jdk8-mips64-public/hotspot: src/share/vm/memory/space.cpp@d06a2d7fcd5b (annotated)

src/share/vm/memory/space.cpp@d06a2d7fcd5b (annotated)

src/share/vm/memory/space.cpp

Mon, 21 Nov 2011 07:47:34 +0100

author: brutisso
date: Mon, 21 Nov 2011 07:47:34 +0100
changeset 3290: d06a2d7fcd5b
parent 2889: fc2b798ab316
child 3335: 3c648b9ad052
permissions: -rw-r--r--

7110718: -XX:MarkSweepAlwaysCompactCount=0 crashes the JVM
Summary: Interpret MarkSweepAlwaysCompactCount < 1 as never do full compaction
Reviewed-by: ysr, tonyp, jmasa, johnc

 /*
  * Copyright (c) 1997, 2010, 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.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "gc_implementation/shared/liveRange.hpp"
 #include "gc_implementation/shared/markSweep.hpp"
 #include "gc_implementation/shared/spaceDecorator.hpp"
 #include "memory/blockOffsetTable.inline.hpp"
 #include "memory/defNewGeneration.hpp"
 #include "memory/genCollectedHeap.hpp"
 #include "memory/space.hpp"
 #include "memory/space.inline.hpp"
 #include "memory/universe.inline.hpp"
 #include "oops/oop.inline.hpp"
 #include "oops/oop.inline2.hpp"
 #include "runtime/java.hpp"
 #include "runtime/safepoint.hpp"
 #include "utilities/copy.hpp"
 #include "utilities/globalDefinitions.hpp"
 void SpaceMemRegionOopsIterClosure::do_oop(oop* p)       { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
 void SpaceMemRegionOopsIterClosure::do_oop(narrowOop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
                                                 HeapWord* top_obj) {
   if (top_obj != NULL) {
     if (_sp->block_is_obj(top_obj)) {
       if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
         if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
           // An arrayOop is starting on the dirty card - since we do exact
           // store checks for objArrays we are done.
         } else {
           // Otherwise, it is possible that the object starting on the dirty
           // card spans the entire card, and that the store happened on a
           // later card.  Figure out where the object ends.
           // Use the block_size() method of the space over which
           // the iteration is being done.  That space (e.g. CMS) may have
           // specific requirements on object sizes which will
           // be reflected in the block_size() method.
           top = top_obj + oop(top_obj)->size();
         }
       }
     } else {
       top = top_obj;
     }
   } else {
     assert(top == _sp->end(), "only case where top_obj == NULL");
   }
   return top;
 }
 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
                                             HeapWord* bottom,
                                             HeapWord* top) {
   // 1. Blocks may or may not be objects.
   // 2. Even when a block_is_obj(), it may not entirely
   //    occupy the block if the block quantum is larger than
   //    the object size.
   // We can and should try to optimize by calling the non-MemRegion
   // version of oop_iterate() for all but the extremal objects
   // (for which we need to call the MemRegion version of
   // oop_iterate()) To be done post-beta XXX
   for (; bottom < top; bottom += _sp->block_size(bottom)) {
     // As in the case of contiguous space above, we'd like to
     // just use the value returned by oop_iterate to increment the
     // current pointer; unfortunately, that won't work in CMS because
     // we'd need an interface change (it seems) to have the space
     // "adjust the object size" (for instance pad it up to its
     // block alignment or minimum block size restrictions. XXX
     if (_sp->block_is_obj(bottom) &&
         !_sp->obj_allocated_since_save_marks(oop(bottom))) {
       oop(bottom)->oop_iterate(_cl, mr);
     }
   }
 }
 // We get called with "mr" representing the dirty region
 // that we want to process. Because of imprecise marking,
 // we may need to extend the incoming "mr" to the right,
 // and scan more. However, because we may already have
 // scanned some of that extended region, we may need to
 // trim its right-end back some so we do not scan what
 // we (or another worker thread) may already have scanned
 // or planning to scan.
 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
   // Some collectors need to do special things whenever their dirty
   // cards are processed. For instance, CMS must remember mutator updates
   // (i.e. dirty cards) so as to re-scan mutated objects.
