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