1 /*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 import sun.hotspot.WhiteBox;
25 import sun.hotspot.code.NMethod;
26 import com.oracle.java.testlibrary.Platform;
27
28 import java.lang.reflect.Method;
29 import java.lang.invoke.MethodHandle;
30 import java.lang.invoke.MethodHandles;
31 import java.lang.invoke.MethodType;
32 import java.util.function.BiFunction;
33
34 /*
35 * @test NullCheckDroppingsTest
36 * @bug 8054492
37 * @summary "Casting can result in redundant null checks in generated code"
38 * @library /testlibrary /testlibrary/whitebox /testlibrary/com/oracle/java/testlibrary
39 * @build NullCheckDroppingsTest
40 * @run main ClassFileInstaller sun.hotspot.WhiteBox
41 * sun.hotspot.WhiteBox$WhiteBoxPermission
42 * @run main ClassFileInstaller com.oracle.java.testlibrary.Platform
43 * @run main/othervm -Xbootclasspath/a:. -XX:+IgnoreUnrecognizedVMOptions -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI
44 * -Xmixed -XX:-BackgroundCompilation -XX:-TieredCompilation -XX:CompileThreshold=1000
45 * -XX:CompileCommand=exclude,NullCheckDroppingsTest::main NullCheckDroppingsTest
46 */
47
48 public class NullCheckDroppingsTest {
49
50 private static final WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();
51
52 static final BiFunction<Class, Object, Object> fCast = (c, o) -> c.cast(o);
53
54 static final MethodHandle SET_SSINK;
55 static final MethodHandle MH_CAST;
56
57 static {
58 try {
59 SET_SSINK = MethodHandles.lookup().findSetter(NullCheckDroppingsTest.class, "ssink", String.class);
60 MH_CAST = MethodHandles.lookup().findVirtual(Class.class,
61 "cast",
62 MethodType.methodType(Object.class, Object.class));
63 }
64 catch (Exception e) {
65 throw new Error(e);
66 }
67 }
68
69 static volatile String svalue = "A";
70 static volatile String snull = null;
71
72 String ssink;
73
74 public static void main(String[] args) throws Exception {
75
76 // Only test C2 in Server VM
77 if (!Platform.isServer()) {
78 return;
79 }
80 // Make sure background compilation is disabled
81 if (WHITE_BOX.getBooleanVMFlag("BackgroundCompilation")) {
82 throw new RuntimeException("Background compilation enabled");
83 }
84 // Make sure Tiered compilation is disabled
85 if (WHITE_BOX.getBooleanVMFlag("TieredCompilation")) {
86 throw new RuntimeException("Tiered compilation enabled");
87 }
88
89 Method testOne = NullCheckDroppingsTest.class.getDeclaredMethod("testLoopOne", String.class);
90 Method testTwo = NullCheckDroppingsTest.class.getDeclaredMethod("testLoopTwo", String.class);
91 Method testThree = NullCheckDroppingsTest.class.getDeclaredMethod("testLoopThree", String.class);
92 Method testFour = NullCheckDroppingsTest.class.getDeclaredMethod("testLoopFour", String.class);
93
94 NullCheckDroppingsTest t = new NullCheckDroppingsTest();
95
96 // Ensure testLoopOne is compiled
97 for (int i = 0; i < 3000; i++) {
98 t.testLoopOne(svalue);
99 t.testLoopTwo(svalue);
100 t.testLoopThree(svalue);
101 t.testLoopFour(svalue);
102 }
103 NMethod nm = getNMethod(testOne);
104 // This should cause a de-optimisation
105 // if testLoopOne is compiled with a null-check.
106 t.testLoopOne(snull);
107 checkDeoptimization(testOne, nm);
108
109 nm = getNMethod(testTwo);
110 t.testLoopTwo(snull);
111 checkDeoptimization(testTwo, nm);
112
113 nm = getNMethod(testThree);
114 t.testLoopThree(snull);
115 checkDeoptimization(testThree, nm);
116
117 nm = getNMethod(testFour);
118 t.testLoopFour(snull);
119 checkDeoptimization(testFour, nm);
120 }
121
122 void testLoopOne(String s) {
123 try {
124 ssink = String.class.cast(s);
125 } catch (Throwable t) {
126 throw new Error(t);
127 }
128 }
129
130 void testLoopTwo(String s) {
131 try {
132 ssink = (String) (Object) MH_CAST.invokeExact(String.class, (Object) s);;
133 } catch (Throwable t) {
134 throw new Error(t);
135 }
136 }
137
138 void testLoopThree(String s) {
139 try {
140 SET_SSINK.invokeExact(this, s);
141 } catch (Throwable t) {
142 throw new Error(t);
143 }
144 }
145
146 void testLoopFour(String s) {
147 try {
148 ssink = (String) fCast.apply(String.class, s);
149 } catch (Throwable t) {
150 throw new Error(t);
151 }
152 }
153
154 static NMethod getNMethod(Method test) throws Exception {
155 // Because background compilation is disabled, method should now be compiled
156 if (!WHITE_BOX.isMethodCompiled(test)) {
157 throw new RuntimeException(test + " not compiled");
158 }
159
160 NMethod nm = NMethod.get(test, false); // not OSR nmethod
161 if (nm == null) {
162 throw new RuntimeException(test + " missing nmethod?");
163 }
164 if (nm.comp_level != 4) {
165 throw new RuntimeException(test + " compiled by not C2: " + nm);
166 }
167 return nm;
168 }
169
170 static void checkDeoptimization(Method test, NMethod nmOrig) throws Exception {
171 // Ensure no deoptimization (intrinsic Class.cast() works).
172 if (!WHITE_BOX.isMethodCompiled(test)) {
173 throw new RuntimeException(test + " deoptimized");
174 }
175
176 // Ensure no recompilation.
177 NMethod nm = NMethod.get(test, false); // not OSR nmethod
178 if (nm == null) {
179 throw new RuntimeException(test + " missing nmethod?");
180 }
181 if (nm.comp_level != 4) {
182 throw new RuntimeException(test + " compiled by not C2: " + nm);
183 }
184 if (nm.compile_id != nmOrig.compile_id) {
185 throw new RuntimeException(test + " was recompiled: old nmethod=" + nmOrig + ", new nmethod=" + nm);
186 }
187 }
188 }