Sun, 13 Apr 2008 17:43:42 -0400
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold
1 /*
2 * Copyright 1997-2007 Sun Microsystems, Inc. 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
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23 */
25 // Implementation of all inlined member functions defined in oop.hpp
26 // We need a separate file to avoid circular references
28 inline void oopDesc::release_set_mark(markOop m) {
29 OrderAccess::release_store_ptr(&_mark, m);
30 }
32 inline markOop oopDesc::cas_set_mark(markOop new_mark, markOop old_mark) {
33 return (markOop) Atomic::cmpxchg_ptr(new_mark, &_mark, old_mark);
34 }
36 inline klassOop oopDesc::klass() const {
37 if (UseCompressedOops) {
38 return (klassOop)decode_heap_oop_not_null(_metadata._compressed_klass);
39 // can be NULL in CMS, but isn't supported on CMS yet.
40 } else {
41 return _metadata._klass;
42 }
43 }
45 inline int oopDesc::klass_gap_offset_in_bytes() {
46 assert(UseCompressedOops, "only applicable to compressed headers");
47 return oopDesc::klass_offset_in_bytes() + sizeof(narrowOop);
48 }
50 inline oop* oopDesc::klass_addr() {
51 // Only used internally and with CMS and will not work with
52 // UseCompressedOops
53 assert(!UseCompressedOops, "only supported with uncompressed oops");
54 return (oop*) &_metadata._klass;
55 }
57 inline narrowOop* oopDesc::compressed_klass_addr() {
58 assert(UseCompressedOops, "only called by compressed oops");
59 return (narrowOop*) &_metadata._compressed_klass;
60 }
62 inline void oopDesc::set_klass(klassOop k) {
63 // since klasses are promoted no store check is needed
64 assert(Universe::is_bootstrapping() || k != NULL, "must be a real klassOop");
65 assert(Universe::is_bootstrapping() || k->is_klass(), "not a klassOop");
66 if (UseCompressedOops) {
67 // zero the gap when the klass is set, by zeroing the pointer sized
68 // part of the union.
69 _metadata._klass = NULL;
70 oop_store_without_check(compressed_klass_addr(), (oop)k);
71 } else {
72 oop_store_without_check(klass_addr(), (oop) k);
73 }
74 }
76 inline void oopDesc::set_klass_to_list_ptr(oop k) {
77 // This is only to be used during GC, for from-space objects, so no
78 // barrier is needed.
79 if (UseCompressedOops) {
80 _metadata._compressed_klass = encode_heap_oop_not_null(k);
81 } else {
82 _metadata._klass = (klassOop)k;
83 }
84 }
86 inline void oopDesc::init_mark() { set_mark(markOopDesc::prototype_for_object(this)); }
87 inline Klass* oopDesc::blueprint() const { return klass()->klass_part(); }
89 inline bool oopDesc::is_a(klassOop k) const { return blueprint()->is_subtype_of(k); }
91 inline bool oopDesc::is_instance() const { return blueprint()->oop_is_instance(); }
92 inline bool oopDesc::is_instanceRef() const { return blueprint()->oop_is_instanceRef(); }
93 inline bool oopDesc::is_array() const { return blueprint()->oop_is_array(); }
94 inline bool oopDesc::is_objArray() const { return blueprint()->oop_is_objArray(); }
95 inline bool oopDesc::is_typeArray() const { return blueprint()->oop_is_typeArray(); }
96 inline bool oopDesc::is_javaArray() const { return blueprint()->oop_is_javaArray(); }
97 inline bool oopDesc::is_symbol() const { return blueprint()->oop_is_symbol(); }
98 inline bool oopDesc::is_klass() const { return blueprint()->oop_is_klass(); }
99 inline bool oopDesc::is_thread() const { return blueprint()->oop_is_thread(); }
100 inline bool oopDesc::is_method() const { return blueprint()->oop_is_method(); }
101 inline bool oopDesc::is_constMethod() const { return blueprint()->oop_is_constMethod(); }
