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 private boolean isPrimitiveArray(Class<?> c) {
462 Class<?> componentType = c.getComponentType();
463 return componentType != null && componentType.isPrimitive();
464 }
465
466 private native void copySwapMemory0(Object srcBase, long srcOffset,
467 Object destBase, long destOffset,
468 long bytes, long elemSize);
469
470 /**
471 * Copies all elements from one block of memory to another block,
472 * *unconditionally* byte swapping the elements on the fly.
473 *
474 * <p>This method determines each block's base address by means of two parameters,
475 * and so it provides (in effect) a <em>double-register</em> addressing mode,
476 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
477 * the offset supplies an absolute base address.
478 *
479 * @since 9
480 */
481 public void copySwapMemory(Object srcBase, long srcOffset,
482 Object destBase, long destOffset,
483 long bytes, long elemSize) {
484 if (bytes < 0) {
485 throw new IllegalArgumentException();
486 }
487 if (elemSize != 2 && elemSize != 4 && elemSize != 8) {
488 throw new IllegalArgumentException();
489 }
490 if (bytes % elemSize != 0) {
491 throw new IllegalArgumentException();
492 }
493 if ((srcBase == null && srcOffset == 0) ||
494 (destBase == null && destOffset == 0)) {
495 throw new NullPointerException();
496 }
497
498 // Must be off-heap, or primitive heap arrays
499 if (srcBase != null && (srcOffset < 0 || !isPrimitiveArray(srcBase.getClass()))) {
500 throw new IllegalArgumentException();
501 }
502 if (destBase != null && (destOffset < 0 || !isPrimitiveArray(destBase.getClass()))) {
503 throw new IllegalArgumentException();
504 }
505
506 // Sanity check size and offsets on 32-bit platforms. Most
507 // significant 32 bits must be zero.
508 if (ADDRESS_SIZE == 4 &&
509 (bytes >>> 32 != 0 || srcOffset >>> 32 != 0 || destOffset >>> 32 != 0)) {
510 throw new IllegalArgumentException();
511 }
512
513 if (bytes == 0) {
514 return;
515 }
516
517 copySwapMemory0(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
518 }
519
520 /**
521 * Copies all elements from one block of memory to another block, byte swapping the
522 * elements on the fly.
523 *
524 * This provides a <em>single-register</em> addressing mode, as
525 * discussed in {@link #getInt(Object,long)}.
526 *
527 * Equivalent to {@code copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize)}.
528 */
529 public void copySwapMemory(long srcAddress, long destAddress, long bytes, long elemSize) {
530 copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize);
531 }
532
533 /**
534 * Disposes of a block of native memory, as obtained from {@link
535 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
536 * this method may be null, in which case no action is taken.
537 *
538 * @see #allocateMemory
539 */
540 public native void freeMemory(long address);
541
542 /// random queries
543
544 /**
545 * This constant differs from all results that will ever be returned from
546 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
547 * or {@link #arrayBaseOffset}.
548 */
549 public static final int INVALID_FIELD_OFFSET = -1;
550
551 /**
552 * Reports the location of a given field in the storage allocation of its
553 * class. Do not expect to perform any sort of arithmetic on this offset;
554 * it is just a cookie which is passed to the unsafe heap memory accessors.
555 *
556 * <p>Any given field will always have the same offset and base, and no
557 * two distinct fields of the same class will ever have the same offset
558 * and base.
559 *
560 * <p>As of 1.4.1, offsets for fields are represented as long values,
561 * although the Sun JVM does not use the most significant 32 bits.
562 * However, JVM implementations which store static fields at absolute
563 * addresses can use long offsets and null base pointers to express
564 * the field locations in a form usable by {@link #getInt(Object,long)}.
565 * Therefore, code which will be ported to such JVMs on 64-bit platforms
566 * must preserve all bits of static field offsets.
567 * @see #getInt(Object, long)
568 */
569 public native long objectFieldOffset(Field f);
570
571 /**
572 * Reports the location of a given static field, in conjunction with {@link
573 * #staticFieldBase}.
574 * <p>Do not expect to perform any sort of arithmetic on this offset;
575 * it is just a cookie which is passed to the unsafe heap memory accessors.
576 *
577 * <p>Any given field will always have the same offset, and no two distinct
578 * fields of the same class will ever have the same offset.
579 *
580 * <p>As of 1.4.1, offsets for fields are represented as long values,
581 * although the Sun JVM does not use the most significant 32 bits.
582 * It is hard to imagine a JVM technology which needs more than
583 * a few bits to encode an offset within a non-array object,
584 * However, for consistency with other methods in this class,
585 * this method reports its result as a long value.
586 * @see #getInt(Object, long)
587 */
588 public native long staticFieldOffset(Field f);
589
590 /**
591 * Reports the location of a given static field, in conjunction with {@link
592 * #staticFieldOffset}.
