src/hotspot/share/gc/shared/accessBarrierSupport.cpp
author pliden
Fri, 02 Nov 2018 07:58:22 +0100
changeset 52383 71564a544d4c
parent 47998 fb0275c320a0
permissions -rw-r--r--
8212184: Incorrect oop ref strength used for referents in FinalReference Reviewed-by: eosterlund, kbarrett
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
47998
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     1
/*
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     2
 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     3
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     4
 *
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     5
 * This code is free software; you can redistribute it and/or modify it
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     6
 * under the terms of the GNU General Public License version 2 only, as
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     7
 * published by the Free Software Foundation.
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     8
 *
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
     9
 * This code is distributed in the hope that it will be useful, but WITHOUT
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    10
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    11
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    12
 * version 2 for more details (a copy is included in the LICENSE file that
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    13
 * accompanied this code).
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    14
 *
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    15
 * You should have received a copy of the GNU General Public License version
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    16
 * 2 along with this work; if not, write to the Free Software Foundation,
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    17
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    18
 *
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    19
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    20
 * or visit www.oracle.com if you need additional information or have any
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    21
 * questions.
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    22
 *
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    23
 */
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    24
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    25
#include "precompiled.hpp"
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    26
#include "classfile/javaClasses.inline.hpp"
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    27
#include "gc/shared/accessBarrierSupport.inline.hpp"
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    28
#include "oops/access.hpp"
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    29
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    30
DecoratorSet AccessBarrierSupport::resolve_unknown_oop_ref_strength(DecoratorSet decorators, oop base, ptrdiff_t offset) {
52383
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    31
  // Note that the referent in a FinalReference is technically not strong.
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    32
  // However, it always behaves like one in practice. The two cases are:
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    33
  //   1) A mutator calls Reference.get(). However, a mutator can only ever
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    34
  //      see inactive FinalReferences, whose referents really are strong.
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    35
  //   2) A GC heap walking operation. In this case the GC can see active
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    36
  //      FinalReferences, but the GC always wants to follow the referent
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    37
  //      as if it was strong.
47998
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    38
  DecoratorSet ds = decorators & ~ON_UNKNOWN_OOP_REF;
52383
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    39
  if (!java_lang_ref_Reference::is_referent_field(base, offset) ||
71564a544d4c 8212184: Incorrect oop ref strength used for referents in FinalReference
pliden
parents: 47998
diff changeset
    40
      java_lang_ref_Reference::is_final(base)) {
47998
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    41
    ds |= ON_STRONG_OOP_REF;
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    42
  } else if (java_lang_ref_Reference::is_phantom(base)) {
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    43
    ds |= ON_PHANTOM_OOP_REF;
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    44
  } else {
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    45
    ds |= ON_WEAK_OOP_REF;
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    46
  }
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    47
  return ds;
fb0275c320a0 8189871: Refactor GC barriers to use declarative semantics
eosterlund
parents:
diff changeset
    48
}