--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.amd64/src/org/graalvm/compiler/replacements/amd64/AMD64GraphBuilderPlugins.java	2019-03-16 05:58:01.837426070 +0100
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.amd64/src/org/graalvm/compiler/replacements/amd64/AMD64GraphBuilderPlugins.java	2019-03-16 05:58:01.465423441 +0100
@@ -32,7 +32,6 @@
 import static org.graalvm.compiler.replacements.nodes.UnaryMathIntrinsicNode.UnaryOperation.LOG10;
 import static org.graalvm.compiler.replacements.nodes.UnaryMathIntrinsicNode.UnaryOperation.SIN;
 import static org.graalvm.compiler.replacements.nodes.UnaryMathIntrinsicNode.UnaryOperation.TAN;
-import static org.graalvm.compiler.serviceprovider.JavaVersionUtil.JAVA_SPECIFICATION_VERSION;
 import static org.graalvm.compiler.serviceprovider.JavaVersionUtil.Java11OrEarlier;
 import static org.graalvm.compiler.serviceprovider.JavaVersionUtil.Java8OrEarlier;
 
@@ -71,7 +70,7 @@
 
 public class AMD64GraphBuilderPlugins {
 
-    public static void register(Plugins plugins, BytecodeProvider replacementsBytecodeProvider, AMD64 arch, boolean explicitUnsafeNullChecks) {
+    public static void register(Plugins plugins, BytecodeProvider replacementsBytecodeProvider, AMD64 arch, boolean explicitUnsafeNullChecks, boolean emitJDK9StringSubstitutions) {
         InvocationPlugins invocationPlugins = plugins.getInvocationPlugins();
         invocationPlugins.defer(new Runnable() {
             @Override
@@ -83,8 +82,10 @@
                                 new JavaKind[]{JavaKind.Int, JavaKind.Long, JavaKind.Object, JavaKind.Boolean, JavaKind.Byte, JavaKind.Short, JavaKind.Char, JavaKind.Float, JavaKind.Double});
                 registerUnsafePlugins(invocationPlugins, replacementsBytecodeProvider, explicitUnsafeNullChecks);
                 registerStringPlugins(invocationPlugins, replacementsBytecodeProvider);
-                registerStringLatin1Plugins(invocationPlugins, replacementsBytecodeProvider);
-                registerStringUTF16Plugins(invocationPlugins, replacementsBytecodeProvider);
+                if (emitJDK9StringSubstitutions) {
+                    registerStringLatin1Plugins(invocationPlugins, replacementsBytecodeProvider);
+                    registerStringUTF16Plugins(invocationPlugins, replacementsBytecodeProvider);
+                }
                 registerMathPlugins(invocationPlugins, arch, replacementsBytecodeProvider);
                 registerArraysEqualsPlugins(invocationPlugins, replacementsBytecodeProvider);
             }
@@ -215,30 +216,26 @@
     }
 
     private static void registerStringLatin1Plugins(InvocationPlugins plugins, BytecodeProvider replacementsBytecodeProvider) {
-        if (JAVA_SPECIFICATION_VERSION >= 9) {
-            Registration r = new Registration(plugins, "java.lang.StringLatin1", replacementsBytecodeProvider);
-            r.setAllowOverwrite(true);
-            r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "compareTo", byte[].class, byte[].class);
-            r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "compareToUTF16", byte[].class, byte[].class);
-            r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "inflate", byte[].class, int.class, char[].class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "inflate", byte[].class, int.class, byte[].class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "indexOf", byte[].class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "indexOf", byte[].class, int.class, byte[].class, int.class, int.class);
-        }
+        Registration r = new Registration(plugins, "java.lang.StringLatin1", replacementsBytecodeProvider);
+        r.setAllowOverwrite(true);
+        r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "compareTo", byte[].class, byte[].class);
+        r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "compareToUTF16", byte[].class, byte[].class);
+        r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "inflate", byte[].class, int.class, char[].class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "inflate", byte[].class, int.class, byte[].class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "indexOf", byte[].class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringLatin1Substitutions.class, "indexOf", byte[].class, int.class, byte[].class, int.class, int.class);
     }
 
     private static void registerStringUTF16Plugins(InvocationPlugins plugins, BytecodeProvider replacementsBytecodeProvider) {
-        if (JAVA_SPECIFICATION_VERSION >= 9) {
-            Registration r = new Registration(plugins, "java.lang.StringUTF16", replacementsBytecodeProvider);
-            r.setAllowOverwrite(true);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compareTo", byte[].class, byte[].class);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compareToLatin1", byte[].class, byte[].class);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compress", char[].class, int.class, byte[].class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compress", byte[].class, int.class, byte[].class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "indexOfCharUnsafe", byte[].class, int.class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "indexOfUnsafe", byte[].class, int.class, byte[].class, int.class, int.class);
-            r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "indexOfLatin1Unsafe", byte[].class, int.class, byte[].class, int.class, int.class);
-        }
+        Registration r = new Registration(plugins, "java.lang.StringUTF16", replacementsBytecodeProvider);
+        r.setAllowOverwrite(true);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compareTo", byte[].class, byte[].class);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compareToLatin1", byte[].class, byte[].class);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compress", char[].class, int.class, byte[].class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "compress", byte[].class, int.class, byte[].class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "indexOfCharUnsafe", byte[].class, int.class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "indexOfUnsafe", byte[].class, int.class, byte[].class, int.class, int.class);
+        r.registerMethodSubstitution(AMD64StringUTF16Substitutions.class, "indexOfLatin1Unsafe", byte[].class, int.class, byte[].class, int.class, int.class);
     }
 
     private static void registerUnsafePlugins(InvocationPlugins plugins, BytecodeProvider replacementsBytecodeProvider, boolean explicitUnsafeNullChecks) {