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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package org.graalvm.compiler.nodes.calc;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_1;

import org.graalvm.compiler.core.common.type.ArithmeticOpTable;
import org.graalvm.compiler.core.common.type.ArithmeticOpTable.IntegerConvertOp;
import org.graalvm.compiler.core.common.type.ArithmeticOpTable.IntegerConvertOp.Narrow;
import org.graalvm.compiler.core.common.type.ArithmeticOpTable.IntegerConvertOp.SignExtend;
import org.graalvm.compiler.core.common.type.PrimitiveStamp;
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.ValueNode;
import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;

The NarrowNode converts an integer to a narrower integer.
/** * The {@code NarrowNode} converts an integer to a narrower integer. */
@NodeInfo(cycles = CYCLES_1) public final class NarrowNode extends IntegerConvertNode<Narrow, SignExtend> { public static final NodeClass<NarrowNode> TYPE = NodeClass.create(NarrowNode.class); public NarrowNode(ValueNode input, int resultBits) { this(input, PrimitiveStamp.getBits(input.stamp()), resultBits); assert 0 < resultBits && resultBits <= PrimitiveStamp.getBits(input.stamp()); } public NarrowNode(ValueNode input, int inputBits, int resultBits) { super(TYPE, ArithmeticOpTable::getNarrow, ArithmeticOpTable::getSignExtend, inputBits, resultBits, input); } public static ValueNode create(ValueNode input, int resultBits) { return create(input, PrimitiveStamp.getBits(input.stamp()), resultBits); } public static ValueNode create(ValueNode input, int inputBits, int resultBits) { IntegerConvertOp<Narrow> signExtend = ArithmeticOpTable.forStamp(input.stamp()).getNarrow(); ValueNode synonym = findSynonym(signExtend, input, inputBits, resultBits, signExtend.foldStamp(inputBits, resultBits, input.stamp())); if (synonym != null) { return synonym; } else { return new NarrowNode(input, inputBits, resultBits); } } @Override public boolean isLossless() { return false; } @Override public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { ValueNode ret = super.canonical(tool, forValue); if (ret != this) { return ret; } if (forValue instanceof NarrowNode) { // zzzzzzzz yyyyxxxx -(narrow)-> yyyyxxxx -(narrow)-> xxxx // ==> zzzzzzzz yyyyxxxx -(narrow)-> xxxx NarrowNode other = (NarrowNode) forValue; return new NarrowNode(other.getValue(), other.getInputBits(), getResultBits()); } else if (forValue instanceof IntegerConvertNode) { // SignExtendNode or ZeroExtendNode IntegerConvertNode<?, ?> other = (IntegerConvertNode<?, ?>) forValue; if (other.getValue().getUsageCount() == 1 && other.getUsageCount() > 1) { // Do not perform if this will introduce a new live value. // If the original value's usage count is > 1, there is already another user. // If the convert's usage count is <=1, it will be dead code eliminated. return this; } if (getResultBits() == other.getInputBits()) { // xxxx -(extend)-> yyyy xxxx -(narrow)-> xxxx // ==> no-op return other.getValue(); } else if (getResultBits() < other.getInputBits()) { // yyyyxxxx -(extend)-> zzzzzzzz yyyyxxxx -(narrow)-> xxxx // ==> yyyyxxxx -(narrow)-> xxxx return new NarrowNode(other.getValue(), other.getInputBits(), getResultBits()); } else { if (other instanceof SignExtendNode) { // sxxx -(sign-extend)-> ssssssss sssssxxx -(narrow)-> sssssxxx // ==> sxxx -(sign-extend)-> sssssxxx return new SignExtendNode(other.getValue(), other.getInputBits(), getResultBits()); } else if (other instanceof ZeroExtendNode) { // xxxx -(zero-extend)-> 00000000 00000xxx -(narrow)-> 0000xxxx // ==> xxxx -(zero-extend)-> 0000xxxx return new ZeroExtendNode(other.getValue(), other.getInputBits(), getResultBits()); } } } return this; } @Override public void generate(NodeLIRBuilderTool nodeValueMap, ArithmeticLIRGeneratorTool gen) { nodeValueMap.setResult(this, gen.emitNarrow(nodeValueMap.operand(getValue()), getResultBits())); } }