--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zNMethodTable.cpp	2018-06-06 00:42:05.916221923 +0200
@@ -0,0 +1,465 @@
+/*
+ * Copyright (c) 2017, 2018, 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/relocInfo.hpp"
+#include "code/nativeInst.hpp"
+#include "code/nmethod.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zHash.inline.hpp"
+#include "gc/z/zNMethodTable.hpp"
+#include "logging/log.hpp"
+#include "memory/allocation.inline.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/atomic.hpp"
+#include "utilities/debug.hpp"
+
+class ZNMethodWithImmediateOops {
+private:
+  nmethod* const _nm;
+  const size_t   _nimmediate_oops;
+
+  static size_t header_size();
+
+  ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops);
+
+public:
+  static ZNMethodWithImmediateOops* create(nmethod* nm, const GrowableArray<oop*>& immediate_oops);
+  static void destroy(ZNMethodWithImmediateOops* nmi);
+
+  nmethod* method() const;
+  size_t immediate_oops_count() const;
+  oop** immediate_oops_begin() const;
+  oop** immediate_oops_begin_safe() const;
+  oop** immediate_oops_end() const;
+};
+
+size_t ZNMethodWithImmediateOops::header_size() {
+  const size_t size = sizeof(ZNMethodWithImmediateOops);
+  assert(is_aligned(size, sizeof(oop*)), "Header misaligned");
+  return size;
+}
+
+ZNMethodWithImmediateOops::ZNMethodWithImmediateOops(nmethod* nm, const GrowableArray<oop*>& immediate_oops) :
+    _nm(nm),
+    _nimmediate_oops(immediate_oops.length()) {
+  // Save all immediate oops
+  for (size_t i = 0; i < _nimmediate_oops; i++) {
+    immediate_oops_begin()[i] = immediate_oops.at(i);
+  }
+}
+
+ZNMethodWithImmediateOops* ZNMethodWithImmediateOops::create(nmethod* nm, const GrowableArray<oop*>& immediate_oops) {
+  // Allocate memory for the ZNMethodWithImmediateOops object
+  // plus the immediate oop* array that follows right after.
+  const size_t size = header_size() + (sizeof(oop*) * immediate_oops.length());
+  void* const method_with_immediate_oops = NEW_C_HEAP_ARRAY(uint8_t, size, mtGC);
+  return ::new (method_with_immediate_oops) ZNMethodWithImmediateOops(nm, immediate_oops);
+}
+
+void ZNMethodWithImmediateOops::destroy(ZNMethodWithImmediateOops* nmi) {
+  FREE_C_HEAP_ARRAY(uint8_t, nmi);
+}
+
+nmethod* ZNMethodWithImmediateOops::method() const {
+  return _nm;
+}
+
+size_t ZNMethodWithImmediateOops::immediate_oops_count() const {
+  return _nimmediate_oops;
+}
+
+oop** ZNMethodWithImmediateOops::immediate_oops_begin() const {
+  // The immediate oop* array starts immediately after this object
+  return (oop**)((uintptr_t)this + header_size());
+}
+
+oop** ZNMethodWithImmediateOops::immediate_oops_begin_safe() const {
+  // Non-entrant nmethods have a jump instruction patched into the beginning
+  // of the verified entry point, which could have overwritten an immediate
+  // oop. If so, make sure we skip over that oop.
+  if (_nm->is_not_entrant()) {
+    oop* const first_immediate_oop = *immediate_oops_begin();
+    oop* const safe_begin = (oop*)(_nm->verified_entry_point() + NativeJump::instruction_size);
+    if (first_immediate_oop < safe_begin) {
+      // First immediate oop overwritten, skip it
+      return immediate_oops_begin() + 1;
+    }
+  }
+
+  // First immediate oop not overwritten
+  return immediate_oops_begin();
+}
+
+
+oop** ZNMethodWithImmediateOops::immediate_oops_end() const {
+  return immediate_oops_begin() + immediate_oops_count();
+}
+
+ZNMethodTableEntry* ZNMethodTable::_table = NULL;
+size_t ZNMethodTable::_size = 0;
+size_t ZNMethodTable::_nregistered = 0;
+size_t ZNMethodTable::_nunregistered = 0;
+volatile size_t ZNMethodTable::_claimed = 0;
+
+ZNMethodTableEntry ZNMethodTable::create_entry(nmethod* nm) {
+  GrowableArray<oop*> immediate_oops;
+  bool non_immediate_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
+      non_immediate_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.
