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 jdk.internal.HotSpotIntrinsicCandidate;
29 import jdk.internal.vm.annotation.ForceInline;
30
31 import java.lang.reflect.Field;
32 import java.security.ProtectionDomain;
33
34
35 /**
36 * A collection of methods for performing low-level, unsafe operations.
37 * Although the class and all methods are public, use of this class is
38 * limited because only trusted code can obtain instances of it.
39 *
40 * <em>Note:</em> It is the resposibility of the caller to make sure
41 * arguments are checked before methods of this class are
42 * called. While some rudimentary checks are performed on the input,
43 * the checks are best effort and when performance is an overriding
44 * priority, as when methods of this class are optimized by the
45 * runtime compiler, some or all checks (if any) may be elided. Hence,
46 * the caller must not rely on the checks and corresponding
47 * exceptions!
48 *
49 * @author John R. Rose
50 * @see #getUnsafe
51 */
52
53 public final class Unsafe {
54
55 private static native void registerNatives();
56 static {
57 registerNatives();
58 }
59
60 private Unsafe() {}
61
62 private static final Unsafe theUnsafe = new Unsafe();
63
64 /**
65 * Provides the caller with the capability of performing unsafe
66 * operations.
67 *
68 * <p>The returned {@code Unsafe} object should be carefully guarded
69 * by the caller, since it can be used to read and write data at arbitrary
70 * memory addresses. It must never be passed to untrusted code.
71 *
72 * <p>Most methods in this class are very low-level, and correspond to a
73 * small number of hardware instructions (on typical machines). Compilers
74 * are encouraged to optimize these methods accordingly.
75 *
76 * <p>Here is a suggested idiom for using unsafe operations:
77 *
78 * <pre> {@code
79 * class MyTrustedClass {
80 * private static final Unsafe unsafe = Unsafe.getUnsafe();
81 * ...
82 * private long myCountAddress = ...;
83 * public int getCount() { return unsafe.getByte(myCountAddress); }
84 * }}</pre>
85 *
86 * (It may assist compilers to make the local variable {@code final}.)
87 */
88 public static Unsafe getUnsafe() {
89 return theUnsafe;
90 }
91
92 /// peek and poke operations
93 /// (compilers should optimize these to memory ops)
94
95 // These work on object fields in the Java heap.
96 // They will not work on elements of packed arrays.
97
98 /**
99 * Fetches a value from a given Java variable.
100 * More specifically, fetches a field or array element within the given
101 * object {@code o} at the given offset, or (if {@code o} is null)
102 * from the memory address whose numerical value is the given offset.
103 * <p>
104 * The results are undefined unless one of the following cases is true:
105 * <ul>
106 * <li>The offset was obtained from {@link #objectFieldOffset} on
107 * the {@link java.lang.reflect.Field} of some Java field and the object
108 * referred to by {@code o} is of a class compatible with that
109 * field's class.
110 *
111 * <li>The offset and object reference {@code o} (either null or
112 * non-null) were both obtained via {@link #staticFieldOffset}
113 * and {@link #staticFieldBase} (respectively) from the
114 * reflective {@link Field} representation of some Java field.
115 *
116 * <li>The object referred to by {@code o} is an array, and the offset
117 * is an integer of the form {@code B+N*S}, where {@code N} is
118 * a valid index into the array, and {@code B} and {@code S} are
119 * the values obtained by {@link #arrayBaseOffset} and {@link
120 * #arrayIndexScale} (respectively) from the array's class. The value
121 * referred to is the {@code N}<em>th</em> element of the array.
122 *
123 * </ul>
124 * <p>
125 * If one of the above cases is true, the call references a specific Java
126 * variable (field or array element). However, the results are undefined
127 * if that variable is not in fact of the type returned by this method.
128 * <p>
129 * This method refers to a variable by means of two parameters, and so
130 * it provides (in effect) a <em>double-register</em> addressing mode
131 * for Java variables. When the object reference is null, this method
132 * uses its offset as an absolute address. This is similar in operation
133 * to methods such as {@link #getInt(long)}, which provide (in effect) a
134 * <em>single-register</em> addressing mode for non-Java variables.
135 * However, because Java variables may have a different layout in memory
136 * from non-Java variables, programmers should not assume that these
137 * two addressing modes are ever equivalent. Also, programmers should
138 * remember that offsets from the double-register addressing mode cannot
139 * be portably confused with longs used in the single-register addressing
140 * mode.
141 *
142 * @param o Java heap object in which the variable resides, if any, else
143 * null
144 * @param offset indication of where the variable resides in a Java heap
145 * object, if any, else a memory address locating the variable
146 * statically
147 * @return the value fetched from the indicated Java variable
148 * @throws RuntimeException No defined exceptions are thrown, not even
149 * {@link NullPointerException}
150 */
151 @HotSpotIntrinsicCandidate
152 public native int getInt(Object o, long offset);
153
154 /**
155 * Stores a value into a given Java variable.
156 * <p>
157 * The first two parameters are interpreted exactly as with
158 * {@link #getInt(Object, long)} to refer to a specific
159 * Java variable (field or array element). The given value
160 * is stored into that variable.
161 * <p>
162 * The variable must be of the same type as the method
163 * parameter {@code x}.
164 *
165 * @param o Java heap object in which the variable resides, if any, else
166 * null
167 * @param offset indication of where the variable resides in a Java heap
168 * object, if any, else a memory address locating the variable
169 * statically
170 * @param x the value to store into the indicated Java variable
171 * @throws RuntimeException No defined exceptions are thrown, not even
172 * {@link NullPointerException}
173 */
174 @HotSpotIntrinsicCandidate
175 public native void putInt(Object o, long offset, int x);
176
177 /**
178 * Fetches a reference value from a given Java variable.
179 * @see #getInt(Object, long)
180 */
181 @HotSpotIntrinsicCandidate
182 public native Object getObject(Object o, long offset);
183
184 /**
185 * Stores a reference value into a given Java variable.
186 * <p>
187 * Unless the reference {@code x} being stored is either null
188 * or matches the field type, the results are undefined.
189 * If the reference {@code o} is non-null, card marks or
190 * other store barriers for that object (if the VM requires them)
191 * are updated.
192 * @see #putInt(Object, long, int)
193 */
194 @HotSpotIntrinsicCandidate
195 public native void putObject(Object o, long offset, Object x);
196
197 /** @see #getInt(Object, long) */
198 @HotSpotIntrinsicCandidate
199 public native boolean getBoolean(Object o, long offset);
200
201 /** @see #putInt(Object, long, int) */
202 @HotSpotIntrinsicCandidate
203 public native void putBoolean(Object o, long offset, boolean x);
204
205 /** @see #getInt(Object, long) */
206 @HotSpotIntrinsicCandidate
207 public native byte getByte(Object o, long offset);
208
209 /** @see #putInt(Object, long, int) */
210 @HotSpotIntrinsicCandidate
211 public native void putByte(Object o, long offset, byte x);
212
213 /** @see #getInt(Object, long) */
214 @HotSpotIntrinsicCandidate
215 public native short getShort(Object o, long offset);
216
217 /** @see #putInt(Object, long, int) */
218 @HotSpotIntrinsicCandidate
219 public native void putShort(Object o, long offset, short x);
220
221 /** @see #getInt(Object, long) */
222 @HotSpotIntrinsicCandidate
223 public native char getChar(Object o, long offset);
224
225 /** @see #putInt(Object, long, int) */
226 @HotSpotIntrinsicCandidate
227 public native void putChar(Object o, long offset, char x);
228
229 /** @see #getInt(Object, long) */
230 @HotSpotIntrinsicCandidate
231 public native long getLong(Object o, long offset);
232
233 /** @see #putInt(Object, long, int) */
234 @HotSpotIntrinsicCandidate
235 public native void putLong(Object o, long offset, long x);
236
237 /** @see #getInt(Object, long) */
238 @HotSpotIntrinsicCandidate
239 public native float getFloat(Object o, long offset);
240
241 /** @see #putInt(Object, long, int) */
242 @HotSpotIntrinsicCandidate
243 public native void putFloat(Object o, long offset, float x);
244
245 /** @see #getInt(Object, long) */
246 @HotSpotIntrinsicCandidate
247 public native double getDouble(Object o, long offset);
248
249 /** @see #putInt(Object, long, int) */
250 @HotSpotIntrinsicCandidate
251 public native void putDouble(Object o, long offset, double x);
252
253 /**
254 * Fetches a native pointer from a given memory address. If the address is
255 * zero, or does not point into a block obtained from {@link
256 * #allocateMemory}, the results are undefined.
257 *
258 * <p>If the native pointer is less than 64 bits wide, it is extended as
259 * an unsigned number to a Java long. The pointer may be indexed by any
260 * given byte offset, simply by adding that offset (as a simple integer) to
261 * the long representing the pointer. The number of bytes actually read
262 * from the target address may be determined by consulting {@link
263 * #addressSize}.
264 *
265 * @see #allocateMemory
266 * @see #getInt(Object, long)
267 */
268 @ForceInline
269 public long getAddress(Object o, long offset) {
270 if (ADDRESS_SIZE == 4) {
271 return Integer.toUnsignedLong(getInt(o, offset));
272 } else {
273 return getLong(o, offset);
274 }
275 }
276
277 /**
278 * Stores a native pointer into a given memory address. If the address is
279 * zero, or does not point into a block obtained from {@link
280 * #allocateMemory}, the results are undefined.
281 *
282 * <p>The number of bytes actually written at the target address may be
283 * determined by consulting {@link #addressSize}.
284 *
285 * @see #allocateMemory
286 * @see #putInt(Object, long, int)
287 */
288 @ForceInline
289 public void putAddress(Object o, long offset, long x) {
290 if (ADDRESS_SIZE == 4) {
291 putInt(o, offset, (int)x);
292 } else {
293 putLong(o, offset, x);
294 }
295 }
296
297 // These read VM internal data.
298
299 /**
300 * Fetches an uncompressed reference value from a given native variable
301 * ignoring the VM's compressed references mode.
302 *
303 * @param address a memory address locating the variable
304 * @return the value fetched from the indicated native variable
305 */
306 public native Object getUncompressedObject(long address);
307
308 // These work on values in the C heap.
309
310 /**
311 * Fetches a value from a given memory address. If the address is zero, or
312 * does not point into a block obtained from {@link #allocateMemory}, the
313 * results are undefined.
314 *
315 * @see #allocateMemory
316 */
317 @ForceInline
318 public byte getByte(long address) {
319 return getByte(null, address);
320 }
321
322 /**
323 * Stores a value into a given memory address. If the address is zero, or
324 * does not point into a block obtained from {@link #allocateMemory}, the
325 * results are undefined.
326 *
327 * @see #getByte(long)
328 */
329 @ForceInline
330 public void putByte(long address, byte x) {
331 putByte(null, address, x);
332 }
333
334 /** @see #getByte(long) */
335 @ForceInline
336 public short getShort(long address) {
337 return getShort(null, address);
338 }
339
340 /** @see #putByte(long, byte) */
341 @ForceInline
342 public void putShort(long address, short x) {
343 putShort(null, address, x);
344 }
345
346 /** @see #getByte(long) */
347 @ForceInline
348 public char getChar(long address) {
349 return getChar(null, address);
350 }
351
352 /** @see #putByte(long, byte) */
353 @ForceInline
354 public void putChar(long address, char x) {
355 putChar(null, address, x);
356 }
357
358 /** @see #getByte(long) */
359 @ForceInline
360 public int getInt(long address) {
361 return getInt(null, address);
362 }
363
364 /** @see #putByte(long, byte) */
365 @ForceInline
366 public void putInt(long address, int x) {
367 putInt(null, address, x);
368 }
369
370 /** @see #getByte(long) */
371 @ForceInline
372 public long getLong(long address) {
373 return getLong(null, address);
374 }
375
376 /** @see #putByte(long, byte) */
377 @ForceInline
378 public void putLong(long address, long x) {
379 putLong(null, address, x);
380 }
381
382 /** @see #getByte(long) */
383 @ForceInline
384 public float getFloat(long address) {
385 return getFloat(null, address);
386 }
387
388 /** @see #putByte(long, byte) */
389 @ForceInline
390 public void putFloat(long address, float x) {
391 putFloat(null, address, x);
392 }
393
394 /** @see #getByte(long) */
395 @ForceInline
396 public double getDouble(long address) {
397 return getDouble(null, address);
398 }
399
400 /** @see #putByte(long, byte) */
401 @ForceInline
402 public void putDouble(long address, double x) {
403 putDouble(null, address, x);
404 }
405
406 /** @see #getAddress(Object, long) */
407 @ForceInline
408 public long getAddress(long address) {
409 return getAddress(null, address);
410 }
411
412 /** @see #putAddress(Object, long, long) */
413 @ForceInline
414 public void putAddress(long address, long x) {
415 putAddress(null, address, x);
416 }
417
418
419
420 /// helper methods for validating various types of objects/values
421
422 /**
423 * Create an exception reflecting that some of the input was invalid
424 *
425 * <em>Note:</em> It is the resposibility of the caller to make
426 * sure arguments are checked before the methods are called. While
427 * some rudimentary checks are performed on the input, the checks
428 * are best effort and when performance is an overriding priority,
429 * as when methods of this class are optimized by the runtime
430 * compiler, some or all checks (if any) may be elided. Hence, the
431 * caller must not rely on the checks and corresponding
432 * exceptions!