   // Such work can be piggy-backed here on dirty card scanning, so as to make
   // it slightly more efficient than doing a complete non-detructive pre-scan
   // of the card table.
   MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
   if (pCl != NULL) {
     pCl->do_MemRegion(mr);
   }
   HeapWord* bottom = mr.start();
   HeapWord* last = mr.last();
   HeapWord* top = mr.end();
   HeapWord* bottom_obj;
   HeapWord* top_obj;
   assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
          _precision == CardTableModRefBS::Precise,
          "Only ones we deal with for now.");
   assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
          _cl->idempotent() || _last_bottom == NULL ||
          top <= _last_bottom,
          "Not decreasing");
   NOT_PRODUCT(_last_bottom = mr.start());
   bottom_obj = _sp->block_start(bottom);
   top_obj    = _sp->block_start(last);
   assert(bottom_obj <= bottom, "just checking");
   assert(top_obj    <= top,    "just checking");
   // Given what we think is the top of the memory region and
   // the start of the object at the top, get the actual
   // value of the top.
   top = get_actual_top(top, top_obj);
   // If the previous call did some part of this region, don't redo.
   if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
       _min_done != NULL &&
       _min_done < top) {
     top = _min_done;
   }
   // Top may have been reset, and in fact may be below bottom,
   // e.g. the dirty card region is entirely in a now free object
   // -- something that could happen with a concurrent sweeper.
   bottom = MIN2(bottom, top);
   MemRegion extended_mr = MemRegion(bottom, top);
   assert(bottom <= top &&
          (_precision != CardTableModRefBS::ObjHeadPreciseArray ||
           _min_done == NULL ||
           top <= _min_done),
          "overlap!");
   // Walk the region if it is not empty; otherwise there is nothing to do.
   if (!extended_mr.is_empty()) {
     walk_mem_region(extended_mr, bottom_obj, top);
   }
   // An idempotent closure might be applied in any order, so we don't
   // record a _min_done for it.
   if (!_cl->idempotent()) {
     _min_done = bottom;
   } else {
     assert(_min_done == _last_explicit_min_done,
            "Don't update _min_done for idempotent cl");
   }
 }
 DirtyCardToOopClosure* Space::new_dcto_cl(OopClosure* cl,
                                           CardTableModRefBS::PrecisionStyle precision,
                                           HeapWord* boundary) {
   return new DirtyCardToOopClosure(this, cl, precision, boundary);
 }
 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
                                                HeapWord* top_obj) {
   if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
     if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
       if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
         // An arrayOop is starting on the dirty card - since we do exact
         // store checks for objArrays we are done.
       } else {
         // Otherwise, it is possible that the object starting on the dirty
         // card spans the entire card, and that the store happened on a
         // later card.  Figure out where the object ends.
         assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
           "Block size and object size mismatch");
         top = top_obj + oop(top_obj)->size();
       }
     }
   } else {
     top = (_sp->toContiguousSpace())->top();
   }
   return top;
 }
 void Filtering_DCTOC::walk_mem_region(MemRegion mr,
                                       HeapWord* bottom,
                                       HeapWord* top) {
   // Note that this assumption won't hold if we have a concurrent
   // collector in this space, which may have freed up objects after
   // they were dirtied and before the stop-the-world GC that is
   // examining cards here.
   assert(bottom < top, "ought to be at least one obj on a dirty card.");
   if (_boundary != NULL) {
     // We have a boundary outside of which we don't want to look
     // at objects, so create a filtering closure around the
     // oop closure before walking the region.
     FilteringClosure filter(_boundary, _cl);
     walk_mem_region_with_cl(mr, bottom, top, &filter);
   } else {
     // No boundary, simply walk the heap with the oop closure.
     walk_mem_region_with_cl(mr, bottom, top, _cl);
   }
 }
 // We must replicate this so that the static type of "FilteringClosure"
 // (see above) is apparent at the oop_iterate calls.