593 * <p>Fetch the base "Object", if any, with which static fields of the
594 * given class can be accessed via methods like {@link #getInt(Object,
595 * long)}. This value may be null. This value may refer to an object
596 * which is a "cookie", not guaranteed to be a real Object, and it should
597 * not be used in any way except as argument to the get and put routines in
598 * this class.
599 */
600 public native Object staticFieldBase(Field f);
601
602 /**
603 * Detects if the given class may need to be initialized. This is often
604 * needed in conjunction with obtaining the static field base of a
605 * class.
606 * @return false only if a call to {@code ensureClassInitialized} would have no effect
607 */
608 public native boolean shouldBeInitialized(Class<?> c);
609
610 /**
611 * Ensures the given class has been initialized. This is often
612 * needed in conjunction with obtaining the static field base of a
613 * class.
614 */
615 public native void ensureClassInitialized(Class<?> c);
616
617 /**
618 * Reports the offset of the first element in the storage allocation of a
619 * given array class. If {@link #arrayIndexScale} returns a non-zero value
620 * for the same class, you may use that scale factor, together with this
621 * base offset, to form new offsets to access elements of arrays of the
622 * given class.
623 *
624 * @see #getInt(Object, long)
625 * @see #putInt(Object, long, int)
626 */
627 public native int arrayBaseOffset(Class<?> arrayClass);
628
629 /** The value of {@code arrayBaseOffset(boolean[].class)} */
630 public static final int ARRAY_BOOLEAN_BASE_OFFSET
631 = theUnsafe.arrayBaseOffset(boolean[].class);
632
633 /** The value of {@code arrayBaseOffset(byte[].class)} */
634 public static final int ARRAY_BYTE_BASE_OFFSET
635 = theUnsafe.arrayBaseOffset(byte[].class);
636
637 /** The value of {@code arrayBaseOffset(short[].class)} */
638 public static final int ARRAY_SHORT_BASE_OFFSET
639 = theUnsafe.arrayBaseOffset(short[].class);
640
641 /** The value of {@code arrayBaseOffset(char[].class)} */
642 public static final int ARRAY_CHAR_BASE_OFFSET
643 = theUnsafe.arrayBaseOffset(char[].class);
644
645 /** The value of {@code arrayBaseOffset(int[].class)} */
646 public static final int ARRAY_INT_BASE_OFFSET
647 = theUnsafe.arrayBaseOffset(int[].class);
648
649 /** The value of {@code arrayBaseOffset(long[].class)} */
650 public static final int ARRAY_LONG_BASE_OFFSET
651 = theUnsafe.arrayBaseOffset(long[].class);
652
653 /** The value of {@code arrayBaseOffset(float[].class)} */
654 public static final int ARRAY_FLOAT_BASE_OFFSET
655 = theUnsafe.arrayBaseOffset(float[].class);
656
657 /** The value of {@code arrayBaseOffset(double[].class)} */
658 public static final int ARRAY_DOUBLE_BASE_OFFSET
659 = theUnsafe.arrayBaseOffset(double[].class);
660
661 /** The value of {@code arrayBaseOffset(Object[].class)} */
662 public static final int ARRAY_OBJECT_BASE_OFFSET
663 = theUnsafe.arrayBaseOffset(Object[].class);
664
665 /**
666 * Reports the scale factor for addressing elements in the storage
667 * allocation of a given array class. However, arrays of "narrow" types
668 * will generally not work properly with accessors like {@link
669 * #getByte(Object, long)}, so the scale factor for such classes is reported
670 * as zero.
671 *
672 * @see #arrayBaseOffset
673 * @see #getInt(Object, long)
674 * @see #putInt(Object, long, int)
675 */
676 public native int arrayIndexScale(Class<?> arrayClass);
677
678 /** The value of {@code arrayIndexScale(boolean[].class)} */
679 public static final int ARRAY_BOOLEAN_INDEX_SCALE
680 = theUnsafe.arrayIndexScale(boolean[].class);
681
682 /** The value of {@code arrayIndexScale(byte[].class)} */
683 public static final int ARRAY_BYTE_INDEX_SCALE
684 = theUnsafe.arrayIndexScale(byte[].class);
685
686 /** The value of {@code arrayIndexScale(short[].class)} */
687 public static final int ARRAY_SHORT_INDEX_SCALE
688 = theUnsafe.arrayIndexScale(short[].class);
689
690 /** The value of {@code arrayIndexScale(char[].class)} */
691 public static final int ARRAY_CHAR_INDEX_SCALE
692 = theUnsafe.arrayIndexScale(char[].class);
693
694 /** The value of {@code arrayIndexScale(int[].class)} */
695 public static final int ARRAY_INT_INDEX_SCALE
696 = theUnsafe.arrayIndexScale(int[].class);
697
698 /** The value of {@code arrayIndexScale(long[].class)} */
699 public static final int ARRAY_LONG_INDEX_SCALE
700 = theUnsafe.arrayIndexScale(long[].class);
701
702 /** The value of {@code arrayIndexScale(float[].class)} */
703 public static final int ARRAY_FLOAT_INDEX_SCALE
704 = theUnsafe.arrayIndexScale(float[].class);
705
706 /** The value of {@code arrayIndexScale(double[].class)} */
707 public static final int ARRAY_DOUBLE_INDEX_SCALE
708 = theUnsafe.arrayIndexScale(double[].class);
709
710 /** The value of {@code arrayIndexScale(Object[].class)} */
711 public static final int ARRAY_OBJECT_INDEX_SCALE
712 = theUnsafe.arrayIndexScale(Object[].class);
713
714 /**
715 * Reports the size in bytes of a native pointer, as stored via {@link
716 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
717 * other primitive types (as stored in native memory blocks) is determined
718 * fully by their information content.
