1 /*
2 * Copyright (c) 2000, 2016, 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 package jdk.internal.misc;
27
28 import java.lang.reflect.Field;
29 import java.security.ProtectionDomain;
30
31 import jdk.internal.vm.annotation.ForceInline;
32 import sun.reflect.CallerSensitive;
33 import sun.reflect.Reflection;
34 import jdk.internal.misc.VM;
35
36 import jdk.internal.HotSpotIntrinsicCandidate;
37
38
39 /**
40 * A collection of methods for performing low-level, unsafe operations.
41 * Although the class and all methods are public, use of this class is
42 * limited because only trusted code can obtain instances of it.
43 *
44 * <em>Note:</em> It is the resposibility of the caller to make sure
45 * arguments are checked before methods of this class are
46 * called. While some rudimentary checks are performed on the input,
47 * the checks are best effort and when performance is an overriding
48 * priority, as when methods of this class are optimized by the
49 * runtime compiler, some or all checks (if any) may be elided. Hence,
50 * the caller must not rely on the checks and corresponding
51 * exceptions!
52 *
53 * @author John R. Rose
54 * @see #getUnsafe
55 */
56
57 public final class Unsafe {
58
59 private static native void registerNatives();
60 static {
61 registerNatives();
62 sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe");
63 }
64
65 private Unsafe() {}
66
67 private static final Unsafe theUnsafe = new Unsafe();
68
69 /**
70 * Provides the caller with the capability of performing unsafe
71 * operations.
72 *
73 * <p>The returned {@code Unsafe} object should be carefully guarded
74 * by the caller, since it can be used to read and write data at arbitrary
75 * memory addresses. It must never be passed to untrusted code.
76 *
77 * <p>Most methods in this class are very low-level, and correspond to a
78 * small number of hardware instructions (on typical machines). Compilers
79 * are encouraged to optimize these methods accordingly.
80 *
81 * <p>Here is a suggested idiom for using unsafe operations:
82 *
83 * <pre> {@code
84 * class MyTrustedClass {
85 * private static final Unsafe unsafe = Unsafe.getUnsafe();
86 * ...
87 * private long myCountAddress = ...;
88 * public int getCount() { return unsafe.getByte(myCountAddress); }
89 * }}</pre>
90 *
91 * (It may assist compilers to make the local variable {@code final}.)
92 *
93 * @throws SecurityException if a security manager exists and its
94 * {@code checkPropertiesAccess} method doesn't allow
95 * access to the system properties.
96 */
97 @CallerSensitive
98 public static Unsafe getUnsafe() {
99 Class<?> caller = Reflection.getCallerClass();
100 if (!VM.isSystemDomainLoader(caller.getClassLoader()))
101 throw new SecurityException("Unsafe");
102 return theUnsafe;
103 }
104
105 /// peek and poke operations
106 /// (compilers should optimize these to memory ops)
107
108 // These work on object fields in the Java heap.
109 // They will not work on elements of packed arrays.
110
111 /**
112 * Fetches a value from a given Java variable.
113 * More specifically, fetches a field or array element within the given
114 * object {@code o} at the given offset, or (if {@code o} is null)
115 * from the memory address whose numerical value is the given offset.
116 * <p>
117 * The results are undefined unless one of the following cases is true:
118 * <ul>
119 * <li>The offset was obtained from {@link #objectFieldOffset} on
120 * the {@link java.lang.reflect.Field} of some Java field and the object
121 * referred to by {@code o} is of a class compatible with that
122 * field's class.
123 *
124 * <li>The offset and object reference {@code o} (either null or
125 * non-null) were both obtained via {@link #staticFieldOffset}
126 * and {@link #staticFieldBase} (respectively) from the
127 * reflective {@link Field} representation of some Java field.
128 *
129 * <li>The object referred to by {@code o} is an array, and the offset
130 * is an integer of the form {@code B+N*S}, where {@code N} is
131 * a valid index into the array, and {@code B} and {@code S} are
132 * the values obtained by {@link #arrayBaseOffset} and {@link
133 * #arrayIndexScale} (respectively) from the array's class. The value
134 * referred to is the {@code N}<em>th</em> element of the array.
135 *
136 * </ul>
137 * <p>
138 * If one of the above cases is true, the call references a specific Java
139 * variable (field or array element). However, the results are undefined
140 * if that variable is not in fact of the type returned by this method.
141 * <p>
142 * This method refers to a variable by means of two parameters, and so
143 * it provides (in effect) a <em>double-register</em> addressing mode
144 * for Java variables. When the object reference is null, this method
145 * uses its offset as an absolute address. This is similar in operation
146 * to methods such as {@link #getInt(long)}, which provide (in effect) a
147 * <em>single-register</em> addressing mode for non-Java variables.
148 * However, because Java variables may have a different layout in memory
149 * from non-Java variables, programmers should not assume that these
150 * two addressing modes are ever equivalent. Also, programmers should
151 * remember that offsets from the double-register addressing mode cannot
152 * be portably confused with longs used in the single-register addressing
153 * mode.
154 *
155 * @param o Java heap object in which the variable resides, if any, else
156 * null
157 * @param offset indication of where the variable resides in a Java heap
158 * object, if any, else a memory address locating the variable
159 * statically
160 * @return the value fetched from the indicated Java variable
161 * @throws RuntimeException No defined exceptions are thrown, not even
162 * {@link NullPointerException}
163 */
164 @HotSpotIntrinsicCandidate
165 public native int getInt(Object o, long offset);
166
167 /**
168 * Stores a value into a given Java variable.
169 * <p>
170 * The first two parameters are interpreted exactly as with
171 * {@link #getInt(Object, long)} to refer to a specific
172 * Java variable (field or array element). The given value
173 * is stored into that variable.
174 * <p>
175 * The variable must be of the same type as the method
176 * parameter {@code x}.
177 *
178 * @param o Java heap object in which the variable resides, if any, else
179 * null
180 * @param offset indication of where the variable resides in a Java heap
181 * object, if any, else a memory address locating the variable
182 * statically
183 * @param x the value to store into the indicated Java variable
184 * @throws RuntimeException No defined exceptions are thrown, not even
185 * {@link NullPointerException}
186 */
187 @HotSpotIntrinsicCandidate
188 public native void putInt(Object o, long offset, int x);
189
190 /**
191 * Fetches a reference value from a given Java variable.
192 * @see #getInt(Object, long)
193 */
194 @HotSpotIntrinsicCandidate
195 public native Object getObject(Object o, long offset);
196
197 /**
198 * Stores a reference value into a given Java variable.
199 * <p>
200 * Unless the reference {@code x} being stored is either null
201 * or matches the field type, the results are undefined.
202 * If the reference {@code o} is non-null, card marks or
203 * other store barriers for that object (if the VM requires them)
204 * are updated.
205 * @see #putInt(Object, long, int)
206 */
207 @HotSpotIntrinsicCandidate
208 public native void putObject(Object o, long offset, Object x);
209
210 /** @see #getInt(Object, long) */
211 @HotSpotIntrinsicCandidate
212 public native boolean getBoolean(Object o, long offset);
213 /** @see #putInt(Object, long, int) */
214 @HotSpotIntrinsicCandidate
215 public native void putBoolean(Object o, long offset, boolean x);
216 /** @see #getInt(Object, long) */
217 @HotSpotIntrinsicCandidate
218 public native byte getByte(Object o, long offset);
219 /** @see #putInt(Object, long, int) */
220 @HotSpotIntrinsicCandidate
221 public native void putByte(Object o, long offset, byte x);
222 /** @see #getInt(Object, long) */
223 @HotSpotIntrinsicCandidate
224 public native short getShort(Object o, long offset);
225 /** @see #putInt(Object, long, int) */
226 @HotSpotIntrinsicCandidate
227 public native void putShort(Object o, long offset, short x);
228 /** @see #getInt(Object, long) */
229 @HotSpotIntrinsicCandidate
230 public native char getChar(Object o, long offset);
231 /** @see #putInt(Object, long, int) */
232 @HotSpotIntrinsicCandidate
233 public native void putChar(Object o, long offset, char x);
234 /** @see #getInt(Object, long) */
235 @HotSpotIntrinsicCandidate
236 public native long getLong(Object o, long offset);
237 /** @see #putInt(Object, long, int) */
238 @HotSpotIntrinsicCandidate
239 public native void putLong(Object o, long offset, long x);
240 /** @see #getInt(Object, long) */
241 @HotSpotIntrinsicCandidate
242 public native float getFloat(Object o, long offset);
243 /** @see #putInt(Object, long, int) */
244 @HotSpotIntrinsicCandidate
245 public native void putFloat(Object o, long offset, float x);
246 /** @see #getInt(Object, long) */
247 @HotSpotIntrinsicCandidate
248 public native double getDouble(Object o, long offset);
249 /** @see #putInt(Object, long, int) */
250 @HotSpotIntrinsicCandidate
251 public native void putDouble(Object o, long offset, double x);
252
253 // These read VM internal data.
254
255 /**
256 * Fetches an uncompressed reference value from a given native variable
257 * ignoring the VM's compressed references mode.
258 *
259 * @param address a memory address locating the variable
260 * @return the value fetched from the indicated native variable
261 */
262 public native Object getUncompressedObject(long address);
263
264 /**
265 * Fetches the {@link java.lang.Class} Java mirror for the given native
266 * metaspace {@code Klass} pointer.
267 *
268 * @param metaspaceKlass a native metaspace {@code Klass} pointer
269 * @return the {@link java.lang.Class} Java mirror
270 */
271 public native Class<?> getJavaMirror(long metaspaceKlass);
272
273 /**
274 * Fetches a native metaspace {@code Klass} pointer for the given Java
275 * object.
276 *
277 * @param o Java heap object for which to fetch the class pointer
278 * @return a native metaspace {@code Klass} pointer
279 */
280 public native long getKlassPointer(Object o);
281
282 // These work on values in the C heap.
283
284 /**
285 * Fetches a value from a given memory address. If the address is zero, or
286 * does not point into a block obtained from {@link #allocateMemory}, the
287 * results are undefined.
288 *
289 * @see #allocateMemory
290 */
291 @HotSpotIntrinsicCandidate
292 public native byte getByte(long address);
293
294 /**
295 * Stores a value into a given memory address. If the address is zero, or
296 * does not point into a block obtained from {@link #allocateMemory}, the
297 * results are undefined.
