space.hpp revision 13249:a2753984d2c1
1174294Sobrien/* 2131702Smbr * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved. 3174294Sobrien * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4174294Sobrien * 5174294Sobrien * This code is free software; you can redistribute it and/or modify it 6131702Smbr * under the terms of the GNU General Public License version 2 only, as 7174294Sobrien * published by the Free Software Foundation. 8131702Smbr * 9174294Sobrien * This code is distributed in the hope that it will be useful, but WITHOUT 10174294Sobrien * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11131702Smbr * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12174294Sobrien * version 2 for more details (a copy is included in the LICENSE file that 13174294Sobrien * accompanied this code). 14131702Smbr * 15174294Sobrien * You should have received a copy of the GNU General Public License version 16174294Sobrien * 2 along with this work; if not, write to the Free Software Foundation, 17131702Smbr * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18174294Sobrien * 19131702Smbr * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20174294Sobrien * or visit www.oracle.com if you need additional information or have any 21174294Sobrien * questions. 22174294Sobrien * 23131702Smbr */ 24174294Sobrien 25131702Smbr#ifndef SHARE_VM_GC_SHARED_SPACE_HPP 26174294Sobrien#define SHARE_VM_GC_SHARED_SPACE_HPP 27174294Sobrien 28174294Sobrien#include "gc/shared/blockOffsetTable.hpp" 29174294Sobrien#include "gc/shared/cardTableModRefBS.hpp" 30174294Sobrien#include "gc/shared/workgroup.hpp" 31174294Sobrien#include "memory/allocation.hpp" 32174294Sobrien#include "memory/iterator.hpp" 33174294Sobrien#include "memory/memRegion.hpp" 34174294Sobrien#include "oops/markOop.hpp" 35174294Sobrien#include "runtime/mutexLocker.hpp" 36174294Sobrien#include "utilities/align.hpp" 37174294Sobrien#include "utilities/macros.hpp" 38174294Sobrien 39174294Sobrien// A space is an abstraction for the "storage units" backing 40174294Sobrien// up the generation abstraction. It includes specific 41174294Sobrien// implementations for keeping track of free and used space, 42174294Sobrien// for iterating over objects and free blocks, etc. 43174294Sobrien 44174294Sobrien// Forward decls. 45174294Sobrienclass Space; 46174294Sobrienclass BlockOffsetArray; 47174294Sobrienclass BlockOffsetArrayContigSpace; 48174294Sobrienclass Generation; 49174294Sobrienclass CompactibleSpace; 50174294Sobrienclass BlockOffsetTable; 51174294Sobrienclass CardTableRS; 52174294Sobrienclass DirtyCardToOopClosure; 53174294Sobrien 54174294Sobrien// A Space describes a heap area. Class Space is an abstract 55174294Sobrien// base class. 56174294Sobrien// 57174294Sobrien// Space supports allocation, size computation and GC support is provided. 58174294Sobrien// 59174294Sobrien// Invariant: bottom() and end() are on page_size boundaries and 60174294Sobrien// bottom() <= top() <= end() 61174294Sobrien// top() is inclusive and end() is exclusive. 62174294Sobrien 63174294Sobrienclass Space: public CHeapObj<mtGC> { 64174294Sobrien friend class VMStructs; 65174294Sobrien protected: 66174294Sobrien HeapWord* _bottom; 67174294Sobrien HeapWord* _end; 68174294Sobrien 69174294Sobrien // Used in support of save_marks() 70174294Sobrien HeapWord* _saved_mark_word; 71174294Sobrien 72174294Sobrien // A sequential tasks done structure. This supports 73174294Sobrien // parallel GC, where we have threads dynamically 74174294Sobrien // claiming sub-tasks from a larger parallel task. 75174294Sobrien SequentialSubTasksDone _par_seq_tasks; 76174294Sobrien 77174294Sobrien Space(): 78174294Sobrien _bottom(NULL), _end(NULL) { } 79174294Sobrien 80174294Sobrien public: 81174294Sobrien // Accessors 82174294Sobrien HeapWord* bottom() const { return _bottom; } 83174294Sobrien HeapWord* end() const { return _end; } 84174294Sobrien virtual void set_bottom(HeapWord* value) { _bottom = value; } 85174294Sobrien virtual void set_end(HeapWord* value) { _end = value; } 86174294Sobrien 87174294Sobrien virtual HeapWord* saved_mark_word() const { return _saved_mark_word; } 88174294Sobrien 89174294Sobrien void set_saved_mark_word(HeapWord* p) { _saved_mark_word = p; } 90174294Sobrien 91174294Sobrien // Returns true if this object has been allocated since a 92174294Sobrien // generation's "save_marks" call. 93174294Sobrien virtual bool obj_allocated_since_save_marks(const oop obj) const { 94174294Sobrien return (HeapWord*)obj >= saved_mark_word(); 95174294Sobrien } 96174294Sobrien 97174294Sobrien virtual MemRegionClosure* preconsumptionDirtyCardClosure() const { 98174294Sobrien return NULL; 99174294Sobrien } 100174294Sobrien 101174294Sobrien // Returns a subregion of the space containing only the allocated objects in 102174294Sobrien // the space. 