102 inline bool oopDesc::is_methodData() const { return blueprint()->oop_is_methodData(); }
103 inline bool oopDesc::is_constantPool() const { return blueprint()->oop_is_constantPool(); }
104 inline bool oopDesc::is_constantPoolCache() const { return blueprint()->oop_is_constantPoolCache(); }
105 inline bool oopDesc::is_compiledICHolder() const { return blueprint()->oop_is_compiledICHolder(); }
107 inline void* oopDesc::field_base(int offset) const { return (void*)&((char*)this)[offset]; }
109 template <class T> inline T* oopDesc::obj_field_addr(int offset) const { return (T*)field_base(offset); }
110 inline jbyte* oopDesc::byte_field_addr(int offset) const { return (jbyte*) field_base(offset); }
111 inline jchar* oopDesc::char_field_addr(int offset) const { return (jchar*) field_base(offset); }
112 inline jboolean* oopDesc::bool_field_addr(int offset) const { return (jboolean*)field_base(offset); }
113 inline jint* oopDesc::int_field_addr(int offset) const { return (jint*) field_base(offset); }
114 inline jshort* oopDesc::short_field_addr(int offset) const { return (jshort*) field_base(offset); }
115 inline jlong* oopDesc::long_field_addr(int offset) const { return (jlong*) field_base(offset); }
116 inline jfloat* oopDesc::float_field_addr(int offset) const { return (jfloat*) field_base(offset); }
117 inline jdouble* oopDesc::double_field_addr(int offset) const { return (jdouble*) field_base(offset); }
118 inline address* oopDesc::address_field_addr(int offset) const { return (address*) field_base(offset); }
121 // Functions for getting and setting oops within instance objects.
122 // If the oops are compressed, the type passed to these overloaded functions
123 // is narrowOop. All functions are overloaded so they can be called by
124 // template functions without conditionals (the compiler instantiates via
125 // the right type and inlines the appopriate code).
127 inline bool oopDesc::is_null(oop obj) { return obj == NULL; }
128 inline bool oopDesc::is_null(narrowOop obj) { return obj == 0; }
130 // Algorithm for encoding and decoding oops from 64 bit pointers to 32 bit
131 // offset from the heap base. Saving the check for null can save instructions
132 // in inner GC loops so these are separated.
134 inline narrowOop oopDesc::encode_heap_oop_not_null(oop v) {
135 assert(!is_null(v), "oop value can never be zero");
136 address heap_base = Universe::heap_base();
137 uint64_t result = (uint64_t)(pointer_delta((void*)v, (void*)heap_base, 1) >> LogMinObjAlignmentInBytes);
138 assert((result & 0xffffffff00000000L) == 0, "narrow oop overflow");
139 return (narrowOop)result;
140 }
142 inline narrowOop oopDesc::encode_heap_oop(oop v) {
143 return (is_null(v)) ? (narrowOop)0 : encode_heap_oop_not_null(v);
144 }
146 inline oop oopDesc::decode_heap_oop_not_null(narrowOop v) {
147 assert(!is_null(v), "narrow oop value can never be zero");
148 address heap_base = Universe::heap_base();
149 return (oop)(void*)((uintptr_t)heap_base + ((uintptr_t)v << LogMinObjAlignmentInBytes));
150 }
152 inline oop oopDesc::decode_heap_oop(narrowOop v) {
153 return is_null(v) ? (oop)NULL : decode_heap_oop_not_null(v);
154 }
156 inline oop oopDesc::decode_heap_oop_not_null(oop v) { return v; }
157 inline oop oopDesc::decode_heap_oop(oop v) { return v; }
159 // Load an oop out of the Java heap as is without decoding.
160 // Called by GC to check for null before decoding.
161 inline oop oopDesc::load_heap_oop(oop* p) { return *p; }
162 inline narrowOop oopDesc::load_heap_oop(narrowOop* p) { return *p; }
164 // Load and decode an oop out of the Java heap into a wide oop.