298 *
299 * @see #getByte(long)
300 */
301 @HotSpotIntrinsicCandidate
302 public native void putByte(long address, byte x);
303
304 /** @see #getByte(long) */
305 @HotSpotIntrinsicCandidate
306 public native short getShort(long address);
307 /** @see #putByte(long, byte) */
308 @HotSpotIntrinsicCandidate
309 public native void putShort(long address, short x);
310 /** @see #getByte(long) */
311 @HotSpotIntrinsicCandidate
312 public native char getChar(long address);
313 /** @see #putByte(long, byte) */
314 @HotSpotIntrinsicCandidate
315 public native void putChar(long address, char x);
316 /** @see #getByte(long) */
317 @HotSpotIntrinsicCandidate
318 public native int getInt(long address);
319 /** @see #putByte(long, byte) */
320 @HotSpotIntrinsicCandidate
321 public native void putInt(long address, int x);
322 /** @see #getByte(long) */
323 @HotSpotIntrinsicCandidate
324 public native long getLong(long address);
325 /** @see #putByte(long, byte) */
326 @HotSpotIntrinsicCandidate
327 public native void putLong(long address, long x);
328 /** @see #getByte(long) */
329 @HotSpotIntrinsicCandidate
330 public native float getFloat(long address);
331 /** @see #putByte(long, byte) */
332 @HotSpotIntrinsicCandidate
333 public native void putFloat(long address, float x);
334 /** @see #getByte(long) */
335 @HotSpotIntrinsicCandidate
336 public native double getDouble(long address);
337 /** @see #putByte(long, byte) */
338 @HotSpotIntrinsicCandidate
339 public native void putDouble(long address, double x);
340
341 /**
342 * Fetches a native pointer from a given memory address. If the address is
343 * zero, or does not point into a block obtained from {@link
344 * #allocateMemory}, the results are undefined.
345 *
346 * <p>If the native pointer is less than 64 bits wide, it is extended as
347 * an unsigned number to a Java long. The pointer may be indexed by any
348 * given byte offset, simply by adding that offset (as a simple integer) to
349 * the long representing the pointer. The number of bytes actually read
350 * from the target address may be determined by consulting {@link
351 * #addressSize}.
352 *
353 * @see #allocateMemory
354 */
355 @HotSpotIntrinsicCandidate
356 public native long getAddress(long address);
357
358 /**
359 * Stores a native pointer into a given memory address. If the address is
360 * zero, or does not point into a block obtained from {@link
361 * #allocateMemory}, the results are undefined.
362 *
363 * <p>The number of bytes actually written at the target address may be
364 * determined by consulting {@link #addressSize}.
365 *
366 * @see #getAddress(long)
367 */
368 @HotSpotIntrinsicCandidate
369 public native void putAddress(long address, long x);
370
371
372
373 /// helper methods for validating various types of objects/values
374
375 /**
376 * Create an exception reflecting that some of the input was invalid
377 *
378 * <em>Note:</em> It is the resposibility of the caller to make
379 * sure arguments are checked before the methods are called. While
380 * some rudimentary checks are performed on the input, the checks
381 * are best effort and when performance is an overriding priority,
382 * as when methods of this class are optimized by the runtime
383 * compiler, some or all checks (if any) may be elided. Hence, the
384 * caller must not rely on the checks and corresponding
385 * exceptions!
386 *
387 * @return an exception object
388 */
389 private RuntimeException invalidInput() {
390 return new IllegalArgumentException();
391 }
392
393 /**
394 * Check if a value is 32-bit clean (32 MSB are all zero)
395 *
396 * @param value the 64-bit value to check
397 *
398 * @return true if the value is 32-bit clean
399 */
400 private boolean is32BitClean(long value) {
401 return value >>> 32 == 0;
402 }
403
404 /**
405 * Check the validity of a size (the equivalent of a size_t)
406 *
407 * @throws RuntimeException if the size is invalid
408 * (<em>Note:</em> after optimization, invalid inputs may
409 * go undetected, which will lead to unpredictable
410 * behavior)
411 */
412 private void checkSize(long size) {
413 if (ADDRESS_SIZE == 4) {
414 // Note: this will also check for negative sizes
415 if (!is32BitClean(size)) {
416 throw invalidInput();
417 }
418 } else if (size < 0) {
419 throw invalidInput();
420 }
421 }
422
423 /**
424 * Check the validity of a native address (the equivalent of void*)
425 *
426 * @throws RuntimeException if the address is invalid
427 * (<em>Note:</em> after optimization, invalid inputs may
428 * go undetected, which will lead to unpredictable
429 * behavior)
430 */
431 private void checkNativeAddress(long address) {
432 if (ADDRESS_SIZE == 4) {
433 // Accept both zero and sign extended pointers. A valid
434 // pointer will, after the +1 below, either have produced
435 // the value 0x0 or 0x1. Masking off the low bit allows
436 // for testing against 0.
437 if ((((address >> 32) + 1) & ~1) != 0) {
438 throw invalidInput();
439 }
440 }
441 }
442
443 /**
444 * Check the validity of an offset, relative to a base object
445 *
446 * @param o the base object
447 * @param offset the offset to check
448 *
449 * @throws RuntimeException if the size is invalid
450 * (<em>Note:</em> after optimization, invalid inputs may
451 * go undetected, which will lead to unpredictable
452 * behavior)
453 */
454 private void checkOffset(Object o, long offset) {
455 if (ADDRESS_SIZE == 4) {
456 // Note: this will also check for negative offsets
457 if (!is32BitClean(offset)) {
458 throw invalidInput();
459 }
460 } else if (offset < 0) {
461 throw invalidInput();
462 }
463 }
464
465 /**
466 * Check the validity of a double-register pointer
467 *
468 * Note: This code deliberately does *not* check for NPE for (at
469 * least) three reasons:
470 *
471 * 1) NPE is not just NULL/0 - there is a range of values all
472 * resulting in an NPE, which is not trivial to check for
473 *
474 * 2) It is the responsibility of the callers of Unsafe methods
475 * to verify the input, so throwing an exception here is not really
476 * useful - passing in a NULL pointer is a critical error and the
477 * must not expect an exception to be thrown anyway.
478 *
479 * 3) the actual operations will detect NULL pointers anyway by
480 * means of traps and signals (like SIGSEGV).
481 *
482 * @param o Java heap object, or null
483 * @param offset indication of where the variable resides in a Java heap
484 * object, if any, else a memory address locating the variable
485 * statically
486 *
487 * @throws RuntimeException if the pointer is invalid
488 * (<em>Note:</em> after optimization, invalid inputs may
489 * go undetected, which will lead to unpredictable
490 * behavior)
491 */
492 private void checkPointer(Object o, long offset) {
493 if (o == null) {
494 checkNativeAddress(offset);
495 } else {
496 checkOffset(o, offset);
497 }
498 }
499
500 /**
501 * Check if a type is a primitive array type
502 *
503 * @param c the type to check
504 *
505 * @return true if the type is a primitive array type
506 */
507 private void checkPrimitiveArray(Class<?> c) {
508 Class<?> componentType = c.getComponentType();
509 if (componentType == null || !componentType.isPrimitive()) {
510 throw invalidInput();
511 }
512 }
513
514 /**
515 * Check that a pointer is a valid primitive array type pointer
516 *
517 * Note: pointers off-heap are considered to be primitive arrays
518 *
519 * @throws RuntimeException if the pointer is invalid
520 * (<em>Note:</em> after optimization, invalid inputs may
521 * go undetected, which will lead to unpredictable
522 * behavior)
523 */
524 private void checkPrimitivePointer(Object o, long offset) {
525 checkPointer(o, offset);
526
527 if (o != null) {
528 // If on heap, it it must be a primitive array
529 checkPrimitiveArray(o.getClass());
530 }
531 }
532
533
534 /// wrappers for malloc, realloc, free:
535
536 /**
537 * Allocates a new block of native memory, of the given size in bytes. The
538 * contents of the memory are uninitialized; they will generally be
539 * garbage. The resulting native pointer will never be zero, and will be
540 * aligned for all value types. Dispose of this memory by calling {@link
541 * #freeMemory}, or resize it with {@link #reallocateMemory}.
542 *
543 * <em>Note:</em> It is the resposibility of the caller to make
544 * sure arguments are checked before the methods are called. While
545 * some rudimentary checks are performed on the input, the checks
546 * are best effort and when performance is an overriding priority,
547 * as when methods of this class are optimized by the runtime
548 * compiler, some or all checks (if any) may be elided. Hence, the
549 * caller must not rely on the checks and corresponding
550 * exceptions!
551 *
552 * @throws RuntimeException if the size is negative or too large
553 * for the native size_t type
554 *
555 * @throws OutOfMemoryError if the allocation is refused by the system
556 *
557 * @see #getByte(long)
558 * @see #putByte(long, byte)
559 */
560 public long allocateMemory(long bytes) {
561 allocateMemoryChecks(bytes);
562
563 if (bytes == 0) {
564 return 0;
565 }
566
567 long p = allocateMemory0(bytes);
568 if (p == 0) {
569 throw new OutOfMemoryError();
570 }
571
572 return p;
573 }
574
575 /**
576 * Validate the arguments to allocateMemory
577 *
578 * @throws RuntimeException if the arguments are invalid
579 * (<em>Note:</em> after optimization, invalid inputs may
580 * go undetected, which will lead to unpredictable
581 * behavior)
582 */
583 private void allocateMemoryChecks(long bytes) {
584 checkSize(bytes);
585 }
586
587 /**
588 * Resizes a new block of native memory, to the given size in bytes. The
589 * contents of the new block past the size of the old block are
590 * uninitialized; they will generally be garbage. The resulting native
591 * pointer will be zero if and only if the requested size is zero. The
592 * resulting native pointer will be aligned for all value types. Dispose
593 * of this memory by calling {@link #freeMemory}, or resize it with {@link
594 * #reallocateMemory}. The address passed to this method may be null, in
595 * which case an allocation will be performed.
596 *
597 * <em>Note:</em> It is the resposibility of the caller to make
598 * sure arguments are checked before the methods are called. While
599 * some rudimentary checks are performed on the input, the checks
600 * are best effort and when performance is an overriding priority,
601 * as when methods of this class are optimized by the runtime
602 * compiler, some or all checks (if any) may be elided. Hence, the
603 * caller must not rely on the checks and corresponding
604 * exceptions!
605 *
606 * @throws RuntimeException if the size is negative or too large
607 * for the native size_t type
608 *
609 * @throws OutOfMemoryError if the allocation is refused by the system
610 *
611 * @see #allocateMemory
612 */
613 public long reallocateMemory(long address, long bytes) {
614 reallocateMemoryChecks(address, bytes);
615
616 if (bytes == 0) {
617 freeMemory(address);
618 return 0;
619 }
620
621 long p = (address == 0) ? allocateMemory0(bytes) : reallocateMemory0(address, bytes);
622 if (p == 0) {
623 throw new OutOfMemoryError();
624 }
625
626 return p;
627 }
628
629 /**
630 * Validate the arguments to reallocateMemory
631 *
632 * @throws RuntimeException if the arguments are invalid
633 * (<em>Note:</em> after optimization, invalid inputs may
634 * go undetected, which will lead to unpredictable
635 * behavior)
636 */
637 private void reallocateMemoryChecks(long address, long bytes) {
638 checkPointer(null, address);
639 checkSize(bytes);
640 }
641
642 /**
643 * Sets all bytes in a given block of memory to a fixed value
644 * (usually zero).