103174294Sobrien virtual MemRegion used_region() const = 0; 104174294Sobrien 105174294Sobrien // Returns a region that is guaranteed to contain (at least) all objects 106174294Sobrien // allocated at the time of the last call to "save_marks". If the space 107174294Sobrien // initializes its DirtyCardToOopClosure's specifying the "contig" option 108174294Sobrien // (that is, if the space is contiguous), then this region must contain only 109174294Sobrien // such objects: the memregion will be from the bottom of the region to the 110174294Sobrien // saved mark. Otherwise, the "obj_allocated_since_save_marks" method of 111174294Sobrien // the space must distinguish between objects in the region allocated before 112174294Sobrien // and after the call to save marks. 113174294Sobrien MemRegion used_region_at_save_marks() const { 114174294Sobrien return MemRegion(bottom(), saved_mark_word()); 115174294Sobrien } 116174294Sobrien 117174294Sobrien // Initialization. 118174294Sobrien // "initialize" should be called once on a space, before it is used for 119174294Sobrien // any purpose. The "mr" arguments gives the bounds of the space, and 120174294Sobrien // the "clear_space" argument should be true unless the memory in "mr" is 121174294Sobrien // known to be zeroed. 122174294Sobrien virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space); 123174294Sobrien 124174294Sobrien // The "clear" method must be called on a region that may have 125174294Sobrien // had allocation performed in it, but is now to be considered empty. 126174294Sobrien virtual void clear(bool mangle_space); 127174294Sobrien 128174294Sobrien // For detecting GC bugs. Should only be called at GC boundaries, since 129174294Sobrien // some unused space may be used as scratch space during GC's. 130174294Sobrien // We also call this when expanding a space to satisfy an allocation 131174294Sobrien // request. See bug #4668531 132174294Sobrien virtual void mangle_unused_area() = 0; 133174294Sobrien virtual void mangle_unused_area_complete() = 0; 134174294Sobrien 135174294Sobrien // Testers 136174294Sobrien bool is_empty() const { return used() == 0; } 137174294Sobrien bool not_empty() const { return used() > 0; } 138174294Sobrien 139174294Sobrien // Returns true iff the given the space contains the 140174294Sobrien // given address as part of an allocated object. For 141174294Sobrien // certain kinds of spaces, this might be a potentially 142174294Sobrien // expensive operation. To prevent performance problems 143174294Sobrien // on account of its inadvertent use in product jvm's, 144174294Sobrien // we restrict its use to assertion checks only. 145174294Sobrien bool is_in(const void* p) const { 146174294Sobrien return used_region().contains(p); 147174294Sobrien } 148174294Sobrien 149174294Sobrien // Returns true iff the given reserved memory of the space contains the 150174294Sobrien // given address. 151174294Sobrien bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; } 152174294Sobrien 153174294Sobrien // Returns true iff the given block is not allocated. 154174294Sobrien virtual bool is_free_block(const HeapWord* p) const = 0; 155174294Sobrien 156174294Sobrien // Test whether p is double-aligned 157174294Sobrien static bool is_aligned(void* p) { 158174294Sobrien return ::is_aligned(p, sizeof(double)); 159174294Sobrien } 160174294Sobrien 161174294Sobrien // Size computations. Sizes are in bytes. 162174294Sobrien size_t capacity() const { return byte_size(bottom(), end()); } 163174294Sobrien virtual size_t used() const = 0; 164174294Sobrien virtual size_t free() const = 0; 165174294Sobrien 166174294Sobrien // Iterate over all the ref-containing fields of all objects in the 167174294Sobrien // space, calling "cl.do_oop" on each. Fields in objects allocated by 168174294Sobrien // applications of the closure are not included in the iteration. 169174294Sobrien virtual void oop_iterate(ExtendedOopClosure* cl); 170174294Sobrien 171174294Sobrien // Iterate over all objects in the space, calling "cl.do_object" on 172174294Sobrien // each. Objects allocated by applications of the closure are not 173174294Sobrien // included in the iteration. 174174294Sobrien virtual void object_iterate(ObjectClosure* blk) = 0; 175174294Sobrien // Similar to object_iterate() except only iterates over 176174294Sobrien // objects whose internal references point to objects in the space. 177174294Sobrien virtual void safe_object_iterate(ObjectClosure* blk) = 0; 178174294Sobrien 179174294Sobrien // Create and return a new dirty card to oop closure. Can be 180174294Sobrien // overridden to return the appropriate type of closure 181174294Sobrien // depending on the type of space in which the closure will 182174294Sobrien // operate. ResourceArea allocated. 183174294Sobrien virtual DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl, 184174294Sobrien CardTableModRefBS::PrecisionStyle precision, 185174294Sobrien HeapWord* boundary, 186174294Sobrien bool parallel); 187174294Sobrien 188174294Sobrien // If "p" is in the space, returns the address of the start of the 189174294Sobrien // "block" that contains "p". We say "block" instead of "object" since 190174294Sobrien // some heaps may not pack objects densely; a chunk may either be an 191174294Sobrien // object or a non-object. If "p" is not in the space, return NULL. 192174294Sobrien virtual HeapWord* block_start_const(const void* p) const = 0; 193174294Sobrien 194174294Sobrien // The non-const version may have benevolent side effects on the data 195174294Sobrien // structure supporting these calls, possibly speeding up future calls. 