diff -r 000000000000 -r 959103a6100f src/share/classes/com/sun/tools/sjavac/Log.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/classes/com/sun/tools/sjavac/Log.java	Wed Apr 27 01:34:52 2016 +0800
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2012, 2013, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 com.sun.tools.sjavac;
+
+import java.io.PrintStream;
+
+/**
+ * Utility class only for sjavac logging.
+ * The log level can be set using for example --log=DEBUG on the sjavac command line.
+ *
+ * <p><b>This is NOT part of any supported API.
+ * If you write code that depends on this, you do so at your own
+ * risk.  This code and its internal interfaces are subject to change
+ * or deletion without notice.</b></p>
+ */
+public class Log {
+    private static PrintStream out, err;
+
+    public final static int WARN = 1;
+    public final static int INFO = 2;
+    public final static int DEBUG = 3;
+    public final static int TRACE = 4;
+    private static int level = WARN;
+
+    static public void trace(String msg) {
+        if (level >= TRACE) {
+            out.println(msg);
+        }
+    }
+
+    static public void debug(String msg) {
+        if (level >= DEBUG) {
+            out.println(msg);
+        }
+    }
+
+    static public void info(String msg) {
+        if (level >= INFO) {
+            out.println(msg);
+        }
+    }
+
+    static public void warn(String msg) {
+        err.println(msg);
+    }
+
+    static public void error(String msg) {
+        err.println(msg);
+    }
+
+    static public void setLogLevel(String l, PrintStream o, PrintStream e)
+        throws ProblemException {
+        out = o;
+        err = e;
+        if (l.equals("warn")) level = WARN;
+        else if (l.equals("info")) level = INFO;
+        else if (l.equals("debug")) level = DEBUG;
+        else if (l.equals("trace")) level = TRACE;
+        else throw new ProblemException("No such log level \""+l+"\"");
+    }
+
+    static public boolean isTracing() {
+        return level >= TRACE;
+    }
+
+    static public boolean isDebugging() {
+        return level >= DEBUG;
+    }
+}