645 *
646 * <p>This method determines a block's base address by means of two parameters,
647 * and so it provides (in effect) a <em>double-register</em> addressing mode,
648 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
649 * the offset supplies an absolute base address.
650 *
651 * <p>The stores are in coherent (atomic) units of a size determined
652 * by the address and length parameters. If the effective address and
653 * length are all even modulo 8, the stores take place in 'long' units.
654 * If the effective address and length are (resp.) even modulo 4 or 2,
655 * the stores take place in units of 'int' or 'short'.
656 *
657 * <em>Note:</em> It is the resposibility of the caller to make
658 * sure arguments are checked before the methods are called. While
659 * some rudimentary checks are performed on the input, the checks
660 * are best effort and when performance is an overriding priority,
661 * as when methods of this class are optimized by the runtime
662 * compiler, some or all checks (if any) may be elided. Hence, the
663 * caller must not rely on the checks and corresponding
664 * exceptions!
665 *
666 * @throws RuntimeException if any of the arguments is invalid
667 *
668 * @since 1.7
669 */
670 public void setMemory(Object o, long offset, long bytes, byte value) {
671 setMemoryChecks(o, offset, bytes, value);
672
673 if (bytes == 0) {
674 return;
675 }
676
677 setMemory0(o, offset, bytes, value);
678 }
679
680 /**
681 * Sets all bytes in a given block of memory to a fixed value
682 * (usually zero). This provides a <em>single-register</em> addressing mode,
683 * as discussed in {@link #getInt(Object,long)}.
684 *
685 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
686 */
687 public void setMemory(long address, long bytes, byte value) {
688 setMemory(null, address, bytes, value);
689 }
690
691 /**
692 * Validate the arguments to setMemory
693 *
694 * @throws RuntimeException if the arguments are invalid
695 * (<em>Note:</em> after optimization, invalid inputs may
696 * go undetected, which will lead to unpredictable
697 * behavior)
698 */
699 private void setMemoryChecks(Object o, long offset, long bytes, byte value) {
700 checkPrimitivePointer(o, offset);
701 checkSize(bytes);
702 }
703
704 /**
705 * Sets all bytes in a given block of memory to a copy of another
706 * block.
707 *
708 * <p>This method determines each block's base address by means of two parameters,
709 * and so it provides (in effect) a <em>double-register</em> addressing mode,
710 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
711 * the offset supplies an absolute base address.
712 *
713 * <p>The transfers are in coherent (atomic) units of a size determined
714 * by the address and length parameters. If the effective addresses and
715 * length are all even modulo 8, the transfer takes place in 'long' units.
716 * If the effective addresses and length are (resp.) even modulo 4 or 2,
717 * the transfer takes place in units of 'int' or 'short'.
718 *
719 * <em>Note:</em> It is the resposibility of the caller to make
720 * sure arguments are checked before the methods are called. While
721 * some rudimentary checks are performed on the input, the checks
722 * are best effort and when performance is an overriding priority,
723 * as when methods of this class are optimized by the runtime
724 * compiler, some or all checks (if any) may be elided. Hence, the
725 * caller must not rely on the checks and corresponding
726 * exceptions!
727 *
728 * @throws RuntimeException if any of the arguments is invalid
729 *
730 * @since 1.7
731 */
732 public void copyMemory(Object srcBase, long srcOffset,
733 Object destBase, long destOffset,
734 long bytes) {
735 copyMemoryChecks(srcBase, srcOffset, destBase, destOffset, bytes);
736
737 if (bytes == 0) {
738 return;
739 }
740
741 copyMemory0(srcBase, srcOffset, destBase, destOffset, bytes);
742 }
743
744 /**
745 * Sets all bytes in a given block of memory to a copy of another
746 * block. This provides a <em>single-register</em> addressing mode,
747 * as discussed in {@link #getInt(Object,long)}.
748 *
749 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
750 */
751 public void copyMemory(long srcAddress, long destAddress, long bytes) {
752 copyMemory(null, srcAddress, null, destAddress, bytes);
753 }
754
755 /**
756 * Validate the arguments to copyMemory
757 *
758 * @throws RuntimeException if any of the arguments is invalid
759 * (<em>Note:</em> after optimization, invalid inputs may
760 * go undetected, which will lead to unpredictable
761 * behavior)
762 */
763 private void copyMemoryChecks(Object srcBase, long srcOffset,
764 Object destBase, long destOffset,
765 long bytes) {
766 checkSize(bytes);
767 checkPrimitivePointer(srcBase, srcOffset);
768 checkPrimitivePointer(destBase, destOffset);
769 }
770
771 /**
772 * Copies all elements from one block of memory to another block,
773 * *unconditionally* byte swapping the elements on the fly.
774 *
775 * <p>This method determines each block's base address by means of two parameters,
776 * and so it provides (in effect) a <em>double-register</em> addressing mode,
777 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
778 * the offset supplies an absolute base address.
779 *
780 * <em>Note:</em> It is the resposibility of the caller to make
781 * sure arguments are checked before the methods are called. While
782 * some rudimentary checks are performed on the input, the checks
783 * are best effort and when performance is an overriding priority,
784 * as when methods of this class are optimized by the runtime
785 * compiler, some or all checks (if any) may be elided. Hence, the
786 * caller must not rely on the checks and corresponding
787 * exceptions!
788 *
789 * @throws RuntimeException if any of the arguments is invalid
790 *
791 * @since 9
792 */
793 public void copySwapMemory(Object srcBase, long srcOffset,
794 Object destBase, long destOffset,
795 long bytes, long elemSize) {
796 copySwapMemoryChecks(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
797
798 if (bytes == 0) {
799 return;
800 }
801
802 copySwapMemory0(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
803 }
804
805 private void copySwapMemoryChecks(Object srcBase, long srcOffset,
806 Object destBase, long destOffset,
807 long bytes, long elemSize) {
808 checkSize(bytes);
809
810 if (elemSize != 2 && elemSize != 4 && elemSize != 8) {
811 throw invalidInput();
812 }
813 if (bytes % elemSize != 0) {
814 throw invalidInput();
815 }
816
817 checkPrimitivePointer(srcBase, srcOffset);
818 checkPrimitivePointer(destBase, destOffset);
819 }
820
821 /**
822 * Copies all elements from one block of memory to another block, byte swapping the
823 * elements on the fly.
824 *
825 * This provides a <em>single-register</em> addressing mode, as
826 * discussed in {@link #getInt(Object,long)}.
827 *
828 * Equivalent to {@code copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize)}.
829 */
830 public void copySwapMemory(long srcAddress, long destAddress, long bytes, long elemSize) {
831 copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize);
832 }
833
834 /**
835 * Disposes of a block of native memory, as obtained from {@link
836 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
837 * this method may be null, in which case no action is taken.
838 *
839 * <em>Note:</em> It is the resposibility of the caller to make
840 * sure arguments are checked before the methods are called. While
841 * some rudimentary checks are performed on the input, the checks
842 * are best effort and when performance is an overriding priority,
843 * as when methods of this class are optimized by the runtime
844 * compiler, some or all checks (if any) may be elided. Hence, the
845 * caller must not rely on the checks and corresponding
846 * exceptions!
847 *
848 * @throws RuntimeException if any of the arguments is invalid
849 *
850 * @see #allocateMemory
851 */
852 public void freeMemory(long address) {
853 freeMemoryChecks(address);
854
855 if (address == 0) {
856 return;
857 }
858
859 freeMemory0(address);
860 }
861
862 /**
863 * Validate the arguments to freeMemory
864 *
865 * @throws RuntimeException if the arguments are invalid
866 * (<em>Note:</em> after optimization, invalid inputs may
867 * go undetected, which will lead to unpredictable
868 * behavior)
869 */
870 private void freeMemoryChecks(long address) {
871 checkPointer(null, address);
872 }
873
874 /// random queries
875
876 /**
877 * This constant differs from all results that will ever be returned from
878 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
879 * or {@link #arrayBaseOffset}.
880 */
881 public static final int INVALID_FIELD_OFFSET = -1;
882
883 /**
884 * Reports the location of a given field in the storage allocation of its
885 * class. Do not expect to perform any sort of arithmetic on this offset;
886 * it is just a cookie which is passed to the unsafe heap memory accessors.
887 *
888 * <p>Any given field will always have the same offset and base, and no
889 * two distinct fields of the same class will ever have the same offset
890 * and base.
891 *
892 * <p>As of 1.4.1, offsets for fields are represented as long values,
893 * although the Sun JVM does not use the most significant 32 bits.
894 * However, JVM implementations which store static fields at absolute
895 * addresses can use long offsets and null base pointers to express
896 * the field locations in a form usable by {@link #getInt(Object,long)}.
897 * Therefore, code which will be ported to such JVMs on 64-bit platforms
898 * must preserve all bits of static field offsets.
899 * @see #getInt(Object, long)
900 */
901 public long objectFieldOffset(Field f) {
902 if (f == null) {
903 throw new NullPointerException();
904 }
905
906 return objectFieldOffset0(f);
907 }
908
909 /**
910 * Reports the location of a given static field, in conjunction with {@link
911 * #staticFieldBase}.
912 * <p>Do not expect to perform any sort of arithmetic on this offset;
913 * it is just a cookie which is passed to the unsafe heap memory accessors.
914 *
915 * <p>Any given field will always have the same offset, and no two distinct
916 * fields of the same class will ever have the same offset.
917 *
918 * <p>As of 1.4.1, offsets for fields are represented as long values,
919 * although the Sun JVM does not use the most significant 32 bits.
920 * It is hard to imagine a JVM technology which needs more than
921 * a few bits to encode an offset within a non-array object,
922 * However, for consistency with other methods in this class,
923 * this method reports its result as a long value.
924 * @see #getInt(Object, long)
925 */
926 public long staticFieldOffset(Field f) {
927 if (f == null) {
928 throw new NullPointerException();
929 }
930
931 return staticFieldOffset0(f);
932 }
933
934 /**
935 * Reports the location of a given static field, in conjunction with {@link
936 * #staticFieldOffset}.
937 * <p>Fetch the base "Object", if any, with which static fields of the
938 * given class can be accessed via methods like {@link #getInt(Object,
939 * long)}. This value may be null. This value may refer to an object
940 * which is a "cookie", not guaranteed to be a real Object, and it should
941 * not be used in any way except as argument to the get and put routines in
942 * this class.
