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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 /*
  27  * @test TestStableChar
  28  * @summary tests on stable fields and arrays
  29  * @library /testlibrary
  30  * @compile -XDignore.symbol.file TestStableChar.java
  31  * @run main ClassFileInstaller
  32  *           java/lang/invoke/TestStableChar
  33  *           java/lang/invoke/TestStableChar$CharStable
  34  *           java/lang/invoke/TestStableChar$StaticCharStable
  35  *           java/lang/invoke/TestStableChar$VolatileCharStable
  36  *           java/lang/invoke/TestStableChar$CharArrayDim1
  37  *           java/lang/invoke/TestStableChar$CharArrayDim2
  38  *           java/lang/invoke/TestStableChar$CharArrayDim3
  39  *           java/lang/invoke/TestStableChar$CharArrayDim4
  40  *           java/lang/invoke/TestStableChar$ObjectArrayLowerDim0
  41  *           java/lang/invoke/TestStableChar$ObjectArrayLowerDim1
  42  *           java/lang/invoke/TestStableChar$NestedStableField
  43  *           java/lang/invoke/TestStableChar$NestedStableField$A
  44  *           java/lang/invoke/TestStableChar$NestedStableField1
  45  *           java/lang/invoke/TestStableChar$NestedStableField1$A
  46  *           java/lang/invoke/TestStableChar$NestedStableField2
  47  *           java/lang/invoke/TestStableChar$NestedStableField2$A
  48  *           java/lang/invoke/TestStableChar$NestedStableField3
  49  *           java/lang/invoke/TestStableChar$NestedStableField3$A
  50  *           java/lang/invoke/TestStableChar$DefaultValue
  51  *           java/lang/invoke/TestStableChar$ObjectArrayLowerDim2
  52  *
  53  * @run main/othervm -Xbootclasspath/a:. -XX:+IgnoreUnrecognizedVMOptions
  54  *                   -XX:+UnlockDiagnosticVMOptions -XX:+FoldStableValues -XX:-UseCompressedOop
  55  *                   -server -XX:-TieredCompilation -Xcomp
  56  *                   -XX:CompileOnly=::get,::get1,::get2,::get3,::get4
  57  *                   java.lang.invoke.TestStableChar
  58  *
  59  * @run main/othervm -Xbootclasspath/a:. -XX:+IgnoreUnrecognizedVMOptions
  60  *                   -XX:+UnlockDiagnosticVMOptions -XX:+FoldStableValues -XX:+UseCompressedOop
  61  *                   -server -XX:-TieredCompilation -Xcomp
  62  *                   -XX:CompileOnly=::get,::get1,::get2,::get3,::get4
  63  *                   java.lang.invoke.TestStableChar
  64  *
  65  * @run main/othervm -Xbootclasspath/a:. -XX:+IgnoreUnrecognizedVMOptions
  66  *                   -XX:+UnlockDiagnosticVMOptions -XX:-FoldStableValues -XX:+UseCompressedOop
  67  *                   -server -XX:-TieredCompilation -Xcomp
  68  *                   -XX:CompileOnly=::get,::get1,::get2,::get3,::get4
  69  *                   java.lang.invoke.TestStableChar
  70  *
  71  * @run main/othervm -Xbootclasspath/a:. -XX:+IgnoreUnrecognizedVMOptions
  72  *                   -XX:+UnlockDiagnosticVMOptions -XX:-FoldStableValues -XX:-UseCompressedOop
  73  *                   -server -XX:-TieredCompilation -Xcomp
  74  *                   -XX:CompileOnly=::get,::get1,::get2,::get3,::get4
  75  *                   java.lang.invoke.TestStableChar
  76  */
  77 package java.lang.invoke;
  78 
  79 import com.sun.management.HotSpotDiagnosticMXBean;
  80 import com.sun.management.VMOption;
  81 import sun.management.ManagementFactoryHelper;
  82 import java.lang.reflect.InvocationTargetException;
  83 
  84 public class TestStableChar {
  85     public static void main(String[] args) throws Exception {
  86         System.out.println("@Stable enabled: "+isStableEnabled);
  87         System.out.println();
  88 
  89         run(DefaultValue.class);
  90         run(CharStable.class);
  91         run(StaticCharStable.class);
  92         run(VolatileCharStable.class);
  93 
  94         // @Stable arrays: Dim 1-4
  95         run(CharArrayDim1.class);
  96         run(CharArrayDim2.class);
  97         run(CharArrayDim3.class);
  98         run(CharArrayDim4.class);
  99 
 100         // @Stable Object field: dynamic arrays
 101         run(ObjectArrayLowerDim0.class);
 102         run(ObjectArrayLowerDim1.class);
 103         run(ObjectArrayLowerDim2.class);
 104 
 105         // Nested @Stable fields
 106         run(NestedStableField.class);
 107         run(NestedStableField1.class);