433 *
434 * @return an exception object
435 */
436 private RuntimeException invalidInput() {
437 return new IllegalArgumentException();
438 }
439
440 /**
441 * Check if a value is 32-bit clean (32 MSB are all zero)
442 *
443 * @param value the 64-bit value to check
444 *
445 * @return true if the value is 32-bit clean
446 */
447 private boolean is32BitClean(long value) {
448 return value >>> 32 == 0;
449 }
450
451 /**
452 * Check the validity of a size (the equivalent of a size_t)
453 *
454 * @throws RuntimeException if the size is invalid
455 * (<em>Note:</em> after optimization, invalid inputs may
456 * go undetected, which will lead to unpredictable
457 * behavior)
458 */
459 private void checkSize(long size) {
460 if (ADDRESS_SIZE == 4) {
461 // Note: this will also check for negative sizes
462 if (!is32BitClean(size)) {
463 throw invalidInput();
464 }
465 } else if (size < 0) {
466 throw invalidInput();
467 }
468 }
469
470 /**
471 * Check the validity of a native address (the equivalent of void*)
472 *
473 * @throws RuntimeException if the address is invalid
474 * (<em>Note:</em> after optimization, invalid inputs may
475 * go undetected, which will lead to unpredictable
476 * behavior)
477 */
478 private void checkNativeAddress(long address) {
479 if (ADDRESS_SIZE == 4) {
480 // Accept both zero and sign extended pointers. A valid
481 // pointer will, after the +1 below, either have produced
482 // the value 0x0 or 0x1. Masking off the low bit allows
483 // for testing against 0.
484 if ((((address >> 32) + 1) & ~1) != 0) {
485 throw invalidInput();
486 }
487 }
488 }
489
490 /**
491 * Check the validity of an offset, relative to a base object
492 *
493 * @param o the base object
494 * @param offset the offset to check
495 *
496 * @throws RuntimeException if the size is invalid
497 * (<em>Note:</em> after optimization, invalid inputs may
498 * go undetected, which will lead to unpredictable
499 * behavior)
500 */
501 private void checkOffset(Object o, long offset) {
502 if (ADDRESS_SIZE == 4) {
503 // Note: this will also check for negative offsets
504 if (!is32BitClean(offset)) {
505 throw invalidInput();
506 }
507 } else if (offset < 0) {
508 throw invalidInput();
509 }
510 }
511
512 /**
513 * Check the validity of a double-register pointer
514 *
515 * Note: This code deliberately does *not* check for NPE for (at
516 * least) three reasons:
517 *
518 * 1) NPE is not just NULL/0 - there is a range of values all
519 * resulting in an NPE, which is not trivial to check for
520 *
521 * 2) It is the responsibility of the callers of Unsafe methods
522 * to verify the input, so throwing an exception here is not really
523 * useful - passing in a NULL pointer is a critical error and the
524 * must not expect an exception to be thrown anyway.
525 *
526 * 3) the actual operations will detect NULL pointers anyway by
527 * means of traps and signals (like SIGSEGV).
528 *
529 * @param o Java heap object, or null
530 * @param offset indication of where the variable resides in a Java heap
531 * object, if any, else a memory address locating the variable
532 * statically
533 *
534 * @throws RuntimeException if the pointer is invalid
535 * (<em>Note:</em> after optimization, invalid inputs may
536 * go undetected, which will lead to unpredictable
537 * behavior)
538 */
539 private void checkPointer(Object o, long offset) {
540 if (o == null) {
541 checkNativeAddress(offset);
542 } else {
543 checkOffset(o, offset);
544 }
545 }
546
547 /**
548 * Check if a type is a primitive array type
549 *
550 * @param c the type to check
551 *
552 * @return true if the type is a primitive array type
553 */
554 private void checkPrimitiveArray(Class<?> c) {
555 Class<?> componentType = c.getComponentType();
556 if (componentType == null || !componentType.isPrimitive()) {
557 throw invalidInput();
558 }
559 }
560
561 /**
562 * Check that a pointer is a valid primitive array type pointer
563 *
564 * Note: pointers off-heap are considered to be primitive arrays
565 *
566 * @throws RuntimeException if the pointer is invalid
567 * (<em>Note:</em> after optimization, invalid inputs may
568 * go undetected, which will lead to unpredictable
569 * behavior)
570 */
571 private void checkPrimitivePointer(Object o, long offset) {
572 checkPointer(o, offset);
573
574 if (o != null) {
575 // If on heap, it it must be a primitive array
576 checkPrimitiveArray(o.getClass());
577 }
578 }
579
580
581 /// wrappers for malloc, realloc, free:
582
583 /**
584 * Allocates a new block of native memory, of the given size in bytes. The
585 * contents of the memory are uninitialized; they will generally be
586 * garbage. The resulting native pointer will never be zero, and will be
587 * aligned for all value types. Dispose of this memory by calling {@link
588 * #freeMemory}, or resize it with {@link #reallocateMemory}.
589 *
590 * <em>Note:</em> It is the resposibility of the caller to make
591 * sure arguments are checked before the methods are called. While
592 * some rudimentary checks are performed on the input, the checks
593 * are best effort and when performance is an overriding priority,
594 * as when methods of this class are optimized by the runtime
595 * compiler, some or all checks (if any) may be elided. Hence, the
596 * caller must not rely on the checks and corresponding
597 * exceptions!
598 *
599 * @throws RuntimeException if the size is negative or too large
600 * for the native size_t type
601 *
602 * @throws OutOfMemoryError if the allocation is refused by the system
603 *
604 * @see #getByte(long)
605 * @see #putByte(long, byte)
606 */
607 public long allocateMemory(long bytes) {
608 allocateMemoryChecks(bytes);
609
610 if (bytes == 0) {
611 return 0;
612 }
613
614 long p = allocateMemory0(bytes);
615 if (p == 0) {
616 throw new OutOfMemoryError();
617 }
618
619 return p;
620 }
621
622 /**
623 * Validate the arguments to allocateMemory
624 *
625 * @throws RuntimeException if the arguments are invalid
626 * (<em>Note:</em> after optimization, invalid inputs may
627 * go undetected, which will lead to unpredictable
628 * behavior)
629 */
630 private void allocateMemoryChecks(long bytes) {
631 checkSize(bytes);
632 }
633
634 /**
635 * Resizes a new block of native memory, to the given size in bytes. The
636 * contents of the new block past the size of the old block are
637 * uninitialized; they will generally be garbage. The resulting native
638 * pointer will be zero if and only if the requested size is zero. The
639 * resulting native pointer will be aligned for all value types. Dispose
640 * of this memory by calling {@link #freeMemory}, or resize it with {@link
641 * #reallocateMemory}. The address passed to this method may be null, in
642 * which case an allocation will be performed.
643 *
644 * <em>Note:</em> It is the resposibility of the caller to make
645 * sure arguments are checked before the methods are called. While
646 * some rudimentary checks are performed on the input, the checks
647 * are best effort and when performance is an overriding priority,
648 * as when methods of this class are optimized by the runtime
649 * compiler, some or all checks (if any) may be elided. Hence, the
650 * caller must not rely on the checks and corresponding
651 * exceptions!
652 *
653 * @throws RuntimeException if the size is negative or too large
654 * for the native size_t type
655 *
656 * @throws OutOfMemoryError if the allocation is refused by the system
657 *
658 * @see #allocateMemory
659 */
660 public long reallocateMemory(long address, long bytes) {
661 reallocateMemoryChecks(address, bytes);
662
663 if (bytes == 0) {
664 freeMemory(address);
665 return 0;
666 }
667
668 long p = (address == 0) ? allocateMemory0(bytes) : reallocateMemory0(address, bytes);
669 if (p == 0) {
670 throw new OutOfMemoryError();
671 }
672
673 return p;
674 }
675
676 /**
677 * Validate the arguments to reallocateMemory
678 *
679 * @throws RuntimeException if the arguments are invalid
680 * (<em>Note:</em> after optimization, invalid inputs may
681 * go undetected, which will lead to unpredictable
682 * behavior)
683 */
684 private void reallocateMemoryChecks(long address, long bytes) {
685 checkPointer(null, address);
686 checkSize(bytes);
687 }
688
689 /**
690 * Sets all bytes in a given block of memory to a fixed value
691 * (usually zero).
692 *
693 * <p>This method determines a block's base address by means of two parameters,
694 * and so it provides (in effect) a <em>double-register</em> addressing mode,
695 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
696 * the offset supplies an absolute base address.
697 *
698 * <p>The stores are in coherent (atomic) units of a size determined
699 * by the address and length parameters. If the effective address and
700 * length are all even modulo 8, the stores take place in 'long' units.
701 * If the effective address and length are (resp.) even modulo 4 or 2,
702 * the stores take place in units of 'int' or 'short'.
703 *
704 * <em>Note:</em> It is the resposibility of the caller to make
705 * sure arguments are checked before the methods are called. While
706 * some rudimentary checks are performed on the input, the checks
707 * are best effort and when performance is an overriding priority,
708 * as when methods of this class are optimized by the runtime
709 * compiler, some or all checks (if any) may be elided. Hence, the
710 * caller must not rely on the checks and corresponding
711 * exceptions!
712 *
713 * @throws RuntimeException if any of the arguments is invalid
714 *
715 * @since 1.7
716 */
717 public void setMemory(Object o, long offset, long bytes, byte value) {
718 setMemoryChecks(o, offset, bytes, value);
719
720 if (bytes == 0) {
721 return;
722 }
723
724 setMemory0(o, offset, bytes, value);
725 }
726
727 /**
728 * Sets all bytes in a given block of memory to a fixed value
729 * (usually zero). This provides a <em>single-register</em> addressing mode,
730 * as discussed in {@link #getInt(Object,long)}.
731 *
732 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
733 */
734 public void setMemory(long address, long bytes, byte value) {
735 setMemory(null, address, bytes, value);
736 }
737
738 /**
739 * Validate the arguments to setMemory
740 *
741 * @throws RuntimeException if the arguments are invalid
742 * (<em>Note:</em> after optimization, invalid inputs may
743 * go undetected, which will lead to unpredictable
744 * behavior)
745 */
746 private void setMemoryChecks(Object o, long offset, long bytes, byte value) {
747 checkPrimitivePointer(o, offset);
748 checkSize(bytes);
749 }
750
751 /**
752 * Sets all bytes in a given block of memory to a copy of another
753 * block.
754 *
755 * <p>This method determines each block's base address by means of two parameters,
756 * and so it provides (in effect) a <em>double-register</em> addressing mode,
757 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
758 * the offset supplies an absolute base address.
759 *
760 * <p>The transfers are in coherent (atomic) units of a size determined
761 * by the address and length parameters. If the effective addresses and
762 * length are all even modulo 8, the transfer takes place in 'long' units.
763 * If the effective addresses and length are (resp.) even modulo 4 or 2,
764 * the transfer takes place in units of 'int' or 'short'.
765 *
766 * <em>Note:</em> It is the resposibility of the caller to make
767 * sure arguments are checked before the methods are called. While
768 * some rudimentary checks are performed on the input, the checks
769 * are best effort and when performance is an overriding priority,
770 * as when methods of this class are optimized by the runtime
771 * compiler, some or all checks (if any) may be elided. Hence, the
772 * caller must not rely on the checks and corresponding
773 * exceptions!
774 *
775 * @throws RuntimeException if any of the arguments is invalid
776 *
777 * @since 1.7
778 */
779 public void copyMemory(Object srcBase, long srcOffset,
780 Object destBase, long destOffset,
781 long bytes) {
782 copyMemoryChecks(srcBase, srcOffset, destBase, destOffset, bytes);
783
784 if (bytes == 0) {
785 return;
786 }
787
788 copyMemory0(srcBase, srcOffset, destBase, destOffset, bytes);
789 }
790
791 /**
792 * Sets all bytes in a given block of memory to a copy of another
793 * block. This provides a <em>single-register</em> addressing mode,
794 * as discussed in {@link #getInt(Object,long)}.
795 *
796 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
797 */
798 public void copyMemory(long srcAddress, long destAddress, long bytes) {
799 copyMemory(null, srcAddress, null, destAddress, bytes);
800 }
801
802 /**
803 * Validate the arguments to copyMemory
804 *
805 * @throws RuntimeException if any of the arguments is invalid
806 * (<em>Note:</em> after optimization, invalid inputs may
807 * go undetected, which will lead to unpredictable
808 * behavior)
809 */
810 private void copyMemoryChecks(Object srcBase, long srcOffset,
811 Object destBase, long destOffset,
812 long bytes) {
813 checkSize(bytes);
814 checkPrimitivePointer(srcBase, srcOffset);
815 checkPrimitivePointer(destBase, destOffset);
816 }
817
818 /**
819 * Copies all elements from one block of memory to another block,
820 * *unconditionally* byte swapping the elements on the fly.
821 *
822 * <p>This method determines each block's base address by means of two parameters,
823 * and so it provides (in effect) a <em>double-register</em> addressing mode,
824 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
825 * the offset supplies an absolute base address.
826 *
827 * <em>Note:</em> It is the resposibility of the caller to make
828 * sure arguments are checked before the methods are called. While
829 * some rudimentary checks are performed on the input, the checks
830 * are best effort and when performance is an overriding priority,
831 * as when methods of this class are optimized by the runtime
832 * compiler, some or all checks (if any) may be elided. Hence, the
833 * caller must not rely on the checks and corresponding
834 * exceptions!