165 inline oop oopDesc::load_decode_heap_oop_not_null(oop* p) { return *p; }
166 inline oop oopDesc::load_decode_heap_oop_not_null(narrowOop* p) {
167 return decode_heap_oop_not_null(*p);
168 }
170 // Load and decode an oop out of the heap accepting null
171 inline oop oopDesc::load_decode_heap_oop(oop* p) { return *p; }
172 inline oop oopDesc::load_decode_heap_oop(narrowOop* p) {
173 return decode_heap_oop(*p);
174 }
176 // Store already encoded heap oop into the heap.
177 inline void oopDesc::store_heap_oop(oop* p, oop v) { *p = v; }
178 inline void oopDesc::store_heap_oop(narrowOop* p, narrowOop v) { *p = v; }
180 // Encode and store a heap oop.
181 inline void oopDesc::encode_store_heap_oop_not_null(narrowOop* p, oop v) {
182 *p = encode_heap_oop_not_null(v);
183 }
184 inline void oopDesc::encode_store_heap_oop_not_null(oop* p, oop v) { *p = v; }
186 // Encode and store a heap oop allowing for null.
187 inline void oopDesc::encode_store_heap_oop(narrowOop* p, oop v) {
188 *p = encode_heap_oop(v);
189 }
190 inline void oopDesc::encode_store_heap_oop(oop* p, oop v) { *p = v; }
192 // Store heap oop as is for volatile fields.
193 inline void oopDesc::release_store_heap_oop(volatile oop* p, oop v) {
194 OrderAccess::release_store_ptr(p, v);
195 }
196 inline void oopDesc::release_store_heap_oop(volatile narrowOop* p,
197 narrowOop v) {
198 OrderAccess::release_store(p, v);
199 }
201 inline void oopDesc::release_encode_store_heap_oop_not_null(
202 volatile narrowOop* p, oop v) {
203 // heap oop is not pointer sized.
204 OrderAccess::release_store(p, encode_heap_oop_not_null(v));
205 }
207 inline void oopDesc::release_encode_store_heap_oop_not_null(
208 volatile oop* p, oop v) {
209 OrderAccess::release_store_ptr(p, v);
210 }
212 inline void oopDesc::release_encode_store_heap_oop(volatile oop* p,
213 oop v) {
214 OrderAccess::release_store_ptr(p, v);
215 }
216 inline void oopDesc::release_encode_store_heap_oop(
217 volatile narrowOop* p, oop v) {
218 OrderAccess::release_store(p, encode_heap_oop(v));
219 }
222 // These functions are only used to exchange oop fields in instances,
223 // not headers.
224 inline oop oopDesc::atomic_exchange_oop(oop exchange_value, volatile HeapWord *dest) {
225 if (UseCompressedOops) {
226 // encode exchange value from oop to T
227 narrowOop val = encode_heap_oop(exchange_value);
228 narrowOop old = (narrowOop)Atomic::xchg(val, (narrowOop*)dest);
229 // decode old from T to oop
230 return decode_heap_oop(old);
231 } else {
232 return (oop)Atomic::xchg_ptr(exchange_value, (oop*)dest);
233 }
234 }
236 inline oop oopDesc::atomic_compare_exchange_oop(oop exchange_value,
237 volatile HeapWord *dest,
238 oop compare_value) {
239 if (UseCompressedOops) {
240 // encode exchange and compare value from oop to T
241 narrowOop val = encode_heap_oop(exchange_value);
242 narrowOop cmp = encode_heap_oop(compare_value);
244 narrowOop old = (narrowOop) Atomic::cmpxchg(val, (narrowOop*)dest, cmp);
245 // decode old from T to oop
246 return decode_heap_oop(old);
247 } else {
248 return (oop)Atomic::cmpxchg_ptr(exchange_value, (oop*)dest, compare_value);
249 }
250 }
252 // In order to put or get a field out of an instance, must first check
253 // if the field has been compressed and uncompress it.