 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr,        \
                                                    HeapWord* bottom,    \
                                                    HeapWord* top,       \
                                                    ClosureType* cl) {   \
   bottom += oop(bottom)->oop_iterate(cl, mr);                           \
   if (bottom < top) {                                                   \
     HeapWord* next_obj = bottom + oop(bottom)->size();                  \
     while (next_obj < top) {                                            \
       /* Bottom lies entirely below top, so we can call the */          \
       /* non-memRegion version of oop_iterate below. */                 \
       oop(bottom)->oop_iterate(cl);                                     \
       bottom = next_obj;                                                \
       next_obj = bottom + oop(bottom)->size();                          \
     }                                                                   \
     /* Last object. */                                                  \
     oop(bottom)->oop_iterate(cl, mr);                                   \
   }                                                                     \
 }
 // (There are only two of these, rather than N, because the split is due
 // only to the introduction of the FilteringClosure, a local part of the
 // impl of this abstraction.)
 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(OopClosure)
 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
 DirtyCardToOopClosure*
 ContiguousSpace::new_dcto_cl(OopClosure* cl,
                              CardTableModRefBS::PrecisionStyle precision,
                              HeapWord* boundary) {
   return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
 }
 void Space::initialize(MemRegion mr,
                        bool clear_space,
                        bool mangle_space) {
   HeapWord* bottom = mr.start();
   HeapWord* end    = mr.end();
   assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
          "invalid space boundaries");
   set_bottom(bottom);
   set_end(end);
   if (clear_space) clear(mangle_space);
 }
 void Space::clear(bool mangle_space) {
   if (ZapUnusedHeapArea && mangle_space) {
     mangle_unused_area();
   }
 }
 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
     _concurrent_iteration_safe_limit(NULL) {
   _mangler = new GenSpaceMangler(this);
 }
 ContiguousSpace::~ContiguousSpace() {
   delete _mangler;
 }
 void ContiguousSpace::initialize(MemRegion mr,
                                  bool clear_space,
                                  bool mangle_space)
 {
   CompactibleSpace::initialize(mr, clear_space, mangle_space);
   set_concurrent_iteration_safe_limit(top());
 }
 void ContiguousSpace::clear(bool mangle_space) {
   set_top(bottom());
   set_saved_mark();
   CompactibleSpace::clear(mangle_space);
 }
 bool Space::is_in(const void* p) const {
   HeapWord* b = block_start_const(p);
   return b != NULL && block_is_obj(b);
 }
 bool ContiguousSpace::is_in(const void* p) const {
   return _bottom <= p && p < _top;
 }
 bool ContiguousSpace::is_free_block(const HeapWord* p) const {
   return p >= _top;
 }
 void OffsetTableContigSpace::clear(bool mangle_space) {
   ContiguousSpace::clear(mangle_space);
   _offsets.initialize_threshold();
 }
 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
   Space::set_bottom(new_bottom);
   _offsets.set_bottom(new_bottom);
 }
 void OffsetTableContigSpace::set_end(HeapWord* new_end) {
   // Space should not advertize an increase in size
   // until after the underlying offest table has been enlarged.
   _offsets.resize(pointer_delta(new_end, bottom()));
   Space::set_end(new_end);
 }
 #ifndef PRODUCT
 void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
   mangler()->set_top_for_allocations(v);
 }
 void ContiguousSpace::set_top_for_allocations() {
   mangler()->set_top_for_allocations(top());
 }
 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
   mangler()->check_mangled_unused_area(limit);
 }
 void ContiguousSpace::check_mangled_unused_area_complete() {
   mangler()->check_mangled_unused_area_complete();
 }
 // Mangled only the unused space that has not previously
 // been mangled and that has not been allocated since being
 // mangled.
 void ContiguousSpace::mangle_unused_area() {
   mangler()->mangle_unused_area();
 }
 void ContiguousSpace::mangle_unused_area_complete() {
   mangler()->mangle_unused_area_complete();
 }
 void ContiguousSpace::mangle_region(MemRegion mr) {
   // Although this method uses SpaceMangler::mangle_region() which
   // is not specific to a space, the when the ContiguousSpace version
   // is called, it is always with regard to a space and this
   // bounds checking is appropriate.
