--- /dev/null	2018-04-03 12:55:20.301839954 +0200
+++ new/src/hotspot/share/gc/z/zMarkStack.cpp	2018-06-08 19:46:17.898620969 +0200
@@ -0,0 +1,392 @@
+/*
+ * Copyright (c) 2016, 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 "gc/z/zErrno.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zLock.inline.hpp"
+#include "gc/z/zMarkStack.inline.hpp"
+#include "logging/log.hpp"
+#include "runtime/atomic.hpp"
+#include "utilities/debug.hpp"
+
+#include <sys/mman.h>
+#include <sys/types.h>
+
+ZMarkStackSpace::ZMarkStackSpace() :
+    _expand_lock(),
+    _top(0),
+    _end(0) {
+  assert(ZMarkStacksMax >= ZMarkStackSpaceExpandSize, "ZMarkStacksMax too small");
+  assert(ZMarkStacksMax <= ZMarkStackSpaceSize, "ZMarkStacksMax too large");
+
+  // Reserve address space
+  const void* res = mmap((void*)ZMarkStackSpaceStart, ZMarkStackSpaceSize,
+                         PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
+  if (res != (void*)ZMarkStackSpaceStart) {
+    log_error(gc, marking)("Failed to reserve address space for marking stacks");
+    return;
+  }
+
+  // Successfully initialized
+  _top = _end = ZMarkStackSpaceStart;
+}
+
+bool ZMarkStackSpace::is_initialized() const {
+  return _top != 0;
+}
+
+bool ZMarkStackSpace::expand() {
+  const size_t max = ZMarkStackSpaceStart + ZMarkStacksMax;
+  if (_end + ZMarkStackSpaceExpandSize > max) {
+    // Expansion limit reached
+    return false;
+  }
+
+  void* const res = mmap((void*)_end, ZMarkStackSpaceExpandSize,
+                         PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0);
+  if (res == MAP_FAILED) {
+    ZErrno err;
+    log_error(gc, marking)("Failed to map memory for marking stacks (%s)", err.to_string());
+    return false;
+  }
+
+  return true;
+}
+
+uintptr_t ZMarkStackSpace::alloc_space(size_t size) {
+  uintptr_t top = _top;
+
+  for (;;) {
+    const uintptr_t new_top = top + size;
+    if (new_top > _end) {
+      // Not enough space left
+      return 0;
+    }
+
+    const uintptr_t prev_top = Atomic::cmpxchg(new_top, &_top, top);
+    if (prev_top == top) {
+      // Success
+      return top;
+    }
+
+    // Retry
+    top = prev_top;
+  }
+}
+
+uintptr_t ZMarkStackSpace::expand_and_alloc_space(size_t size) {
+  ZLocker locker(&_expand_lock);
+
+  // Retry allocation before expanding
+  uintptr_t addr = alloc_space(size);
+  if (addr != 0) {
+    return addr;
+  }
+
+  // Expand stack space
+  if (!expand()) {
+    // We currently can't handle the situation where we
+    // are running out of mark stack space.
+    fatal("Mark stack overflow (allocated " SIZE_FORMAT "M, size " SIZE_FORMAT "M, max " SIZE_FORMAT "M),"
+          " use -XX:ZMarkStacksMax=? to increase this limit",
+          (_end - ZMarkStackSpaceStart) / M, size / M, ZMarkStacksMax / M);
+    return 0;
+  }
+
+  log_debug(gc, marking)("Expanding mark stack space: " SIZE_FORMAT "M->" SIZE_FORMAT "M",
+                         (_end - ZMarkStackSpaceStart) / M,
+                         (_end - ZMarkStackSpaceStart + ZMarkStackSpaceExpandSize) / M);
+
+  // Increment top before end to make sure another
+  // thread can't steal out newly expanded space.
+  addr = Atomic::add(size, &_top) - size;
+  _end += ZMarkStackSpaceExpandSize;
+
+  return addr;
+}
+
+uintptr_t ZMarkStackSpace::alloc(size_t size) {
+  const uintptr_t addr = alloc_space(size);
+  if (addr != 0) {
+    return addr;
+  }
+
+  return expand_and_alloc_space(size);
+}
+
+ZMarkStackAllocator::ZMarkStackAllocator() :
+    _freelist(),
+    _space() {
+  guarantee(sizeof(ZMarkStack) == ZMarkStackSize, "Size mismatch");
+  guarantee(sizeof(ZMarkStackMagazine) <= ZMarkStackSize, "Size mismatch");
+
+  // Prime free list to avoid an immediate space
+  // expansion when marking starts.
