1 /*
   2  * Copyright (c) 2012, 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 com.oracle.graal.hotspot.replacements;
  24 
  25 import com.oracle.graal.api.code.*;
  26 import com.oracle.graal.api.meta.*;
  27 import com.oracle.graal.compiler.common.type.*;
  28 import com.oracle.graal.graph.spi.*;
  29 import com.oracle.graal.nodeinfo.*;
  30 import com.oracle.graal.nodes.*;
  31 import com.oracle.graal.nodes.calc.*;
  32 import com.oracle.graal.nodes.spi.*;
  33 
  34 /**
  35  * Count the number of leading zeros.
  36  */
  37 @NodeInfo
  38 public class CountLeadingZerosNode extends UnaryNode implements LIRLowerable {
  39 
  40     public static CountLeadingZerosNode create(ValueNode value) {
  41         return new CountLeadingZerosNode(value);
  42     }
  43 
  44     protected CountLeadingZerosNode(ValueNode value) {
  45         super(StampFactory.forInteger(Kind.Int, 0, ((PrimitiveStamp) value.stamp()).getBits()), value);
  46         assert value.getKind() == Kind.Int || value.getKind() == Kind.Long;
  47     }
  48 
  49     @Override
  50     public boolean inferStamp() {
  51         IntegerStamp valueStamp = (IntegerStamp) getValue().stamp();
  52         long mask = CodeUtil.mask(valueStamp.getBits());
  53         int min = Long.numberOfLeadingZeros(valueStamp.upMask() & mask);
  54         int max = Long.numberOfLeadingZeros(valueStamp.downMask() & mask);
  55         return updateStamp(StampFactory.forInteger(Kind.Int, min, max));
  56     }
  57 
  58     @Override
  59     public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) {
  60         if (forValue.isConstant()) {
  61             JavaConstant c = forValue.asJavaConstant();
  62             if (forValue.getKind() == Kind.Int) {
  63                 return ConstantNode.forInt(Integer.numberOfLeadingZeros(c.asInt()));
  64             } else {
  65                 return ConstantNode.forInt(Long.numberOfLeadingZeros(c.asLong()));
  66             }
  67         }
  68         return this;
  69     }
  70 
  71     /**
  72      * Raw intrinsic for lzcntq instruction.
  73      *
  74      * @param v
  75      * @return number of trailing zeros
  76      */
  77     @NodeIntrinsic
  78     public static native int count(long v);
  79 
  80     /**
  81      * Raw intrinsic for lzcntl instruction.
  82      *
  83      * @param v
  84      * @return number of trailing zeros
  85      */
  86     @NodeIntrinsic
  87     public static native int count(int v);
  88 
  89     @Override
  90     public void generate(NodeLIRBuilderTool gen) {
  91         Value result = gen.getLIRGeneratorTool().emitCountLeadingZeros(gen.operand(getValue()));
  92         gen.setResult(this, result);
  93     }
  94 }