Mercurial > hg > truffle
diff graal/Compiler/src/com/sun/c1x/ir/StateSplit.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/StateSplit.java Wed Apr 27 11:43:22 2011 +0200 @@ -0,0 +1,87 @@ +/* + * 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.value.*; +import com.sun.cri.ci.*; + +/** + * The {@code StateSplit} class is the abstract base class of all instructions + * that store an immutable copy of the frame state. + * + * @author Ben L. Titzer + */ +public abstract class StateSplit extends Instruction { + + /** + * Sentinel denoting an explicitly cleared state. + */ + private static final FrameState CLEARED_STATE = new MutableFrameState(null, -5, 0, 0); + + private FrameState stateBefore; + + /** + * Creates a new state split with the specified value type. + * @param kind the type of the value that this instruction produces + */ + public StateSplit(CiKind kind, FrameState stateBefore) { + super(kind); + this.stateBefore = stateBefore; + } + + /** + * Determines if the state for this instruction has explicitly + * been cleared (as opposed to never initialized). Once explicitly + * cleared, an instruction must not have it state (re)set. + */ + public boolean isStateCleared() { + return stateBefore == CLEARED_STATE; + } + + /** + * Clears the state for this instruction. Once explicitly + * cleared, an instruction must not have it state (re)set. + */ + protected void clearState() { + stateBefore = CLEARED_STATE; + } + + /** + * Records the state of this instruction before it is executed. + * + * @param stateBefore the state + */ + public final void setStateBefore(FrameState stateBefore) { + assert this.stateBefore == null; + this.stateBefore = stateBefore; + } + + /** + * Gets the state for this instruction. + * @return the state + */ + @Override + public final FrameState stateBefore() { + return stateBefore == CLEARED_STATE ? null : stateBefore; + } +}