+  if (_space.is_initialized()) {
+    prime_freelist();
+  }
+}
+
+bool ZMarkStackAllocator::is_initialized() const {
+  return _space.is_initialized();
+}
+
+void ZMarkStackAllocator::prime_freelist() {
+  for (size_t size = 0; size < ZMarkStackSpaceExpandSize; size += ZMarkStackMagazineSize) {
+    const uintptr_t addr = _space.alloc(ZMarkStackMagazineSize);
+    ZMarkStackMagazine* const magazine = create_magazine_from_space(addr, ZMarkStackMagazineSize);
+    free_magazine(magazine);
+  }
+}
+
+ZMarkStackMagazine* ZMarkStackAllocator::create_magazine_from_space(uintptr_t addr, size_t size) {
+  assert(is_aligned(size, ZMarkStackSize), "Invalid size");
+
+  // Use first stack as magazine
+  ZMarkStackMagazine* const magazine = new ((void*)addr) ZMarkStackMagazine();
+  for (size_t i = ZMarkStackSize; i < size; i += ZMarkStackSize) {
+    ZMarkStack* const stack = new ((void*)(addr + i)) ZMarkStack();
+    const bool success = magazine->push(stack);
+    assert(success, "Magazine should never get full");
+  }
+
+  return magazine;
+}
+
+ZMarkStackMagazine* ZMarkStackAllocator::alloc_magazine() {
+  // Try allocating from the free list first
+  ZMarkStackMagazine* const magazine = _freelist.pop_atomic();
+  if (magazine != NULL) {
+    return magazine;
+  }
+
+  // Allocate new magazine
+  const uintptr_t addr = _space.alloc(ZMarkStackMagazineSize);
+  if (addr == 0) {
+    return NULL;
+  }
+
+  return create_magazine_from_space(addr, ZMarkStackMagazineSize);
+}
+
+void ZMarkStackAllocator::free_magazine(ZMarkStackMagazine* magazine) {
+  _freelist.push_atomic(magazine);
+}
+
+ZMarkStripe::ZMarkStripe() :
+    _published(),
+    _overflowed() {}
+
+ZMarkStripeSet::ZMarkStripeSet() :
+    _nstripes(0),
+    _nstripes_mask(0),
+    _stripes() {}
+
+void ZMarkStripeSet::set_nstripes(size_t nstripes) {
+  assert(is_power_of_2(nstripes), "Must be a power of two");
+  assert(is_power_of_2(ZMarkStripesMax), "Must be a power of two");
+  assert(nstripes >= 1, "Invalid number of stripes");
+  assert(nstripes <= ZMarkStripesMax, "Invalid number of stripes");
+
+  _nstripes = nstripes;
+  _nstripes_mask = nstripes - 1;
+
+  log_debug(gc, marking)("Using " SIZE_FORMAT " mark stripes", _nstripes);
+}
+
+bool ZMarkStripeSet::is_empty() const {
+  for (size_t i = 0; i < _nstripes; i++) {
+    if (!_stripes[i].is_empty()) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+ZMarkStripe* ZMarkStripeSet::stripe_for_worker(uint nworkers, uint worker_id) {
+  const size_t spillover_limit = (nworkers / _nstripes) * _nstripes;
+  size_t index;
+
+  if (worker_id < spillover_limit) {
+    // Not a spillover worker, use natural stripe
+    index = worker_id & _nstripes_mask;
+  } else {
+    // Distribute spillover workers evenly across stripes
+    const size_t spillover_nworkers = nworkers - spillover_limit;
+    const size_t spillover_worker_id = worker_id - spillover_limit;
+    const double spillover_chunk = (double)_nstripes / (double)spillover_nworkers;
+    index = spillover_worker_id * spillover_chunk;
+  }
+
+  assert(index < _nstripes, "Invalid index");
+  return &_stripes[index];
+}
+
+ZMarkThreadLocalStacks::ZMarkThreadLocalStacks() :
+    _magazine(NULL) {
+  for (size_t i = 0; i < ZMarkStripesMax; i++) {
+    _stacks[i] = NULL;
+  }
+}
+
+bool ZMarkThreadLocalStacks::is_empty(const ZMarkStripeSet* stripes) const {
+  for (size_t i = 0; i < stripes->nstripes(); i++) {
