1 /* 2 * Copyright (c) 2011, 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.nodes.calc; 24 25 import org.graalvm.compiler.core.common.type.ArithmeticOpTable; 26 import org.graalvm.compiler.core.common.type.ArithmeticOpTable.ShiftOp.UShr; 27 import org.graalvm.compiler.core.common.type.IntegerStamp; 28 import org.graalvm.compiler.graph.NodeClass; 29 import org.graalvm.compiler.graph.spi.CanonicalizerTool; 30 import org.graalvm.compiler.lir.gen.ArithmeticLIRGeneratorTool; 31 import org.graalvm.compiler.nodeinfo.NodeInfo; 32 import org.graalvm.compiler.nodes.ConstantNode; 33 import org.graalvm.compiler.nodes.ValueNode; 34 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool; 35 36 import jdk.vm.ci.meta.JavaKind; 37 38 @NodeInfo(shortName = ">>>") 39 public final class UnsignedRightShiftNode extends ShiftNode<UShr> { 40 41 public static final NodeClass<UnsignedRightShiftNode> TYPE = NodeClass.create(UnsignedRightShiftNode.class); 42 43 public UnsignedRightShiftNode(ValueNode x, ValueNode y) { 44 super(TYPE, ArithmeticOpTable::getUShr, x, y); 45 } 46 47 @Override 48 public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) { 49 ValueNode ret = super.canonical(tool, forX, forY); 50 if (ret != this) { 51 return ret; 52 } 53 54 if (forY.isConstant()) { 55 int amount = forY.asJavaConstant().asInt(); 56 int originalAmout = amount; 57 int mask = getShiftAmountMask(); 58 amount &= mask; 59 if (amount == 0) { 60 return forX; 61 } 62 if (forX instanceof ShiftNode) { 63 ShiftNode<?> other = (ShiftNode<?>) forX; 64 if (other.getY().isConstant()) { 65 int otherAmount = other.getY().asJavaConstant().asInt() & mask; 66 if (other instanceof UnsignedRightShiftNode) { 67 int total = amount + otherAmount; 68 if (total != (total & mask)) { 69 return ConstantNode.forIntegerKind(getStackKind(), 0); 70 } 71 return new UnsignedRightShiftNode(other.getX(), ConstantNode.forInt(total)); 72 } else if (other instanceof LeftShiftNode && otherAmount == amount) { 73 if (getStackKind() == JavaKind.Long) { 74 return new AndNode(other.getX(), ConstantNode.forLong(-1L >>> amount)); 75 } else { 76 assert getStackKind() == JavaKind.Int; 77 return new AndNode(other.getX(), ConstantNode.forInt(-1 >>> amount)); 78 } 79 } 80 } 81 } 82 if (originalAmout != amount) { 83 return new UnsignedRightShiftNode(forX, ConstantNode.forInt(amount)); 84 } 85 } 86 return this; 87 } 88 89 @Override 90 public void generate(NodeLIRBuilderTool nodeValueMap, ArithmeticLIRGeneratorTool gen) { 91 nodeValueMap.setResult(this, gen.emitUShr(nodeValueMap.operand(getX()), nodeValueMap.operand(getY()))); 92 } 93 94 @Override 95 public boolean isNarrowable(int resultBits) { 96 if (super.isNarrowable(resultBits)) { 97 /* 98 * For unsigned right shifts, the narrow can be done before the shift if the cut off 99 * bits are all zero. 100 */ 101 IntegerStamp inputStamp = (IntegerStamp) getX().stamp(); 102 return (inputStamp.upMask() & ~(resultBits - 1)) == 0; 103 } else { 104 return false; 105 } 106 } 107 }