rev 7084 : [mq]: demacro
1 /* 2 * Copyright (c) 2000, 2012, 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. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_MEMORY_SPACE_INLINE_HPP 26 #define SHARE_VM_MEMORY_SPACE_INLINE_HPP 27 28 #include "gc_implementation/shared/liveRange.hpp" 29 #include "gc_implementation/shared/markSweep.inline.hpp" 30 #include "gc_implementation/shared/spaceDecorator.hpp" 31 #include "gc_interface/collectedHeap.hpp" 32 #include "memory/space.hpp" 33 #include "memory/universe.hpp" 34 #include "runtime/prefetch.inline.hpp" 35 #include "runtime/safepoint.hpp" 36 37 inline HeapWord* Space::block_start(const void* p) { 38 return block_start_const(p); 39 } 40 41 inline HeapWord* OffsetTableContigSpace::allocate(size_t size) { 42 HeapWord* res = ContiguousSpace::allocate(size); 43 if (res != NULL) { 44 _offsets.alloc_block(res, size); 45 } 46 return res; 47 } 48 49 // Because of the requirement of keeping "_offsets" up to date with the 50 // allocations, we sequentialize these with a lock. Therefore, best if 51 // this is used for larger LAB allocations only. 52 inline HeapWord* OffsetTableContigSpace::par_allocate(size_t size) { 53 MutexLocker x(&_par_alloc_lock); 54 // This ought to be just "allocate", because of the lock above, but that 55 // ContiguousSpace::allocate asserts that either the allocating thread 56 // holds the heap lock or it is the VM thread and we're at a safepoint. 57 // The best I (dld) could figure was to put a field in ContiguousSpace 58 // meaning "locking at safepoint taken care of", and set/reset that 59 // here. But this will do for now, especially in light of the comment 60 // above. Perhaps in the future some lock-free manner of keeping the 61 // coordination. 62 HeapWord* res = ContiguousSpace::par_allocate(size); 63 if (res != NULL) { 64 _offsets.alloc_block(res, size); 65 } 66 return res; 67 } 68 69 inline HeapWord* 70 OffsetTableContigSpace::block_start_const(const void* p) const { 71 return _offsets.block_start(p); 72 } 73 74 template <class SpaceType> 75 inline void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp) { 76 // Compute the new addresses for the live objects and store it in the mark 77 // Used by universe::mark_sweep_phase2() 78 HeapWord* compact_top; // This is where we are currently compacting to. 79 80 // We're sure to be here before any objects are compacted into this 81 // space, so this is a good time to initialize this: 82 space->set_compaction_top(space->bottom()); 83 84 if (cp->space == NULL) { 85 assert(cp->gen != NULL, "need a generation"); 86 assert(cp->threshold == NULL, "just checking"); 87 assert(cp->gen->first_compaction_space() == space, "just checking"); 88 cp->space = cp->gen->first_compaction_space(); 89 compact_top = cp->space->bottom(); 90 cp->space->set_compaction_top(compact_top); 91 cp->threshold = cp->space->initialize_threshold(); 92 } else { 93 compact_top = cp->space->compaction_top(); 94 } 95 96 // We allow some amount of garbage towards the bottom of the space, so 97 // we don't start compacting before there is a significant gain to be made.\ 98 // Occasionally, we want to ensure a full compaction, which is determined 99 // by the MarkSweepAlwaysCompactCount parameter. 100 uint invocations = MarkSweep::total_invocations(); 101 bool skip_dead = ((invocations % MarkSweepAlwaysCompactCount) != 0); 102 103 size_t allowed_deadspace = 0; 104 if (skip_dead) { 105 const size_t ratio = space->allowed_dead_ratio(); 106 allowed_deadspace = (space->capacity() * ratio / 100) / HeapWordSize; 107 } 108 109 HeapWord* q = space->bottom(); 110 HeapWord* t = space->scan_limit(); 111 112 HeapWord* end_of_live= q; // One byte beyond the last byte of the last 113 // live object. 