101 lines
4.0 KiB
Java
101 lines
4.0 KiB
Java
/*
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* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test TestIntegerComparison
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* @bug 8043284 8042786
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* @summary Tests optimizations of signed and unsigned integer comparison.
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*
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* @run main/othervm -Xcomp
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* -XX:CompileCommand=compileonly,compiler.integerArithmetic.TestIntegerComparison::testSigned
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* -XX:CompileCommand=compileonly,compiler.integerArithmetic.TestIntegerComparison::testUnsigned
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* compiler.integerArithmetic.TestIntegerComparison
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*/
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package compiler.integerArithmetic;
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public class TestIntegerComparison {
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/**
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* Tests optimization of signed integer comparison (see BoolNode::Ideal).
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* The body of the if statement is unreachable and should not be compiled.
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*
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* @param c Character (value in the integer range [0, 65535])
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*/
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public static void testSigned(char c) {
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// The following addition may overflow. The result is in one
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// of the two ranges [IntMax] and [IntMin, IntMin + CharMax - 1].
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int result = c + Integer.MAX_VALUE;
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// CmpINode has to consider both result ranges instead of only
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// the general [IntMin, IntMax] range to be able to prove that
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// result is always unequal to CharMax.
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if (result == Character.MAX_VALUE) {
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// Unreachable
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throw new RuntimeException("Should not reach here!");
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}
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}
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/**
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* Tests optimization of unsigned integer comparison (see CmpUNode::Value).
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* The body of the if statement is unreachable and should not be compiled.
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*
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* @param c Character (value in the integer range [0, 65535])
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*/
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public static void testUnsigned(char c) {
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/*
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* The following if statement consisting of two CmpIs is replaced
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* by a CmpU during optimization (see 'IfNode::fold_compares').
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*
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* The signed (lo < i) and (i < hi) are replaced by the unsigned
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* (i - (lo+1) < hi - (lo+1)). In this case the unsigned comparison
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* equals (result - 2) < 98 leading to the following CmpUNode:
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*
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* CmpU (AddI result, -2) 98
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*
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* With the value of result this is simplified to:
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*
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* CmpU (AddI c, -(CharMax - IntMin)) 98
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*
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* The subtraction may underflow. The result is in one of the two
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* ranges [IntMin], [IntMax - CharMax + 1]. Both ranges have to be
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* considered instead of only the general [IntMin, IntMax] to prove
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* that due to the overflow the signed comparison result < 98 is
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* always false.
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*/
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int result = c - (Character.MAX_VALUE - Integer.MIN_VALUE) + 2;
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if (1 < result && result < 100) {
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// Unreachable
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throw new RuntimeException("Should not reach here!");
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}
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}
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/**
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* Tests optimizations of signed and unsigned integer comparison.
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*/
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public static void main(String[] args) {
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// We use characters to get a limited integer range for free
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for (int i = Character.MIN_VALUE; i <= Character.MAX_VALUE; ++i) {
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testSigned((char) i);
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testUnsigned((char) i);
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}
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}
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}
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