719 */
720 public native int addressSize();
721
722 /** The value of {@code addressSize()} */
723 public static final int ADDRESS_SIZE = theUnsafe.addressSize();
724
725 /**
726 * Reports the size in bytes of a native memory page (whatever that is).
727 * This value will always be a power of two.
728 */
729 public native int pageSize();
730
731
732 /// random trusted operations from JNI:
733
734 /**
735 * Tells the VM to define a class, without security checks. By default, the
736 * class loader and protection domain come from the caller's class.
737 */
738 public native Class<?> defineClass(String name, byte[] b, int off, int len,
739 ClassLoader loader,
740 ProtectionDomain protectionDomain);
741
742 /**
743 * Defines a class but does not make it known to the class loader or system dictionary.
744 * <p>
745 * For each CP entry, the corresponding CP patch must either be null or have
746 * the a format that matches its tag:
747 * <ul>
748 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
749 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
750 * <li>Class: any java.lang.Class object
751 * <li>String: any object (not just a java.lang.String)
752 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
753 * </ul>
754 * @param hostClass context for linkage, access control, protection domain, and class loader
755 * @param data bytes of a class file
756 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
757 */
758 public native Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches);
759
760 /**
761 * Allocates an instance but does not run any constructor.
762 * Initializes the class if it has not yet been.
763 */
764 @HotSpotIntrinsicCandidate
765 public native Object allocateInstance(Class<?> cls)
766 throws InstantiationException;
767
768 /** Throws the exception without telling the verifier. */
769 public native void throwException(Throwable ee);
770
771 /**
772 * Atomically updates Java variable to {@code x} if it is currently
773 * holding {@code expected}.
774 *
775 * <p>This operation has memory semantics of a {@code volatile} read
776 * and write. Corresponds to C11 atomic_compare_exchange_strong.
777 *
778 * @return {@code true} if successful
779 */
780 @HotSpotIntrinsicCandidate
781 public final native boolean compareAndSwapObject(Object o, long offset,
782 Object expected,
783 Object x);
784
785 /**
786 * Atomically updates Java variable to {@code x} if it is currently
787 * holding {@code expected}.
788 *
789 * <p>This operation has memory semantics of a {@code volatile} read
790 * and write. Corresponds to C11 atomic_compare_exchange_strong.
791 *
792 * @return {@code true} if successful
793 */
794 @HotSpotIntrinsicCandidate
795 public final native boolean compareAndSwapInt(Object o, long offset,
796 int expected,
797 int x);
798
799 /**
800 * Atomically updates Java variable to {@code x} if it is currently
801 * holding {@code expected}.
802 *
803 * <p>This operation has memory semantics of a {@code volatile} read
804 * and write. Corresponds to C11 atomic_compare_exchange_strong.
