1 /*
   2  * Copyright (c) 2012, 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.
   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.amd64;
  24 
  25 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_3;
  26 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;
  27 
  28 import org.graalvm.compiler.core.common.type.IntegerStamp;
  29 import org.graalvm.compiler.core.common.type.Stamp;
  30 import org.graalvm.compiler.graph.NodeClass;
  31 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
  32 import org.graalvm.compiler.lir.amd64.AMD64ArithmeticLIRGeneratorTool;
  33 import org.graalvm.compiler.lir.gen.ArithmeticLIRGeneratorTool;
  34 import org.graalvm.compiler.nodeinfo.NodeInfo;
  35 import org.graalvm.compiler.nodes.ConstantNode;
  36 import org.graalvm.compiler.nodes.ValueNode;
  37 import org.graalvm.compiler.nodes.calc.UnaryNode;
  38 import org.graalvm.compiler.nodes.spi.ArithmeticLIRLowerable;
  39 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
  40 import org.graalvm.compiler.nodes.type.StampTool;
  41 
  42 import jdk.vm.ci.meta.JavaConstant;
  43 import jdk.vm.ci.meta.JavaKind;
  44 
  45 /**
  46  * Count the number of trailing zeros using the {@code tzcntq} or {@code tzcntl} instructions.
  47  */
  48 @NodeInfo(cycles = CYCLES_3, size = SIZE_1)
  49 public final class AMD64CountTrailingZerosNode extends UnaryNode implements ArithmeticLIRLowerable {
  50     public static final NodeClass<AMD64CountTrailingZerosNode> TYPE = NodeClass.create(AMD64CountTrailingZerosNode.class);
  51 
  52     public AMD64CountTrailingZerosNode(ValueNode value) {
  53         super(TYPE, computeStamp(value.stamp(), value), value);
  54         assert value.getStackKind() == JavaKind.Int || value.getStackKind() == JavaKind.Long;
  55     }
  56 
  57     @Override
  58     public Stamp foldStamp(Stamp newStamp) {
  59         return computeStamp(newStamp, getValue());
  60     }
  61 
  62     static Stamp computeStamp(Stamp newStamp, ValueNode value) {
  63         assert newStamp.isCompatible(value.stamp());
  64         IntegerStamp valueStamp = (IntegerStamp) newStamp;
  65         return StampTool.stampForTrailingZeros(valueStamp);
  66     }
  67 
  68     public static ValueNode tryFold(ValueNode value) {
  69         if (value.isConstant()) {
  70             JavaConstant c = value.asJavaConstant();
  71             if (value.getStackKind() == JavaKind.Int) {
  72                 return ConstantNode.forInt(Integer.numberOfTrailingZeros(c.asInt()));
  73             } else {
  74                 return ConstantNode.forInt(Long.numberOfTrailingZeros(c.asLong()));
  75             }
  76         }
  77         return null;
  78     }
  79 
  80     @Override
  81     public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) {
  82         ValueNode folded = tryFold(forValue);
  83         return folded != null ? folded : this;
  84     }
  85 
  86     @Override
  87     public void generate(NodeLIRBuilderTool builder, ArithmeticLIRGeneratorTool gen) {
  88         builder.setResult(this, ((AMD64ArithmeticLIRGeneratorTool) gen).emitCountTrailingZeros(builder.operand(getValue())));
  89     }
  90 }