465f4c1200
Avoids early bailout of capturing a field store to remove unnecessary zeroing in simple methods containing only non-escaping objects. Reviewed-by: roland, thartmann
75 lines
2.9 KiB
Java
75 lines
2.9 KiB
Java
/*
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* Copyright (c) 2019, 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
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* @bug 8231412
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* @summary The enhancement eliminates all allocations in the loop body of test() due to an improved field zeroing elimination dominance check.
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* @run main/othervm -XX:-TieredCompilation -XX:CompileCommand=compileonly,compiler.escapeAnalysis.TestEliminateAllocation::test
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* compiler.escapeAnalysis.TestEliminateAllocation
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*/
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package compiler.escapeAnalysis;
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public class TestEliminateAllocation {
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public static int a = 20;
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public static int b = 30;
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public static int c = 40;
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public void test() {
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int i = 0;
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/*
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* The resulting IR for the loop body contains 2 allocations, one Wrapper and an int array
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* The array field store in the Wrapper object 'wrapper.arr = arr' cannot be capturued due to an early bail out.
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* Therefore, the initial value of wrapper.arr is null.
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* As a result, the escape analysis marks the array allocation as not scalar replaceable:
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* 'wrapper.arr' which is null is merged with the int array object in the assignment 'wrapper.arr = arr'.
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* Both null and the int array are treated as different objects. As a result the array allocation cannot be eliminated.
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*
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* The new enhancement does not bail out early anymore and therefore escape analysis does not mark it as
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* not scalar replaceable. This results in elimination of all allocations in this method.
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*/
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do {
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int[] arr = new int[] { a / b / c };
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Wrapper wrapper = new Wrapper();
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wrapper.setArr(arr);
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i++;
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}
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while (i < 10);
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}
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public static void main(String[] strArr) {
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TestEliminateAllocation _instance = new TestEliminateAllocation();
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for (int i = 0; i < 10_000; i++ ) {
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_instance.test();
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}
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}
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}
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class Wrapper {
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int[] arr;
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void setArr(int... many) { arr = many; }
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}
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