changeset 1643:1b0104ab1e5e

Merge
author tonyp
date Thu, 19 Aug 2010 14:08:58 -0400
parents 495caa35b1b5 effb55808a18
children 09cdb1e1c77b
files
diffstat 18 files changed, 440 insertions(+), 183 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -402,6 +402,29 @@
   return res;
 }
 
+void LinearAllocBlock::print_on(outputStream* st) const {
+  st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT
+            ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT,
+            _ptr, _word_size, _refillSize, _allocation_size_limit);
+}
+
+void CompactibleFreeListSpace::print_on(outputStream* st) const {
+  st->print_cr("COMPACTIBLE FREELIST SPACE");
+  st->print_cr(" Space:");
+  Space::print_on(st);
+
+  st->print_cr("promoInfo:");
+  _promoInfo.print_on(st);
+
+  st->print_cr("_smallLinearAllocBlock");
+  _smallLinearAllocBlock.print_on(st);
+
+  // dump_memory_block(_smallLinearAllocBlock->_ptr, 128);
+
+  st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s",
+               _fitStrategy?"true":"false", _adaptive_freelists?"true":"false");
+}
+
 void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)
 const {
   reportIndexedFreeListStatistics();
@@ -557,13 +580,15 @@
 void CompactibleFreeListSpace::set_end(HeapWord* value) {
   HeapWord* prevEnd = end();
   assert(prevEnd != value, "unnecessary set_end call");
-  assert(prevEnd == NULL || value >= unallocated_block(), "New end is below unallocated block");
+  assert(prevEnd == NULL || !BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),
+        "New end is below unallocated block");
   _end = value;
   if (prevEnd != NULL) {
     // Resize the underlying block offset table.
     _bt.resize(pointer_delta(value, bottom()));
     if (value <= prevEnd) {
-      assert(value >= unallocated_block(), "New end is below unallocated block");
+      assert(!BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),
+             "New end is below unallocated block");
     } else {
       // Now, take this new chunk and add it to the free blocks.
       // Note that the BOT has not yet been updated for this block.
@@ -938,7 +963,6 @@
 
 size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const {
   NOT_PRODUCT(verify_objects_initialized());
-  assert(MemRegion(bottom(), end()).contains(p), "p not in space");
   // This must be volatile, or else there is a danger that the compiler
   // will compile the code below into a sometimes-infinite loop, by keeping
   // the value read the first time in a register.
@@ -957,7 +981,7 @@
       // must read from what 'p' points to in each loop.
       klassOop k = ((volatile oopDesc*)p)->klass_or_null();
       if (k != NULL) {
-        assert(k->is_oop(true /* ignore mark word */), "Should really be klass oop.");
+        assert(k->is_oop(true /* ignore mark word */), "Should be klass oop");
         oop o = (oop)p;
         assert(o->is_parsable(), "Should be parsable");
         assert(o->is_oop(true /* ignore mark word */), "Should be an oop.");
@@ -1231,7 +1255,6 @@
         // satisfy the request.  This is different that
         // evm.
         // Don't record chunk off a LinAB?  smallSplitBirth(size);
-
     } else {
       // Raid the exact free lists larger than size, even if they are not
       // overpopulated.
@@ -1449,6 +1472,7 @@
     // Update BOT last so that other (parallel) GC threads see a consistent
     // view of the BOT and free blocks.
     // Above must occur before BOT is updated below.
+    OrderAccess::storestore();
     _bt.split_block(res, blk_size, size);  // adjust block offset table
   }
   return res;
@@ -1477,6 +1501,7 @@
     // Update BOT last so that other (parallel) GC threads see a consistent
     // view of the BOT and free blocks.
     // Above must occur before BOT is updated below.
+    OrderAccess::storestore();
     _bt.split_block(res, blk_size, size);  // adjust block offset table
     _bt.allocated(res, size);
   }
@@ -1856,6 +1881,8 @@
   ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
   // Above must occur before BOT is updated below.
   // adjust block offset table
+  OrderAccess::storestore();
+  assert(chunk->isFree() && ffc->isFree(), "Error");
   _bt.split_block((HeapWord*)chunk, chunk->size(), new_size);
   if (rem_size < SmallForDictionary) {
     bool is_par = (SharedHeap::heap()->n_par_threads() > 0);
@@ -1911,8 +1938,7 @@
   // mark the "end" of the used space at the time of this call;
   // note, however, that promoted objects from this point
   // on are tracked in the _promoInfo below.
-  set_saved_mark_word(BlockOffsetArrayUseUnallocatedBlock ?
-                      unallocated_block() : end());
+  set_saved_mark_word(unallocated_block());
   // inform allocator that promotions should be tracked.
   assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");
   _promoInfo.startTrackingPromotions();
@@ -2238,8 +2264,7 @@
 }
 
 void CompactibleFreeListSpace::print() const {
-  tty->print(" CompactibleFreeListSpace");
-  Space::print();
+  Space::print_on(tty);
 }
 
 void CompactibleFreeListSpace::prepare_for_verify() {
@@ -2253,18 +2278,28 @@
  private:
   const CompactibleFreeListSpace* _sp;
   const MemRegion                 _span;
+  HeapWord*                       _last_addr;
+  size_t                          _last_size;
+  bool                            _last_was_obj;
+  bool                            _last_was_live;
 
  public:
   VerifyAllBlksClosure(const CompactibleFreeListSpace* sp,
-    MemRegion span) :  _sp(sp), _span(span) { }
+    MemRegion span) :  _sp(sp), _span(span),
+                       _last_addr(NULL), _last_size(0),
+                       _last_was_obj(false), _last_was_live(false) { }
 
   virtual size_t do_blk(HeapWord* addr) {
     size_t res;
+    bool   was_obj  = false;
+    bool   was_live = false;
     if (_sp->block_is_obj(addr)) {
+      was_obj = true;
       oop p = oop(addr);
       guarantee(p->is_oop(), "Should be an oop");
       res = _sp->adjustObjectSize(p->size());
       if (_sp->obj_is_alive(addr)) {
+        was_live = true;
         p->verify();
       }
     } else {
@@ -2275,7 +2310,20 @@
                   "Chunk should be on a free list");
       }
     }
-    guarantee(res != 0, "Livelock: no rank reduction!");
+    if (res == 0) {
+      gclog_or_tty->print_cr("Livelock: no rank reduction!");
+      gclog_or_tty->print_cr(
+        " Current:  addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n"
+        " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n",
+        addr,       res,        was_obj      ?"true":"false", was_live      ?"true":"false",
+        _last_addr, _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false");
+      _sp->print_on(gclog_or_tty);
+      guarantee(false, "Seppuku!");
+    }
+    _last_addr = addr;
+    _last_size = res;
+    _last_was_obj  = was_obj;
+    _last_was_live = was_live;
     return res;
   }
 };
@@ -2521,7 +2569,7 @@
 