+      immediate_oops.push(r->oop_addr());
+    }
+  }
+
+  // oops_count() returns the number of oops in the oop table plus one
+  if (immediate_oops.is_empty() && nm->oops_count() == 1) {
+    // No oops found, return empty entry
+    return ZNMethodTableEntry();
+  }
+
+  if (immediate_oops.is_empty()) {
+    // No immediate oops found, return entry without immediate oops
+    return ZNMethodTableEntry(nm, non_immediate_oops);
+  }
+
+  // Return entry with immediate oops
+  return ZNMethodTableEntry(ZNMethodWithImmediateOops::create(nm, immediate_oops), non_immediate_oops);
+}
+
+void ZNMethodTable::destroy_entry(ZNMethodTableEntry entry) {
+  if (entry.immediate_oops()) {
+    ZNMethodWithImmediateOops::destroy(entry.method_with_immediate_oops());
+  }
+}
+
+nmethod* ZNMethodTable::method(ZNMethodTableEntry entry) {
+  return entry.immediate_oops() ? entry.method_with_immediate_oops()->method() : entry.method();
+}
+
+size_t ZNMethodTable::first_index(const nmethod* nm, size_t size) {
+  assert(is_power_of_2(size), "Invalid size");
+  const size_t mask = size - 1;
+  const size_t hash = ZHash::address_to_uint32((uintptr_t)nm);
+  return hash & mask;
+}
+
+size_t ZNMethodTable::next_index(size_t prev_index, size_t size) {
+  assert(is_power_of_2(size), "Invalid size");
+  const size_t mask = size - 1;
+  return (prev_index + 1) & mask;
+}
+
+bool ZNMethodTable::register_entry(ZNMethodTableEntry* table, size_t size, ZNMethodTableEntry entry) {
+  const nmethod* const nm = method(entry);
+  size_t index = first_index(nm, size);
+
+  for (;;) {
+    const ZNMethodTableEntry table_entry = table[index];
+
+    if (!table_entry.registered() && !table_entry.unregistered()) {
+      // Insert new entry
+      table[index] = entry;
+      return true;
+    }
+
+    if (table_entry.registered() && method(table_entry) == nm) {
+      // Replace existing entry
+      destroy_entry(table_entry);
+      table[index] = entry;
+      return false;
+    }
+
+    index = next_index(index, size);
+  }
+}
+
+bool ZNMethodTable::unregister_entry(ZNMethodTableEntry* table, size_t size, const nmethod* nm) {
+  if (size == 0) {
+    // Table is empty
+    return false;
+  }
+
+  size_t index = first_index(nm, size);
+
+  for (;;) {
+    const ZNMethodTableEntry table_entry = table[index];
+
+    if (!table_entry.registered() && !table_entry.unregistered()) {
+      // Entry not found
+      return false;
+    }
+
+    if (table_entry.registered() && method(table_entry) == nm) {
+      // Remove entry
+      destroy_entry(table_entry);
+      table[index] = ZNMethodTableEntry(true /* unregistered */);
+      return true;
+    }
+
+    index = next_index(index, size);
+  }
+}
+
+void ZNMethodTable::rebuild(size_t new_size) {
+  assert(is_power_of_2(new_size), "Invalid size");
+
+  log_debug(gc, nmethod)("Rebuilding NMethod Table: "
+                         SIZE_FORMAT "->" SIZE_FORMAT " entries, "
+                         SIZE_FORMAT "(%.0lf%%->%.0lf%%) registered, "
+                         SIZE_FORMAT "(%.0lf%%->%.0lf%%) unregistered",
+                         _size, new_size,
+                         _nregistered, percent_of(_nregistered, _size), percent_of(_nregistered, new_size),
+                         _nunregistered, percent_of(_nunregistered, _size), 0.0);
+
+  // Allocate new table
+  ZNMethodTableEntry* const new_table = new ZNMethodTableEntry[new_size];
+
+  // Transfer all registered entries
+  for (size_t i = 0; i < _size; i++) {
+    const ZNMethodTableEntry entry = _table[i];
+    if (entry.registered()) {
+      register_entry(new_table, new_size, entry);
+    }
+  }
+
+  // Delete old table
+  delete [] _table;
+
+  // Install new table
+  _table = new_table;
+  _size = new_size;
+  _nunregistered = 0;
+}
+
+void ZNMethodTable::rebuild_if_needed() {
+  // The hash table uses linear probing. To avoid wasting memory while
+  // at the same time maintaining good hash collision behavior we want
+  // to keep the table occupancy between 30% and 70%. The table always
+  // grows/shrinks by doubling/halving its size. Pruning of unregistered
+  // entries is done by rebuilding the table with or without resizing it.
