jdk8-mips64-public/hotspot: src/share/vm/oops/objArrayOop.hpp@e1162778c1c8

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

     1 /*

     2  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    25 #ifndef SHARE_VM_OOPS_OBJARRAYOOP_HPP

    26 #define SHARE_VM_OOPS_OBJARRAYOOP_HPP

    28 #include "oops/arrayOop.hpp"

    30 // An objArrayOop is an array containing oops.

    31 // Evaluating "String arg[10]" will create an objArrayOop.

    33 class objArrayOopDesc : public arrayOopDesc {

    34   friend class objArrayKlass;

    35   friend class Runtime1;

    36   friend class psPromotionManager;

    37   friend class CSMarkOopClosure;

    38   friend class G1ParScanPartialArrayClosure;

    40   template <class T> T* obj_at_addr(int index) const {

    41     assert(is_within_bounds(index), "index out of bounds");

    42     return &((T*)base())[index];

    43   }

    45 private:

    46   // Give size of objArrayOop in HeapWords minus the header

    47   static int array_size(int length) {

    48     const int OopsPerHeapWord = HeapWordSize/heapOopSize;

    49     assert(OopsPerHeapWord >= 1 && (HeapWordSize % heapOopSize == 0),

    50            "Else the following (new) computation would be in error");

    51 #ifdef ASSERT

    52     // The old code is left in for sanity-checking; it'll

    53     // go away pretty soon. XXX

    54     // Without UseCompressedOops, this is simply:

    55     // oop->length() * HeapWordsPerOop;

    56     // With narrowOops, HeapWordsPerOop is 1/2 or equal 0 as an integer.

    57     // The oop elements are aligned up to wordSize

    58     const int HeapWordsPerOop = heapOopSize/HeapWordSize;

    59     int old_res;

    60     if (HeapWordsPerOop > 0) {

    61       old_res = length * HeapWordsPerOop;

    62     } else {

    63       old_res = align_size_up(length, OopsPerHeapWord)/OopsPerHeapWord;

    64     }

    65 #endif  // ASSERT

    66     int res = ((uint)length + OopsPerHeapWord - 1)/OopsPerHeapWord;

    67     assert(res == old_res, "Inconsistency between old and new.");

    68     return res;

    69   }

    71  public:

    72   // Returns the offset of the first element.

    73   static int base_offset_in_bytes() {

    74     return arrayOopDesc::base_offset_in_bytes(T_OBJECT);

    75   }

    77   // base is the address following the header.

    78   HeapWord* base() const      { return (HeapWord*) arrayOopDesc::base(T_OBJECT); }

    80   // Accessing

    81   oop obj_at(int index) const {

    82     // With UseCompressedOops decode the narrow oop in the objArray to an

    83     // uncompressed oop.  Otherwise this is simply a "*" operator.

    84     if (UseCompressedOops) {

    85       return load_decode_heap_oop(obj_at_addr<narrowOop>(index));

    86     } else {

    87       return load_decode_heap_oop(obj_at_addr<oop>(index));

    88     }

    89   }

    91   void obj_at_put(int index, oop value) {

    92     if (UseCompressedOops) {

    93       oop_store(obj_at_addr<narrowOop>(index), value);

    94     } else {

    95       oop_store(obj_at_addr<oop>(index), value);

    96     }

    97   }

    98   // Sizing

    99   static int header_size()    { return arrayOopDesc::header_size(T_OBJECT); }

   100   int object_size()           { return object_size(length()); }

   102   static int object_size(int length) {

   103     // This returns the object size in HeapWords.

   104     uint asz = array_size(length);

   105     uint osz = align_object_size(header_size() + asz);

   106     assert(osz >= asz,   "no overflow");

   107     assert((int)osz > 0, "no overflow");

   108     return (int)osz;

   109   }

   111   // special iterators for index ranges, returns size of object

   112 #define ObjArrayOop_OOP_ITERATE_DECL(OopClosureType, nv_suffix)     \

   113   int oop_iterate_range(OopClosureType* blk, int start, int end);

   115   ALL_OOP_OOP_ITERATE_CLOSURES_1(ObjArrayOop_OOP_ITERATE_DECL)

   116   ALL_OOP_OOP_ITERATE_CLOSURES_2(ObjArrayOop_OOP_ITERATE_DECL)

   117 };

   119 #endif // SHARE_VM_OOPS_OBJARRAYOOP_HPP

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/oops/objArrayOop.hpp@e1162778c1c8

src/share/vm/oops/objArrayOop.hpp