Mercurial > hg > truffle
view graal/com.oracle.graal.replacements.amd64/src/com/oracle/graal/replacements/amd64/AMD64CountLeadingZerosNode.java @ 18704:0ce6ee3d7a98
lzcnt inferStamp reports too large values for Integer.numberOfLeadingZeros
author | Tom Rodriguez <tom.rodriguez@oracle.com> |
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date | Tue, 16 Dec 2014 19:26:38 -0800 |
parents | fe0db662e982 |
children | f57d86eb036f |
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/* * Copyright (c) 2012, 2014, 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 com.oracle.graal.replacements.amd64; import com.oracle.graal.api.code.*; import com.oracle.graal.api.meta.*; import com.oracle.graal.compiler.common.type.*; import com.oracle.graal.graph.spi.*; import com.oracle.graal.nodeinfo.*; import com.oracle.graal.nodes.*; import com.oracle.graal.nodes.calc.*; import com.oracle.graal.nodes.spi.*; /** * Count the number of leading zeros. */ @NodeInfo public class AMD64CountLeadingZerosNode extends UnaryNode implements LIRLowerable { public static AMD64CountLeadingZerosNode create(ValueNode value) { return new AMD64CountLeadingZerosNode(value); } protected AMD64CountLeadingZerosNode(ValueNode value) { super(StampFactory.forInteger(Kind.Int, 0, ((PrimitiveStamp) value.stamp()).getBits()), value); assert value.getKind() == Kind.Int || value.getKind() == Kind.Long; } @Override public boolean inferStamp() { assert value.getKind() == Kind.Int || value.getKind() == Kind.Long; IntegerStamp valueStamp = (IntegerStamp) getValue().stamp(); long mask = CodeUtil.mask(valueStamp.getBits()); // Don't count zeros from the mask in the result. int adjust = Long.numberOfLeadingZeros(mask); assert adjust == 0 || adjust == 32; int min = Long.numberOfLeadingZeros(valueStamp.upMask() & mask) - adjust; int max = Long.numberOfLeadingZeros(valueStamp.downMask() & mask) - adjust; return updateStamp(StampFactory.forInteger(Kind.Int, min, max)); } @Override public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { if (forValue.isConstant()) { JavaConstant c = forValue.asJavaConstant(); if (forValue.getKind() == Kind.Int) { return ConstantNode.forInt(Integer.numberOfLeadingZeros(c.asInt())); } else { return ConstantNode.forInt(Long.numberOfLeadingZeros(c.asLong())); } } return this; } /** * Raw intrinsic for lzcntq instruction. * * @param v * @return number of trailing zeros */ @NodeIntrinsic public static native int count(long v); /** * Raw intrinsic for lzcntl instruction. * * @param v * @return number of trailing zeros */ @NodeIntrinsic public static native int count(int v); @Override public void generate(NodeLIRBuilderTool gen) { Value result = gen.getLIRGeneratorTool().emitCountLeadingZeros(gen.operand(getValue())); gen.setResult(this, result); } }