805 *
806 * @return {@code true} if successful
807 */
808 @HotSpotIntrinsicCandidate
809 public final native boolean compareAndSwapLong(Object o, long offset,
810 long expected,
811 long x);
812
813 /**
814 * Fetches a reference value from a given Java variable, with volatile
815 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
816 */
817 @HotSpotIntrinsicCandidate
818 public native Object getObjectVolatile(Object o, long offset);
819
820 /**
821 * Stores a reference value into a given Java variable, with
822 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
823 */
824 @HotSpotIntrinsicCandidate
825 public native void putObjectVolatile(Object o, long offset, Object x);
826
827 /** Volatile version of {@link #getInt(Object, long)} */
828 @HotSpotIntrinsicCandidate
829 public native int getIntVolatile(Object o, long offset);
830
831 /** Volatile version of {@link #putInt(Object, long, int)} */
832 @HotSpotIntrinsicCandidate
833 public native void putIntVolatile(Object o, long offset, int x);
834
835 /** Volatile version of {@link #getBoolean(Object, long)} */
836 @HotSpotIntrinsicCandidate
837 public native boolean getBooleanVolatile(Object o, long offset);
838
839 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
840 @HotSpotIntrinsicCandidate
841 public native void putBooleanVolatile(Object o, long offset, boolean x);
842
843 /** Volatile version of {@link #getByte(Object, long)} */
844 @HotSpotIntrinsicCandidate
845 public native byte getByteVolatile(Object o, long offset);
846
847 /** Volatile version of {@link #putByte(Object, long, byte)} */
848 @HotSpotIntrinsicCandidate
849 public native void putByteVolatile(Object o, long offset, byte x);
850
851 /** Volatile version of {@link #getShort(Object, long)} */
852 @HotSpotIntrinsicCandidate
853 public native short getShortVolatile(Object o, long offset);
854
855 /** Volatile version of {@link #putShort(Object, long, short)} */
856 @HotSpotIntrinsicCandidate
857 public native void putShortVolatile(Object o, long offset, short x);
858
859 /** Volatile version of {@link #getChar(Object, long)} */
860 @HotSpotIntrinsicCandidate
861 public native char getCharVolatile(Object o, long offset);
862
863 /** Volatile version of {@link #putChar(Object, long, char)} */
864 @HotSpotIntrinsicCandidate
865 public native void putCharVolatile(Object o, long offset, char x);
866
867 /** Volatile version of {@link #getLong(Object, long)} */
868 @HotSpotIntrinsicCandidate
869 public native long getLongVolatile(Object o, long offset);
870
871 /** Volatile version of {@link #putLong(Object, long, long)} */
872 @HotSpotIntrinsicCandidate
873 public native void putLongVolatile(Object o, long offset, long x);
874
875 /** Volatile version of {@link #getFloat(Object, long)} */
876 @HotSpotIntrinsicCandidate
877 public native float getFloatVolatile(Object o, long offset);
878
879 /** Volatile version of {@link #putFloat(Object, long, float)} */
880 @HotSpotIntrinsicCandidate
881 public native void putFloatVolatile(Object o, long offset, float x);
882
883 /** Volatile version of {@link #getDouble(Object, long)} */
884 @HotSpotIntrinsicCandidate
885 public native double getDoubleVolatile(Object o, long offset);
886
887 /** Volatile version of {@link #putDouble(Object, long, double)} */
888 @HotSpotIntrinsicCandidate
889 public native void putDoubleVolatile(Object o, long offset, double x);
890
891 /**
892 * Version of {@link #putObjectVolatile(Object, long, Object)}
893 * that does not guarantee immediate visibility of the store to
894 * other threads. This method is generally only useful if the
895 * underlying field is a Java volatile (or if an array cell, one
896 * that is otherwise only accessed using volatile accesses).
897 *
898 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
899 */
900 @HotSpotIntrinsicCandidate
901 public native void putOrderedObject(Object o, long offset, Object x);
902
903 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
904 @HotSpotIntrinsicCandidate
905 public native void putOrderedInt(Object o, long offset, int x);
906
907 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
908 @HotSpotIntrinsicCandidate
909 public native void putOrderedLong(Object o, long offset, long x);
910
911 /**
912 * Unblocks the given thread blocked on {@code park}, or, if it is
913 * not blocked, causes the subsequent call to {@code park} not to
914 * block. Note: this operation is "unsafe" solely because the
915 * caller must somehow ensure that the thread has not been
916 * destroyed. Nothing special is usually required to ensure this
917 * when called from Java (in which there will ordinarily be a live
918 * reference to the thread) but this is not nearly-automatically
919 * so when calling from native code.
920 *
921 * @param thread the thread to unpark.
922 */
923 @HotSpotIntrinsicCandidate
924 public native void unpark(Object thread);
925
926 /**
927 * Blocks current thread, returning when a balancing
928 * {@code unpark} occurs, or a balancing {@code unpark} has
929 * already occurred, or the thread is interrupted, or, if not
930 * absolute and time is not zero, the given time nanoseconds have
931 * elapsed, or if absolute, the given deadline in milliseconds
932 * since Epoch has passed, or spuriously (i.e., returning for no
933 * "reason"). Note: This operation is in the Unsafe class only
934 * because {@code unpark} is, so it would be strange to place it
935 * elsewhere.
936 */
937 @HotSpotIntrinsicCandidate
938 public native void park(boolean isAbsolute, long time);
939
940 /**
941 * Gets the load average in the system run queue assigned
942 * to the available processors averaged over various periods of time.
943 * This method retrieves the given {@code nelem} samples and
944 * assigns to the elements of the given {@code loadavg} array.
945 * The system imposes a maximum of 3 samples, representing
946 * averages over the last 1, 5, and 15 minutes, respectively.
947 *
948 * @param loadavg an array of double of size nelems
949 * @param nelems the number of samples to be retrieved and
950 * must be 1 to 3.
951 *
952 * @return the number of samples actually retrieved; or -1
953 * if the load average is unobtainable.
954 */
955 public native int getLoadAverage(double[] loadavg, int nelems);
956
957 // The following contain CAS-based Java implementations used on
958 // platforms not supporting native instructions
959
960 /**
961 * Atomically adds the given value to the current value of a field
962 * or array element within the given object {@code o}
963 * at the given {@code offset}.