835 *
836 * @throws RuntimeException if any of the arguments is invalid
837 *
838 * @since 9
839 */
840 public void copySwapMemory(Object srcBase, long srcOffset,
841 Object destBase, long destOffset,
842 long bytes, long elemSize) {
843 copySwapMemoryChecks(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
844
845 if (bytes == 0) {
846 return;
847 }
848
849 copySwapMemory0(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
850 }
851
852 private void copySwapMemoryChecks(Object srcBase, long srcOffset,
853 Object destBase, long destOffset,
854 long bytes, long elemSize) {
855 checkSize(bytes);
856
857 if (elemSize != 2 && elemSize != 4 && elemSize != 8) {
858 throw invalidInput();
859 }
860 if (bytes % elemSize != 0) {
861 throw invalidInput();
862 }
863
864 checkPrimitivePointer(srcBase, srcOffset);
865 checkPrimitivePointer(destBase, destOffset);
866 }
867
868 /**
869 * Copies all elements from one block of memory to another block, byte swapping the
870 * elements on the fly.
871 *
872 * This provides a <em>single-register</em> addressing mode, as
873 * discussed in {@link #getInt(Object,long)}.
874 *
875 * Equivalent to {@code copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize)}.
876 */
877 public void copySwapMemory(long srcAddress, long destAddress, long bytes, long elemSize) {
878 copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize);
879 }
880
881 /**
882 * Disposes of a block of native memory, as obtained from {@link
883 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
884 * this method may be null, in which case no action is taken.
885 *
886 * <em>Note:</em> It is the resposibility of the caller to make
887 * sure arguments are checked before the methods are called. While
888 * some rudimentary checks are performed on the input, the checks
889 * are best effort and when performance is an overriding priority,
890 * as when methods of this class are optimized by the runtime
891 * compiler, some or all checks (if any) may be elided. Hence, the
892 * caller must not rely on the checks and corresponding
893 * exceptions!
894 *
895 * @throws RuntimeException if any of the arguments is invalid
896 *
897 * @see #allocateMemory
898 */
899 public void freeMemory(long address) {
900 freeMemoryChecks(address);
901
902 if (address == 0) {
903 return;
904 }
905
906 freeMemory0(address);
907 }
908
909 /**
910 * Validate the arguments to freeMemory
911 *
912 * @throws RuntimeException if the arguments are invalid
913 * (<em>Note:</em> after optimization, invalid inputs may
914 * go undetected, which will lead to unpredictable
915 * behavior)
916 */
917 private void freeMemoryChecks(long address) {
918 checkPointer(null, address);
919 }
920
921 /// random queries
922
923 /**
924 * This constant differs from all results that will ever be returned from
925 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
926 * or {@link #arrayBaseOffset}.
927 */
928 public static final int INVALID_FIELD_OFFSET = -1;
929
930 /**
931 * Reports the location of a given field in the storage allocation of its
932 * class. Do not expect to perform any sort of arithmetic on this offset;
933 * it is just a cookie which is passed to the unsafe heap memory accessors.
934 *
935 * <p>Any given field will always have the same offset and base, and no
936 * two distinct fields of the same class will ever have the same offset
937 * and base.
938 *
939 * <p>As of 1.4.1, offsets for fields are represented as long values,
940 * although the Sun JVM does not use the most significant 32 bits.
941 * However, JVM implementations which store static fields at absolute
942 * addresses can use long offsets and null base pointers to express
943 * the field locations in a form usable by {@link #getInt(Object,long)}.
944 * Therefore, code which will be ported to such JVMs on 64-bit platforms
945 * must preserve all bits of static field offsets.
946 * @see #getInt(Object, long)
947 */
948 public long objectFieldOffset(Field f) {
949 if (f == null) {
950 throw new NullPointerException();
951 }
952
953 return objectFieldOffset0(f);
954 }
955
956 /**
957 * Reports the location of a given static field, in conjunction with {@link
958 * #staticFieldBase}.
959 * <p>Do not expect to perform any sort of arithmetic on this offset;
960 * it is just a cookie which is passed to the unsafe heap memory accessors.
961 *
962 * <p>Any given field will always have the same offset, and no two distinct
963 * fields of the same class will ever have the same offset.
964 *
965 * <p>As of 1.4.1, offsets for fields are represented as long values,
966 * although the Sun JVM does not use the most significant 32 bits.
967 * It is hard to imagine a JVM technology which needs more than
968 * a few bits to encode an offset within a non-array object,
969 * However, for consistency with other methods in this class,
970 * this method reports its result as a long value.
971 * @see #getInt(Object, long)
972 */
973 public long staticFieldOffset(Field f) {
974 if (f == null) {
975 throw new NullPointerException();
976 }
977
978 return staticFieldOffset0(f);
979 }
980
981 /**
982 * Reports the location of a given static field, in conjunction with {@link
983 * #staticFieldOffset}.
984 * <p>Fetch the base "Object", if any, with which static fields of the
985 * given class can be accessed via methods like {@link #getInt(Object,
986 * long)}. This value may be null. This value may refer to an object
987 * which is a "cookie", not guaranteed to be a real Object, and it should
988 * not be used in any way except as argument to the get and put routines in
989 * this class.
990 */
991 public Object staticFieldBase(Field f) {
992 if (f == null) {
993 throw new NullPointerException();
994 }
995
996 return staticFieldBase0(f);
997 }
998
999 /**
1000 * Detects if the given class may need to be initialized. This is often
1001 * needed in conjunction with obtaining the static field base of a
1002 * class.
1003 * @return false only if a call to {@code ensureClassInitialized} would have no effect
1004 */
1005 public boolean shouldBeInitialized(Class<?> c) {
1006 if (c == null) {
1007 throw new NullPointerException();
1008 }
1009
1010 return shouldBeInitialized0(c);
1011 }
1012
1013 /**
1014 * Ensures the given class has been initialized. This is often
1015 * needed in conjunction with obtaining the static field base of a
1016 * class.
1017 */
1018 public void ensureClassInitialized(Class<?> c) {
1019 if (c == null) {
1020 throw new NullPointerException();
1021 }
1022
1023 ensureClassInitialized0(c);
1024 }
1025
1026 /**
1027 * Reports the offset of the first element in the storage allocation of a
1028 * given array class. If {@link #arrayIndexScale} returns a non-zero value
1029 * for the same class, you may use that scale factor, together with this
1030 * base offset, to form new offsets to access elements of arrays of the
1031 * given class.
1032 *
1033 * @see #getInt(Object, long)
1034 * @see #putInt(Object, long, int)
1035 */
1036 public int arrayBaseOffset(Class<?> arrayClass) {
1037 if (arrayClass == null) {
1038 throw new NullPointerException();
1039 }
1040
1041 return arrayBaseOffset0(arrayClass);
1042 }
1043
1044
1045 /** The value of {@code arrayBaseOffset(boolean[].class)} */
1046 public static final int ARRAY_BOOLEAN_BASE_OFFSET
1047 = theUnsafe.arrayBaseOffset(boolean[].class);
1048
1049 /** The value of {@code arrayBaseOffset(byte[].class)} */
1050 public static final int ARRAY_BYTE_BASE_OFFSET
1051 = theUnsafe.arrayBaseOffset(byte[].class);
1052
1053 /** The value of {@code arrayBaseOffset(short[].class)} */
1054 public static final int ARRAY_SHORT_BASE_OFFSET
1055 = theUnsafe.arrayBaseOffset(short[].class);
1056
1057 /** The value of {@code arrayBaseOffset(char[].class)} */
1058 public static final int ARRAY_CHAR_BASE_OFFSET
1059 = theUnsafe.arrayBaseOffset(char[].class);
1060
1061 /** The value of {@code arrayBaseOffset(int[].class)} */
1062 public static final int ARRAY_INT_BASE_OFFSET
1063 = theUnsafe.arrayBaseOffset(int[].class);
1064
1065 /** The value of {@code arrayBaseOffset(long[].class)} */
1066 public static final int ARRAY_LONG_BASE_OFFSET
1067 = theUnsafe.arrayBaseOffset(long[].class);
1068
1069 /** The value of {@code arrayBaseOffset(float[].class)} */
1070 public static final int ARRAY_FLOAT_BASE_OFFSET
1071 = theUnsafe.arrayBaseOffset(float[].class);
1072
1073 /** The value of {@code arrayBaseOffset(double[].class)} */
1074 public static final int ARRAY_DOUBLE_BASE_OFFSET
1075 = theUnsafe.arrayBaseOffset(double[].class);
1076
1077 /** The value of {@code arrayBaseOffset(Object[].class)} */
1078 public static final int ARRAY_OBJECT_BASE_OFFSET
1079 = theUnsafe.arrayBaseOffset(Object[].class);
1080
1081 /**
1082 * Reports the scale factor for addressing elements in the storage
1083 * allocation of a given array class. However, arrays of "narrow" types
1084 * will generally not work properly with accessors like {@link
1085 * #getByte(Object, long)}, so the scale factor for such classes is reported
1086 * as zero.
1087 *
1088 * @see #arrayBaseOffset
1089 * @see #getInt(Object, long)
1090 * @see #putInt(Object, long, int)
1091 */
1092 public int arrayIndexScale(Class<?> arrayClass) {
1093 if (arrayClass == null) {
1094 throw new NullPointerException();
1095 }
1096
1097 return arrayIndexScale0(arrayClass);
1098 }
1099
1100
1101 /** The value of {@code arrayIndexScale(boolean[].class)} */
1102 public static final int ARRAY_BOOLEAN_INDEX_SCALE
1103 = theUnsafe.arrayIndexScale(boolean[].class);
1104
1105 /** The value of {@code arrayIndexScale(byte[].class)} */
1106 public static final int ARRAY_BYTE_INDEX_SCALE
1107 = theUnsafe.arrayIndexScale(byte[].class);
1108
1109 /** The value of {@code arrayIndexScale(short[].class)} */
1110 public static final int ARRAY_SHORT_INDEX_SCALE
1111 = theUnsafe.arrayIndexScale(short[].class);
1112
1113 /** The value of {@code arrayIndexScale(char[].class)} */
1114 public static final int ARRAY_CHAR_INDEX_SCALE
1115 = theUnsafe.arrayIndexScale(char[].class);
1116
1117 /** The value of {@code arrayIndexScale(int[].class)} */
1118 public static final int ARRAY_INT_INDEX_SCALE
1119 = theUnsafe.arrayIndexScale(int[].class);
1120
1121 /** The value of {@code arrayIndexScale(long[].class)} */
1122 public static final int ARRAY_LONG_INDEX_SCALE
1123 = theUnsafe.arrayIndexScale(long[].class);
1124
1125 /** The value of {@code arrayIndexScale(float[].class)} */
1126 public static final int ARRAY_FLOAT_INDEX_SCALE
1127 = theUnsafe.arrayIndexScale(float[].class);
1128
1129 /** The value of {@code arrayIndexScale(double[].class)} */
1130 public static final int ARRAY_DOUBLE_INDEX_SCALE
1131 = theUnsafe.arrayIndexScale(double[].class);
1132
1133 /** The value of {@code arrayIndexScale(Object[].class)} */
1134 public static final int ARRAY_OBJECT_INDEX_SCALE
1135 = theUnsafe.arrayIndexScale(Object[].class);
1136
1137 /**
1138 * Reports the size in bytes of a native pointer, as stored via {@link
1139 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
1140 * other primitive types (as stored in native memory blocks) is determined
1141 * fully by their information content.
1142 */
1143 public int addressSize() {
1144 return ADDRESS_SIZE;
1145 }
1146
1147 /** The value of {@code addressSize()} */
1148 public static final int ADDRESS_SIZE = theUnsafe.addressSize0();
1149
1150 /**
1151 * Reports the size in bytes of a native memory page (whatever that is).
1152 * This value will always be a power of two.
1153 */
1154 public native int pageSize();
1155
1156
1157 /// random trusted operations from JNI:
1158
1159 /**
1160 * Tells the VM to define a class, without security checks. By default, the
1161 * class loader and protection domain come from the caller's class.
1162 */
1163 public Class<?> defineClass(String name, byte[] b, int off, int len,
1164 ClassLoader loader,
1165 ProtectionDomain protectionDomain) {
1166 if (b == null) {
1167 throw new NullPointerException();
1168 }
1169 if (len < 0) {
1170 throw new ArrayIndexOutOfBoundsException();
1171 }
1172
1173 return defineClass0(name, b, off, len, loader, protectionDomain);
1174 }
1175
1176 public native Class<?> defineClass0(String name, byte[] b, int off, int len,
1177 ClassLoader loader,
1178 ProtectionDomain protectionDomain);
1179
1180 /**
1181 * Defines a class but does not make it known to the class loader or system dictionary.
1182 * <p>
1183 * For each CP entry, the corresponding CP patch must either be null or have
1184 * the a format that matches its tag:
1185 * <ul>
1186 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
1187 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
1188 * <li>Class: any java.lang.Class object
1189 * <li>String: any object (not just a java.lang.String)
1190 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
1191 * </ul>
1192 * @param hostClass context for linkage, access control, protection domain, and class loader
1193 * @param data bytes of a class file
1194 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
1195 */
1196 public Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches) {
1197 if (hostClass == null || data == null) {
1198 throw new NullPointerException();
1199 }
1200
1201 return defineAnonymousClass0(hostClass, data, cpPatches);
1202 }
1203
1204 /**
1205 * Allocates an instance but does not run any constructor.
