83 lines
3.3 KiB
Java
83 lines
3.3 KiB
Java
/*
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* Copyright (c) 2022, 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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* @requires vm.compiler2.enabled
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* @bug 8279837
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* @summary Tests infinite loop with region head in iteration split.
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* @run main/othervm -Xcomp -XX:-TieredCompilation
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* -XX:CompileCommand=compileonly,compiler.loopopts.TestIterationSplitWithRegionHead::test
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* -XX:CompileCommand=dontinline,compiler.loopopts.TestIterationSplitWithRegionHead::*
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* compiler.loopopts.TestIterationSplitWithRegionHead
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*/
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package compiler.loopopts;
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public class TestIterationSplitWithRegionHead {
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static boolean flagFalse = false;
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public static void main(String[] args) {
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test();
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}
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public static void test() {
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// 1) The loop tree is built. We find that nested loop N2 is an infinite loop and add a NeverBranch
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// to the inner loop to make it reachable. But the current loop tree does not have N2, yet. The
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// resulting loop tree is:
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//
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// Loop: N0/N0 has_call has_sfpt
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// Loop: N77/N121 has_call // N1 outer
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// Loop: N77/N111 has_call sfpts={ 111 97 } // N1 inner
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//
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// 2) beautify_loops() finds that the outer loop head of N1 is shared and thus adds a new region
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// in merge_many_backedges(). As a result, the loop tree is built again. This time, the NeverBranch
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// in the inner loop of N2 allows that a loop tree can be built for it:
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//
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// Loop: N0/N0 has_call has_sfpt
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// Loop: N216/N213 limit_check profile_predicated predicated has_call sfpts={ 111 97 } // N1 shared loop head
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// Loop: N196/N201 sfpts={ 201 } // N2 inner loop now discovered with the new NeverBranch
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//
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// However, a LoopNode is only added by beautify_loops() which won't be called until the next iteration of loop opts.
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// This means that we have a Region node (N196) as head in the loop tree which cannot be handled by iteration_split_impl()
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// resulting in an assertion failure.
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// Nested loop N1
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while (flagFalse) {
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while (dontInlineFalse()) {
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}
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}
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dontInlineFalse();
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// Nested loop N2
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while (flagFalse) {
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while (true) ; // Detected as infinite inner loop by C2 -> NeverBranch added
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}
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}
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public static boolean dontInlineFalse() {
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return false;
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}
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}
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