1 /*
2 * Copyright (c) 2011, 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 package jdk.vm.ci.hotspot;
25
26 import static jdk.vm.ci.inittimer.InitTimer.timer;
27
28 import java.lang.reflect.Constructor;
29 import java.lang.reflect.Method;
30
31 import jdk.vm.ci.code.InstalledCode;
32 import jdk.vm.ci.code.InvalidInstalledCodeException;
33 import jdk.vm.ci.code.TargetDescription;
34 import jdk.vm.ci.hotspotvmconfig.HotSpotVMField;
35 import jdk.vm.ci.inittimer.InitTimer;
36 import jdk.vm.ci.meta.JavaType;
37 import jdk.vm.ci.meta.ResolvedJavaMethod;
38 import jdk.vm.ci.meta.ResolvedJavaType;
39 import jdk.vm.ci.meta.SpeculationLog;
40 import sun.misc.Unsafe;
41
42 /**
43 * Calls from Java into HotSpot. The behavior of all the methods in this class that take a native
44 * pointer as an argument (e.g., {@link #getSymbol(long)}) is undefined if the argument does not
45 * denote a valid native object.
46 */
47 public final class CompilerToVM {
48 /**
49 * Initializes the native part of the JVMCI runtime.
50 */
51 private static native void registerNatives();
52
53 static {
54 initialize();
55 }
56
57 @SuppressWarnings("try")
58 private static void initialize() {
59 try (InitTimer t = timer("CompilerToVM.registerNatives")) {
60 registerNatives();
61 }
62 }
63
64 /**
65 * Copies the original bytecode of {@code method} into a new byte array and returns it.
66 *
67 * @return a new byte array containing the original bytecode of {@code method}
68 */
69 native byte[] getBytecode(HotSpotResolvedJavaMethodImpl method);
70
71 /**
72 * Gets the number of entries in {@code method}'s exception handler table or 0 if it has not
73 * exception handler table.
74 */
75 native int getExceptionTableLength(HotSpotResolvedJavaMethodImpl method);
76
77 /**
78 * Gets the address of the first entry in {@code method}'s exception handler table.
79 *
80 * Each entry is a native object described by these fields:
81 *
82 * <ul>
83 * <li>{@link HotSpotVMConfig#exceptionTableElementSize}</li>
84 * <li>{@link HotSpotVMConfig#exceptionTableElementStartPcOffset}</li>
85 * <li>{@link HotSpotVMConfig#exceptionTableElementEndPcOffset}</li>
86 * <li>{@link HotSpotVMConfig#exceptionTableElementHandlerPcOffset}</li>
87 * <li>{@link HotSpotVMConfig#exceptionTableElementCatchTypeIndexOffset}
88 * </ul>
89 *
90 * @return 0 if {@code method} has no exception handlers (i.e.
91 * {@code getExceptionTableLength(method) == 0})
92 */
93 native long getExceptionTableStart(HotSpotResolvedJavaMethodImpl method);
94
95 /**
96 * Determines if {@code method} can be inlined. A method may not be inlinable for a number of
97 * reasons such as:
98 * <ul>
99 * <li>a CompileOracle directive may prevent inlining or compilation of methods</li>
100 * <li>the method may have a bytecode breakpoint set</li>
101 * <li>the method may have other bytecode features that require special handling by the VM</li>
102 * </ul>
103 */
104 native boolean canInlineMethod(HotSpotResolvedJavaMethodImpl method);
105
106 /**
107 * Determines if {@code method} should be inlined at any cost. This could be because:
108 * <ul>
109 * <li>a CompileOracle directive may forces inlining of this methods</li>
110 * <li>an annotation forces inlining of this method</li>
111 * </ul>
112 */
113 native boolean shouldInlineMethod(HotSpotResolvedJavaMethodImpl method);
114
115 /**
116 * Used to implement {@link ResolvedJavaType#findUniqueConcreteMethod(ResolvedJavaMethod)}.
117 *
118 * @param method the method on which to base the search
119 * @param actualHolderType the best known type of receiver
120 * @return the method result or 0 is there is no unique concrete method for {@code method}
121 */
122 native HotSpotResolvedJavaMethodImpl findUniqueConcreteMethod(HotSpotResolvedObjectTypeImpl actualHolderType, HotSpotResolvedJavaMethodImpl method);
123
124 /**
125 * Gets the implementor for the interface class {@code type}.