964 *
965 * @param o object/array to update the field/element in
966 * @param offset field/element offset
967 * @param delta the value to add
968 * @return the previous value
969 * @since 1.8
970 */
971 @HotSpotIntrinsicCandidate
972 public final int getAndAddInt(Object o, long offset, int delta) {
973 int v;
974 do {
975 v = getIntVolatile(o, offset);
976 } while (!compareAndSwapInt(o, offset, v, v + delta));
977 return v;
978 }
979
980 /**
981 * Atomically adds the given value to the current value of a field
982 * or array element within the given object {@code o}
983 * at the given {@code offset}.
984 *
985 * @param o object/array to update the field/element in
986 * @param offset field/element offset
987 * @param delta the value to add
988 * @return the previous value
989 * @since 1.8
990 */
991 @HotSpotIntrinsicCandidate
992 public final long getAndAddLong(Object o, long offset, long delta) {
993 long v;
994 do {
995 v = getLongVolatile(o, offset);
996 } while (!compareAndSwapLong(o, offset, v, v + delta));
997 return v;
998 }
999
1000 /**
1001 * Atomically exchanges the given value with the current value of
1002 * a field or array element within the given object {@code o}
1003 * at the given {@code offset}.
1004 *
1005 * @param o object/array to update the field/element in
1006 * @param offset field/element offset
1007 * @param newValue new value
1008 * @return the previous value
1009 * @since 1.8
1010 */
1011 @HotSpotIntrinsicCandidate
1012 public final int getAndSetInt(Object o, long offset, int newValue) {
1013 int v;
1014 do {
1015 v = getIntVolatile(o, offset);
1016 } while (!compareAndSwapInt(o, offset, v, newValue));
1017 return v;
1018 }
1019
1020 /**
1021 * Atomically exchanges the given value with the current value of
1022 * a field or array element within the given object {@code o}
1023 * at the given {@code offset}.
1024 *
1025 * @param o object/array to update the field/element in
1026 * @param offset field/element offset
1027 * @param newValue new value
1028 * @return the previous value
1029 * @since 1.8
1030 */
1031 @HotSpotIntrinsicCandidate
1032 public final long getAndSetLong(Object o, long offset, long newValue) {
1033 long v;
1034 do {
1035 v = getLongVolatile(o, offset);
1036 } while (!compareAndSwapLong(o, offset, v, newValue));
1037 return v;
1038 }
1039
1040 /**
1041 * Atomically exchanges the given reference value with the current
1042 * reference value of a field or array element within the given
1043 * object {@code o} at the given {@code offset}.
1044 *
1045 * @param o object/array to update the field/element in
1046 * @param offset field/element offset
1047 * @param newValue new value
1048 * @return the previous value
1049 * @since 1.8
1050 */
1051 @HotSpotIntrinsicCandidate
1052 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1053 Object v;
1054 do {
1055 v = getObjectVolatile(o, offset);
1056 } while (!compareAndSwapObject(o, offset, v, newValue));
1057 return v;
1058 }
1059
1060
1061 /**
1062 * Ensures that loads before the fence will not be reordered with loads and
1063 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1064 *
1065 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1066 * (an "acquire fence").
1067 *
1068 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1069 * is almost always desired, and most current hardware instructions that
1070 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1071 * @since 1.8
1072 */
1073 @HotSpotIntrinsicCandidate
1074 public native void loadFence();
1075
1076 /**
1077 * Ensures that loads and stores before the fence will not be reordered with
1078 * stores after the fence; a "StoreStore plus LoadStore barrier".
1079 *
1080 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1081 * (a "release fence").
1082 *
1083 * A pure StoreStore fence is not provided, since the addition of LoadStore
1084 * is almost always desired, and most current hardware instructions that
1085 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1086 * @since 1.8
1087 */
1088 @HotSpotIntrinsicCandidate
1089 public native void storeFence();
1090
1091 /**
1092 * Ensures that loads and stores before the fence will not be reordered
1093 * with loads and stores after the fence. Implies the effects of both
1094 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1095 * barrier.
1096 *
1097 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1098 * @since 1.8
1099 */
1100 @HotSpotIntrinsicCandidate
1101 public native void fullFence();
1102
1103 /**
1104 * Throws IllegalAccessError; for use by the VM for access control
1105 * error support.
1106 * @since 1.8
1107 */
1108 private static void throwIllegalAccessError() {
1109 throw new IllegalAccessError();
1110 }
1111
1112 /**
1113 * @return Returns true if the native byte ordering of this
1114 * platform is big-endian, false if it is little-endian.
1115 */
1116 public final boolean isBigEndian() { return BE; }
1117
1118 /**
1119 * @return Returns true if this platform is capable of performing
1120 * accesses at addresses which are not aligned for the type of the
1121 * primitive type being accessed, false otherwise.
1122 */
1123 public final boolean unalignedAccess() { return unalignedAccess; }
1124
1125 /**
1126 * Fetches a value at some byte offset into a given Java object.