196174294Sobrien // The default implementation, however, is simply to call the const 197174294Sobrien // version. 198174294Sobrien virtual HeapWord* block_start(const void* p); 199174294Sobrien 200174294Sobrien // Requires "addr" to be the start of a chunk, and returns its size. 201174294Sobrien // "addr + size" is required to be the start of a new chunk, or the end 202174294Sobrien // of the active area of the heap. 203174294Sobrien virtual size_t block_size(const HeapWord* addr) const = 0; 204174294Sobrien 205174294Sobrien // Requires "addr" to be the start of a block, and returns "TRUE" iff 206174294Sobrien // the block is an object. 207174294Sobrien virtual bool block_is_obj(const HeapWord* addr) const = 0; 208174294Sobrien 209174294Sobrien // Requires "addr" to be the start of a block, and returns "TRUE" iff 210174294Sobrien // the block is an object and the object is alive. 211174294Sobrien virtual bool obj_is_alive(const HeapWord* addr) const; 212174294Sobrien 213174294Sobrien // Allocation (return NULL if full). Assumes the caller has established 214174294Sobrien // mutually exclusive access to the space. 215174294Sobrien virtual HeapWord* allocate(size_t word_size) = 0; 216174294Sobrien 217174294Sobrien // Allocation (return NULL if full). Enforces mutual exclusion internally. 218174294Sobrien virtual HeapWord* par_allocate(size_t word_size) = 0; 219174294Sobrien 220174294Sobrien // Mark-sweep-compact support: all spaces can update pointers to objects 221174294Sobrien // moving as a part of compaction. 222174294Sobrien virtual void adjust_pointers() = 0; 223174294Sobrien 224174294Sobrien virtual void print() const; 225174294Sobrien virtual void print_on(outputStream* st) const; 226174294Sobrien virtual void print_short() const; 227174294Sobrien virtual void print_short_on(outputStream* st) const; 228174294Sobrien 229174294Sobrien 230174294Sobrien // Accessor for parallel sequential tasks. 231174294Sobrien SequentialSubTasksDone* par_seq_tasks() { return &_par_seq_tasks; } 232174294Sobrien 233174294Sobrien // IF "this" is a ContiguousSpace, return it, else return NULL. 234174294Sobrien virtual ContiguousSpace* toContiguousSpace() { 235174294Sobrien return NULL; 236174294Sobrien } 237174294Sobrien 238174294Sobrien // Debugging 239174294Sobrien virtual void verify() const = 0; 240174294Sobrien}; 241174294Sobrien 242174294Sobrien// A MemRegionClosure (ResourceObj) whose "do_MemRegion" function applies an 243174294Sobrien// OopClosure to (the addresses of) all the ref-containing fields that could 244174294Sobrien// be modified by virtue of the given MemRegion being dirty. (Note that 245174294Sobrien// because of the imprecise nature of the write barrier, this may iterate 246174294Sobrien// over oops beyond the region.) 247174294Sobrien// This base type for dirty card to oop closures handles memory regions 248174294Sobrien// in non-contiguous spaces with no boundaries, and should be sub-classed 249174294Sobrien// to support other space types. See ContiguousDCTOC for a sub-class 250174294Sobrien// that works with ContiguousSpaces. 251174294Sobrien 252174294Sobrienclass DirtyCardToOopClosure: public MemRegionClosureRO { 253174294Sobrienprotected: 254174294Sobrien ExtendedOopClosure* _cl; 255174294Sobrien Space* _sp; 256174294Sobrien CardTableModRefBS::PrecisionStyle _precision; 257174294Sobrien HeapWord* _boundary; // If non-NULL, process only non-NULL oops 258174294Sobrien // pointing below boundary. 259174294Sobrien HeapWord* _min_done; // ObjHeadPreciseArray precision requires 260174294Sobrien // a downwards traversal; this is the 261174294Sobrien // lowest location already done (or, 262174294Sobrien // alternatively, the lowest address that 263174294Sobrien // shouldn't be done again. NULL means infinity.) 264174294Sobrien NOT_PRODUCT(HeapWord* _last_bottom;) 265174294Sobrien NOT_PRODUCT(HeapWord* _last_explicit_min_done;) 266174294Sobrien 267174294Sobrien // Get the actual top of the area on which the closure will 268174294Sobrien // operate, given where the top is assumed to be (the end of the 269174294Sobrien // memory region passed to do_MemRegion) and where the object 270174294Sobrien // at the top is assumed to start. For example, an object may 271174294Sobrien // start at the top but actually extend past the assumed top, 272174294Sobrien // in which case the top becomes the end of the object. 273174294Sobrien virtual HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj); 274174294Sobrien 275174294Sobrien // Walk the given memory region from bottom to (actual) top 276174294Sobrien // looking for objects and applying the oop closure (_cl) to 277174294Sobrien // them. The base implementation of this treats the area as 278174294Sobrien // blocks, where a block may or may not be an object. Sub- 279174294Sobrien // classes should override this to provide more accurate 280174294Sobrien // or possibly more efficient walking. 