126 *
127 * @return the implementor if there is a single implementor, 0 if there is no implementor, or
128 * {@code type} itself if there is more than one implementor
129 */
130 native HotSpotResolvedObjectTypeImpl getImplementor(HotSpotResolvedObjectTypeImpl type);
131
132 /**
133 * Determines if {@code method} is ignored by security stack walks.
134 */
135 native boolean methodIsIgnoredBySecurityStackWalk(HotSpotResolvedJavaMethodImpl method);
136
137 /**
138 * Converts a name to a type.
139 *
140 * @param name a well formed Java type in {@linkplain JavaType#getName() internal} format
141 * @param accessingClass the context of resolution (must not be null)
142 * @param resolve force resolution to a {@link ResolvedJavaType}. If true, this method will
143 * either return a {@link ResolvedJavaType} or throw an exception
144 * @return the type for {@code name} or 0 if resolution failed and {@code resolve == false}
145 * @throws LinkageError if {@code resolve == true} and the resolution failed
146 */
147 native HotSpotResolvedObjectTypeImpl lookupType(String name, Class<?> accessingClass, boolean resolve);
148
149 /**
150 * Resolves the entry at index {@code cpi} in {@code constantPool} to an object.
151 *
152 * The behavior of this method is undefined if {@code cpi} does not denote one of the following
153 * entry types: {@code JVM_CONSTANT_MethodHandle}, {@code JVM_CONSTANT_MethodHandleInError},
154 * {@code JVM_CONSTANT_MethodType} and {@code JVM_CONSTANT_MethodTypeInError}.
155 */
156 native Object resolveConstantInPool(HotSpotConstantPool constantPool, int cpi);
157
158 /**
159 * Resolves the entry at index {@code cpi} in {@code constantPool} to an object, looking in the
160 * constant pool cache first.
161 *
162 * The behavior of this method is undefined if {@code cpi} does not denote a
163 * {@code JVM_CONSTANT_String} entry.
164 */
165 native Object resolvePossiblyCachedConstantInPool(HotSpotConstantPool constantPool, int cpi);
166
167 /**
168 * Gets the {@code JVM_CONSTANT_NameAndType} index from the entry at index {@code cpi} in
169 * {@code constantPool}.
170 *
171 * The behavior of this method is undefined if {@code cpi} does not denote an entry containing a
172 * {@code JVM_CONSTANT_NameAndType} index.
173 */
174 native int lookupNameAndTypeRefIndexInPool(HotSpotConstantPool constantPool, int cpi);
175
176 /**
177 * Gets the name of the {@code JVM_CONSTANT_NameAndType} entry referenced by another entry
178 * denoted by {@code which} in {@code constantPool}.
179 *
180 * The behavior of this method is undefined if {@code which} does not denote a entry that
181 * references a {@code JVM_CONSTANT_NameAndType} entry.
182 */
183 native String lookupNameInPool(HotSpotConstantPool constantPool, int which);
184
185 /**
186 * Gets the signature of the {@code JVM_CONSTANT_NameAndType} entry referenced by another entry
187 * denoted by {@code which} in {@code constantPool}.
188 *
189 * The behavior of this method is undefined if {@code which} does not denote a entry that
190 * references a {@code JVM_CONSTANT_NameAndType} entry.
191 */
192 native String lookupSignatureInPool(HotSpotConstantPool constantPool, int which);
193
194 /**
195 * Gets the {@code JVM_CONSTANT_Class} index from the entry at index {@code cpi} in
196 * {@code constantPool}.
197 *
198 * The behavior of this method is undefined if {@code cpi} does not denote an entry containing a
199 * {@code JVM_CONSTANT_Class} index.
200 */
201 native int lookupKlassRefIndexInPool(HotSpotConstantPool constantPool, int cpi);
202
203 /**
204 * Looks up a class denoted by the {@code JVM_CONSTANT_Class} entry at index {@code cpi} in
205 * {@code constantPool}. This method does not perform any resolution.
