1 /*
2 * Copyright (c) 2011, 2015, 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.hotspot.HotSpotJVMCIRuntime.runtime;
27 import static jdk.vm.ci.inittimer.InitTimer.timer;
28
29 import java.lang.reflect.Constructor;
30 import java.lang.reflect.Method;
31
32 import jdk.vm.ci.code.InstalledCode;
33 import jdk.vm.ci.code.InvalidInstalledCodeException;
34 import jdk.vm.ci.code.TargetDescription;
35 import jdk.vm.ci.common.JVMCIError;
36 import jdk.vm.ci.hotspotvmconfig.HotSpotVMField;
37 import jdk.vm.ci.inittimer.InitTimer;
38 import jdk.vm.ci.meta.JavaType;
39 import jdk.vm.ci.meta.ResolvedJavaMethod;
40 import jdk.vm.ci.meta.ResolvedJavaType;
41 import sun.misc.Unsafe;
42
43 /**
44 * Calls from Java into HotSpot. The behavior of all the methods in this class that take a native
45 * pointer as an argument (e.g., {@link #getSymbol(long)}) is undefined if the argument does not
46 * denote a valid native object.
47 */
48 final class CompilerToVM {
49 /**
50 * Initializes the native part of the JVMCI runtime.
51 */
52 private static native void registerNatives();
53
54 static {
55 initialize();
56 }
57
58 @SuppressWarnings("try")
59 private static void initialize() {
60 try (InitTimer t = timer("CompilerToVM.registerNatives")) {
61 registerNatives();
62 }
63 }
64
65 /**
66 * Gets the {@link CompilerToVM} instance associated with the singleton
67 * {@link HotSpotJVMCIRuntime} instance.
68 */
69 public static CompilerToVM compilerToVM() {
70 return runtime().getCompilerToVM();
71 }
72
73 /**
74 * Copies the original bytecode of {@code method} into a new byte array and returns it.
75 *
76 * @return a new byte array containing the original bytecode of {@code method}
77 */
78 native byte[] getBytecode(HotSpotResolvedJavaMethodImpl method);
79
80 /**
81 * Gets the number of entries in {@code method}'s exception handler table or 0 if it has not
82 * exception handler table.
83 */
84 native int getExceptionTableLength(HotSpotResolvedJavaMethodImpl method);
85
86 /**
87 * Gets the address of the first entry in {@code method}'s exception handler table.
88 *
89 * Each entry is a native object described by these fields:
90 *
91 * <ul>
92 * <li>{@link HotSpotVMConfig#exceptionTableElementSize}</li>
93 * <li>{@link HotSpotVMConfig#exceptionTableElementStartPcOffset}</li>
94 * <li>{@link HotSpotVMConfig#exceptionTableElementEndPcOffset}</li>
95 * <li>{@link HotSpotVMConfig#exceptionTableElementHandlerPcOffset}</li>
96 * <li>{@link HotSpotVMConfig#exceptionTableElementCatchTypeIndexOffset}
97 * </ul>
98 *
99 * @return 0 if {@code method} has no exception handlers (i.e.
100 * {@code getExceptionTableLength(method) == 0})
101 */
102 native long getExceptionTableStart(HotSpotResolvedJavaMethodImpl method);
103
104 /**
105 * Determines if {@code method} can be inlined. A method may not be inlinable for a number of
106 * reasons such as:
107 * <ul>
108 * <li>a CompileOracle directive may prevent inlining or compilation of methods</li>
109 * <li>the method may have a bytecode breakpoint set</li>
110 * <li>the method may have other bytecode features that require special handling by the VM</li>
111 * </ul>
112 */
113 native boolean canInlineMethod(HotSpotResolvedJavaMethodImpl method);
114
115 /**
116 * Determines if {@code method} should be inlined at any cost. This could be because:
117 * <ul>
118 * <li>a CompileOracle directive may forces inlining of this methods</li>
119 * <li>an annotation forces inlining of this method</li>
120 * </ul>
121 */
122 native boolean shouldInlineMethod(HotSpotResolvedJavaMethodImpl method);
123
124 /**
125 * Used to implement {@link ResolvedJavaType#findUniqueConcreteMethod(ResolvedJavaMethod)}.