 108         run(NestedStableField2.class);
 109         run(NestedStableField3.class);
 110 
 111         if (failed) {
 112             throw new Error("TEST FAILED");
 113         }
 114     }
 115 
 116     /* ==================================================== */
 117 
 118     static class DefaultValue {
 119         public @Stable char v;
 120 
 121         public static final DefaultValue c = new DefaultValue();
 122         public static char get() { return c.v; }
 123         public static void test() throws Exception {
 124                        char val1 = get();
 125             c.v = 'a'; char val2 = get();
 126             assertEquals(val1, 0);
 127             assertEquals(val2, 'a');
 128         }
 129     }
 130 
 131     /* ==================================================== */
 132 
 133     static class CharStable {
 134         public @Stable char v;
 135 
 136         public static final CharStable c = new CharStable();
 137         public static char get() { return c.v; }
 138         public static void test() throws Exception {
 139             c.v = 'a'; char val1 = get();
 140             c.v = 'b'; char val2 = get();
 141             assertEquals(val1, 'a');
 142             assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 143         }
 144     }
 145 
 146     /* ==================================================== */
 147 
 148     static class StaticCharStable {
 149         public @Stable char v;
 150 
 151         public static final StaticCharStable c = new StaticCharStable();
 152         public static char get() { return c.v; }
 153         public static void test() throws Exception {
 154             c.v = 'a'; char val1 = get();
 155             c.v = 'b'; char val2 = get();
 156             assertEquals(val1, 'a');
 157             assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 158         }
 159     }
 160 
 161     /* ==================================================== */
 162 
 163     static class VolatileCharStable {
 164         public @Stable volatile char v;
 165 
 166         public static final VolatileCharStable c = new VolatileCharStable();
 167         public static char get() { return c.v; }
 168         public static void test() throws Exception {
 169             c.v = 'a'; char val1 = get();
 170             c.v = 'b'; char val2 = get();
 171             assertEquals(val1, 'a');
 172             assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 173         }
 174     }
 175 
 176     /* ==================================================== */
 177     // @Stable array == field && all components are stable
 178 
 179     static class CharArrayDim1 {
 180         public @Stable char[] v;
 181 
 182         public static final CharArrayDim1 c = new CharArrayDim1();
 183         public static char get() { return c.v[0]; }
 184         public static char get1() { return c.v[10]; }
 185         public static char[] get2() { return c.v; }
 186         public static void test() throws Exception {
 187             {
 188                 c.v = new char[1]; c.v[0] = 'a'; char val1 = get();
 189                                    c.v[0] = 'b'; char val2 = get();
 190                 assertEquals(val1, 'a');
 191                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 192 
 193                 c.v = new char[1]; c.v[0] = 'c'; char val3 = get();
 194                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 195             }
 196 
 197             {
 198                 c.v = new char[20]; c.v[10] = 'a'; char val1 = get1();
 199                                     c.v[10] = 'b'; char val2 = get1();
 200                 assertEquals(val1, 'a');
 201                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 202 
 203                 c.v = new char[20]; c.v[10] = 'c'; char val3 = get1();
 204                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 205             }
 206 
 207             {
 208                 c.v = new char[1]; char[] val1 = get2();
 209                 c.v = new char[1]; char[] val2 = get2();
 210                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 211             }
 212         }
 213     }
 214 
 215     /* ==================================================== */
 216 
 217     static class CharArrayDim2 {
 218         public @Stable char[][] v;