254 inline oop oopDesc::obj_field(int offset) const {
255 return UseCompressedOops ?
256 load_decode_heap_oop(obj_field_addr<narrowOop>(offset)) :
257 load_decode_heap_oop(obj_field_addr<oop>(offset));
258 }
259 inline void oopDesc::obj_field_put(int offset, oop value) {
260 UseCompressedOops ? oop_store(obj_field_addr<narrowOop>(offset), value) :
261 oop_store(obj_field_addr<oop>(offset), value);
262 }
263 inline void oopDesc::obj_field_raw_put(int offset, oop value) {
264 UseCompressedOops ?
265 encode_store_heap_oop(obj_field_addr<narrowOop>(offset), value) :
266 encode_store_heap_oop(obj_field_addr<oop>(offset), value);
267 }
269 inline jbyte oopDesc::byte_field(int offset) const { return (jbyte) *byte_field_addr(offset); }
270 inline void oopDesc::byte_field_put(int offset, jbyte contents) { *byte_field_addr(offset) = (jint) contents; }
272 inline jboolean oopDesc::bool_field(int offset) const { return (jboolean) *bool_field_addr(offset); }
273 inline void oopDesc::bool_field_put(int offset, jboolean contents) { *bool_field_addr(offset) = (jint) contents; }
275 inline jchar oopDesc::char_field(int offset) const { return (jchar) *char_field_addr(offset); }
276 inline void oopDesc::char_field_put(int offset, jchar contents) { *char_field_addr(offset) = (jint) contents; }
278 inline jint oopDesc::int_field(int offset) const { return *int_field_addr(offset); }
279 inline void oopDesc::int_field_put(int offset, jint contents) { *int_field_addr(offset) = contents; }
281 inline jshort oopDesc::short_field(int offset) const { return (jshort) *short_field_addr(offset); }
282 inline void oopDesc::short_field_put(int offset, jshort contents) { *short_field_addr(offset) = (jint) contents;}
284 inline jlong oopDesc::long_field(int offset) const { return *long_field_addr(offset); }
285 inline void oopDesc::long_field_put(int offset, jlong contents) { *long_field_addr(offset) = contents; }
287 inline jfloat oopDesc::float_field(int offset) const { return *float_field_addr(offset); }
288 inline void oopDesc::float_field_put(int offset, jfloat contents) { *float_field_addr(offset) = contents; }
290 inline jdouble oopDesc::double_field(int offset) const { return *double_field_addr(offset); }
291 inline void oopDesc::double_field_put(int offset, jdouble contents) { *double_field_addr(offset) = contents; }
293 inline address oopDesc::address_field(int offset) const { return *address_field_addr(offset); }
294 inline void oopDesc::address_field_put(int offset, address contents) { *address_field_addr(offset) = contents; }
296 inline oop oopDesc::obj_field_acquire(int offset) const {
297 return UseCompressedOops ?
298 decode_heap_oop((narrowOop)
299 OrderAccess::load_acquire(obj_field_addr<narrowOop>(offset)))
300 : decode_heap_oop((oop)
