jdk8-mips64-public/hotspot: src/share/vm/memory/space.hpp@86e6d691f2e1 (annotated)

src/share/vm/memory/space.hpp@86e6d691f2e1 (annotated)

src/share/vm/memory/space.hpp

Sat, 23 Nov 2013 12:25:13 +0100

author: mgronlun
date: Sat, 23 Nov 2013 12:25:13 +0100
changeset 6131: 86e6d691f2e1
parent 5119: 12f651e29f6b
child 6198: 55fb97c4c58d
child 6461: bdd155477289
permissions: -rw-r--r--

8028128: Add a type safe alternative for working with counter based data
Reviewed-by: dholmes, egahlin

 /*
  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #ifndef SHARE_VM_MEMORY_SPACE_HPP
 #define SHARE_VM_MEMORY_SPACE_HPP
 #include "memory/allocation.hpp"
 #include "memory/blockOffsetTable.hpp"
 #include "memory/cardTableModRefBS.hpp"
 #include "memory/iterator.hpp"
 #include "memory/memRegion.hpp"
 #include "memory/watermark.hpp"
 #include "oops/markOop.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/prefetch.hpp"
 #include "utilities/macros.hpp"
 #include "utilities/workgroup.hpp"
 #ifdef TARGET_OS_FAMILY_linux
 # include "os_linux.inline.hpp"
 #endif
 #ifdef TARGET_OS_FAMILY_solaris
 # include "os_solaris.inline.hpp"
 #endif
 #ifdef TARGET_OS_FAMILY_windows
 # include "os_windows.inline.hpp"
 #endif
 #ifdef TARGET_OS_FAMILY_bsd
 # include "os_bsd.inline.hpp"
 #endif
 // A space is an abstraction for the "storage units" backing
 // up the generation abstraction. It includes specific
 // implementations for keeping track of free and used space,
 // for iterating over objects and free blocks, etc.
 // Here's the Space hierarchy:
 //
 // - Space               -- an asbtract base class describing a heap area
 //   - CompactibleSpace  -- a space supporting compaction
 //     - CompactibleFreeListSpace -- (used for CMS generation)
 //     - ContiguousSpace -- a compactible space in which all free space
 //                          is contiguous
 //       - EdenSpace     -- contiguous space used as nursery
 //         - ConcEdenSpace -- contiguous space with a 'soft end safe' allocation
 //       - OffsetTableContigSpace -- contiguous space with a block offset array
 //                          that allows "fast" block_start calls
 //         - TenuredSpace -- (used for TenuredGeneration)
 // Forward decls.
 class Space;
 class BlockOffsetArray;
 class BlockOffsetArrayContigSpace;
 class Generation;
 class CompactibleSpace;
 class BlockOffsetTable;
 class GenRemSet;
 class CardTableRS;
 class DirtyCardToOopClosure;
 // An oop closure that is circumscribed by a filtering memory region.
 class SpaceMemRegionOopsIterClosure: public ExtendedOopClosure {
  private:
   ExtendedOopClosure* _cl;
   MemRegion   _mr;
  protected:
   template <class T> void do_oop_work(T* p) {
     if (_mr.contains(p)) {
       _cl->do_oop(p);
     }
   }
  public:
   SpaceMemRegionOopsIterClosure(ExtendedOopClosure* cl, MemRegion mr):
     _cl(cl), _mr(mr) {}
   virtual void do_oop(oop* p);
   virtual void do_oop(narrowOop* p);
   virtual bool do_metadata() {
     // _cl is of type ExtendedOopClosure instead of OopClosure, so that we can check this.
     assert(!_cl->do_metadata(), "I've checked all call paths, this shouldn't happen.");
     return false;
   }
   virtual void do_klass(Klass* k)                         { ShouldNotReachHere(); }
   virtual void do_class_loader_data(ClassLoaderData* cld) { ShouldNotReachHere(); }
 };
 // A Space describes a heap area. Class Space is an abstract
 // base class.
 //
 // Space supports allocation, size computation and GC support is provided.
 //
 // Invariant: bottom() and end() are on page_size boundaries and
 // bottom() <= top() <= end()
 // top() is inclusive and end() is exclusive.
 class Space: public CHeapObj<mtGC> {
   friend class VMStructs;
  protected:
   HeapWord* _bottom;
   HeapWord* _end;
   // Used in support of save_marks()
   HeapWord* _saved_mark_word;
   MemRegionClosure* _preconsumptionDirtyCardClosure;
   // A sequential tasks done structure. This supports
   // parallel GC, where we have threads dynamically
   // claiming sub-tasks from a larger parallel task.
   SequentialSubTasksDone _par_seq_tasks;
   Space():
     _bottom(NULL), _end(NULL), _preconsumptionDirtyCardClosure(NULL) { }
  public:
   // Accessors
   HeapWord* bottom() const         { return _bottom; }
   HeapWord* end() const            { return _end;    }
   virtual void set_bottom(HeapWord* value) { _bottom = value; }
   virtual void set_end(HeapWord* value)    { _end = value; }
   virtual HeapWord* saved_mark_word() const  { return _saved_mark_word; }
   void set_saved_mark_word(HeapWord* p) { _saved_mark_word = p; }
   MemRegionClosure* preconsumptionDirtyCardClosure() const {
     return _preconsumptionDirtyCardClosure;
   }
   void setPreconsumptionDirtyCardClosure(MemRegionClosure* cl) {
     _preconsumptionDirtyCardClosure = cl;
   }
   // Returns a subregion of the space containing all the objects in
   // the space.