943 */
944 public Object staticFieldBase(Field f) {
945 if (f == null) {
946 throw new NullPointerException();
947 }
948
949 return staticFieldBase0(f);
950 }
951
952 /**
953 * Detects if the given class may need to be initialized. This is often
954 * needed in conjunction with obtaining the static field base of a
955 * class.
956 * @return false only if a call to {@code ensureClassInitialized} would have no effect
957 */
958 public boolean shouldBeInitialized(Class<?> c) {
959 if (c == null) {
960 throw new NullPointerException();
961 }
962
963 return shouldBeInitialized0(c);
964 }
965
966 /**
967 * Ensures the given class has been initialized. This is often
968 * needed in conjunction with obtaining the static field base of a
969 * class.
970 */
971 public void ensureClassInitialized(Class<?> c) {
972 if (c == null) {
973 throw new NullPointerException();
974 }
975
976 ensureClassInitialized0(c);
977 }
978
979 /**
980 * Reports the offset of the first element in the storage allocation of a
981 * given array class. If {@link #arrayIndexScale} returns a non-zero value
982 * for the same class, you may use that scale factor, together with this
983 * base offset, to form new offsets to access elements of arrays of the
984 * given class.
985 *
986 * @see #getInt(Object, long)
987 * @see #putInt(Object, long, int)
988 */
989 public int arrayBaseOffset(Class<?> arrayClass) {
990 if (arrayClass == null) {
991 throw new NullPointerException();
992 }
993
994 return arrayBaseOffset0(arrayClass);
995 }
996
997
998 /** The value of {@code arrayBaseOffset(boolean[].class)} */
999 public static final int ARRAY_BOOLEAN_BASE_OFFSET
1000 = theUnsafe.arrayBaseOffset(boolean[].class);
1001
1002 /** The value of {@code arrayBaseOffset(byte[].class)} */
1003 public static final int ARRAY_BYTE_BASE_OFFSET
1004 = theUnsafe.arrayBaseOffset(byte[].class);
1005
1006 /** The value of {@code arrayBaseOffset(short[].class)} */
1007 public static final int ARRAY_SHORT_BASE_OFFSET
1008 = theUnsafe.arrayBaseOffset(short[].class);
1009
1010 /** The value of {@code arrayBaseOffset(char[].class)} */
1011 public static final int ARRAY_CHAR_BASE_OFFSET
1012 = theUnsafe.arrayBaseOffset(char[].class);
1013
1014 /** The value of {@code arrayBaseOffset(int[].class)} */
1015 public static final int ARRAY_INT_BASE_OFFSET
1016 = theUnsafe.arrayBaseOffset(int[].class);
1017
1018 /** The value of {@code arrayBaseOffset(long[].class)} */
1019 public static final int ARRAY_LONG_BASE_OFFSET
1020 = theUnsafe.arrayBaseOffset(long[].class);
1021
1022 /** The value of {@code arrayBaseOffset(float[].class)} */
1023 public static final int ARRAY_FLOAT_BASE_OFFSET
1024 = theUnsafe.arrayBaseOffset(float[].class);
1025
1026 /** The value of {@code arrayBaseOffset(double[].class)} */
1027 public static final int ARRAY_DOUBLE_BASE_OFFSET
1028 = theUnsafe.arrayBaseOffset(double[].class);
1029
1030 /** The value of {@code arrayBaseOffset(Object[].class)} */
1031 public static final int ARRAY_OBJECT_BASE_OFFSET
1032 = theUnsafe.arrayBaseOffset(Object[].class);
1033
1034 /**
1035 * Reports the scale factor for addressing elements in the storage
1036 * allocation of a given array class. However, arrays of "narrow" types
1037 * will generally not work properly with accessors like {@link
1038 * #getByte(Object, long)}, so the scale factor for such classes is reported
1039 * as zero.
1040 *
1041 * @see #arrayBaseOffset
1042 * @see #getInt(Object, long)
1043 * @see #putInt(Object, long, int)
1044 */
1045 public int arrayIndexScale(Class<?> arrayClass) {
1046 if (arrayClass == null) {
1047 throw new NullPointerException();
1048 }
1049
1050 return arrayIndexScale0(arrayClass);
1051 }
1052
1053
1054 /** The value of {@code arrayIndexScale(boolean[].class)} */
1055 public static final int ARRAY_BOOLEAN_INDEX_SCALE
1056 = theUnsafe.arrayIndexScale(boolean[].class);
1057
1058 /** The value of {@code arrayIndexScale(byte[].class)} */
1059 public static final int ARRAY_BYTE_INDEX_SCALE
1060 = theUnsafe.arrayIndexScale(byte[].class);
1061
1062 /** The value of {@code arrayIndexScale(short[].class)} */
1063 public static final int ARRAY_SHORT_INDEX_SCALE
1064 = theUnsafe.arrayIndexScale(short[].class);
1065
1066 /** The value of {@code arrayIndexScale(char[].class)} */
1067 public static final int ARRAY_CHAR_INDEX_SCALE
1068 = theUnsafe.arrayIndexScale(char[].class);
1069
1070 /** The value of {@code arrayIndexScale(int[].class)} */
1071 public static final int ARRAY_INT_INDEX_SCALE
1072 = theUnsafe.arrayIndexScale(int[].class);
1073
1074 /** The value of {@code arrayIndexScale(long[].class)} */
1075 public static final int ARRAY_LONG_INDEX_SCALE
1076 = theUnsafe.arrayIndexScale(long[].class);
1077
1078 /** The value of {@code arrayIndexScale(float[].class)} */
1079 public static final int ARRAY_FLOAT_INDEX_SCALE
1080 = theUnsafe.arrayIndexScale(float[].class);
1081
1082 /** The value of {@code arrayIndexScale(double[].class)} */
1083 public static final int ARRAY_DOUBLE_INDEX_SCALE
1084 = theUnsafe.arrayIndexScale(double[].class);
1085
1086 /** The value of {@code arrayIndexScale(Object[].class)} */
1087 public static final int ARRAY_OBJECT_INDEX_SCALE
1088 = theUnsafe.arrayIndexScale(Object[].class);
1089
1090 /**
1091 * Reports the size in bytes of a native pointer, as stored via {@link
1092 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
1093 * other primitive types (as stored in native memory blocks) is determined
1094 * fully by their information content.
1095 */
1096 public int addressSize() {
1097 return ADDRESS_SIZE;
1098 }
1099
1100 /** The value of {@code addressSize()} */
1101 public static final int ADDRESS_SIZE = theUnsafe.addressSize0();
1102
1103 /**
1104 * Reports the size in bytes of a native memory page (whatever that is).
1105 * This value will always be a power of two.
1106 */
1107 public native int pageSize();
1108
1109
1110 /// random trusted operations from JNI:
1111
1112 /**
1113 * Tells the VM to define a class, without security checks. By default, the
1114 * class loader and protection domain come from the caller's class.
1115 */
1116 public Class<?> defineClass(String name, byte[] b, int off, int len,
1117 ClassLoader loader,
1118 ProtectionDomain protectionDomain) {
1119 if (b == null) {
1120 throw new NullPointerException();
1121 }
1122 if (len < 0) {
1123 throw new ArrayIndexOutOfBoundsException();
1124 }
1125
1126 return defineClass0(name, b, off, len, loader, protectionDomain);
1127 }
1128
1129 public native Class<?> defineClass0(String name, byte[] b, int off, int len,
1130 ClassLoader loader,
1131 ProtectionDomain protectionDomain);
1132
1133 /**
1134 * Defines a class but does not make it known to the class loader or system dictionary.
1135 * <p>
1136 * For each CP entry, the corresponding CP patch must either be null or have
1137 * the a format that matches its tag:
1138 * <ul>
1139 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
1140 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
1141 * <li>Class: any java.lang.Class object
1142 * <li>String: any object (not just a java.lang.String)
1143 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
1144 * </ul>
1145 * @param hostClass context for linkage, access control, protection domain, and class loader
1146 * @param data bytes of a class file
1147 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
1148 */
1149 public Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches) {
1150 if (hostClass == null || data == null) {
1151 throw new NullPointerException();
1152 }
1153
1154 return defineAnonymousClass0(hostClass, data, cpPatches);
1155 }
1156
1157 /**
1158 * Allocates an instance but does not run any constructor.
1159 * Initializes the class if it has not yet been.
1160 */
1161 @ForceInline
1162 public Object allocateInstance(Class<?> cls) throws InstantiationException {
1163 // Interfaces and abstract classes are handled by the intrinsic.
1164 if (cls.isPrimitive() || cls.isArray()) {
1165 throw new InstantiationException(cls.getName());
1166 }
1167 return allocateInstance0(cls);
1168 }
1169
1170 @HotSpotIntrinsicCandidate
1171 private native Object allocateInstance0(Class<?> cls) throws InstantiationException;
1172
1173 /**
1174 * Allocates an array of a given type, but does not do zeroing.
1175 * <p>
1176 * This method should only be used in the very rare cases where a high-performance code
1177 * overwrites the destination array completely, and compilers cannot assist in zeroing elimination.
1178 * In an overwhelming majority of cases, a normal Java allocation should be used instead.
1179 * <p>
1180 * Users of this method are <b>required</b> to overwrite the initial (garbage) array contents
1181 * before allowing untrusted code, or code in other threads, to observe the reference
1182 * to the newly allocated array. In addition, the publication of the array reference must be
1183 * safe according to the Java Memory Model requirements.
1184 * <p>
1185 * The safest approach to deal with an uninitialized array is to keep the reference to it in local
1186 * variable at least until the initialization is complete, and then publish it <b>once</b>, either
1187 * by writing it to a <em>volatile</em> field, or storing it into a <em>final</em> field in constructor,
1188 * or issuing a {@link #storeFence} before publishing the reference.
1189 * <p>
1190 * @implnote This method can only allocate primitive arrays, to avoid garbage reference
1191 * elements that could break heap integrity.
1192 *
1193 * @param componentType array component type to allocate
1194 * @param length array size to allocate
1195 * @throws IllegalArgumentException if component type is null, or not a primitive class;
1196 * or the length is negative
1197 */
1198 public Object allocateUninitializedArray(Class<?> componentType, int length) {
1199 if (componentType == null) {
1200 throw new IllegalArgumentException("Component type is null");
1201 }
1202 if (!componentType.isPrimitive()) {
1203 throw new IllegalArgumentException("Component type is not primitive");
1204 }
1205 if (length < 0) {
1206 throw new IllegalArgumentException("Negative length");
1207 }
1208 return allocateUninitializedArray0(componentType, length);
1209 }
1210
1211 @HotSpotIntrinsicCandidate
1212 private Object allocateUninitializedArray0(Class<?> componentType, int length) {
1213 // These fallbacks provide zeroed arrays, but intrinsic is not required to
1214 // return the zeroed arrays.