1206 * Initializes the class if it has not yet been.
1207 */
1208 @HotSpotIntrinsicCandidate
1209 public native Object allocateInstance(Class<?> cls)
1210 throws InstantiationException;
1211
1212 /**
1213 * Allocates an array of a given type, but does not do zeroing.
1214 * <p>
1215 * This method should only be used in the very rare cases where a high-performance code
1216 * overwrites the destination array completely, and compilers cannot assist in zeroing elimination.
1217 * In an overwhelming majority of cases, a normal Java allocation should be used instead.
1218 * <p>
1219 * Users of this method are <b>required</b> to overwrite the initial (garbage) array contents
1220 * before allowing untrusted code, or code in other threads, to observe the reference
1221 * to the newly allocated array. In addition, the publication of the array reference must be
1222 * safe according to the Java Memory Model requirements.
1223 * <p>
1224 * The safest approach to deal with an uninitialized array is to keep the reference to it in local
1225 * variable at least until the initialization is complete, and then publish it <b>once</b>, either
1226 * by writing it to a <em>volatile</em> field, or storing it into a <em>final</em> field in constructor,
1227 * or issuing a {@link #storeFence} before publishing the reference.
1228 * <p>
1229 * @implnote This method can only allocate primitive arrays, to avoid garbage reference
1230 * elements that could break heap integrity.
1231 *
1232 * @param componentType array component type to allocate
1233 * @param length array size to allocate
1234 * @throws IllegalArgumentException if component type is null, or not a primitive class;
1235 * or the length is negative
1236 */
1237 public Object allocateUninitializedArray(Class<?> componentType, int length) {
1238 if (componentType == null) {
1239 throw new IllegalArgumentException("Component type is null");
1240 }
1241 if (!componentType.isPrimitive()) {
1242 throw new IllegalArgumentException("Component type is not primitive");
1243 }
1244 if (length < 0) {
1245 throw new IllegalArgumentException("Negative length");
1246 }
1247 return allocateUninitializedArray0(componentType, length);
1248 }
1249
1250 @HotSpotIntrinsicCandidate
1251 private Object allocateUninitializedArray0(Class<?> componentType, int length) {
1252 // These fallbacks provide zeroed arrays, but intrinsic is not required to
1253 // return the zeroed arrays.
1254 if (componentType == byte.class) return new byte[length];
1255 if (componentType == boolean.class) return new boolean[length];
1256 if (componentType == short.class) return new short[length];
1257 if (componentType == char.class) return new char[length];
1258 if (componentType == int.class) return new int[length];
1259 if (componentType == float.class) return new float[length];
1260 if (componentType == long.class) return new long[length];
1261 if (componentType == double.class) return new double[length];
1262 return null;
1263 }
1264
1265 /** Throws the exception without telling the verifier. */
1266 public native void throwException(Throwable ee);
1267
1268 /**
1269 * Atomically updates Java variable to {@code x} if it is currently
1270 * holding {@code expected}.
1271 *
1272 * <p>This operation has memory semantics of a {@code volatile} read
1273 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1274 *
1275 * @return {@code true} if successful
1276 */
1277 @HotSpotIntrinsicCandidate
1278 public final native boolean compareAndSwapObject(Object o, long offset,
1279 Object expected,
1280 Object x);
1281
1282 @HotSpotIntrinsicCandidate
1283 public final native Object compareAndExchangeObjectVolatile(Object o, long offset,
1284 Object expected,
1285 Object x);
1286
1287 @HotSpotIntrinsicCandidate
1288 public final Object compareAndExchangeObjectAcquire(Object o, long offset,
1289 Object expected,
1290 Object x) {
1291 return compareAndExchangeObjectVolatile(o, offset, expected, x);
1292 }
1293
1294 @HotSpotIntrinsicCandidate
1295 public final Object compareAndExchangeObjectRelease(Object o, long offset,
1296 Object expected,
1297 Object x) {
1298 return compareAndExchangeObjectVolatile(o, offset, expected, x);
1299 }
1300
1301 @HotSpotIntrinsicCandidate
1302 public final boolean weakCompareAndSwapObject(Object o, long offset,
1303 Object expected,
1304 Object x) {
1305 return compareAndSwapObject(o, offset, expected, x);
1306 }
1307
1308 @HotSpotIntrinsicCandidate
1309 public final boolean weakCompareAndSwapObjectAcquire(Object o, long offset,
1310 Object expected,
1311 Object x) {
1312 return compareAndSwapObject(o, offset, expected, x);
1313 }
1314
1315 @HotSpotIntrinsicCandidate
1316 public final boolean weakCompareAndSwapObjectRelease(Object o, long offset,
1317 Object expected,
1318 Object x) {
1319 return compareAndSwapObject(o, offset, expected, x);
1320 }
1321
1322 @HotSpotIntrinsicCandidate
1323 public final boolean weakCompareAndSwapObjectVolatile(Object o, long offset,
1324 Object expected,
1325 Object x) {
1326 return compareAndSwapObject(o, offset, expected, x);
1327 }
1328
1329 /**
1330 * Atomically updates Java variable to {@code x} if it is currently
1331 * holding {@code expected}.
1332 *
1333 * <p>This operation has memory semantics of a {@code volatile} read
1334 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1335 *
1336 * @return {@code true} if successful
1337 */
1338 @HotSpotIntrinsicCandidate
1339 public final native boolean compareAndSwapInt(Object o, long offset,
1340 int expected,
1341 int x);
1342
1343 @HotSpotIntrinsicCandidate
1344 public final native int compareAndExchangeIntVolatile(Object o, long offset,
1345 int expected,
1346 int x);
1347
1348 @HotSpotIntrinsicCandidate
1349 public final int compareAndExchangeIntAcquire(Object o, long offset,
1350 int expected,
1351 int x) {
1352 return compareAndExchangeIntVolatile(o, offset, expected, x);
1353 }
1354
1355 @HotSpotIntrinsicCandidate
1356 public final int compareAndExchangeIntRelease(Object o, long offset,
1357 int expected,
1358 int x) {
1359 return compareAndExchangeIntVolatile(o, offset, expected, x);
1360 }
1361
1362 @HotSpotIntrinsicCandidate
1363 public final boolean weakCompareAndSwapInt(Object o, long offset,
1364 int expected,
1365 int x) {
1366 return compareAndSwapInt(o, offset, expected, x);
1367 }
1368
1369 @HotSpotIntrinsicCandidate
1370 public final boolean weakCompareAndSwapIntAcquire(Object o, long offset,
1371 int expected,
1372 int x) {
1373 return compareAndSwapInt(o, offset, expected, x);
1374 }
1375
1376 @HotSpotIntrinsicCandidate
1377 public final boolean weakCompareAndSwapIntRelease(Object o, long offset,
1378 int expected,
1379 int x) {
1380 return compareAndSwapInt(o, offset, expected, x);
1381 }
1382
1383 @HotSpotIntrinsicCandidate
1384 public final boolean weakCompareAndSwapIntVolatile(Object o, long offset,
1385 int expected,
1386 int x) {
1387 return compareAndSwapInt(o, offset, expected, x);
1388 }
1389
1390 @HotSpotIntrinsicCandidate
1391 public final byte compareAndExchangeByteVolatile(Object o, long offset,
1392 byte expected,
1393 byte x) {
1394 long wordOffset = offset & ~3;
1395 int shift = (int) (offset & 3) << 3;
1396 if (BE) {
1397 shift = 24 - shift;
1398 }
1399 int mask = 0xFF << shift;
1400 int maskedExpected = (expected & 0xFF) << shift;
1401 int maskedX = (x & 0xFF) << shift;
1402 int fullWord;
1403 do {
1404 fullWord = getIntVolatile(o, wordOffset);
1405 if ((fullWord & mask) != maskedExpected)
1406 return (byte) ((fullWord & mask) >> shift);
1407 } while (!weakCompareAndSwapIntVolatile(o, wordOffset,
1408 fullWord, (fullWord & ~mask) | maskedX));
1409 return expected;
1410 }
1411
1412 @HotSpotIntrinsicCandidate
1413 public final boolean compareAndSwapByte(Object o, long offset,
1414 byte expected,
1415 byte x) {
1416 return compareAndExchangeByteVolatile(o, offset, expected, x) == expected;
1417 }
1418
1419 @HotSpotIntrinsicCandidate
1420 public final boolean weakCompareAndSwapByteVolatile(Object o, long offset,
1421 byte expected,
1422 byte x) {
1423 return compareAndSwapByte(o, offset, expected, x);
1424 }
1425
1426 @HotSpotIntrinsicCandidate
1427 public final boolean weakCompareAndSwapByteAcquire(Object o, long offset,
1428 byte expected,
1429 byte x) {
1430 return weakCompareAndSwapByteVolatile(o, offset, expected, x);
1431 }
1432
1433 @HotSpotIntrinsicCandidate
1434 public final boolean weakCompareAndSwapByteRelease(Object o, long offset,
1435 byte expected,
1436 byte x) {
1437 return weakCompareAndSwapByteVolatile(o, offset, expected, x);
1438 }
1439
1440 @HotSpotIntrinsicCandidate
1441 public final boolean weakCompareAndSwapByte(Object o, long offset,
1442 byte expected,
1443 byte x) {
1444 return weakCompareAndSwapByteVolatile(o, offset, expected, x);
1445 }
1446
1447 @HotSpotIntrinsicCandidate
1448 public final byte compareAndExchangeByteAcquire(Object o, long offset,
1449 byte expected,
1450 byte x) {
1451 return compareAndExchangeByteVolatile(o, offset, expected, x);
1452 }
1453
1454 @HotSpotIntrinsicCandidate
1455 public final byte compareAndExchangeByteRelease(Object o, long offset,
1456 byte expected,
1457 byte x) {
1458 return compareAndExchangeByteVolatile(o, offset, expected, x);
1459 }
1460
1461 @HotSpotIntrinsicCandidate
1462 public final short compareAndExchangeShortVolatile(Object o, long offset,
1463 short expected,
1464 short x) {
1465 if ((offset & 3) == 3) {
1466 throw new IllegalArgumentException("Update spans the word, not supported");
1467 }
1468 long wordOffset = offset & ~3;
1469 int shift = (int) (offset & 3) << 3;
1470 if (BE) {
1471 shift = 16 - shift;
1472 }
1473 int mask = 0xFFFF << shift;
1474 int maskedExpected = (expected & 0xFFFF) << shift;
1475 int maskedX = (x & 0xFFFF) << shift;
1476 int fullWord;
1477 do {
1478 fullWord = getIntVolatile(o, wordOffset);
1479 if ((fullWord & mask) != maskedExpected) {
1480 return (short) ((fullWord & mask) >> shift);
1481 }
1482 } while (!weakCompareAndSwapIntVolatile(o, wordOffset,
1483 fullWord, (fullWord & ~mask) | maskedX));
1484 return expected;
1485 }
1486
1487 @HotSpotIntrinsicCandidate
1488 public final boolean compareAndSwapShort(Object o, long offset,
1489 short expected,
1490 short x) {
1491 return compareAndExchangeShortVolatile(o, offset, expected, x) == expected;
1492 }
1493
1494 @HotSpotIntrinsicCandidate
1495 public final boolean weakCompareAndSwapShortVolatile(Object o, long offset,
1496 short expected,
1497 short x) {
1498 return compareAndSwapShort(o, offset, expected, x);
1499 }
1500
1501 @HotSpotIntrinsicCandidate
