Mercurial > hg > graal-jvmci-8
diff graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/BooleanConditionProfile.java @ 16828:2834af86f398
Truffle: new condition profile primitives.
author | Christian Humer <christian.humer@gmail.com> |
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date | Wed, 13 Aug 2014 20:44:36 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/BooleanConditionProfile.java Wed Aug 13 20:44:36 2014 +0200 @@ -0,0 +1,84 @@ +/* + * Copyright (c) 2013, 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. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * 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.truffle.api.utilities; + +import com.oracle.truffle.api.*; +import com.oracle.truffle.api.CompilerDirectives.*; + +/** + * Utility class to speculate on conditions to be never true or to be never false. Condition + * profiles are intended to be used as part of if conditions. + * + * Example usage: + * + * <pre> + * private final ConditionProfile zero = new BooleanConditionProfile(); + * + * int value = ...; + * if (zero.profile(value == 0)) { + * return 0; + * } else { + * return value; + * } + * + * </pre> + * + * @see ConditionProfile + * @see IntegerConditionProfile + */ +public class BooleanConditionProfile extends ConditionProfile { + + @CompilationFinal private boolean wasTrue; + @CompilationFinal private boolean wasFalse; + + @Override + public boolean profile(boolean value) { + if (value) { + if (!wasTrue) { + CompilerDirectives.transferToInterpreterAndInvalidate(); + wasTrue = true; + } + } else { + if (!wasFalse) { + CompilerDirectives.transferToInterpreterAndInvalidate(); + wasFalse = true; + } + } + return value; + } + + public boolean wasTrue() { + return wasTrue; + } + + public boolean wasFalse() { + return wasFalse; + } + + @Override + public String toString() { + return String.format("%s(wasTrue=%s, wasFalse=%s)@%x", getClass().getSimpleName(), wasTrue, wasFalse, hashCode()); + } +}