+  const size_t min_size = 1024;
+  const size_t shrink_threshold = _size * 0.30;
+  const size_t prune_threshold = _size * 0.65;
+  const size_t grow_threshold = _size * 0.70;
+
+  if (_size == 0) {
+    // Initialize table
+    rebuild(min_size);
+  } else if (_nregistered < shrink_threshold && _size > min_size) {
+    // Shrink table
+    rebuild(_size / 2);
+  } else if (_nregistered + _nunregistered > grow_threshold) {
+    // Prune or grow table
+    if (_nregistered < prune_threshold) {
+      // Prune table
+      rebuild(_size);
+    } else {
+      // Grow table
+      rebuild(_size * 2);
+    }
+  }
+}
+
+void ZNMethodTable::log_register(const nmethod* nm, ZNMethodTableEntry entry) {
+  LogTarget(Trace, gc, nmethod) log;
+  if (!log.is_enabled()) {
+    return;
+  }
+
+  log.print("Register NMethod: %s.%s (" PTR_FORMAT "), "
+            "Compiler: %s, Oops: %d, ImmediateOops: " SIZE_FORMAT ", NonImmediateOops: %s",
+            nm->method()->method_holder()->external_name(),
+            nm->method()->name()->as_C_string(),
+            p2i(nm),
+            nm->compiler_name(),
+            nm->oops_count() - 1,
+            entry.immediate_oops() ? entry.method_with_immediate_oops()->immediate_oops_count() : 0,
+            BOOL_TO_STR(entry.non_immediate_oops()));
+
+  LogTarget(Trace, gc, nmethod, oops) log_oops;
+  if (!log_oops.is_enabled()) {
+    return;
+  }
+
+  // Print nmethod oops table
+  oop* const begin = nm->oops_begin();
+  oop* const end = nm->oops_end();
+  for (oop* p = begin; p < end; p++) {
+    log_oops.print("           Oop[" SIZE_FORMAT "] " PTR_FORMAT " (%s)",
+                   (p - begin), p2i(*p), (*p)->klass()->external_name());
+  }
+
+  if (entry.immediate_oops()) {
+    // Print nmethod immediate oops
+    const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();
+    oop** const begin = nmi->immediate_oops_begin();
+    oop** const end = nmi->immediate_oops_end();
+    for (oop** p = begin; p < end; p++) {
+      log_oops.print("  ImmediateOop[" SIZE_FORMAT "] " PTR_FORMAT " @ " PTR_FORMAT " (%s)",
+                     (p - begin), p2i(**p), p2i(*p), (**p)->klass()->external_name());
+    }
+  }
+}
+
+void ZNMethodTable::log_unregister(const nmethod* nm) {
+  LogTarget(Debug, gc, nmethod) log;
+  if (!log.is_enabled()) {
+    return;
+  }
+
+  log.print("Unregister NMethod: %s.%s (" PTR_FORMAT ")",
+            nm->method()->method_holder()->external_name(),
+            nm->method()->name()->as_C_string(),
+            p2i(nm));
+}
+
+size_t ZNMethodTable::registered_nmethods() {
+  return _nregistered;
+}
+
+size_t ZNMethodTable::unregistered_nmethods() {
+  return _nunregistered;
+}
+
+void ZNMethodTable::register_nmethod(nmethod* nm) {
+  ResourceMark rm;
+
+  // Create entry
+  const ZNMethodTableEntry entry = create_entry(nm);
+
+  log_register(nm, entry);
+
+  if (!entry.registered()) {
+    // Method doesn't have any oops, ignore it
+    return;
+  }
+
+  // Grow/Shrink/Prune table if needed
+  rebuild_if_needed();
+
+  // Insert new entry
+  if (register_entry(_table, _size, entry)) {
+    // New entry registered. When register_entry() instead returns
+    // false the nmethod was already in the table so we do not want
+    // to increase number of registered entries in that case.
+    _nregistered++;
+  }
+}
+
+void ZNMethodTable::unregister_nmethod(nmethod* nm) {
+  ResourceMark rm;
+
+  log_unregister(nm);
+
+  // Remove entry
+  if (unregister_entry(_table, _size, nm)) {
+    // Entry was unregistered. When unregister_entry() instead returns
+    // false the nmethod was not in the table (because it didn't have
+    // any oops) so we do not want to decrease the number of registered
+    // entries in that case.
+    _nregistered--;
+    _nunregistered++;
+  }
+}
+
+void ZNMethodTable::gc_prologue() {
+  _claimed = 0;
+}
+
+void ZNMethodTable::gc_epilogue() {
+  assert(_claimed >= _size, "Failed to claim all table entries");
+}
+
+void ZNMethodTable::entry_oops_do(ZNMethodTableEntry entry, OopClosure* cl) {
+  nmethod* const nm = method(entry);
+  if (!nm->is_alive()) {
+    // No need to visit oops
+    return;
+  }
+
+  // Process oops table
+  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()) {
+      cl->do_oop(p);
+    }
+  }
+
+  if (entry.immediate_oops()) {
+    // Process immediate oops
+    const ZNMethodWithImmediateOops* const nmi = entry.method_with_immediate_oops();
+    oop** const begin = nmi->immediate_oops_begin_safe();
+    oop** const end = nmi->immediate_oops_end();
+    for (oop** p = begin; p < end; p++) {
+      cl->do_oop(*p);
+    }
+  }
+
+  if (entry.non_immediate_oops()) {
+    // Process non-immediate oops
+    nm->fix_oop_relocations();
+  }
+}
+
+void ZNMethodTable::oops_do(OopClosure* cl) {
+  for (;;) {
+    // Claim table partition. Each partition is currently sized to span
+    // two cache lines. This number is just a guess, but seems to work well.
+    const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);
+    const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _size);
+    const size_t partition_end = MIN2(partition_start + partition_size, _size);
+    if (partition_start == partition_end) {
+      // End of table
+      break;
+    }
+
+    // Process table partition
+    for (size_t i = partition_start; i < partition_end; i++) {
+      const ZNMethodTableEntry entry = _table[i];
+      if (entry.registered()) {
+        entry_oops_do(entry, cl);
+      }
+    }
+  }
+}