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 24 25 package org.graalvm.compiler.nodes.calc; 26 27 import org.graalvm.compiler.core.common.type.ArithmeticOpTable; 28 import org.graalvm.compiler.core.common.type.ArithmeticOpTable.ShiftOp.Shr; 29 import org.graalvm.compiler.core.common.type.IntegerStamp; 30 import org.graalvm.compiler.core.common.type.Stamp; 31 import org.graalvm.compiler.graph.NodeClass; 32 import org.graalvm.compiler.graph.spi.CanonicalizerTool; 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.NodeView; 37 import org.graalvm.compiler.nodes.ValueNode; 38 import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool; 39 40 import jdk.vm.ci.code.CodeUtil; 41 42 @NodeInfo(shortName = ">>") 43 public final class RightShiftNode extends ShiftNode<Shr> { 44 45 public static final NodeClass<RightShiftNode> TYPE = NodeClass.create(RightShiftNode.class); 46 47 public RightShiftNode(ValueNode x, ValueNode y) { 48 super(TYPE, ArithmeticOpTable::getShr, x, y); 49 } 50 51 public static ValueNode create(ValueNode x, ValueNode y, NodeView view) { 52 ArithmeticOpTable.ShiftOp<Shr> op = ArithmeticOpTable.forStamp(x.stamp(view)).getShr(); 53 Stamp stamp = op.foldStamp(x.stamp(view), (IntegerStamp) y.stamp(view)); 54 ValueNode value = ShiftNode.canonical(op, stamp, x, y, view); 55 if (value != null) { 56 return value; 57 } 58 59 return canonical(null, op, stamp, x, y, view); 60 } 61 62 @Override 63 public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) { 64 NodeView view = NodeView.from(tool); 65 ValueNode ret = super.canonical(tool, forX, forY); 66 if (ret != this) { 67 return ret; 68 } 69 70 return canonical(this, getArithmeticOp(), stamp(view), forX, forY, view); 71 } 72 73 private static ValueNode canonical(RightShiftNode rightShiftNode, ArithmeticOpTable.ShiftOp<Shr> op, Stamp stamp, ValueNode forX, ValueNode forY, NodeView view) { 74 RightShiftNode self = rightShiftNode; 75 if (forX.stamp(view) instanceof IntegerStamp && ((IntegerStamp) forX.stamp(view)).isPositive()) { 76 return new UnsignedRightShiftNode(forX, forY); 77 } 78 79 if (forY.isConstant()) { 80 int amount = forY.asJavaConstant().asInt(); 81 int originalAmout = amount; 82 int mask = op.getShiftAmountMask(stamp); 83 amount &= mask; 84 if (amount == 0) { 85 return forX; 86 } 87 if (forX instanceof ShiftNode) { 88 ShiftNode<?> other = (ShiftNode<?>) forX; 89 if (other.getY().isConstant()) { 90 int otherAmount = other.getY().asJavaConstant().asInt() & mask; 91 if (other instanceof RightShiftNode) { 92 int total = amount + otherAmount; 93 if (total != (total & mask)) { 94 assert other.getX().stamp(view) instanceof IntegerStamp; 95 IntegerStamp istamp = (IntegerStamp) other.getX().stamp(view); 96 97 if (istamp.isPositive()) { 98 return ConstantNode.forIntegerKind(stamp.getStackKind(), 0); 99 } 100 if (istamp.isStrictlyNegative()) { 101 return ConstantNode.forIntegerKind(stamp.getStackKind(), -1L); 102 } 103 104 /* 105 * if we cannot replace both shifts with a constant, replace them by a 106 * full shift for this kind 107 */ 108 assert total >= mask; 109 return new RightShiftNode(other.getX(), ConstantNode.forInt(mask)); 110 } 111 return new RightShiftNode(other.getX(), ConstantNode.forInt(total)); 112 } 113 } 114 } 115 if (originalAmout != amount) { 116 return new RightShiftNode(forX, ConstantNode.forInt(amount)); 117 } 118 } 119 if (self == null) { 120 self = new RightShiftNode(forX, forY); 121 } 122 return self; 123 } 124 125 @Override 126 public void generate(NodeLIRBuilderTool nodeValueMap, ArithmeticLIRGeneratorTool gen) { 127 nodeValueMap.setResult(this, gen.emitShr(nodeValueMap.operand(getX()), nodeValueMap.operand(getY()))); 128 } 129 130 @Override 131 public boolean isNarrowable(int resultBits) { 132 if (super.isNarrowable(resultBits)) { 133 /* 134 * For signed right shifts, the narrow can be done before the shift if the cut off bits 135 * are all equal to the sign bit of the input. That's equivalent to the condition that 136 * the input is in the signed range of the narrow type. 137 */ 138 IntegerStamp inputStamp = (IntegerStamp) getX().stamp(NodeView.DEFAULT); 139 return CodeUtil.minValue(resultBits) <= inputStamp.lowerBound() && inputStamp.upperBound() <= CodeUtil.maxValue(resultBits); 140 } else { 141 return false; 142 } 143 } 144 }