| /* |
| * Copyright (c) 2016, 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 |
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| * questions. |
| */ |
| |
| /** |
| * @test |
| * @bug 8150804 |
| * @summary Tests elimination of Phi nodes without losing type information. |
| * |
| * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement |
| * compiler.types.TestPhiElimination |
| */ |
| |
| package compiler.types; |
| |
| public class TestPhiElimination { |
| /* |
| A::get() is inlined into test(obj) producing the following graph: |
| |
| Parm (obj) |
| TestPhiElimination |
| | |
| CastPP |
| TestPhiElimination:NotNull |
| | |
| CheckCastPP |
| A:NotNull |
| / \ |
| CheckCastPP | |
| A:NotNull | |
| \ / |
| Phi |
| A |
| | |
| Safepoint |
| |
| PhiNode::ideal() then replaces the Phi by a CheckCastPP: |
| |
| Parm (obj) |
| TestPhiElimination |
| | |
| CheckCastPP |
| A |
| | |
| Safepoint |
| |
| losing the :NotNull information. Therefore, we cannot prove that obj != null |
| when accessing a field and add an uncommon trap. Since obj is used as monitor, we |
| set it to TOP in the uncommon trap branch and later fail in Process_OopMap_Node |
| because the monitor object is TOP. |
| */ |
| public Object test(TestPhiElimination obj) { |
| if (obj instanceof A) { |
| return ((A) obj).get(); |
| } |
| return null; |
| } |
| |
| static public void main(String[] args) { |
| TestPhiElimination t = new TestPhiElimination(); |
| |
| // Warmup |
| B b = new B(); |
| for (int i = 0; i < 1_000; ++i) { |
| t.test(b); |
| } |
| |
| // Compile |
| A a = new A(); |
| for (int i = 0; i < 20_000; ++i) { |
| if (i % 2 == 0) { |
| a.f = null; |
| } |
| t.test(a); |
| } |
| } |
| |
| static class A extends TestPhiElimination { |
| public Object f; |
| |
| public A create() { |
| return new A(); |
| } |
| |
| public synchronized Object get() { |
| if (f == null) { |
| f = create(); |
| } |
| return f; |
| } |
| } |
| |
| static class B extends A { } |
| } |