   virtual MemRegion used_region() const { return MemRegion(bottom(), end()); }
   // Returns a region that is guaranteed to contain (at least) all objects
   // allocated at the time of the last call to "save_marks".  If the space
   // initializes its DirtyCardToOopClosure's specifying the "contig" option
   // (that is, if the space is contiguous), then this region must contain only
   // such objects: the memregion will be from the bottom of the region to the
   // saved mark.  Otherwise, the "obj_allocated_since_save_marks" method of
   // the space must distiguish between objects in the region allocated before
   // and after the call to save marks.
   virtual MemRegion used_region_at_save_marks() const {
     return MemRegion(bottom(), saved_mark_word());
   }
   // Initialization.
   // "initialize" should be called once on a space, before it is used for
   // any purpose.  The "mr" arguments gives the bounds of the space, and
   // the "clear_space" argument should be true unless the memory in "mr" is
   // known to be zeroed.
   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
   // The "clear" method must be called on a region that may have
   // had allocation performed in it, but is now to be considered empty.
   virtual void clear(bool mangle_space);
   // For detecting GC bugs.  Should only be called at GC boundaries, since
   // some unused space may be used as scratch space during GC's.
   // Default implementation does nothing. We also call this when expanding
   // a space to satisfy an allocation request. See bug #4668531
   virtual void mangle_unused_area() {}
   virtual void mangle_unused_area_complete() {}
   virtual void mangle_region(MemRegion mr) {}
   // Testers
   bool is_empty() const              { return used() == 0; }
   bool not_empty() const             { return used() > 0; }
   // Returns true iff the given the space contains the
   // given address as part of an allocated object. For
   // ceratin kinds of spaces, this might be a potentially
   // expensive operation. To prevent performance problems
   // on account of its inadvertent use in product jvm's,
   // we restrict its use to assertion checks only.
   virtual bool is_in(const void* p) const = 0;
   // Returns true iff the given reserved memory of the space contains the
   // given address.
   bool is_in_reserved(const void* p) const { return _bottom <= p && p < _end; }
   // Returns true iff the given block is not allocated.
   virtual bool is_free_block(const HeapWord* p) const = 0;
   // Test whether p is double-aligned
   static bool is_aligned(void* p) {
     return ((intptr_t)p & (sizeof(double)-1)) == 0;
   }
   // Size computations.  Sizes are in bytes.
   size_t capacity()     const { return byte_size(bottom(), end()); }
   virtual size_t used() const = 0;
   virtual size_t free() const = 0;
   // Iterate over all the ref-containing fields of all objects in the
   // space, calling "cl.do_oop" on each.  Fields in objects allocated by
   // applications of the closure are not included in the iteration.
   virtual void oop_iterate(ExtendedOopClosure* cl);
   // Same as above, restricted to the intersection of a memory region and
   // the space.  Fields in objects allocated by applications of the closure
   // are not included in the iteration.
   virtual void oop_iterate(MemRegion mr, ExtendedOopClosure* cl) = 0;
   // Iterate over all objects in the space, calling "cl.do_object" on
   // each.  Objects allocated by applications of the closure are not
   // included in the iteration.
   virtual void object_iterate(ObjectClosure* blk) = 0;
   // Similar to object_iterate() except only iterates over
   // objects whose internal references point to objects in the space.
   virtual void safe_object_iterate(ObjectClosure* blk) = 0;
   // Iterate over all objects that intersect with mr, calling "cl->do_object"
   // on each.  There is an exception to this: if this closure has already
   // been invoked on an object, it may skip such objects in some cases.  This is
   // Most likely to happen in an "upwards" (ascending address) iteration of
   // MemRegions.
   virtual void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
   // Iterate over as many initialized objects in the space as possible,
   // calling "cl.do_object_careful" on each. Return NULL if all objects
   // in the space (at the start of the iteration) were iterated over.
   // Return an address indicating the extent of the iteration in the
   // event that the iteration had to return because of finding an
   // uninitialized object in the space, or if the closure "cl"
   // signalled early termination.
   virtual HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
   virtual HeapWord* object_iterate_careful_m(MemRegion mr,
                                              ObjectClosureCareful* cl);
   // Create and return a new dirty card to oop closure. Can be
   // overriden to return the appropriate type of closure
   // depending on the type of space in which the closure will
   // operate. ResourceArea allocated.
   virtual DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
                                              CardTableModRefBS::PrecisionStyle precision,
                                              HeapWord* boundary = NULL);
   // If "p" is in the space, returns the address of the start of the
   // "block" that contains "p".  We say "block" instead of "object" since
   // some heaps may not pack objects densely; a chunk may either be an
   // object or a non-object.  If "p" is not in the space, return NULL.
   virtual HeapWord* block_start_const(const void* p) const = 0;
   // The non-const version may have benevolent side effects on the data
   // structure supporting these calls, possibly speeding up future calls.
   // The default implementation, however, is simply to call the const
   // version.
   inline virtual HeapWord* block_start(const void* p);
   // Requires "addr" to be the start of a chunk, and returns its size.