   MemRegion space_mr(bottom(), end());
   assert(space_mr.contains(mr), "Mangling outside space");
   SpaceMangler::mangle_region(mr);
 }
 #endif  // NOT_PRODUCT
 void CompactibleSpace::initialize(MemRegion mr,
                                   bool clear_space,
                                   bool mangle_space) {
   Space::initialize(mr, clear_space, mangle_space);
   set_compaction_top(bottom());
   _next_compaction_space = NULL;
 }
 void CompactibleSpace::clear(bool mangle_space) {
   Space::clear(mangle_space);
   _compaction_top = bottom();
 }
 HeapWord* CompactibleSpace::forward(oop q, size_t size,
                                     CompactPoint* cp, HeapWord* compact_top) {
   // q is alive
   // First check if we should switch compaction space
   assert(this == cp->space, "'this' should be current compaction space.");
   size_t compaction_max_size = pointer_delta(end(), compact_top);
   while (size > compaction_max_size) {
     // switch to next compaction space
     cp->space->set_compaction_top(compact_top);
     cp->space = cp->space->next_compaction_space();
     if (cp->space == NULL) {
       cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
       assert(cp->gen != NULL, "compaction must succeed");
       cp->space = cp->gen->first_compaction_space();
       assert(cp->space != NULL, "generation must have a first compaction space");
     }
     compact_top = cp->space->bottom();
     cp->space->set_compaction_top(compact_top);
     cp->threshold = cp->space->initialize_threshold();
     compaction_max_size = pointer_delta(cp->space->end(), compact_top);
   }
   // store the forwarding pointer into the mark word
   if ((HeapWord*)q != compact_top) {
     q->forward_to(oop(compact_top));
     assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
   } else {
     // if the object isn't moving we can just set the mark to the default
     // mark and handle it specially later on.
     q->init_mark();
     assert(q->forwardee() == NULL, "should be forwarded to NULL");
   }
   VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(q, size));
   compact_top += size;
   // we need to update the offset table so that the beginnings of objects can be
   // found during scavenge.  Note that we are updating the offset table based on
   // where the object will be once the compaction phase finishes.
   if (compact_top > cp->threshold)
     cp->threshold =
       cp->space->cross_threshold(compact_top - size, compact_top);
   return compact_top;
 }
 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
                                         HeapWord* q, size_t deadlength) {
   if (allowed_deadspace_words >= deadlength) {
     allowed_deadspace_words -= deadlength;
     CollectedHeap::fill_with_object(q, deadlength);
     oop(q)->set_mark(oop(q)->mark()->set_marked());
     assert((int) deadlength == oop(q)->size(), "bad filler object size");
     // Recall that we required "q == compaction_top".
     return true;
   } else {
     allowed_deadspace_words = 0;
     return false;
   }
 }
 #define block_is_always_obj(q) true
 #define obj_size(q) oop(q)->size()
 #define adjust_obj_size(s) s
 void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
   SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
 }
 // Faster object search.
 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
   SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
 }
 void Space::adjust_pointers() {
   // adjust all the interior pointers to point at the new locations of objects
   // Used by MarkSweep::mark_sweep_phase3()
   // First check to see if there is any work to be done.
   if (used() == 0) {
     return;  // Nothing to do.
   }
   // Otherwise...
   HeapWord* q = bottom();
   HeapWord* t = end();
   debug_only(HeapWord* prev_q = NULL);
   while (q < t) {
     if (oop(q)->is_gc_marked()) {
       // q is alive
       VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q)));
       // point all the oops to the new location
       size_t size = oop(q)->adjust_pointers();
       VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers());
       debug_only(prev_q = q);
       VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size));
       q += size;
     } else {
       // q is not a live object.  But we're not in a compactible space,
       // So we don't have live ranges.
       debug_only(prev_q = q);
       q += block_size(q);
       assert(q > prev_q, "we should be moving forward through memory");
     }
   }
   assert(q == t, "just checking");
 }
 void CompactibleSpace::adjust_pointers() {
   // Check first is there is any work to do.
   if (used() == 0) {
     return;   // Nothing to do.
