--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/gcArguments.cpp	Tue Nov 07 11:58:52 2017 +0100
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
+ * 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/shared/gcArguments.hpp"
+#include "gc/serial/serialArguments.hpp"
+#include "runtime/globals.hpp"
+#include "runtime/globals_extension.hpp"
+#include "runtime/java.hpp"
+#include "runtime/os.hpp"
+#include "utilities/macros.hpp"
+
+#if INCLUDE_ALL_GCS
+#include "gc/parallel/parallelArguments.hpp"
+#include "gc/cms/cmsArguments.hpp"
+#include "gc/g1/g1Arguments.hpp"
+#endif
+
+GCArguments* GCArguments::_instance = NULL;
+
+GCArguments* GCArguments::arguments() {
+  assert(is_initialized(), "Heap factory not yet created");
+  return _instance;
+}
+
+bool GCArguments::is_initialized() {
+  return _instance != NULL;
+}
+
+bool GCArguments::gc_selected() {
+#if INCLUDE_ALL_GCS
+  return UseSerialGC || UseParallelGC || UseParallelOldGC || UseConcMarkSweepGC || UseG1GC;
+#else
+  return UseSerialGC;
+#endif // INCLUDE_ALL_GCS
+}
+
+void GCArguments::select_gc() {
+  if (!gc_selected()) {
+    select_gc_ergonomically();
+    if (!gc_selected()) {
+      vm_exit_during_initialization("Garbage collector not selected (default collector explicitly disabled)", NULL);
+    }
+  }
+}
+
+void GCArguments::select_gc_ergonomically() {
+#if INCLUDE_ALL_GCS
+  if (os::is_server_class_machine()) {
+    FLAG_SET_ERGO_IF_DEFAULT(bool, UseG1GC, true);
+  } else {
+    FLAG_SET_ERGO_IF_DEFAULT(bool, UseSerialGC, true);
+  }
+#else
+  UNSUPPORTED_OPTION(UseG1GC);
+  UNSUPPORTED_OPTION(UseParallelGC);
+  UNSUPPORTED_OPTION(UseParallelOldGC);
+  UNSUPPORTED_OPTION(UseConcMarkSweepGC);
+  FLAG_SET_ERGO_IF_DEFAULT(bool, UseSerialGC, true);
+#endif // INCLUDE_ALL_GCS
+}
+
+void GCArguments::initialize_flags() {
+#if INCLUDE_ALL_GCS
+  if (AssumeMP && !UseSerialGC) {
+    if (FLAG_IS_DEFAULT(ParallelGCThreads) && ParallelGCThreads == 1) {
+      warning("If the number of processors is expected to increase from one, then"
+              " you should configure the number of parallel GC threads appropriately"
+              " using -XX:ParallelGCThreads=N");
+    }
+  }
+  if (MinHeapFreeRatio == 100) {
+    // Keeping the heap 100% free is hard ;-) so limit it to 99%.
+    FLAG_SET_ERGO(uintx, MinHeapFreeRatio, 99);
+  }
+
+  // If class unloading is disabled, also disable concurrent class unloading.
+  if (!ClassUnloading) {
+    FLAG_SET_CMDLINE(bool, CMSClassUnloadingEnabled, false);
+    FLAG_SET_CMDLINE(bool, ClassUnloadingWithConcurrentMark, false);
+  }
+#endif // INCLUDE_ALL_GCS
+}
+
+jint GCArguments::initialize() {
+  assert(!is_initialized(), "GC arguments already initialized");
+
+  select_gc();
+
+#if !INCLUDE_ALL_GCS
+  if (UseParallelGC || UseParallelOldGC) {
+    jio_fprintf(defaultStream::error_stream(), "UseParallelGC not supported in this VM.\n");
+    return JNI_ERR;
+  } else if (UseG1GC) {
+    jio_fprintf(defaultStream::error_stream(), "UseG1GC not supported in this VM.\n");
+    return JNI_ERR;
+  } else if (UseConcMarkSweepGC) {
+    jio_fprintf(defaultStream::error_stream(), "UseConcMarkSweepGC not supported in this VM.\n");
+    return JNI_ERR;
+#else
+  if (UseParallelGC || UseParallelOldGC) {
+    _instance = new ParallelArguments();
+  } else if (UseG1GC) {
+    _instance = new G1Arguments();
+  } else if (UseConcMarkSweepGC) {
+    _instance = new CMSArguments();
+#endif
+  } else if (UseSerialGC) {
+    _instance = new SerialArguments();
+  } else {
+    ShouldNotReachHere();
+  }
+  return JNI_OK;
+}