1215 if (componentType == byte.class) return new byte[length];
1216 if (componentType == boolean.class) return new boolean[length];
1217 if (componentType == short.class) return new short[length];
1218 if (componentType == char.class) return new char[length];
1219 if (componentType == int.class) return new int[length];
1220 if (componentType == float.class) return new float[length];
1221 if (componentType == long.class) return new long[length];
1222 if (componentType == double.class) return new double[length];
1223 return null;
1224 }
1225
1226 /** Throws the exception without telling the verifier. */
1227 public native void throwException(Throwable ee);
1228
1229 /**
1230 * Atomically updates Java variable to {@code x} if it is currently
1231 * holding {@code expected}.
1232 *
1233 * <p>This operation has memory semantics of a {@code volatile} read
1234 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1235 *
1236 * @return {@code true} if successful
1237 */
1238 @HotSpotIntrinsicCandidate
1239 public final native boolean compareAndSwapObject(Object o, long offset,
1240 Object expected,
1241 Object x);
1242
1243 @HotSpotIntrinsicCandidate
1244 public final native Object compareAndExchangeObjectVolatile(Object o, long offset,
1245 Object expected,
1246 Object x);
1247
1248 @HotSpotIntrinsicCandidate
1249 public final Object compareAndExchangeObjectAcquire(Object o, long offset,
1250 Object expected,
1251 Object x) {
1252 return compareAndExchangeObjectVolatile(o, offset, expected, x);
1253 }
1254
1255 @HotSpotIntrinsicCandidate
1256 public final Object compareAndExchangeObjectRelease(Object o, long offset,
1257 Object expected,
1258 Object x) {
1259 return compareAndExchangeObjectVolatile(o, offset, expected, x);
1260 }
1261
1262 @HotSpotIntrinsicCandidate
1263 public final boolean weakCompareAndSwapObject(Object o, long offset,
1264 Object expected,
1265 Object x) {
1266 return compareAndSwapObject(o, offset, expected, x);
1267 }
1268
1269 @HotSpotIntrinsicCandidate
1270 public final boolean weakCompareAndSwapObjectAcquire(Object o, long offset,
1271 Object expected,
1272 Object x) {
1273 return compareAndSwapObject(o, offset, expected, x);
1274 }
1275
1276 @HotSpotIntrinsicCandidate
1277 public final boolean weakCompareAndSwapObjectRelease(Object o, long offset,
1278 Object expected,
1279 Object x) {
1280 return compareAndSwapObject(o, offset, expected, x);
1281 }
1282
1283 /**
1284 * Atomically updates Java variable to {@code x} if it is currently
1285 * holding {@code expected}.
1286 *
1287 * <p>This operation has memory semantics of a {@code volatile} read
1288 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1289 *
1290 * @return {@code true} if successful
1291 */
1292 @HotSpotIntrinsicCandidate
1293 public final native boolean compareAndSwapInt(Object o, long offset,
1294 int expected,
1295 int x);
1296
1297 @HotSpotIntrinsicCandidate
1298 public final native int compareAndExchangeIntVolatile(Object o, long offset,
1299 int expected,
1300 int x);
1301
1302 @HotSpotIntrinsicCandidate
1303 public final int compareAndExchangeIntAcquire(Object o, long offset,
1304 int expected,
1305 int x) {
1306 return compareAndExchangeIntVolatile(o, offset, expected, x);
1307 }
1308
1309 @HotSpotIntrinsicCandidate
1310 public final int compareAndExchangeIntRelease(Object o, long offset,
1311 int expected,
1312 int x) {
1313 return compareAndExchangeIntVolatile(o, offset, expected, x);
1314 }
1315
1316 @HotSpotIntrinsicCandidate
1317 public final boolean weakCompareAndSwapInt(Object o, long offset,
1318 int expected,
1319 int x) {
1320 return compareAndSwapInt(o, offset, expected, x);
1321 }
1322
1323 @HotSpotIntrinsicCandidate
1324 public final boolean weakCompareAndSwapIntAcquire(Object o, long offset,
1325 int expected,
1326 int x) {
1327 return compareAndSwapInt(o, offset, expected, x);
1328 }
1329
1330 @HotSpotIntrinsicCandidate
1331 public final boolean weakCompareAndSwapIntRelease(Object o, long offset,
1332 int expected,
1333 int x) {
1334 return compareAndSwapInt(o, offset, expected, x);
1335 }
1336
1337 /**
1338 * Atomically updates Java variable to {@code x} if it is currently
1339 * holding {@code expected}.
1340 *
1341 * <p>This operation has memory semantics of a {@code volatile} read
1342 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1343 *
1344 * @return {@code true} if successful
1345 */
1346 @HotSpotIntrinsicCandidate
1347 public final native boolean compareAndSwapLong(Object o, long offset,
1348 long expected,
1349 long x);
1350
1351 @HotSpotIntrinsicCandidate
1352 public final native long compareAndExchangeLongVolatile(Object o, long offset,
1353 long expected,
1354 long x);
1355
1356 @HotSpotIntrinsicCandidate
1357 public final long compareAndExchangeLongAcquire(Object o, long offset,
1358 long expected,
1359 long x) {
1360 return compareAndExchangeLongVolatile(o, offset, expected, x);
1361 }
1362
1363 @HotSpotIntrinsicCandidate
1364 public final long compareAndExchangeLongRelease(Object o, long offset,
1365 long expected,
1366 long x) {
1367 return compareAndExchangeLongVolatile(o, offset, expected, x);
1368 }
1369
1370 @HotSpotIntrinsicCandidate
1371 public final boolean weakCompareAndSwapLong(Object o, long offset,
1372 long expected,
1373 long x) {
1374 return compareAndSwapLong(o, offset, expected, x);
1375 }
1376
1377 @HotSpotIntrinsicCandidate
1378 public final boolean weakCompareAndSwapLongAcquire(Object o, long offset,
1379 long expected,
1380 long x) {
1381 return compareAndSwapLong(o, offset, expected, x);
1382 }
1383
1384 @HotSpotIntrinsicCandidate
1385 public final boolean weakCompareAndSwapLongRelease(Object o, long offset,
1386 long expected,
1387 long x) {
1388 return compareAndSwapLong(o, offset, expected, x);
1389 }
1390
1391 /**
1392 * Fetches a reference value from a given Java variable, with volatile
1393 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
1394 */
1395 @HotSpotIntrinsicCandidate
1396 public native Object getObjectVolatile(Object o, long offset);
1397
1398 /**
1399 * Stores a reference value into a given Java variable, with
1400 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
1401 */
1402 @HotSpotIntrinsicCandidate
1403 public native void putObjectVolatile(Object o, long offset, Object x);
1404
1405 /** Volatile version of {@link #getInt(Object, long)} */
1406 @HotSpotIntrinsicCandidate
1407 public native int getIntVolatile(Object o, long offset);
1408
1409 /** Volatile version of {@link #putInt(Object, long, int)} */
1410 @HotSpotIntrinsicCandidate
1411 public native void putIntVolatile(Object o, long offset, int x);
1412
1413 /** Volatile version of {@link #getBoolean(Object, long)} */
1414 @HotSpotIntrinsicCandidate
1415 public native boolean getBooleanVolatile(Object o, long offset);
1416
1417 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
1418 @HotSpotIntrinsicCandidate
1419 public native void putBooleanVolatile(Object o, long offset, boolean x);
1420
1421 /** Volatile version of {@link #getByte(Object, long)} */
1422 @HotSpotIntrinsicCandidate
1423 public native byte getByteVolatile(Object o, long offset);
1424
1425 /** Volatile version of {@link #putByte(Object, long, byte)} */
1426 @HotSpotIntrinsicCandidate
1427 public native void putByteVolatile(Object o, long offset, byte x);
1428
1429 /** Volatile version of {@link #getShort(Object, long)} */
1430 @HotSpotIntrinsicCandidate
1431 public native short getShortVolatile(Object o, long offset);
1432
1433 /** Volatile version of {@link #putShort(Object, long, short)} */
1434 @HotSpotIntrinsicCandidate
1435 public native void putShortVolatile(Object o, long offset, short x);
1436
1437 /** Volatile version of {@link #getChar(Object, long)} */
1438 @HotSpotIntrinsicCandidate
1439 public native char getCharVolatile(Object o, long offset);
1440
1441 /** Volatile version of {@link #putChar(Object, long, char)} */
1442 @HotSpotIntrinsicCandidate
1443 public native void putCharVolatile(Object o, long offset, char x);
1444
1445 /** Volatile version of {@link #getLong(Object, long)} */
1446 @HotSpotIntrinsicCandidate
1447 public native long getLongVolatile(Object o, long offset);
1448
1449 /** Volatile version of {@link #putLong(Object, long, long)} */
1450 @HotSpotIntrinsicCandidate
1451 public native void putLongVolatile(Object o, long offset, long x);
1452
1453 /** Volatile version of {@link #getFloat(Object, long)} */
1454 @HotSpotIntrinsicCandidate
1455 public native float getFloatVolatile(Object o, long offset);
1456
1457 /** Volatile version of {@link #putFloat(Object, long, float)} */
1458 @HotSpotIntrinsicCandidate
1459 public native void putFloatVolatile(Object o, long offset, float x);
1460
1461 /** Volatile version of {@link #getDouble(Object, long)} */
1462 @HotSpotIntrinsicCandidate
1463 public native double getDoubleVolatile(Object o, long offset);
1464
1465 /** Volatile version of {@link #putDouble(Object, long, double)} */
1466 @HotSpotIntrinsicCandidate
1467 public native void putDoubleVolatile(Object o, long offset, double x);
1468
1469
1470
1471 /** Acquire version of {@link #getObjectVolatile(Object, long)} */
1472 @HotSpotIntrinsicCandidate
1473 public final Object getObjectAcquire(Object o, long offset) {
1474 return getObjectVolatile(o, offset);
1475 }
1476
1477 /** Acquire version of {@link #getBooleanVolatile(Object, long)} */
1478 @HotSpotIntrinsicCandidate
1479 public final boolean getBooleanAcquire(Object o, long offset) {
1480 return getBooleanVolatile(o, offset);
1481 }
1482
1483 /** Acquire version of {@link #getByteVolatile(Object, long)} */
1484 @HotSpotIntrinsicCandidate
1485 public final byte getByteAcquire(Object o, long offset) {
1486 return getByteVolatile(o, offset);
1487 }
1488
1489 /** Acquire version of {@link #getShortVolatile(Object, long)} */
1490 @HotSpotIntrinsicCandidate
1491 public final short getShortAcquire(Object o, long offset) {
1492 return getShortVolatile(o, offset);
1493 }
1494
1495 /** Acquire version of {@link #getCharVolatile(Object, long)} */
1496 @HotSpotIntrinsicCandidate
1497 public final char getCharAcquire(Object o, long offset) {
1498 return getCharVolatile(o, offset);
1499 }
1500
1501 /** Acquire version of {@link #getIntVolatile(Object, long)} */
1502 @HotSpotIntrinsicCandidate
1503 public final int getIntAcquire(Object o, long offset) {
1504 return getIntVolatile(o, offset);
1505 }
1506
1507 /** Acquire version of {@link #getFloatVolatile(Object, long)} */
1508 @HotSpotIntrinsicCandidate
1509 public final float getFloatAcquire(Object o, long offset) {
1510 return getFloatVolatile(o, offset);
1511 }
1512
1513 /** Acquire version of {@link #getLongVolatile(Object, long)} */
1514 @HotSpotIntrinsicCandidate
1515 public final long getLongAcquire(Object o, long offset) {
1516 return getLongVolatile(o, offset);
1517 }
1518
1519 /** Acquire version of {@link #getDoubleVolatile(Object, long)} */
1520 @HotSpotIntrinsicCandidate
1521 public final double getDoubleAcquire(Object o, long offset) {
1522 return getDoubleVolatile(o, offset);
1523 }
1524
1525 /*
1526 * Versions of {@link #putObjectVolatile(Object, long, Object)}
1527 * that do not guarantee immediate visibility of the store to
1528 * other threads. This method is generally only useful if the
1529 * underlying field is a Java volatile (or if an array cell, one
1530 * that is otherwise only accessed using volatile accesses).
