--- a/graal/com.oracle.graal.java/src/com/oracle/graal/java/GraphBuilderPhase.java	Wed Mar 18 02:15:37 2015 +0100
+++ b/graal/com.oracle.graal.java/src/com/oracle/graal/java/GraphBuilderPhase.java	Wed Mar 18 11:46:06 2015 +0100
@@ -25,6 +25,7 @@
 import static com.oracle.graal.api.meta.DeoptimizationAction.*;
 import static com.oracle.graal.api.meta.DeoptimizationReason.*;
 import static com.oracle.graal.bytecode.Bytecodes.*;
+import static com.oracle.graal.compiler.common.GraalInternalError.*;
 import static com.oracle.graal.compiler.common.GraalOptions.*;
 import static com.oracle.graal.graph.iterators.NodePredicates.*;
 import static com.oracle.graal.java.AbstractBytecodeParser.Options.*;
@@ -1149,22 +1150,63 @@
                 }
             }
 
+            /**
+             * Contains all the assertion checking logic around the application of an
+             * {@link InvocationPlugin}. This class is only loaded when assertions are enabled.
+             */
+            class InvocationPluginAssertions {
+                final InvocationPlugin plugin;
+                final ValueNode[] args;
+                final ResolvedJavaMethod targetMethod;
+                final Kind resultType;
+                final int beforeStackSize;
+                final boolean needsNullCheck;
+                final int nodeCount;
+                final Mark mark;
+
+                public InvocationPluginAssertions(InvocationPlugin plugin, ValueNode[] args, ResolvedJavaMethod targetMethod, Kind resultType) {
+                    guarantee(assertionsEnabled(), "%s should only be loaded and instantiated if assertions are enabled", getClass().getSimpleName());
+                    this.plugin = plugin;
+                    this.targetMethod = targetMethod;
+                    this.args = args;
+                    this.resultType = resultType;
+                    this.beforeStackSize = frameState.stackSize;
+                    this.needsNullCheck = !targetMethod.isStatic() && args[0].getKind() == Kind.Object && !StampTool.isPointerNonNull(args[0].stamp());
+                    this.nodeCount = currentGraph.getNodeCount();
+                    this.mark = currentGraph.getMark();
+                }
+
+                boolean check(boolean pluginResult) {
+                    if (pluginResult == true) {
+                        assert beforeStackSize + resultType.getSlotCount() == frameState.stackSize : "plugin manipulated the stack incorrectly " + targetMethod;
+                        NodeIterable<Node> newNodes = currentGraph.getNewNodes(mark);
+                        assert !needsNullCheck || args[0].usages().filter(isNotA(FrameState.class)).isEmpty() || containsNullCheckOf(newNodes, args[0]) : format(
+                                        "plugin needs to null check the receiver of %s: receiver=%s%n\tplugin at %s", targetMethod.format("%H.%n(%p)"), args[0],
+                                        plugin.getApplySourceLocation(metaAccess));
+                        for (Node n : newNodes) {
+                            if (n instanceof StateSplit) {
+                                StateSplit stateSplit = (StateSplit) n;
+                                assert stateSplit.stateAfter() != null : format("%s node added by plugin for %s need to have a non-null frame state: %s%n\tplugin at %s",
+                                                StateSplit.class.getSimpleName(), targetMethod.format("%H.%n(%p)"), stateSplit, plugin.getApplySourceLocation(metaAccess));
+                            }
+                        }
+                    } else {
+                        assert nodeCount == currentGraph.getNodeCount() : "plugin that returns false must not create new nodes";
+                        assert beforeStackSize == frameState.stackSize : "plugin that returns false must modify the stack";
+                    }
+                    return true;
+                }
+            }
+
             private boolean tryInvocationPlugin(ValueNode[] args, ResolvedJavaMethod targetMethod, Kind resultType) {
                 InvocationPlugin plugin = graphBuilderConfig.getPlugins().getInvocationPlugins().lookupInvocation(targetMethod);
                 if (plugin != null) {
-                    int beforeStackSize = frameState.stackSize;
-                    boolean needsNullCheck = !targetMethod.isStatic() && args[0].getKind() == Kind.Object && !StampTool.isPointerNonNull(args[0].stamp());
-                    int nodeCount = currentGraph.getNodeCount();
-                    Mark mark = needsNullCheck ? currentGraph.getMark() : null;
+                    InvocationPluginAssertions assertions = assertionsEnabled() ? new InvocationPluginAssertions(plugin, args, targetMethod, resultType) : null;
                     if (InvocationPlugin.execute(this, targetMethod, plugin, args)) {
-                        assert beforeStackSize + resultType.getSlotCount() == frameState.stackSize : "plugin manipulated the stack incorrectly " + targetMethod;
-                        assert !needsNullCheck || args[0].usages().filter(isNotA(FrameState.class)).isEmpty() || containsNullCheckOf(currentGraph.getNewNodes(mark), args[0]) : format(
-                                        "plugin needs to null check the receiver of %s: receiver=%s%n\tplugin at %s", targetMethod.format("%H.%n(%p)"), args[0],
-                                        plugin.getApplySourceLocation(metaAccess));
+                        assert assertions.check(true);
                         return true;
                     }
-                    assert nodeCount == currentGraph.getNodeCount() : "plugin that returns false must not create new nodes";
-                    assert beforeStackSize == frameState.stackSize : "plugin that returns false must modify the stack";
+                    assert assertions.check(false);
                 }
                 return false;
             }
@@ -2392,4 +2434,11 @@
     static String nSpaces(int n) {
         return n == 0 ? "" : format("%" + n + "s", "");
     }
+
+    @SuppressWarnings("all")
+    private static boolean assertionsEnabled() {
+        boolean assertionsEnabled = false;
+        assert assertionsEnabled = true;
+        return assertionsEnabled;
+    }
 }