1 /*
2 * Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.misc;
27
28 import java.lang.reflect.Field;
29 import java.security.ProtectionDomain;
30
31 import sun.reflect.CallerSensitive;
32 import sun.reflect.Reflection;
33 import jdk.internal.misc.VM;
34
35 import jdk.internal.HotSpotIntrinsicCandidate;
36
37
38 /**
39 * A collection of methods for performing low-level, unsafe operations.
40 * Although the class and all methods are public, use of this class is
41 * limited because only trusted code can obtain instances of it.
42 *
43 * @author John R. Rose
44 * @see #getUnsafe
45 */
46
47 public final class Unsafe {
48
49 private static native void registerNatives();
50 static {
51 registerNatives();
52 sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe");
53 }
54
55 private Unsafe() {}
56
57 private static final Unsafe theUnsafe = new Unsafe();
58
59 /**
60 * Provides the caller with the capability of performing unsafe
61 * operations.
62 *
63 * <p>The returned {@code Unsafe} object should be carefully guarded
64 * by the caller, since it can be used to read and write data at arbitrary
65 * memory addresses. It must never be passed to untrusted code.
66 *
67 * <p>Most methods in this class are very low-level, and correspond to a
68 * small number of hardware instructions (on typical machines). Compilers
69 * are encouraged to optimize these methods accordingly.
70 *
71 * <p>Here is a suggested idiom for using unsafe operations:
72 *
73 * <pre> {@code
74 * class MyTrustedClass {
75 * private static final Unsafe unsafe = Unsafe.getUnsafe();
76 * ...
77 * private long myCountAddress = ...;
78 * public int getCount() { return unsafe.getByte(myCountAddress); }
79 * }}</pre>
80 *
81 * (It may assist compilers to make the local variable {@code final}.)
82 *
83 * @throws SecurityException if a security manager exists and its
84 * {@code checkPropertiesAccess} method doesn't allow
85 * access to the system properties.
86 */
87 @CallerSensitive
88 public static Unsafe getUnsafe() {
89 Class<?> caller = Reflection.getCallerClass();
90 if (!VM.isSystemDomainLoader(caller.getClassLoader()))
91 throw new SecurityException("Unsafe");
92 return theUnsafe;
93 }
94
95 /// peek and poke operations
96 /// (compilers should optimize these to memory ops)
97
98 // These work on object fields in the Java heap.
99 // They will not work on elements of packed arrays.
100
101 /**
102 * Fetches a value from a given Java variable.
103 * More specifically, fetches a field or array element within the given
104 * object {@code o} at the given offset, or (if {@code o} is null)
105 * from the memory address whose numerical value is the given offset.
106 * <p>
107 * The results are undefined unless one of the following cases is true:
108 * <ul>
109 * <li>The offset was obtained from {@link #objectFieldOffset} on
110 * the {@link java.lang.reflect.Field} of some Java field and the object
111 * referred to by {@code o} is of a class compatible with that
112 * field's class.
113 *
114 * <li>The offset and object reference {@code o} (either null or
115 * non-null) were both obtained via {@link #staticFieldOffset}
116 * and {@link #staticFieldBase} (respectively) from the
117 * reflective {@link Field} representation of some Java field.
118 *
119 * <li>The object referred to by {@code o} is an array, and the offset
120 * is an integer of the form {@code B+N*S}, where {@code N} is
121 * a valid index into the array, and {@code B} and {@code S} are
122 * the values obtained by {@link #arrayBaseOffset} and {@link
123 * #arrayIndexScale} (respectively) from the array's class. The value
124 * referred to is the {@code N}<em>th</em> element of the array.
125 *
126 * </ul>
127 * <p>
128 * If one of the above cases is true, the call references a specific Java
129 * variable (field or array element). However, the results are undefined
130 * if that variable is not in fact of the type returned by this method.
131 * <p>
132 * This method refers to a variable by means of two parameters, and so
133 * it provides (in effect) a <em>double-register</em> addressing mode
134 * for Java variables. When the object reference is null, this method
135 * uses its offset as an absolute address. This is similar in operation
136 * to methods such as {@link #getInt(long)}, which provide (in effect) a
137 * <em>single-register</em> addressing mode for non-Java variables.
138 * However, because Java variables may have a different layout in memory
139 * from non-Java variables, programmers should not assume that these
140 * two addressing modes are ever equivalent. Also, programmers should
141 * remember that offsets from the double-register addressing mode cannot
142 * be portably confused with longs used in the single-register addressing
143 * mode.
144 *
145 * @param o Java heap object in which the variable resides, if any, else
146 * null
147 * @param offset indication of where the variable resides in a Java heap
148 * object, if any, else a memory address locating the variable
149 * statically
150 * @return the value fetched from the indicated Java variable
151 * @throws RuntimeException No defined exceptions are thrown, not even
152 * {@link NullPointerException}
153 */
154 @HotSpotIntrinsicCandidate
155 public native int getInt(Object o, long offset);
156
157 /**
158 * Stores a value into a given Java variable.
159 * <p>
160 * The first two parameters are interpreted exactly as with
161 * {@link #getInt(Object, long)} to refer to a specific
162 * Java variable (field or array element). The given value
163 * is stored into that variable.
164 * <p>
165 * The variable must be of the same type as the method
166 * parameter {@code x}.
167 *
168 * @param o Java heap object in which the variable resides, if any, else
169 * null
170 * @param offset indication of where the variable resides in a Java heap
171 * object, if any, else a memory address locating the variable
172 * statically
173 * @param x the value to store into the indicated Java variable
174 * @throws RuntimeException No defined exceptions are thrown, not even
175 * {@link NullPointerException}
176 */
177 @HotSpotIntrinsicCandidate
178 public native void putInt(Object o, long offset, int x);
179
180 /**
181 * Fetches a reference value from a given Java variable.
182 * @see #getInt(Object, long)
183 */
184 @HotSpotIntrinsicCandidate
185 public native Object getObject(Object o, long offset);
186
187 /**
188 * Stores a reference value into a given Java variable.
189 * <p>
190 * Unless the reference {@code x} being stored is either null
191 * or matches the field type, the results are undefined.
192 * If the reference {@code o} is non-null, card marks or
193 * other store barriers for that object (if the VM requires them)
194 * are updated.