1531 *
1532 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1533 */
1534
1535 /** Release version of {@link #putObjectVolatile(Object, long, Object)} */
1536 @HotSpotIntrinsicCandidate
1537 public final void putObjectRelease(Object o, long offset, Object x) {
1538 putObjectVolatile(o, offset, x);
1539 }
1540
1541 /** Release version of {@link #putBooleanVolatile(Object, long, boolean)} */
1542 @HotSpotIntrinsicCandidate
1543 public final void putBooleanRelease(Object o, long offset, boolean x) {
1544 putBooleanVolatile(o, offset, x);
1545 }
1546
1547 /** Release version of {@link #putByteVolatile(Object, long, byte)} */
1548 @HotSpotIntrinsicCandidate
1549 public final void putByteRelease(Object o, long offset, byte x) {
1550 putByteVolatile(o, offset, x);
1551 }
1552
1553 /** Release version of {@link #putShortVolatile(Object, long, short)} */
1554 @HotSpotIntrinsicCandidate
1555 public final void putShortRelease(Object o, long offset, short x) {
1556 putShortVolatile(o, offset, x);
1557 }
1558
1559 /** Release version of {@link #putCharVolatile(Object, long, char)} */
1560 @HotSpotIntrinsicCandidate
1561 public final void putCharRelease(Object o, long offset, char x) {
1562 putCharVolatile(o, offset, x);
1563 }
1564
1565 /** Release version of {@link #putIntVolatile(Object, long, int)} */
1566 @HotSpotIntrinsicCandidate
1567 public final void putIntRelease(Object o, long offset, int x) {
1568 putIntVolatile(o, offset, x);
1569 }
1570
1571 /** Release version of {@link #putFloatVolatile(Object, long, float)} */
1572 @HotSpotIntrinsicCandidate
1573 public final void putFloatRelease(Object o, long offset, float x) {
1574 putFloatVolatile(o, offset, x);
1575 }
1576
1577 /** Release version of {@link #putLongVolatile(Object, long, long)} */
1578 @HotSpotIntrinsicCandidate
1579 public final void putLongRelease(Object o, long offset, long x) {
1580 putLongVolatile(o, offset, x);
1581 }
1582
1583 /** Release version of {@link #putDoubleVolatile(Object, long, double)} */
1584 @HotSpotIntrinsicCandidate
1585 public final void putDoubleRelease(Object o, long offset, double x) {
1586 putDoubleVolatile(o, offset, x);
1587 }
1588
1589 // ------------------------------ Opaque --------------------------------------
1590
1591 /** Opaque version of {@link #getObjectVolatile(Object, long)} */
1592 @HotSpotIntrinsicCandidate
1593 public final Object getObjectOpaque(Object o, long offset) {
1594 return getObjectVolatile(o, offset);
1595 }
1596
1597 /** Opaque version of {@link #getBooleanVolatile(Object, long)} */
1598 @HotSpotIntrinsicCandidate
1599 public final boolean getBooleanOpaque(Object o, long offset) {
1600 return getBooleanVolatile(o, offset);
1601 }
1602
1603 /** Opaque version of {@link #getByteVolatile(Object, long)} */
1604 @HotSpotIntrinsicCandidate
1605 public final byte getByteOpaque(Object o, long offset) {
1606 return getByteVolatile(o, offset);
1607 }
1608
1609 /** Opaque version of {@link #getShortVolatile(Object, long)} */
1610 @HotSpotIntrinsicCandidate
1611 public final short getShortOpaque(Object o, long offset) {
1612 return getShortVolatile(o, offset);
1613 }
1614
1615 /** Opaque version of {@link #getCharVolatile(Object, long)} */
1616 @HotSpotIntrinsicCandidate
1617 public final char getCharOpaque(Object o, long offset) {
1618 return getCharVolatile(o, offset);
1619 }
1620
1621 /** Opaque version of {@link #getIntVolatile(Object, long)} */
1622 @HotSpotIntrinsicCandidate
1623 public final int getIntOpaque(Object o, long offset) {
1624 return getIntVolatile(o, offset);
1625 }
1626
1627 /** Opaque version of {@link #getFloatVolatile(Object, long)} */
1628 @HotSpotIntrinsicCandidate
1629 public final float getFloatOpaque(Object o, long offset) {
1630 return getFloatVolatile(o, offset);
1631 }
1632
1633 /** Opaque version of {@link #getLongVolatile(Object, long)} */
1634 @HotSpotIntrinsicCandidate
1635 public final long getLongOpaque(Object o, long offset) {
1636 return getLongVolatile(o, offset);
1637 }
1638
1639 /** Opaque version of {@link #getDoubleVolatile(Object, long)} */
1640 @HotSpotIntrinsicCandidate
1641 public final double getDoubleOpaque(Object o, long offset) {
1642 return getDoubleVolatile(o, offset);
1643 }
1644
1645 /** Opaque version of {@link #putObjectVolatile(Object, long, Object)} */
1646 @HotSpotIntrinsicCandidate
1647 public final void putObjectOpaque(Object o, long offset, Object x) {
1648 putObjectVolatile(o, offset, x);
1649 }
1650
1651 /** Opaque version of {@link #putBooleanVolatile(Object, long, boolean)} */
1652 @HotSpotIntrinsicCandidate
1653 public final void putBooleanOpaque(Object o, long offset, boolean x) {
1654 putBooleanVolatile(o, offset, x);
1655 }
1656
1657 /** Opaque version of {@link #putByteVolatile(Object, long, byte)} */
1658 @HotSpotIntrinsicCandidate
1659 public final void putByteOpaque(Object o, long offset, byte x) {
1660 putByteVolatile(o, offset, x);
1661 }
1662
1663 /** Opaque version of {@link #putShortVolatile(Object, long, short)} */
1664 @HotSpotIntrinsicCandidate
1665 public final void putShortOpaque(Object o, long offset, short x) {
1666 putShortVolatile(o, offset, x);
1667 }
1668
1669 /** Opaque version of {@link #putCharVolatile(Object, long, char)} */
1670 @HotSpotIntrinsicCandidate
1671 public final void putCharOpaque(Object o, long offset, char x) {
1672 putCharVolatile(o, offset, x);
1673 }
1674
1675 /** Opaque version of {@link #putIntVolatile(Object, long, int)} */
1676 @HotSpotIntrinsicCandidate
1677 public final void putIntOpaque(Object o, long offset, int x) {
1678 putIntVolatile(o, offset, x);
1679 }
1680
1681 /** Opaque version of {@link #putFloatVolatile(Object, long, float)} */
1682 @HotSpotIntrinsicCandidate
1683 public final void putFloatOpaque(Object o, long offset, float x) {
1684 putFloatVolatile(o, offset, x);
1685 }
1686
1687 /** Opaque version of {@link #putLongVolatile(Object, long, long)} */
1688 @HotSpotIntrinsicCandidate
1689 public final void putLongOpaque(Object o, long offset, long x) {
1690 putLongVolatile(o, offset, x);
1691 }
1692
1693 /** Opaque version of {@link #putDoubleVolatile(Object, long, double)} */
1694 @HotSpotIntrinsicCandidate
1695 public final void putDoubleOpaque(Object o, long offset, double x) {
1696 putDoubleVolatile(o, offset, x);
1697 }
1698
1699 /**
1700 * Unblocks the given thread blocked on {@code park}, or, if it is
1701 * not blocked, causes the subsequent call to {@code park} not to
1702 * block. Note: this operation is "unsafe" solely because the
1703 * caller must somehow ensure that the thread has not been
1704 * destroyed. Nothing special is usually required to ensure this
1705 * when called from Java (in which there will ordinarily be a live
1706 * reference to the thread) but this is not nearly-automatically
1707 * so when calling from native code.
1708 *
1709 * @param thread the thread to unpark.
1710 */
1711 @HotSpotIntrinsicCandidate
1712 public native void unpark(Object thread);
1713
1714 /**
1715 * Blocks current thread, returning when a balancing
1716 * {@code unpark} occurs, or a balancing {@code unpark} has
1717 * already occurred, or the thread is interrupted, or, if not
1718 * absolute and time is not zero, the given time nanoseconds have
1719 * elapsed, or if absolute, the given deadline in milliseconds
1720 * since Epoch has passed, or spuriously (i.e., returning for no
1721 * "reason"). Note: This operation is in the Unsafe class only
1722 * because {@code unpark} is, so it would be strange to place it
1723 * elsewhere.
1724 */
1725 @HotSpotIntrinsicCandidate
1726 public native void park(boolean isAbsolute, long time);
1727
1728 /**
1729 * Gets the load average in the system run queue assigned
1730 * to the available processors averaged over various periods of time.
1731 * This method retrieves the given {@code nelem} samples and
1732 * assigns to the elements of the given {@code loadavg} array.
1733 * The system imposes a maximum of 3 samples, representing
1734 * averages over the last 1, 5, and 15 minutes, respectively.
1735 *
1736 * @param loadavg an array of double of size nelems
1737 * @param nelems the number of samples to be retrieved and
1738 * must be 1 to 3.
1739 *
1740 * @return the number of samples actually retrieved; or -1
1741 * if the load average is unobtainable.