301 OrderAccess::load_ptr_acquire(obj_field_addr<oop>(offset)));
302 }
303 inline void oopDesc::release_obj_field_put(int offset, oop value) {
304 UseCompressedOops ?
305 oop_store((volatile narrowOop*)obj_field_addr<narrowOop>(offset), value) :
306 oop_store((volatile oop*) obj_field_addr<oop>(offset), value);
307 }
309 inline jbyte oopDesc::byte_field_acquire(int offset) const { return OrderAccess::load_acquire(byte_field_addr(offset)); }
310 inline void oopDesc::release_byte_field_put(int offset, jbyte contents) { OrderAccess::release_store(byte_field_addr(offset), contents); }
312 inline jboolean oopDesc::bool_field_acquire(int offset) const { return OrderAccess::load_acquire(bool_field_addr(offset)); }
313 inline void oopDesc::release_bool_field_put(int offset, jboolean contents) { OrderAccess::release_store(bool_field_addr(offset), contents); }
315 inline jchar oopDesc::char_field_acquire(int offset) const { return OrderAccess::load_acquire(char_field_addr(offset)); }
316 inline void oopDesc::release_char_field_put(int offset, jchar contents) { OrderAccess::release_store(char_field_addr(offset), contents); }
318 inline jint oopDesc::int_field_acquire(int offset) const { return OrderAccess::load_acquire(int_field_addr(offset)); }
319 inline void oopDesc::release_int_field_put(int offset, jint contents) { OrderAccess::release_store(int_field_addr(offset), contents); }
321 inline jshort oopDesc::short_field_acquire(int offset) const { return (jshort)OrderAccess::load_acquire(short_field_addr(offset)); }
322 inline void oopDesc::release_short_field_put(int offset, jshort contents) { OrderAccess::release_store(short_field_addr(offset), contents); }
324 inline jlong oopDesc::long_field_acquire(int offset) const { return OrderAccess::load_acquire(long_field_addr(offset)); }
325 inline void oopDesc::release_long_field_put(int offset, jlong contents) { OrderAccess::release_store(long_field_addr(offset), contents); }
327 inline jfloat oopDesc::float_field_acquire(int offset) const { return OrderAccess::load_acquire(float_field_addr(offset)); }
328 inline void oopDesc::release_float_field_put(int offset, jfloat contents) { OrderAccess::release_store(float_field_addr(offset), contents); }
330 inline jdouble oopDesc::double_field_acquire(int offset) const { return OrderAccess::load_acquire(double_field_addr(offset)); }
331 inline void oopDesc::release_double_field_put(int offset, jdouble contents) { OrderAccess::release_store(double_field_addr(offset), contents); }
333 inline int oopDesc::size_given_klass(Klass* klass) {
334 int lh = klass->layout_helper();
335 int s = lh >> LogHeapWordSize; // deliver size scaled by wordSize
337 // lh is now a value computed at class initialization that may hint
338 // at the size. For instances, this is positive and equal to the
339 // size. For arrays, this is negative and provides log2 of the
340 // array element size. For other oops, it is zero and thus requires
341 // a virtual call.
342 //
343 // We go to all this trouble because the size computation is at the
344 // heart of phase 2 of mark-compaction, and called for every object,
345 // alive or dead. So the speed here is equal in importance to the
346 // speed of allocation.
348 if (lh <= Klass::_lh_neutral_value) {
349 // The most common case is instances; fall through if so.
350 if (lh < Klass::_lh_neutral_value) {
351 // Second most common case is arrays. We have to fetch the
352 // length of the array, shift (multiply) it appropriately,
353 // up to wordSize, add the header, and align to object size.
354 size_t size_in_bytes;
355 #ifdef _M_IA64
356 // The Windows Itanium Aug 2002 SDK hoists this load above
357 // the check for s < 0. An oop at the end of the heap will
358 // cause an access violation if this load is performed on a non
359 // array oop. Making the reference volatile prohibits this.
360 // (%%% please explain by what magic the length is actually fetched!)
361 volatile int *array_length;
362 array_length = (volatile int *)( (intptr_t)this +
363 arrayOopDesc::length_offset_in_bytes() );
364 assert(array_length > 0, "Integer arithmetic problem somewhere");
365 // Put into size_t to avoid overflow.
366 size_in_bytes = (size_t) array_length;
367 size_in_bytes = size_in_bytes << Klass::layout_helper_log2_element_size(lh);
368 #else
369 size_t array_length = (size_t) ((arrayOop)this)->length();
370 size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
371 #endif
372 size_in_bytes += Klass::layout_helper_header_size(lh);
374 // This code could be simplified, but by keeping array_header_in_bytes
375 // in units of bytes and doing it this way we can round up just once,
376 // skipping the intermediate round to HeapWordSize. Cast the result
377 // of round_to to size_t to guarantee unsigned division == right shift.