 219 
 220         public static final CharArrayDim2 c = new CharArrayDim2();
 221         public static char get() { return c.v[0][0]; }
 222         public static char[] get1() { return c.v[0]; }
 223         public static char[][] get2() { return c.v; }
 224         public static void test() throws Exception {
 225             {
 226                 c.v = new char[1][1]; c.v[0][0] = 'a'; char val1 = get();
 227                                       c.v[0][0] = 'b'; char val2 = get();
 228                 assertEquals(val1, 'a');
 229                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 230 
 231                 c.v = new char[1][1]; c.v[0][0] = 'c'; char val3 = get();
 232                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 233 
 234                 c.v[0] = new char[1]; c.v[0][0] = 'd'; char val4 = get();
 235                 assertEquals(val4, (isStableEnabled ? 'a' : 'd'));
 236             }
 237 
 238             {
 239                 c.v = new char[1][1]; char[] val1 = get1();
 240                 c.v[0] = new char[1]; char[] val2 = get1();
 241                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 242             }
 243 
 244             {
 245                 c.v = new char[1][1]; char[][] val1 = get2();
 246                 c.v = new char[1][1]; char[][] val2 = get2();
 247                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 248             }
 249         }
 250     }
 251 
 252     /* ==================================================== */
 253 
 254     static class CharArrayDim3 {
 255         public @Stable char[][][] v;
 256 
 257         public static final CharArrayDim3 c = new CharArrayDim3();
 258         public static char get() { return c.v[0][0][0]; }
 259         public static char[] get1() { return c.v[0][0]; }
 260         public static char[][] get2() { return c.v[0]; }
 261         public static char[][][] get3() { return c.v; }
 262         public static void test() throws Exception {
 263             {
 264                 c.v = new char[1][1][1]; c.v[0][0][0] = 'a'; char val1 = get();
 265                                          c.v[0][0][0] = 'b'; char val2 = get();
 266                 assertEquals(val1, 'a');
 267                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 268 
 269                 c.v = new char[1][1][1]; c.v[0][0][0] = 'c'; char val3 = get();
 270                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 271 
 272                 c.v[0] = new char[1][1]; c.v[0][0][0] = 'd'; char val4 = get();
 273                 assertEquals(val4, (isStableEnabled ? 'a' : 'd'));
 274 
 275                 c.v[0][0] = new char[1]; c.v[0][0][0] = 'e'; char val5 = get();
 276                 assertEquals(val5, (isStableEnabled ? 'a' : 'e'));
 277             }
 278 
 279             {
 280                 c.v = new char[1][1][1]; char[] val1 = get1();
 281                 c.v[0][0] = new char[1]; char[] val2 = get1();
 282                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 283             }
 284 
 285             {
 286                 c.v = new char[1][1][1]; char[][] val1 = get2();
 287                 c.v[0] = new char[1][1]; char[][] val2 = get2();
 288                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 289             }
 290 
 291             {
 292                 c.v = new char[1][1][1]; char[][][] val1 = get3();
 293                 c.v = new char[1][1][1]; char[][][] val2 = get3();
 294                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 295             }
 296         }
 297     }
 298 
 299     /* ==================================================== */
 300 
 301     static class CharArrayDim4 {
 302         public @Stable char[][][][] v;
 303 
 304         public static final CharArrayDim4 c = new CharArrayDim4();
 305         public static char get() { return c.v[0][0][0][0]; }
 306         public static char[] get1() { return c.v[0][0][0]; }
 307         public static char[][] get2() { return c.v[0][0]; }
 308         public static char[][][] get3() { return c.v[0]; }
 309         public static char[][][][] get4() { return c.v; }
 310         public static void test() throws Exception {
 311             {
 312                 c.v = new char[1][1][1][1]; c.v[0][0][0][0] = 'a'; char val1 = get();