   }
   SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
 }
 void CompactibleSpace::compact() {
   SCAN_AND_COMPACT(obj_size);
 }
 void Space::print_short() const { print_short_on(tty); }
 void Space::print_short_on(outputStream* st) const {
   st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
               (int) ((double) used() * 100 / capacity()));
 }
 void Space::print() const { print_on(tty); }
 void Space::print_on(outputStream* st) const {
   print_short_on(st);
   st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
                 bottom(), end());
 }
 void ContiguousSpace::print_on(outputStream* st) const {
   print_short_on(st);
   st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
                 bottom(), top(), end());
 }
 void OffsetTableContigSpace::print_on(outputStream* st) const {
   print_short_on(st);
   st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
                 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
               bottom(), top(), _offsets.threshold(), end());
 }
 void ContiguousSpace::verify(bool allow_dirty) const {
   HeapWord* p = bottom();
   HeapWord* t = top();
   HeapWord* prev_p = NULL;
   while (p < t) {
     oop(p)->verify();
     prev_p = p;
     p += oop(p)->size();
   }
   guarantee(p == top(), "end of last object must match end of space");
   if (top() != end()) {
     guarantee(top() == block_start_const(end()-1) &&
               top() == block_start_const(top()),
               "top should be start of unallocated block, if it exists");
   }
 }
 void Space::oop_iterate(OopClosure* blk) {
   ObjectToOopClosure blk2(blk);
   object_iterate(&blk2);
 }
 HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) {
   guarantee(false, "NYI");
   return bottom();
 }
 HeapWord* Space::object_iterate_careful_m(MemRegion mr,
                                           ObjectClosureCareful* cl) {
   guarantee(false, "NYI");
   return bottom();
 }
 void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
   assert(!mr.is_empty(), "Should be non-empty");
   // We use MemRegion(bottom(), end()) rather than used_region() below
   // because the two are not necessarily equal for some kinds of
   // spaces, in particular, certain kinds of free list spaces.
   // We could use the more complicated but more precise:
   // MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
   // but the slight imprecision seems acceptable in the assertion check.
   assert(MemRegion(bottom(), end()).contains(mr),
          "Should be within used space");
   HeapWord* prev = cl->previous();   // max address from last time
   if (prev >= mr.end()) { // nothing to do
     return;
   }
   // This assert will not work when we go from cms space to perm
   // space, and use same closure. Easy fix deferred for later. XXX YSR
   // assert(prev == NULL || contains(prev), "Should be within space");
   bool last_was_obj_array = false;
   HeapWord *blk_start_addr, *region_start_addr;
   if (prev > mr.start()) {
     region_start_addr = prev;
     blk_start_addr    = prev;
     // The previous invocation may have pushed "prev" beyond the
     // last allocated block yet there may be still be blocks
     // in this region due to a particular coalescing policy.
     // Relax the assertion so that the case where the unallocated
     // block is maintained and "prev" is beyond the unallocated
     // block does not cause the assertion to fire.
     assert((BlockOffsetArrayUseUnallocatedBlock &&
             (!is_in(prev))) ||
            (blk_start_addr == block_start(region_start_addr)), "invariant");
   } else {
     region_start_addr = mr.start();
     blk_start_addr    = block_start(region_start_addr);
   }
   HeapWord* region_end_addr = mr.end();
   MemRegion derived_mr(region_start_addr, region_end_addr);
   while (blk_start_addr < region_end_addr) {
     const size_t size = block_size(blk_start_addr);
     if (block_is_obj(blk_start_addr)) {
       last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
     } else {
       last_was_obj_array = false;
     }
     blk_start_addr += size;
   }
   if (!last_was_obj_array) {
     assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
            "Should be within (closed) used space");
     assert(blk_start_addr > prev, "Invariant");
     cl->set_previous(blk_start_addr); // min address for next time
   }
 }
 bool Space::obj_is_alive(const HeapWord* p) const {
   assert (block_is_obj(p), "The address should point to an object");
   return true;
 }
 void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
   assert(!mr.is_empty(), "Should be non-empty");
   assert(used_region().contains(mr), "Should be within used space");
   HeapWord* prev = cl->previous();   // max address from last time
   if (prev >= mr.end()) { // nothing to do
     return;
   }
   // See comment above (in more general method above) in case you
   // happen to use this method.