+    ZMarkStack* const stack = _stacks[i];
+    if (stack != NULL) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+ZMarkStack* ZMarkThreadLocalStacks::allocate_stack(ZMarkStackAllocator* allocator) {
+  if (_magazine == NULL) {
+    // Allocate new magazine
+    _magazine = allocator->alloc_magazine();
+    if (_magazine == NULL) {
+      return NULL;
+    }
+  }
+
+  ZMarkStack* stack = NULL;
+
+  if (!_magazine->pop(stack)) {
+    // Magazine is empty, convert magazine into a new stack
+    _magazine->~ZMarkStackMagazine();
+    stack = new ((void*)_magazine) ZMarkStack();
+    _magazine = NULL;
+  }
+
+  return stack;
+}
+
+void ZMarkThreadLocalStacks::free_stack(ZMarkStackAllocator* allocator, ZMarkStack* stack) {
+  for (;;) {
+    if (_magazine == NULL) {
+      // Convert stack into a new magazine
+      stack->~ZMarkStack();
+      _magazine = new ((void*)stack) ZMarkStackMagazine();
+      return;
+    }
+
+    if (_magazine->push(stack)) {
+      // Success
+      return;
+    }
+
+    // Free and uninstall full magazine
+    allocator->free_magazine(_magazine);
+    _magazine = NULL;
+  }
+}
+
+bool ZMarkThreadLocalStacks::push_slow(ZMarkStackAllocator* allocator,
+                                       ZMarkStripe* stripe,
+                                       ZMarkStack** stackp,
+                                       ZMarkStackEntry entry,
+                                       bool publish) {
+  ZMarkStack* stack = *stackp;
+
+  for (;;) {
+    if (stack == NULL) {
+      // Allocate and install new stack
+      *stackp = stack = allocate_stack(allocator);
+      if (stack == NULL) {
+        // Out of mark stack memory
+        return false;
+      }
+    }
+
+    if (stack->push(entry)) {
+      // Success
+      return true;
+    }
+
+    // Publish/Overflow and uninstall stack
+    stripe->publish_stack(stack, publish);
+    *stackp = stack = NULL;
+  }
+}
+
+bool ZMarkThreadLocalStacks::pop_slow(ZMarkStackAllocator* allocator,
+                                      ZMarkStripe* stripe,
+                                      ZMarkStack** stackp,
+                                      ZMarkStackEntry& entry) {
+  ZMarkStack* stack = *stackp;
+
+  for (;;) {
+    if (stack == NULL) {
+      // Try steal and install stack
+      *stackp = stack = stripe->steal_stack();
+      if (stack == NULL) {
+        // Nothing to steal
+        return false;
+      }
+    }
+
+    if (stack->pop(entry)) {
+      // Success
+      return true;
+    }
+
+    // Free and uninstall stack
+    free_stack(allocator, stack);
+    *stackp = stack = NULL;
+  }
+}
+
+bool ZMarkThreadLocalStacks::flush(ZMarkStackAllocator* allocator, ZMarkStripeSet* stripes) {
+  bool flushed = false;
+
+  // Flush all stacks
+  for (size_t i = 0; i < stripes->nstripes(); i++) {
+    ZMarkStripe* const stripe = stripes->stripe_at(i);
+    ZMarkStack** const stackp = &_stacks[i];
+    ZMarkStack* const stack = *stackp;
+    if (stack == NULL) {
+      continue;
+    }
+
+    // Free/Publish and uninstall stack
+    if (stack->is_empty()) {
+      free_stack(allocator, stack);
+    } else {
+      stripe->publish_stack(stack);
+      flushed = true;
+    }
+    *stackp = NULL;
+  }
+
+  return flushed;
+}
+
+void ZMarkThreadLocalStacks::free(ZMarkStackAllocator* allocator) {
+  // Free and uninstall magazine
+  if (_magazine != NULL) {
+    allocator->free_magazine(_magazine);
+    _magazine = NULL;
+  }
+}