281174294Sobrien virtual void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top); 282174294Sobrien 283174294Sobrienpublic: 284174294Sobrien DirtyCardToOopClosure(Space* sp, ExtendedOopClosure* cl, 285174294Sobrien CardTableModRefBS::PrecisionStyle precision, 286174294Sobrien HeapWord* boundary) : 287174294Sobrien _sp(sp), _cl(cl), _precision(precision), _boundary(boundary), 288174294Sobrien _min_done(NULL) { 289174294Sobrien NOT_PRODUCT(_last_bottom = NULL); 290174294Sobrien NOT_PRODUCT(_last_explicit_min_done = NULL); 291174294Sobrien } 292174294Sobrien 293174294Sobrien void do_MemRegion(MemRegion mr); 294174294Sobrien 295174294Sobrien void set_min_done(HeapWord* min_done) { 296174294Sobrien _min_done = min_done; 297174294Sobrien NOT_PRODUCT(_last_explicit_min_done = _min_done); 298174294Sobrien } 299174294Sobrien#ifndef PRODUCT 300174294Sobrien void set_last_bottom(HeapWord* last_bottom) { 301174294Sobrien _last_bottom = last_bottom; 302174294Sobrien } 303174294Sobrien#endif 304174294Sobrien}; 305174294Sobrien 306174294Sobrien// A structure to represent a point at which objects are being copied 307174294Sobrien// during compaction. 308174294Sobrienclass CompactPoint : public StackObj { 309174294Sobrienpublic: 310174294Sobrien Generation* gen; 311174294Sobrien CompactibleSpace* space; 312174294Sobrien HeapWord* threshold; 313174294Sobrien 314174294Sobrien CompactPoint(Generation* g = NULL) : 315174294Sobrien gen(g), space(NULL), threshold(0) {} 316174294Sobrien}; 317174294Sobrien 318174294Sobrien// A space that supports compaction operations. This is usually, but not 319174294Sobrien// necessarily, a space that is normally contiguous. But, for example, a 320174294Sobrien// free-list-based space whose normal collection is a mark-sweep without 321174294Sobrien// compaction could still support compaction in full GC's. 322174294Sobrien// 323174294Sobrien// The compaction operations are implemented by the 324174294Sobrien// scan_and_{adjust_pointers,compact,forward} function templates. 325174294Sobrien// The following are, non-virtual, auxiliary functions used by these function templates: 326174294Sobrien// - scan_limit() 327174294Sobrien// - scanned_block_is_obj() 328174294Sobrien// - scanned_block_size() 329174294Sobrien// - adjust_obj_size() 330174294Sobrien// - obj_size() 331174294Sobrien// These functions are to be used exclusively by the scan_and_* function templates, 332174294Sobrien// and must be defined for all (non-abstract) subclasses of CompactibleSpace. 333174294Sobrien// 334174294Sobrien// NOTE: Any subclasses to CompactibleSpace wanting to change/define the behavior 335174294Sobrien// in any of the auxiliary functions must also override the corresponding 336174294Sobrien// prepare_for_compaction/adjust_pointers/compact functions using them. 337174294Sobrien// If not, such changes will not be used or have no effect on the compaction operations. 338174294Sobrien// 339174294Sobrien// This translates to the following dependencies: 340174294Sobrien// Overrides/definitions of 341174294Sobrien// - scan_limit 342174294Sobrien// - scanned_block_is_obj 343174294Sobrien// - scanned_block_size 344174294Sobrien// require override/definition of prepare_for_compaction(). 345174294Sobrien// Similar dependencies exist between 346174294Sobrien// - adjust_obj_size and adjust_pointers() 347174294Sobrien// - obj_size and compact(). 348174294Sobrien// 349174294Sobrien// Additionally, this also means that changes to block_size() or block_is_obj() that 350174294Sobrien// should be effective during the compaction operations must provide a corresponding 351174294Sobrien// definition of scanned_block_size/scanned_block_is_obj respectively. 352174294Sobrienclass CompactibleSpace: public Space { 353174294Sobrien friend class VMStructs; 354174294Sobrien friend class CompactibleFreeListSpace; 355174294Sobrienprivate: 356174294Sobrien HeapWord* _compaction_top; 357174294Sobrien CompactibleSpace* _next_compaction_space; 358174294Sobrien 359174294Sobrien // Auxiliary functions for scan_and_{forward,adjust_pointers,compact} support. 360174294Sobrien inline size_t adjust_obj_size(size_t size) const { 361174294Sobrien return size; 362174294Sobrien } 363174294Sobrien 364174294Sobrien inline size_t obj_size(const HeapWord* addr) const; 365174294Sobrien 366174294Sobrien template <class SpaceType> 367174294Sobrien static inline void verify_up_to_first_dead(SpaceType* space) NOT_DEBUG_RETURN; 368174294Sobrien 369174294Sobrien template <class SpaceType> 370174294Sobrien static inline void clear_empty_region(SpaceType* space); 371174294Sobrien 372174294Sobrienpublic: 373174294Sobrien CompactibleSpace() : 374174294Sobrien _compaction_top(NULL), _next_compaction_space(NULL) {} 375174294Sobrien 376174294Sobrien virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space); 377174294Sobrien virtual void clear(bool mangle_space); 378174294Sobrien 379174294Sobrien // Used temporarily during a compaction phase to hold the value 380174294Sobrien // top should have when compaction is complete. 381174294Sobrien HeapWord* compaction_top() const { return _compaction_top; } 382174294Sobrien 383174294Sobrien void set_compaction_top(HeapWord* value) { 384174294Sobrien assert(value == NULL || (value >= bottom() && value <= end()), 385174294Sobrien "should point inside space"); 386174294Sobrien _compaction_top = value; 387174294Sobrien } 388174294Sobrien 389174294Sobrien // Perform operations on the space needed after a compaction 390174294Sobrien // has been performed. 