1502 public final boolean weakCompareAndSwapShortAcquire(Object o, long offset,
1503 short expected,
1504 short x) {
1505 return weakCompareAndSwapShortVolatile(o, offset, expected, x);
1506 }
1507
1508 @HotSpotIntrinsicCandidate
1509 public final boolean weakCompareAndSwapShortRelease(Object o, long offset,
1510 short expected,
1511 short x) {
1512 return weakCompareAndSwapShortVolatile(o, offset, expected, x);
1513 }
1514
1515 @HotSpotIntrinsicCandidate
1516 public final boolean weakCompareAndSwapShort(Object o, long offset,
1517 short expected,
1518 short x) {
1519 return weakCompareAndSwapShortVolatile(o, offset, expected, x);
1520 }
1521
1522
1523 @HotSpotIntrinsicCandidate
1524 public final short compareAndExchangeShortAcquire(Object o, long offset,
1525 short expected,
1526 short x) {
1527 return compareAndExchangeShortVolatile(o, offset, expected, x);
1528 }
1529
1530 @HotSpotIntrinsicCandidate
1531 public final short compareAndExchangeShortRelease(Object o, long offset,
1532 short expected,
1533 short x) {
1534 return compareAndExchangeShortVolatile(o, offset, expected, x);
1535 }
1536
1537 @ForceInline
1538 private char s2c(short s) {
1539 return (char) s;
1540 }
1541
1542 @ForceInline
1543 private short c2s(char s) {
1544 return (short) s;
1545 }
1546
1547 @ForceInline
1548 public final boolean compareAndSwapChar(Object o, long offset,
1549 char expected,
1550 char x) {
1551 return compareAndSwapShort(o, offset, c2s(expected), c2s(x));
1552 }
1553
1554 @ForceInline
1555 public final char compareAndExchangeCharVolatile(Object o, long offset,
1556 char expected,
1557 char x) {
1558 return s2c(compareAndExchangeShortVolatile(o, offset, c2s(expected), c2s(x)));
1559 }
1560
1561 @ForceInline
1562 public final char compareAndExchangeCharAcquire(Object o, long offset,
1563 char expected,
1564 char x) {
1565 return s2c(compareAndExchangeShortAcquire(o, offset, c2s(expected), c2s(x)));
1566 }
1567
1568 @ForceInline
1569 public final char compareAndExchangeCharRelease(Object o, long offset,
1570 char expected,
1571 char x) {
1572 return s2c(compareAndExchangeShortRelease(o, offset, c2s(expected), c2s(x)));
1573 }
1574
1575 @ForceInline
1576 public final boolean weakCompareAndSwapCharVolatile(Object o, long offset,
1577 char expected,
1578 char x) {
1579 return weakCompareAndSwapShortVolatile(o, offset, c2s(expected), c2s(x));
1580 }
1581
1582 @ForceInline
1583 public final boolean weakCompareAndSwapCharAcquire(Object o, long offset,
1584 char expected,
1585 char x) {
1586 return weakCompareAndSwapShortAcquire(o, offset, c2s(expected), c2s(x));
1587 }
1588
1589 @ForceInline
1590 public final boolean weakCompareAndSwapCharRelease(Object o, long offset,
1591 char expected,
1592 char x) {
1593 return weakCompareAndSwapShortRelease(o, offset, c2s(expected), c2s(x));
1594 }
1595
1596 @ForceInline
1597 public final boolean weakCompareAndSwapChar(Object o, long offset,
1598 char expected,
1599 char x) {
1600 return weakCompareAndSwapShort(o, offset, c2s(expected), c2s(x));
1601 }
1602
1603 @ForceInline
1604 private boolean byte2bool(byte b) {
1605 return b > 0;
1606 }
1607
1608 @ForceInline
1609 private byte bool2byte(boolean b) {
1610 return b ? (byte)1 : (byte)0;
1611 }
1612
1613 @ForceInline
1614 public final boolean compareAndSwapBoolean(Object o, long offset,
1615 boolean expected,
1616 boolean x) {
1617 return compareAndSwapByte(o, offset, bool2byte(expected), bool2byte(x));
1618 }
1619
1620 @ForceInline
1621 public final boolean compareAndExchangeBooleanVolatile(Object o, long offset,
1622 boolean expected,
1623 boolean x) {
1624 return byte2bool(compareAndExchangeByteVolatile(o, offset, bool2byte(expected), bool2byte(x)));
1625 }
1626
1627 @ForceInline
1628 public final boolean compareAndExchangeBooleanAcquire(Object o, long offset,
1629 boolean expected,
1630 boolean x) {
1631 return byte2bool(compareAndExchangeByteAcquire(o, offset, bool2byte(expected), bool2byte(x)));
1632 }
1633
1634 @ForceInline
1635 public final boolean compareAndExchangeBooleanRelease(Object o, long offset,
1636 boolean expected,
1637 boolean x) {
1638 return byte2bool(compareAndExchangeByteRelease(o, offset, bool2byte(expected), bool2byte(x)));
1639 }
1640
1641 @ForceInline
1642 public final boolean weakCompareAndSwapBooleanVolatile(Object o, long offset,
1643 boolean expected,
1644 boolean x) {
1645 return weakCompareAndSwapByteVolatile(o, offset, bool2byte(expected), bool2byte(x));
1646 }
1647
1648 @ForceInline
1649 public final boolean weakCompareAndSwapBooleanAcquire(Object o, long offset,
1650 boolean expected,
1651 boolean x) {
1652 return weakCompareAndSwapByteAcquire(o, offset, bool2byte(expected), bool2byte(x));
1653 }
1654
1655 @ForceInline
1656 public final boolean weakCompareAndSwapBooleanRelease(Object o, long offset,
1657 boolean expected,
1658 boolean x) {
1659 return weakCompareAndSwapByteRelease(o, offset, bool2byte(expected), bool2byte(x));
1660 }
1661
1662 @ForceInline
1663 public final boolean weakCompareAndSwapBoolean(Object o, long offset,
1664 boolean expected,
1665 boolean x) {
1666 return weakCompareAndSwapByte(o, offset, bool2byte(expected), bool2byte(x));
1667 }
1668
1669 /**
1670 * Atomically updates Java variable to {@code x} if it is currently
1671 * holding {@code expected}.
1672 *
1673 * <p>This operation has memory semantics of a {@code volatile} read
1674 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1675 *
1676 * @return {@code true} if successful
1677 */
1678 @ForceInline
1679 public final boolean compareAndSwapFloat(Object o, long offset,
1680 float expected,
1681 float x) {
1682 return compareAndSwapInt(o, offset,
1683 Float.floatToRawIntBits(expected),
1684 Float.floatToRawIntBits(x));
1685 }
1686
1687 @ForceInline
1688 public final float compareAndExchangeFloatVolatile(Object o, long offset,
1689 float expected,
1690 float x) {
1691 int w = compareAndExchangeIntVolatile(o, offset,
1692 Float.floatToRawIntBits(expected),
1693 Float.floatToRawIntBits(x));
1694 return Float.intBitsToFloat(w);
1695 }
1696
1697 @ForceInline
1698 public final float compareAndExchangeFloatAcquire(Object o, long offset,
1699 float expected,
1700 float x) {
1701 int w = compareAndExchangeIntAcquire(o, offset,
1702 Float.floatToRawIntBits(expected),
1703 Float.floatToRawIntBits(x));
1704 return Float.intBitsToFloat(w);
1705 }
1706
1707 @ForceInline
1708 public final float compareAndExchangeFloatRelease(Object o, long offset,
1709 float expected,
1710 float x) {
1711 int w = compareAndExchangeIntRelease(o, offset,
1712 Float.floatToRawIntBits(expected),
1713 Float.floatToRawIntBits(x));
1714 return Float.intBitsToFloat(w);
1715 }
1716
1717 @ForceInline
1718 public final boolean weakCompareAndSwapFloat(Object o, long offset,
1719 float expected,
1720 float x) {
1721 return weakCompareAndSwapInt(o, offset,
1722 Float.floatToRawIntBits(expected),
1723 Float.floatToRawIntBits(x));
1724 }
1725
1726 @ForceInline
1727 public final boolean weakCompareAndSwapFloatAcquire(Object o, long offset,
1728 float expected,
1729 float x) {
1730 return weakCompareAndSwapIntAcquire(o, offset,
1731 Float.floatToRawIntBits(expected),
1732 Float.floatToRawIntBits(x));
1733 }
1734
1735 @ForceInline
1736 public final boolean weakCompareAndSwapFloatRelease(Object o, long offset,
1737 float expected,
1738 float x) {
1739 return weakCompareAndSwapIntRelease(o, offset,
1740 Float.floatToRawIntBits(expected),
1741 Float.floatToRawIntBits(x));
1742 }
1743
1744 @ForceInline
1745 public final boolean weakCompareAndSwapFloatVolatile(Object o, long offset,
1746 float expected,
1747 float x) {
1748 return weakCompareAndSwapIntVolatile(o, offset,
1749 Float.floatToRawIntBits(expected),
1750 Float.floatToRawIntBits(x));
1751 }
1752
1753 /**
1754 * Atomically updates Java variable to {@code x} if it is currently
1755 * holding {@code expected}.
1756 *
1757 * <p>This operation has memory semantics of a {@code volatile} read
1758 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1759 *
1760 * @return {@code true} if successful
1761 */
1762 @ForceInline
1763 public final boolean compareAndSwapDouble(Object o, long offset,
1764 double expected,
1765 double x) {
1766 return compareAndSwapLong(o, offset,
1767 Double.doubleToRawLongBits(expected),
1768 Double.doubleToRawLongBits(x));
1769 }
1770
1771 @ForceInline
1772 public final double compareAndExchangeDoubleVolatile(Object o, long offset,
1773 double expected,
1774 double x) {
1775 long w = compareAndExchangeLongVolatile(o, offset,
1776 Double.doubleToRawLongBits(expected),
1777 Double.doubleToRawLongBits(x));
1778 return Double.longBitsToDouble(w);
1779 }
1780
1781 @ForceInline
1782 public final double compareAndExchangeDoubleAcquire(Object o, long offset,
1783 double expected,
1784 double x) {
1785 long w = compareAndExchangeLongAcquire(o, offset,
1786 Double.doubleToRawLongBits(expected),
1787 Double.doubleToRawLongBits(x));
1788 return Double.longBitsToDouble(w);
1789 }
1790
1791 @ForceInline
1792 public final double compareAndExchangeDoubleRelease(Object o, long offset,
1793 double expected,
1794 double x) {
1795 long w = compareAndExchangeLongRelease(o, offset,
1796 Double.doubleToRawLongBits(expected),
1797 Double.doubleToRawLongBits(x));
1798 return Double.longBitsToDouble(w);
1799 }
1800
1801 @ForceInline
1802 public final boolean weakCompareAndSwapDouble(Object o, long offset,
1803 double expected,
1804 double x) {
1805 return weakCompareAndSwapLong(o, offset,
1806 Double.doubleToRawLongBits(expected),
1807 Double.doubleToRawLongBits(x));
1808 }
1809
1810 @ForceInline
1811 public final boolean weakCompareAndSwapDoubleAcquire(Object o, long offset,
1812 double expected,
1813 double x) {
1814 return weakCompareAndSwapLongAcquire(o, offset,
1815 Double.doubleToRawLongBits(expected),
1816 Double.doubleToRawLongBits(x));
1817 }
1818
1819 @ForceInline
1820 public final boolean weakCompareAndSwapDoubleRelease(Object o, long offset,
1821 double expected,
1822 double x) {
1823 return weakCompareAndSwapLongRelease(o, offset,
1824 Double.doubleToRawLongBits(expected),
1825 Double.doubleToRawLongBits(x));
1826 }
1827
1828 @ForceInline
1829 public final boolean weakCompareAndSwapDoubleVolatile(Object o, long offset,
1830 double expected,
1831 double x) {
1832 return weakCompareAndSwapLongVolatile(o, offset,
1833 Double.doubleToRawLongBits(expected),
1834 Double.doubleToRawLongBits(x));
1835 }
1836
1837 /**
1838 * Atomically updates Java variable to {@code x} if it is currently
1839 * holding {@code expected}.