   assert(prev == NULL || is_in_reserved(prev), "Should be within space");
   bool last_was_obj_array = false;
   HeapWord *obj_start_addr, *region_start_addr;
   if (prev > mr.start()) {
     region_start_addr = prev;
     obj_start_addr    = prev;
     assert(obj_start_addr == block_start(region_start_addr), "invariant");
   } else {
     region_start_addr = mr.start();
     obj_start_addr    = block_start(region_start_addr);
   }
   HeapWord* region_end_addr = mr.end();
   MemRegion derived_mr(region_start_addr, region_end_addr);
   while (obj_start_addr < region_end_addr) {
     oop obj = oop(obj_start_addr);
     const size_t size = obj->size();
     last_was_obj_array = cl->do_object_bm(obj, derived_mr);
     obj_start_addr += size;
   }
   if (!last_was_obj_array) {
     assert((bottom() <= obj_start_addr)  && (obj_start_addr <= end()),
            "Should be within (closed) used space");
     assert(obj_start_addr > prev, "Invariant");
     cl->set_previous(obj_start_addr); // min address for next time
   }
 }
 #ifndef SERIALGC
 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix)         \
                                                                             \
   void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
     HeapWord* obj_addr = mr.start();                                        \
     HeapWord* t = mr.end();                                                 \
     while (obj_addr < t) {                                                  \
       assert(oop(obj_addr)->is_oop(), "Should be an oop");                  \
       obj_addr += oop(obj_addr)->oop_iterate(blk);                          \
     }                                                                       \
   }
   ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
 #undef ContigSpace_PAR_OOP_ITERATE_DEFN
 #endif // SERIALGC
 void ContiguousSpace::oop_iterate(OopClosure* blk) {
   if (is_empty()) return;
   HeapWord* obj_addr = bottom();
   HeapWord* t = top();
   // Could call objects iterate, but this is easier.
   while (obj_addr < t) {
     obj_addr += oop(obj_addr)->oop_iterate(blk);
   }
 }
 void ContiguousSpace::oop_iterate(MemRegion mr, OopClosure* blk) {
   if (is_empty()) {
     return;
   }
   MemRegion cur = MemRegion(bottom(), top());
   mr = mr.intersection(cur);
   if (mr.is_empty()) {
     return;
   }
   if (mr.equals(cur)) {
     oop_iterate(blk);
     return;
   }
   assert(mr.end() <= top(), "just took an intersection above");
   HeapWord* obj_addr = block_start(mr.start());
   HeapWord* t = mr.end();
   // Handle first object specially.
   oop obj = oop(obj_addr);
   SpaceMemRegionOopsIterClosure smr_blk(blk, mr);
   obj_addr += obj->oop_iterate(&smr_blk);
   while (obj_addr < t) {
     oop obj = oop(obj_addr);
     assert(obj->is_oop(), "expected an oop");
     obj_addr += obj->size();
     // If "obj_addr" is not greater than top, then the
     // entire object "obj" is within the region.
     if (obj_addr <= t) {
       obj->oop_iterate(blk);
     } else {
       // "obj" extends beyond end of region
       obj->oop_iterate(&smr_blk);
       break;
     }
   };
 }
 void ContiguousSpace::object_iterate(ObjectClosure* blk) {
   if (is_empty()) return;
   WaterMark bm = bottom_mark();
   object_iterate_from(bm, blk);
 }
 // For a continguous space object_iterate() and safe_object_iterate()
 // are the same.
