001/* 002 * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved. 003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 004 * 005 * This code is free software; you can redistribute it and/or modify it 006 * under the terms of the GNU General Public License version 2 only, as 007 * published by the Free Software Foundation. 008 * 009 * This code is distributed in the hope that it will be useful, but WITHOUT 010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 011 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 012 * version 2 for more details (a copy is included in the LICENSE file that 013 * accompanied this code). 014 * 015 * You should have received a copy of the GNU General Public License version 016 * 2 along with this work; if not, write to the Free Software Foundation, 017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 018 * 019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 020 * or visit www.oracle.com if you need additional information or have any 021 * questions. 022 */ 023package com.oracle.graal.compiler.common.type; 024 025import jdk.internal.jvmci.common.*; 026import jdk.internal.jvmci.meta.*; 027 028import com.oracle.graal.compiler.common.spi.*; 029 030/** 031 * Singleton stamp representing the value of type {@code void}. 032 */ 033public final class VoidStamp extends Stamp { 034 035 private VoidStamp() { 036 } 037 038 @Override 039 public Stamp unrestricted() { 040 return this; 041 } 042 043 @Override 044 public Kind getStackKind() { 045 return Kind.Void; 046 } 047 048 @Override 049 public Stamp improveWith(Stamp other) { 050 assert other instanceof VoidStamp; 051 return this; 052 } 053 054 @Override 055 public LIRKind getLIRKind(LIRKindTool tool) { 056 throw JVMCIError.shouldNotReachHere("void stamp has no value"); 057 } 058 059 @Override 060 public ResolvedJavaType javaType(MetaAccessProvider metaAccess) { 061 return metaAccess.lookupJavaType(Void.TYPE); 062 } 063 064 @Override 065 public String toString() { 066 return "void"; 067 } 068 069 @Override 070 public boolean alwaysDistinct(Stamp other) { 071 return this != other; 072 } 073 074 @Override 075 public Stamp meet(Stamp other) { 076 assert other instanceof VoidStamp; 077 return this; 078 } 079 080 @Override 081 public Stamp join(Stamp other) { 082 assert other instanceof VoidStamp; 083 return this; 084 } 085 086 @Override 087 public boolean isCompatible(Stamp stamp) { 088 return stamp instanceof VoidStamp; 089 } 090 091 @Override 092 public Stamp empty() { 093 // the void stamp is always empty 094 return this; 095 } 096 097 @Override 098 public boolean hasValues() { 099 return false; 100 } 101 102 @Override 103 public Constant readConstant(MemoryAccessProvider provider, Constant base, long displacement) { 104 throw JVMCIError.shouldNotReachHere("can't read values of void stamp"); 105 } 106 107 @Override 108 public Stamp constant(Constant c, MetaAccessProvider meta) { 109 throw JVMCIError.shouldNotReachHere("void stamp has no value"); 110 } 111 112 private static final VoidStamp instance = new VoidStamp(); 113 114 static VoidStamp getInstance() { 115 return instance; 116 } 117}