1127 * More specifically, fetches a value within the given object
1128 * <code>o</code> at the given offset, or (if <code>o</code> is
1129 * null) from the memory address whose numerical value is the
1130 * given offset. <p>
1131 *
1132 * The specification of this method is the same as {@link
1133 * #getLong(Object, long)} except that the offset does not need to
1134 * have been obtained from {@link #objectFieldOffset} on the
1135 * {@link java.lang.reflect.Field} of some Java field. The value
1136 * in memory is raw data, and need not correspond to any Java
1137 * variable. Unless <code>o</code> is null, the value accessed
1138 * must be entirely within the allocated object. The endianness
1139 * of the value in memory is the endianness of the native platform.
1140 *
1141 * <p> The read will be atomic with respect to the largest power
1142 * of two that divides the GCD of the offset and the storage size.
1143 * For example, getLongUnaligned will make atomic reads of 2-, 4-,
1144 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1145 * respectively. There are no other guarantees of atomicity.
1146 * <p>
1147 * 8-byte atomicity is only guaranteed on platforms on which
1148 * support atomic accesses to longs.
1149 *
1150 * @param o Java heap object in which the value resides, if any, else
1151 * null
1152 * @param offset The offset in bytes from the start of the object
1153 * @return the value fetched from the indicated object
1154 * @throws RuntimeException No defined exceptions are thrown, not even
1155 * {@link NullPointerException}
1156 * @since 9
1157 */
1158 @HotSpotIntrinsicCandidate
1159 public final long getLongUnaligned(Object o, long offset) {
1160 if ((offset & 7) == 0) {
1161 return getLong(o, offset);
1162 } else if ((offset & 3) == 0) {
1163 return makeLong(getInt(o, offset),
1164 getInt(o, offset + 4));
1165 } else if ((offset & 1) == 0) {
1166 return makeLong(getShort(o, offset),
1167 getShort(o, offset + 2),
1168 getShort(o, offset + 4),
1169 getShort(o, offset + 6));
1170 } else {
1171 return makeLong(getByte(o, offset),
1172 getByte(o, offset + 1),
1173 getByte(o, offset + 2),
1174 getByte(o, offset + 3),
1175 getByte(o, offset + 4),
1176 getByte(o, offset + 5),
1177 getByte(o, offset + 6),
1178 getByte(o, offset + 7));
1179 }
1180 }
1181 /**
1182 * As {@link #getLongUnaligned(Object, long)} but with an
1183 * additional argument which specifies the endianness of the value
1184 * as stored in memory.
1185 *
1186 * @param o Java heap object in which the variable resides
1187 * @param offset The offset in bytes from the start of the object
1188 * @param bigEndian The endianness of the value
1189 * @return the value fetched from the indicated object
1190 * @since 9
1191 */
1192 public final long getLongUnaligned(Object o, long offset, boolean bigEndian) {
1193 return convEndian(bigEndian, getLongUnaligned(o, offset));
1194 }
1195
1196 /** @see #getLongUnaligned(Object, long) */
1197 @HotSpotIntrinsicCandidate
1198 public final int getIntUnaligned(Object o, long offset) {
1199 if ((offset & 3) == 0) {
1200 return getInt(o, offset);
1201 } else if ((offset & 1) == 0) {
1202 return makeInt(getShort(o, offset),
1203 getShort(o, offset + 2));
1204 } else {
1205 return makeInt(getByte(o, offset),
1206 getByte(o, offset + 1),
1207 getByte(o, offset + 2),
1208 getByte(o, offset + 3));
1209 }
1210 }
1211 /** @see #getLongUnaligned(Object, long, boolean) */
1212 public final int getIntUnaligned(Object o, long offset, boolean bigEndian) {
1213 return convEndian(bigEndian, getIntUnaligned(o, offset));
1214 }
1215
1216 /** @see #getLongUnaligned(Object, long) */
1217 @HotSpotIntrinsicCandidate
1218 public final short getShortUnaligned(Object o, long offset) {
1219 if ((offset & 1) == 0) {
1220 return getShort(o, offset);
1221 } else {
1222 return makeShort(getByte(o, offset),
1223 getByte(o, offset + 1));
1224 }
1225 }
1226 /** @see #getLongUnaligned(Object, long, boolean) */
1227 public final short getShortUnaligned(Object o, long offset, boolean bigEndian) {
1228 return convEndian(bigEndian, getShortUnaligned(o, offset));
1229 }
1230
1231 /** @see #getLongUnaligned(Object, long) */
1232 @HotSpotIntrinsicCandidate
1233 public final char getCharUnaligned(Object o, long offset) {
1234 if ((offset & 1) == 0) {
1235 return getChar(o, offset);
1236 } else {
1237 return (char)makeShort(getByte(o, offset),
1238 getByte(o, offset + 1));
1239 }
1240 }
1241
1242 /** @see #getLongUnaligned(Object, long, boolean) */
1243 public final char getCharUnaligned(Object o, long offset, boolean bigEndian) {
1244 return convEndian(bigEndian, getCharUnaligned(o, offset));
1245 }
1246
1247 /**
1248 * Stores a value at some byte offset into a given Java object.