126 *
127 * @param method the method on which to base the search
128 * @param actualHolderType the best known type of receiver
129 * @return the method result or 0 is there is no unique concrete method for {@code method}
130 */
131 native HotSpotResolvedJavaMethodImpl findUniqueConcreteMethod(HotSpotResolvedObjectTypeImpl actualHolderType, HotSpotResolvedJavaMethodImpl method);
132
133 /**
134 * Gets the implementor for the interface class {@code type}.
135 *
136 * @return the implementor if there is a single implementor, 0 if there is no implementor, or
137 * {@code type} itself if there is more than one implementor
138 */
139 native HotSpotResolvedObjectTypeImpl getImplementor(HotSpotResolvedObjectTypeImpl type);
140
141 /**
142 * Determines if {@code method} is ignored by security stack walks.
143 */
144 native boolean methodIsIgnoredBySecurityStackWalk(HotSpotResolvedJavaMethodImpl method);
145
146 /**
147 * Converts a name to a type.
148 *
149 * @param name a well formed Java type in {@linkplain JavaType#getName() internal} format
150 * @param accessingClass the context of resolution (must not be null)
151 * @param resolve force resolution to a {@link ResolvedJavaType}. If true, this method will
152 * either return a {@link ResolvedJavaType} or throw an exception
153 * @return the type for {@code name} or 0 if resolution failed and {@code resolve == false}
154 * @throws LinkageError if {@code resolve == true} and the resolution failed
155 */
156 native HotSpotResolvedObjectTypeImpl lookupType(String name, Class<?> accessingClass, boolean resolve);
157
158 /**
159 * Resolves the entry at index {@code cpi} in {@code constantPool} to an object.
160 *
161 * The behavior of this method is undefined if {@code cpi} does not denote one of the following
162 * entry types: {@code JVM_CONSTANT_MethodHandle}, {@code JVM_CONSTANT_MethodHandleInError},
163 * {@code JVM_CONSTANT_MethodType} and {@code JVM_CONSTANT_MethodTypeInError}.
164 */
165 native Object resolveConstantInPool(HotSpotConstantPool constantPool, int cpi);
166
167 /**
168 * Resolves the entry at index {@code cpi} in {@code constantPool} to an object, looking in the
169 * constant pool cache first.
170 *
171 * The behavior of this method is undefined if {@code cpi} does not denote a
172 * {@code JVM_CONSTANT_String} entry.
173 */
174 native Object resolvePossiblyCachedConstantInPool(HotSpotConstantPool constantPool, int cpi);
175
176 /**
177 * Gets the {@code JVM_CONSTANT_NameAndType} index from the entry at index {@code cpi} in
178 * {@code constantPool}.
179 *
180 * The behavior of this method is undefined if {@code cpi} does not denote an entry containing a
181 * {@code JVM_CONSTANT_NameAndType} index.
182 */
183 native int lookupNameAndTypeRefIndexInPool(HotSpotConstantPool constantPool, int cpi);
184
185 /**
186 * Gets the name 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 lookupNameInPool(HotSpotConstantPool constantPool, int which);
193
194 /**
195 * Gets the signature of the {@code JVM_CONSTANT_NameAndType} entry referenced by another entry
196 * denoted by {@code which} in {@code constantPool}.
197 *
198 * The behavior of this method is undefined if {@code which} does not denote a entry that
199 * references a {@code JVM_CONSTANT_NameAndType} entry.
200 */
201 native String lookupSignatureInPool(HotSpotConstantPool constantPool, int which);
202
203 /**
204 * Gets the {@code JVM_CONSTANT_Class} index from the entry at index {@code cpi} in
205 * {@code constantPool}.
206 *
207 * The behavior of this method is undefined if {@code cpi} does not denote an entry containing a
208 * {@code JVM_CONSTANT_Class} index.
209 */
210 native int lookupKlassRefIndexInPool(HotSpotConstantPool constantPool, int cpi);
211
212 /**
213 * Looks up a class denoted by the {@code JVM_CONSTANT_Class} entry at index {@code cpi} in
214 * {@code constantPool}. This method does not perform any resolution.
215 *
216 * The behavior of this method is undefined if {@code cpi} does not denote a
217 * {@code JVM_CONSTANT_Class} entry.
218 *
219 * @return the resolved class entry or a String otherwise
220 */
221 native Object lookupKlassInPool(HotSpotConstantPool constantPool, int cpi);
222
223 /**
224 * Looks up a method denoted by the entry at index {@code cpi} in {@code constantPool}. This
225 * method does not perform any resolution.