 HeapWord* CFLS_LAB::alloc(size_t word_sz) {
   FreeChunk* res;
-  word_sz = _cfls->adjustObjectSize(word_sz);
+  guarantee(word_sz == _cfls->adjustObjectSize(word_sz), "Error");
   if (word_sz >=  CompactibleFreeListSpace::IndexSetSize) {
     // This locking manages sync with other large object allocations.
     MutexLockerEx x(_cfls->parDictionaryAllocLock(),
@@ -2667,12 +2715,12 @@
          (cur_sz < CompactibleFreeListSpace::IndexSetSize) &&
          (CMSSplitIndexedFreeListBlocks || k <= 1);
          k++, cur_sz = k * word_sz) {
-      FreeList* gfl = &_indexedFreeList[cur_sz];
       FreeList fl_for_cur_sz;  // Empty.
       fl_for_cur_sz.set_size(cur_sz);
       {
         MutexLockerEx x(_indexedFreeListParLocks[cur_sz],
                         Mutex::_no_safepoint_check_flag);
+        FreeList* gfl = &_indexedFreeList[cur_sz];
         if (gfl->count() != 0) {
           // nn is the number of chunks of size cur_sz that
           // we'd need to split k-ways each, in order to create
@@ -2685,9 +2733,9 @@
             // we increment the split death count by the number of blocks
             // we just took from the cur_sz-size blocks list and which
             // we will be splitting below.
-            ssize_t deaths = _indexedFreeList[cur_sz].splitDeaths() +
+            ssize_t deaths = gfl->splitDeaths() +
                              fl_for_cur_sz.count();
-            _indexedFreeList[cur_sz].set_splitDeaths(deaths);
+            gfl->set_splitDeaths(deaths);
           }
         }
       }
@@ -2703,18 +2751,25 @@
             // access the main chunk sees it as a single free block until we
             // change it.
             size_t fc_size = fc->size();
+            assert(fc->isFree(), "Error");
             for (int i = k-1; i >= 0; i--) {
               FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
+              assert((i != 0) ||
+                        ((fc == ffc) && ffc->isFree() &&
+                         (ffc->size() == k*word_sz) && (fc_size == word_sz)),
+                        "Counting error");
               ffc->setSize(word_sz);
+              ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
               ffc->linkNext(NULL);
-              ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
               // Above must occur before BOT is updated below.
-              // splitting from the right, fc_size == (k - i + 1) * wordsize
-              _bt.mark_block((HeapWord*)ffc, word_sz);
+              OrderAccess::storestore();
+              // splitting from the right, fc_size == i * word_sz
+              _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */);
               fc_size -= word_sz;
-              _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size());
+              assert(fc_size == i*word_sz, "Error");
+              _bt.verify_not_unallocated((HeapWord*)ffc, word_sz);
               _bt.verify_single_block((HeapWord*)fc, fc_size);
-              _bt.verify_single_block((HeapWord*)ffc, ffc->size());
+              _bt.verify_single_block((HeapWord*)ffc, word_sz);
               // Push this on "fl".
               fl->returnChunkAtHead(ffc);
             }
@@ -2744,7 +2799,7 @@
                                   _dictionary->minSize()),
                                   FreeBlockDictionary::atLeast);
       if (fc != NULL) {
-        _bt.allocated((HeapWord*)fc, fc->size());  // update _unallocated_blk
+        _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */);  // update _unallocated_blk
         dictionary()->dictCensusUpdate(fc->size(),
                                        true /*split*/,
                                        false /*birth*/);
@@ -2754,8 +2809,10 @@
       }
     }
     if (fc == NULL) return;
+    // Otherwise, split up that block.
     assert((ssize_t)n >= 1, "Control point invariant");
-    // Otherwise, split up that block.
+    assert(fc->isFree(), "Error: should be a free block");
+    _bt.verify_single_block((HeapWord*)fc, fc->size());
     const size_t nn = fc->size() / word_sz;
     n = MIN2(nn, n);
     assert((ssize_t)n >= 1, "Control point invariant");
@@ -2773,6 +2830,7 @@
     // dictionary and return, leaving "fl" empty.
     if (n == 0) {
       returnChunkToDictionary(fc);
+      assert(fl->count() == 0, "We never allocated any blocks");
       return;
     }
 
@@ -2785,11 +2843,14 @@
       size_t prefix_size = n * word_sz;
       rem_fc = (FreeChunk*)((HeapWord*)fc + prefix_size);
       rem_fc->setSize(rem);
+      rem_fc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
       rem_fc->linkNext(NULL);
-      rem_fc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
       // Above must occur before BOT is updated below.
       assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error");
+      OrderAccess::storestore();
       _bt.split_block((HeapWord*)fc, fc->size(), prefix_size);
+      assert(fc->isFree(), "Error");
+      fc->setSize(prefix_size);
       if (rem >= IndexSetSize) {
         returnChunkToDictionary(rem_fc);
         dictionary()->dictCensusUpdate(rem, true /*split*/, true /*birth*/);
@@ -2815,11 +2876,12 @@
   for (ssize_t i = n-1; i > 0; i--) {
     FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
     ffc->setSize(word_sz);
+    ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
     ffc->linkNext(NULL);
-    ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
     // Above must occur before BOT is updated below.
+    OrderAccess::storestore();
     // splitting from the right, fc_size == (n - i + 1) * wordsize
-    _bt.mark_block((HeapWord*)ffc, word_sz);
+    _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */);
     fc_size -= word_sz;
     _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size());
     _bt.verify_single_block((HeapWord*)ffc, ffc->size());
@@ -2828,9 +2890,11 @@
     fl->returnChunkAtHead(ffc);
   }
   // First chunk
+  assert(fc->isFree() && fc->size() == n*word_sz, "Error: should still be a free block");
+  // The blocks above should show their new sizes before the first block below
   fc->setSize(word_sz);
+  fc->linkPrev(NULL);    // idempotent wrt free-ness, see assert above
   fc->linkNext(NULL);
-  fc->linkPrev(NULL);
   _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
   _bt.verify_single_block((HeapWord*)fc, fc->size());
   fl->returnChunkAtHead(fc);
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -48,6 +48,8 @@
   size_t    _word_size;
   size_t    _refillSize;
   size_t    _allocation_size_limit;  // largest size that will be allocated
+
+  void print_on(outputStream* st) const;
 };
 
 // Concrete subclass of CompactibleSpace that implements
@@ -249,10 +251,14 @@
   size_t     numFreeBlocksInIndexedFreeLists() const;
   // Accessor
   HeapWord* unallocated_block() const {
-    HeapWord* ub = _bt.unallocated_block();
-    assert(ub >= bottom() &&
-           ub <= end(), "space invariant");
-    return ub;
+    if (BlockOffsetArrayUseUnallocatedBlock) {
+      HeapWord* ub = _bt.unallocated_block();
+      assert(ub >= bottom() &&
+             ub <= end(), "space invariant");
+      return ub;
+    } else {
+      return end();
+    }
   }
   void freed(HeapWord* start, size_t size) {
     _bt.freed(start, size);
@@ -476,6 +482,7 @@
 
   // Debugging support
   void print()                            const;
+  void print_on(outputStream* st)         const;
   void prepare_for_verify();
   void verify(bool allow_dirty)           const;
   void verifyFreeLists()                  const PRODUCT_RETURN;
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1019,7 +1019,7 @@
 }
 