1742 */
1743 public int getLoadAverage(double[] loadavg, int nelems) {
1744 if (nelems < 0 || nelems > 3 || nelems > loadavg.length) {
1745 throw new ArrayIndexOutOfBoundsException();
1746 }
1747
1748 return getLoadAverage0(loadavg, nelems);
1749 }
1750
1751 // The following contain CAS-based Java implementations used on
1752 // platforms not supporting native instructions
1753
1754 /**
1755 * Atomically adds the given value to the current value of a field
1756 * or array element within the given object {@code o}
1757 * at the given {@code offset}.
1758 *
1759 * @param o object/array to update the field/element in
1760 * @param offset field/element offset
1761 * @param delta the value to add
1762 * @return the previous value
1763 * @since 1.8
1764 */
1765 @HotSpotIntrinsicCandidate
1766 public final int getAndAddInt(Object o, long offset, int delta) {
1767 int v;
1768 do {
1769 v = getIntVolatile(o, offset);
1770 } while (!compareAndSwapInt(o, offset, v, v + delta));
1771 return v;
1772 }
1773
1774 /**
1775 * Atomically adds the given value to the current value of a field
1776 * or array element within the given object {@code o}
1777 * at the given {@code offset}.
1778 *
1779 * @param o object/array to update the field/element in
1780 * @param offset field/element offset
1781 * @param delta the value to add
1782 * @return the previous value
1783 * @since 1.8
1784 */
1785 @HotSpotIntrinsicCandidate
1786 public final long getAndAddLong(Object o, long offset, long delta) {
1787 long v;
1788 do {
1789 v = getLongVolatile(o, offset);
1790 } while (!compareAndSwapLong(o, offset, v, v + delta));
1791 return v;
1792 }
1793
1794 /**
1795 * Atomically exchanges the given value with the current value of
1796 * a field or array element within the given object {@code o}
1797 * at the given {@code offset}.
1798 *
1799 * @param o object/array to update the field/element in
1800 * @param offset field/element offset
1801 * @param newValue new value
1802 * @return the previous value
1803 * @since 1.8
1804 */
1805 @HotSpotIntrinsicCandidate
1806 public final int getAndSetInt(Object o, long offset, int newValue) {
1807 int v;
1808 do {
1809 v = getIntVolatile(o, offset);
1810 } while (!compareAndSwapInt(o, offset, v, newValue));
1811 return v;
1812 }
1813
1814 /**
1815 * Atomically exchanges the given value with the current value of
1816 * a field or array element within the given object {@code o}
1817 * at the given {@code offset}.
1818 *
1819 * @param o object/array to update the field/element in
1820 * @param offset field/element offset
1821 * @param newValue new value
1822 * @return the previous value
1823 * @since 1.8
1824 */
1825 @HotSpotIntrinsicCandidate
1826 public final long getAndSetLong(Object o, long offset, long newValue) {
1827 long v;
1828 do {
1829 v = getLongVolatile(o, offset);
1830 } while (!compareAndSwapLong(o, offset, v, newValue));
1831 return v;
1832 }
1833
1834 /**
1835 * Atomically exchanges the given reference value with the current
1836 * reference value of a field or array element within the given
1837 * object {@code o} at the given {@code offset}.
1838 *
1839 * @param o object/array to update the field/element in
1840 * @param offset field/element offset
1841 * @param newValue new value
1842 * @return the previous value
1843 * @since 1.8
1844 */
1845 @HotSpotIntrinsicCandidate
1846 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1847 Object v;
1848 do {
1849 v = getObjectVolatile(o, offset);
1850 } while (!compareAndSwapObject(o, offset, v, newValue));
1851 return v;
1852 }
1853
1854
1855 /**
1856 * Ensures that loads before the fence will not be reordered with loads and
1857 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1858 *
1859 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1860 * (an "acquire fence").
1861 *
1862 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1863 * is almost always desired, and most current hardware instructions that
1864 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1865 * @since 1.8
1866 */
1867 @HotSpotIntrinsicCandidate
1868 public native void loadFence();
1869
1870 /**
1871 * Ensures that loads and stores before the fence will not be reordered with
1872 * stores after the fence; a "StoreStore plus LoadStore barrier".
1873 *
1874 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1875 * (a "release fence").
1876 *
1877 * A pure StoreStore fence is not provided, since the addition of LoadStore
1878 * is almost always desired, and most current hardware instructions that
1879 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1880 * @since 1.8
1881 */
1882 @HotSpotIntrinsicCandidate
1883 public native void storeFence();
1884
1885 /**
1886 * Ensures that loads and stores before the fence will not be reordered
1887 * with loads and stores after the fence. Implies the effects of both
1888 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1889 * barrier.
1890 *
1891 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1892 * @since 1.8
1893 */
1894 @HotSpotIntrinsicCandidate
1895 public native void fullFence();
1896
1897 /**
1898 * Ensures that loads before the fence will not be reordered with
1899 * loads after the fence.
1900 */
1901 public final void loadLoadFence() {
1902 loadFence();
1903 }
1904
1905 /**
1906 * Ensures that stores before the fence will not be reordered with
1907 * stores after the fence.
1908 */
1909 public final void storeStoreFence() {
1910 storeFence();
1911 }
1912
1913
1914 /**
1915 * Throws IllegalAccessError; for use by the VM for access control
1916 * error support.
1917 * @since 1.8
1918 */
1919 private static void throwIllegalAccessError() {
1920 throw new IllegalAccessError();
1921 }
1922
1923 /**
1924 * @return Returns true if the native byte ordering of this
1925 * platform is big-endian, false if it is little-endian.
1926 */
1927 public final boolean isBigEndian() { return BE; }
1928
1929 /**
1930 * @return Returns true if this platform is capable of performing
1931 * accesses at addresses which are not aligned for the type of the
1932 * primitive type being accessed, false otherwise.
1933 */
1934 public final boolean unalignedAccess() { return unalignedAccess; }
1935
1936 /**
1937 * Fetches a value at some byte offset into a given Java object.
1938 * More specifically, fetches a value within the given object
1939 * <code>o</code> at the given offset, or (if <code>o</code> is
1940 * null) from the memory address whose numerical value is the
1941 * given offset. <p>
1942 *
1943 * The specification of this method is the same as {@link
1944 * #getLong(Object, long)} except that the offset does not need to
1945 * have been obtained from {@link #objectFieldOffset} on the
1946 * {@link java.lang.reflect.Field} of some Java field. The value
1947 * in memory is raw data, and need not correspond to any Java
1948 * variable. Unless <code>o</code> is null, the value accessed
1949 * must be entirely within the allocated object. The endianness
1950 * of the value in memory is the endianness of the native platform.
1951 *
1952 * <p> The read will be atomic with respect to the largest power
1953 * of two that divides the GCD of the offset and the storage size.
1954 * For example, getLongUnaligned will make atomic reads of 2-, 4-,
1955 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1956 * respectively. There are no other guarantees of atomicity.
1957 * <p>
1958 * 8-byte atomicity is only guaranteed on platforms on which
1959 * support atomic accesses to longs.
1960 *
1961 * @param o Java heap object in which the value resides, if any, else
1962 * null
1963 * @param offset The offset in bytes from the start of the object
1964 * @return the value fetched from the indicated object
1965 * @throws RuntimeException No defined exceptions are thrown, not even
1966 * {@link NullPointerException}
1967 * @since 9
1968 */
1969 @HotSpotIntrinsicCandidate
1970 public final long getLongUnaligned(Object o, long offset) {
1971 if ((offset & 7) == 0) {
1972 return getLong(o, offset);
1973 } else if ((offset & 3) == 0) {
1974 return makeLong(getInt(o, offset),
1975 getInt(o, offset + 4));
1976 } else if ((offset & 1) == 0) {
1977 return makeLong(getShort(o, offset),
1978 getShort(o, offset + 2),
1979 getShort(o, offset + 4),
1980 getShort(o, offset + 6));
1981 } else {
1982 return makeLong(getByte(o, offset),
1983 getByte(o, offset + 1),
1984 getByte(o, offset + 2),
1985 getByte(o, offset + 3),
1986 getByte(o, offset + 4),
1987 getByte(o, offset + 5),
1988 getByte(o, offset + 6),
1989 getByte(o, offset + 7));
1990 }
1991 }
1992 /**
1993 * As {@link #getLongUnaligned(Object, long)} but with an
1994 * additional argument which specifies the endianness of the value
1995 * as stored in memory.
1996 *
1997 * @param o Java heap object in which the variable resides
1998 * @param offset The offset in bytes from the start of the object
1999 * @param bigEndian The endianness of the value
2000 * @return the value fetched from the indicated object
2001 * @since 9
2002 */
2003 public final long getLongUnaligned(Object o, long offset, boolean bigEndian) {
2004 return convEndian(bigEndian, getLongUnaligned(o, offset));
2005 }
2006
2007 /** @see #getLongUnaligned(Object, long) */
2008 @HotSpotIntrinsicCandidate
2009 public final int getIntUnaligned(Object o, long offset) {
2010 if ((offset & 3) == 0) {
2011 return getInt(o, offset);
2012 } else if ((offset & 1) == 0) {
2013 return makeInt(getShort(o, offset),
2014 getShort(o, offset + 2));
2015 } else {
2016 return makeInt(getByte(o, offset),
2017 getByte(o, offset + 1),
2018 getByte(o, offset + 2),
2019 getByte(o, offset + 3));
2020 }
2021 }
2022 /** @see #getLongUnaligned(Object, long, boolean) */
2023 public final int getIntUnaligned(Object o, long offset, boolean bigEndian) {
2024 return convEndian(bigEndian, getIntUnaligned(o, offset));
2025 }
2026
2027 /** @see #getLongUnaligned(Object, long) */
2028 @HotSpotIntrinsicCandidate
2029 public final short getShortUnaligned(Object o, long offset) {
2030 if ((offset & 1) == 0) {
2031 return getShort(o, offset);
2032 } else {
2033 return makeShort(getByte(o, offset),
2034 getByte(o, offset + 1));
2035 }
2036 }
2037 /** @see #getLongUnaligned(Object, long, boolean) */
2038 public final short getShortUnaligned(Object o, long offset, boolean bigEndian) {
2039 return convEndian(bigEndian, getShortUnaligned(o, offset));
2040 }
2041
2042 /** @see #getLongUnaligned(Object, long) */
2043 @HotSpotIntrinsicCandidate
2044 public final char getCharUnaligned(Object o, long offset) {
2045 if ((offset & 1) == 0) {
2046 return getChar(o, offset);
2047 } else {
2048 return (char)makeShort(getByte(o, offset),
2049 getByte(o, offset + 1));
2050 }
2051 }
2052
2053 /** @see #getLongUnaligned(Object, long, boolean) */
2054 public final char getCharUnaligned(Object o, long offset, boolean bigEndian) {
2055 return convEndian(bigEndian, getCharUnaligned(o, offset));
2056 }
2057
2058 /**
2059 * Stores a value at some byte offset into a given Java object.