1840 *
1841 * <p>This operation has memory semantics of a {@code volatile} read
1842 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1843 *
1844 * @return {@code true} if successful
1845 */
1846 @HotSpotIntrinsicCandidate
1847 public final native boolean compareAndSwapLong(Object o, long offset,
1848 long expected,
1849 long x);
1850
1851 @HotSpotIntrinsicCandidate
1852 public final native long compareAndExchangeLongVolatile(Object o, long offset,
1853 long expected,
1854 long x);
1855
1856 @HotSpotIntrinsicCandidate
1857 public final long compareAndExchangeLongAcquire(Object o, long offset,
1858 long expected,
1859 long x) {
1860 return compareAndExchangeLongVolatile(o, offset, expected, x);
1861 }
1862
1863 @HotSpotIntrinsicCandidate
1864 public final long compareAndExchangeLongRelease(Object o, long offset,
1865 long expected,
1866 long x) {
1867 return compareAndExchangeLongVolatile(o, offset, expected, x);
1868 }
1869
1870 @HotSpotIntrinsicCandidate
1871 public final boolean weakCompareAndSwapLong(Object o, long offset,
1872 long expected,
1873 long x) {
1874 return compareAndSwapLong(o, offset, expected, x);
1875 }
1876
1877 @HotSpotIntrinsicCandidate
1878 public final boolean weakCompareAndSwapLongAcquire(Object o, long offset,
1879 long expected,
1880 long x) {
1881 return compareAndSwapLong(o, offset, expected, x);
1882 }
1883
1884 @HotSpotIntrinsicCandidate
1885 public final boolean weakCompareAndSwapLongRelease(Object o, long offset,
1886 long expected,
1887 long x) {
1888 return compareAndSwapLong(o, offset, expected, x);
1889 }
1890
1891 @HotSpotIntrinsicCandidate
1892 public final boolean weakCompareAndSwapLongVolatile(Object o, long offset,
1893 long expected,
1894 long x) {
1895 return compareAndSwapLong(o, offset, expected, x);
1896 }
1897
1898 /**
1899 * Fetches a reference value from a given Java variable, with volatile
1900 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
1901 */
1902 @HotSpotIntrinsicCandidate
1903 public native Object getObjectVolatile(Object o, long offset);
1904
1905 /**
1906 * Stores a reference value into a given Java variable, with
1907 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
1908 */
1909 @HotSpotIntrinsicCandidate
1910 public native void putObjectVolatile(Object o, long offset, Object x);
1911
1912 /** Volatile version of {@link #getInt(Object, long)} */
1913 @HotSpotIntrinsicCandidate
1914 public native int getIntVolatile(Object o, long offset);
1915
1916 /** Volatile version of {@link #putInt(Object, long, int)} */
1917 @HotSpotIntrinsicCandidate
1918 public native void putIntVolatile(Object o, long offset, int x);
1919
1920 /** Volatile version of {@link #getBoolean(Object, long)} */
1921 @HotSpotIntrinsicCandidate
1922 public native boolean getBooleanVolatile(Object o, long offset);
1923
1924 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
1925 @HotSpotIntrinsicCandidate
1926 public native void putBooleanVolatile(Object o, long offset, boolean x);
1927
1928 /** Volatile version of {@link #getByte(Object, long)} */
1929 @HotSpotIntrinsicCandidate
1930 public native byte getByteVolatile(Object o, long offset);
1931
1932 /** Volatile version of {@link #putByte(Object, long, byte)} */
1933 @HotSpotIntrinsicCandidate
1934 public native void putByteVolatile(Object o, long offset, byte x);
1935
1936 /** Volatile version of {@link #getShort(Object, long)} */
1937 @HotSpotIntrinsicCandidate
1938 public native short getShortVolatile(Object o, long offset);
1939
1940 /** Volatile version of {@link #putShort(Object, long, short)} */
1941 @HotSpotIntrinsicCandidate
1942 public native void putShortVolatile(Object o, long offset, short x);
1943
1944 /** Volatile version of {@link #getChar(Object, long)} */
1945 @HotSpotIntrinsicCandidate
1946 public native char getCharVolatile(Object o, long offset);
1947
1948 /** Volatile version of {@link #putChar(Object, long, char)} */
1949 @HotSpotIntrinsicCandidate
1950 public native void putCharVolatile(Object o, long offset, char x);
1951
1952 /** Volatile version of {@link #getLong(Object, long)} */
1953 @HotSpotIntrinsicCandidate
1954 public native long getLongVolatile(Object o, long offset);
1955
1956 /** Volatile version of {@link #putLong(Object, long, long)} */
1957 @HotSpotIntrinsicCandidate
1958 public native void putLongVolatile(Object o, long offset, long x);
1959
1960 /** Volatile version of {@link #getFloat(Object, long)} */
1961 @HotSpotIntrinsicCandidate
1962 public native float getFloatVolatile(Object o, long offset);
1963
1964 /** Volatile version of {@link #putFloat(Object, long, float)} */
1965 @HotSpotIntrinsicCandidate
1966 public native void putFloatVolatile(Object o, long offset, float x);
1967
1968 /** Volatile version of {@link #getDouble(Object, long)} */
1969 @HotSpotIntrinsicCandidate
1970 public native double getDoubleVolatile(Object o, long offset);
1971
1972 /** Volatile version of {@link #putDouble(Object, long, double)} */
1973 @HotSpotIntrinsicCandidate
1974 public native void putDoubleVolatile(Object o, long offset, double x);
1975
1976
1977
1978 /** Acquire version of {@link #getObjectVolatile(Object, long)} */
1979 @HotSpotIntrinsicCandidate
1980 public final Object getObjectAcquire(Object o, long offset) {
1981 return getObjectVolatile(o, offset);
1982 }
1983
1984 /** Acquire version of {@link #getBooleanVolatile(Object, long)} */
1985 @HotSpotIntrinsicCandidate
1986 public final boolean getBooleanAcquire(Object o, long offset) {
1987 return getBooleanVolatile(o, offset);
1988 }
1989
1990 /** Acquire version of {@link #getByteVolatile(Object, long)} */
1991 @HotSpotIntrinsicCandidate
1992 public final byte getByteAcquire(Object o, long offset) {
1993 return getByteVolatile(o, offset);
1994 }
1995
1996 /** Acquire version of {@link #getShortVolatile(Object, long)} */
1997 @HotSpotIntrinsicCandidate
1998 public final short getShortAcquire(Object o, long offset) {
1999 return getShortVolatile(o, offset);
2000 }
2001
2002 /** Acquire version of {@link #getCharVolatile(Object, long)} */
2003 @HotSpotIntrinsicCandidate
2004 public final char getCharAcquire(Object o, long offset) {
2005 return getCharVolatile(o, offset);
2006 }
2007
2008 /** Acquire version of {@link #getIntVolatile(Object, long)} */
2009 @HotSpotIntrinsicCandidate
2010 public final int getIntAcquire(Object o, long offset) {
2011 return getIntVolatile(o, offset);
2012 }
2013
2014 /** Acquire version of {@link #getFloatVolatile(Object, long)} */
2015 @HotSpotIntrinsicCandidate
2016 public final float getFloatAcquire(Object o, long offset) {
2017 return getFloatVolatile(o, offset);
2018 }
2019
2020 /** Acquire version of {@link #getLongVolatile(Object, long)} */
2021 @HotSpotIntrinsicCandidate
2022 public final long getLongAcquire(Object o, long offset) {
2023 return getLongVolatile(o, offset);
2024 }
2025
2026 /** Acquire version of {@link #getDoubleVolatile(Object, long)} */
2027 @HotSpotIntrinsicCandidate
2028 public final double getDoubleAcquire(Object o, long offset) {
2029 return getDoubleVolatile(o, offset);
2030 }
2031
2032 /*
2033 * Versions of {@link #putObjectVolatile(Object, long, Object)}
2034 * that do not guarantee immediate visibility of the store to
2035 * other threads. This method is generally only useful if the
2036 * underlying field is a Java volatile (or if an array cell, one
2037 * that is otherwise only accessed using volatile accesses).
2038 *
2039 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
2040 */
2041
2042 /** Release version of {@link #putObjectVolatile(Object, long, Object)} */
2043 @HotSpotIntrinsicCandidate
2044 public final void putObjectRelease(Object o, long offset, Object x) {
2045 putObjectVolatile(o, offset, x);
2046 }
2047
2048 /** Release version of {@link #putBooleanVolatile(Object, long, boolean)} */
2049 @HotSpotIntrinsicCandidate
2050 public final void putBooleanRelease(Object o, long offset, boolean x) {
2051 putBooleanVolatile(o, offset, x);
2052 }
2053
2054 /** Release version of {@link #putByteVolatile(Object, long, byte)} */
2055 @HotSpotIntrinsicCandidate
2056 public final void putByteRelease(Object o, long offset, byte x) {
2057 putByteVolatile(o, offset, x);
2058 }
2059
2060 /** Release version of {@link #putShortVolatile(Object, long, short)} */
2061 @HotSpotIntrinsicCandidate
2062 public final void putShortRelease(Object o, long offset, short x) {
2063 putShortVolatile(o, offset, x);
2064 }
2065
2066 /** Release version of {@link #putCharVolatile(Object, long, char)} */
2067 @HotSpotIntrinsicCandidate
2068 public final void putCharRelease(Object o, long offset, char x) {
2069 putCharVolatile(o, offset, x);
2070 }
2071
2072 /** Release version of {@link #putIntVolatile(Object, long, int)} */
2073 @HotSpotIntrinsicCandidate
2074 public final void putIntRelease(Object o, long offset, int x) {
2075 putIntVolatile(o, offset, x);
2076 }
2077
2078 /** Release version of {@link #putFloatVolatile(Object, long, float)} */
2079 @HotSpotIntrinsicCandidate
2080 public final void putFloatRelease(Object o, long offset, float x) {
2081 putFloatVolatile(o, offset, x);
2082 }
2083
2084 /** Release version of {@link #putLongVolatile(Object, long, long)} */
2085 @HotSpotIntrinsicCandidate
2086 public final void putLongRelease(Object o, long offset, long x) {
2087 putLongVolatile(o, offset, x);
2088 }
2089
2090 /** Release version of {@link #putDoubleVolatile(Object, long, double)} */
2091 @HotSpotIntrinsicCandidate
2092 public final void putDoubleRelease(Object o, long offset, double x) {
2093 putDoubleVolatile(o, offset, x);
2094 }
2095
2096 // ------------------------------ Opaque --------------------------------------
2097
2098 /** Opaque version of {@link #getObjectVolatile(Object, long)} */
2099 @HotSpotIntrinsicCandidate
2100 public final Object getObjectOpaque(Object o, long offset) {
2101 return getObjectVolatile(o, offset);
2102 }
2103
2104 /** Opaque version of {@link #getBooleanVolatile(Object, long)} */
2105 @HotSpotIntrinsicCandidate
2106 public final boolean getBooleanOpaque(Object o, long offset) {
2107 return getBooleanVolatile(o, offset);
2108 }
2109
2110 /** Opaque version of {@link #getByteVolatile(Object, long)} */
2111 @HotSpotIntrinsicCandidate
2112 public final byte getByteOpaque(Object o, long offset) {
2113 return getByteVolatile(o, offset);
2114 }
2115
2116 /** Opaque version of {@link #getShortVolatile(Object, long)} */
2117 @HotSpotIntrinsicCandidate
2118 public final short getShortOpaque(Object o, long offset) {
2119 return getShortVolatile(o, offset);
2120 }
2121
2122 /** Opaque version of {@link #getCharVolatile(Object, long)} */
2123 @HotSpotIntrinsicCandidate
2124 public final char getCharOpaque(Object o, long offset) {
2125 return getCharVolatile(o, offset);
2126 }
2127
2128 /** Opaque version of {@link #getIntVolatile(Object, long)} */
2129 @HotSpotIntrinsicCandidate
2130 public final int getIntOpaque(Object o, long offset) {
2131 return getIntVolatile(o, offset);
2132 }
2133
2134 /** Opaque version of {@link #getFloatVolatile(Object, long)} */
2135 @HotSpotIntrinsicCandidate
2136 public final float getFloatOpaque(Object o, long offset) {
2137 return getFloatVolatile(o, offset);
2138 }
2139
2140 /** Opaque version of {@link #getLongVolatile(Object, long)} */
2141 @HotSpotIntrinsicCandidate
2142 public final long getLongOpaque(Object o, long offset) {
2143 return getLongVolatile(o, offset);
2144 }
2145
2146 /** Opaque version of {@link #getDoubleVolatile(Object, long)} */
2147 @HotSpotIntrinsicCandidate
2148 public final double getDoubleOpaque(Object o, long offset) {
2149 return getDoubleVolatile(o, offset);
2150 }
2151
2152 /** Opaque version of {@link #putObjectVolatile(Object, long, Object)} */
2153 @HotSpotIntrinsicCandidate
2154 public final void putObjectOpaque(Object o, long offset, Object x) {
2155 putObjectVolatile(o, offset, x);
2156 }
2157
2158 /** Opaque version of {@link #putBooleanVolatile(Object, long, boolean)} */
2159 @HotSpotIntrinsicCandidate
2160 public final void putBooleanOpaque(Object o, long offset, boolean x) {
2161 putBooleanVolatile(o, offset, x);
2162 }
2163
2164 /** Opaque version of {@link #putByteVolatile(Object, long, byte)} */
2165 @HotSpotIntrinsicCandidate
2166 public final void putByteOpaque(Object o, long offset, byte x) {
2167 putByteVolatile(o, offset, x);
2168 }
2169
2170 /** Opaque version of {@link #putShortVolatile(Object, long, short)} */
2171 @HotSpotIntrinsicCandidate
2172 public final void putShortOpaque(Object o, long offset, short x) {
2173 putShortVolatile(o, offset, x);
2174 }
2175
2176 /** Opaque version of {@link #putCharVolatile(Object, long, char)} */
2177 @HotSpotIntrinsicCandidate
2178 public final void putCharOpaque(Object o, long offset, char x) {
2179 putCharVolatile(o, offset, x);
2180 }
2181
2182 /** Opaque version of {@link #putIntVolatile(Object, long, int)} */
2183 @HotSpotIntrinsicCandidate
2184 public final void putIntOpaque(Object o, long offset, int x) {
2185 putIntVolatile(o, offset, x);
2186 }
2187
2188 /** Opaque version of {@link #putFloatVolatile(Object, long, float)} */
2189 @HotSpotIntrinsicCandidate
2190 public final void putFloatOpaque(Object o, long offset, float x) {
2191 putFloatVolatile(o, offset, x);
2192 }
2193
2194 /** Opaque version of {@link #putLongVolatile(Object, long, long)} */
2195 @HotSpotIntrinsicCandidate
2196 public final void putLongOpaque(Object o, long offset, long x) {
2197 putLongVolatile(o, offset, x);
2198 }
2199
2200 /** Opaque version of {@link #putDoubleVolatile(Object, long, double)} */
2201 @HotSpotIntrinsicCandidate
2202 public final void putDoubleOpaque(Object o, long offset, double x) {
2203 putDoubleVolatile(o, offset, x);
2204 }
2205
2206 /**
2207 * Unblocks the given thread blocked on {@code park}, or, if it is
2208 * not blocked, causes the subsequent call to {@code park} not to
2209 * block. Note: this operation is "unsafe" solely because the
2210 * caller must somehow ensure that the thread has not been
2211 * destroyed. Nothing special is usually required to ensure this
2212 * when called from Java (in which there will ordinarily be a live
2213 * reference to the thread) but this is not nearly-automatically
2214 * so when calling from native code.
2215 *
2216 * @param thread the thread to unpark.
2217 */
2218 @HotSpotIntrinsicCandidate
2219 public native void unpark(Object thread);
2220
2221 /**
2222 * Blocks current thread, returning when a balancing
2223 * {@code unpark} occurs, or a balancing {@code unpark} has
2224 * already occurred, or the thread is interrupted, or, if not
2225 * absolute and time is not zero, the given time nanoseconds have
2226 * elapsed, or if absolute, the given deadline in milliseconds
2227 * since Epoch has passed, or spuriously (i.e., returning for no
2228 * "reason"). Note: This operation is in the Unsafe class only
2229 * because {@code unpark} is, so it would be strange to place it
2230 * elsewhere.
