--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.serviceprovider/src/org/graalvm/compiler/serviceprovider/GraalServices.java	2017-04-28 11:49:04.000000000 +0200
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.serviceprovider/src/org/graalvm/compiler/serviceprovider/GraalServices.java	2017-04-28 11:49:04.000000000 +0200
@@ -22,9 +22,17 @@
  */
 package org.graalvm.compiler.serviceprovider;
 
+import static org.graalvm.compiler.serviceprovider.JDK9Method.Java8OrEarlier;
+import static org.graalvm.compiler.serviceprovider.JDK9Method.addOpens;
+import static org.graalvm.compiler.serviceprovider.JDK9Method.getModule;
+import static org.graalvm.compiler.serviceprovider.JDK9Method.getPackages;
+import static org.graalvm.compiler.serviceprovider.JDK9Method.isOpenTo;
+
+import java.lang.reflect.Method;
 import java.util.Iterator;
 import java.util.ServiceConfigurationError;
 import java.util.ServiceLoader;
+import java.util.Set;
 
 import jdk.vm.ci.services.JVMCIPermission;
 import jdk.vm.ci.services.Services;
@@ -32,14 +40,32 @@
 /**
  * A mechanism for accessing service providers that abstracts over whether Graal is running on
  * JVMCI-8 or JVMCI-9. In JVMCI-8, a JVMCI specific mechanism is used to lookup services via the
- * hidden JVMCI class loader. in JVMCI-9, the standard {@link ServiceLoader} mechanism is used.
+ * hidden JVMCI class loader. In JVMCI-9, the standard {@link ServiceLoader} mechanism is used.
  */
 public final class GraalServices {
 
     private GraalServices() {
     }
 
-    public static final boolean Java8OrEarlier = System.getProperty("java.specification.version").compareTo("1.9") < 0;
+    /**
+     * Opens all JVMCI packages to the module of a given class. This relies on JVMCI already having
+     * opened all its packages to the module defining {@link GraalServices}.
+     *
+     * @param other all JVMCI packages will be opened to the module defining this class
+     */
+    public static void openJVMCITo(Class<?> other) {
+        Object jvmci = getModule.invoke(Services.class);
+        Object otherModule = getModule.invoke(other);
+        if (jvmci != otherModule) {
+            Set<String> packages = getPackages.invoke(jvmci);
+            for (String pkg : packages) {
+                boolean opened = isOpenTo.invoke(jvmci, pkg, otherModule);
+                if (!opened) {
+                    addOpens.invoke(jvmci, pkg, otherModule);
+                }
+            }
+        }
+    }
 
     /**
      * Gets an {@link Iterable} of the providers available for a given service.
@@ -50,9 +76,9 @@
     public static <S> Iterable<S> load(Class<S> service) {
         assert !service.getName().startsWith("jdk.vm.ci") : "JVMCI services must be loaded via " + Services.class.getName();
         if (Java8OrEarlier) {
-            return Services.load(service);
+            return load8(service);
         }
-        ServiceLoader<S> iterable = ServiceLoader.load(service);
+        Iterable<S> iterable = ServiceLoader.load(service);
         return new Iterable<S>() {
             @Override
             public Iterator<S> iterator() {
@@ -66,8 +92,8 @@
                     @Override
                     public S next() {
                         S provider = iterator.next();
-                        // Allow Graal extensions to access JVMCI assuming they have JVMCIPermission
-                        Services.exportJVMCITo(provider.getClass());
+                        // Allow Graal extensions to access JVMCI
+                        openJVMCITo(provider.getClass());
                         return provider;
                     }
 
@@ -81,6 +107,23 @@
     }
 
     /**
+     * {@code Services.load(Class)} is only defined in JVMCI-8.
+     */
+    private static volatile Method loadMethod;
+
+    @SuppressWarnings("unchecked")
+    private static <S> Iterable<S> load8(Class<S> service) throws InternalError {
+        try {
+            if (loadMethod == null) {
+                loadMethod = Services.class.getMethod("load", Class.class);
+            }
+            return (Iterable<S>) loadMethod.invoke(null, service);
+        } catch (Exception e) {
+            throw new InternalError(e);
+        }
+    }
+
+    /**
      * Gets the provider for a given service for which at most one provider must be available.
      *
      * @param service the service whose provider is being requested
@@ -92,16 +135,14 @@
      */
     public static <S> S loadSingle(Class<S> service, boolean required) {
         assert !service.getName().startsWith("jdk.vm.ci") : "JVMCI services must be loaded via " + Services.class.getName();
-        if (Java8OrEarlier) {
-            return Services.loadSingle(service, required);
-        }
-        Iterable<S> providers = ServiceLoader.load(service);
+        Iterable<S> providers = load(service);
         S singleProvider = null;
         try {
             for (Iterator<S> it = providers.iterator(); it.hasNext();) {
                 singleProvider = it.next();
                 if (it.hasNext()) {
-                    throw new InternalError(String.format("Multiple %s providers found", service.getName()));
+                    S other = it.next();
+                    throw new InternalError(String.format("Multiple %s providers found: %s, %s", service.getName(), singleProvider.getClass().getName(), other.getClass().getName()));
                 }
             }
         } catch (ServiceConfigurationError e) {
@@ -111,9 +152,6 @@
             if (required) {
                 throw new InternalError(String.format("No provider for %s found", service.getName()));
             }
-        } else {
-            // Allow Graal extensions to access JVMCI assuming they have JVMCIPermission
-            Services.exportJVMCITo(singleProvider.getClass());
         }
         return singleProvider;
     }