 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
   object_iterate(blk);
 }
 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
   assert(mark.space() == this, "Mark does not match space");
   HeapWord* p = mark.point();
   while (p < top()) {
     blk->do_object(oop(p));
     p += oop(p)->size();
   }
 }
 HeapWord*
 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
   HeapWord * limit = concurrent_iteration_safe_limit();
   assert(limit <= top(), "sanity check");
   for (HeapWord* p = bottom(); p < limit;) {
     size_t size = blk->do_object_careful(oop(p));
     if (size == 0) {
       return p;  // failed at p
     } else {
       p += size;
     }
   }
   return NULL; // all done
 }
 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix)  \
                                                                           \
 void ContiguousSpace::                                                    \
 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) {            \
   HeapWord* t;                                                            \
   HeapWord* p = saved_mark_word();                                        \
   assert(p != NULL, "expected saved mark");                               \
                                                                           \
   const intx interval = PrefetchScanIntervalInBytes;                      \
   do {                                                                    \
     t = top();                                                            \
     while (p < t) {                                                       \
       Prefetch::write(p, interval);                                       \
       debug_only(HeapWord* prev = p);                                     \
       oop m = oop(p);                                                     \
       p += m->oop_iterate(blk);                                           \
     }                                                                     \
   } while (t < top());                                                    \
                                                                           \
   set_saved_mark_word(p);                                                 \
 }
 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
 // Very general, slow implementation.
 HeapWord* ContiguousSpace::block_start_const(const void* p) const {
   assert(MemRegion(bottom(), end()).contains(p), "p not in space");
   if (p >= top()) {
     return top();
   } else {
     HeapWord* last = bottom();
     HeapWord* cur = last;
     while (cur <= p) {
       last = cur;
       cur += oop(cur)->size();
     }
     assert(oop(last)->is_oop(), "Should be an object start");
     return last;
   }
 }
 size_t ContiguousSpace::block_size(const HeapWord* p) const {
   assert(MemRegion(bottom(), end()).contains(p), "p not in space");
   HeapWord* current_top = top();
   assert(p <= current_top, "p is not a block start");
   assert(p == current_top || oop(p)->is_oop(), "p is not a block start");
   if (p < current_top)
     return oop(p)->size();
   else {
     assert(p == current_top, "just checking");
     return pointer_delta(end(), (HeapWord*) p);
   }
 }
 // This version requires locking.
 inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
                                                 HeapWord* const end_value) {
   // In G1 there are places where a GC worker can allocates into a
   // region using this serial allocation code without being prone to a
   // race with other GC workers (we ensure that no other GC worker can
   // access the same region at the same time). So the assert below is
   // too strong in the case of G1.
   assert(Heap_lock->owned_by_self() ||
          (SafepointSynchronize::is_at_safepoint() &&
                                (Thread::current()->is_VM_thread() || UseG1GC)),
          "not locked");
   HeapWord* obj = top();
   if (pointer_delta(end_value, obj) >= size) {
     HeapWord* new_top = obj + size;
     set_top(new_top);
     assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
     return obj;
   } else {
     return NULL;
   }
 }
 // This version is lock-free.
 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
                                                     HeapWord* const end_value) {
   do {
     HeapWord* obj = top();
     if (pointer_delta(end_value, obj) >= size) {
       HeapWord* new_top = obj + size;
       HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
       // result can be one of two:
       //  the old top value: the exchange succeeded
       //  otherwise: the new value of the top is returned.
       if (result == obj) {
         assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
         return obj;
       }
     } else {
       return NULL;
     }
   } while (true);
 }
 // Requires locking.
 HeapWord* ContiguousSpace::allocate(size_t size) {
   return allocate_impl(size, end());
 }
 // Lock-free.
 HeapWord* ContiguousSpace::par_allocate(size_t size) {
   return par_allocate_impl(size, end());
 }
 void ContiguousSpace::allocate_temporary_filler(int factor) {
   // allocate temporary type array decreasing free size with factor 'factor'
   assert(factor >= 0, "just checking");
   size_t size = pointer_delta(end(), top());
   // if space is full, return
   if (size == 0) return;
   if (factor > 0) {
     size -= size/factor;
   }
   size = align_object_size(size);
   const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
   if (size >= (size_t)align_object_size(array_header_size)) {
     size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
     // allocate uninitialized int array
     typeArrayOop t = (typeArrayOop) allocate(size);
     assert(t != NULL, "allocation should succeed");
     t->set_mark(markOopDesc::prototype());
     t->set_klass(Universe::intArrayKlassObj());
     t->set_length((int)length);
   } else {
     assert(size == CollectedHeap::min_fill_size(),
            "size for smallest fake object doesn't match");
     instanceOop obj = (instanceOop) allocate(size);
     obj->set_mark(markOopDesc::prototype());
     obj->set_klass_gap(0);
     obj->set_klass(SystemDictionary::Object_klass());
   }
 }
 void EdenSpace::clear(bool mangle_space) {
   ContiguousSpace::clear(mangle_space);
   set_soft_end(end());
 }
 // Requires locking.