 313                                             c.v[0][0][0][0] = 'b'; char val2 = get();
 314                 assertEquals(val1, 'a');
 315                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 316 
 317                 c.v = new char[1][1][1][1]; c.v[0][0][0][0] = 'c'; char val3 = get();
 318                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 319 
 320                 c.v[0] = new char[1][1][1]; c.v[0][0][0][0] = 'd'; char val4 = get();
 321                 assertEquals(val4, (isStableEnabled ? 'a' : 'd'));
 322 
 323                 c.v[0][0] = new char[1][1]; c.v[0][0][0][0] = 'e'; char val5 = get();
 324                 assertEquals(val5, (isStableEnabled ? 'a' : 'e'));
 325 
 326                 c.v[0][0][0] = new char[1]; c.v[0][0][0][0] = 'f'; char val6 = get();
 327                 assertEquals(val6, (isStableEnabled ? 'a' : 'f'));
 328             }
 329 
 330             {
 331                 c.v = new char[1][1][1][1]; char[] val1 = get1();
 332                 c.v[0][0][0] = new char[1]; char[] val2 = get1();
 333                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 334             }
 335 
 336             {
 337                 c.v = new char[1][1][1][1]; char[][] val1 = get2();
 338                 c.v[0][0] = new char[1][1]; char[][] val2 = get2();
 339                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 340             }
 341 
 342             {
 343                 c.v = new char[1][1][1][1]; char[][][] val1 = get3();
 344                 c.v[0] = new char[1][1][1]; char[][][] val2 = get3();
 345                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 346             }
 347 
 348             {
 349                 c.v = new char[1][1][1][1]; char[][][][] val1 = get4();
 350                 c.v = new char[1][1][1][1]; char[][][][] val2 = get4();
 351                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 352             }
 353 
 354         }
 355     }
 356 
 357     /* ==================================================== */
 358     // Dynamic Dim is higher than static
 359     static class ObjectArrayLowerDim0 {
 360         public @Stable Object v;
 361 
 362         public static final ObjectArrayLowerDim0 c = new ObjectArrayLowerDim0();
 363         public static char get() { return ((char[])c.v)[0]; }
 364         public static char[] get1() { return (char[])c.v; }
 365 
 366         public static void test() throws Exception {
 367             {
 368                 c.v = new char[1]; ((char[])c.v)[0] = 'a'; char val1 = get();
 369                                    ((char[])c.v)[0] = 'b'; char val2 = get();
 370 
 371                 assertEquals(val1, 'a');
 372                 assertEquals(val2, 'b');
 373             }
 374 
 375             {
 376                 c.v = new char[1]; char[] val1 = get1();
 377                 c.v = new char[1]; char[] val2 = get1();
 378                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 379             }
 380         }
 381     }
 382 
 383     /* ==================================================== */
 384 
 385     static class ObjectArrayLowerDim1 {
 386         public @Stable Object[] v;
 387 
 388         public static final ObjectArrayLowerDim1 c = new ObjectArrayLowerDim1();
 389         public static char get() { return ((char[][])c.v)[0][0]; }
 390         public static char[] get1() { return (char[])(c.v[0]); }
 391         public static Object[] get2() { return c.v; }
 392 
 393         public static void test() throws Exception {
 394             {
 395                 c.v = new char[1][1]; ((char[][])c.v)[0][0] = 'a'; char val1 = get();
 396                                       ((char[][])c.v)[0][0] = 'b'; char val2 = get();
 397 
 398                 assertEquals(val1, 'a');
 399                 assertEquals(val2, 'b');
 400             }
 401 
 402             {
 403                 c.v = new char[1][1]; c.v[0] = new char[0]; char[] val1 = get1();
 404                                       c.v[0] = new char[0]; char[] val2 = get1();
 405 
 406                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 407             }
 408 
 409             {
 410                 c.v = new char[0][0]; Object[] val1 = get2();
 411                 c.v = new char[0][0]; Object[] val2 = get2();