114 HeapWord* first_dead = space->end(); // The first dead object. 115 LiveRange* liveRange = NULL; // The current live range, recorded in the 116 // first header of preceding free area. 117 space->_first_dead = first_dead; 118 119 const intx interval = PrefetchScanIntervalInBytes; 120 121 while (q < t) { 122 assert(!space->scanned_block_is_obj(q) || 123 oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() || 124 oop(q)->mark()->has_bias_pattern(), 125 "these are the only valid states during a mark sweep"); 126 if (space->scanned_block_is_obj(q) && oop(q)->is_gc_marked()) { 127 // prefetch beyond q 128 Prefetch::write(q, interval); 129 size_t size = space->scanned_block_size(q); 130 compact_top = cp->space->forward(oop(q), size, cp, compact_top); 131 q += size; 132 end_of_live = q; 133 } else { 134 // run over all the contiguous dead objects 135 HeapWord* end = q; 136 do { 137 // prefetch beyond end 138 Prefetch::write(end, interval); 139 end += space->scanned_block_size(end); 140 } while (end < t && (!space->scanned_block_is_obj(end) || !oop(end)->is_gc_marked())); 141 142 // see if we might want to pretend this object is alive so that 143 // we don't have to compact quite as often. 144 if (allowed_deadspace > 0 && q == compact_top) { 145 size_t sz = pointer_delta(end, q); 146 if (space->insert_deadspace(allowed_deadspace, q, sz)) { 147 compact_top = cp->space->forward(oop(q), sz, cp, compact_top); 148 q = end; 149 end_of_live = end; 150 continue; 151 } 152 } 153 154 // otherwise, it really is a free region. 155 156 // for the previous LiveRange, record the end of the live objects. 157 if (liveRange) { 158 liveRange->set_end(q); 159 } 160 161 // record the current LiveRange object. 162 // liveRange->start() is overlaid on the mark word. 163 liveRange = (LiveRange*)q; 164 liveRange->set_start(end); 165 liveRange->set_end(end); 166 167 // see if this is the first dead region. 168 if (q < first_dead) { 169 first_dead = q; 170 } 171 172 // move on to the next object 173 q = end; 174 } 175 } 176 177 assert(q == t, "just checking"); 178 if (liveRange != NULL) { 179 liveRange->set_end(q); 180 } 181 space->_end_of_live = end_of_live; 182 if (end_of_live < first_dead) { 183 first_dead = end_of_live; 184 } 185 space->_first_dead = first_dead; 186 187 // save the compaction_top of the compaction space. 188 cp->space->set_compaction_top(compact_top); 189 } 190 191 template <class SpaceType> 192 inline void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space) { 193 // adjust all the interior pointers to point at the new locations of objects 194 // Used by MarkSweep::mark_sweep_phase3() 195 196 HeapWord* q = space->bottom(); 197 HeapWord* t = space->_end_of_live; // Established by "prepare_for_compaction". 198 199 assert(space->_first_dead <= space->_end_of_live, "Stands to reason, no?"); 200 201 if (q < t && space->_first_dead > q && !oop(q)->is_gc_marked()) { 202 // we have a chunk of the space which hasn't moved and we've 203 // reinitialized the mark word during the previous pass, so we can't 204 // use is_gc_marked for the traversal. 205 HeapWord* end = space->_first_dead; 206 207 while (q < end) { 208 // I originally tried to conjoin "block_start(q) == q" to the 209 // assertion below, but that doesn't work, because you can't 210 // accurately traverse previous objects to get to the current one 211 // after their pointers have been 212 // updated, until the actual compaction is done. dld, 4/00 213 assert(space->scanned_block_is_obj(q), "should be at block boundaries, and should be looking at objs"); 214 215 // point all the oops to the new location 216 size_t size = oop(q)->adjust_pointers(); 217 size = space->adjust_obj_size(size); 218 219 q += size; 220 } 221 222 if (space->_first_dead == t) { 223 q = t; 224 } else { 225 // $$$ This is funky. Using this to read the previously written 226 // LiveRange. See also use below. 