 HeapWord* EdenSpace::allocate(size_t size) {
   return allocate_impl(size, soft_end());
 }
 // Lock-free.
 HeapWord* EdenSpace::par_allocate(size_t size) {
   return par_allocate_impl(size, soft_end());
 }
 HeapWord* ConcEdenSpace::par_allocate(size_t size)
 {
   do {
     // The invariant is top() should be read before end() because
     // top() can't be greater than end(), so if an update of _soft_end
     // occurs between 'end_val = end();' and 'top_val = top();' top()
     // also can grow up to the new end() and the condition
     // 'top_val > end_val' is true. To ensure the loading order
     // OrderAccess::loadload() is required after top() read.
     HeapWord* obj = top();
     OrderAccess::loadload();
     if (pointer_delta(*soft_end_addr(), obj) >= size) {
       HeapWord* new_top = obj + size;
       HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
       // result can be one of two:
       //  the old top value: the exchange succeeded
       //  otherwise: the new value of the top is returned.
       if (result == obj) {
         assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
         return obj;
       }
     } else {
       return NULL;
     }
   } while (true);
 }
 HeapWord* OffsetTableContigSpace::initialize_threshold() {
   return _offsets.initialize_threshold();
 }
 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
   _offsets.alloc_block(start, end);
   return _offsets.threshold();
 }
 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
                                                MemRegion mr) :
   _offsets(sharedOffsetArray, mr),
   _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
 {
   _offsets.set_contig_space(this);
   initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
 }
 class VerifyOldOopClosure : public OopClosure {
  public:
   oop  _the_obj;
   bool _allow_dirty;
   void do_oop(oop* p) {
     _the_obj->verify_old_oop(p, _allow_dirty);
   }
   void do_oop(narrowOop* p) {
     _the_obj->verify_old_oop(p, _allow_dirty);
   }
 };
 #define OBJ_SAMPLE_INTERVAL 0
 #define BLOCK_SAMPLE_INTERVAL 100
 void OffsetTableContigSpace::verify(bool allow_dirty) const {
   HeapWord* p = bottom();
   HeapWord* prev_p = NULL;
   VerifyOldOopClosure blk;      // Does this do anything?
   blk._allow_dirty = allow_dirty;
   int objs = 0;
   int blocks = 0;
   if (VerifyObjectStartArray) {
     _offsets.verify();
   }
   while (p < top()) {
     size_t size = oop(p)->size();
     // For a sampling of objects in the space, find it using the
     // block offset table.
     if (blocks == BLOCK_SAMPLE_INTERVAL) {
       guarantee(p == block_start_const(p + (size/2)),
                 "check offset computation");
       blocks = 0;
     } else {
       blocks++;
     }
     if (objs == OBJ_SAMPLE_INTERVAL) {
       oop(p)->verify();
       blk._the_obj = oop(p);
       oop(p)->oop_iterate(&blk);
       objs = 0;
     } else {
       objs++;
     }
     prev_p = p;
     p += size;
   }
   guarantee(p == top(), "end of last object must match end of space");
 }
 void OffsetTableContigSpace::serialize_block_offset_array_offsets(
                                                       SerializeOopClosure* soc) {
   _offsets.serialize(soc);
 }
 size_t TenuredSpace::allowed_dead_ratio() const {
   return MarkSweepDeadRatio;
 }
 size_t ContigPermSpace::allowed_dead_ratio() const {
   return PermMarkSweepDeadRatio;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/space.cpp@d06a2d7fcd5b (annotated)

src/share/vm/memory/space.cpp