1249 * <p>
1250 * The specification of this method is the same as {@link
1251 * #getLong(Object, long)} except that the offset does not need to
1252 * have been obtained from {@link #objectFieldOffset} on the
1253 * {@link java.lang.reflect.Field} of some Java field. The value
1254 * in memory is raw data, and need not correspond to any Java
1255 * variable. The endianness of the value in memory is the
1256 * endianness of the native platform.
1257 * <p>
1258 * The write will be atomic with respect to the largest power of
1259 * two that divides the GCD of the offset and the storage size.
1260 * For example, putLongUnaligned will make atomic writes of 2-, 4-,
1261 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1262 * respectively. There are no other guarantees of atomicity.
1263 * <p>
1264 * 8-byte atomicity is only guaranteed on platforms on which
1265 * support atomic accesses to longs.
1266 *
1267 * @param o Java heap object in which the value resides, if any, else
1268 * null
1269 * @param offset The offset in bytes from the start of the object
1270 * @param x the value to store
1271 * @throws RuntimeException No defined exceptions are thrown, not even
1272 * {@link NullPointerException}
1273 * @since 9
1274 */
1275 @HotSpotIntrinsicCandidate
1276 public final void putLongUnaligned(Object o, long offset, long x) {
1277 if ((offset & 7) == 0) {
1278 putLong(o, offset, x);
1279 } else if ((offset & 3) == 0) {
1280 putLongParts(o, offset,
1281 (int)(x >> 0),
1282 (int)(x >>> 32));
1283 } else if ((offset & 1) == 0) {
1284 putLongParts(o, offset,
1285 (short)(x >>> 0),
1286 (short)(x >>> 16),
1287 (short)(x >>> 32),
1288 (short)(x >>> 48));
1289 } else {
1290 putLongParts(o, offset,
1291 (byte)(x >>> 0),
1292 (byte)(x >>> 8),
1293 (byte)(x >>> 16),
1294 (byte)(x >>> 24),
1295 (byte)(x >>> 32),
1296 (byte)(x >>> 40),
1297 (byte)(x >>> 48),
1298 (byte)(x >>> 56));
1299 }
1300 }
1301
1302 /**
1303 * As {@link #putLongUnaligned(Object, long, long)} but with an additional
1304 * argument which specifies the endianness of the value as stored in memory.
1305 * @param o Java heap object in which the value resides
1306 * @param offset The offset in bytes from the start of the object
1307 * @param x the value to store
1308 * @param bigEndian The endianness of the value
1309 * @throws RuntimeException No defined exceptions are thrown, not even
1310 * {@link NullPointerException}
1311 * @since 9
1312 */
1313 public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) {
1314 putLongUnaligned(o, offset, convEndian(bigEndian, x));
1315 }
1316
1317 /** @see #putLongUnaligned(Object, long, long) */
1318 @HotSpotIntrinsicCandidate
1319 public final void putIntUnaligned(Object o, long offset, int x) {
1320 if ((offset & 3) == 0) {
1321 putInt(o, offset, x);
1322 } else if ((offset & 1) == 0) {
1323 putIntParts(o, offset,
1324 (short)(x >> 0),
1325 (short)(x >>> 16));
1326 } else {
1327 putIntParts(o, offset,
1328 (byte)(x >>> 0),
1329 (byte)(x >>> 8),
1330 (byte)(x >>> 16),
1331 (byte)(x >>> 24));
1332 }
1333 }
1334 /** @see #putLongUnaligned(Object, long, long, boolean) */
1335 public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) {
1336 putIntUnaligned(o, offset, convEndian(bigEndian, x));
1337 }
1338
1339 /** @see #putLongUnaligned(Object, long, long) */
1340 @HotSpotIntrinsicCandidate
1341 public final void putShortUnaligned(Object o, long offset, short x) {
1342 if ((offset & 1) == 0) {
1343 putShort(o, offset, x);
1344 } else {
1345 putShortParts(o, offset,
1346 (byte)(x >>> 0),
1347 (byte)(x >>> 8));
1348 }
1349 }
1350 /** @see #putLongUnaligned(Object, long, long, boolean) */
1351 public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) {
1352 putShortUnaligned(o, offset, convEndian(bigEndian, x));
1353 }
1354
1355 /** @see #putLongUnaligned(Object, long, long) */
1356 @HotSpotIntrinsicCandidate
1357 public final void putCharUnaligned(Object o, long offset, char x) {
1358 putShortUnaligned(o, offset, (short)x);
1359 }
1360 /** @see #putLongUnaligned(Object, long, long, boolean) */
1361 public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) {
1362 putCharUnaligned(o, offset, convEndian(bigEndian, x));
1363 }
1364
1365 // JVM interface methods
1366 private native boolean unalignedAccess0();
1367 private native boolean isBigEndian0();
1368
1369 // BE is true iff the native endianness of this platform is big.
