jdk8-mips64-public/hotspot: src/share/vm/memory/barrierSet.hpp@2c022e432e10 (annotated)

src/share/vm/memory/barrierSet.hpp@2c022e432e10 (annotated)

src/share/vm/memory/barrierSet.hpp

Fri, 20 Sep 2013 10:53:28 +0200

author: stefank
date: Fri, 20 Sep 2013 10:53:28 +0200
changeset 5769: 2c022e432e10
parent 4037: da91efe96a93
child 6493: 3205e78d8193
permissions: -rw-r--r--

8024974: Incorrect use of GC_locker::is_active()
Summary: SymbolTable and StringTable can make calls to GC_locker::is_active() outside a safepoint. This isn't safe because the GC_locker active state (lock count) is only updated at a safepoint and only remains valid as long as _needs_gc is true. However, outside a safepoint_needs_gc can change to false at any time, which makes it impossible to do a correct call to is_active() in that context. In this case these calls can just be removed since the input argument to basic_add() should never be on the heap and so there's no need to check the GC_locker state. This change also adjusts the assert() in is_active() to makes sure all calls to this function are always done under a safepoint.
Reviewed-by: brutisso, dcubed
Contributed-by: per.liden@oracle.com

 /*
  * Copyright (c) 2000, 2012, 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_MEMORY_BARRIERSET_HPP
 #define SHARE_VM_MEMORY_BARRIERSET_HPP
 #include "memory/memRegion.hpp"
 #include "oops/oopsHierarchy.hpp"
 // This class provides the interface between a barrier implementation and
 // the rest of the system.
 class BarrierSet: public CHeapObj<mtGC> {
   friend class VMStructs;
 public:
   enum Name {
     ModRef,
     CardTableModRef,
     CardTableExtension,
     G1SATBCT,
     G1SATBCTLogging,
     Other,
     Uninit
   };
   enum Flags {
     None                = 0,
     TargetUninitialized = 1
   };
 protected:
   int _max_covered_regions;
   Name _kind;
 public:
   BarrierSet() { _kind = Uninit; }
   // To get around prohibition on RTTI.
   BarrierSet::Name kind() { return _kind; }
   virtual bool is_a(BarrierSet::Name bsn) = 0;
   // These operations indicate what kind of barriers the BarrierSet has.
   virtual bool has_read_ref_barrier() = 0;
   virtual bool has_read_prim_barrier() = 0;
   virtual bool has_write_ref_barrier() = 0;
   virtual bool has_write_ref_pre_barrier() = 0;
   virtual bool has_write_prim_barrier() = 0;
   // These functions indicate whether a particular access of the given
   // kinds requires a barrier.
   virtual bool read_ref_needs_barrier(void* field) = 0;
   virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
   virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
                                         juint val1, juint val2) = 0;
   // The first four operations provide a direct implementation of the
   // barrier set.  An interpreter loop, for example, could call these
   // directly, as appropriate.
   // Invoke the barrier, if any, necessary when reading the given ref field.
   virtual void read_ref_field(void* field) = 0;
   // Invoke the barrier, if any, necessary when reading the given primitive
   // "field" of "bytes" bytes in "obj".
   virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
   // Invoke the barrier, if any, necessary when writing "new_val" into the
   // ref field at "offset" in "obj".
   // (For efficiency reasons, this operation is specialized for certain
   // barrier types.  Semantically, it should be thought of as a call to the
   // virtual "_work" function below, which must implement the barrier.)
   // First the pre-write versions...
   template <class T> inline void write_ref_field_pre(T* field, oop new_val);
 private:
   // Keep this private so as to catch violations at build time.
   virtual void write_ref_field_pre_work(     void* field, oop new_val) { guarantee(false, "Not needed"); };
 protected:
   virtual void write_ref_field_pre_work(      oop* field, oop new_val) {};
   virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};
 public:
   // ...then the post-write version.
   inline void write_ref_field(void* field, oop new_val);
 protected:
   virtual void write_ref_field_work(void* field, oop new_val) = 0;
 public:
   // Invoke the barrier, if any, necessary when writing the "bytes"-byte
   // value(s) "val1" (and "val2") into the primitive "field".
   virtual void write_prim_field(HeapWord* field, size_t bytes,
                                 juint val1, juint val2) = 0;
   // Operations on arrays, or general regions (e.g., for "clone") may be
   // optimized by some barriers.
   // The first six operations tell whether such an optimization exists for
   // the particular barrier.
   virtual bool has_read_ref_array_opt() = 0;
   virtual bool has_read_prim_array_opt() = 0;
   virtual bool has_write_ref_array_pre_opt() { return true; }
   virtual bool has_write_ref_array_opt() = 0;
   virtual bool has_write_prim_array_opt() = 0;
   virtual bool has_read_region_opt() = 0;
   virtual bool has_write_region_opt() = 0;
   // These operations should assert false unless the correponding operation
   // above returns true.  Otherwise, they should perform an appropriate
   // barrier for an array whose elements are all in the given memory region.
   virtual void read_ref_array(MemRegion mr) = 0;
   virtual void read_prim_array(MemRegion mr) = 0;
   // Below length is the # array elements being written
   virtual void write_ref_array_pre(oop* dst, int length,
                                    bool dest_uninitialized = false) {}
   virtual void write_ref_array_pre(narrowOop* dst, int length,
                                    bool dest_uninitialized = false) {}
   // Below count is the # array elements being written, starting
   // at the address "start", which may not necessarily be HeapWord-aligned
   inline void write_ref_array(HeapWord* start, size_t count);
   // Static versions, suitable for calling from generated code;
   // count is # array elements being written, starting with "start",
   // which may not necessarily be HeapWord-aligned.
   static void static_write_ref_array_pre(HeapWord* start, size_t count);
   static void static_write_ref_array_post(HeapWord* start, size_t count);
 protected:
   virtual void write_ref_array_work(MemRegion mr) = 0;
 public:
   virtual void write_prim_array(MemRegion mr) = 0;
   virtual void read_region(MemRegion mr) = 0;
   // (For efficiency reasons, this operation is specialized for certain
   // barrier types.  Semantically, it should be thought of as a call to the
   // virtual "_work" function below, which must implement the barrier.)
   inline void write_region(MemRegion mr);
 protected:
   virtual void write_region_work(MemRegion mr) = 0;
 public:
   // Some barrier sets create tables whose elements correspond to parts of
   // the heap; the CardTableModRefBS is an example.  Such barrier sets will
   // normally reserve space for such tables, and commit parts of the table
   // "covering" parts of the heap that are committed.  The constructor is
   // passed the maximum number of independently committable subregions to
   // be covered, and the "resize_covoered_region" function allows the
   // sub-parts of the heap to inform the barrier set of changes of their
   // sizes.
   BarrierSet(int max_covered_regions) :
     _max_covered_regions(max_covered_regions) {}
   // Inform the BarrierSet that the the covered heap region that starts
   // with "base" has been changed to have the given size (possibly from 0,
   // for initialization.)
   virtual void resize_covered_region(MemRegion new_region) = 0;
   // If the barrier set imposes any alignment restrictions on boundaries
   // within the heap, this function tells whether they are met.
   virtual bool is_aligned(HeapWord* addr) = 0;
   // Print a description of the memory for the barrier set
   virtual void print_on(outputStream* st) const = 0;
 };
 #endif // SHARE_VM_MEMORY_BARRIERSET_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/barrierSet.hpp@2c022e432e10 (annotated)

src/share/vm/memory/barrierSet.hpp