206 *
207 * The behavior of this method is undefined if {@code cpi} does not denote a
208 * {@code JVM_CONSTANT_Class} entry.
209 *
210 * @return the resolved class entry or a String otherwise
211 */
212 native Object lookupKlassInPool(HotSpotConstantPool constantPool, int cpi);
213
214 /**
215 * Looks up a method denoted by the entry at index {@code cpi} in {@code constantPool}. This
216 * method does not perform any resolution.
217 *
218 * The behavior of this method is undefined if {@code cpi} does not denote an entry representing
219 * a method.
220 *
221 * @param opcode the opcode of the instruction for which the lookup is being performed or
222 * {@code -1}. If non-negative, then resolution checks specific to the bytecode it
223 * denotes are performed if the method is already resolved. Should any of these
224 * checks fail, 0 is returned.
225 * @return the resolved method entry, 0 otherwise
226 */
227 native HotSpotResolvedJavaMethodImpl lookupMethodInPool(HotSpotConstantPool constantPool, int cpi, byte opcode);
228
229 /**
230 * Ensures that the type referenced by the specified {@code JVM_CONSTANT_InvokeDynamic} entry at
231 * index {@code cpi} in {@code constantPool} is loaded and initialized.
232 *
233 * The behavior of this method is undefined if {@code cpi} does not denote a
234 * {@code JVM_CONSTANT_InvokeDynamic} entry.
235 */
236 native void resolveInvokeDynamicInPool(HotSpotConstantPool constantPool, int cpi);
237
238 /**
239 * Ensures that the type referenced by the entry for a <a
240 * href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-2.html#jvms-2.9">signature
241 * polymorphic</a> method at index {@code cpi} in {@code constantPool} is loaded and
242 * initialized.
243 *
244 * The behavior of this method is undefined if {@code cpi} does not denote an entry representing
245 * a signature polymorphic method.
246 */
247 native void resolveInvokeHandleInPool(HotSpotConstantPool constantPool, int cpi);
248
249 /**
250 * Gets the resolved type denoted by the entry at index {@code cpi} in {@code constantPool}.
251 *
252 * The behavior of this method is undefined if {@code cpi} does not denote an entry representing
253 * a class.
254 *
255 * @throws LinkageError if resolution failed
256 */
257 native HotSpotResolvedObjectTypeImpl resolveTypeInPool(HotSpotConstantPool constantPool, int cpi) throws LinkageError;
258
259 /**
260 * Looks up and attempts to resolve the {@code JVM_CONSTANT_Field} entry at index {@code cpi} in
261 * {@code constantPool}. The values returned in {@code info} are:
262 *
263 * <pre>
264 * [(int) flags, // only valid if field is resolved
265 * (int) offset] // only valid if field is resolved
266 * </pre>
267 *
268 * The behavior of this method is undefined if {@code cpi} does not denote a
269 * {@code JVM_CONSTANT_Field} entry.
270 *
271 * @param info an array in which the details of the field are returned
272 * @return the type defining the field if resolution is successful, 0 otherwise
273 */
274 native HotSpotResolvedObjectTypeImpl resolveFieldInPool(HotSpotConstantPool constantPool, int cpi, byte opcode, long[] info);
275
276 /**
277 * Converts {@code cpci} from an index into the cache for {@code constantPool} to an index
278 * directly into {@code constantPool}.
279 *
280 * The behavior of this method is undefined if {@code ccpi} is an invalid constant pool cache
281 * index.
282 */
283 native int constantPoolRemapInstructionOperandFromCache(HotSpotConstantPool constantPool, int cpci);
284
285 /**
286 * Gets the appendix object (if any) associated with the entry at index {@code cpi} in
287 * {@code constantPool}.
288 */
289 native Object lookupAppendixInPool(HotSpotConstantPool constantPool, int cpi);
290
291 /**
292 * Installs the result of a compilation into the code cache.
