1 /*
   2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  *   - Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  *
  11  *   - Redistributions in binary form must reproduce the above copyright
  12  *     notice, this list of conditions and the following disclaimer in the
  13  *     documentation and/or other materials provided with the distribution.
  14  *
  15  *   - Neither the name of Oracle nor the names of its
  16  *     contributors may be used to endorse or promote products derived
  17  *     from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  20  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  27  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31 
  32 // Simple sample to demonstrate openjdk asmtools assembler with
  33 // nashorn dynalink linker in a invokedynamic instruction.
  34 //
  35 // To assemble this file, use the following command:
  36 //
  37 //    java -cp <asmtools.jar> org.openjdk.asmtools.Main jasm Main.asm
  38 //
  39 // See also: https://wiki.openjdk.java.net/display/CodeTools/asmtools
  40 //
  41 // NOTE: Uses dynalink API defined by JEP-276 (http://openjdk.java.net/jeps/276)
  42 
  43 super public class Main
  44         version 52:0
  45 {
  46 
  47 private static final Field linker:"Ljdk/dynalink/DynamicLinker;";
  48 
  49 /*
  50    static {
  51         // create dynalink linker factory
  52         final DynamicLinkerFactory factory = new DynamicLinkerFactory();
  53 
  54         // create standard linker that can handle Java POJOs
  55         linker = factory.createLinker();
  56    }
  57 */
  58 static Method "<clinit>":"()V"
  59         stack 2 locals 1
  60 {
  61     new     class jdk/dynalink/DynamicLinkerFactory;
  62     dup;
  63     invokespecial   Method jdk/dynalink/DynamicLinkerFactory."<init>":"()V";
  64     astore_0;
  65     aload_0;
  66     invokevirtual   Method jdk/dynalink/DynamicLinkerFactory.createLinker:"()Ljdk/dynalink/DynamicLinker;";
  67     putstatic       Field linker:"Ljdk/dynalink/DynamicLinker;";
  68     return;
  69 }
  70 
  71 /*
  72     // Bootstrap method used with invokedynamic methods
  73 
  74     public static CallSite bootstrap(MethodHandles.Lookup caller, String name, MethodType type) {
  75         // use dynalink linker to perform the actual linking
  76         return linker.link(
  77             new SimpleRelinkableCallSite(
  78                 new CallSiteDescriptor(
  79                     MethodHandles.publicLookup(), 
  80                     new NamedOperation(StandardOperation.GET_PROPERTY, name), type)
  81             )
  82         );
  83     }
  84 
  85  */
  86 public static Method bootstrap:"(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;"
  87         stack 10 locals 3
  88 {
  89     getstatic       Field linker:"Ljdk/dynalink/DynamicLinker;";
  90     new     class jdk/dynalink/support/SimpleRelinkableCallSite;
  91     dup;
  92     new     class jdk/dynalink/CallSiteDescriptor;
  93     dup;
  94     invokestatic    Method java/lang/invoke/MethodHandles.publicLookup:"()Ljava/lang/invoke/MethodHandles$Lookup;";
  95     new     class jdk/dynalink/NamedOperation;
  96     dup;
  97     getstatic       Field jdk/dynalink/StandardOperation.GET_PROPERTY:"Ljdk/dynalink/StandardOperation;";
  98     aload_1;
  99     invokespecial   Method jdk/dynalink/NamedOperation."<init>":"(Ljdk/dynalink/Operation;Ljava/lang/Object;)V";
 100     aload_2;
 101     invokespecial   Method jdk/dynalink/CallSiteDescriptor."<init>":"(Ljava/lang/invoke/MethodHandles$Lookup;Ljdk/dynalink/Operation;Ljava/lang/invoke/MethodType;)V";
 102     invokespecial   Method jdk/dynalink/support/SimpleRelinkableCallSite."<init>":"(Ljdk/dynalink/CallSiteDescriptor;)V";
 103     invokevirtual   Method jdk/dynalink/DynamicLinker.link:"(Ljdk/dynalink/RelinkableCallSite;)Ljdk/dynalink/RelinkableCallSite;";
 104     checkcast       class java/lang/invoke/CallSite;
 105     areturn;
 106 }
 107 
 108 // default constructor that does nothing!
 109 public Method "<init>":"()V"
 110         stack 1 locals 1
 111 {
 112     aload_0;
 113     invokespecial       Method java/lang/Object."<init>":"()V";
 114     return;
 115 }
 116 
 117 public static Method main:"([Ljava/lang/String;)V"
 118         stack 2 locals 2
 119 {
 120     // List l = new ArrayList();
 121     new class java/util/ArrayList;
 122     dup;
 123     invokespecial       Method java/util/ArrayList."<init>":"()V";
 124     astore_1;
 125     aload_1;
 126 
 127     // l.add("hello");
 128     ldc String "hello";
 129     invokeinterface     InterfaceMethod java/util/List.add:"(Ljava/lang/Object;)Z",  2;
 130     pop;
 131 
 132     // l.add("world");
 133     aload_1;
 134     ldc String "world";
 135     invokeinterface     InterfaceMethod java/util/List.add:"(Ljava/lang/Object;)Z",  2;
 136     pop;
 137 
 138     // printLength(l);
 139     aload_1;
 140     invokestatic        Method printLength:"(Ljava/lang/Object;)V";
 141 
 142     // printLength(args); // args is argument of main method
 143     aload_0;
 144     invokestatic        Method printLength:"(Ljava/lang/Object;)V";
 145     return;
 146 }
 147 
 148 private static Method printLength:"(Ljava/lang/Object;)V"
 149         stack 2 locals 1
 150 {
 151     getstatic   Field java/lang/System.out:"Ljava/io/PrintStream;";
 152     aload_0;
 153 
 154     // Using bootstrap method in this class with the following invokedynamic
 155     // which uses dynalink linker. Dynalink's bean linker handles Java beans.
 156     // 'length' property on a bean - arrays, lists supported
 157 
 158     invokedynamic   InvokeDynamic REF_invokeStatic:Main.bootstrap:"(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;":"length":"(Ljava/lang/Object;)Ljava/lang/Object;";
 159 
 160     // print 'length' value
 161     invokevirtual       Method java/io/PrintStream.println:"(Ljava/lang/Object;)V";
 162     return;
 163 }
 164 
 165 } // end Class Main