   // "addr + size" is required to be the start of a new chunk, or the end
   // of the active area of the heap.
   virtual size_t block_size(const HeapWord* addr) const = 0;
   // Requires "addr" to be the start of a block, and returns "TRUE" iff
   // the block is an object.
   virtual bool block_is_obj(const HeapWord* addr) const = 0;
   // Requires "addr" to be the start of a block, and returns "TRUE" iff
   // the block is an object and the object is alive.
   virtual bool obj_is_alive(const HeapWord* addr) const;
   // Allocation (return NULL if full).  Assumes the caller has established
   // mutually exclusive access to the space.
   virtual HeapWord* allocate(size_t word_size) = 0;
   // Allocation (return NULL if full).  Enforces mutual exclusion internally.
   virtual HeapWord* par_allocate(size_t word_size) = 0;
   // Returns true if this object has been allocated since a
   // generation's "save_marks" call.
   virtual bool obj_allocated_since_save_marks(const oop obj) const = 0;
   // Mark-sweep-compact support: all spaces can update pointers to objects
   // moving as a part of compaction.
   virtual void adjust_pointers();
   // PrintHeapAtGC support
   virtual void print() const;
   virtual void print_on(outputStream* st) const;
   virtual void print_short() const;
   virtual void print_short_on(outputStream* st) const;
   // Accessor for parallel sequential tasks.
   SequentialSubTasksDone* par_seq_tasks() { return &_par_seq_tasks; }
   // IF "this" is a ContiguousSpace, return it, else return NULL.
   virtual ContiguousSpace* toContiguousSpace() {
     return NULL;
   }
   // Debugging
   virtual void verify() const = 0;
 };
 // A MemRegionClosure (ResourceObj) whose "do_MemRegion" function applies an
 // OopClosure to (the addresses of) all the ref-containing fields that could
 // be modified by virtue of the given MemRegion being dirty. (Note that
 // because of the imprecise nature of the write barrier, this may iterate
 // over oops beyond the region.)
 // This base type for dirty card to oop closures handles memory regions
 // in non-contiguous spaces with no boundaries, and should be sub-classed
 // to support other space types. See ContiguousDCTOC for a sub-class
 // that works with ContiguousSpaces.
 class DirtyCardToOopClosure: public MemRegionClosureRO {
 protected:
   ExtendedOopClosure* _cl;
   Space* _sp;
   CardTableModRefBS::PrecisionStyle _precision;
   HeapWord* _boundary;          // If non-NULL, process only non-NULL oops
                                 // pointing below boundary.
   HeapWord* _min_done;          // ObjHeadPreciseArray precision requires
                                 // a downwards traversal; this is the
                                 // lowest location already done (or,
                                 // alternatively, the lowest address that
                                 // shouldn't be done again.  NULL means infinity.)
   NOT_PRODUCT(HeapWord* _last_bottom;)
   NOT_PRODUCT(HeapWord* _last_explicit_min_done;)
   // Get the actual top of the area on which the closure will
   // operate, given where the top is assumed to be (the end of the
   // memory region passed to do_MemRegion) and where the object
   // at the top is assumed to start. For example, an object may
   // start at the top but actually extend past the assumed top,
   // in which case the top becomes the end of the object.
   virtual HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
   // Walk the given memory region from bottom to (actual) top
   // looking for objects and applying the oop closure (_cl) to
   // them. The base implementation of this treats the area as
   // blocks, where a block may or may not be an object. Sub-
   // classes should override this to provide more accurate
   // or possibly more efficient walking.
   virtual void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top);
 public:
   DirtyCardToOopClosure(Space* sp, ExtendedOopClosure* cl,
                         CardTableModRefBS::PrecisionStyle precision,
                         HeapWord* boundary) :
     _sp(sp), _cl(cl), _precision(precision), _boundary(boundary),
     _min_done(NULL) {
     NOT_PRODUCT(_last_bottom = NULL);
     NOT_PRODUCT(_last_explicit_min_done = NULL);
   }
   void do_MemRegion(MemRegion mr);
   void set_min_done(HeapWord* min_done) {
     _min_done = min_done;
     NOT_PRODUCT(_last_explicit_min_done = _min_done);
   }
 #ifndef PRODUCT
   void set_last_bottom(HeapWord* last_bottom) {
     _last_bottom = last_bottom;
   }
 #endif
 };
 // A structure to represent a point at which objects are being copied
 // during compaction.
 class CompactPoint : public StackObj {
 public:
   Generation* gen;
   CompactibleSpace* space;
   HeapWord* threshold;
   CompactPoint(Generation* _gen, CompactibleSpace* _space,
                HeapWord* _threshold) :
     gen(_gen), space(_space), threshold(_threshold) {}
 };
 // A space that supports compaction operations.  This is usually, but not
 // necessarily, a space that is normally contiguous.  But, for example, a
 // free-list-based space whose normal collection is a mark-sweep without
 // compaction could still support compaction in full GC's.
 class CompactibleSpace: public Space {
   friend class VMStructs;
   friend class CompactibleFreeListSpace;
 private:
   HeapWord* _compaction_top;
   CompactibleSpace* _next_compaction_space;
 public:
   CompactibleSpace() :
    _compaction_top(NULL), _next_compaction_space(NULL) {}
   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
   virtual void clear(bool mangle_space);
   // Used temporarily during a compaction phase to hold the value
   // top should have when compaction is complete.