195 * @see #putInt(Object, long, int)
196 */
197 @HotSpotIntrinsicCandidate
198 public native void putObject(Object o, long offset, Object x);
199
200 /** @see #getInt(Object, long) */
201 @HotSpotIntrinsicCandidate
202 public native boolean getBoolean(Object o, long offset);
203 /** @see #putInt(Object, long, int) */
204 @HotSpotIntrinsicCandidate
205 public native void putBoolean(Object o, long offset, boolean x);
206 /** @see #getInt(Object, long) */
207 @HotSpotIntrinsicCandidate
208 public native byte getByte(Object o, long offset);
209 /** @see #putInt(Object, long, int) */
210 @HotSpotIntrinsicCandidate
211 public native void putByte(Object o, long offset, byte x);
212 /** @see #getInt(Object, long) */
213 @HotSpotIntrinsicCandidate
214 public native short getShort(Object o, long offset);
215 /** @see #putInt(Object, long, int) */
216 @HotSpotIntrinsicCandidate
217 public native void putShort(Object o, long offset, short x);
218 /** @see #getInt(Object, long) */
219 @HotSpotIntrinsicCandidate
220 public native char getChar(Object o, long offset);
221 /** @see #putInt(Object, long, int) */
222 @HotSpotIntrinsicCandidate
223 public native void putChar(Object o, long offset, char x);
224 /** @see #getInt(Object, long) */
225 @HotSpotIntrinsicCandidate
226 public native long getLong(Object o, long offset);
227 /** @see #putInt(Object, long, int) */
228 @HotSpotIntrinsicCandidate
229 public native void putLong(Object o, long offset, long x);
230 /** @see #getInt(Object, long) */
231 @HotSpotIntrinsicCandidate
232 public native float getFloat(Object o, long offset);
233 /** @see #putInt(Object, long, int) */
234 @HotSpotIntrinsicCandidate
235 public native void putFloat(Object o, long offset, float x);
236 /** @see #getInt(Object, long) */
237 @HotSpotIntrinsicCandidate
238 public native double getDouble(Object o, long offset);
239 /** @see #putInt(Object, long, int) */
240 @HotSpotIntrinsicCandidate
241 public native void putDouble(Object o, long offset, double x);
242
243 // These read VM internal data.
244
245 /**
246 * Fetches an uncompressed reference value from a given native variable
247 * ignoring the VM's compressed references mode.
248 *
249 * @param address a memory address locating the variable
250 * @return the value fetched from the indicated native variable
251 */
252 public native Object getUncompressedObject(long address);
253
254 /**
255 * Fetches the {@link java.lang.Class} Java mirror for the given native
256 * metaspace {@code Klass} pointer.
257 *
258 * @param metaspaceKlass a native metaspace {@code Klass} pointer
259 * @return the {@link java.lang.Class} Java mirror
260 */
261 public native Class<?> getJavaMirror(long metaspaceKlass);
262
263 /**
264 * Fetches a native metaspace {@code Klass} pointer for the given Java
265 * object.
266 *
267 * @param o Java heap object for which to fetch the class pointer
268 * @return a native metaspace {@code Klass} pointer
269 */
270 public native long getKlassPointer(Object o);
271
272 // These work on values in the C heap.
273
274 /**
275 * Fetches a value from a given memory address. If the address is zero, or
276 * does not point into a block obtained from {@link #allocateMemory}, the
277 * results are undefined.
278 *
279 * @see #allocateMemory
280 */
281 @HotSpotIntrinsicCandidate
282 public native byte getByte(long address);
283
284 /**
285 * Stores a value into a given memory address. If the address is zero, or
286 * does not point into a block obtained from {@link #allocateMemory}, the
287 * results are undefined.
288 *
289 * @see #getByte(long)
290 */
291 @HotSpotIntrinsicCandidate
292 public native void putByte(long address, byte x);
293
294 /** @see #getByte(long) */
295 @HotSpotIntrinsicCandidate
296 public native short getShort(long address);
297 /** @see #putByte(long, byte) */
298 @HotSpotIntrinsicCandidate
299 public native void putShort(long address, short x);
300 /** @see #getByte(long) */
301 @HotSpotIntrinsicCandidate
302 public native char getChar(long address);
303 /** @see #putByte(long, byte) */
304 @HotSpotIntrinsicCandidate
305 public native void putChar(long address, char x);
306 /** @see #getByte(long) */
307 @HotSpotIntrinsicCandidate
308 public native int getInt(long address);
309 /** @see #putByte(long, byte) */
310 @HotSpotIntrinsicCandidate
311 public native void putInt(long address, int x);
312 /** @see #getByte(long) */
313 @HotSpotIntrinsicCandidate
314 public native long getLong(long address);
315 /** @see #putByte(long, byte) */
316 @HotSpotIntrinsicCandidate
317 public native void putLong(long address, long x);
318 /** @see #getByte(long) */
319 @HotSpotIntrinsicCandidate
320 public native float getFloat(long address);
321 /** @see #putByte(long, byte) */
322 @HotSpotIntrinsicCandidate
323 public native void putFloat(long address, float x);
324 /** @see #getByte(long) */
325 @HotSpotIntrinsicCandidate
326 public native double getDouble(long address);
327 /** @see #putByte(long, byte) */
328 @HotSpotIntrinsicCandidate
329 public native void putDouble(long address, double x);
330
331 /**
332 * Fetches a native pointer from a given memory address. If the address is
333 * zero, or does not point into a block obtained from {@link
334 * #allocateMemory}, the results are undefined.
335 *
336 * <p>If the native pointer is less than 64 bits wide, it is extended as
337 * an unsigned number to a Java long. The pointer may be indexed by any
338 * given byte offset, simply by adding that offset (as a simple integer) to
339 * the long representing the pointer. The number of bytes actually read
340 * from the target address may be determined by consulting {@link
341 * #addressSize}.
342 *
343 * @see #allocateMemory
344 */
345 @HotSpotIntrinsicCandidate
346 public native long getAddress(long address);
347
348 /**
349 * Stores a native pointer into a given memory address. If the address is
350 * zero, or does not point into a block obtained from {@link
351 * #allocateMemory}, the results are undefined.
352 *
353 * <p>The number of bytes actually written at the target address may be
354 * determined by consulting {@link #addressSize}.
355 *
356 * @see #getAddress(long)
357 */
358 @HotSpotIntrinsicCandidate
359 public native void putAddress(long address, long x);
360
361 /// wrappers for malloc, realloc, free:
362
363 /**
364 * Allocates a new block of native memory, of the given size in bytes. The
365 * contents of the memory are uninitialized; they will generally be
366 * garbage. The resulting native pointer will never be zero, and will be
367 * aligned for all value types. Dispose of this memory by calling {@link
368 * #freeMemory}, or resize it with {@link #reallocateMemory}.
369 *
370 * @throws IllegalArgumentException if the size is negative or too large
371 * for the native size_t type
372 *
373 * @throws OutOfMemoryError if the allocation is refused by the system
374 *
375 * @see #getByte(long)
376 * @see #putByte(long, byte)
377 */
378 public native long allocateMemory(long bytes);
379
380 /**
381 * Resizes a new block of native memory, to the given size in bytes. The
382 * contents of the new block past the size of the old block are
383 * uninitialized; they will generally be garbage. The resulting native
384 * pointer will be zero if and only if the requested size is zero. The
385 * resulting native pointer will be aligned for all value types. Dispose
386 * of this memory by calling {@link #freeMemory}, or resize it with {@link
387 * #reallocateMemory}. The address passed to this method may be null, in
388 * which case an allocation will be performed.