 412 
 413                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 414             }
 415         }
 416     }
 417 
 418     /* ==================================================== */
 419 
 420     static class ObjectArrayLowerDim2 {
 421         public @Stable Object[][] v;
 422 
 423         public static final ObjectArrayLowerDim2 c = new ObjectArrayLowerDim2();
 424         public static char get() { return ((char[][][])c.v)[0][0][0]; }
 425         public static char[] get1() { return (char[])(c.v[0][0]); }
 426         public static char[][] get2() { return (char[][])(c.v[0]); }
 427         public static Object[][] get3() { return c.v; }
 428 
 429         public static void test() throws Exception {
 430             {
 431                 c.v = new char[1][1][1]; ((char[][][])c.v)[0][0][0] = 'a';  char val1 = get();
 432                                          ((char[][][])c.v)[0][0][0] = 'b'; char val2 = get();
 433 
 434                 assertEquals(val1, 'a');
 435                 assertEquals(val2, 'b');
 436             }
 437 
 438             {
 439                 c.v = new char[1][1][1]; c.v[0][0] = new char[0]; char[] val1 = get1();
 440                                          c.v[0][0] = new char[0]; char[] val2 = get1();
 441 
 442                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 443             }
 444 
 445             {
 446                 c.v = new char[1][1][1]; c.v[0] = new char[0][0]; char[][] val1 = get2();
 447                                          c.v[0] = new char[0][0]; char[][] val2 = get2();
 448 
 449                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 450             }
 451 
 452             {
 453                 c.v = new char[0][0][0]; Object[][] val1 = get3();
 454                 c.v = new char[0][0][0]; Object[][] val2 = get3();
 455 
 456                 assertTrue((isStableEnabled ? (val1 == val2) : (val1 != val2)));
 457             }
 458         }
 459     }
 460 
 461     /* ==================================================== */
 462 
 463     static class NestedStableField {
 464         static class A {
 465             public @Stable char a;
 466 
 467         }
 468         public @Stable A v;
 469 
 470         public static final NestedStableField c = new NestedStableField();
 471         public static A get() { return c.v; }
 472         public static char get1() { return get().a; }
 473 
 474         public static void test() throws Exception {
 475             {
 476                 c.v = new A(); c.v.a = 'a'; A val1 = get();
 477                                c.v.a = 'b'; A val2 = get();
 478 
 479                 assertEquals(val1.a, 'b');
 480                 assertEquals(val2.a, 'b');
 481             }
 482 
 483             {
 484                 c.v = new A(); c.v.a = 'a'; char val1 = get1();
 485                                c.v.a = 'b'; char val2 = get1();
 486                 c.v = new A(); c.v.a = 'c'; char val3 = get1();
 487 
 488                 assertEquals(val1, 'a');
 489                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 490                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 491             }
 492         }
 493     }
 494 
 495     /* ==================================================== */
 496 
 497     static class NestedStableField1 {
 498         static class A {
 499             public @Stable char a;
 500             public @Stable A next;
 501         }
 502         public @Stable A v;
 503 
 504         public static final NestedStableField1 c = new NestedStableField1();
 505         public static A get() { return c.v.next.next.next.next.next.next.next; }
 506         public static char get1() { return get().a; }
 507 
 508         public static void test() throws Exception {
 509             {
 510                 c.v = new A(); c.v.next = new A(); c.v.next.next  = c.v;
 511                                c.v.a = 'a'; c.v.next.a = 'a'; A val1 = get();
 512                                c.v.a = 'b'; c.v.next.a = 'b'; A val2 = get();
 513 
 514                 assertEquals(val1.a, 'b');
 515                 assertEquals(val2.a, 'b');
 516             }
 517 
 518             {
 519                 c.v = new A(); c.v.next = c.v;
 520                                c.v.a = 'a'; char val1 = get1();