   HeapWord* compaction_top() const { return _compaction_top;    }
   void set_compaction_top(HeapWord* value) {
     assert(value == NULL || (value >= bottom() && value <= end()),
       "should point inside space");
     _compaction_top = value;
   }
   // Perform operations on the space needed after a compaction
   // has been performed.
   virtual void reset_after_compaction() {}
   // Returns the next space (in the current generation) to be compacted in
   // the global compaction order.  Also is used to select the next
   // space into which to compact.
   virtual CompactibleSpace* next_compaction_space() const {
     return _next_compaction_space;
   }
   void set_next_compaction_space(CompactibleSpace* csp) {
     _next_compaction_space = csp;
   }
   // MarkSweep support phase2
   // Start the process of compaction of the current space: compute
   // post-compaction addresses, and insert forwarding pointers.  The fields
   // "cp->gen" and "cp->compaction_space" are the generation and space into
   // which we are currently compacting.  This call updates "cp" as necessary,
   // and leaves the "compaction_top" of the final value of
   // "cp->compaction_space" up-to-date.  Offset tables may be updated in
   // this phase as if the final copy had occurred; if so, "cp->threshold"
   // indicates when the next such action should be taken.
   virtual void prepare_for_compaction(CompactPoint* cp);
   // MarkSweep support phase3
   virtual void adjust_pointers();
   // MarkSweep support phase4
   virtual void compact();
   // The maximum percentage of objects that can be dead in the compacted
   // live part of a compacted space ("deadwood" support.)
   virtual size_t allowed_dead_ratio() const { return 0; };
   // Some contiguous spaces may maintain some data structures that should
   // be updated whenever an allocation crosses a boundary.  This function
   // returns the first such boundary.
   // (The default implementation returns the end of the space, so the
   // boundary is never crossed.)
   virtual HeapWord* initialize_threshold() { return end(); }
   // "q" is an object of the given "size" that should be forwarded;
   // "cp" names the generation ("gen") and containing "this" (which must
   // also equal "cp->space").  "compact_top" is where in "this" the
   // next object should be forwarded to.  If there is room in "this" for
   // the object, insert an appropriate forwarding pointer in "q".
   // If not, go to the next compaction space (there must
   // be one, since compaction must succeed -- we go to the first space of
   // the previous generation if necessary, updating "cp"), reset compact_top
   // and then forward.  In either case, returns the new value of "compact_top".
   // If the forwarding crosses "cp->threshold", invokes the "cross_threhold"
   // function of the then-current compaction space, and updates "cp->threshold
   // accordingly".
   virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp,
                     HeapWord* compact_top);
   // Return a size with adjusments as required of the space.
   virtual size_t adjust_object_size_v(size_t size) const { return size; }
 protected:
   // Used during compaction.
   HeapWord* _first_dead;
   HeapWord* _end_of_live;
   // Minimum size of a free block.
   virtual size_t minimum_free_block_size() const = 0;
   // This the function is invoked when an allocation of an object covering
   // "start" to "end occurs crosses the threshold; returns the next
   // threshold.  (The default implementation does nothing.)
   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* the_end) {
     return end();
   }
   // Requires "allowed_deadspace_words > 0", that "q" is the start of a
   // free block of the given "word_len", and that "q", were it an object,
   // would not move if forwared.  If the size allows, fill the free
   // block with an object, to prevent excessive compaction.  Returns "true"
   // iff the free region was made deadspace, and modifies
   // "allowed_deadspace_words" to reflect the number of available deadspace
   // words remaining after this operation.
   bool insert_deadspace(size_t& allowed_deadspace_words, HeapWord* q,
                         size_t word_len);
 };
 #define SCAN_AND_FORWARD(cp,scan_limit,block_is_obj,block_size) {            \
   /* Compute the new addresses for the live objects and store it in the mark \
    * Used by universe::mark_sweep_phase2()                                   \
    */                                                                        \
   HeapWord* compact_top; /* This is where we are currently compacting to. */ \
                                                                              \
   /* We're sure to be here before any objects are compacted into this        \
    * space, so this is a good time to initialize this:                       \
    */                                                                        \
   set_compaction_top(bottom());                                              \
                                                                              \
   if (cp->space == NULL) {                                                   \
     assert(cp->gen != NULL, "need a generation");                            \
     assert(cp->threshold == NULL, "just checking");                          \
     assert(cp->gen->first_compaction_space() == this, "just checking");      \
     cp->space = cp->gen->first_compaction_space();                           \
     compact_top = cp->space->bottom();                                       \
     cp->space->set_compaction_top(compact_top);                              \
     cp->threshold = cp->space->initialize_threshold();                       \
   } else {                                                                   \
     compact_top = cp->space->compaction_top();                               \
   }                                                                          \
                                                                              \
   /* We allow some amount of garbage towards the bottom of the space, so     \
    * we don't start compacting before there is a significant gain to be made.\
    * Occasionally, we want to ensure a full compaction, which is determined  \
    * by the MarkSweepAlwaysCompactCount parameter.                           \
    */                                                                        \
   uint invocations = MarkSweep::total_invocations();                         \
   bool skip_dead = ((invocations % MarkSweepAlwaysCompactCount) != 0);       \
                                                                              \
   size_t allowed_deadspace = 0;                                              \
   if (skip_dead) {                                                           \
     const size_t ratio = allowed_dead_ratio();                               \
     allowed_deadspace = (capacity() * ratio / 100) / HeapWordSize;           \
   }                                                                          \
                                                                              \
   HeapWord* q = bottom();                                                    \
   HeapWord* t = scan_limit();                                                \
                                                                              \
   HeapWord*  end_of_live= q;    /* One byte beyond the last byte of the last \
                                    live object. */                           \
   HeapWord*  first_dead = end();/* The first dead object. */                 \
   LiveRange* liveRange  = NULL; /* The current live range, recorded in the   \
                                    first header of preceding free area. */   \
   _first_dead = first_dead;                                                  \
                                                                              \
   const intx interval = PrefetchScanIntervalInBytes;                         \
                                                                              \
   while (q < t) {                                                            \
     assert(!block_is_obj(q) ||                                               \
            oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() ||   \
            oop(q)->mark()->has_bias_pattern(),                               \
            "these are the only valid states during a mark sweep");           \
     if (block_is_obj(q) && oop(q)->is_gc_marked()) {                         \
       /* prefetch beyond q */                                                \
       Prefetch::write(q, interval);                                          \
       size_t size = block_size(q);                                           \
       compact_top = cp->space->forward(oop(q), size, cp, compact_top);       \