391174294Sobrien virtual void reset_after_compaction() = 0; 392174294Sobrien 393174294Sobrien // Returns the next space (in the current generation) to be compacted in 394174294Sobrien // the global compaction order. Also is used to select the next 395174294Sobrien // space into which to compact. 396174294Sobrien 397174294Sobrien virtual CompactibleSpace* next_compaction_space() const { 398174294Sobrien return _next_compaction_space; 399174294Sobrien } 400174294Sobrien 401174294Sobrien void set_next_compaction_space(CompactibleSpace* csp) { 402174294Sobrien _next_compaction_space = csp; 403174294Sobrien } 404174294Sobrien 405174294Sobrien // MarkSweep support phase2 406174294Sobrien 407174294Sobrien // Start the process of compaction of the current space: compute 408174294Sobrien // post-compaction addresses, and insert forwarding pointers. The fields 409174294Sobrien // "cp->gen" and "cp->compaction_space" are the generation and space into 410174294Sobrien // which we are currently compacting. This call updates "cp" as necessary, 411174294Sobrien // and leaves the "compaction_top" of the final value of 412174294Sobrien // "cp->compaction_space" up-to-date. Offset tables may be updated in 413174294Sobrien // this phase as if the final copy had occurred; if so, "cp->threshold" 414174294Sobrien // indicates when the next such action should be taken. 415174294Sobrien virtual void prepare_for_compaction(CompactPoint* cp) = 0; 416174294Sobrien // MarkSweep support phase3 417174294Sobrien virtual void adjust_pointers(); 418174294Sobrien // MarkSweep support phase4 419174294Sobrien virtual void compact(); 420174294Sobrien 421174294Sobrien // The maximum percentage of objects that can be dead in the compacted 422174294Sobrien // live part of a compacted space ("deadwood" support.) 423174294Sobrien virtual size_t allowed_dead_ratio() const { return 0; }; 424174294Sobrien 425174294Sobrien // Some contiguous spaces may maintain some data structures that should 426174294Sobrien // be updated whenever an allocation crosses a boundary. This function 427174294Sobrien // returns the first such boundary. 428174294Sobrien // (The default implementation returns the end of the space, so the 429174294Sobrien // boundary is never crossed.) 430174294Sobrien virtual HeapWord* initialize_threshold() { return end(); } 431174294Sobrien 432174294Sobrien // "q" is an object of the given "size" that should be forwarded; 433174294Sobrien // "cp" names the generation ("gen") and containing "this" (which must 434174294Sobrien // also equal "cp->space"). "compact_top" is where in "this" the 435174294Sobrien // next object should be forwarded to. If there is room in "this" for 436174294Sobrien // the object, insert an appropriate forwarding pointer in "q". 437174294Sobrien // If not, go to the next compaction space (there must 438174294Sobrien // be one, since compaction must succeed -- we go to the first space of 439174294Sobrien // the previous generation if necessary, updating "cp"), reset compact_top 440174294Sobrien // and then forward. In either case, returns the new value of "compact_top". 441174294Sobrien // If the forwarding crosses "cp->threshold", invokes the "cross_threshold" 442174294Sobrien // function of the then-current compaction space, and updates "cp->threshold 443174294Sobrien // accordingly". 444174294Sobrien virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp, 445174294Sobrien HeapWord* compact_top); 446174294Sobrien 447174294Sobrien // Return a size with adjustments as required of the space. 448174294Sobrien virtual size_t adjust_object_size_v(size_t size) const { return size; } 449174294Sobrien 450174294Sobrienprotected: 451174294Sobrien // Used during compaction. 452174294Sobrien HeapWord* _first_dead; 453174294Sobrien HeapWord* _end_of_live; 454174294Sobrien 455174294Sobrien // Minimum size of a free block. 456174294Sobrien virtual size_t minimum_free_block_size() const { return 0; } 457174294Sobrien 458174294Sobrien // This the function is invoked when an allocation of an object covering 459174294Sobrien // "start" to "end occurs crosses the threshold; returns the next 460174294Sobrien // threshold. (The default implementation does nothing.) 461174294Sobrien virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* the_end) { 462174294Sobrien return end(); 463174294Sobrien } 464174294Sobrien 465174294Sobrien // Below are template functions for scan_and_* algorithms (avoiding virtual calls). 466174294Sobrien // The space argument should be a subclass of CompactibleSpace, implementing 467174294Sobrien // scan_limit(), scanned_block_is_obj(), and scanned_block_size(), 468174294Sobrien // and possibly also overriding obj_size(), and adjust_obj_size(). 469174294Sobrien // These functions should avoid virtual calls whenever possible. 470174294Sobrien 471174294Sobrien // Frequently calls adjust_obj_size(). 472174294Sobrien template <class SpaceType> 473174294Sobrien static inline void scan_and_adjust_pointers(SpaceType* space); 474174294Sobrien 475174294Sobrien // Frequently calls obj_size(). 