Mercurial > hg > graal-jvmci-8
diff graal/Compiler/src/com/sun/c1x/ir/NullCheck.java @ 2507:9ec15d6914ca
Pull over of compiler from maxine repository.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 27 Apr 2011 11:43:22 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/Compiler/src/com/sun/c1x/ir/NullCheck.java Wed Apr 27 11:43:22 2011 +0200 @@ -0,0 +1,119 @@ +/* + * Copyright (c) 2009, 2011, 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.sun.c1x.ir; + +import com.sun.c1x.debug.*; +import com.sun.c1x.util.*; +import com.sun.c1x.value.*; +import com.sun.cri.bytecode.*; +import com.sun.cri.ri.*; + +/** + * The {@code NullCheck} class represents an explicit null check instruction. + * + * @author Ben L. Titzer + */ +public final class NullCheck extends StateSplit { + + Value object; + + /** + * Constructs a new NullCheck instruction. + * @param obj the instruction producing the object to check against null + * @param stateBefore the state before executing the null check + */ + public NullCheck(Value obj, FrameState stateBefore) { + super(obj.kind, stateBefore); + this.object = obj; + setFlag(Flag.NonNull); + if (object.isNonNull()) { + eliminateNullCheck(); + } + } + + /** + * Gets the instruction that produces the object tested against null. + * @return the instruction producing the object + */ + public Value object() { + return object; + } + + /** + * Checks whether this instruction can cause a trap. + * @return {@code true} if this instruction can cause a trap + */ + @Override + public boolean canTrap() { + return needsNullCheck(); + } + + @Override + public void inputValuesDo(ValueClosure closure) { + object = closure.apply(object); + } + + @Override + public void accept(ValueVisitor v) { + v.visitNullCheck(this); + } + + @Override + public int valueNumber() { + return Util.hash1(Bytecodes.IFNONNULL, object); + } + + @Override + public boolean valueEqual(Instruction i) { + if (i instanceof NullCheck) { + NullCheck o = (NullCheck) i; + return object == o.object; + } + return false; + } + + @Override + public RiType declaredType() { + // null check does not alter the type of the object + return object.declaredType(); + } + + @Override + public RiType exactType() { + // null check does not alter the type of the object + return object.exactType(); + } + + @Override + public void runtimeCheckCleared() { + clearState(); + } + + @Override + public void print(LogStream out) { + out.print("null_check(").print(object()).print(')'); + if (!canTrap()) { + out.print(" (eliminated)"); + } + } +}