1 /*
   2  * Copyright (c) 2013, 2014, 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.graalvm.compiler.replacements.nodes;
  24 
  25 import org.graalvm.compiler.core.common.type.StampPair;
  26 import org.graalvm.compiler.graph.Node;
  27 import org.graalvm.compiler.graph.NodeClass;
  28 import org.graalvm.compiler.graph.spi.Canonicalizable;
  29 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
  30 import org.graalvm.compiler.nodeinfo.NodeInfo;
  31 import org.graalvm.compiler.nodes.CallTargetNode.InvokeKind;
  32 import org.graalvm.compiler.nodes.ConstantNode;
  33 import org.graalvm.compiler.nodes.ValueNode;
  34 
  35 import jdk.vm.ci.meta.JavaConstant;
  36 import jdk.vm.ci.meta.MetaAccessProvider;
  37 import jdk.vm.ci.meta.ResolvedJavaMethod;
  38 
  39 /**
  40  * This node class can be used to create {@link MacroNode}s for simple pure functions like
  41  * {@link System#identityHashCode(Object)}.
  42  */
  43 @NodeInfo
  44 public abstract class PureFunctionMacroNode extends MacroStateSplitNode implements Canonicalizable {
  45 
  46     public static final NodeClass<PureFunctionMacroNode> TYPE = NodeClass.create(PureFunctionMacroNode.class);
  47 
  48     public PureFunctionMacroNode(NodeClass<? extends MacroNode> c, InvokeKind invokeKind, ResolvedJavaMethod targetMethod, int bci, StampPair returnStamp, ValueNode... arguments) {
  49         super(c, invokeKind, targetMethod, bci, returnStamp, arguments);
  50     }
  51 
  52     /**
  53      * This method should return either a constant that represents the result of the function, or
  54      * null if no such result could be determined.
  55      */
  56     protected abstract JavaConstant evaluate(JavaConstant param, MetaAccessProvider metaAccess);
  57 
  58     @Override
  59     public Node canonical(CanonicalizerTool tool) {
  60         if (tool.allUsagesAvailable() && hasNoUsages()) {
  61             return null;
  62         } else {
  63             ValueNode param = arguments.get(0);
  64             if (param.isConstant()) {
  65                 JavaConstant constant = evaluate(param.asJavaConstant(), tool.getMetaAccess());
  66                 if (constant != null) {
  67                     return ConstantNode.forConstant(constant, tool.getMetaAccess());
  68                 }
  69             }
  70         }
  71         return this;
  72     }
  73 }