226 *
227 * The behavior of this method is undefined if {@code cpi} does not denote an entry representing
228 * a method.
229 *
230 * @param opcode the opcode of the instruction for which the lookup is being performed or
231 * {@code -1}. If non-negative, then resolution checks specific to the bytecode it
232 * denotes are performed if the method is already resolved. Should any of these
233 * checks fail, 0 is returned.
234 * @return the resolved method entry, 0 otherwise
235 */
236 native HotSpotResolvedJavaMethodImpl lookupMethodInPool(HotSpotConstantPool constantPool, int cpi, byte opcode);
237
238 /**
239 * Ensures that the type referenced by the specified {@code JVM_CONSTANT_InvokeDynamic} entry at
240 * index {@code cpi} in {@code constantPool} is loaded and initialized.
241 *
242 * The behavior of this method is undefined if {@code cpi} does not denote a
243 * {@code JVM_CONSTANT_InvokeDynamic} entry.
244 */
245 native void resolveInvokeDynamicInPool(HotSpotConstantPool constantPool, int cpi);
246
247 /**
248 * Ensures that the type referenced by the entry for a <a
249 * href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-2.html#jvms-2.9">signature
250 * polymorphic</a> method at index {@code cpi} in {@code constantPool} is loaded and
251 * initialized.
252 *
253 * The behavior of this method is undefined if {@code cpi} does not denote an entry representing
254 * a signature polymorphic method.
255 */
256 native void resolveInvokeHandleInPool(HotSpotConstantPool constantPool, int cpi);
257
258 /**
259 * Gets the resolved type denoted by the entry at index {@code cpi} in {@code constantPool}.
260 *
261 * The behavior of this method is undefined if {@code cpi} does not denote an entry representing
262 * a class.
263 *
264 * @throws LinkageError if resolution failed
265 */
266 native HotSpotResolvedObjectTypeImpl resolveTypeInPool(HotSpotConstantPool constantPool, int cpi) throws LinkageError;
267
268 /**
269 * Looks up and attempts to resolve the {@code JVM_CONSTANT_Field} entry at index {@code cpi} in
270 * {@code constantPool}. The values returned in {@code info} are:
271 *
272 * <pre>
273 * [(int) flags, // only valid if field is resolved
274 * (int) offset] // only valid if field is resolved
275 * </pre>
276 *
277 * The behavior of this method is undefined if {@code cpi} does not denote a
278 * {@code JVM_CONSTANT_Field} entry.
279 *
280 * @param info an array in which the details of the field are returned
281 * @return the type defining the field if resolution is successful, 0 otherwise
282 */
283 native HotSpotResolvedObjectTypeImpl resolveFieldInPool(HotSpotConstantPool constantPool, int cpi, byte opcode, long[] info);
284
285 /**
286 * Converts {@code cpci} from an index into the cache for {@code constantPool} to an index
287 * directly into {@code constantPool}.
288 *
289 * The behavior of this method is undefined if {@code ccpi} is an invalid constant pool cache
290 * index.
291 */
292 native int constantPoolRemapInstructionOperandFromCache(HotSpotConstantPool constantPool, int cpci);
293
294 /**
295 * Gets the appendix object (if any) associated with the entry at index {@code cpi} in
296 * {@code constantPool}.
297 */
298 native Object lookupAppendixInPool(HotSpotConstantPool constantPool, int cpi);
299
300 /**
301 * Installs the result of a compilation into the code cache.
302 *
303 * @param target the target where this code should be installed
304 * @param compiledCode the result of a compilation
305 * @param code the details of the installed CodeBlob are written to this object
306 * @return the outcome of the installation which will be one of
307 * {@link HotSpotVMConfig#codeInstallResultOk},
308 * {@link HotSpotVMConfig#codeInstallResultCacheFull},
309 * {@link HotSpotVMConfig#codeInstallResultCodeTooLarge},
310 * {@link HotSpotVMConfig#codeInstallResultDependenciesFailed} or
311 * {@link HotSpotVMConfig#codeInstallResultDependenciesInvalid}.
312 * @throws JVMCIError if there is something wrong with the compiled code or the associated
313 * metadata.
314 */
315 native int installCode(TargetDescription target, HotSpotCompiledCode compiledCode, InstalledCode code, HotSpotSpeculationLog speculationLog);
316
317 public native int getMetadata(TargetDescription target, HotSpotCompiledCode compiledCode, HotSpotMetaData metaData);
318
319 /**
320 * Notifies the VM of statistics for a completed compilation.