 HeapWord* ConcurrentMarkSweepGeneration::have_lock_and_allocate(size_t size,
-                                                  bool   tlab) {
+                                                  bool   tlab /* ignored */) {
   assert_lock_strong(freelistLock());
   size_t adjustedSize = CompactibleFreeListSpace::adjustObjectSize(size);
   HeapWord* res = cmsSpace()->allocate(adjustedSize);
@@ -1032,6 +1032,11 @@
   // allowing the object to be blackened (and its references scanned)
   // either during a preclean phase or at the final checkpoint.
   if (res != NULL) {
+    // We may block here with an uninitialized object with
+    // its mark-bit or P-bits not yet set. Such objects need
+    // to be safely navigable by block_start().
+    assert(oop(res)->klass_or_null() == NULL, "Object should be uninitialized here.");
+    assert(!((FreeChunk*)res)->isFree(), "Error, block will look free but show wrong size");
     collector()->direct_allocated(res, adjustedSize);
     _direct_allocated_words += adjustedSize;
     // allocation counters
@@ -1061,8 +1066,14 @@
     // [see comments preceding SweepClosure::do_blk() below for details]
     // 1. need to mark the object as live so it isn't collected
     // 2. need to mark the 2nd bit to indicate the object may be uninitialized
-    // 3. need to mark the end of the object so sweeper can skip over it
-    //    if it's uninitialized when the sweeper reaches it.
+    // 3. need to mark the end of the object so marking, precleaning or sweeping
+    //    can skip over uninitialized or unparsable objects. An allocated
+    //    object is considered uninitialized for our purposes as long as
+    //    its klass word is NULL. (Unparsable objects are those which are
+    //    initialized in the sense just described, but whose sizes can still
+    //    not be correctly determined. Note that the class of unparsable objects
+    //    can only occur in the perm gen. All old gen objects are parsable
+    //    as soon as they are initialized.)
     _markBitMap.mark(start);          // object is live
     _markBitMap.mark(start + 1);      // object is potentially uninitialized?
     _markBitMap.mark(start + size - 1);
@@ -1088,7 +1099,13 @@
     // We don't need to mark the object as uninitialized (as
     // in direct_allocated above) because this is being done with the
     // world stopped and the object will be initialized by the
-    // time the sweeper gets to look at it.
+    // time the marking, precleaning or sweeping get to look at it.
+    // But see the code for copying objects into the CMS generation,
+    // where we need to ensure that concurrent readers of the
+    // block offset table are able to safely navigate a block that
+    // is in flux from being free to being allocated (and in
+    // transition while being copied into) and subsequently
+    // becoming a bona-fide object when the copy/promotion is complete.
     assert(SafepointSynchronize::is_at_safepoint(),
            "expect promotion only at safepoints");
 
@@ -1304,6 +1321,48 @@
   return collector()->allocation_limit_reached(space, top, word_sz);
 }
 
+// IMPORTANT: Notes on object size recognition in CMS.
+// ---------------------------------------------------
+// A block of storage in the CMS generation is always in
+// one of three states. A free block (FREE), an allocated
+// object (OBJECT) whose size() method reports the correct size,
+// and an intermediate state (TRANSIENT) in which its size cannot
+// be accurately determined.
+// STATE IDENTIFICATION:   (32 bit and 64 bit w/o COOPS)
+// -----------------------------------------------------
+// FREE:      klass_word & 1 == 1; mark_word holds block size
+//
+// OBJECT:    klass_word installed; klass_word != 0 && klass_word & 0 == 0;
+//            obj->size() computes correct size
+//            [Perm Gen objects needs to be "parsable" before they can be navigated]
+//
+// TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT
+//
+// STATE IDENTIFICATION: (64 bit+COOPS)
+// ------------------------------------
+// FREE:      mark_word & CMS_FREE_BIT == 1; mark_word & ~CMS_FREE_BIT gives block_size
+//
+// OBJECT:    klass_word installed; klass_word != 0;
+//            obj->size() computes correct size
+//            [Perm Gen comment above continues to hold]
+//
+// TRANSIENT: klass_word == 0; size is indeterminate until we become an OBJECT
+//
+//
+// STATE TRANSITION DIAGRAM
+//
+//        mut / parnew                     mut  /  parnew
+// FREE --------------------> TRANSIENT ---------------------> OBJECT --|
+//  ^                                                                   |
+//  |------------------------ DEAD <------------------------------------|
+//         sweep                            mut
+//
+// While a block is in TRANSIENT state its size cannot be determined
+// so readers will either need to come back later or stall until
+// the size can be determined. Note that for the case of direct
+// allocation, P-bits, when available, may be used to determine the
+// size of an object that may not yet have been initialized.
+
 // Things to support parallel young-gen collection.
 oop
 ConcurrentMarkSweepGeneration::par_promote(int thread_num,
@@ -1331,33 +1390,39 @@
     }
   }
   assert(promoInfo->has_spooling_space(), "Control point invariant");
-  HeapWord* obj_ptr = ps->lab.alloc(word_sz);
+  const size_t alloc_sz = CompactibleFreeListSpace::adjustObjectSize(word_sz);
+  HeapWord* obj_ptr = ps->lab.alloc(alloc_sz);
   if (obj_ptr == NULL) {
-     obj_ptr = expand_and_par_lab_allocate(ps, word_sz);
+     obj_ptr = expand_and_par_lab_allocate(ps, alloc_sz);
      if (obj_ptr == NULL) {
        return NULL;
      }
   }
   oop obj = oop(obj_ptr);
+  OrderAccess::storestore();
   assert(obj->klass_or_null() == NULL, "Object should be uninitialized here.");
+  assert(!((FreeChunk*)obj_ptr)->isFree(), "Error, block will look free but show wrong size");
+  // IMPORTANT: See note on object initialization for CMS above.
   // Otherwise, copy the object.  Here we must be careful to insert the
   // klass pointer last, since this marks the block as an allocated object.
   // Except with compressed oops it's the mark word.
   HeapWord* old_ptr = (HeapWord*)old;
+  // Restore the mark word copied above.
+  obj->set_mark(m);
+  assert(obj->klass_or_null() == NULL, "Object should be uninitialized here.");
+  assert(!((FreeChunk*)obj_ptr)->isFree(), "Error, block will look free but show wrong size");
+  OrderAccess::storestore();
+
+  if (UseCompressedOops) {
+    // Copy gap missed by (aligned) header size calculation below
+    obj->set_klass_gap(old->klass_gap());
+  }
   if (word_sz > (size_t)oopDesc::header_size()) {
     Copy::aligned_disjoint_words(old_ptr + oopDesc::header_size(),
                                  obj_ptr + oopDesc::header_size(),
                                  word_sz - oopDesc::header_size());
   }
 
-  if (UseCompressedOops) {
-    // Copy gap missed by (aligned) header size calculation above
-    obj->set_klass_gap(old->klass_gap());
-  }
-
-  // Restore the mark word copied above.
-  obj->set_mark(m);
-
   // Now we can track the promoted object, if necessary.  We take care
   // to delay the transition from uninitialized to full object
   // (i.e., insertion of klass pointer) until after, so that it
@@ -1365,18 +1430,22 @@
   if (promoInfo->tracking()) {
     promoInfo->track((PromotedObject*)obj, old->klass());
   }
+  assert(obj->klass_or_null() == NULL, "Object should be uninitialized here.");
+  assert(!((FreeChunk*)obj_ptr)->isFree(), "Error, block will look free but show wrong size");
+  assert(old->is_oop(), "Will use and dereference old klass ptr below");
 
   // Finally, install the klass pointer (this should be volatile).
+  OrderAccess::storestore();
   obj->set_klass(old->klass());
-
-  assert(old->is_oop(), "Will dereference klass ptr below");
+  // We should now be able to calculate the right size for this object
+  assert(obj->is_oop() && obj->size() == (int)word_sz, "Error, incorrect size computed for promoted object");
+
   collector()->promoted(true,          // parallel
                         obj_ptr, old->is_objArray(), word_sz);
 
   NOT_PRODUCT(
-    Atomic::inc(&_numObjectsPromoted);
-    Atomic::add((jint)CompactibleFreeListSpace::adjustObjectSize(obj->size()),
-                &_numWordsPromoted);
+    Atomic::inc_ptr(&_numObjectsPromoted);
+    Atomic::add_ptr(alloc_sz, &_numWordsPromoted);
   )
 
   return obj;
@@ -7868,14 +7937,20 @@
   FreeChunk* fc = (FreeChunk*)addr;
   size_t res;
 