389 *
390 * @throws IllegalArgumentException if the size is negative or too large
391 * for the native size_t type
392 *
393 * @throws OutOfMemoryError if the allocation is refused by the system
394 *
395 * @see #allocateMemory
396 */
397 public native long reallocateMemory(long address, long bytes);
398
399 /**
400 * Sets all bytes in a given block of memory to a fixed value
401 * (usually zero).
402 *
403 * <p>This method determines a block's base address by means of two parameters,
404 * and so it provides (in effect) a <em>double-register</em> addressing mode,
405 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
406 * the offset supplies an absolute base address.
407 *
408 * <p>The stores are in coherent (atomic) units of a size determined
409 * by the address and length parameters. If the effective address and
410 * length are all even modulo 8, the stores take place in 'long' units.
411 * If the effective address and length are (resp.) even modulo 4 or 2,
412 * the stores take place in units of 'int' or 'short'.
413 *
414 * @since 1.7
415 */
416 public native void setMemory(Object o, long offset, long bytes, byte value);
417
418 /**
419 * Sets all bytes in a given block of memory to a fixed value
420 * (usually zero). This provides a <em>single-register</em> addressing mode,
421 * as discussed in {@link #getInt(Object,long)}.
422 *
423 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
424 */
425 public void setMemory(long address, long bytes, byte value) {
426 setMemory(null, address, bytes, value);
427 }
428
429 /**
430 * Sets all bytes in a given block of memory to a copy of another
431 * block.
432 *
433 * <p>This method determines each block's base address by means of two parameters,
434 * and so it provides (in effect) a <em>double-register</em> addressing mode,
435 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
436 * the offset supplies an absolute base address.
437 *
438 * <p>The transfers are in coherent (atomic) units of a size determined
439 * by the address and length parameters. If the effective addresses and
440 * length are all even modulo 8, the transfer takes place in 'long' units.
441 * If the effective addresses and length are (resp.) even modulo 4 or 2,
442 * the transfer takes place in units of 'int' or 'short'.
443 *
444 * @since 1.7
445 */
446 @HotSpotIntrinsicCandidate
447 public native void copyMemory(Object srcBase, long srcOffset,
448 Object destBase, long destOffset,
449 long bytes);
450 /**
451 * Sets all bytes in a given block of memory to a copy of another
452 * block. This provides a <em>single-register</em> addressing mode,
453 * as discussed in {@link #getInt(Object,long)}.
454 *
455 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
456 */
457 public void copyMemory(long srcAddress, long destAddress, long bytes) {
458 copyMemory(null, srcAddress, null, destAddress, bytes);
459 }
460
461 /**
462 * Copies all elements from one block of memory to another block, byte swapping the
463 * elements on the fly.
464 *
465 * <p>This method determines each block's base address by means of two parameters,
466 * and so it provides (in effect) a <em>double-register</em> addressing mode,
467 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
468 * the offset supplies an absolute base address.
469 *
470 * @since 9
471 */
472 public native void copySwapMemory(Object srcBase, long srcOffset,
473 Object destBase, long destOffset,
474 long bytes, long elemSize);
475
476 /**
477 * Copies all elements from one block of memory to another block, byte swapping the
478 * elements on the fly.
479 *
480 * This provides a <em>single-register</em> addressing mode, as
481 * discussed in {@link #getInt(Object,long)}.
482 *
483 * Equivalent to {@code copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize)}.
484 */
485 public void copySwapMemory(long srcAddress, long destAddress, long bytes, long elemSize) {
486 copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize);
487 }
488
489 /**
490 * Disposes of a block of native memory, as obtained from {@link
491 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
492 * this method may be null, in which case no action is taken.
493 *
494 * @see #allocateMemory
495 */
496 public native void freeMemory(long address);
497
498 /// random queries
499
500 /**
501 * This constant differs from all results that will ever be returned from
502 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
503 * or {@link #arrayBaseOffset}.
504 */
505 public static final int INVALID_FIELD_OFFSET = -1;
506
507 /**
508 * Reports the location of a given field in the storage allocation of its
509 * class. Do not expect to perform any sort of arithmetic on this offset;
510 * it is just a cookie which is passed to the unsafe heap memory accessors.
511 *
512 * <p>Any given field will always have the same offset and base, and no
513 * two distinct fields of the same class will ever have the same offset
514 * and base.
515 *
516 * <p>As of 1.4.1, offsets for fields are represented as long values,
517 * although the Sun JVM does not use the most significant 32 bits.
518 * However, JVM implementations which store static fields at absolute
519 * addresses can use long offsets and null base pointers to express
520 * the field locations in a form usable by {@link #getInt(Object,long)}.
521 * Therefore, code which will be ported to such JVMs on 64-bit platforms
522 * must preserve all bits of static field offsets.
523 * @see #getInt(Object, long)
524 */
525 public native long objectFieldOffset(Field f);
526
527 /**
528 * Reports the location of a given static field, in conjunction with {@link
529 * #staticFieldBase}.
530 * <p>Do not expect to perform any sort of arithmetic on this offset;
531 * it is just a cookie which is passed to the unsafe heap memory accessors.
532 *
533 * <p>Any given field will always have the same offset, and no two distinct
534 * fields of the same class will ever have the same offset.
535 *
536 * <p>As of 1.4.1, offsets for fields are represented as long values,
537 * although the Sun JVM does not use the most significant 32 bits.
538 * It is hard to imagine a JVM technology which needs more than
539 * a few bits to encode an offset within a non-array object,
540 * However, for consistency with other methods in this class,
541 * this method reports its result as a long value.
542 * @see #getInt(Object, long)
543 */
544 public native long staticFieldOffset(Field f);
545
546 /**
547 * Reports the location of a given static field, in conjunction with {@link
548 * #staticFieldOffset}.
549 * <p>Fetch the base "Object", if any, with which static fields of the
550 * given class can be accessed via methods like {@link #getInt(Object,
551 * long)}. This value may be null. This value may refer to an object
552 * which is a "cookie", not guaranteed to be a real Object, and it should
553 * not be used in any way except as argument to the get and put routines in
554 * this class.
555 */
556 public native Object staticFieldBase(Field f);
557
558 /**
559 * Detects if the given class may need to be initialized. This is often
560 * needed in conjunction with obtaining the static field base of a
561 * class.
562 * @return false only if a call to {@code ensureClassInitialized} would have no effect
563 */
564 public native boolean shouldBeInitialized(Class<?> c);
565
566 /**
567 * Ensures the given class has been initialized. This is often
568 * needed in conjunction with obtaining the static field base of a
569 * class.
570 */
571 public native void ensureClassInitialized(Class<?> c);
572
573 /**
574 * Reports the offset of the first element in the storage allocation of a
575 * given array class. If {@link #arrayIndexScale} returns a non-zero value
576 * for the same class, you may use that scale factor, together with this
577 * base offset, to form new offsets to access elements of arrays of the
578 * given class.
579 *
580 * @see #getInt(Object, long)
581 * @see #putInt(Object, long, int)
582 */
583 public native int arrayBaseOffset(Class<?> arrayClass);
584
585 /** The value of {@code arrayBaseOffset(boolean[].class)} */
586 public static final int ARRAY_BOOLEAN_BASE_OFFSET
587 = theUnsafe.arrayBaseOffset(boolean[].class);
588
589 /** The value of {@code arrayBaseOffset(byte[].class)} */
590 public static final int ARRAY_BYTE_BASE_OFFSET
591 = theUnsafe.arrayBaseOffset(byte[].class);
592
593 /** The value of {@code arrayBaseOffset(short[].class)} */
594 public static final int ARRAY_SHORT_BASE_OFFSET
595 = theUnsafe.arrayBaseOffset(short[].class);
596
597 /** The value of {@code arrayBaseOffset(char[].class)} */
598 public static final int ARRAY_CHAR_BASE_OFFSET
599 = theUnsafe.arrayBaseOffset(char[].class);
600
601 /** The value of {@code arrayBaseOffset(int[].class)} */
602 public static final int ARRAY_INT_BASE_OFFSET
603 = theUnsafe.arrayBaseOffset(int[].class);
604
605 /** The value of {@code arrayBaseOffset(long[].class)} */
606 public static final int ARRAY_LONG_BASE_OFFSET
607 = theUnsafe.arrayBaseOffset(long[].class);
608
609 /** The value of {@code arrayBaseOffset(float[].class)} */
610 public static final int ARRAY_FLOAT_BASE_OFFSET
611 = theUnsafe.arrayBaseOffset(float[].class);
612
613 /** The value of {@code arrayBaseOffset(double[].class)} */
614 public static final int ARRAY_DOUBLE_BASE_OFFSET
615 = theUnsafe.arrayBaseOffset(double[].class);
616
617 /** The value of {@code arrayBaseOffset(Object[].class)} */
618 public static final int ARRAY_OBJECT_BASE_OFFSET
619 = theUnsafe.arrayBaseOffset(Object[].class);
620
621 /**
622 * Reports the scale factor for addressing elements in the storage
623 * allocation of a given array class. However, arrays of "narrow" types
624 * will generally not work properly with accessors like {@link
625 * #getByte(Object, long)}, so the scale factor for such classes is reported
626 * as zero.
627 *
628 * @see #arrayBaseOffset
629 * @see #getInt(Object, long)
630 * @see #putInt(Object, long, int)
631 */
632 public native int arrayIndexScale(Class<?> arrayClass);
633
634 /** The value of {@code arrayIndexScale(boolean[].class)} */
635 public static final int ARRAY_BOOLEAN_INDEX_SCALE
636 = theUnsafe.arrayIndexScale(boolean[].class);
637
638 /** The value of {@code arrayIndexScale(byte[].class)} */
639 public static final int ARRAY_BYTE_INDEX_SCALE
640 = theUnsafe.arrayIndexScale(byte[].class);
641
642 /** The value of {@code arrayIndexScale(short[].class)} */
643 public static final int ARRAY_SHORT_INDEX_SCALE
644 = theUnsafe.arrayIndexScale(short[].class);
645
646 /** The value of {@code arrayIndexScale(char[].class)} */
647 public static final int ARRAY_CHAR_INDEX_SCALE
648 = theUnsafe.arrayIndexScale(char[].class);
649
650 /** The value of {@code arrayIndexScale(int[].class)} */
651 public static final int ARRAY_INT_INDEX_SCALE
652 = theUnsafe.arrayIndexScale(int[].class);
653
654 /** The value of {@code arrayIndexScale(long[].class)} */
655 public static final int ARRAY_LONG_INDEX_SCALE
656 = theUnsafe.arrayIndexScale(long[].class);
657
658 /** The value of {@code arrayIndexScale(float[].class)} */
659 public static final int ARRAY_FLOAT_INDEX_SCALE
660 = theUnsafe.arrayIndexScale(float[].class);
661
662 /** The value of {@code arrayIndexScale(double[].class)} */
663 public static final int ARRAY_DOUBLE_INDEX_SCALE
664 = theUnsafe.arrayIndexScale(double[].class);
665
666 /** The value of {@code arrayIndexScale(Object[].class)} */
667 public static final int ARRAY_OBJECT_INDEX_SCALE
668 = theUnsafe.arrayIndexScale(Object[].class);
669
670 /**
671 * Reports the size in bytes of a native pointer, as stored via {@link
672 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
673 * other primitive types (as stored in native memory blocks) is determined
674 * fully by their information content.
675 */
676 public native int addressSize();
677
678 /** The value of {@code addressSize()} */
679 public static final int ADDRESS_SIZE = theUnsafe.addressSize();
680
681 /**
682 * Reports the size in bytes of a native memory page (whatever that is).
683 * This value will always be a power of two.
684 */
685 public native int pageSize();
686
687
688 /// random trusted operations from JNI:
689
690 /**
691 * Tells the VM to define a class, without security checks. By default, the
692 * class loader and protection domain come from the caller's class.
693 */
694 public native Class<?> defineClass(String name, byte[] b, int off, int len,
695 ClassLoader loader,
696 ProtectionDomain protectionDomain);
697
698 /**
699 * Defines a class but does not make it known to the class loader or system dictionary.
700 * <p>
701 * For each CP entry, the corresponding CP patch must either be null or have
702 * the a format that matches its tag:
703 * <ul>
704 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
705 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
706 * <li>Class: any java.lang.Class object
707 * <li>String: any object (not just a java.lang.String)
708 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
709 * </ul>
710 * @param hostClass context for linkage, access control, protection domain, and class loader
711 * @param data bytes of a class file
712 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
713 */
714 public native Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches);
715
716 /**
717 * Allocates an instance but does not run any constructor.
718 * Initializes the class if it has not yet been.
719 */
720 @HotSpotIntrinsicCandidate
721 public native Object allocateInstance(Class<?> cls)
722 throws InstantiationException;
723
724 /** Throws the exception without telling the verifier. */
725 public native void throwException(Throwable ee);
726
727 /**
728 * Atomically updates Java variable to {@code x} if it is currently
729 * holding {@code expected}.
730 *
731 * <p>This operation has memory semantics of a {@code volatile} read
732 * and write. Corresponds to C11 atomic_compare_exchange_strong.
733 *
734 * @return {@code true} if successful
735 */
736 @HotSpotIntrinsicCandidate
737 public final native boolean compareAndSwapObject(Object o, long offset,
738 Object expected,
739 Object x);
740
741 /**
742 * Atomically updates Java variable to {@code x} if it is currently
743 * holding {@code expected}.
744 *
745 * <p>This operation has memory semantics of a {@code volatile} read
746 * and write. Corresponds to C11 atomic_compare_exchange_strong.
747 *
748 * @return {@code true} if successful
749 */
750 @HotSpotIntrinsicCandidate
751 public final native boolean compareAndSwapInt(Object o, long offset,
752 int expected,
753 int x);
754
755 /**
756 * Atomically updates Java variable to {@code x} if it is currently
757 * holding {@code expected}.
758 *
759 * <p>This operation has memory semantics of a {@code volatile} read
760 * and write. Corresponds to C11 atomic_compare_exchange_strong.
761 *
762 * @return {@code true} if successful
763 */
764 @HotSpotIntrinsicCandidate
765 public final native boolean compareAndSwapLong(Object o, long offset,
766 long expected,
767 long x);
768
769 /**
770 * Fetches a reference value from a given Java variable, with volatile
771 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
772 */
773 @HotSpotIntrinsicCandidate
774 public native Object getObjectVolatile(Object o, long offset);
775
776 /**
777 * Stores a reference value into a given Java variable, with
778 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
779 */
780 @HotSpotIntrinsicCandidate
781 public native void putObjectVolatile(Object o, long offset, Object x);
782
783 /** Volatile version of {@link #getInt(Object, long)} */
784 @HotSpotIntrinsicCandidate
785 public native int getIntVolatile(Object o, long offset);
786
787 /** Volatile version of {@link #putInt(Object, long, int)} */
788 @HotSpotIntrinsicCandidate
789 public native void putIntVolatile(Object o, long offset, int x);
790
791 /** Volatile version of {@link #getBoolean(Object, long)} */
792 @HotSpotIntrinsicCandidate
793 public native boolean getBooleanVolatile(Object o, long offset);
794
795 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
796 @HotSpotIntrinsicCandidate
797 public native void putBooleanVolatile(Object o, long offset, boolean x);
798
799 /** Volatile version of {@link #getByte(Object, long)} */
800 @HotSpotIntrinsicCandidate
801 public native byte getByteVolatile(Object o, long offset);
802
803 /** Volatile version of {@link #putByte(Object, long, byte)} */
804 @HotSpotIntrinsicCandidate
805 public native void putByteVolatile(Object o, long offset, byte x);
806
807 /** Volatile version of {@link #getShort(Object, long)} */
808 @HotSpotIntrinsicCandidate
809 public native short getShortVolatile(Object o, long offset);
810
811 /** Volatile version of {@link #putShort(Object, long, short)} */
812 @HotSpotIntrinsicCandidate
813 public native void putShortVolatile(Object o, long offset, short x);
814
815 /** Volatile version of {@link #getChar(Object, long)} */
816 @HotSpotIntrinsicCandidate
817 public native char getCharVolatile(Object o, long offset);
818
819 /** Volatile version of {@link #putChar(Object, long, char)} */
820 @HotSpotIntrinsicCandidate
821 public native void putCharVolatile(Object o, long offset, char x);
822
823 /** Volatile version of {@link #getLong(Object, long)} */
824 @HotSpotIntrinsicCandidate
825 public native long getLongVolatile(Object o, long offset);
826
827 /** Volatile version of {@link #putLong(Object, long, long)} */
828 @HotSpotIntrinsicCandidate
829 public native void putLongVolatile(Object o, long offset, long x);
830
831 /** Volatile version of {@link #getFloat(Object, long)} */
832 @HotSpotIntrinsicCandidate
833 public native float getFloatVolatile(Object o, long offset);
834
835 /** Volatile version of {@link #putFloat(Object, long, float)} */
836 @HotSpotIntrinsicCandidate
837 public native void putFloatVolatile(Object o, long offset, float x);
838
839 /** Volatile version of {@link #getDouble(Object, long)} */
840 @HotSpotIntrinsicCandidate
841 public native double getDoubleVolatile(Object o, long offset);
842
843 /** Volatile version of {@link #putDouble(Object, long, double)} */
844 @HotSpotIntrinsicCandidate
845 public native void putDoubleVolatile(Object o, long offset, double x);
846
847 /**
848 * Version of {@link #putObjectVolatile(Object, long, Object)}
849 * that does not guarantee immediate visibility of the store to
850 * other threads. This method is generally only useful if the
851 * underlying field is a Java volatile (or if an array cell, one
852 * that is otherwise only accessed using volatile accesses).
853 *
854 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
855 */
856 @HotSpotIntrinsicCandidate
857 public native void putOrderedObject(Object o, long offset, Object x);
858
859 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
860 @HotSpotIntrinsicCandidate
861 public native void putOrderedInt(Object o, long offset, int x);
862
863 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
864 @HotSpotIntrinsicCandidate
865 public native void putOrderedLong(Object o, long offset, long x);
866
867 /**
868 * Unblocks the given thread blocked on {@code park}, or, if it is
869 * not blocked, causes the subsequent call to {@code park} not to
870 * block. Note: this operation is "unsafe" solely because the
871 * caller must somehow ensure that the thread has not been
872 * destroyed. Nothing special is usually required to ensure this
873 * when called from Java (in which there will ordinarily be a live
874 * reference to the thread) but this is not nearly-automatically
875 * so when calling from native code.
876 *
877 * @param thread the thread to unpark.
878 */
879 @HotSpotIntrinsicCandidate
880 public native void unpark(Object thread);
881
882 /**
883 * Blocks current thread, returning when a balancing
884 * {@code unpark} occurs, or a balancing {@code unpark} has
885 * already occurred, or the thread is interrupted, or, if not
886 * absolute and time is not zero, the given time nanoseconds have
887 * elapsed, or if absolute, the given deadline in milliseconds
888 * since Epoch has passed, or spuriously (i.e., returning for no
889 * "reason"). Note: This operation is in the Unsafe class only
890 * because {@code unpark} is, so it would be strange to place it
891 * elsewhere.
892 */
893 @HotSpotIntrinsicCandidate
894 public native void park(boolean isAbsolute, long time);
895
896 /**
897 * Gets the load average in the system run queue assigned
898 * to the available processors averaged over various periods of time.
899 * This method retrieves the given {@code nelem} samples and
900 * assigns to the elements of the given {@code loadavg} array.
901 * The system imposes a maximum of 3 samples, representing
902 * averages over the last 1, 5, and 15 minutes, respectively.
903 *
904 * @param loadavg an array of double of size nelems
905 * @param nelems the number of samples to be retrieved and
906 * must be 1 to 3.
907 *
908 * @return the number of samples actually retrieved; or -1
909 * if the load average is unobtainable.
910 */
911 public native int getLoadAverage(double[] loadavg, int nelems);
912
913 // The following contain CAS-based Java implementations used on
914 // platforms not supporting native instructions
915
916 /**
917 * Atomically adds the given value to the current value of a field
918 * or array element within the given object {@code o}
919 * at the given {@code offset}.
920 *
921 * @param o object/array to update the field/element in
922 * @param offset field/element offset
923 * @param delta the value to add
924 * @return the previous value
925 * @since 1.8
926 */
927 @HotSpotIntrinsicCandidate
928 public final int getAndAddInt(Object o, long offset, int delta) {
929 int v;
930 do {
931 v = getIntVolatile(o, offset);
932 } while (!compareAndSwapInt(o, offset, v, v + delta));
933 return v;
934 }
935
936 /**
937 * Atomically adds the given value to the current value of a field
938 * or array element within the given object {@code o}
939 * at the given {@code offset}.
940 *
941 * @param o object/array to update the field/element in
942 * @param offset field/element offset
943 * @param delta the value to add
944 * @return the previous value
945 * @since 1.8
946 */
947 @HotSpotIntrinsicCandidate
948 public final long getAndAddLong(Object o, long offset, long delta) {
949 long v;
950 do {
951 v = getLongVolatile(o, offset);
952 } while (!compareAndSwapLong(o, offset, v, v + delta));
953 return v;
954 }
955
956 /**
957 * Atomically exchanges the given value with the current value of
958 * a field or array element within the given object {@code o}
959 * at the given {@code offset}.
960 *
961 * @param o object/array to update the field/element in
962 * @param offset field/element offset
963 * @param newValue new value
964 * @return the previous value
965 * @since 1.8
966 */
967 @HotSpotIntrinsicCandidate
968 public final int getAndSetInt(Object o, long offset, int newValue) {
969 int v;
970 do {
971 v = getIntVolatile(o, offset);
972 } while (!compareAndSwapInt(o, offset, v, newValue));
973 return v;
974 }
975
976 /**
977 * Atomically exchanges the given value with the current value of
978 * a field or array element within the given object {@code o}
979 * at the given {@code offset}.
980 *
981 * @param o object/array to update the field/element in
982 * @param offset field/element offset
983 * @param newValue new value
984 * @return the previous value
985 * @since 1.8
986 */
987 @HotSpotIntrinsicCandidate
988 public final long getAndSetLong(Object o, long offset, long newValue) {
989 long v;
990 do {
991 v = getLongVolatile(o, offset);
992 } while (!compareAndSwapLong(o, offset, v, newValue));
993 return v;
994 }
995
996 /**
997 * Atomically exchanges the given reference value with the current
998 * reference value of a field or array element within the given
999 * object {@code o} at the given {@code offset}.
1000 *
1001 * @param o object/array to update the field/element in
1002 * @param offset field/element offset
1003 * @param newValue new value
1004 * @return the previous value
1005 * @since 1.8
1006 */
1007 @HotSpotIntrinsicCandidate
1008 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1009 Object v;
1010 do {
1011 v = getObjectVolatile(o, offset);
1012 } while (!compareAndSwapObject(o, offset, v, newValue));
1013 return v;
1014 }
1015
1016
1017 /**
1018 * Ensures that loads before the fence will not be reordered with loads and
1019 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1020 *
1021 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1022 * (an "acquire fence").
1023 *
1024 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1025 * is almost always desired, and most current hardware instructions that
1026 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1027 * @since 1.8
1028 */
1029 @HotSpotIntrinsicCandidate
1030 public native void loadFence();
1031
1032 /**
1033 * Ensures that loads and stores before the fence will not be reordered with
1034 * stores after the fence; a "StoreStore plus LoadStore barrier".
1035 *
1036 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1037 * (a "release fence").
1038 *
1039 * A pure StoreStore fence is not provided, since the addition of LoadStore
1040 * is almost always desired, and most current hardware instructions that
1041 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1042 * @since 1.8
1043 */
1044 @HotSpotIntrinsicCandidate
1045 public native void storeFence();
1046
1047 /**
1048 * Ensures that loads and stores before the fence will not be reordered
1049 * with loads and stores after the fence. Implies the effects of both
1050 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1051 * barrier.
1052 *
1053 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1054 * @since 1.8
1055 */
1056 @HotSpotIntrinsicCandidate
1057 public native void fullFence();
1058
1059 /**
1060 * Throws IllegalAccessError; for use by the VM for access control
1061 * error support.
1062 * @since 1.8
1063 */
1064 private static void throwIllegalAccessError() {
1065 throw new IllegalAccessError();
1066 }
1067
1068 /**
1069 * @return Returns true if the native byte ordering of this
1070 * platform is big-endian, false if it is little-endian.
1071 */
1072 public final boolean isBigEndian() { return BE; }
1073
1074 /**
1075 * @return Returns true if this platform is capable of performing
1076 * accesses at addresses which are not aligned for the type of the
1077 * primitive type being accessed, false otherwise.
1078 */
1079 public final boolean unalignedAccess() { return unalignedAccess; }
1080
1081 /**
1082 * Fetches a value at some byte offset into a given Java object.
1083 * More specifically, fetches a value within the given object
1084 * <code>o</code> at the given offset, or (if <code>o</code> is
1085 * null) from the memory address whose numerical value is the
1086 * given offset. <p>
1087 *
1088 * The specification of this method is the same as {@link
1089 * #getLong(Object, long)} except that the offset does not need to
1090 * have been obtained from {@link #objectFieldOffset} on the
1091 * {@link java.lang.reflect.Field} of some Java field. The value
1092 * in memory is raw data, and need not correspond to any Java
1093 * variable. Unless <code>o</code> is null, the value accessed
1094 * must be entirely within the allocated object. The endianness
1095 * of the value in memory is the endianness of the native platform.
1096 *
1097 * <p> The read will be atomic with respect to the largest power
1098 * of two that divides the GCD of the offset and the storage size.
1099 * For example, getLongUnaligned will make atomic reads of 2-, 4-,
1100 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1101 * respectively. There are no other guarantees of atomicity.
1102 * <p>
1103 * 8-byte atomicity is only guaranteed on platforms on which
1104 * support atomic accesses to longs.
1105 *
1106 * @param o Java heap object in which the value resides, if any, else
1107 * null
1108 * @param offset The offset in bytes from the start of the object
1109 * @return the value fetched from the indicated object
1110 * @throws RuntimeException No defined exceptions are thrown, not even
1111 * {@link NullPointerException}
1112 * @since 9
1113 */
1114 @HotSpotIntrinsicCandidate
1115 public final long getLongUnaligned(Object o, long offset) {
1116 if ((offset & 7) == 0) {
1117 return getLong(o, offset);
1118 } else if ((offset & 3) == 0) {
1119 return makeLong(getInt(o, offset),
1120 getInt(o, offset + 4));
1121 } else if ((offset & 1) == 0) {
1122 return makeLong(getShort(o, offset),
1123 getShort(o, offset + 2),
1124 getShort(o, offset + 4),
1125 getShort(o, offset + 6));
1126 } else {
1127 return makeLong(getByte(o, offset),
1128 getByte(o, offset + 1),
1129 getByte(o, offset + 2),
1130 getByte(o, offset + 3),
1131 getByte(o, offset + 4),
1132 getByte(o, offset + 5),
1133 getByte(o, offset + 6),
1134 getByte(o, offset + 7));
1135 }
1136 }
1137 /**
1138 * As {@link #getLongUnaligned(Object, long)} but with an
1139 * additional argument which specifies the endianness of the value
1140 * as stored in memory.
1141 *
1142 * @param o Java heap object in which the variable resides
1143 * @param offset The offset in bytes from the start of the object
1144 * @param bigEndian The endianness of the value
1145 * @return the value fetched from the indicated object
1146 * @since 9
1147 */
1148 public final long getLongUnaligned(Object o, long offset, boolean bigEndian) {
1149 return convEndian(bigEndian, getLongUnaligned(o, offset));
1150 }
1151
1152 /** @see #getLongUnaligned(Object, long) */
1153 @HotSpotIntrinsicCandidate
1154 public final int getIntUnaligned(Object o, long offset) {
1155 if ((offset & 3) == 0) {
1156 return getInt(o, offset);
1157 } else if ((offset & 1) == 0) {
1158 return makeInt(getShort(o, offset),
1159 getShort(o, offset + 2));
1160 } else {
1161 return makeInt(getByte(o, offset),
1162 getByte(o, offset + 1),
1163 getByte(o, offset + 2),
1164 getByte(o, offset + 3));
1165 }
1166 }
1167 /** @see #getLongUnaligned(Object, long, boolean) */
1168 public final int getIntUnaligned(Object o, long offset, boolean bigEndian) {
1169 return convEndian(bigEndian, getIntUnaligned(o, offset));
1170 }
1171
1172 /** @see #getLongUnaligned(Object, long) */
1173 @HotSpotIntrinsicCandidate
1174 public final short getShortUnaligned(Object o, long offset) {
1175 if ((offset & 1) == 0) {
1176 return getShort(o, offset);
1177 } else {
1178 return makeShort(getByte(o, offset),
1179 getByte(o, offset + 1));
1180 }
1181 }
1182 /** @see #getLongUnaligned(Object, long, boolean) */
1183 public final short getShortUnaligned(Object o, long offset, boolean bigEndian) {
1184 return convEndian(bigEndian, getShortUnaligned(o, offset));
1185 }
1186
1187 /** @see #getLongUnaligned(Object, long) */
1188 @HotSpotIntrinsicCandidate
1189 public final char getCharUnaligned(Object o, long offset) {
1190 return (char)getShortUnaligned(o, offset);
1191 }
1192
1193 /** @see #getLongUnaligned(Object, long, boolean) */
1194 public final char getCharUnaligned(Object o, long offset, boolean bigEndian) {
1195 return convEndian(bigEndian, getCharUnaligned(o, offset));
1196 }
1197
1198 /**
1199 * Stores a value at some byte offset into a given Java object.
1200 * <p>
1201 * The specification of this method is the same as {@link
1202 * #getLong(Object, long)} except that the offset does not need to
1203 * have been obtained from {@link #objectFieldOffset} on the
1204 * {@link java.lang.reflect.Field} of some Java field. The value
1205 * in memory is raw data, and need not correspond to any Java
1206 * variable. The endianness of the value in memory is the
1207 * endianness of the native platform.
1208 * <p>
1209 * The write will be atomic with respect to the largest power of
1210 * two that divides the GCD of the offset and the storage size.
1211 * For example, putLongUnaligned will make atomic writes of 2-, 4-,
1212 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1213 * respectively. There are no other guarantees of atomicity.
1214 * <p>
1215 * 8-byte atomicity is only guaranteed on platforms on which
1216 * support atomic accesses to longs.
1217 *
1218 * @param o Java heap object in which the value resides, if any, else
1219 * null
1220 * @param offset The offset in bytes from the start of the object
1221 * @param x the value to store
1222 * @throws RuntimeException No defined exceptions are thrown, not even
1223 * {@link NullPointerException}
1224 * @since 9
1225 */
1226 @HotSpotIntrinsicCandidate
1227 public final void putLongUnaligned(Object o, long offset, long x) {
1228 if ((offset & 7) == 0) {
1229 putLong(o, offset, x);
1230 } else if ((offset & 3) == 0) {
1231 putLongParts(o, offset,
1232 (int)(x >> 0),
1233 (int)(x >>> 32));
1234 } else if ((offset & 1) == 0) {
1235 putLongParts(o, offset,
1236 (short)(x >>> 0),
1237 (short)(x >>> 16),
1238 (short)(x >>> 32),
1239 (short)(x >>> 48));
1240 } else {
1241 putLongParts(o, offset,
1242 (byte)(x >>> 0),
1243 (byte)(x >>> 8),
1244 (byte)(x >>> 16),
1245 (byte)(x >>> 24),
1246 (byte)(x >>> 32),
1247 (byte)(x >>> 40),
1248 (byte)(x >>> 48),
1249 (byte)(x >>> 56));
1250 }
1251 }
1252
1253 /**
1254 * As {@link #putLongUnaligned(Object, long, long)} but with an additional
1255 * argument which specifies the endianness of the value as stored in memory.
