);
+
+  for (int index = 0; index < length(); index ++) {
+    ShenandoahNMethod* m = _array[index];
+    // Concurrent unloading may have dead nmethods to be cleaned by sweeper
+    if (m->is_unregistered()) continue;
+    m->assert_alive_and_correct();
+  }
+}
+#endif
+
+ShenandoahNMethodTableSnapshot::ShenandoahNMethodTableSnapshot(ShenandoahNMethodTable* table) :
+  _heap(ShenandoahHeap::heap()), _table(table), _array(table->_array), _length(table->_index), _claimed(0) {
+}
+
+void ShenandoahNMethodTableSnapshot::concurrent_nmethods_do(NMethodClosure* cl) {
+  size_t stride = 256; // educated guess
+
+  ShenandoahNMethod** list = _array;
+  size_t max = (size_t)_length;
+  while (_claimed < max) {
+    size_t cur = Atomic::add(&_claimed, stride) - stride;
+    size_t start = cur;
+    size_t end = MIN2(cur + stride, max);
+    if (start >= max) break;
+
+    for (size_t idx = start; idx < end; idx++) {
+      ShenandoahNMethod* data = list[idx];
+      assert(data != NULL, "Should not be NULL");
+      if (!data->is_unregistered()) {
+        cl->do_nmethod(data->nm());
+      }
+    }
+  }
+}
+
+ShenandoahConcurrentNMethodIterator::ShenandoahConcurrentNMethodIterator(ShenandoahNMethodTable* table) :
+  _table(table), _table_snapshot(NULL) {
+}
+
+void ShenandoahConcurrentNMethodIterator::nmethods_do_begin() {
+  assert(CodeCache_lock->owned_by_self(), "Lock must be held");
+  assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),
+         "Only for concurrent class unloading");
+  _table_snapshot = _table->snapshot_for_iteration();
+}
+
+void ShenandoahConcurrentNMethodIterator::nmethods_do(NMethodClosure* cl) {
+  assert(_table_snapshot != NULL, "Must first call nmethod_do_begin()");
+  _table_snapshot->concurrent_nmethods_do(cl);
+}
+
+void ShenandoahConcurrentNMethodIterator::nmethods_do_end() {
+  assert(CodeCache_lock->owned_by_self(), "Lock must be held");
+  assert(ShenandoahConcurrentRoots::can_do_concurrent_class_unloading(),
+         "Only for concurrent class unloading");
+  _table->finish_iteration(_table_snapshot);
+  CodeCache_lock->notify_all();
+}