       q += size;                                                             \
       end_of_live = q;                                                       \
     } else {                                                                 \
       /* run over all the contiguous dead objects */                         \
       HeapWord* end = q;                                                     \
       do {                                                                   \
         /* prefetch beyond end */                                            \
         Prefetch::write(end, interval);                                      \
         end += block_size(end);                                              \
       } while (end < t && (!block_is_obj(end) || !oop(end)->is_gc_marked()));\
                                                                              \
       /* see if we might want to pretend this object is alive so that        \
        * we don't have to compact quite as often.                            \
        */                                                                    \
       if (allowed_deadspace > 0 && q == compact_top) {                       \
         size_t sz = pointer_delta(end, q);                                   \
         if (insert_deadspace(allowed_deadspace, q, sz)) {                    \
           compact_top = cp->space->forward(oop(q), sz, cp, compact_top);     \
           q = end;                                                           \
           end_of_live = end;                                                 \
           continue;                                                          \
         }                                                                    \
       }                                                                      \
                                                                              \
       /* otherwise, it really is a free region. */                           \
                                                                              \
       /* for the previous LiveRange, record the end of the live objects. */  \
       if (liveRange) {                                                       \
         liveRange->set_end(q);                                               \
       }                                                                      \
                                                                              \
       /* record the current LiveRange object.                                \
        * liveRange->start() is overlaid on the mark word.                    \
        */                                                                    \
       liveRange = (LiveRange*)q;                                             \
       liveRange->set_start(end);                                             \
       liveRange->set_end(end);                                               \
                                                                              \
       /* see if this is the first dead region. */                            \
       if (q < first_dead) {                                                  \
         first_dead = q;                                                      \
       }                                                                      \
                                                                              \
       /* move on to the next object */                                       \
       q = end;                                                               \
     }                                                                        \
   }                                                                          \
                                                                              \
   assert(q == t, "just checking");                                           \
   if (liveRange != NULL) {                                                   \
     liveRange->set_end(q);                                                   \
   }                                                                          \
   _end_of_live = end_of_live;                                                \
   if (end_of_live < first_dead) {                                            \
     first_dead = end_of_live;                                                \
   }                                                                          \
   _first_dead = first_dead;                                                  \
                                                                              \
   /* save the compaction_top of the compaction space. */                     \
   cp->space->set_compaction_top(compact_top);                                \
 }
 #define SCAN_AND_ADJUST_POINTERS(adjust_obj_size) {                             \
   /* adjust all the interior pointers to point at the new locations of objects  \
    * Used by MarkSweep::mark_sweep_phase3() */                                  \
                                                                                 \
   HeapWord* q = bottom();                                                       \
   HeapWord* t = _end_of_live;  /* Established by "prepare_for_compaction". */   \
                                                                                 \
   assert(_first_dead <= _end_of_live, "Stands to reason, no?");                 \
                                                                                 \
   if (q < t && _first_dead > q &&                                               \
       !oop(q)->is_gc_marked()) {                                                \
     /* we have a chunk of the space which hasn't moved and we've                \
      * reinitialized the mark word during the previous pass, so we can't        \
      * use is_gc_marked for the traversal. */                                   \
     HeapWord* end = _first_dead;                                                \
                                                                                 \
     while (q < end) {                                                           \
       /* I originally tried to conjoin "block_start(q) == q" to the             \
        * assertion below, but that doesn't work, because you can't              \
        * accurately traverse previous objects to get to the current one         \
        * after their pointers have been                                         \
        * updated, until the actual compaction is done.  dld, 4/00 */            \
       assert(block_is_obj(q),                                                   \
              "should be at block boundaries, and should be looking at objs");   \
                                                                                 \
       /* point all the oops to the new location */                              \
       size_t size = oop(q)->adjust_pointers();                                  \
       size = adjust_obj_size(size);                                             \
                                                                                 \
       q += size;                                                                \
     }                                                                           \
                                                                                 \
     if (_first_dead == t) {                                                     \
       q = t;                                                                    \
     } else {                                                                    \
       /* $$$ This is funky.  Using this to read the previously written          \
        * LiveRange.  See also use below. */                                     \
       q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer();                \
     }                                                                           \
   }                                                                             \
                                                                                 \
   const intx interval = PrefetchScanIntervalInBytes;                            \
                                                                                 \
   debug_only(HeapWord* prev_q = NULL);                                          \
   while (q < t) {                                                               \
     /* prefetch beyond q */                                                     \
     Prefetch::write(q, interval);                                               \
     if (oop(q)->is_gc_marked()) {                                               \
       /* q is alive */                                                          \
       /* point all the oops to the new location */                              \
       size_t size = oop(q)->adjust_pointers();                                  \