2060 * <p>
2061 * The specification of this method is the same as {@link
2062 * #getLong(Object, long)} except that the offset does not need to
2063 * have been obtained from {@link #objectFieldOffset} on the
2064 * {@link java.lang.reflect.Field} of some Java field. The value
2065 * in memory is raw data, and need not correspond to any Java
2066 * variable. The endianness of the value in memory is the
2067 * endianness of the native platform.
2068 * <p>
2069 * The write will be atomic with respect to the largest power of
2070 * two that divides the GCD of the offset and the storage size.
2071 * For example, putLongUnaligned will make atomic writes of 2-, 4-,
2072 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
2073 * respectively. There are no other guarantees of atomicity.
2074 * <p>
2075 * 8-byte atomicity is only guaranteed on platforms on which
2076 * support atomic accesses to longs.
2077 *
2078 * @param o Java heap object in which the value resides, if any, else
2079 * null
2080 * @param offset The offset in bytes from the start of the object
2081 * @param x the value to store
2082 * @throws RuntimeException No defined exceptions are thrown, not even
2083 * {@link NullPointerException}
2084 * @since 9
2085 */
2086 @HotSpotIntrinsicCandidate
2087 public final void putLongUnaligned(Object o, long offset, long x) {
2088 if ((offset & 7) == 0) {
2089 putLong(o, offset, x);
2090 } else if ((offset & 3) == 0) {
2091 putLongParts(o, offset,
2092 (int)(x >> 0),
2093 (int)(x >>> 32));
2094 } else if ((offset & 1) == 0) {
2095 putLongParts(o, offset,
2096 (short)(x >>> 0),
2097 (short)(x >>> 16),
2098 (short)(x >>> 32),
2099 (short)(x >>> 48));
2100 } else {
2101 putLongParts(o, offset,
2102 (byte)(x >>> 0),
2103 (byte)(x >>> 8),
2104 (byte)(x >>> 16),
2105 (byte)(x >>> 24),
2106 (byte)(x >>> 32),
2107 (byte)(x >>> 40),
2108 (byte)(x >>> 48),
2109 (byte)(x >>> 56));
2110 }
2111 }
2112
2113 /**
2114 * As {@link #putLongUnaligned(Object, long, long)} but with an additional
2115 * argument which specifies the endianness of the value as stored in memory.
2116 * @param o Java heap object in which the value resides
2117 * @param offset The offset in bytes from the start of the object
2118 * @param x the value to store
2119 * @param bigEndian The endianness of the value
2120 * @throws RuntimeException No defined exceptions are thrown, not even
2121 * {@link NullPointerException}
2122 * @since 9
2123 */
2124 public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) {
2125 putLongUnaligned(o, offset, convEndian(bigEndian, x));
2126 }
2127
2128 /** @see #putLongUnaligned(Object, long, long) */
2129 @HotSpotIntrinsicCandidate
2130 public final void putIntUnaligned(Object o, long offset, int x) {
2131 if ((offset & 3) == 0) {
2132 putInt(o, offset, x);
2133 } else if ((offset & 1) == 0) {
2134 putIntParts(o, offset,
2135 (short)(x >> 0),
2136 (short)(x >>> 16));
2137 } else {
2138 putIntParts(o, offset,
2139 (byte)(x >>> 0),
2140 (byte)(x >>> 8),
2141 (byte)(x >>> 16),
2142 (byte)(x >>> 24));
2143 }
2144 }
2145 /** @see #putLongUnaligned(Object, long, long, boolean) */
2146 public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) {
2147 putIntUnaligned(o, offset, convEndian(bigEndian, x));
2148 }
2149
2150 /** @see #putLongUnaligned(Object, long, long) */
2151 @HotSpotIntrinsicCandidate
2152 public final void putShortUnaligned(Object o, long offset, short x) {
2153 if ((offset & 1) == 0) {
2154 putShort(o, offset, x);
2155 } else {
2156 putShortParts(o, offset,
2157 (byte)(x >>> 0),
2158 (byte)(x >>> 8));
2159 }
2160 }
2161 /** @see #putLongUnaligned(Object, long, long, boolean) */
2162 public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) {
2163 putShortUnaligned(o, offset, convEndian(bigEndian, x));
2164 }
2165
2166 /** @see #putLongUnaligned(Object, long, long) */
2167 @HotSpotIntrinsicCandidate
2168 public final void putCharUnaligned(Object o, long offset, char x) {
2169 putShortUnaligned(o, offset, (short)x);
2170 }
2171 /** @see #putLongUnaligned(Object, long, long, boolean) */
2172 public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) {
2173 putCharUnaligned(o, offset, convEndian(bigEndian, x));
2174 }
2175
2176 // JVM interface methods
2177 // BE is true iff the native endianness of this platform is big.
2178 private static final boolean BE = theUnsafe.isBigEndian0();
2179
2180 // unalignedAccess is true iff this platform can perform unaligned accesses.
2181 private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
2182
2183 private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
2184
2185 // These methods construct integers from bytes. The byte ordering
2186 // is the native endianness of this platform.
2187 private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
2188 return ((toUnsignedLong(i0) << pickPos(56, 0))
2189 | (toUnsignedLong(i1) << pickPos(56, 8))
2190 | (toUnsignedLong(i2) << pickPos(56, 16))
2191 | (toUnsignedLong(i3) << pickPos(56, 24))
2192 | (toUnsignedLong(i4) << pickPos(56, 32))
2193 | (toUnsignedLong(i5) << pickPos(56, 40))
2194 | (toUnsignedLong(i6) << pickPos(56, 48))
2195 | (toUnsignedLong(i7) << pickPos(56, 56)));
2196 }
2197 private static long makeLong(short i0, short i1, short i2, short i3) {
2198 return ((toUnsignedLong(i0) << pickPos(48, 0))
2199 | (toUnsignedLong(i1) << pickPos(48, 16))
2200 | (toUnsignedLong(i2) << pickPos(48, 32))
2201 | (toUnsignedLong(i3) << pickPos(48, 48)));
2202 }
2203 private static long makeLong(int i0, int i1) {
2204 return (toUnsignedLong(i0) << pickPos(32, 0))
2205 | (toUnsignedLong(i1) << pickPos(32, 32));
2206 }
2207 private static int makeInt(short i0, short i1) {
2208 return (toUnsignedInt(i0) << pickPos(16, 0))
2209 | (toUnsignedInt(i1) << pickPos(16, 16));
2210 }
2211 private static int makeInt(byte i0, byte i1, byte i2, byte i3) {
2212 return ((toUnsignedInt(i0) << pickPos(24, 0))
2213 | (toUnsignedInt(i1) << pickPos(24, 8))
2214 | (toUnsignedInt(i2) << pickPos(24, 16))
2215 | (toUnsignedInt(i3) << pickPos(24, 24)));
2216 }
2217 private static short makeShort(byte i0, byte i1) {
2218 return (short)((toUnsignedInt(i0) << pickPos(8, 0))
2219 | (toUnsignedInt(i1) << pickPos(8, 8)));
2220 }
2221
2222 private static byte pick(byte le, byte be) { return BE ? be : le; }
2223 private static short pick(short le, short be) { return BE ? be : le; }
2224 private static int pick(int le, int be) { return BE ? be : le; }
2225
2226 // These methods write integers to memory from smaller parts
2227 // provided by their caller. The ordering in which these parts
2228 // are written is the native endianness of this platform.
2229 private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
2230 putByte(o, offset + 0, pick(i0, i7));
2231 putByte(o, offset + 1, pick(i1, i6));
2232 putByte(o, offset + 2, pick(i2, i5));
2233 putByte(o, offset + 3, pick(i3, i4));
2234 putByte(o, offset + 4, pick(i4, i3));
2235 putByte(o, offset + 5, pick(i5, i2));
2236 putByte(o, offset + 6, pick(i6, i1));
2237 putByte(o, offset + 7, pick(i7, i0));
2238 }
2239 private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) {
2240 putShort(o, offset + 0, pick(i0, i3));
2241 putShort(o, offset + 2, pick(i1, i2));
2242 putShort(o, offset + 4, pick(i2, i1));
2243 putShort(o, offset + 6, pick(i3, i0));
2244 }
2245 private void putLongParts(Object o, long offset, int i0, int i1) {
2246 putInt(o, offset + 0, pick(i0, i1));
2247 putInt(o, offset + 4, pick(i1, i0));
2248 }
2249 private void putIntParts(Object o, long offset, short i0, short i1) {
2250 putShort(o, offset + 0, pick(i0, i1));
2251 putShort(o, offset + 2, pick(i1, i0));
2252 }
2253 private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) {
2254 putByte(o, offset + 0, pick(i0, i3));
2255 putByte(o, offset + 1, pick(i1, i2));
2256 putByte(o, offset + 2, pick(i2, i1));
2257 putByte(o, offset + 3, pick(i3, i0));
2258 }
2259 private void putShortParts(Object o, long offset, byte i0, byte i1) {
2260 putByte(o, offset + 0, pick(i0, i1));
2261 putByte(o, offset + 1, pick(i1, i0));
2262 }
2263
2264 // Zero-extend an integer
2265 private static int toUnsignedInt(byte n) { return n & 0xff; }
2266 private static int toUnsignedInt(short n) { return n & 0xffff; }
2267 private static long toUnsignedLong(byte n) { return n & 0xffl; }
2268 private static long toUnsignedLong(short n) { return n & 0xffffl; }
2269 private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
2270
2271 // Maybe byte-reverse an integer
2272 private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
2273 private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
2274 private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
2275 private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
2276
2277
2278
2279 private native long allocateMemory0(long bytes);
2280 private native long reallocateMemory0(long address, long bytes);
2281 private native void freeMemory0(long address);
2282 private native void setMemory0(Object o, long offset, long bytes, byte value);
2283 @HotSpotIntrinsicCandidate
2284 private native void copyMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes);
2285 private native void copySwapMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes, long elemSize);
2286 private native long objectFieldOffset0(Field f);
2287 private native long staticFieldOffset0(Field f);
2288 private native Object staticFieldBase0(Field f);
2289 private native boolean shouldBeInitialized0(Class<?> c);
2290 private native void ensureClassInitialized0(Class<?> c);
2291 private native int arrayBaseOffset0(Class<?> arrayClass);
2292 private native int arrayIndexScale0(Class<?> arrayClass);
2293 private native int addressSize0();
2294 private native Class<?> defineAnonymousClass0(Class<?> hostClass, byte[] data, Object[] cpPatches);
2295 private native int getLoadAverage0(double[] loadavg, int nelems);
2296 private native boolean unalignedAccess0();
2297 private native boolean isBigEndian0();
2298 }