1256 * @param o Java heap object in which the value resides
1257 * @param offset The offset in bytes from the start of the object
1258 * @param x the value to store
1259 * @param bigEndian The endianness of the value
1260 * @throws RuntimeException No defined exceptions are thrown, not even
1261 * {@link NullPointerException}
1262 * @since 9
1263 */
1264 public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) {
1265 putLongUnaligned(o, offset, convEndian(bigEndian, x));
1266 }
1267
1268 /** @see #putLongUnaligned(Object, long, long) */
1269 @HotSpotIntrinsicCandidate
1270 public final void putIntUnaligned(Object o, long offset, int x) {
1271 if ((offset & 3) == 0) {
1272 putInt(o, offset, x);
1273 } else if ((offset & 1) == 0) {
1274 putIntParts(o, offset,
1275 (short)(x >> 0),
1276 (short)(x >>> 16));
1277 } else {
1278 putIntParts(o, offset,
1279 (byte)(x >>> 0),
1280 (byte)(x >>> 8),
1281 (byte)(x >>> 16),
1282 (byte)(x >>> 24));
1283 }
1284 }
1285 /** @see #putLongUnaligned(Object, long, long, boolean) */
1286 public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) {
1287 putIntUnaligned(o, offset, convEndian(bigEndian, x));
1288 }
1289
1290 /** @see #putLongUnaligned(Object, long, long) */
1291 @HotSpotIntrinsicCandidate
1292 public final void putShortUnaligned(Object o, long offset, short x) {
1293 if ((offset & 1) == 0) {
1294 putShort(o, offset, x);
1295 } else {
1296 putShortParts(o, offset,
1297 (byte)(x >>> 0),
1298 (byte)(x >>> 8));
1299 }
1300 }
1301 /** @see #putLongUnaligned(Object, long, long, boolean) */
1302 public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) {
1303 putShortUnaligned(o, offset, convEndian(bigEndian, x));
1304 }
1305
1306 /** @see #putLongUnaligned(Object, long, long) */
1307 @HotSpotIntrinsicCandidate
1308 public final void putCharUnaligned(Object o, long offset, char x) {
1309 putShortUnaligned(o, offset, (short)x);
1310 }
1311 /** @see #putLongUnaligned(Object, long, long, boolean) */
1312 public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) {
1313 putCharUnaligned(o, offset, convEndian(bigEndian, x));
1314 }
1315
1316 // JVM interface methods
1317 private native boolean unalignedAccess0();
1318 private native boolean isBigEndian0();
1319
1320 // BE is true iff the native endianness of this platform is big.
1321 private static final boolean BE = theUnsafe.isBigEndian0();
1322
1323 // unalignedAccess is true iff this platform can perform unaligned accesses.
1324 private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
1325
1326 private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
1327
1328 // These methods construct integers from bytes. The byte ordering
1329 // is the native endianness of this platform.
1330 private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
1331 return ((toUnsignedLong(i0) << pickPos(56, 0))
1332 | (toUnsignedLong(i1) << pickPos(56, 8))
1333 | (toUnsignedLong(i2) << pickPos(56, 16))
1334 | (toUnsignedLong(i3) << pickPos(56, 24))
1335 | (toUnsignedLong(i4) << pickPos(56, 32))
1336 | (toUnsignedLong(i5) << pickPos(56, 40))
1337 | (toUnsignedLong(i6) << pickPos(56, 48))
1338 | (toUnsignedLong(i7) << pickPos(56, 56)));
1339 }
1340 private static long makeLong(short i0, short i1, short i2, short i3) {
1341 return ((toUnsignedLong(i0) << pickPos(48, 0))
1342 | (toUnsignedLong(i1) << pickPos(48, 16))
1343 | (toUnsignedLong(i2) << pickPos(48, 32))
1344 | (toUnsignedLong(i3) << pickPos(48, 48)));
1345 }
1346 private static long makeLong(int i0, int i1) {
1347 return (toUnsignedLong(i0) << pickPos(32, 0))
1348 | (toUnsignedLong(i1) << pickPos(32, 32));
1349 }
1350 private static int makeInt(short i0, short i1) {
1351 return (toUnsignedInt(i0) << pickPos(16, 0))
1352 | (toUnsignedInt(i1) << pickPos(16, 16));
1353 }
1354 private static int makeInt(byte i0, byte i1, byte i2, byte i3) {
1355 return ((toUnsignedInt(i0) << pickPos(24, 0))
1356 | (toUnsignedInt(i1) << pickPos(24, 8))
1357 | (toUnsignedInt(i2) << pickPos(24, 16))
1358 | (toUnsignedInt(i3) << pickPos(24, 24)));
1359 }
1360 private static short makeShort(byte i0, byte i1) {
1361 return (short)((toUnsignedInt(i0) << pickPos(8, 0))
1362 | (toUnsignedInt(i1) << pickPos(8, 8)));
1363 }
1364
1365 private static byte pick(byte le, byte be) { return BE ? be : le; }
1366 private static short pick(short le, short be) { return BE ? be : le; }
1367 private static int pick(int le, int be) { return BE ? be : le; }
1368
1369 // These methods write integers to memory from smaller parts
1370 // provided by their caller. The ordering in which these parts
1371 // are written is the native endianness of this platform.
1372 private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
1373 putByte(o, offset + 0, pick(i0, i7));
1374 putByte(o, offset + 1, pick(i1, i6));
1375 putByte(o, offset + 2, pick(i2, i5));
1376 putByte(o, offset + 3, pick(i3, i4));
1377 putByte(o, offset + 4, pick(i4, i3));
1378 putByte(o, offset + 5, pick(i5, i2));
1379 putByte(o, offset + 6, pick(i6, i1));
1380 putByte(o, offset + 7, pick(i7, i0));
1381 }
1382 private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) {
1383 putShort(o, offset + 0, pick(i0, i3));
1384 putShort(o, offset + 2, pick(i1, i2));
1385 putShort(o, offset + 4, pick(i2, i1));
1386 putShort(o, offset + 6, pick(i3, i0));
1387 }
1388 private void putLongParts(Object o, long offset, int i0, int i1) {
1389 putInt(o, offset + 0, pick(i0, i1));
1390 putInt(o, offset + 4, pick(i1, i0));
1391 }
1392 private void putIntParts(Object o, long offset, short i0, short i1) {
1393 putShort(o, offset + 0, pick(i0, i1));
1394 putShort(o, offset + 2, pick(i1, i0));
1395 }
1396 private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) {
1397 putByte(o, offset + 0, pick(i0, i3));
1398 putByte(o, offset + 1, pick(i1, i2));
1399 putByte(o, offset + 2, pick(i2, i1));
1400 putByte(o, offset + 3, pick(i3, i0));
1401 }
1402 private void putShortParts(Object o, long offset, byte i0, byte i1) {
1403 putByte(o, offset + 0, pick(i0, i1));
1404 putByte(o, offset + 1, pick(i1, i0));
1405 }
1406
1407 // Zero-extend an integer
1408 private static int toUnsignedInt(byte n) { return n & 0xff; }
1409 private static int toUnsignedInt(short n) { return n & 0xffff; }
1410 private static long toUnsignedLong(byte n) { return n & 0xffl; }
1411 private static long toUnsignedLong(short n) { return n & 0xffffl; }
1412 private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
1413
1414 // Maybe byte-reverse an integer
1415 private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
1416 private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
1417 private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
1418 private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
1419 }