       size = adjust_obj_size(size);                                             \
       debug_only(prev_q = q);                                                   \
       q += size;                                                                \
     } else {                                                                    \
       /* q is not a live object, so its mark should point at the next           \
        * live object */                                                         \
       debug_only(prev_q = q);                                                   \
       q = (HeapWord*) oop(q)->mark()->decode_pointer();                         \
       assert(q > prev_q, "we should be moving forward through memory");         \
     }                                                                           \
   }                                                                             \
                                                                                 \
   assert(q == t, "just checking");                                              \
 }
 #define SCAN_AND_COMPACT(obj_size) {                                            \
   /* Copy all live objects to their new location                                \
    * Used by MarkSweep::mark_sweep_phase4() */                                  \
                                                                                 \
   HeapWord*       q = bottom();                                                 \
   HeapWord* const t = _end_of_live;                                             \
   debug_only(HeapWord* prev_q = NULL);                                          \
                                                                                 \
   if (q < t && _first_dead > q &&                                               \
       !oop(q)->is_gc_marked()) {                                                \
     debug_only(                                                                 \
     /* we have a chunk of the space which hasn't moved and we've reinitialized  \
      * the mark word during the previous pass, so we can't use is_gc_marked for \
      * the traversal. */                                                        \
     HeapWord* const end = _first_dead;                                          \
                                                                                 \
     while (q < end) {                                                           \
       size_t size = obj_size(q);                                                \
       assert(!oop(q)->is_gc_marked(),                                           \
              "should be unmarked (special dense prefix handling)");             \
       debug_only(prev_q = q);                                                   \
       q += size;                                                                \
     }                                                                           \
     )  /* debug_only */                                                         \
                                                                                 \
     if (_first_dead == t) {                                                     \
       q = t;                                                                    \
     } else {                                                                    \
       /* $$$ Funky */                                                           \
       q = (HeapWord*) oop(_first_dead)->mark()->decode_pointer();               \
     }                                                                           \
   }                                                                             \
                                                                                 \
   const intx scan_interval = PrefetchScanIntervalInBytes;                       \
   const intx copy_interval = PrefetchCopyIntervalInBytes;                       \
   while (q < t) {                                                               \
     if (!oop(q)->is_gc_marked()) {                                              \
       /* mark is pointer to next marked oop */                                  \
       debug_only(prev_q = q);                                                   \
       q = (HeapWord*) oop(q)->mark()->decode_pointer();                         \
       assert(q > prev_q, "we should be moving forward through memory");         \
     } else {                                                                    \
       /* prefetch beyond q */                                                   \
       Prefetch::read(q, scan_interval);                                         \
                                                                                 \
       /* size and destination */                                                \
       size_t size = obj_size(q);                                                \
       HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee();                \
                                                                                 \
       /* prefetch beyond compaction_top */                                      \
       Prefetch::write(compaction_top, copy_interval);                           \
                                                                                 \
       /* copy object and reinit its mark */                                     \
       assert(q != compaction_top, "everything in this pass should be moving");  \
       Copy::aligned_conjoint_words(q, compaction_top, size);                    \
       oop(compaction_top)->init_mark();                                         \
       assert(oop(compaction_top)->klass() != NULL, "should have a class");      \
                                                                                 \
       debug_only(prev_q = q);                                                   \
       q += size;                                                                \
     }                                                                           \
   }                                                                             \
                                                                                 \
   /* Let's remember if we were empty before we did the compaction. */           \
   bool was_empty = used_region().is_empty();                                    \
   /* Reset space after compaction is complete */                                \
   reset_after_compaction();                                                     \
   /* We do this clear, below, since it has overloaded meanings for some */      \
   /* space subtypes.  For example, OffsetTableContigSpace's that were   */      \
   /* compacted into will have had their offset table thresholds updated */      \
   /* continuously, but those that weren't need to have their thresholds */      \
   /* re-initialized.  Also mangles unused area for debugging.           */      \
   if (used_region().is_empty()) {                                               \
     if (!was_empty) clear(SpaceDecorator::Mangle);                              \
   } else {                                                                      \
     if (ZapUnusedHeapArea) mangle_unused_area();                                \
   }                                                                             \
 }
 class GenSpaceMangler;
 // A space in which the free area is contiguous.  It therefore supports
 // faster allocation, and compaction.
 class ContiguousSpace: public CompactibleSpace {
   friend class OneContigSpaceCardGeneration;
   friend class VMStructs;
  protected:
   HeapWord* _top;
   HeapWord* _concurrent_iteration_safe_limit;
   // A helper for mangling the unused area of the space in debug builds.
   GenSpaceMangler* _mangler;
   GenSpaceMangler* mangler() { return _mangler; }
   // Allocation helpers (return NULL if full).
   inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
   inline HeapWord* par_allocate_impl(size_t word_size, HeapWord* end_value);
  public:
   ContiguousSpace();
   ~ContiguousSpace();
   virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
   virtual void clear(bool mangle_space);
   // Accessors
   HeapWord* top() const            { return _top;    }
   void set_top(HeapWord* value)    { _top = value; }
   virtual void set_saved_mark()    { _saved_mark_word = top();    }
   void reset_saved_mark()          { _saved_mark_word = bottom(); }
   WaterMark bottom_mark()     { return WaterMark(this, bottom()); }
   WaterMark top_mark()        { return WaterMark(this, top()); }
   WaterMark saved_mark()      { return WaterMark(this, saved_mark_word()); }
   bool saved_mark_at_top() const { return saved_mark_word() == top(); }
   // In debug mode mangle (write it with a particular bit
   // pattern) the unused part of a space.