378 s = (int)((size_t)round_to(size_in_bytes, MinObjAlignmentInBytes) /
379 HeapWordSize);
381 // UseParNewGC can change the length field of an "old copy" of an object
382 // array in the young gen so it indicates the stealable portion of
383 // an already copied array. This will cause the first disjunct below
384 // to fail if the sizes are computed across such a concurrent change.
385 // UseParNewGC also runs with promotion labs (which look like int
386 // filler arrays) which are subject to changing their declared size
387 // when finally retiring a PLAB; this also can cause the first disjunct
388 // to fail for another worker thread that is concurrently walking the block
389 // offset table. Both these invariant failures are benign for their
390 // current uses; we relax the assertion checking to cover these two cases below:
391 // is_objArray() && is_forwarded() // covers first scenario above
392 // || is_typeArray() // covers second scenario above
393 // If and when UseParallelGC uses the same obj array oop stealing/chunking
394 // technique, or when G1 is integrated (and currently uses this array chunking
395 // technique) we will need to suitably modify the assertion.
396 assert((s == klass->oop_size(this)) ||
397 (((UseParNewGC || UseParallelGC) &&
398 Universe::heap()->is_gc_active()) &&
399 (is_typeArray() ||
400 (is_objArray() && is_forwarded()))),
401 "wrong array object size");
402 } else {
403 // Must be zero, so bite the bullet and take the virtual call.
404 s = klass->oop_size(this);
405 }
406 }
408 assert(s % MinObjAlignment == 0, "alignment check");
409 assert(s > 0, "Bad size calculated");
410 return s;
411 }
414 inline int oopDesc::size() {
415 return size_given_klass(blueprint());
416 }
418 inline bool oopDesc::is_parsable() {
419 return blueprint()->oop_is_parsable(this);
420 }
422 inline void update_barrier_set(void* p, oop v) {
423 assert(oopDesc::bs() != NULL, "Uninitialized bs in oop!");
424 oopDesc::bs()->write_ref_field(p, v);
425 }
427 template <class T> inline void oop_store(T* p, oop v) {
428 if (always_do_update_barrier) {
429 oop_store((volatile T*)p, v);
430 } else {
431 oopDesc::encode_store_heap_oop(p, v);
432 update_barrier_set(p, v);
433 }
434 }
436 template <class T> inline void oop_store(volatile T* p, oop v) {
437 // Used by release_obj_field_put, so use release_store_ptr.
438 oopDesc::release_encode_store_heap_oop(p, v);
439 update_barrier_set((void*)p, v);
440 }
442 template <class T> inline void oop_store_without_check(T* p, oop v) {
443 // XXX YSR FIX ME!!!
444 if (always_do_update_barrier) {
445 oop_store(p, v);
446 } else {
447 assert(!Universe::heap()->barrier_set()->write_ref_needs_barrier(p, v),
448 "oop store without store check failed");
449 oopDesc::encode_store_heap_oop(p, v);
450 }
451 }
453 // When it absolutely has to get there.
454 template <class T> inline void oop_store_without_check(volatile T* p, oop v) {
455 // XXX YSR FIX ME!!!
456 if (always_do_update_barrier) {
457 oop_store(p, v);
458 } else {
459 assert(!Universe::heap()->barrier_set()->write_ref_needs_barrier((T*)p, v),
460 "oop store without store check failed");
461 oopDesc::release_encode_store_heap_oop(p, v);
462 }
463 }
465 // Should replace *addr = oop assignments where addr type depends on UseCompressedOops
466 // (without having to remember the function name this calls).