476174294Sobrien template <class SpaceType> 477174294Sobrien static inline void scan_and_compact(SpaceType* space); 478174294Sobrien 479174294Sobrien // Frequently calls scanned_block_is_obj() and scanned_block_size(). 480174294Sobrien // Requires the scan_limit() function. 481174294Sobrien template <class SpaceType> 482174294Sobrien static inline void scan_and_forward(SpaceType* space, CompactPoint* cp); 483174294Sobrien}; 484174294Sobrien 485174294Sobrienclass GenSpaceMangler; 486174294Sobrien 487174294Sobrien// A space in which the free area is contiguous. It therefore supports 488174294Sobrien// faster allocation, and compaction. 489174294Sobrienclass ContiguousSpace: public CompactibleSpace { 490174294Sobrien friend class VMStructs; 491174294Sobrien // Allow scan_and_forward function to call (private) overrides for auxiliary functions on this class 492174294Sobrien template <typename SpaceType> 493174294Sobrien friend void CompactibleSpace::scan_and_forward(SpaceType* space, CompactPoint* cp); 494174294Sobrien 495174294Sobrien private: 496174294Sobrien // Auxiliary functions for scan_and_forward support. 497174294Sobrien // See comments for CompactibleSpace for more information. 498174294Sobrien inline HeapWord* scan_limit() const { 499174294Sobrien return top(); 500174294Sobrien } 501174294Sobrien 502174294Sobrien inline bool scanned_block_is_obj(const HeapWord* addr) const { 503174294Sobrien return true; // Always true, since scan_limit is top 504174294Sobrien } 505174294Sobrien 506174294Sobrien inline size_t scanned_block_size(const HeapWord* addr) const; 507174294Sobrien 508174294Sobrien protected: 509174294Sobrien HeapWord* _top; 510174294Sobrien HeapWord* _concurrent_iteration_safe_limit; 511174294Sobrien // A helper for mangling the unused area of the space in debug builds. 512174294Sobrien GenSpaceMangler* _mangler; 513174294Sobrien 514174294Sobrien GenSpaceMangler* mangler() { return _mangler; } 515174294Sobrien 516174294Sobrien // Allocation helpers (return NULL if full). 517174294Sobrien inline HeapWord* allocate_impl(size_t word_size); 518174294Sobrien inline HeapWord* par_allocate_impl(size_t word_size); 519174294Sobrien 520174294Sobrien public: 521174294Sobrien ContiguousSpace(); 522174294Sobrien ~ContiguousSpace(); 523174294Sobrien 524174294Sobrien virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space); 525174294Sobrien virtual void clear(bool mangle_space); 526174294Sobrien 527174294Sobrien // Accessors 528174294Sobrien HeapWord* top() const { return _top; } 529174294Sobrien void set_top(HeapWord* value) { _top = value; } 530174294Sobrien 531174294Sobrien void set_saved_mark() { _saved_mark_word = top(); } 532174294Sobrien void reset_saved_mark() { _saved_mark_word = bottom(); } 533174294Sobrien 534174294Sobrien bool saved_mark_at_top() const { return saved_mark_word() == top(); } 535174294Sobrien 536174294Sobrien // In debug mode mangle (write it with a particular bit 537174294Sobrien // pattern) the unused part of a space. 538174294Sobrien 539174294Sobrien // Used to save the an address in a space for later use during mangling. 540174294Sobrien void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN; 541174294Sobrien // Used to save the space's current top for later use during mangling. 542174294Sobrien void set_top_for_allocations() PRODUCT_RETURN; 543174294Sobrien 544174294Sobrien // Mangle regions in the space from the current top up to the 545174294Sobrien // previously mangled part of the space. 546174294Sobrien void mangle_unused_area() PRODUCT_RETURN; 547174294Sobrien // Mangle [top, end) 548174294Sobrien void mangle_unused_area_complete() PRODUCT_RETURN; 549174294Sobrien 550174294Sobrien // Do some sparse checking on the area that should have been mangled. 551174294Sobrien void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN; 552174294Sobrien // Check the complete area that should have been mangled. 553174294Sobrien // This code may be NULL depending on the macro DEBUG_MANGLING. 554174294Sobrien void check_mangled_unused_area_complete() PRODUCT_RETURN; 555174294Sobrien 556174294Sobrien // Size computations: sizes in bytes. 557174294Sobrien size_t capacity() const { return byte_size(bottom(), end()); } 558174294Sobrien size_t used() const { return byte_size(bottom(), top()); } 559174294Sobrien size_t free() const { return byte_size(top(), end()); } 560174294Sobrien 561174294Sobrien virtual bool is_free_block(const HeapWord* p) const; 562174294Sobrien 563174294Sobrien // In a contiguous space we have a more obvious bound on what parts 564174294Sobrien // contain objects. 565174294Sobrien MemRegion used_region() const { return MemRegion(bottom(), top()); } 566174294Sobrien 567174294Sobrien // Allocation (return NULL if full) 568174294Sobrien virtual HeapWord* allocate(size_t word_size); 569174294Sobrien virtual HeapWord* par_allocate(size_t word_size); 570174294Sobrien HeapWord* allocate_aligned(size_t word_size); 571174294Sobrien 572174294Sobrien // Iteration 573174294Sobrien void oop_iterate(ExtendedOopClosure* cl); 574174294Sobrien void object_iterate(ObjectClosure* blk); 575174294Sobrien // For contiguous spaces this method will iterate safely over objects 576174294Sobrien // in the space (i.e., between bottom and top) when at a safepoint. 