   // Used to save the an address in a space for later use during mangling.
   void set_top_for_allocations(HeapWord* v) PRODUCT_RETURN;
   // Used to save the space's current top for later use during mangling.
   void set_top_for_allocations() PRODUCT_RETURN;
   // Mangle regions in the space from the current top up to the
   // previously mangled part of the space.
   void mangle_unused_area() PRODUCT_RETURN;
   // Mangle [top, end)
   void mangle_unused_area_complete() PRODUCT_RETURN;
   // Mangle the given MemRegion.
   void mangle_region(MemRegion mr) PRODUCT_RETURN;
   // Do some sparse checking on the area that should have been mangled.
   void check_mangled_unused_area(HeapWord* limit) PRODUCT_RETURN;
   // Check the complete area that should have been mangled.
   // This code may be NULL depending on the macro DEBUG_MANGLING.
   void check_mangled_unused_area_complete() PRODUCT_RETURN;
   // Size computations: sizes in bytes.
   size_t capacity() const        { return byte_size(bottom(), end()); }
   size_t used() const            { return byte_size(bottom(), top()); }
   size_t free() const            { return byte_size(top(),    end()); }
   // Override from space.
   bool is_in(const void* p) const;
   virtual bool is_free_block(const HeapWord* p) const;
   // In a contiguous space we have a more obvious bound on what parts
   // contain objects.
   MemRegion used_region() const { return MemRegion(bottom(), top()); }
   MemRegion used_region_at_save_marks() const {
     return MemRegion(bottom(), saved_mark_word());
   }
   // Allocation (return NULL if full)
   virtual HeapWord* allocate(size_t word_size);
   virtual HeapWord* par_allocate(size_t word_size);
   virtual bool obj_allocated_since_save_marks(const oop obj) const {
     return (HeapWord*)obj >= saved_mark_word();
   }
   // Iteration
   void oop_iterate(ExtendedOopClosure* cl);
   void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
   void object_iterate(ObjectClosure* blk);
   // For contiguous spaces this method will iterate safely over objects
   // in the space (i.e., between bottom and top) when at a safepoint.
   void safe_object_iterate(ObjectClosure* blk);
   void object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl);
   // iterates on objects up to the safe limit
   HeapWord* object_iterate_careful(ObjectClosureCareful* cl);
   HeapWord* concurrent_iteration_safe_limit() {
     assert(_concurrent_iteration_safe_limit <= top(),
            "_concurrent_iteration_safe_limit update missed");
     return _concurrent_iteration_safe_limit;
   }
   // changes the safe limit, all objects from bottom() to the new
   // limit should be properly initialized
   void set_concurrent_iteration_safe_limit(HeapWord* new_limit) {
     assert(new_limit <= top(), "uninitialized objects in the safe range");
     _concurrent_iteration_safe_limit = new_limit;
   }
 #if INCLUDE_ALL_GCS
   // In support of parallel oop_iterate.
   #define ContigSpace_PAR_OOP_ITERATE_DECL(OopClosureType, nv_suffix)  \
     void par_oop_iterate(MemRegion mr, OopClosureType* blk);
     ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DECL)
   #undef ContigSpace_PAR_OOP_ITERATE_DECL
 #endif // INCLUDE_ALL_GCS
   // Compaction support
   virtual void reset_after_compaction() {
     assert(compaction_top() >= bottom() && compaction_top() <= end(), "should point inside space");
     set_top(compaction_top());
     // set new iteration safe limit
     set_concurrent_iteration_safe_limit(compaction_top());
   }
   virtual size_t minimum_free_block_size() const { return 0; }
   // Override.
   DirtyCardToOopClosure* new_dcto_cl(ExtendedOopClosure* cl,
                                      CardTableModRefBS::PrecisionStyle precision,
                                      HeapWord* boundary = NULL);
   // Apply "blk->do_oop" to the addresses of all reference fields in objects
   // starting with the _saved_mark_word, which was noted during a generation's
   // save_marks and is required to denote the head of an object.
   // Fields in objects allocated by applications of the closure
   // *are* included in the iteration.
   // Updates _saved_mark_word to point to just after the last object
   // iterated over.
 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix)  \
   void oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk);
   ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DECL)
 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DECL
   // Same as object_iterate, but starting from "mark", which is required
   // to denote the start of an object.  Objects allocated by
   // applications of the closure *are* included in the iteration.
   virtual void object_iterate_from(WaterMark mark, ObjectClosure* blk);
   // Very inefficient implementation.
   virtual HeapWord* block_start_const(const void* p) const;
   size_t block_size(const HeapWord* p) const;
   // If a block is in the allocated area, it is an object.
   bool block_is_obj(const HeapWord* p) const { return p < top(); }
   // Addresses for inlined allocation
   HeapWord** top_addr() { return &_top; }
   HeapWord** end_addr() { return &_end; }
   // Overrides for more efficient compaction support.
   void prepare_for_compaction(CompactPoint* cp);
   // PrintHeapAtGC support.
   virtual void print_on(outputStream* st) const;
   // Checked dynamic downcasts.
   virtual ContiguousSpace* toContiguousSpace() {
     return this;
   }
   // Debugging
   virtual void verify() const;
   // Used to increase collection frequency.  "factor" of 0 means entire
   // space.
   void allocate_temporary_filler(int factor);
 };
 // A dirty card to oop closure that does filtering.