-  // check if we are done sweepinrg
-  if (addr == _limit) { // we have swept up to the limit, do nothing more
+  // Check if we are done sweeping. Below we check "addr >= _limit" rather
+  // than "addr == _limit" because although _limit was a block boundary when
+  // we started the sweep, it may no longer be one because heap expansion
+  // may have caused us to coalesce the block ending at the address _limit
+  // with a newly expanded chunk (this happens when _limit was set to the
+  // previous _end of the space), so we may have stepped past _limit; see CR 6977970.
+  if (addr >= _limit) { // we have swept up to or past the limit, do nothing more
     assert(_limit >= _sp->bottom() && _limit <= _sp->end(),
            "sweep _limit out of bounds");
+    assert(addr < _sp->end(), "addr out of bounds");
     // help the closure application finish
-    return pointer_delta(_sp->end(), _limit);
-  }
-  assert(addr <= _limit, "sweep invariant");
+    return pointer_delta(_sp->end(), addr);
+  }
+  assert(addr < _limit, "sweep invariant");
 
   // check if we should yield
   do_yield_check(addr);
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1010,10 +1010,10 @@
 
   // Non-product stat counters
   NOT_PRODUCT(
-    int _numObjectsPromoted;
-    int _numWordsPromoted;
-    int _numObjectsAllocated;
-    int _numWordsAllocated;
+    size_t _numObjectsPromoted;
+    size_t _numWordsPromoted;
+    size_t _numObjectsAllocated;
+    size_t _numWordsAllocated;
   )
 
   // Used for sizing decisions
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/freeChunk.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/freeChunk.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -110,15 +110,21 @@
   }
   void linkNext(FreeChunk* ptr) { _next = ptr; }
   void linkPrev(FreeChunk* ptr) {
-     LP64_ONLY(if (UseCompressedOops) _prev = ptr; else)
-     _prev = (FreeChunk*)((intptr_t)ptr | 0x1);
+    LP64_ONLY(if (UseCompressedOops) _prev = ptr; else)
+    _prev = (FreeChunk*)((intptr_t)ptr | 0x1);
   }
   void clearPrev()              { _prev = NULL; }
   void clearNext()              { _next = NULL; }
   void markNotFree() {
-   LP64_ONLY(if (UseCompressedOops) set_mark(markOopDesc::prototype());)
-   // Also set _prev to null
-   _prev = NULL;
+    // Set _prev (klass) to null before (if) clearing the mark word below
+    _prev = NULL;
+#ifdef _LP64
+    if (UseCompressedOops) {
+      OrderAccess::storestore();
+      set_mark(markOopDesc::prototype());
+    }
+#endif
+    assert(!isFree(), "Error");
   }
 
   // Return the address past the end of this chunk
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -330,7 +330,7 @@
 void PromotionInfo::print_on(outputStream* st) const {
   SpoolBlock* curSpool = NULL;
   size_t i = 0;
-  st->print_cr("start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
+  st->print_cr(" start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
                _firstIndex, _nextIndex);
   for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
        curSpool = curSpool->nextSpoolBlock) {
@@ -350,7 +350,7 @@
     st->print_cr(" free ");
     i++;
   }
-  st->print_cr(SIZE_FORMAT " header spooling blocks", i);
+  st->print_cr("  " SIZE_FORMAT " header spooling blocks", i);
 }
 
 void SpoolBlock::print_on(outputStream* st) const {
--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -2586,9 +2586,6 @@
   double end_time = os::elapsedTime();
   double elapsed_time_ms = (end_time - start) * 1000.0;
   g1h->g1_policy()->record_mark_closure_time(elapsed_time_ms);
-  if (PrintGCDetails) {
-    gclog_or_tty->print_cr("Mark closure took %5.2f ms.", elapsed_time_ms);
-  }
 
   ClearMarksInHRClosure clr(nextMarkBitMap());
   g1h->collection_set_iterate(&clr);
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1044,29 +1044,56 @@
   const size_t capacity_after_gc = capacity();
   const size_t free_after_gc = capacity_after_gc - used_after_gc;
 
+  // This is enforced in arguments.cpp.
+  assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
+         "otherwise the code below doesn't make sense");
+
   // We don't have floating point command-line arguments
-  const double minimum_free_percentage = (double) MinHeapFreeRatio / 100;
+  const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
-  const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
+  const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
 
-  size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage);
-  size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage);
-
-  // Don't shrink less than the initial size.
-  minimum_desired_capacity =
-    MAX2(minimum_desired_capacity,
-         collector_policy()->initial_heap_byte_size());
-  maximum_desired_capacity =
-    MAX2(maximum_desired_capacity,
-         collector_policy()->initial_heap_byte_size());
-
-  // We are failing here because minimum_desired_capacity is
-  assert(used_after_gc <= minimum_desired_capacity, "sanity check");
-  assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check");
+  const size_t min_heap_size = collector_policy()->min_heap_byte_size();
+  const size_t max_heap_size = collector_policy()->max_heap_byte_size();
+
+  // We have to be careful here as these two calculations can overflow
+  // 32-bit size_t's.
+  double used_after_gc_d = (double) used_after_gc;
+  double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
+  double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
+
+  // Let's make sure that they are both under the max heap size, which
+  // by default will make them fit into a size_t.
+  double desired_capacity_upper_bound = (double) max_heap_size;
+  minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
+                                    desired_capacity_upper_bound);
+  maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
+                                    desired_capacity_upper_bound);
+
+  // We can now safely turn them into size_t's.
+  size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
+  size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
+
+  // This assert only makes sense here, before we adjust them
+  // with respect to the min and max heap size.
+  assert(minimum_desired_capacity <= maximum_desired_capacity,
+         err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
+                 "maximum_desired_capacity = "SIZE_FORMAT,
+                 minimum_desired_capacity, maximum_desired_capacity));
+
+  // Should not be greater than the heap max size. No need to adjust
+  // it with respect to the heap min size as it's a lower bound (i.e.,
+  // we'll try to make the capacity larger than it, not smaller).
+  minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
+  // Should not be less than the heap min size. No need to adjust it
+  // with respect to the heap max size as it's an upper bound (i.e.,
+  // we'll try to make the capacity smaller than it, not greater).
+  maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
 
   if (PrintGC && Verbose) {
-    const double free_percentage = ((double)free_after_gc) / capacity();
+    const double free_percentage =
+      (double) free_after_gc / (double) capacity_after_gc;
     gclog_or_tty->print_cr("Computing new size after full GC ");
     gclog_or_tty->print_cr("  "
                            "  minimum_free_percentage: %6.2f",
@@ -1078,45 +1105,47 @@
                            "  capacity: %6.1fK"
                            "  minimum_desired_capacity: %6.1fK"
                            "  maximum_desired_capacity: %6.1fK",
-                           capacity() / (double) K,
-                           minimum_desired_capacity / (double) K,
-                           maximum_desired_capacity / (double) K);
+                           (double) capacity_after_gc / (double) K,
+                           (double) minimum_desired_capacity / (double) K,
+                           (double) maximum_desired_capacity / (double) K);
     gclog_or_tty->print_cr("  "
-                           "   free_after_gc   : %6.1fK"
-                           "   used_after_gc   : %6.1fK",
-                           free_after_gc / (double) K,
-                           used_after_gc / (double) K);
+                           "  free_after_gc: %6.1fK"
+                           "  used_after_gc: %6.1fK",
+                           (double) free_after_gc / (double) K,
+                           (double) used_after_gc / (double) K);
     gclog_or_tty->print_cr("  "
                            "   free_percentage: %6.2f",
                            free_percentage);
   }
-  if (capacity() < minimum_desired_capacity) {
+  if (capacity_after_gc < minimum_desired_capacity) {
     // Don't expand unless it's significant
     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
     expand(expand_bytes);
     if (PrintGC && Verbose) {
-      gclog_or_tty->print_cr("    expanding:"
+      gclog_or_tty->print_cr("  "
+                             "  expanding:"
+                             "  max_heap_size: %6.1fK"
                              "  minimum_desired_capacity: %6.1fK"
                              "  expand_bytes: %6.1fK",
-                             minimum_desired_capacity / (double) K,
-                             expand_bytes / (double) K);
+                             (double) max_heap_size / (double) K,
+                             (double) minimum_desired_capacity / (double) K,
+                             (double) expand_bytes / (double) K);
     }
 
