Mercurial > hg > truffle
view graal/com.oracle.graal.compiler.common/src/com/oracle/graal/compiler/common/type/Stamp.java @ 18482:b8a622c3e99f
Move raw memory access operations to a separate interface.
author | Roland Schatz <roland.schatz@oracle.com> |
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date | Thu, 20 Nov 2014 17:00:19 +0100 |
parents | a3a2359ac88e |
children | 1a21e7ced544 |
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/* * Copyright (c) 2011, 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.compiler.common.type; import com.oracle.graal.api.meta.*; import com.oracle.graal.compiler.common.spi.*; /** * A stamp is the basis for a type system. */ public abstract class Stamp { protected Stamp() { } /** * Returns the type of the stamp, guaranteed to be non-null. In some cases, this requires the * lookup of class meta data, therefore the {@link MetaAccessProvider} is mandatory. */ public abstract ResolvedJavaType javaType(MetaAccessProvider metaAccess); public boolean alwaysDistinct(Stamp other) { return !join(other).isLegal(); } /** * Gets a Java {@link Kind} that can be used to store a value of this stamp on the Java bytecode * stack. Returns {@link Kind#Illegal} if a value of this stamp can not be stored on the * bytecode stack. */ public abstract Kind getStackKind(); /** * Gets a platform dependent {@link LIRKind} that can be used to store a value of this stamp. */ public abstract LIRKind getLIRKind(LIRKindTool tool); /** * Returns the union of this stamp and the given stamp. Typically used to create stamps for phi * nodes. * * @param other The stamp that will enlarge this stamp. * @return The union of this stamp and the given stamp. */ public abstract Stamp meet(Stamp other); /** * Returns the intersection of this stamp and the given stamp. * * @param other The stamp that will tighten this stamp. * @return The intersection of this stamp and the given stamp. */ public abstract Stamp join(Stamp other); /** * Returns a stamp of the same kind, but allowing the full value range of the kind. * * {@link #unrestricted()} is the neutral element of the {@link #join(Stamp)} operation. */ public abstract Stamp unrestricted(); /** * Returns a stamp of the same kind, but with no allowed values. * * {@link #illegal()} is the neutral element of the {@link #meet(Stamp)} operation. */ public abstract Stamp illegal(); /** * If it is possible to represent single value stamps of this kind, this method returns the * stamp representing the single value c. stamp.constant(c).asConstant() should be equal to c. * <p> * If it is not possible to represent single value stamps, this method returns a stamp that * includes c, and is otherwise as narrow as possible. */ public abstract Stamp constant(Constant c, MetaAccessProvider meta); /** * Test whether two stamps have the same base type. */ public abstract boolean isCompatible(Stamp other); /** * Test whether this stamp has legal values. */ public abstract boolean isLegal(); /** * If this stamp represents a single value, the methods returns this single value. It returns * null otherwise. * * @return the constant corresponding to the single value of this stamp and null if this stamp * can represent less or more than one value. */ public Constant asConstant() { return null; } public abstract Constant readConstant(MemoryAccessProvider provider, Constant base, long displacement); /** * Tries to improve this stamp with the stamp given as parameter. If successful, returns the new * improved stamp. Otherwise, returns null. * * @param other the stamp that should be used to improve this stamp * @return the newly improved stamp of null if an improvement was not possible */ public Stamp tryImprove(Stamp other) { Stamp newStamp = this.join(other); if (newStamp.equals(this)) { return null; } return newStamp; } }