 521                                c.v.a = 'b'; char val2 = get1();
 522                 c.v = new A(); c.v.next = c.v;
 523                                c.v.a = 'c'; char val3 = get1();
 524 
 525                 assertEquals(val1, 'a');
 526                 assertEquals(val2, (isStableEnabled ? 'a' : 'b'));
 527                 assertEquals(val3, (isStableEnabled ? 'a' : 'c'));
 528             }
 529         }
 530     }
 531    /* ==================================================== */
 532 
 533     static class NestedStableField2 {
 534         static class A {
 535             public @Stable char a;
 536             public @Stable A left;
 537             public         A right;
 538         }
 539 
 540         public @Stable A v;
 541 
 542         public static final NestedStableField2 c = new NestedStableField2();
 543         public static char get() { return c.v.left.left.left.a; }
 544         public static char get1() { return c.v.left.left.right.left.a; }
 545 
 546         public static void test() throws Exception {
 547             {
 548                 c.v = new A(); c.v.left = c.v.right = c.v;
 549                                c.v.a = 'a'; char val1 = get(); char val2 = get1();
 550                                c.v.a = 'b'; char val3 = get(); char val4 = get1();
 551 
 552                 assertEquals(val1, 'a');
 553                 assertEquals(val3, (isStableEnabled ? 'a' : 'b'));
 554 
 555                 assertEquals(val2, 'a');
 556                 assertEquals(val4, 'b');
 557             }
 558         }
 559     }
 560 
 561     /* ==================================================== */
 562 
 563     static class NestedStableField3 {
 564         static class A {
 565             public @Stable char a;
 566             public @Stable A[] left;
 567             public         A[] right;
 568         }
 569 
 570         public @Stable A[] v;
 571 
 572         public static final NestedStableField3 c = new NestedStableField3();
 573         public static char get() { return c.v[0].left[1].left[0].left[1].a; }
 574         public static char get1() { return c.v[1].left[0].left[1].right[0].left[1].a; }
 575 
 576         public static void test() throws Exception {
 577             {
 578                 A elem = new A();
 579                 c.v = new A[] { elem, elem }; c.v[0].left = c.v[0].right = c.v;
 580                                elem.a = 'a'; char val1 = get(); char val2 = get1();
 581                                elem.a = 'b'; char val3 = get(); char val4 = get1();
 582 
 583                 assertEquals(val1, 'a');
 584                 assertEquals(val3, (isStableEnabled ? 'a' : 'b'));
 585 
 586                 assertEquals(val2, 'a');
 587                 assertEquals(val4, 'b');
 588             }
 589         }
 590     }
 591 
 592     /* ==================================================== */
 593     // Auxiliary methods
 594     static void assertEquals(int i, int j) { if (i != j)  throw new AssertionError(i + " != " + j); }
 595     static void assertTrue(boolean b) { if (!b)  throw new AssertionError(); }
 596 
 597     static boolean failed = false;
 598 
 599     public static void run(Class<?> test) {
 600         Throwable ex = null;
 601         System.out.print(test.getName()+": ");
 602         try {
 603             test.getMethod("test").invoke(null);
 604         } catch (InvocationTargetException e) {
 605             ex = e.getCause();
 606         } catch (Throwable e) {
 607             ex = e;
 608         } finally {
 609             if (ex == null) {
 610                 System.out.println("PASSED");
 611             } else {
 612                 failed = true;
 613                 System.out.println("FAILED");
 614                 ex.printStackTrace(System.out);
 615             }
 616         }
 617     }
 618 
 619     static final boolean isStableEnabled;
 620     static {
 621         HotSpotDiagnosticMXBean diagnostic
 622                 = ManagementFactoryHelper.getDiagnosticMXBean();
 623         VMOption tmp;
 624         try {
 625             tmp = diagnostic.getVMOption("FoldStableValues");
 626         } catch (IllegalArgumentException e) {
 627             tmp = null;
 628         }
 629         isStableEnabled = (tmp == null ? false : Boolean.parseBoolean(tmp.getValue()));
 630     }
 631 }