321 *
322 * @param id the identifier of the compilation
323 * @param method the method compiled
324 * @param osr specifies if the compilation was for on-stack-replacement
325 * @param processedBytecodes the number of bytecodes processed during the compilation, including
326 * the bytecodes of all inlined methods
327 * @param time the amount time spent compiling {@code method}
328 * @param timeUnitsPerSecond the granularity of the units for the {@code time} value
329 * @param installedCode the nmethod installed as a result of the compilation
330 */
331 synchronized native void notifyCompilationStatistics(int id, HotSpotResolvedJavaMethodImpl method, boolean osr, int processedBytecodes, long time, long timeUnitsPerSecond,
332 InstalledCode installedCode);
333
334 /**
335 * Resets all compilation statistics.
336 */
337 native void resetCompilationStatistics();
338
339 /**
340 * Initializes the fields of {@code config}.
341 */
342 native long initializeConfiguration(HotSpotVMConfig config);
343
344 /**
345 * Resolves the implementation of {@code method} for virtual dispatches on objects of dynamic
346 * type {@code exactReceiver}. This resolution process only searches "up" the class hierarchy of
347 * {@code exactReceiver}.
348 *
349 * @param caller the caller or context type used to perform access checks
350 * @return the link-time resolved method (might be abstract) or {@code 0} if it can not be
351 * linked
352 */
353 native HotSpotResolvedJavaMethodImpl resolveMethod(HotSpotResolvedObjectTypeImpl exactReceiver, HotSpotResolvedJavaMethodImpl method, HotSpotResolvedObjectTypeImpl caller);
354
355 /**
356 * Gets the static initializer of {@code type}.
357 *
358 * @return 0 if {@code type} has no static initializer
359 */
360 native HotSpotResolvedJavaMethodImpl getClassInitializer(HotSpotResolvedObjectTypeImpl type);
361
362 /**
363 * Determines if {@code type} or any of its currently loaded subclasses overrides
364 * {@code Object.finalize()}.
365 */
366 native boolean hasFinalizableSubclass(HotSpotResolvedObjectTypeImpl type);
367
368 /**
369 * Gets the method corresponding to {@code holder} and slot number {@code slot} (i.e.
370 * {@link Method#slot} or {@link Constructor#slot}).
371 */
372 native HotSpotResolvedJavaMethodImpl getResolvedJavaMethodAtSlot(Class<?> holder, int slot);
373
374 /**
375 * Gets the maximum absolute offset of a PC relative call to {@code address} from any position
376 * in the code cache.
377 *
378 * @param address an address that may be called from any code in the code cache
379 * @return -1 if {@code address == 0}
380 */
381 native long getMaxCallTargetOffset(long address);
382
383 /**
384 * Gets a textual disassembly of {@code codeBlob}.
385 *
386 * @return a non-zero length string containing a disassembly of {@code codeBlob} or null if
387 * {@code codeBlob} could not be disassembled for some reason
388 */
389 // The HotSpot disassembler seems not to be thread safe so it's better to synchronize its usage
390 synchronized native String disassembleCodeBlob(InstalledCode installedCode);
391
392 /**
393 * Gets a stack trace element for {@code method} at bytecode index {@code bci}.
394 */
395 native StackTraceElement getStackTraceElement(HotSpotResolvedJavaMethodImpl method, int bci);
396
397 /**
398 * Executes some {@code installedCode} with arguments {@code args}.
399 *
400 * @return the result of executing {@code installedCode}
401 * @throws InvalidInstalledCodeException if {@code installedCode} has been invalidated
402 */
403 native Object executeInstalledCode(Object[] args, InstalledCode installedCode) throws InvalidInstalledCodeException;
404
405 /**
406 * Gets the line number table for {@code method}. The line number table is encoded as (bci,
407 * source line number) pairs.
408 *
409 * @return the line number table for {@code method} or null if it doesn't have one
410 */
411 native long[] getLineNumberTable(HotSpotResolvedJavaMethodImpl method);
412
413 /**
414 * Gets the number of entries in the local variable table for {@code method}.
415 *
416 * @return the number of entries in the local variable table for {@code method}
417 */
418 native int getLocalVariableTableLength(HotSpotResolvedJavaMethodImpl method);
419
420 /**
421 * Gets the address of the first entry in the local variable table for {@code method}.
