--- /dev/null	2017-01-22 10:16:57.869617664 -0800
+++ new/src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.common/src/jdk/vm/ci/common/JVMCIError.java	2017-02-15 16:55:38.858855189 -0800
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2011, 2014, 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 jdk.vm.ci.common;
+
+import java.util.ArrayList;
+import java.util.Locale;
+
+/**
+ * Indicates a condition in JVMCI related code that should never occur during normal operation.
+ */
+public class JVMCIError extends Error {
+
+    private static final long serialVersionUID = 531632331813456233L;
+
+    public static RuntimeException unimplemented() {
+        throw new JVMCIError("unimplemented");
+    }
+
+    public static RuntimeException unimplemented(String msg) {
+        throw new JVMCIError("unimplemented: %s", msg);
+    }
+
+    public static RuntimeException shouldNotReachHere() {
+        throw new JVMCIError("should not reach here");
+    }
+
+    public static RuntimeException shouldNotReachHere(String msg) {
+        throw new JVMCIError("should not reach here: %s", msg);
+    }
+
+    public static RuntimeException shouldNotReachHere(Throwable cause) {
+        throw new JVMCIError(cause);
+    }
+
+    /**
+     * Checks a given condition and throws a {@link JVMCIError} if it is false. Guarantees are
+     * stronger than assertions in that they are always checked. Error messages for guarantee
+     * violations should clearly indicate the nature of the problem as well as a suggested solution
+     * if possible.
+     *
+     * @param condition the condition to check
+     * @param msg the message that will be associated with the error, in
+     *            {@link String#format(String, Object...)} syntax
+     * @param args arguments to the format string
+     */
+    public static void guarantee(boolean condition, String msg, Object... args) {
+        if (!condition) {
+            throw new JVMCIError("failed guarantee: " + msg, args);
+        }
+    }
+
+    /**
+     * This constructor creates a {@link JVMCIError} with a given message.
+     *
+     * @param msg the message that will be associated with the error
+     */
+    public JVMCIError(String msg) {
+        super(msg);
+    }
+
+    /**
+     * This constructor creates a {@link JVMCIError} with a message assembled via
+     * {@link String#format(String, Object...)}. It always uses the ENGLISH locale in order to
+     * always generate the same output.
+     *
+     * @param msg the message that will be associated with the error, in String.format syntax
+     * @param args parameters to String.format - parameters that implement {@link Iterable} will be
+     *            expanded into a [x, x, ...] representation.
+     */
+    public JVMCIError(String msg, Object... args) {
+        super(format(msg, args));
+    }
+
+    /**
+     * This constructor creates a {@link JVMCIError} for a given causing Throwable instance.
+     *
+     * @param cause the original exception that contains additional information on this error
+     */
+    public JVMCIError(Throwable cause) {
+        super(cause);
+    }
+
+    private static String format(String msg, Object... args) {
+        if (args != null) {
+            // expand Iterable parameters into a list representation
+            for (int i = 0; i < args.length; i++) {
+                if (args[i] instanceof Iterable<?>) {
+                    ArrayList<Object> list = new ArrayList<>();
+                    for (Object o : (Iterable<?>) args[i]) {
+                        list.add(o);
+                    }
+                    args[i] = list.toString();
+                }
+            }
+        }
+        return String.format(Locale.ENGLISH, msg, args);
+    }
+}