--- /dev/null	2017-11-16 08:17:56.803999947 +0100
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/replacements/StringUTF16Substitutions.java	2019-03-09 03:58:00.913476252 +0100
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 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.
+ */
+
+
+package org.graalvm.compiler.hotspot.replacements;
+
+import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfigBase.INJECTED_VMCONFIG;
+import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.SLOW_PATH_PROBABILITY;
+import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.probability;
+
+import jdk.vm.ci.meta.DeoptimizationAction;
+import jdk.vm.ci.meta.DeoptimizationReason;
+import jdk.vm.ci.meta.JavaKind;
+import org.graalvm.compiler.api.replacements.ClassSubstitution;
+import org.graalvm.compiler.api.replacements.MethodSubstitution;
+import org.graalvm.compiler.nodes.DeoptimizeNode;
+import org.graalvm.compiler.nodes.java.NewArrayNode;
+import org.graalvm.compiler.replacements.arraycopy.ArrayCopyCallNode;
+
+// JaCoCo Exclude
+
+/**
+ * Substitutions for {@code StringUTF16} methods for JDK9 and later.
+ */
+@ClassSubstitution(className = "java.lang.StringUTF16", optional = true)
+public class StringUTF16Substitutions {
+
+    private static final int MAX_LENGTH = Integer.MAX_VALUE >> 1;
+
+    @MethodSubstitution
+    public static byte[] toBytes(char[] value, int srcBegin, int length) {
+        if (probability(SLOW_PATH_PROBABILITY, srcBegin < 0) ||
+                        probability(SLOW_PATH_PROBABILITY, length < 0) ||
+                        probability(SLOW_PATH_PROBABILITY, length > MAX_LENGTH) ||
+                        probability(SLOW_PATH_PROBABILITY, srcBegin > value.length - length)) {
+            DeoptimizeNode.deopt(DeoptimizationAction.None, DeoptimizationReason.BoundsCheckException);
+        }
+        byte[] val = (byte[]) NewArrayNode.newUninitializedArray(Byte.TYPE, length << 1);
+        // the intrinsic does not perform bounds/type checks, so it can be used here.
+        // Using KillsAny variant since we are reading and writing 2 different types.
+        ArrayCopyCallNode.disjointArraycopyKillsAny(value, srcBegin, val, 0, length, JavaKind.Char, HotSpotReplacementsUtil.getHeapWordSize(INJECTED_VMCONFIG));
+        return val;
+    }
+
+    @MethodSubstitution
+    public static void getChars(byte[] value, int srcBegin, int srcEnd, char[] dst, int dstBegin) {
+        int length = srcEnd - srcBegin;
+        if (probability(SLOW_PATH_PROBABILITY, srcBegin < 0) ||
+                        probability(SLOW_PATH_PROBABILITY, length < 0) ||
+                        probability(SLOW_PATH_PROBABILITY, srcBegin > (value.length >> 1) - length) ||
+                        probability(SLOW_PATH_PROBABILITY, dstBegin > dst.length - length)) {
+            DeoptimizeNode.deopt(DeoptimizationAction.None, DeoptimizationReason.BoundsCheckException);
+        }
+        // The intrinsic does not perform bounds/type checks, so it can be used here.
+        // Using KillsAny variant since we are reading and writing 2 different types.
+        ArrayCopyCallNode.disjointArraycopyKillsAny(value, srcBegin, dst, dstBegin, length, JavaKind.Char, HotSpotReplacementsUtil.getHeapWordSize(INJECTED_VMCONFIG));
+    }
+}