293 *
294 * @param target the target where this code should be installed
295 * @param compiledCode the result of a compilation
296 * @param code the details of the installed CodeBlob are written to this object
297 * @return the outcome of the installation which will be one of
298 * {@link HotSpotVMConfig#codeInstallResultOk},
299 * {@link HotSpotVMConfig#codeInstallResultCacheFull},
300 * {@link HotSpotVMConfig#codeInstallResultCodeTooLarge},
301 * {@link HotSpotVMConfig#codeInstallResultDependenciesFailed} or
302 * {@link HotSpotVMConfig#codeInstallResultDependenciesInvalid}.
303 */
304 public native int installCode(TargetDescription target, HotSpotCompiledCode compiledCode, InstalledCode code, SpeculationLog speculationLog);
305
306 public native int getMetadata(TargetDescription target, HotSpotCompiledCode compiledCode, HotSpotMetaData metaData);
307
308 /**
309 * Notifies the VM of statistics for a completed compilation.
310 *
311 * @param id the identifier of the compilation
312 * @param method the method compiled
313 * @param osr specifies if the compilation was for on-stack-replacement
314 * @param processedBytecodes the number of bytecodes processed during the compilation, including
315 * the bytecodes of all inlined methods
316 * @param time the amount time spent compiling {@code method}
317 * @param timeUnitsPerSecond the granularity of the units for the {@code time} value
318 * @param installedCode the nmethod installed as a result of the compilation
319 */
320 public synchronized native void notifyCompilationStatistics(int id, HotSpotResolvedJavaMethodImpl method, boolean osr, int processedBytecodes, long time, long timeUnitsPerSecond,
321 InstalledCode installedCode);
322
323 /**
324 * Resets all compilation statistics.
325 */
326 public native void resetCompilationStatistics();
327
328 /**
329 * Initializes the fields of {@code config}.
330 */
331 native long initializeConfiguration();
332
333 /**
334 * Resolves the implementation of {@code method} for virtual dispatches on objects of dynamic
335 * type {@code exactReceiver}. This resolution process only searches "up" the class hierarchy of
336 * {@code exactReceiver}.
337 *
338 * @param caller the caller or context type used to perform access checks
339 * @return the link-time resolved method (might be abstract) or {@code 0} if it can not be
340 * linked
341 */
342 native HotSpotResolvedJavaMethodImpl resolveMethod(HotSpotResolvedObjectTypeImpl exactReceiver, HotSpotResolvedJavaMethodImpl method, HotSpotResolvedObjectTypeImpl caller);
343
344 /**
345 * Gets the static initializer of {@code type}.
346 *
347 * @return 0 if {@code type} has no static initializer
348 */
349 native HotSpotResolvedJavaMethodImpl getClassInitializer(HotSpotResolvedObjectTypeImpl type);
350
351 /**
352 * Determines if {@code type} or any of its currently loaded subclasses overrides
353 * {@code Object.finalize()}.
354 */
355 native boolean hasFinalizableSubclass(HotSpotResolvedObjectTypeImpl type);
356
357 /**
358 * Gets the method corresponding to {@code holder} and slot number {@code slot} (i.e.
359 * {@link Method#slot} or {@link Constructor#slot}).
360 */
361 native HotSpotResolvedJavaMethodImpl getResolvedJavaMethodAtSlot(Class<?> holder, int slot);
362
363 /**
364 * Gets the maximum absolute offset of a PC relative call to {@code address} from any position
365 * in the code cache.
366 *
367 * @param address an address that may be called from any code in the code cache
368 * @return -1 if {@code address == 0}
369 */
370 public native long getMaxCallTargetOffset(long address);
371
372 /**
373 * Gets a textual disassembly of {@code codeBlob}.
374 *
375 * @return a non-zero length string containing a disassembly of {@code codeBlob} or null if
376 * {@code codeBlob} could not be disassembled for some reason
377 */
378 // The HotSpot disassembler seems not to be thread safe so it's better to synchronize its usage
379 public synchronized native String disassembleCodeBlob(long codeBlob);
380
381 /**
382 * Gets a stack trace element for {@code method} at bytecode index {@code bci}.
383 */
384 native StackTraceElement getStackTraceElement(HotSpotResolvedJavaMethodImpl method, int bci);
385
386 /**
387 * Executes some {@code installedCode} with arguments {@code args}.
