--- /dev/null	2019-10-01 11:37:31.106015611 +0200
+++ new/src/hotspot/os/windows/gc/z/zBackingFile_windows.cpp	2019-10-31 09:39:41.412988740 +0100
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2019, 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/zBackingFile_windows.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zGranuleMap.inline.hpp"
+#include "gc/z/zMapper_windows.hpp"
+#include "logging/log.hpp"
+#include "runtime/globals.hpp"
+#include "utilities/debug.hpp"
+
+// The backing file commits and uncommits physical memory, that can be
+// multi-mapped into the virtual address space. To support fine-graned
+// committing and uncommitting, each ZGranuleSize chunked is mapped to
+// a separate paging file mapping.
+
+ZBackingFile::ZBackingFile() :
+    _handles(MaxHeapSize),
+    _size(0) {}
+
+size_t ZBackingFile::size() const {
+  return _size;
+}
+
+HANDLE ZBackingFile::get_handle(uintptr_t offset) const {
+  HANDLE const handle = _handles.get(offset);
+  assert(handle != 0, "Should be set");
+  return handle;
+}
+
+void ZBackingFile::put_handle(uintptr_t offset, HANDLE handle) {
+  assert(handle != INVALID_HANDLE_VALUE, "Invalid handle");
+  assert(_handles.get(offset) == 0, "Should be cleared");
+  _handles.put(offset, handle);
+}
+
+void ZBackingFile::clear_handle(uintptr_t offset) {
+  assert(_handles.get(offset) != 0, "Should be set");
+  _handles.put(offset, 0);
+}
+
+size_t ZBackingFile::commit_from_paging_file(size_t offset, size_t size) {
+  for (size_t i = 0; i < size; i += ZGranuleSize) {
+    HANDLE const handle = ZMapper::create_and_commit_paging_file_mapping(ZGranuleSize);
+    if (handle == 0) {
+      return i;
+    }
+
+    put_handle(offset + i, handle);
+  }
+
+  return size;
+}
+
+size_t ZBackingFile::uncommit_from_paging_file(size_t offset, size_t size) {
+  for (size_t i = 0; i < size; i += ZGranuleSize) {
+    HANDLE const handle = get_handle(offset + i);
+    clear_handle(offset + i);
+    ZMapper::close_paging_file_mapping(handle);
+  }
+
+  return size;
+}
+
+size_t ZBackingFile::commit(size_t offset, size_t length) {
+  log_trace(gc, heap)("Committing memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
+                      offset / M, (offset + length) / M, length / M);
+
+  const size_t committed = commit_from_paging_file(offset, length);
+
+  const size_t end = offset + committed;
+  if (end > _size) {
+    // Update size
+    _size = end;
+  }
+
+  return committed;
+}
+
+size_t ZBackingFile::uncommit(size_t offset, size_t length) {
+  log_trace(gc, heap)("Uncommitting memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
+                      offset / M, (offset + length) / M, length / M);
+
+  return uncommit_from_paging_file(offset, length);
+}
+
+void ZBackingFile::map(uintptr_t addr, size_t size, size_t offset) const {
+  assert(is_aligned(offset, ZGranuleSize), "Misaligned");
+  assert(is_aligned(addr, ZGranuleSize), "Misaligned");
+  assert(is_aligned(size, ZGranuleSize), "Misaligned");
+
+  for (size_t i = 0; i < size; i += ZGranuleSize) {
+    HANDLE const handle = get_handle(offset + i);
+    ZMapper::map_view_replace_placeholder(handle, 0 /* offset */, addr + i, ZGranuleSize);
+  }
+}
+
+void ZBackingFile::unmap(uintptr_t addr, size_t size) const {
+  assert(is_aligned(addr, ZGranuleSize), "Misaligned");
+  assert(is_aligned(size, ZGranuleSize), "Misaligned");
+
+  for (size_t i = 0; i < size; i += ZGranuleSize) {
+    ZMapper::unmap_view_preserve_placeholder(addr + i, ZGranuleSize);
+  }
+}