577174294Sobrien void safe_object_iterate(ObjectClosure* blk); 578174294Sobrien 579174294Sobrien // Iterate over as many initialized objects in the space as possible, 580174294Sobrien // calling "cl.do_object_careful" on each. Return NULL if all objects 581174294Sobrien // in the space (at the start of the iteration) were iterated over. 582174294Sobrien // Return an address indicating the extent of the iteration in the 583174294Sobrien // event that the iteration had to return because of finding an 584174294Sobrien // uninitialized object in the space, or if the closure "cl" 585174294Sobrien // signaled early termination. 586174294Sobrien HeapWord* object_iterate_careful(ObjectClosureCareful* cl); 587174294Sobrien HeapWord* concurrent_iteration_safe_limit() { 588174294Sobrien assert(_concurrent_iteration_safe_limit <= top(), 589174294Sobrien "_concurrent_iteration_safe_limit update missed"); 590174294Sobrien return _concurrent_iteration_safe_limit; 591174294Sobrien } 592174294Sobrien // changes the safe limit, all objects from bottom() to the new 593174294Sobrien // limit should be properly initialized 594174294Sobrien void set_concurrent_iteration_safe_limit(HeapWord* new_limit) { 595174294Sobrien assert(new_limit <= top(), "uninitialized objects in the safe range"); 596174294Sobrien _concurrent_iteration_safe_limit = new_limit; 597174294Sobrien } 598174294Sobrien 599174294Sobrien 600174294Sobrien#if INCLUDE_ALL_GCS 601174294Sobrien // In support of parallel oop_iterate. 602174294Sobrien #define ContigSpace_PAR_OOP_ITERATE_DECL(OopClosureType, nv_suffix) \ 603174294Sobrien void par_oop_iterate(MemRegion mr, OopClosureType* blk); 604174294Sobrien 605174294Sobrien ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DECL) 606174294Sobrien #undef ContigSpace_PAR_OOP_ITERATE_DECL 607174294Sobrien#endif // INCLUDE_ALL_GCS 608174294Sobrien 609174294Sobrien // Compaction support 610174294Sobrien virtual void reset_after_compaction() { 611174294Sobrien assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space"); 612174294Sobrien set_top(compaction_top()); 613174294Sobrien // set new iteration safe limit 614174294Sobrien set_concurrent_iteration_safe_limit(compaction_top()); 615174294Sobrien } 616174294Sobrien 617174294Sobrien // Override. 618174294Sobrien DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl, 619174294Sobrien CardTableModRefBS::PrecisionStyle precision, 620174294Sobrien HeapWord* boundary, 621174294Sobrien bool parallel); 622174294Sobrien 623174294Sobrien // Apply "blk->do_oop" to the addresses of all reference fields in objects 624174294Sobrien // starting with the _saved_mark_word, which was noted during a generation's 625174294Sobrien // save_marks and is required to denote the head of an object. 626174294Sobrien // Fields in objects allocated by applications of the closure 627174294Sobrien // *are* included in the iteration. 628174294Sobrien // Updates _saved_mark_word to point to just after the last object 629174294Sobrien // iterated over. 630174294Sobrien#define ContigSpace_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \ 631174294Sobrien void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk); 632174294Sobrien 633174294Sobrien ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DECL) 634174294Sobrien#undef ContigSpace_OOP_SINCE_SAVE_MARKS_DECL 635174294Sobrien 636174294Sobrien // Same as object_iterate, but starting from "mark", which is required 637174294Sobrien // to denote the start of an object. Objects allocated by 638174294Sobrien // applications of the closure *are* included in the iteration. 639174294Sobrien virtual void object_iterate_from(HeapWord* mark, ObjectClosure* blk); 640174294Sobrien 641174294Sobrien // Very inefficient implementation. 642174294Sobrien virtual HeapWord* block_start_const(const void* p) const; 643174294Sobrien size_t block_size(const HeapWord* p) const; 644174294Sobrien // If a block is in the allocated area, it is an object. 645174294Sobrien bool block_is_obj(const HeapWord* p) const { return p < top(); } 646174294Sobrien 647174294Sobrien // Addresses for inlined allocation 648174294Sobrien HeapWord** top_addr() { return &_top; } 649174294Sobrien HeapWord** end_addr() { return &_end; } 650174294Sobrien 651174294Sobrien // Overrides for more efficient compaction support. 652174294Sobrien void prepare_for_compaction(CompactPoint* cp); 653174294Sobrien 654174294Sobrien virtual void print_on(outputStream* st) const; 655174294Sobrien 656174294Sobrien // Checked dynamic downcasts. 657174294Sobrien virtual ContiguousSpace* toContiguousSpace() { 658174294Sobrien return this; 659174294Sobrien } 660174294Sobrien 661174294Sobrien // Debugging 662174294Sobrien virtual void verify() const; 663174294Sobrien 664174294Sobrien // Used to increase collection frequency. "factor" of 0 means entire 665174294Sobrien // space. 666174294Sobrien void allocate_temporary_filler(int factor); 667174294Sobrien}; 668174294Sobrien 669174294Sobrien 670174294Sobrien// A dirty card to oop closure that does filtering. 