422 *
423 * Each entry is a native object described by these fields:
424 *
425 * <ul>
426 * <li>{@link HotSpotVMConfig#localVariableTableElementSize}</li>
427 * <li>{@link HotSpotVMConfig#localVariableTableElementLengthOffset}</li>
428 * <li>{@link HotSpotVMConfig#localVariableTableElementNameCpIndexOffset}</li>
429 * <li>{@link HotSpotVMConfig#localVariableTableElementDescriptorCpIndexOffset}</li>
430 * <li>{@link HotSpotVMConfig#localVariableTableElementSignatureCpIndexOffset}
431 * <li>{@link HotSpotVMConfig#localVariableTableElementSlotOffset}
432 * <li>{@link HotSpotVMConfig#localVariableTableElementStartBciOffset}
433 * </ul>
434 *
435 * @return 0 if {@code method} does not have a local variable table
436 */
437 native long getLocalVariableTableStart(HotSpotResolvedJavaMethodImpl method);
438
439 /**
440 * Reads an object pointer within a VM data structure. That is, any {@link HotSpotVMField} whose
441 * {@link HotSpotVMField#type() type} is {@code "oop"} (e.g.,
442 * {@code ArrayKlass::_component_mirror}, {@code Klass::_java_mirror},
443 * {@code JavaThread::_threadObj}).
444 *
445 * Note that {@link Unsafe#getObject(Object, long)} cannot be used for this since it does a
446 * {@code narrowOop} read if the VM is using compressed oops whereas oops within VM data
447 * structures are (currently) always uncompressed.
448 *
449 * @param address address of an oop field within a VM data structure
450 */
451 native Object readUncompressedOop(long address);
452
453 /**
454 * Determines if {@code method} should not be inlined or compiled.
455 */
456 native void doNotInlineOrCompile(HotSpotResolvedJavaMethodImpl method);
457
458 /**
459 * Invalidates the profiling information for {@code method} and (re)initializes it such that
460 * profiling restarts upon its next invocation.
461 */
462 native void reprofile(HotSpotResolvedJavaMethodImpl method);
463
464 /**
465 * Invalidates {@code installedCode} such that {@link InvalidInstalledCodeException} will be
466 * raised the next time {@code installedCode} is executed.
467 */
468 native void invalidateInstalledCode(InstalledCode installedCode);
469
470 /**
471 * Collects the current values of all JVMCI benchmark counters, summed up over all threads.
472 */
473 native long[] collectCounters();
474
475 /**
476 * Determines if {@code metaspaceMethodData} is mature.
477 */
478 native boolean isMature(long metaspaceMethodData);
479
480 /**
481 * Generate a unique id to identify the result of the compile.
482 */
483 native int allocateCompileId(HotSpotResolvedJavaMethodImpl method, int entryBCI);
484
485 /**
486 * Determines if {@code method} has OSR compiled code identified by {@code entryBCI} for
487 * compilation level {@code level}.
488 */
489 native boolean hasCompiledCodeForOSR(HotSpotResolvedJavaMethodImpl method, int entryBCI, int level);
490
491 /**
492 * Gets the value of {@code metaspaceSymbol} as a String.
493 */
494 native String getSymbol(long metaspaceSymbol);
495
496 /**
497 * Looks for the next Java stack frame matching an entry in {@code methods}.
498 *
499 * @param frame the starting point of the search, where {@code null} refers to the topmost frame
500 * @param methods the methods to look for, where {@code null} means that any frame is returned
501 * @return the frame, or {@code null} if the end of the stack was reached during the search
502 */
503 native HotSpotStackFrameReference getNextStackFrame(HotSpotStackFrameReference frame, ResolvedJavaMethod[] methods, int initialSkip);
504
505 /**
506 * Materializes all virtual objects within {@code stackFrame} updates its locals.
507 *
508 * @param invalidate if {@code true}, the compiled method for the stack frame will be
509 * invalidated.
510 */
511 native void materializeVirtualObjects(HotSpotStackFrameReference stackFrame, boolean invalidate);
512
513 /**
514 * Gets the v-table index for interface method {@code method} in the receiver {@code type} or
515 * {@link HotSpotVMConfig#invalidVtableIndex} if {@code method} is not in {@code type}'s
516 * v-table.