388 *
389 * @return the result of executing {@code installedCode}
390 * @throws InvalidInstalledCodeException if {@code installedCode} has been invalidated
391 */
392 native Object executeInstalledCode(Object[] args, InstalledCode installedCode) throws InvalidInstalledCodeException;
393
394 /**
395 * Gets the line number table for {@code method}. The line number table is encoded as (bci,
396 * source line number) pairs.
397 *
398 * @return the line number table for {@code method} or null if it doesn't have one
399 */
400 native long[] getLineNumberTable(HotSpotResolvedJavaMethodImpl method);
401
402 /**
403 * Gets the number of entries in the local variable table for {@code method}.
404 *
405 * @return the number of entries in the local variable table for {@code method}
406 */
407 native int getLocalVariableTableLength(HotSpotResolvedJavaMethodImpl method);
408
409 /**
410 * Gets the address of the first entry in the local variable table for {@code method}.
411 *
412 * Each entry is a native object described by these fields:
413 *
414 * <ul>
415 * <li>{@link HotSpotVMConfig#localVariableTableElementSize}</li>
416 * <li>{@link HotSpotVMConfig#localVariableTableElementLengthOffset}</li>
417 * <li>{@link HotSpotVMConfig#localVariableTableElementNameCpIndexOffset}</li>
418 * <li>{@link HotSpotVMConfig#localVariableTableElementDescriptorCpIndexOffset}</li>
419 * <li>{@link HotSpotVMConfig#localVariableTableElementSignatureCpIndexOffset}
420 * <li>{@link HotSpotVMConfig#localVariableTableElementSlotOffset}
421 * <li>{@link HotSpotVMConfig#localVariableTableElementStartBciOffset}
422 * </ul>
423 *
424 * @return 0 if {@code method} does not have a local variable table
425 */
426 native long getLocalVariableTableStart(HotSpotResolvedJavaMethodImpl method);
427
428 /**
429 * Reads an object pointer within a VM data structure. That is, any {@link HotSpotVMField} whose
430 * {@link HotSpotVMField#type() type} is {@code "oop"} (e.g.,
431 * {@code ArrayKlass::_component_mirror}, {@code Klass::_java_mirror},
432 * {@code JavaThread::_threadObj}).
433 *
434 * Note that {@link Unsafe#getObject(Object, long)} cannot be used for this since it does a
435 * {@code narrowOop} read if the VM is using compressed oops whereas oops within VM data
436 * structures are (currently) always uncompressed.
437 *
438 * @param address address of an oop field within a VM data structure
439 */
440 native Object readUncompressedOop(long address);
441
442 /**
443 * Determines if {@code method} should not be inlined or compiled.
444 */
445 native void doNotInlineOrCompile(HotSpotResolvedJavaMethodImpl method);
446
447 /**
448 * Invalidates the profiling information for {@code method} and (re)initializes it such that
449 * profiling restarts upon its next invocation.
450 */
451 native void reprofile(HotSpotResolvedJavaMethodImpl method);
452
453 /**
454 * Invalidates {@code installedCode} such that {@link InvalidInstalledCodeException} will be
455 * raised the next time {@code installedCode} is executed.
456 */
457 public native void invalidateInstalledCode(InstalledCode installedCode);
458
459 /**
460 * Collects the current values of all JVMCI benchmark counters, summed up over all threads.
461 */
462 public native long[] collectCounters();
463
464 /**
465 * Determines if {@code metaspaceMethodData} is mature.
466 */
467 native boolean isMature(long metaspaceMethodData);
468
469 /**
470 * Generate a unique id to identify the result of the compile.
471 */
472 native int allocateCompileId(HotSpotResolvedJavaMethodImpl method, int entryBCI);
473
474 /**
475 * Determines if {@code method} has OSR compiled code identified by {@code entryBCI} for
476 * compilation level {@code level}.
477 */
478 native boolean hasCompiledCodeForOSR(HotSpotResolvedJavaMethodImpl method, int entryBCI, int level);
479
480 /**
481 * Gets the value of {@code metaspaceSymbol} as a String.
482 */
483 native String getSymbol(long metaspaceSymbol);
484
485 /**
486 * Looks for the next Java stack frame matching an entry in {@code methods}.