1370 private static final boolean BE = theUnsafe.isBigEndian0();
1371
1372 // unalignedAccess is true iff this platform can perform unaligned accesses.
1373 private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
1374
1375 private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
1376
1377 // These methods construct integers from bytes. The byte ordering
1378 // is the native endianness of this platform.
1379 private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
1380 return ((toUnsignedLong(i0) << pickPos(56, 0))
1381 | (toUnsignedLong(i1) << pickPos(56, 8))
1382 | (toUnsignedLong(i2) << pickPos(56, 16))
1383 | (toUnsignedLong(i3) << pickPos(56, 24))
1384 | (toUnsignedLong(i4) << pickPos(56, 32))
1385 | (toUnsignedLong(i5) << pickPos(56, 40))
1386 | (toUnsignedLong(i6) << pickPos(56, 48))
1387 | (toUnsignedLong(i7) << pickPos(56, 56)));
1388 }
1389 private static long makeLong(short i0, short i1, short i2, short i3) {
1390 return ((toUnsignedLong(i0) << pickPos(48, 0))
1391 | (toUnsignedLong(i1) << pickPos(48, 16))
1392 | (toUnsignedLong(i2) << pickPos(48, 32))
1393 | (toUnsignedLong(i3) << pickPos(48, 48)));
1394 }
1395 private static long makeLong(int i0, int i1) {
1396 return (toUnsignedLong(i0) << pickPos(32, 0))
1397 | (toUnsignedLong(i1) << pickPos(32, 32));
1398 }
1399 private static int makeInt(short i0, short i1) {
1400 return (toUnsignedInt(i0) << pickPos(16, 0))
1401 | (toUnsignedInt(i1) << pickPos(16, 16));
1402 }
1403 private static int makeInt(byte i0, byte i1, byte i2, byte i3) {
1404 return ((toUnsignedInt(i0) << pickPos(24, 0))
1405 | (toUnsignedInt(i1) << pickPos(24, 8))
1406 | (toUnsignedInt(i2) << pickPos(24, 16))
1407 | (toUnsignedInt(i3) << pickPos(24, 24)));
1408 }
1409 private static short makeShort(byte i0, byte i1) {
1410 return (short)((toUnsignedInt(i0) << pickPos(8, 0))
1411 | (toUnsignedInt(i1) << pickPos(8, 8)));
1412 }
1413
1414 private static byte pick(byte le, byte be) { return BE ? be : le; }
1415 private static short pick(short le, short be) { return BE ? be : le; }
1416 private static int pick(int le, int be) { return BE ? be : le; }
1417
1418 // These methods write integers to memory from smaller parts
1419 // provided by their caller. The ordering in which these parts
1420 // are written is the native endianness of this platform.
1421 private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
1422 putByte(o, offset + 0, pick(i0, i7));
1423 putByte(o, offset + 1, pick(i1, i6));
1424 putByte(o, offset + 2, pick(i2, i5));
1425 putByte(o, offset + 3, pick(i3, i4));
1426 putByte(o, offset + 4, pick(i4, i3));
1427 putByte(o, offset + 5, pick(i5, i2));
1428 putByte(o, offset + 6, pick(i6, i1));
1429 putByte(o, offset + 7, pick(i7, i0));
1430 }
1431 private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) {
1432 putShort(o, offset + 0, pick(i0, i3));
1433 putShort(o, offset + 2, pick(i1, i2));
1434 putShort(o, offset + 4, pick(i2, i1));
1435 putShort(o, offset + 6, pick(i3, i0));
1436 }
1437 private void putLongParts(Object o, long offset, int i0, int i1) {
1438 putInt(o, offset + 0, pick(i0, i1));
1439 putInt(o, offset + 4, pick(i1, i0));
1440 }
1441 private void putIntParts(Object o, long offset, short i0, short i1) {
1442 putShort(o, offset + 0, pick(i0, i1));
1443 putShort(o, offset + 2, pick(i1, i0));
1444 }
1445 private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) {
1446 putByte(o, offset + 0, pick(i0, i3));
1447 putByte(o, offset + 1, pick(i1, i2));
1448 putByte(o, offset + 2, pick(i2, i1));
1449 putByte(o, offset + 3, pick(i3, i0));
1450 }
1451 private void putShortParts(Object o, long offset, byte i0, byte i1) {
1452 putByte(o, offset + 0, pick(i0, i1));
1453 putByte(o, offset + 1, pick(i1, i0));
1454 }
1455
1456 // Zero-extend an integer
1457 private static int toUnsignedInt(byte n) { return n & 0xff; }
1458 private static int toUnsignedInt(short n) { return n & 0xffff; }
1459 private static long toUnsignedLong(byte n) { return n & 0xffl; }
1460 private static long toUnsignedLong(short n) { return n & 0xffffl; }
1461 private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
1462
1463 // Maybe byte-reverse an integer
1464 private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
1465 private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
1466 private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
1467 private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
1468 }