467 inline void oop_store_raw(HeapWord* addr, oop value) {
468 if (UseCompressedOops) {
469 oopDesc::encode_store_heap_oop((narrowOop*)addr, value);
470 } else {
471 oopDesc::encode_store_heap_oop((oop*)addr, value);
472 }
473 }
475 // Used only for markSweep, scavenging
476 inline bool oopDesc::is_gc_marked() const {
477 return mark()->is_marked();
478 }
480 inline bool oopDesc::is_locked() const {
481 return mark()->is_locked();
482 }
484 inline bool oopDesc::is_unlocked() const {
485 return mark()->is_unlocked();
486 }
488 inline bool oopDesc::has_bias_pattern() const {
489 return mark()->has_bias_pattern();
490 }
492 inline bool check_obj_alignment(oop obj) {
493 return (intptr_t)obj % MinObjAlignmentInBytes == 0;
494 }
497 // used only for asserts
498 inline bool oopDesc::is_oop(bool ignore_mark_word) const {
499 oop obj = (oop) this;
500 if (!check_obj_alignment(obj)) return false;
501 if (!Universe::heap()->is_in_reserved(obj)) return false;
502 // obj is aligned and accessible in heap
503 // try to find metaclass cycle safely without seg faulting on bad input
504 // we should reach klassKlassObj by following klass link at most 3 times
505 for (int i = 0; i < 3; i++) {
506 obj = obj->klass();
507 // klass should be aligned and in permspace
508 if (!check_obj_alignment(obj)) return false;
509 if (!Universe::heap()->is_in_permanent(obj)) return false;
510 }
511 if (obj != Universe::klassKlassObj()) {
512 // During a dump, the _klassKlassObj moved to a shared space.
513 if (DumpSharedSpaces && Universe::klassKlassObj()->is_shared()) {
514 return true;
515 }
516 return false;
517 }
519 // Header verification: the mark is typically non-NULL. If we're
520 // at a safepoint, it must not be null.
521 // Outside of a safepoint, the header could be changing (for example,
522 // another thread could be inflating a lock on this object).
523 if (ignore_mark_word) {
524 return true;
525 }
526 if (mark() != NULL) {
527 return true;
528 }
529 return !SafepointSynchronize::is_at_safepoint();
530 }
533 // used only for asserts
534 inline bool oopDesc::is_oop_or_null(bool ignore_mark_word) const {
535 return this == NULL ? true : is_oop(ignore_mark_word);
536 }
538 #ifndef PRODUCT
539 // used only for asserts
540 inline bool oopDesc::is_unlocked_oop() const {
541 if (!Universe::heap()->is_in_reserved(this)) return false;
542 return mark()->is_unlocked();
543 }
544 #endif // PRODUCT
546 inline void oopDesc::follow_header() {
547 if (UseCompressedOops) {
548 MarkSweep::mark_and_push(compressed_klass_addr());
549 } else {
550 MarkSweep::mark_and_push(klass_addr());
551 }
552 }
554 inline void oopDesc::follow_contents(void) {
555 assert (is_gc_marked(), "should be marked");
556 blueprint()->oop_follow_contents(this);
557 }
560 // Used by scavengers
562 inline bool oopDesc::is_forwarded() const {
563 // The extra heap check is needed since the obj might be locked, in which case the
564 // mark would point to a stack location and have the sentinel bit cleared
565 return mark()->is_marked();
566 }
568 // Used by scavengers
569 inline void oopDesc::forward_to(oop p) {
570 assert(Universe::heap()->is_in_reserved(p),
571 "forwarding to something not in heap");
572 markOop m = markOopDesc::encode_pointer_as_mark(p);
573 assert(m->decode_pointer() == p, "encoding must be reversable");
574 set_mark(m);
575 }
577 // Used by parallel scavengers
578 inline bool oopDesc::cas_forward_to(oop p, markOop compare) {
579 assert(Universe::heap()->is_in_reserved(p),
580 "forwarding to something not in heap");
581 markOop m = markOopDesc::encode_pointer_as_mark(p);
582 assert(m->decode_pointer() == p, "encoding must be reversable");
583 return cas_set_mark(m, compare) == compare;
584 }
586 // Note that the forwardee is not the same thing as the displaced_mark.