     // No expansion, now see if we want to shrink
-  } else if (capacity() > maximum_desired_capacity) {
+  } else if (capacity_after_gc > maximum_desired_capacity) {
     // Capacity too large, compute shrinking size
     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
     shrink(shrink_bytes);
     if (PrintGC && Verbose) {
       gclog_or_tty->print_cr("  "
                              "  shrinking:"
-                             "  initSize: %.1fK"
-                             "  maximum_desired_capacity: %.1fK",
-                             collector_policy()->initial_heap_byte_size() / (double) K,
-                             maximum_desired_capacity / (double) K);
-      gclog_or_tty->print_cr("  "
-                             "  shrink_bytes: %.1fK",
-                             shrink_bytes / (double) K);
+                             "  min_heap_size: %6.1fK"
+                             "  maximum_desired_capacity: %6.1fK"
+                             "  shrink_bytes: %6.1fK",
+                             (double) min_heap_size / (double) K,
+                             (double) maximum_desired_capacity / (double) K,
+                             (double) shrink_bytes / (double) K);
     }
   }
 }
@@ -2165,9 +2194,12 @@
   }
 }
 
-HeapWord* G1CollectedHeap::allocate_new_tlab(size_t size) {
+HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
+  assert(!isHumongous(word_size),
+         err_msg("a TLAB should not be of humongous size, "
+                 "word_size = "SIZE_FORMAT, word_size));
   bool dummy;
-  return G1CollectedHeap::mem_allocate(size, false, true, &dummy);
+  return G1CollectedHeap::mem_allocate(word_size, false, true, &dummy);
 }
 
 bool G1CollectedHeap::allocs_are_zero_filled() {
@@ -3576,7 +3608,7 @@
   if (!r->evacuation_failed()) {
     r->set_evacuation_failed(true);
     if (G1PrintHeapRegions) {
-      gclog_or_tty->print("evacuation failed in heap region "PTR_FORMAT" "
+      gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
                           "["PTR_FORMAT","PTR_FORMAT")\n",
                           r, r->bottom(), r->end());
     }
@@ -3610,6 +3642,10 @@
 
 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
                                                   size_t word_size) {
+  assert(!isHumongous(word_size),
+         err_msg("we should not be seeing humongous allocation requests "
+                 "during GC, word_size = "SIZE_FORMAT, word_size));
+
   HeapRegion* alloc_region = _gc_alloc_regions[purpose];
   // let the caller handle alloc failure
   if (alloc_region == NULL) return NULL;
@@ -3642,6 +3678,10 @@
                                          HeapRegion*    alloc_region,
                                          bool           par,
                                          size_t         word_size) {
+  assert(!isHumongous(word_size),
+         err_msg("we should not be seeing humongous allocation requests "
+                 "during GC, word_size = "SIZE_FORMAT, word_size));
+
   HeapWord* block = NULL;
   // In the parallel case, a previous thread to obtain the lock may have
   // already assigned a new gc_alloc_region.
@@ -4281,7 +4321,7 @@
   if (evacuation_failed()) {
     remove_self_forwarding_pointers();
     if (PrintGCDetails) {
-      gclog_or_tty->print(" (evacuation failed)");
+      gclog_or_tty->print(" (to-space overflow)");
     } else if (PrintGC) {
       gclog_or_tty->print("--");
     }
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1032,7 +1032,7 @@
   virtual bool supports_tlab_allocation() const;
   virtual size_t tlab_capacity(Thread* thr) const;
   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
-  virtual HeapWord* allocate_new_tlab(size_t size);
+  virtual HeapWord* allocate_new_tlab(size_t word_size);
 
   // Can a compiler initialize a new object without store barriers?
   // This permission only extends from the creation of a new object
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -57,8 +57,9 @@
   assert( SafepointSynchronize::is_at_safepoint() ||
           Heap_lock->owned_by_self(), "pre-condition of the call" );
 
-  if (_cur_alloc_region != NULL) {
-
+  // All humongous allocation requests should go through the slow path in
+  // attempt_allocation_slow().
+  if (!isHumongous(word_size) && _cur_alloc_region != NULL) {
     // If this allocation causes a region to become non empty,
     // then we need to update our free_regions count.
 
@@ -69,13 +70,14 @@
     } else {
       res = _cur_alloc_region->allocate(word_size);
     }
-  }
-  if (res != NULL) {
-    if (!SafepointSynchronize::is_at_safepoint()) {
-      assert( Heap_lock->owned_by_self(), "invariant" );
-      Heap_lock->unlock();
+
+    if (res != NULL) {
+      if (!SafepointSynchronize::is_at_safepoint()) {
+        assert( Heap_lock->owned_by_self(), "invariant" );
+        Heap_lock->unlock();
+      }
+      return res;
     }
-    return res;
   }
   // attempt_allocation_slow will also unlock the heap lock when appropriate.
   return attempt_allocation_slow(word_size, permit_collection_pause);
--- a/src/share/vm/gc_implementation/g1/heapRegion.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/g1/heapRegion.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -790,8 +790,18 @@
   int objs = 0;
   int blocks = 0;
   VerifyLiveClosure vl_cl(g1, use_prev_marking);
+  bool is_humongous = isHumongous();
+  size_t object_num = 0;
   while (p < top()) {
     size_t size = oop(p)->size();
+    if (is_humongous != g1->isHumongous(size)) {
+      gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
+                             SIZE_FORMAT" words) in a %shumongous region",
+                             p, g1->isHumongous(size) ? "" : "non-",
+                             size, is_humongous ? "" : "non-");
+       *failures = true;
+    }
+    object_num += 1;
     if (blocks == BLOCK_SAMPLE_INTERVAL) {
       HeapWord* res = block_start_const(p + (size/2));
       if (p != res) {
@@ -857,6 +867,13 @@
     }
   }
 
+  if (is_humongous && object_num > 1) {
+    gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
+                           "but has "SIZE_FORMAT", objects",
+                           bottom(), end(), object_num);
+    *failures = true;
+  }
+
   if (p != top()) {
     gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
                            "does not match top "PTR_FORMAT, p, top());
--- a/src/share/vm/gc_implementation/includeDB_gc_concurrentMarkSweep	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/gc_implementation/includeDB_gc_concurrentMarkSweep	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2004, 2009, Oracle and/or its affiliates. All rights reserved.
+// Copyright (c) 2004, 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
@@ -34,6 +34,8 @@
 binaryTreeDictionary.hpp                freeBlockDictionary.hpp
 binaryTreeDictionary.hpp                freeList.hpp
 
+blockOffsetTable.inline.hpp             concurrentMarkSweepGeneration.hpp
+
 cmsAdaptiveSizePolicy.cpp		cmsAdaptiveSizePolicy.hpp
 cmsAdaptiveSizePolicy.cpp		defNewGeneration.hpp
 cmsAdaptiveSizePolicy.cpp		gcStats.hpp
@@ -85,7 +87,7 @@
 cmsOopClosures.inline.hpp               cmsOopClosures.hpp
 cmsOopClosures.inline.hpp               concurrentMarkSweepGeneration.hpp
 
-cmsPermGen.cpp                          blockOffsetTable.hpp
+cmsPermGen.cpp                          blockOffsetTable.inline.hpp
 cmsPermGen.cpp                          cSpaceCounters.hpp
 cmsPermGen.cpp                          cmsPermGen.hpp
 cmsPermGen.cpp                          collectedHeap.inline.hpp
@@ -121,6 +123,7 @@
 compactibleFreeListSpace.cpp            vmThread.hpp
 
 compactibleFreeListSpace.hpp            binaryTreeDictionary.hpp
+compactibleFreeListSpace.hpp            blockOffsetTable.inline.hpp
 compactibleFreeListSpace.hpp            freeList.hpp
 compactibleFreeListSpace.hpp            promotionInfo.hpp
 compactibleFreeListSpace.hpp            space.hpp
--- a/src/share/vm/includeDB_core	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/includeDB_core	Thu Aug 19 14:08:58 2010 -0400
@@ -225,7 +225,6 @@
 arrayOop.cpp                            symbolOop.hpp
 
 arrayOop.hpp                            oop.hpp
-arrayOop.hpp                            universe.hpp
 arrayOop.hpp                            universe.inline.hpp
 
 assembler.cpp                           assembler.hpp
@@ -236,7 +235,6 @@
 assembler.cpp                           os.hpp
 
 assembler.hpp                           allocation.hpp
-assembler.hpp                           allocation.inline.hpp
 assembler.hpp                           debug.hpp
 assembler.hpp                           growableArray.hpp
 assembler.hpp                           oopRecorder.hpp
@@ -330,7 +328,7 @@
 blockOffsetTable.cpp                    iterator.hpp
 blockOffsetTable.cpp                    java.hpp
 blockOffsetTable.cpp                    oop.inline.hpp
-blockOffsetTable.cpp                    space.hpp
+blockOffsetTable.cpp                    space.inline.hpp
 blockOffsetTable.cpp                    universe.hpp
 
 blockOffsetTable.hpp                    globalDefinitions.hpp
@@ -338,6 +336,7 @@
 blockOffsetTable.hpp                    virtualspace.hpp
 
 blockOffsetTable.inline.hpp             blockOffsetTable.hpp
+blockOffsetTable.inline.hpp             safepoint.hpp
 blockOffsetTable.inline.hpp             space.hpp
 
 bytecode.cpp                            bytecode.hpp
@@ -1807,7 +1806,7 @@
 generateOopMap.hpp                      universe.inline.hpp
 
 generation.cpp                          allocation.inline.hpp
-generation.cpp                          blockOffsetTable.hpp
+generation.cpp                          blockOffsetTable.inline.hpp
 generation.cpp                          cardTableRS.hpp
 generation.cpp                          collectedHeap.inline.hpp
 generation.cpp                          copy.hpp
@@ -3436,7 +3435,7 @@
 perfMemory_<os_family>.cpp              resourceArea.hpp
 perfMemory_<os_family>.cpp              vmSymbols.hpp
 
-permGen.cpp                             blockOffsetTable.hpp
+permGen.cpp                             blockOffsetTable.inline.hpp
 permGen.cpp                             cSpaceCounters.hpp
 permGen.cpp                             collectedHeap.inline.hpp
 permGen.cpp                             compactPermGen.hpp
@@ -3805,7 +3804,7 @@
 sizes.hpp                               allocation.hpp
 sizes.hpp                               globalDefinitions.hpp
 
-space.cpp                               blockOffsetTable.hpp
+space.cpp                               blockOffsetTable.inline.hpp
 space.cpp                               copy.hpp
 space.cpp                               defNewGeneration.hpp
 space.cpp                               genCollectedHeap.hpp
@@ -3835,7 +3834,6 @@
 space.hpp                               watermark.hpp
 space.hpp                               workgroup.hpp
 
-space.inline.hpp                        blockOffsetTable.inline.hpp
 space.inline.hpp                        collectedHeap.hpp
 space.inline.hpp                        safepoint.hpp
 space.inline.hpp                        space.hpp
--- a/src/share/vm/memory/allocation.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/memory/allocation.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -58,7 +58,7 @@
 void ResourceObj::operator delete(void* p) {
   assert(((ResourceObj *)p)->allocated_on_C_heap(),
          "delete only allowed for C_HEAP objects");
-  DEBUG_ONLY(((ResourceObj *)p)->_allocation = badHeapOopVal;)
+  DEBUG_ONLY(((ResourceObj *)p)->_allocation = (uintptr_t) badHeapOopVal;)
   FreeHeap(p);
 }
 
@@ -104,7 +104,7 @@
 ResourceObj::~ResourceObj() {
     // allocated_on_C_heap() also checks that encoded (in _allocation) address == this.
     if (!allocated_on_C_heap()) {  // ResourceObj::delete() zaps _allocation for C_heap.
-      _allocation = badHeapOopVal; // zap type
+      _allocation = (uintptr_t) badHeapOopVal; // zap type
     }
 }
 #endif // ASSERT
--- a/src/share/vm/memory/blockOffsetTable.cpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/memory/blockOffsetTable.cpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -103,13 +103,13 @@
 //////////////////////////////////////////////////////////////////////
 
 BlockOffsetArray::BlockOffsetArray(BlockOffsetSharedArray* array,
-                                   MemRegion mr, bool init_to_zero) :
+                                   MemRegion mr, bool init_to_zero_) :
   BlockOffsetTable(mr.start(), mr.end()),
-  _array(array),
-  _init_to_zero(init_to_zero)
+  _array(array)
 {
   assert(_bottom <= _end, "arguments out of order");
-  if (!_init_to_zero) {
+  set_init_to_zero(init_to_zero_);
+  if (!init_to_zero_) {
     // initialize cards to point back to mr.start()
     set_remainder_to_point_to_start(mr.start() + N_words, mr.end());
     _array->set_offset_array(0, 0);  // set first card to 0
@@ -121,8 +121,9 @@
 // a right-open interval: [start, end)
 void
 BlockOffsetArray::
-set_remainder_to_point_to_start(HeapWord* start, HeapWord* end) {
+set_remainder_to_point_to_start(HeapWord* start, HeapWord* end, bool reducing) {
 
+  check_reducing_assertion(reducing);
   if (start >= end) {
     // The start address is equal to the end address (or to
     // the right of the end address) so there are not cards
@@ -167,7 +168,7 @@
   size_t end_card = _array->index_for(end-1);
   assert(start ==_array->address_for_index(start_card), "Precondition");
   assert(end ==_array->address_for_index(end_card)+N_words, "Precondition");
-  set_remainder_to_point_to_start_incl(start_card, end_card); // closed interval
+  set_remainder_to_point_to_start_incl(start_card, end_card, reducing); // closed interval
 }
 
 
@@ -175,7 +176,9 @@
 // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start()
 // above.
 void
-BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card) {
+BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card, bool reducing) {
+
+  check_reducing_assertion(reducing);
   if (start_card > end_card) {
     return;
   }
@@ -191,11 +194,11 @@
     size_t reach = start_card - 1 + (power_to_cards_back(i+1) - 1);
     offset = N_words + i;
     if (reach >= end_card) {
-      _array->set_offset_array(start_card_for_region, end_card, offset);
+      _array->set_offset_array(start_card_for_region, end_card, offset, reducing);
       start_card_for_region = reach + 1;
       break;
     }
-    _array->set_offset_array(start_card_for_region, reach, offset);
+    _array->set_offset_array(start_card_for_region, reach, offset, reducing);
     start_card_for_region = reach + 1;
   }
   assert(start_card_for_region > end_card, "Sanity check");
@@ -211,8 +214,10 @@
     return;
   }
   guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card");
+  u_char last_entry = N_words;
   for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) {
     u_char entry = _array->offset_array(c);
+    guarantee(entry >= last_entry, "Monotonicity");
     if (c - start_card > power_to_cards_back(1)) {
       guarantee(entry > N_words, "Should be in logarithmic region");
     }
@@ -220,11 +225,13 @@
     size_t landing_card = c - backskip;
     guarantee(landing_card >= (start_card - 1), "Inv");
     if (landing_card >= start_card) {
-      guarantee(_array->offset_array(landing_card) <= entry, "monotonicity");
+      guarantee(_array->offset_array(landing_card) <= entry, "Monotonicity");
     } else {
-      guarantee(landing_card == start_card - 1, "Tautology");
+      guarantee(landing_card == (start_card - 1), "Tautology");
+      // Note that N_words is the maximum offset value
       guarantee(_array->offset_array(landing_card) <= N_words, "Offset value");
     }
+    last_entry = entry;  // remember for monotonicity test
   }
 }
 
@@ -243,7 +250,7 @@
 void
 BlockOffsetArray::do_block_internal(HeapWord* blk_start,
                                     HeapWord* blk_end,
-                                    Action action) {
+                                    Action action, bool reducing) {
   assert(Universe::heap()->is_in_reserved(blk_start),
          "reference must be into the heap");
   assert(Universe::heap()->is_in_reserved(blk_end-1),
@@ -275,18 +282,18 @@
     switch (action) {
       case Action_mark: {
         if (init_to_zero()) {
-          _array->set_offset_array(start_index, boundary, blk_start);
+          _array->set_offset_array(start_index, boundary, blk_start, reducing);
           break;
         } // Else fall through to the next case
       }
       case Action_single: {
-        _array->set_offset_array(start_index, boundary, blk_start);
+        _array->set_offset_array(start_index, boundary, blk_start, reducing);
         // We have finished marking the "offset card". We need to now
         // mark the subsequent cards that this blk spans.
         if (start_index < end_index) {
           HeapWord* rem_st = _array->address_for_index(start_index) + N_words;
           HeapWord* rem_end = _array->address_for_index(end_index) + N_words;
-          set_remainder_to_point_to_start(rem_st, rem_end);
+          set_remainder_to_point_to_start(rem_st, rem_end, reducing);
         }
         break;
       }
@@ -395,7 +402,7 @@
   // Indices for starts of prefix block and suffix block.
   size_t pref_index = _array->index_for(pref_addr);
   if (_array->address_for_index(pref_index) != pref_addr) {
-    // pref_addr deos not begin pref_index
+    // pref_addr does not begin pref_index
     pref_index++;
   }
 
@@ -430,18 +437,18 @@
   if (num_suff_cards > 0) {
     HeapWord* boundary = _array->address_for_index(suff_index);
     // Set the offset card for suffix block
-    _array->set_offset_array(suff_index, boundary, suff_addr);
+    _array->set_offset_array(suff_index, boundary, suff_addr, true /* reducing */);
     // Change any further cards that need changing in the suffix
     if (num_pref_cards > 0) {
       if (num_pref_cards >= num_suff_cards) {
         // Unilaterally fix all of the suffix cards: closed card
         // index interval in args below.
-        set_remainder_to_point_to_start_incl(suff_index + 1, end_index - 1);
+        set_remainder_to_point_to_start_incl(suff_index + 1, end_index - 1, true /* reducing */);
       } else {
         // Unilaterally fix the first (num_pref_cards - 1) following
         // the "offset card" in the suffix block.
         set_remainder_to_point_to_start_incl(suff_index + 1,
-          suff_index + num_pref_cards - 1);
+          suff_index + num_pref_cards - 1, true /* reducing */);
         // Fix the appropriate cards in the remainder of the
         // suffix block -- these are the last num_pref_cards
         // cards in each power block of the "new" range plumbed
@@ -461,7 +468,7 @@
             // is non-null.
             if (left_index <= right_index) {
               _array->set_offset_array(left_index, right_index,
-                                     N_words + i - 1);
+                                     N_words + i - 1, true /* reducing */);
             } else {
               more = false; // we are done
             }
@@ -482,7 +489,7 @@
             more  = false;
           }
           assert(left_index <= right_index, "Error");
-          _array->set_offset_array(left_index, right_index, N_words + i - 1);
+          _array->set_offset_array(left_index, right_index, N_words + i - 1, true /* reducing */);
           i++;
         }
       }
@@ -501,14 +508,13 @@
 // any cards subsequent to the first one.
 void
 BlockOffsetArrayNonContigSpace::mark_block(HeapWord* blk_start,
-                                           HeapWord* blk_end) {
-  do_block_internal(blk_start, blk_end, Action_mark);
+                                           HeapWord* blk_end, bool reducing) {
+  do_block_internal(blk_start, blk_end, Action_mark, reducing);
 }
 
 HeapWord* BlockOffsetArrayNonContigSpace::block_start_unsafe(
   const void* addr) const {
   assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
-
   assert(_bottom <= addr && addr < _end,
          "addr must be covered by this Array");
   // Must read this exactly once because it can be modified by parallel
@@ -542,9 +548,10 @@
     debug_only(HeapWord* last = q);   // for debugging
     q = n;
     n += _sp->block_size(n);
+    assert(n > q, err_msg("Looping at: " INTPTR_FORMAT, n));
   }
-  assert(q <= addr, "wrong order for current and arg");
-  assert(addr <= n, "wrong order for arg and next");
+  assert(q <= addr, err_msg("wrong order for current (" INTPTR_FORMAT ") <= arg (" INTPTR_FORMAT ")", q, addr));
+  assert(addr <= n, err_msg("wrong order for arg (" INTPTR_FORMAT ") <= next (" INTPTR_FORMAT ")", addr, n));
   return q;
 }
 
@@ -727,9 +734,8 @@
   _next_offset_index = end_index + 1;
   // Calculate _next_offset_threshold this way because end_index
   // may be the last valid index in the covered region.
-  _next_offset_threshold = _array->address_for_index(end_index) +
-    N_words;
-  assert(_next_offset_threshold >= blk_end, "Incorrent offset threshold");
+  _next_offset_threshold = _array->address_for_index(end_index) + N_words;
+  assert(_next_offset_threshold >= blk_end, "Incorrect offset threshold");
 
 #ifdef ASSERT
   // The offset can be 0 if the block starts on a boundary.  That
--- a/src/share/vm/memory/blockOffsetTable.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/memory/blockOffsetTable.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -107,6 +107,8 @@
     N_words = 1 << LogN_words
   };
 
+  bool _init_to_zero;
+
   // The reserved region covered by the shared array.
   MemRegion _reserved;
 
@@ -125,17 +127,28 @@
     assert(index < _vs.committed_size(), "index out of range");
     return _offset_array[index];
   }
-  void set_offset_array(size_t index, u_char offset) {
+  // An assertion-checking helper method for the set_offset_array() methods below.
+  void check_reducing_assertion(bool reducing);
+
+  void set_offset_array(size_t index, u_char offset, bool reducing = false) {
+    check_reducing_assertion(reducing);
     assert(index < _vs.committed_size(), "index out of range");
+    assert(!reducing || _offset_array[index] >= offset, "Not reducing");
     _offset_array[index] = offset;
   }
-  void set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
+
+  void set_offset_array(size_t index, HeapWord* high, HeapWord* low, bool reducing = false) {
+    check_reducing_assertion(reducing);
     assert(index < _vs.committed_size(), "index out of range");
     assert(high >= low, "addresses out of order");
     assert(pointer_delta(high, low) <= N_words, "offset too large");
+    assert(!reducing || _offset_array[index] >=  (u_char)pointer_delta(high, low),
+           "Not reducing");
     _offset_array[index] = (u_char)pointer_delta(high, low);
   }
-  void set_offset_array(HeapWord* left, HeapWord* right, u_char offset) {
+
+  void set_offset_array(HeapWord* left, HeapWord* right, u_char offset, bool reducing = false) {
+    check_reducing_assertion(reducing);
     assert(index_for(right - 1) < _vs.committed_size(),
            "right address out of range");
     assert(left  < right, "Heap addresses out of order");
@@ -150,12 +163,14 @@
       size_t i = index_for(left);
       const size_t end = i + num_cards;
       for (; i < end; i++) {
+        assert(!reducing || _offset_array[i] >= offset, "Not reducing");
         _offset_array[i] = offset;
       }
     }
   }
 