487 *
488 * @param frame the starting point of the search, where {@code null} refers to the topmost frame
489 * @param methods the methods to look for, where {@code null} means that any frame is returned
490 * @return the frame, or {@code null} if the end of the stack was reached during the search
491 */
492 public native HotSpotStackFrameReference getNextStackFrame(HotSpotStackFrameReference frame, HotSpotResolvedJavaMethodImpl[] methods, int initialSkip);
493
494 /**
495 * Materializes all virtual objects within {@code stackFrame} updates its locals.
496 *
497 * @param invalidate if {@code true}, the compiled method for the stack frame will be
498 * invalidated.
499 */
500 native void materializeVirtualObjects(HotSpotStackFrameReference stackFrame, boolean invalidate);
501
502 /**
503 * Gets the v-table index for interface method {@code method} in the receiver {@code type} or
504 * {@link HotSpotVMConfig#invalidVtableIndex} if {@code method} is not in {@code type}'s
505 * v-table.
506 *
507 * @throws InternalError if {@code type} is an interface or {@code method} is not held by an
508 * interface or class represented by {@code type} is not initialized
509 */
510 native int getVtableIndexForInterfaceMethod(HotSpotResolvedObjectTypeImpl type, HotSpotResolvedJavaMethodImpl method);
511
512 /**
513 * Determines if debug info should also be emitted at non-safepoint locations.
514 */
515 public native boolean shouldDebugNonSafepoints();
516
517 /**
518 * Writes {@code length} bytes from {@code bytes} starting at offset {@code offset} to the
519 * HotSpot's log stream.
520 *
521 * @exception NullPointerException if <code>bytes</code> is <code>null</code>.
522 * @exception IndexOutOfBoundsException if copying would cause access of data outside array
523 * bounds.
524 */
525 public native void writeDebugOutput(byte[] bytes, int offset, int length);
526
527 /**
528 * Flush HotSpot's log stream.
529 */
530 public native void flushDebugOutput();
531
532 /**
533 * Read a value representing a metaspace Method* and return the
534 * {@link HotSpotResolvedJavaMethodImpl} wrapping it. This method does no checking that the
535 * location actually contains a valid Method*. If the {@code base} object is a
536 * {@link HotSpotResolvedJavaMethodImpl}, {@link HotSpotConstantPool} or
537 * {@link HotSpotResolvedObjectTypeImpl} then the metaspace pointer is fetched from that object
538 * and used as the base. Otherwise the object itself is used as the base.
539 *
540 * @param base an object to read from or null
541 * @param displacement
542 * @return null or the resolved method for this location
543 */
544 native HotSpotResolvedJavaMethodImpl getResolvedJavaMethod(Object base, long displacement);
545
546 /**
547 * Read a value representing a metaspace ConstantPool* and return the
548 * {@link HotSpotConstantPool} wrapping it. This method does no checking that the location
549 * actually contains a valid ConstantPool*. If the {@code base} object is a
550 * {@link HotSpotResolvedJavaMethodImpl}, {@link HotSpotConstantPool} or
551 * {@link HotSpotResolvedObjectTypeImpl} then the metaspace pointer is fetched from that object
552 * and used as the base. Otherwise the object itself is used as the base.
553 *
554 * @param base an object to read from or null
555 * @param displacement
556 * @return null or the resolved method for this location
557 */
558 native HotSpotConstantPool getConstantPool(Object base, long displacement);
559
560 /**
561 * Read a value representing a metaspace Klass* and return the
562 * {@link HotSpotResolvedObjectTypeImpl} wrapping it. The method does no checking that the
563 * location actually contains a valid Klass*. If the {@code base} object is a
564 * {@link HotSpotResolvedJavaMethodImpl}, {@link HotSpotConstantPool} or
565 * {@link HotSpotResolvedObjectTypeImpl} then the metaspace pointer is fetched from that object
566 * and used as the base. Otherwise the object itself is used as the base.
567 *
568 * @param base an object to read from or null
569 * @param displacement
570 * @param compressed true if the location contains a compressed Klass*
571 * @return null or the resolved method for this location
572 */
573 native HotSpotResolvedObjectTypeImpl getResolvedJavaType(Object base, long displacement, boolean compressed);
574 }