517 *
518 * @throws InternalError if {@code type} is an interface or {@code method} is not held by an
519 * interface or class represented by {@code type} is not initialized
520 */
521 native int getVtableIndexForInterfaceMethod(HotSpotResolvedObjectTypeImpl type, HotSpotResolvedJavaMethodImpl method);
522
523 /**
524 * Determines if debug info should also be emitted at non-safepoint locations.
525 */
526
527 native boolean shouldDebugNonSafepoints();
528
529 /**
530 * Writes {@code length} bytes from {@code bytes} starting at offset {@code offset} to the
531 * HotSpot's log stream.
532 *
533 * @exception NullPointerException if {@code bytes == null}
534 * @exception IndexOutOfBoundsException if copying would cause access of data outside array
535 * bounds
536 */
537 native void writeDebugOutput(byte[] bytes, int offset, int length);
538
539 /**
540 * Flush HotSpot's log stream.
541 */
542 native void flushDebugOutput();
543
544 /**
545 * Read a HotSpot Method* value from the memory location described by {@code base} plus
546 * {@code displacement} and return the {@link HotSpotResolvedJavaMethodImpl} wrapping it. This
547 * method does no checking that the memory location actually contains a valid pointer and may
548 * crash the VM if an invalid location is provided. If the {@code base} is null then
549 * {@code displacement} is used by itself. If {@code base} is a
550 * {@link HotSpotResolvedJavaMethodImpl}, {@link HotSpotConstantPool} or
551 * {@link HotSpotResolvedObjectTypeImpl} then the metaspace pointer is fetched from that object
552 * and added to {@code displacement}. Any other non-null object type causes an
553 * {@link IllegalArgumentException} to be thrown.
554 *
555 * @param base an object to read from or null
556 * @param displacement
557 * @return null or the resolved method for this location
558 */
559 native HotSpotResolvedJavaMethodImpl getResolvedJavaMethod(Object base, long displacement);
560
561 /**
562 * Read a HotSpot ConstantPool* value from the memory location described by {@code base} plus
563 * {@code displacement} and return the {@link HotSpotConstantPool} wrapping it. This method does
564 * no checking that the memory location actually contains a valid pointer and may crash the VM
565 * if an invalid location is provided. If the {@code base} is null then {@code displacement} is
566 * used by itself. If {@code base} is a {@link HotSpotResolvedJavaMethodImpl},
567 * {@link HotSpotConstantPool} or {@link HotSpotResolvedObjectTypeImpl} then the metaspace
568 * pointer is fetched from that object and added to {@code displacement}. Any other non-null
569 * object type causes an {@link IllegalArgumentException} to be thrown.
570 *
571 * @param base an object to read from or null
572 * @param displacement
573 * @return null or the resolved method for this location
574 */
575 native HotSpotConstantPool getConstantPool(Object base, long displacement);
576
577 /**
578 * Read a HotSpot Klass* value from the memory location described by {@code base} plus
579 * {@code displacement} and return the {@link HotSpotResolvedObjectTypeImpl} wrapping it. This
580 * method does no checking that the memory location actually contains a valid pointer and may
581 * crash the VM if an invalid location is provided. If the {@code base} is null then
582 * {@code displacement} is used by itself. If {@code base} is a
583 * {@link HotSpotResolvedJavaMethodImpl}, {@link HotSpotConstantPool} or
584 * {@link HotSpotResolvedObjectTypeImpl} then the metaspace pointer is fetched from that object
585 * and added to {@code displacement}. Any other non-null object type causes an
586 * {@link IllegalArgumentException} to be thrown.
587 *
588 * @param base an object to read from or null
589 * @param displacement
590 * @param compressed true if the location contains a compressed Klass*
591 * @return null or the resolved method for this location
592 */
593 native HotSpotResolvedObjectTypeImpl getResolvedJavaType(Object base, long displacement, boolean compressed);
594
595 /**
596 * Return the size of the HotSpot ProfileData* pointed at by {@code position}. If
597 * {@code position} is outside the space of the MethodData then an
598 * {@link IllegalArgumentException} is thrown. A {@code position} inside the MethodData but that
599 * isn't pointing at a valid ProfileData will crash the VM.
600 *
601 * @param metaspaceMethodData
602 * @param position
603 * @return the size of the ProfileData item pointed at by {@code position}
604 * @throws IllegalArgumentException if an out of range position is given
605 */
606 native int methodDataProfileDataSize(long metaspaceMethodData, int position);
607 }