587 // The forwardee is used when copying during scavenge and mark-sweep.
588 // It does need to clear the low two locking- and GC-related bits.
589 inline oop oopDesc::forwardee() const {
590 return (oop) mark()->decode_pointer();
591 }
593 inline bool oopDesc::has_displaced_mark() const {
594 return mark()->has_displaced_mark_helper();
595 }
597 inline markOop oopDesc::displaced_mark() const {
598 return mark()->displaced_mark_helper();
599 }
601 inline void oopDesc::set_displaced_mark(markOop m) {
602 mark()->set_displaced_mark_helper(m);
603 }
605 // The following method needs to be MT safe.
606 inline int oopDesc::age() const {
607 assert(!is_forwarded(), "Attempt to read age from forwarded mark");
608 if (has_displaced_mark()) {
609 return displaced_mark()->age();
610 } else {
611 return mark()->age();
612 }
613 }
615 inline void oopDesc::incr_age() {
616 assert(!is_forwarded(), "Attempt to increment age of forwarded mark");
617 if (has_displaced_mark()) {
618 set_displaced_mark(displaced_mark()->incr_age());
619 } else {
620 set_mark(mark()->incr_age());
621 }
622 }
625 inline intptr_t oopDesc::identity_hash() {
626 // Fast case; if the object is unlocked and the hash value is set, no locking is needed
627 // Note: The mark must be read into local variable to avoid concurrent updates.
628 markOop mrk = mark();
629 if (mrk->is_unlocked() && !mrk->has_no_hash()) {
630 return mrk->hash();
631 } else if (mrk->is_marked()) {
632 return mrk->hash();
633 } else {
634 return slow_identity_hash();
635 }
636 }
638 inline void oopDesc::oop_iterate_header(OopClosure* blk) {
639 if (UseCompressedOops) {
640 blk->do_oop(compressed_klass_addr());
641 } else {
642 blk->do_oop(klass_addr());
643 }
644 }
646 inline void oopDesc::oop_iterate_header(OopClosure* blk, MemRegion mr) {
647 if (UseCompressedOops) {
648 if (mr.contains(compressed_klass_addr())) {
649 blk->do_oop(compressed_klass_addr());
650 }
651 } else {
652 if (mr.contains(klass_addr())) blk->do_oop(klass_addr());
653 }
654 }
656 inline int oopDesc::adjust_pointers() {
657 debug_only(int check_size = size());
658 int s = blueprint()->oop_adjust_pointers(this);
659 assert(s == check_size, "should be the same");
660 return s;
661 }
663 inline void oopDesc::adjust_header() {
664 if (UseCompressedOops) {
665 MarkSweep::adjust_pointer(compressed_klass_addr());
666 } else {
667 MarkSweep::adjust_pointer(klass_addr());
668 }
669 }
671 #define OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
672 \
673 inline int oopDesc::oop_iterate(OopClosureType* blk) { \
674 SpecializationStats::record_call(); \
675 return blueprint()->oop_oop_iterate##nv_suffix(this, blk); \
676 } \
677 \
678 inline int oopDesc::oop_iterate(OopClosureType* blk, MemRegion mr) { \
679 SpecializationStats::record_call(); \
680 return blueprint()->oop_oop_iterate##nv_suffix##_m(this, blk, mr); \
681 }
683 ALL_OOP_OOP_ITERATE_CLOSURES_1(OOP_ITERATE_DEFN)
684 ALL_OOP_OOP_ITERATE_CLOSURES_3(OOP_ITERATE_DEFN)
687 inline bool oopDesc::is_shared() const {
688 return CompactingPermGenGen::is_shared(this);
689 }
691 inline bool oopDesc::is_shared_readonly() const {
692 return CompactingPermGenGen::is_shared_readonly(this);
693 }
695 inline bool oopDesc::is_shared_readwrite() const {
696 return CompactingPermGenGen::is_shared_readwrite(this);
697 }