227 q = (HeapWord*)oop(space->_first_dead)->mark()->decode_pointer(); 228 } 229 } 230 231 const intx interval = PrefetchScanIntervalInBytes; 232 233 debug_only(HeapWord* prev_q = NULL); 234 while (q < t) { 235 // prefetch beyond q 236 Prefetch::write(q, interval); 237 if (oop(q)->is_gc_marked()) { 238 // q is alive 239 // point all the oops to the new location 240 size_t size = oop(q)->adjust_pointers(); 241 size = space->adjust_obj_size(size); 242 debug_only(prev_q = q); 243 q += size; 244 } else { 245 // q is not a live object, so its mark should point at the next 246 // live object 247 debug_only(prev_q = q); 248 q = (HeapWord*) oop(q)->mark()->decode_pointer(); 249 assert(q > prev_q, "we should be moving forward through memory"); 250 } 251 } 252 253 assert(q == t, "just checking"); 254 } 255 256 template <class SpaceType> 257 inline void CompactibleSpace::scan_and_compact(SpaceType* space) { 258 // Copy all live objects to their new location 259 // Used by MarkSweep::mark_sweep_phase4() 260 261 HeapWord* q = space->bottom(); 262 HeapWord* const t = space->_end_of_live; 263 debug_only(HeapWord* prev_q = NULL); 264 265 if (q < t && space->_first_dead > q && !oop(q)->is_gc_marked()) { 266 #ifdef ASSERT // Debug only 267 // we have a chunk of the space which hasn't moved and we've reinitialized 268 // the mark word during the previous pass, so we can't use is_gc_marked for 269 // the traversal. 270 HeapWord* const end = space->_first_dead; 271 272 while (q < end) { 273 size_t size = space->obj_size(q); 274 assert(!oop(q)->is_gc_marked(), "should be unmarked (special dense prefix handling)"); 275 prev_q = q; 276 q += size; 277 } 278 #endif 279 280 if (space->_first_dead == t) { 281 q = t; 282 } else { 283 // $$$ Funky 284 q = (HeapWord*) oop(space->_first_dead)->mark()->decode_pointer(); 285 } 286 } 287 288 const intx scan_interval = PrefetchScanIntervalInBytes; 289 const intx copy_interval = PrefetchCopyIntervalInBytes; 290 while (q < t) { 291 if (!oop(q)->is_gc_marked()) { 292 // mark is pointer to next marked oop 293 debug_only(prev_q = q); 294 q = (HeapWord*) oop(q)->mark()->decode_pointer(); 295 assert(q > prev_q, "we should be moving forward through memory"); 296 } else { 297 // prefetch beyond q 298 Prefetch::read(q, scan_interval); 299 300 // size and destination 301 size_t size = space->obj_size(q); 302 HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); 303 304 // prefetch beyond compaction_top 305 Prefetch::write(compaction_top, copy_interval); 306 307 // copy object and reinit its mark 308 assert(q != compaction_top, "everything in this pass should be moving"); 309 Copy::aligned_conjoint_words(q, compaction_top, size); 310 oop(compaction_top)->init_mark(); 311 assert(oop(compaction_top)->klass() != NULL, "should have a class"); 312 313 debug_only(prev_q = q); 314 q += size; 315 } 316 } 317 318 // Let's remember if we were empty before we did the compaction. 319 bool was_empty = space->used_region().is_empty(); 320 // Reset space after compaction is complete 321 space->reset_after_compaction(); 322 // We do this clear, below, since it has overloaded meanings for some 323 // space subtypes. For example, OffsetTableContigSpace's that were 324 // compacted into will have had their offset table thresholds updated 325 // continuously, but those that weren't need to have their thresholds 326 // re-initialized. Also mangles unused area for debugging. 327 if (space->used_region().is_empty()) { 328 if (!was_empty) space->clear(SpaceDecorator::Mangle); 329 } else { 330 if (ZapUnusedHeapArea) space->mangle_unused_area(); 331 } 332 } 333 #endif // SHARE_VM_MEMORY_SPACE_INLINE_HPP --- EOF ---