-  void set_offset_array(size_t left, size_t right, u_char offset) {
+  void set_offset_array(size_t left, size_t right, u_char offset, bool reducing = false) {
+    check_reducing_assertion(reducing);
     assert(right < _vs.committed_size(), "right address out of range");
     assert(left  <= right, "indexes out of order");
     size_t num_cards = right - left + 1;
@@ -169,6 +184,7 @@
       size_t i = left;
       const size_t end = i + num_cards;
       for (; i < end; i++) {
+        assert(!reducing || _offset_array[i] >= offset, "Not reducing");
         _offset_array[i] = offset;
       }
     }
@@ -212,6 +228,11 @@
 
   void set_bottom(HeapWord* new_bottom);
 
+  // Whether entries should be initialized to zero. Used currently only for
+  // error checking.
+  void set_init_to_zero(bool val) { _init_to_zero = val; }
+  bool init_to_zero() { return _init_to_zero; }
+
   // Updates all the BlockOffsetArray's sharing this shared array to
   // reflect the current "top"'s of their spaces.
   void update_offset_arrays();   // Not yet implemented!
@@ -285,17 +306,23 @@
   // initialized to point backwards to the beginning of the covered region.
   bool _init_to_zero;
 
+  // An assertion-checking helper method for the set_remainder*() methods below.
+  void check_reducing_assertion(bool reducing) { _array->check_reducing_assertion(reducing); }
+
   // Sets the entries
   // corresponding to the cards starting at "start" and ending at "end"
   // to point back to the card before "start": the interval [start, end)
-  // is right-open.
-  void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end);
+  // is right-open. The last parameter, reducing, indicates whether the
+  // updates to individual entries always reduce the entry from a higher
+  // to a lower value. (For example this would hold true during a temporal
+  // regime during which only block splits were updating the BOT.
+  void set_remainder_to_point_to_start(HeapWord* start, HeapWord* end, bool reducing = false);
   // Same as above, except that the args here are a card _index_ interval
   // that is closed: [start_index, end_index]
-  void set_remainder_to_point_to_start_incl(size_t start, size_t end);
+  void set_remainder_to_point_to_start_incl(size_t start, size_t end, bool reducing = false);
 
   // A helper function for BOT adjustment/verification work
-  void do_block_internal(HeapWord* blk_start, HeapWord* blk_end, Action action);
+  void do_block_internal(HeapWord* blk_start, HeapWord* blk_end, Action action, bool reducing = false);
 
  public:
   // The space may not have its bottom and top set yet, which is why the
@@ -303,7 +330,7 @@
   // elements of the array are initialized to zero.  Otherwise, they are
   // initialized to point backwards to the beginning.
   BlockOffsetArray(BlockOffsetSharedArray* array, MemRegion mr,
-                   bool init_to_zero);
+                   bool init_to_zero_);
 
   // Note: this ought to be part of the constructor, but that would require
   // "this" to be passed as a parameter to a member constructor for
@@ -358,6 +385,12 @@
   // If true, initialize array slots with no allocated blocks to zero.
   // Otherwise, make them point back to the front.
   bool init_to_zero() { return _init_to_zero; }
+  // Corresponding setter
+  void set_init_to_zero(bool val) {
+    _init_to_zero = val;
+    assert(_array != NULL, "_array should be non-NULL");
+    _array->set_init_to_zero(val);
+  }
 
   // Debugging
   // Return the index of the last entry in the "active" region.
@@ -424,16 +457,16 @@
   // of BOT is touched. It is assumed (and verified in the
   // non-product VM) that the remaining cards of the block
   // are correct.
-  void mark_block(HeapWord* blk_start, HeapWord* blk_end);
-  void mark_block(HeapWord* blk, size_t size) {
-    mark_block(blk, blk + size);
+  void mark_block(HeapWord* blk_start, HeapWord* blk_end, bool reducing = false);
+  void mark_block(HeapWord* blk, size_t size, bool reducing = false) {
+    mark_block(blk, blk + size, reducing);
   }
 
   // Adjust _unallocated_block to indicate that a particular
   // block has been newly allocated or freed. It is assumed (and
   // verified in the non-product VM) that the BOT is correct for
   // the given block.
-  void allocated(HeapWord* blk_start, HeapWord* blk_end) {
+  void allocated(HeapWord* blk_start, HeapWord* blk_end, bool reducing = false) {
     // Verify that the BOT shows [blk, blk + blk_size) to be one block.
     verify_single_block(blk_start, blk_end);
     if (BlockOffsetArrayUseUnallocatedBlock) {
@@ -441,14 +474,12 @@
     }
   }
 
-  void allocated(HeapWord* blk, size_t size) {
-    allocated(blk, blk + size);
+  void allocated(HeapWord* blk, size_t size, bool reducing = false) {
+    allocated(blk, blk + size, reducing);
   }
 
   void freed(HeapWord* blk_start, HeapWord* blk_end);
-  void freed(HeapWord* blk, size_t size) {
-    freed(blk, blk + size);
-  }
+  void freed(HeapWord* blk, size_t size);
 
   HeapWord* block_start_unsafe(const void* addr) const;
 
@@ -456,7 +487,6 @@
   // start of the block that contains the given address.
   HeapWord* block_start_careful(const void* addr) const;
 
-
   // Verification & debugging: ensure that the offset table reflects
   // the fact that the block [blk_start, blk_end) or [blk, blk + size)
   // is a single block of storage. NOTE: can't const this because of
--- a/src/share/vm/memory/blockOffsetTable.inline.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/memory/blockOffsetTable.inline.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2002, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -55,10 +55,22 @@
   return result;
 }
 
+inline void BlockOffsetSharedArray::check_reducing_assertion(bool reducing) {
+    assert(reducing || !SafepointSynchronize::is_at_safepoint() || init_to_zero() ||
+           Thread::current()->is_VM_thread() ||
+           Thread::current()->is_ConcurrentGC_thread() ||
+           ((!Thread::current()->is_ConcurrentGC_thread()) &&
+            ParGCRareEvent_lock->owned_by_self()), "Crack");
+}
 
 //////////////////////////////////////////////////////////////////////////
 // BlockOffsetArrayNonContigSpace inlines
 //////////////////////////////////////////////////////////////////////////
+inline void BlockOffsetArrayNonContigSpace::freed(HeapWord* blk,
+                                                  size_t size) {
+  freed(blk, blk + size);
+}
+
 inline void BlockOffsetArrayNonContigSpace::freed(HeapWord* blk_start,
                                                   HeapWord* blk_end) {
   // Verify that the BOT shows [blk_start, blk_end) to be one block.
--- a/src/share/vm/runtime/globals.hpp	Tue Aug 17 22:52:50 2010 -0700
+++ b/src/share/vm/runtime/globals.hpp	Thu Aug 19 14:08:58 2010 -0400
@@ -1712,7 +1712,7 @@
   develop(bool, VerifyBlockOffsetArray, false,                              \
           "Do (expensive!) block offset array verification")                \
                                                                             \
-  product(bool, BlockOffsetArrayUseUnallocatedBlock, trueInDebug,           \
+  product(bool, BlockOffsetArrayUseUnallocatedBlock, false,                 \
           "Maintain _unallocated_block in BlockOffsetArray"                 \
           " (currently applicable only to CMS collector)")                  \
                                                                             \