| /* |
| * Copyright (c) 2011, 2016, 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.core.common.type; |
| |
| import org.graalvm.compiler.core.common.LIRKind; |
| import org.graalvm.compiler.core.common.spi.LIRKindTool; |
| |
| import jdk.vm.ci.meta.Constant; |
| import jdk.vm.ci.meta.JavaKind; |
| import jdk.vm.ci.meta.MemoryAccessProvider; |
| import jdk.vm.ci.meta.MetaAccessProvider; |
| import jdk.vm.ci.meta.ResolvedJavaType; |
| |
| /** |
| * 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).isEmpty(); |
| } |
| |
| /** |
| * Gets a Java {@link JavaKind} that can be used to store a value of this stamp on the Java |
| * bytecode stack. Returns {@link JavaKind#Illegal} if a value of this stamp can not be stored |
| * on the bytecode stack. |
| */ |
| public abstract JavaKind 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 #empty()} is the neutral element of the {@link #meet(Stamp)} operation. |
| */ |
| public abstract Stamp empty(); |
| |
| /** |
| * 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); |
| |
| /** |
| * Check that the constant {@code other} is compatible with this stamp. |
| * |
| * @param constant |
| */ |
| public abstract boolean isCompatible(Constant constant); |
| |
| /** |
| * Test whether this stamp has legal values. |
| */ |
| public abstract boolean hasValues(); |
| |
| /** |
| * Tests whether this stamp represents an illegal value. |
| */ |
| public final boolean isEmpty() { |
| return !hasValues(); |
| } |
| |
| /** |
| * 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; |
| } |
| |
| /** |
| * Read a value of this stamp from memory. |
| */ |
| 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 a stamp equal to this. |
| * |
| * @param other the stamp that should be used to improve this stamp |
| * @return the newly improved stamp or a stamp equal to {@code this} if an improvement was not |
| * possible |
| */ |
| public abstract Stamp improveWith(Stamp other); |
| |
| /** |
| * 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 or {@code null} if an improvement was not possible |
| */ |
| public final Stamp tryImproveWith(Stamp other) { |
| Stamp improved = improveWith(other); |
| if (improved.equals(this)) { |
| return null; |
| } |
| return improved; |
| } |
| |
| public boolean neverDistinct(Stamp other) { |
| Constant constant = this.asConstant(); |
| if (constant != null) { |
| Constant otherConstant = other.asConstant(); |
| return otherConstant != null && constant.equals(otherConstant); |
| } |
| return false; |
| } |
| } |