 // It knows how to filter out objects that are outside of the _boundary.
 class Filtering_DCTOC : public DirtyCardToOopClosure {
 protected:
   // Override.
   void walk_mem_region(MemRegion mr,
                        HeapWord* bottom, HeapWord* top);
   // Walk the given memory region, from bottom to top, applying
   // the given oop closure to (possibly) all objects found. The
   // given oop closure may or may not be the same as the oop
   // closure with which this closure was created, as it may
   // be a filtering closure which makes use of the _boundary.
   // We offer two signatures, so the FilteringClosure static type is
   // apparent.
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        ExtendedOopClosure* cl) = 0;
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        FilteringClosure* cl) = 0;
 public:
   Filtering_DCTOC(Space* sp, ExtendedOopClosure* cl,
                   CardTableModRefBS::PrecisionStyle precision,
                   HeapWord* boundary) :
     DirtyCardToOopClosure(sp, cl, precision, boundary) {}
 };
 // A dirty card to oop closure for contiguous spaces
 // (ContiguousSpace and sub-classes).
 // It is a FilteringClosure, as defined above, and it knows:
 //
 // 1. That the actual top of any area in a memory region
 //    contained by the space is bounded by the end of the contiguous
 //    region of the space.
 // 2. That the space is really made up of objects and not just
 //    blocks.
 class ContiguousSpaceDCTOC : public Filtering_DCTOC {
 protected:
   // Overrides.
   HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj);
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        ExtendedOopClosure* cl);
   virtual void walk_mem_region_with_cl(MemRegion mr,
                                        HeapWord* bottom, HeapWord* top,
                                        FilteringClosure* cl);
 public:
   ContiguousSpaceDCTOC(ContiguousSpace* sp, ExtendedOopClosure* cl,
                        CardTableModRefBS::PrecisionStyle precision,
                        HeapWord* boundary) :
     Filtering_DCTOC(sp, cl, precision, boundary)
   {}
 };
 // Class EdenSpace describes eden-space in new generation.
 class DefNewGeneration;
 class EdenSpace : public ContiguousSpace {
   friend class VMStructs;
  private:
   DefNewGeneration* _gen;
   // _soft_end is used as a soft limit on allocation.  As soft limits are
   // reached, the slow-path allocation code can invoke other actions and then
   // adjust _soft_end up to a new soft limit or to end().
   HeapWord* _soft_end;
  public:
   EdenSpace(DefNewGeneration* gen) :
    _gen(gen), _soft_end(NULL) {}
   // Get/set just the 'soft' limit.
   HeapWord* soft_end()               { return _soft_end; }
   HeapWord** soft_end_addr()         { return &_soft_end; }
   void set_soft_end(HeapWord* value) { _soft_end = value; }
   // Override.
   void clear(bool mangle_space);
   // Set both the 'hard' and 'soft' limits (_end and _soft_end).
   void set_end(HeapWord* value) {
     set_soft_end(value);
     ContiguousSpace::set_end(value);
   }
   // Allocation (return NULL if full)
   HeapWord* allocate(size_t word_size);
   HeapWord* par_allocate(size_t word_size);
 };
 // Class ConcEdenSpace extends EdenSpace for the sake of safe
 // allocation while soft-end is being modified concurrently
 class ConcEdenSpace : public EdenSpace {
  public:
   ConcEdenSpace(DefNewGeneration* gen) : EdenSpace(gen) { }
   // Allocation (return NULL if full)
   HeapWord* par_allocate(size_t word_size);
 };
 // A ContigSpace that Supports an efficient "block_start" operation via
 // a BlockOffsetArray (whose BlockOffsetSharedArray may be shared with
 // other spaces.)  This is the abstract base class for old generation
 // (tenured) spaces.
 class OffsetTableContigSpace: public ContiguousSpace {
   friend class VMStructs;
  protected:
   BlockOffsetArrayContigSpace _offsets;
   Mutex _par_alloc_lock;
  public:
   // Constructor
   OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
                          MemRegion mr);
   void set_bottom(HeapWord* value);
   void set_end(HeapWord* value);
   void clear(bool mangle_space);
   inline HeapWord* block_start_const(const void* p) const;
   // Add offset table update.
   virtual inline HeapWord* allocate(size_t word_size);
   inline HeapWord* par_allocate(size_t word_size);
   // MarkSweep support phase3
   virtual HeapWord* initialize_threshold();
   virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
   virtual void print_on(outputStream* st) const;
   // Debugging
   void verify() const;
 };
 // Class TenuredSpace is used by TenuredGeneration
 class TenuredSpace: public OffsetTableContigSpace {
   friend class VMStructs;
  protected:
   // Mark sweep support
   size_t allowed_dead_ratio() const;
  public:
   // Constructor
   TenuredSpace(BlockOffsetSharedArray* sharedOffsetArray,
                MemRegion mr) :
     OffsetTableContigSpace(sharedOffsetArray, mr) {}
 };
 #endif // SHARE_VM_MEMORY_SPACE_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/space.hpp@86e6d691f2e1 (annotated)

src/share/vm/memory/space.hpp