2231 */
2232 @HotSpotIntrinsicCandidate
2233 public native void park(boolean isAbsolute, long time);
2234
2235 /**
2236 * Gets the load average in the system run queue assigned
2237 * to the available processors averaged over various periods of time.
2238 * This method retrieves the given {@code nelem} samples and
2239 * assigns to the elements of the given {@code loadavg} array.
2240 * The system imposes a maximum of 3 samples, representing
2241 * averages over the last 1, 5, and 15 minutes, respectively.
2242 *
2243 * @param loadavg an array of double of size nelems
2244 * @param nelems the number of samples to be retrieved and
2245 * must be 1 to 3.
2246 *
2247 * @return the number of samples actually retrieved; or -1
2248 * if the load average is unobtainable.
2249 */
2250 public int getLoadAverage(double[] loadavg, int nelems) {
2251 if (nelems < 0 || nelems > 3 || nelems > loadavg.length) {
2252 throw new ArrayIndexOutOfBoundsException();
2253 }
2254
2255 return getLoadAverage0(loadavg, nelems);
2256 }
2257
2258 // The following contain CAS-based Java implementations used on
2259 // platforms not supporting native instructions
2260
2261 /**
2262 * Atomically adds the given value to the current value of a field
2263 * or array element within the given object {@code o}
2264 * at the given {@code offset}.
2265 *
2266 * @param o object/array to update the field/element in
2267 * @param offset field/element offset
2268 * @param delta the value to add
2269 * @return the previous value
2270 * @since 1.8
2271 */
2272 @HotSpotIntrinsicCandidate
2273 public final int getAndAddInt(Object o, long offset, int delta) {
2274 int v;
2275 do {
2276 v = getIntVolatile(o, offset);
2277 } while (!weakCompareAndSwapIntVolatile(o, offset, v, v + delta));
2278 return v;
2279 }
2280
2281 /**
2282 * Atomically adds the given value to the current value of a field
2283 * or array element within the given object {@code o}
2284 * at the given {@code offset}.
2285 *
2286 * @param o object/array to update the field/element in
2287 * @param offset field/element offset
2288 * @param delta the value to add
2289 * @return the previous value
2290 * @since 1.8
2291 */
2292 @HotSpotIntrinsicCandidate
2293 public final long getAndAddLong(Object o, long offset, long delta) {
2294 long v;
2295 do {
2296 v = getLongVolatile(o, offset);
2297 } while (!weakCompareAndSwapLongVolatile(o, offset, v, v + delta));
2298 return v;
2299 }
2300
2301 @HotSpotIntrinsicCandidate
2302 public final byte getAndAddByte(Object o, long offset, byte delta) {
2303 byte v;
2304 do {
2305 v = getByteVolatile(o, offset);
2306 } while (!weakCompareAndSwapByteVolatile(o, offset, v, (byte) (v + delta)));
2307 return v;
2308 }
2309
2310 @HotSpotIntrinsicCandidate
2311 public final short getAndAddShort(Object o, long offset, short delta) {
2312 short v;
2313 do {
2314 v = getShortVolatile(o, offset);
2315 } while (!weakCompareAndSwapShortVolatile(o, offset, v, (short) (v + delta)));
2316 return v;
2317 }
2318
2319 @ForceInline
2320 public final char getAndAddChar(Object o, long offset, char delta) {
2321 return (char) getAndAddShort(o, offset, (short) delta);
2322 }
2323
2324 @ForceInline
2325 public final float getAndAddFloat(Object o, long offset, float delta) {
2326 int expectedBits;
2327 float v;
2328 do {
2329 // Load and CAS with the raw bits to avoid issues with NaNs and
2330 // possible bit conversion from signaling NaNs to quiet NaNs that
2331 // may result in the loop not terminating.
2332 expectedBits = getIntVolatile(o, offset);
2333 v = Float.intBitsToFloat(expectedBits);
2334 } while (!weakCompareAndSwapIntVolatile(o, offset,
2335 expectedBits, Float.floatToRawIntBits(v + delta)));
2336 return v;
2337 }
2338
2339 @ForceInline
2340 public final double getAndAddDouble(Object o, long offset, double delta) {
2341 long expectedBits;
2342 double v;
2343 do {
2344 // Load and CAS with the raw bits to avoid issues with NaNs and
2345 // possible bit conversion from signaling NaNs to quiet NaNs that
2346 // may result in the loop not terminating.
2347 expectedBits = getLongVolatile(o, offset);
2348 v = Double.longBitsToDouble(expectedBits);
2349 } while (!weakCompareAndSwapLongVolatile(o, offset,
2350 expectedBits, Double.doubleToRawLongBits(v + delta)));
2351 return v;
2352 }
2353
2354 /**
2355 * Atomically exchanges the given value with the current value of
2356 * a field or array element within the given object {@code o}
2357 * at the given {@code offset}.
2358 *
2359 * @param o object/array to update the field/element in
2360 * @param offset field/element offset
2361 * @param newValue new value
2362 * @return the previous value
2363 * @since 1.8
2364 */
2365 @HotSpotIntrinsicCandidate
2366 public final int getAndSetInt(Object o, long offset, int newValue) {
2367 int v;
2368 do {
2369 v = getIntVolatile(o, offset);
2370 } while (!weakCompareAndSwapIntVolatile(o, offset, v, newValue));
2371 return v;
2372 }
2373
2374 /**
2375 * Atomically exchanges the given value with the current value of
2376 * a field or array element within the given object {@code o}
2377 * at the given {@code offset}.
2378 *
2379 * @param o object/array to update the field/element in
2380 * @param offset field/element offset
2381 * @param newValue new value
2382 * @return the previous value
2383 * @since 1.8
2384 */
2385 @HotSpotIntrinsicCandidate
2386 public final long getAndSetLong(Object o, long offset, long newValue) {
2387 long v;
2388 do {
2389 v = getLongVolatile(o, offset);
2390 } while (!weakCompareAndSwapLongVolatile(o, offset, v, newValue));
2391 return v;
2392 }
2393
2394 /**
2395 * Atomically exchanges the given reference value with the current
2396 * reference value of a field or array element within the given
2397 * object {@code o} at the given {@code offset}.
2398 *
2399 * @param o object/array to update the field/element in
2400 * @param offset field/element offset
2401 * @param newValue new value
2402 * @return the previous value
2403 * @since 1.8
2404 */
2405 @HotSpotIntrinsicCandidate
2406 public final Object getAndSetObject(Object o, long offset, Object newValue) {
2407 Object v;
2408 do {
2409 v = getObjectVolatile(o, offset);
2410 } while (!weakCompareAndSwapObjectVolatile(o, offset, v, newValue));
2411 return v;
2412 }
2413
2414 @HotSpotIntrinsicCandidate
2415 public final byte getAndSetByte(Object o, long offset, byte newValue) {
2416 byte v;
2417 do {
2418 v = getByteVolatile(o, offset);
2419 } while (!weakCompareAndSwapByteVolatile(o, offset, v, newValue));
2420 return v;
2421 }
2422
2423 @ForceInline
2424 public final boolean getAndSetBoolean(Object o, long offset, boolean newValue) {
2425 return byte2bool(getAndSetByte(o, offset, bool2byte(newValue)));
2426 }
2427
2428 @HotSpotIntrinsicCandidate
2429 public final short getAndSetShort(Object o, long offset, short newValue) {
2430 short v;
2431 do {
2432 v = getShortVolatile(o, offset);
2433 } while (!weakCompareAndSwapShortVolatile(o, offset, v, newValue));
2434 return v;
2435 }
2436
2437 @ForceInline
2438 public final char getAndSetChar(Object o, long offset, char newValue) {
2439 return s2c(getAndSetShort(o, offset, c2s(newValue)));
2440 }
2441
2442 @ForceInline
2443 public final float getAndSetFloat(Object o, long offset, float newValue) {
2444 int v = getAndSetInt(o, offset, Float.floatToRawIntBits(newValue));
2445 return Float.intBitsToFloat(v);
2446 }
2447
2448 @ForceInline
2449 public final double getAndSetDouble(Object o, long offset, double newValue) {
2450 long v = getAndSetLong(o, offset, Double.doubleToRawLongBits(newValue));
2451 return Double.longBitsToDouble(v);
2452 }
2453
2454 /**
2455 * Ensures that loads before the fence will not be reordered with loads and
2456 * stores after the fence; a "LoadLoad plus LoadStore barrier".
2457 *
2458 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
2459 * (an "acquire fence").
2460 *
2461 * A pure LoadLoad fence is not provided, since the addition of LoadStore
2462 * is almost always desired, and most current hardware instructions that
2463 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
2464 * @since 1.8
2465 */
2466 @HotSpotIntrinsicCandidate
2467 public native void loadFence();
2468
2469 /**
2470 * Ensures that loads and stores before the fence will not be reordered with
2471 * stores after the fence; a "StoreStore plus LoadStore barrier".
2472 *
2473 * Corresponds to C11 atomic_thread_fence(memory_order_release)
2474 * (a "release fence").
2475 *
2476 * A pure StoreStore fence is not provided, since the addition of LoadStore
2477 * is almost always desired, and most current hardware instructions that
2478 * provide a StoreStore barrier also provide a LoadStore barrier for free.
2479 * @since 1.8
2480 */
2481 @HotSpotIntrinsicCandidate
2482 public native void storeFence();
2483
2484 /**
2485 * Ensures that loads and stores before the fence will not be reordered
2486 * with loads and stores after the fence. Implies the effects of both
2487 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
2488 * barrier.
2489 *
2490 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
2491 * @since 1.8
2492 */
2493 @HotSpotIntrinsicCandidate
2494 public native void fullFence();
2495
2496 /**
2497 * Ensures that loads before the fence will not be reordered with
2498 * loads after the fence.
2499 */
2500 public final void loadLoadFence() {
2501 loadFence();
2502 }
2503
2504 /**
2505 * Ensures that stores before the fence will not be reordered with
2506 * stores after the fence.
2507 */
2508 public final void storeStoreFence() {
2509 storeFence();
2510 }
2511
2512
2513 /**
2514 * Throws IllegalAccessError; for use by the VM for access control
2515 * error support.
2516 * @since 1.8
2517 */
2518 private static void throwIllegalAccessError() {
2519 throw new IllegalAccessError();
2520 }
2521
2522 /**
2523 * @return Returns true if the native byte ordering of this
2524 * platform is big-endian, false if it is little-endian.
2525 */
2526 public final boolean isBigEndian() { return BE; }
2527
2528 /**
2529 * @return Returns true if this platform is capable of performing
2530 * accesses at addresses which are not aligned for the type of the
2531 * primitive type being accessed, false otherwise.
2532 */
2533 public final boolean unalignedAccess() { return unalignedAccess; }
2534
2535 /**
2536 * Fetches a value at some byte offset into a given Java object.
2537 * More specifically, fetches a value within the given object
2538 * <code>o</code> at the given offset, or (if <code>o</code> is
2539 * null) from the memory address whose numerical value is the
2540 * given offset. <p>
2541 *
2542 * The specification of this method is the same as {@link
2543 * #getLong(Object, long)} except that the offset does not need to
2544 * have been obtained from {@link #objectFieldOffset} on the
2545 * {@link java.lang.reflect.Field} of some Java field. The value
2546 * in memory is raw data, and need not correspond to any Java
2547 * variable. Unless <code>o</code> is null, the value accessed
2548 * must be entirely within the allocated object. The endianness
2549 * of the value in memory is the endianness of the native platform.
2550 *
2551 * <p> The read will be atomic with respect to the largest power
2552 * of two that divides the GCD of the offset and the storage size.
2553 * For example, getLongUnaligned will make atomic reads of 2-, 4-,
2554 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
2555 * respectively. There are no other guarantees of atomicity.
2556 * <p>
2557 * 8-byte atomicity is only guaranteed on platforms on which
2558 * support atomic accesses to longs.
2559 *
2560 * @param o Java heap object in which the value resides, if any, else
2561 * null
2562 * @param offset The offset in bytes from the start of the object
2563 * @return the value fetched from the indicated object
2564 * @throws RuntimeException No defined exceptions are thrown, not even
2565 * {@link NullPointerException}
2566 * @since 9
2567 */
2568 @HotSpotIntrinsicCandidate
2569 public final long getLongUnaligned(Object o, long offset) {
2570 if ((offset & 7) == 0) {
2571 return getLong(o, offset);
2572 } else if ((offset & 3) == 0) {
2573 return makeLong(getInt(o, offset),
2574 getInt(o, offset + 4));
2575 } else if ((offset & 1) == 0) {
2576 return makeLong(getShort(o, offset),
2577 getShort(o, offset + 2),
2578 getShort(o, offset + 4),
2579 getShort(o, offset + 6));
2580 } else {
2581 return makeLong(getByte(o, offset),
2582 getByte(o, offset + 1),
2583 getByte(o, offset + 2),
2584 getByte(o, offset + 3),
2585 getByte(o, offset + 4),
2586 getByte(o, offset + 5),
2587 getByte(o, offset + 6),
2588 getByte(o, offset + 7));
2589 }
2590 }
2591 /**
2592 * As {@link #getLongUnaligned(Object, long)} but with an
2593 * additional argument which specifies the endianness of the value
2594 * as stored in memory.
2595 *
2596 * @param o Java heap object in which the variable resides
2597 * @param offset The offset in bytes from the start of the object
2598 * @param bigEndian The endianness of the value
2599 * @return the value fetched from the indicated object
2600 * @since 9
2601 */
2602 public final long getLongUnaligned(Object o, long offset, boolean bigEndian) {
2603 return convEndian(bigEndian, getLongUnaligned(o, offset));
2604 }
2605
2606 /** @see #getLongUnaligned(Object, long) */
2607 @HotSpotIntrinsicCandidate
2608 public final int getIntUnaligned(Object o, long offset) {
2609 if ((offset & 3) == 0) {
2610 return getInt(o, offset);
2611 } else if ((offset & 1) == 0) {
2612 return makeInt(getShort(o, offset),
2613 getShort(o, offset + 2));
2614 } else {
2615 return makeInt(getByte(o, offset),
2616 getByte(o, offset + 1),
2617 getByte(o, offset + 2),
2618 getByte(o, offset + 3));
2619 }
2620 }
2621 /** @see #getLongUnaligned(Object, long, boolean) */
2622 public final int getIntUnaligned(Object o, long offset, boolean bigEndian) {
2623 return convEndian(bigEndian, getIntUnaligned(o, offset));
2624 }
2625
2626 /** @see #getLongUnaligned(Object, long) */
2627 @HotSpotIntrinsicCandidate
2628 public final short getShortUnaligned(Object o, long offset) {
2629 if ((offset & 1) == 0) {
2630 return getShort(o, offset);
2631 } else {
2632 return makeShort(getByte(o, offset),
2633 getByte(o, offset + 1));
2634 }
2635 }
2636 /** @see #getLongUnaligned(Object, long, boolean) */
2637 public final short getShortUnaligned(Object o, long offset, boolean bigEndian) {
2638 return convEndian(bigEndian, getShortUnaligned(o, offset));
2639 }
2640
2641 /** @see #getLongUnaligned(Object, long) */
2642 @HotSpotIntrinsicCandidate
2643 public final char getCharUnaligned(Object o, long offset) {
2644 if ((offset & 1) == 0) {
2645 return getChar(o, offset);
2646 } else {
2647 return (char)makeShort(getByte(o, offset),
2648 getByte(o, offset + 1));
2649 }
2650 }
2651
2652 /** @see #getLongUnaligned(Object, long, boolean) */
2653 public final char getCharUnaligned(Object o, long offset, boolean bigEndian) {
2654 return convEndian(bigEndian, getCharUnaligned(o, offset));
2655 }
2656
2657 /**
2658 * Stores a value at some byte offset into a given Java object.
2659 * <p>
2660 * The specification of this method is the same as {@link
2661 * #getLong(Object, long)} except that the offset does not need to
2662 * have been obtained from {@link #objectFieldOffset} on the
2663 * {@link java.lang.reflect.Field} of some Java field. The value
2664 * in memory is raw data, and need not correspond to any Java
2665 * variable. The endianness of the value in memory is the
2666 * endianness of the native platform.
2667 * <p>
2668 * The write will be atomic with respect to the largest power of
2669 * two that divides the GCD of the offset and the storage size.
2670 * For example, putLongUnaligned will make atomic writes of 2-, 4-,
2671 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
2672 * respectively. There are no other guarantees of atomicity.
2673 * <p>
2674 * 8-byte atomicity is only guaranteed on platforms on which
2675 * support atomic accesses to longs.
2676 *
2677 * @param o Java heap object in which the value resides, if any, else
2678 * null
2679 * @param offset The offset in bytes from the start of the object
2680 * @param x the value to store
2681 * @throws RuntimeException No defined exceptions are thrown, not even
2682 * {@link NullPointerException}
2683 * @since 9
2684 */
2685 @HotSpotIntrinsicCandidate
2686 public final void putLongUnaligned(Object o, long offset, long x) {
2687 if ((offset & 7) == 0) {
2688 putLong(o, offset, x);
2689 } else if ((offset & 3) == 0) {
2690 putLongParts(o, offset,
2691 (int)(x >> 0),
2692 (int)(x >>> 32));
2693 } else if ((offset & 1) == 0) {
2694 putLongParts(o, offset,
2695 (short)(x >>> 0),
2696 (short)(x >>> 16),
2697 (short)(x >>> 32),
2698 (short)(x >>> 48));
2699 } else {
2700 putLongParts(o, offset,
2701 (byte)(x >>> 0),
2702 (byte)(x >>> 8),
2703 (byte)(x >>> 16),
2704 (byte)(x >>> 24),
2705 (byte)(x >>> 32),
2706 (byte)(x >>> 40),
2707 (byte)(x >>> 48),
2708 (byte)(x >>> 56));
2709 }
2710 }
2711
2712 /**
2713 * As {@link #putLongUnaligned(Object, long, long)} but with an additional
2714 * argument which specifies the endianness of the value as stored in memory.
2715 * @param o Java heap object in which the value resides
2716 * @param offset The offset in bytes from the start of the object
2717 * @param x the value to store
2718 * @param bigEndian The endianness of the value
2719 * @throws RuntimeException No defined exceptions are thrown, not even
2720 * {@link NullPointerException}
2721 * @since 9
2722 */
2723 public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) {
2724 putLongUnaligned(o, offset, convEndian(bigEndian, x));
2725 }
2726
2727 /** @see #putLongUnaligned(Object, long, long) */
2728 @HotSpotIntrinsicCandidate
2729 public final void putIntUnaligned(Object o, long offset, int x) {
2730 if ((offset & 3) == 0) {
2731 putInt(o, offset, x);
2732 } else if ((offset & 1) == 0) {
2733 putIntParts(o, offset,
2734 (short)(x >> 0),
2735 (short)(x >>> 16));
2736 } else {
2737 putIntParts(o, offset,
2738 (byte)(x >>> 0),
2739 (byte)(x >>> 8),
2740 (byte)(x >>> 16),
2741 (byte)(x >>> 24));
2742 }
2743 }
2744 /** @see #putLongUnaligned(Object, long, long, boolean) */
2745 public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) {
2746 putIntUnaligned(o, offset, convEndian(bigEndian, x));
2747 }
2748
2749 /** @see #putLongUnaligned(Object, long, long) */
2750 @HotSpotIntrinsicCandidate
2751 public final void putShortUnaligned(Object o, long offset, short x) {
2752 if ((offset & 1) == 0) {
2753 putShort(o, offset, x);
2754 } else {
2755 putShortParts(o, offset,
2756 (byte)(x >>> 0),
2757 (byte)(x >>> 8));
2758 }
2759 }
2760 /** @see #putLongUnaligned(Object, long, long, boolean) */
2761 public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) {
2762 putShortUnaligned(o, offset, convEndian(bigEndian, x));
2763 }
2764
2765 /** @see #putLongUnaligned(Object, long, long) */
2766 @HotSpotIntrinsicCandidate
2767 public final void putCharUnaligned(Object o, long offset, char x) {
2768 putShortUnaligned(o, offset, (short)x);
2769 }
2770 /** @see #putLongUnaligned(Object, long, long, boolean) */
2771 public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) {
2772 putCharUnaligned(o, offset, convEndian(bigEndian, x));
2773 }
2774
2775 // JVM interface methods
2776 // BE is true iff the native endianness of this platform is big.
2777 private static final boolean BE = theUnsafe.isBigEndian0();
2778
2779 // unalignedAccess is true iff this platform can perform unaligned accesses.
2780 private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
2781
2782 private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
2783
2784 // These methods construct integers from bytes. The byte ordering
2785 // is the native endianness of this platform.
2786 private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
2787 return ((toUnsignedLong(i0) << pickPos(56, 0))
2788 | (toUnsignedLong(i1) << pickPos(56, 8))
2789 | (toUnsignedLong(i2) << pickPos(56, 16))
2790 | (toUnsignedLong(i3) << pickPos(56, 24))
2791 | (toUnsignedLong(i4) << pickPos(56, 32))
2792 | (toUnsignedLong(i5) << pickPos(56, 40))
2793 | (toUnsignedLong(i6) << pickPos(56, 48))
2794 | (toUnsignedLong(i7) << pickPos(56, 56)));
2795 }
2796 private static long makeLong(short i0, short i1, short i2, short i3) {
2797 return ((toUnsignedLong(i0) << pickPos(48, 0))
2798 | (toUnsignedLong(i1) << pickPos(48, 16))
2799 | (toUnsignedLong(i2) << pickPos(48, 32))
2800 | (toUnsignedLong(i3) << pickPos(48, 48)));
2801 }
2802 private static long makeLong(int i0, int i1) {
2803 return (toUnsignedLong(i0) << pickPos(32, 0))
2804 | (toUnsignedLong(i1) << pickPos(32, 32));
2805 }
2806 private static int makeInt(short i0, short i1) {
2807 return (toUnsignedInt(i0) << pickPos(16, 0))
2808 | (toUnsignedInt(i1) << pickPos(16, 16));
2809 }
2810 private static int makeInt(byte i0, byte i1, byte i2, byte i3) {
2811 return ((toUnsignedInt(i0) << pickPos(24, 0))
2812 | (toUnsignedInt(i1) << pickPos(24, 8))
2813 | (toUnsignedInt(i2) << pickPos(24, 16))
2814 | (toUnsignedInt(i3) << pickPos(24, 24)));
2815 }
2816 private static short makeShort(byte i0, byte i1) {
2817 return (short)((toUnsignedInt(i0) << pickPos(8, 0))
2818 | (toUnsignedInt(i1) << pickPos(8, 8)));
2819 }
2820
2821 private static byte pick(byte le, byte be) { return BE ? be : le; }
2822 private static short pick(short le, short be) { return BE ? be : le; }
2823 private static int pick(int le, int be) { return BE ? be : le; }
2824
2825 // These methods write integers to memory from smaller parts
2826 // provided by their caller. The ordering in which these parts
2827 // are written is the native endianness of this platform.
2828 private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
2829 putByte(o, offset + 0, pick(i0, i7));
2830 putByte(o, offset + 1, pick(i1, i6));
2831 putByte(o, offset + 2, pick(i2, i5));
2832 putByte(o, offset + 3, pick(i3, i4));
2833 putByte(o, offset + 4, pick(i4, i3));
2834 putByte(o, offset + 5, pick(i5, i2));
2835 putByte(o, offset + 6, pick(i6, i1));
2836 putByte(o, offset + 7, pick(i7, i0));
2837 }
2838 private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) {
2839 putShort(o, offset + 0, pick(i0, i3));
2840 putShort(o, offset + 2, pick(i1, i2));
2841 putShort(o, offset + 4, pick(i2, i1));
2842 putShort(o, offset + 6, pick(i3, i0));
2843 }
2844 private void putLongParts(Object o, long offset, int i0, int i1) {
2845 putInt(o, offset + 0, pick(i0, i1));
2846 putInt(o, offset + 4, pick(i1, i0));
2847 }
2848 private void putIntParts(Object o, long offset, short i0, short i1) {
2849 putShort(o, offset + 0, pick(i0, i1));
2850 putShort(o, offset + 2, pick(i1, i0));
2851 }
2852 private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) {
2853 putByte(o, offset + 0, pick(i0, i3));
2854 putByte(o, offset + 1, pick(i1, i2));
2855 putByte(o, offset + 2, pick(i2, i1));
2856 putByte(o, offset + 3, pick(i3, i0));
2857 }
2858 private void putShortParts(Object o, long offset, byte i0, byte i1) {
2859 putByte(o, offset + 0, pick(i0, i1));
2860 putByte(o, offset + 1, pick(i1, i0));
2861 }
2862
2863 // Zero-extend an integer
2864 private static int toUnsignedInt(byte n) { return n & 0xff; }
2865 private static int toUnsignedInt(short n) { return n & 0xffff; }
2866 private static long toUnsignedLong(byte n) { return n & 0xffl; }
2867 private static long toUnsignedLong(short n) { return n & 0xffffl; }
2868 private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
2869
2870 // Maybe byte-reverse an integer
2871 private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
2872 private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
2873 private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
2874 private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
2875
2876
2877
2878 private native long allocateMemory0(long bytes);
2879 private native long reallocateMemory0(long address, long bytes);
2880 private native void freeMemory0(long address);
2881 private native void setMemory0(Object o, long offset, long bytes, byte value);
2882 @HotSpotIntrinsicCandidate
2883 private native void copyMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes);
2884 private native void copySwapMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes, long elemSize);
2885 private native long objectFieldOffset0(Field f);
2886 private native long staticFieldOffset0(Field f);
2887 private native Object staticFieldBase0(Field f);
2888 private native boolean shouldBeInitialized0(Class<?> c);
2889 private native void ensureClassInitialized0(Class<?> c);
2890 private native int arrayBaseOffset0(Class<?> arrayClass);
2891 private native int arrayIndexScale0(Class<?> arrayClass);
2892 private native int addressSize0();
2893 private native Class<?> defineAnonymousClass0(Class<?> hostClass, byte[] data, Object[] cpPatches);
2894 private native int getLoadAverage0(double[] loadavg, int nelems);
2895 private native boolean unalignedAccess0();
2896 private native boolean isBigEndian0();
2897 }