Mercurial > hg > graal-compiler
view graal/com.oracle.truffle.sl/src/com/oracle/truffle/sl/nodes/expression/SLAddNode.java @ 19312:a8d128366ebf
Merge
author | Andreas Woess <andreas.woess@jku.at> |
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date | Thu, 12 Feb 2015 04:01:46 +0100 |
parents | bf846a813688 |
children | b1530a6cce8c |
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/* * Copyright (c) 2012, 2014, 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.oracle.truffle.sl.nodes.expression; import java.math.*; import com.oracle.truffle.api.*; import com.oracle.truffle.api.CompilerDirectives.*; import com.oracle.truffle.api.dsl.*; import com.oracle.truffle.api.nodes.*; import com.oracle.truffle.api.source.*; import com.oracle.truffle.sl.nodes.*; /** * SL node that performs the "+" operation, which performs addition on arbitrary precision numbers, * as well as String concatenation if one of the operands is a String. * <p> * Type specialization on the input values is essential for the performance. This is achieved via * node rewriting: specialized subclasses handle just a single type, so that the generic node that * can handle all types is used only in cases where different types were encountered. The subclasses * are automatically generated by the Truffle DSL. In addition, a {@link SLAddNodeGen factory class} * is generated that provides, e.g., {@link SLAddNodeGen#create node creation}. */ @NodeInfo(shortName = "+") public abstract class SLAddNode extends SLBinaryNode { public SLAddNode(SourceSection src) { super(src); } /** * Specialization for primitive {@code long} values. This is the fast path of the * arbitrary-precision arithmetic. We need to check for overflows of the addition, and switch to * the {@link #add(BigInteger, BigInteger) slow path}. Therefore, we use an * {@link ExactMath#addExact(long, long) addition method that throws an exception on overflow}. * The {@code rewriteOn} attribute on the {@link Specialization} annotation automatically * triggers the node rewriting on the exception. * <p> * In compiled code, {@link ExactMath#addExact(long, long) addExact} is compiled to efficient * machine code that uses the processor's overflow flag. Therefore, this method is compiled to * only two machine code instructions on the fast path. * <p> * This specialization is automatically selected by the Truffle DSL if both the left and right * operand are {@code long} values. */ @Specialization(rewriteOn = ArithmeticException.class) protected long add(long left, long right) { return ExactMath.addExact(left, right); } /** * This is the slow path of the arbitrary-precision arithmetic. The {@link BigInteger} type of * Java is doing everything we need. * <p> * This specialization is automatically selected by the Truffle DSL if both the left and right * operand are {@link BigInteger} values. Because the type system defines an * {@link ImplicitCast implicit conversion} from {@code long} to {@link BigInteger} in * {@link SLTypes#castBigInteger(long)}, this specialization is also taken if the left or the * right operand is a {@code long} value. Because the {@link #add(long, long) long} * specialization} has the {@code rewriteOn} attribute, this specialization is also taken if * both input values are {@code long} values but the primitive addition overflows. */ @Specialization @TruffleBoundary protected BigInteger add(BigInteger left, BigInteger right) { return left.add(right); } /** * Specialization for String concatenation. The SL specification says that String concatenation * works if either the left or the right operand is a String. The non-string operand is * converted then automatically converted to a String. * <p> * To implement these semantics, we tell the Truffle DSL to use a custom guard. The guard * function is defined in {@link #isString this class}, but could also be in any superclass. */ @Specialization(guards = "isString(left, right)") @TruffleBoundary protected String add(Object left, Object right) { return left.toString() + right.toString(); } /** * Guard for String concatenation: returns true if either the left or the right operand is a * {@link String}. */ protected boolean isString(Object a, Object b) { return a instanceof String || b instanceof String; } }