| /* |
| * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package org.graalvm.compiler.replacements.nodes; |
| |
| import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_3; |
| import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1; |
| |
| import org.graalvm.compiler.core.common.type.IntegerStamp; |
| import org.graalvm.compiler.core.common.type.PrimitiveStamp; |
| import org.graalvm.compiler.core.common.type.Stamp; |
| import org.graalvm.compiler.core.common.type.StampFactory; |
| import org.graalvm.compiler.graph.NodeClass; |
| import org.graalvm.compiler.graph.spi.CanonicalizerTool; |
| import org.graalvm.compiler.lir.gen.ArithmeticLIRGeneratorTool; |
| import org.graalvm.compiler.nodeinfo.NodeInfo; |
| import org.graalvm.compiler.nodes.ConstantNode; |
| import org.graalvm.compiler.nodes.ValueNode; |
| import org.graalvm.compiler.nodes.calc.UnaryNode; |
| import org.graalvm.compiler.nodes.spi.ArithmeticLIRLowerable; |
| import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool; |
| |
| import jdk.vm.ci.code.CodeUtil; |
| import jdk.vm.ci.meta.JavaConstant; |
| import jdk.vm.ci.meta.JavaKind; |
| |
| /** |
| * Determines the index of the most significant "1" bit. Note that the result is undefined if the |
| * input is zero. |
| */ |
| @NodeInfo(cycles = CYCLES_3, size = SIZE_1) |
| public final class BitScanReverseNode extends UnaryNode implements ArithmeticLIRLowerable { |
| |
| public static final NodeClass<BitScanReverseNode> TYPE = NodeClass.create(BitScanReverseNode.class); |
| |
| public BitScanReverseNode(ValueNode value) { |
| super(TYPE, StampFactory.forInteger(JavaKind.Int, 0, ((PrimitiveStamp) value.stamp()).getBits()), value); |
| assert value.getStackKind() == JavaKind.Int || value.getStackKind() == JavaKind.Long; |
| } |
| |
| @Override |
| public Stamp foldStamp(Stamp newStamp) { |
| assert newStamp.isCompatible(getValue().stamp()); |
| IntegerStamp valueStamp = (IntegerStamp) newStamp; |
| int min; |
| int max; |
| long mask = CodeUtil.mask(valueStamp.getBits()); |
| int lastAlwaysSetBit = scan(valueStamp.downMask() & mask); |
| if (lastAlwaysSetBit == -1) { |
| int firstMaybeSetBit = BitScanForwardNode.scan(valueStamp.upMask() & mask); |
| min = firstMaybeSetBit; |
| } else { |
| min = lastAlwaysSetBit; |
| } |
| int lastMaybeSetBit = scan(valueStamp.upMask() & mask); |
| max = lastMaybeSetBit; |
| return StampFactory.forInteger(JavaKind.Int, min, max); |
| } |
| |
| @Override |
| public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { |
| if (forValue.isConstant()) { |
| JavaConstant c = forValue.asJavaConstant(); |
| if (c.asLong() != 0) { |
| return ConstantNode.forInt(forValue.getStackKind() == JavaKind.Int ? scan(c.asInt()) : scan(c.asLong())); |
| } |
| } |
| return this; |
| } |
| |
| /** |
| * Utility method with defined return value for 0. |
| * |
| * @param v |
| * @return index of first set bit or -1 if {@code v} == 0. |
| */ |
| public static int scan(long v) { |
| return 63 - Long.numberOfLeadingZeros(v); |
| } |
| |
| /** |
| * Utility method with defined return value for 0. |
| * |
| * @param v |
| * @return index of first set bit or -1 if {@code v} == 0. |
| */ |
| public static int scan(int v) { |
| return 31 - Integer.numberOfLeadingZeros(v); |
| } |
| |
| /** |
| * Raw intrinsic for bsr instruction. |
| * |
| * @param v |
| * @return index of first set bit or an undefined value if {@code v} == 0. |
| */ |
| @NodeIntrinsic |
| public static native int unsafeScan(int v); |
| |
| /** |
| * Raw intrinsic for bsr instruction. |
| * |
| * @param v |
| * @return index of first set bit or an undefined value if {@code v} == 0. |
| */ |
| @NodeIntrinsic |
| public static native int unsafeScan(long v); |
| |
| @Override |
| public void generate(NodeLIRBuilderTool builder, ArithmeticLIRGeneratorTool gen) { |
| builder.setResult(this, gen.emitBitScanReverse(builder.operand(getValue()))); |
| } |
| |
| } |