1 /*
   2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package jdk.tools.jlink.internal.plugins.optim;
  26 
  27 import java.io.IOException;
  28 import java.util.Map.Entry;
  29 import java.util.Set;
  30 import java.util.function.Consumer;
  31 import jdk.internal.org.objectweb.asm.ClassReader;
  32 import jdk.tools.jlink.internal.plugins.asm.AsmPools;
  33 import jdk.internal.org.objectweb.asm.tree.ClassNode;
  34 import jdk.internal.org.objectweb.asm.tree.MethodNode;
  35 import jdk.tools.jlink.internal.plugins.OptimizationPlugin.MethodOptimizer;
  36 import jdk.tools.jlink.internal.plugins.asm.AsmModulePool;
  37 import jdk.tools.jlink.internal.plugins.optim.ControlFlow.Block;
  38 import jdk.tools.jlink.internal.plugins.optim.ReflectionOptimizer.Data;
  39 import jdk.tools.jlink.internal.plugins.optim.ReflectionOptimizer.TypeResolver;
  40 
  41 
  42 /**
  43  * MethodOptimizer that removes Class.forName when possible.
  44  * WARNING: This code is experimental.
  45  * TODO: Need to check that the type is accessible prior to replace with a constant.
  46  */
  47 public class ForNameFolding implements MethodOptimizer {
  48 
  49     private int numNotReplaced;
  50     private int numReplacement;
  51     private int numRemovedHandlers;
  52     private int instructionsRemoved;
  53 
  54     private Consumer<String> logger;
  55 
  56     @Override
  57     public boolean optimize(Consumer<String> logger, AsmPools pools,
  58             AsmModulePool modulePool,
  59             ClassNode cn, MethodNode m, TypeResolver resolver) throws Exception {
  60         this.logger = logger;
  61         Data data = ReflectionOptimizer.replaceWithClassConstant(cn, m, createResolver(resolver));
  62         instructionsRemoved += data.removedInstructions();
  63         numRemovedHandlers += data.removedHandlers().size();
  64         for (Entry<String, Set<Block>> entry : data.removedHandlers().entrySet()) {
  65             logRemoval(cn.name + "." + m.name + "removed block for " + entry.getKey()
  66                     + " : " + entry.getValue());
  67         }
  68         return data.removedInstructions() > 0;
  69     }
  70 
  71     public TypeResolver createResolver(TypeResolver resolver) {
  72         return (ClassNode cn, MethodNode mn, String type) -> {
  73             ClassReader reader = resolver.resolve(cn, mn, type);
  74             if (reader == null) {
  75                 logNotReplaced(type);
  76             } else {
  77                 logReplaced(type);
  78             }
  79             return reader;
  80         };
  81     }
  82 
  83     private void logReplaced(String type) {
  84         numReplacement += 1;
  85     }
  86 
  87     private void logNotReplaced(String type) {
  88         numNotReplaced += 1;
  89         if (logger != null) {
  90             logger.accept(type + " not resolved");
  91         }
  92     }
  93 
  94     private void logRemoval(String content) {
  95         numRemovedHandlers += 1;
  96         if (logger != null) {
  97             logger.accept(content);
  98         }
  99     }
 100 
 101     @Override
 102     public void close() throws IOException {
 103         if (logger != null) {
 104             logger.accept("Class.forName Folding results:\n " + numReplacement
 105                     + " removed reflection. " + numRemovedHandlers
 106                     + " removed exception handlers."
 107                     + numNotReplaced + " types unknown. "
 108                     + instructionsRemoved + " instructions removed\n");
 109         }
 110     }
 111 }