671174294Sobrien// It knows how to filter out objects that are outside of the _boundary. 672174294Sobrienclass FilteringDCTOC : public DirtyCardToOopClosure { 673174294Sobrienprotected: 674174294Sobrien // Override. 675174294Sobrien void walk_mem_region(MemRegion mr, 676174294Sobrien HeapWord* bottom, HeapWord* top); 677174294Sobrien 678174294Sobrien // Walk the given memory region, from bottom to top, applying 679174294Sobrien // the given oop closure to (possibly) all objects found. The 680174294Sobrien // given oop closure may or may not be the same as the oop 681174294Sobrien // closure with which this closure was created, as it may 682174294Sobrien // be a filtering closure which makes use of the _boundary. 683174294Sobrien // We offer two signatures, so the FilteringClosure static type is 684174294Sobrien // apparent. 685174294Sobrien virtual void walk_mem_region_with_cl(MemRegion mr, 686174294Sobrien HeapWord* bottom, HeapWord* top, 687174294Sobrien ExtendedOopClosure* cl) = 0; 688174294Sobrien virtual void walk_mem_region_with_cl(MemRegion mr, 689174294Sobrien HeapWord* bottom, HeapWord* top, 690174294Sobrien FilteringClosure* cl) = 0; 691174294Sobrien 692174294Sobrienpublic: 693174294Sobrien FilteringDCTOC(Space* sp, ExtendedOopClosure* cl, 694174294Sobrien CardTableModRefBS::PrecisionStyle precision, 695174294Sobrien HeapWord* boundary) : 696174294Sobrien DirtyCardToOopClosure(sp, cl, precision, boundary) {} 697174294Sobrien}; 698174294Sobrien 699174294Sobrien// A dirty card to oop closure for contiguous spaces 700174294Sobrien// (ContiguousSpace and sub-classes). 701174294Sobrien// It is a FilteringClosure, as defined above, and it knows: 702174294Sobrien// 703174294Sobrien// 1. That the actual top of any area in a memory region 704174294Sobrien// contained by the space is bounded by the end of the contiguous 705174294Sobrien// region of the space. 706174294Sobrien// 2. That the space is really made up of objects and not just 707174294Sobrien// blocks. 708174294Sobrien 709174294Sobrienclass ContiguousSpaceDCTOC : public FilteringDCTOC { 710174294Sobrienprotected: 711174294Sobrien // Overrides. 712174294Sobrien HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj); 713174294Sobrien 714174294Sobrien virtual void walk_mem_region_with_cl(MemRegion mr, 715174294Sobrien HeapWord* bottom, HeapWord* top, 716174294Sobrien ExtendedOopClosure* cl); 717174294Sobrien virtual void walk_mem_region_with_cl(MemRegion mr, 718174294Sobrien HeapWord* bottom, HeapWord* top, 719174294Sobrien FilteringClosure* cl); 720174294Sobrien 721174294Sobrienpublic: 722174294Sobrien ContiguousSpaceDCTOC(ContiguousSpace* sp, ExtendedOopClosure* cl, 723174294Sobrien CardTableModRefBS::PrecisionStyle precision, 724174294Sobrien HeapWord* boundary) : 725174294Sobrien FilteringDCTOC(sp, cl, precision, boundary) 726174294Sobrien {} 727174294Sobrien}; 728174294Sobrien 729174294Sobrien// A ContigSpace that Supports an efficient "block_start" operation via 730174294Sobrien// a BlockOffsetArray (whose BlockOffsetSharedArray may be shared with 731174294Sobrien// other spaces.) This is the abstract base class for old generation 732174294Sobrien// (tenured) spaces. 733174294Sobrien 734174294Sobrienclass OffsetTableContigSpace: public ContiguousSpace { 735174294Sobrien friend class VMStructs; 736174294Sobrien protected: 737174294Sobrien BlockOffsetArrayContigSpace _offsets; 738174294Sobrien Mutex _par_alloc_lock; 739174294Sobrien 740174294Sobrien public: 741174294Sobrien // Constructor 742174294Sobrien OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, 743174294Sobrien MemRegion mr); 744174294Sobrien 745174294Sobrien void set_bottom(HeapWord* value); 746174294Sobrien void set_end(HeapWord* value); 747174294Sobrien 748174294Sobrien void clear(bool mangle_space); 749174294Sobrien 750174294Sobrien inline HeapWord* block_start_const(const void* p) const; 751174294Sobrien 752174294Sobrien // Add offset table update. 753174294Sobrien virtual inline HeapWord* allocate(size_t word_size); 754174294Sobrien inline HeapWord* par_allocate(size_t word_size); 755174294Sobrien 756174294Sobrien // MarkSweep support phase3 757174294Sobrien virtual HeapWord* initialize_threshold(); 758174294Sobrien virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end); 759174294Sobrien 760174294Sobrien virtual void print_on(outputStream* st) const; 761174294Sobrien 762174294Sobrien // Debugging 763174294Sobrien void verify() const; 764174294Sobrien}; 765174294Sobrien 766174294Sobrien 767174294Sobrien// Class TenuredSpace is used by TenuredGeneration 768174294Sobrien 769174294Sobrienclass TenuredSpace: public OffsetTableContigSpace { 770174294Sobrien friend class VMStructs; 771174294Sobrien protected: 772174294Sobrien // Mark sweep support 773174294Sobrien size_t allowed_dead_ratio() const; 774174294Sobrien public: 775174294Sobrien // Constructor 776174294Sobrien TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray, 777174294Sobrien MemRegion mr) : 778174294Sobrien OffsetTableContigSpace(sharedOffsetArray, mr) {} 779174294Sobrien}; 780174294Sobrien#endif // SHARE_VM_GC_SHARED_SPACE_HPP 781174294Sobrien