jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp@e1162778c1c8 (annotated)

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp@e1162778c1c8 (annotated)

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp

Thu, 07 Apr 2011 09:53:20 -0700

author: johnc
date: Thu, 07 Apr 2011 09:53:20 -0700
changeset 2781: e1162778c1c8
parent 2314: f95d63e2154a
child 4037: da91efe96a93
permissions: -rw-r--r--

7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes

 /*
  * 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
  * 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
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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_INLINE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_INLINE_HPP
 #include "gc_implementation/g1/g1BlockOffsetTable.hpp"
 #include "memory/space.hpp"
 inline HeapWord* G1BlockOffsetTable::block_start(const void* addr) {
   if (addr >= _bottom && addr < _end) {
     return block_start_unsafe(addr);
   } else {
     return NULL;
   }
 }
 inline HeapWord*
 G1BlockOffsetTable::block_start_const(const void* addr) const {
   if (addr >= _bottom && addr < _end) {
     return block_start_unsafe_const(addr);
   } else {
     return NULL;
   }
 }
 inline size_t G1BlockOffsetSharedArray::index_for(const void* p) const {
   char* pc = (char*)p;
   assert(pc >= (char*)_reserved.start() &&
          pc <  (char*)_reserved.end(),
          "p not in range.");
   size_t delta = pointer_delta(pc, _reserved.start(), sizeof(char));
   size_t result = delta >> LogN;
   assert(result < _vs.committed_size(), "bad index from address");
   return result;
 }
 inline HeapWord*
 G1BlockOffsetSharedArray::address_for_index(size_t index) const {
   assert(index < _vs.committed_size(), "bad index");
   HeapWord* result = _reserved.start() + (index << LogN_words);
   assert(result >= _reserved.start() && result < _reserved.end(),
          "bad address from index");
   return result;
 }
 inline HeapWord*
 G1BlockOffsetArray::block_at_or_preceding(const void* addr,
                                           bool has_max_index,
                                           size_t max_index) const {
   assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
   size_t index = _array->index_for(addr);
   // We must make sure that the offset table entry we use is valid.  If
   // "addr" is past the end, start at the last known one and go forward.
   if (has_max_index) {
     index = MIN2(index, max_index);
   }
   HeapWord* q = _array->address_for_index(index);
   uint offset = _array->offset_array(index);  // Extend u_char to uint.
   while (offset >= N_words) {
     // The excess of the offset from N_words indicates a power of Base
     // to go back by.
     size_t n_cards_back = BlockOffsetArray::entry_to_cards_back(offset);
     q -= (N_words * n_cards_back);
     assert(q >= _sp->bottom(), "Went below bottom!");
     index -= n_cards_back;
     offset = _array->offset_array(index);
   }
   assert(offset < N_words, "offset too large");
   q -= offset;
   return q;
 }
 inline HeapWord*
 G1BlockOffsetArray::
 forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n,
                                        const void* addr) const {
   if (csp() != NULL) {
     if (addr >= csp()->top()) return csp()->top();
     while (n <= addr) {
       q = n;
       oop obj = oop(q);
       if (obj->klass_or_null() == NULL) return q;
       n += obj->size();
     }
   } else {
     while (n <= addr) {
       q = n;
       oop obj = oop(q);
       if (obj->klass_or_null() == NULL) return q;
       n += _sp->block_size(q);
     }
   }
   assert(q <= n, "wrong order for q and addr");
   assert(addr < n, "wrong order for addr and n");
   return q;
 }
 inline HeapWord*
 G1BlockOffsetArray::forward_to_block_containing_addr(HeapWord* q,
                                                      const void* addr) {
   if (oop(q)->klass_or_null() == NULL) return q;
   HeapWord* n = q + _sp->block_size(q);
   // In the normal case, where the query "addr" is a card boundary, and the
   // offset table chunks are the same size as cards, the block starting at
   // "q" will contain addr, so the test below will fail, and we'll fall
   // through quickly.
   if (n <= addr) {
     q = forward_to_block_containing_addr_slow(q, n, addr);
   }
   assert(q <= addr, "wrong order for current and arg");
   return q;
 }
 //////////////////////////////////////////////////////////////////////////
 // BlockOffsetArrayNonContigSpace inlines
 //////////////////////////////////////////////////////////////////////////
 inline void G1BlockOffsetArray::freed(HeapWord* blk_start, HeapWord* blk_end) {
   // Verify that the BOT shows [blk_start, blk_end) to be one block.
   verify_single_block(blk_start, blk_end);
   // adjust _unallocated_block upward or downward
   // as appropriate
   if (BlockOffsetArrayUseUnallocatedBlock) {
     assert(_unallocated_block <= _end,
            "Inconsistent value for _unallocated_block");
     if (blk_end >= _unallocated_block && blk_start <= _unallocated_block) {
       // CMS-specific note: a block abutting _unallocated_block to
       // its left is being freed, a new block is being added or
       // we are resetting following a compaction
       _unallocated_block = blk_start;
     }
   }
 }
 inline void G1BlockOffsetArray::freed(HeapWord* blk, size_t size) {
   freed(blk, blk + size);
 }
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_INLINE_HPP

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src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp@e1162778c1c8 (annotated)

src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp