duke@435: /*
xdono@631:  * Copyright 2000-2008 Sun Microsystems, Inc.  All Rights Reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: // This class provides the interface between a barrier implementation and
duke@435: // the rest of the system.
duke@435: 
duke@435: class BarrierSet: public CHeapObj {
duke@435:   friend class VMStructs;
duke@435: public:
duke@435:   enum Name {
duke@435:     ModRef,
duke@435:     CardTableModRef,
duke@435:     CardTableExtension,
ysr@777:     G1SATBCT,
ysr@777:     G1SATBCTLogging,
duke@435:     Other,
duke@435:     Uninit
duke@435:   };
duke@435: 
duke@435: protected:
duke@435:   int _max_covered_regions;
duke@435:   Name _kind;
duke@435: 
duke@435: public:
duke@435: 
ysr@777:   BarrierSet() { _kind = Uninit; }
duke@435:   // To get around prohibition on RTTI.
ysr@777:   BarrierSet::Name kind() { return _kind; }
duke@435:   virtual bool is_a(BarrierSet::Name bsn) = 0;
duke@435: 
duke@435:   // These operations indicate what kind of barriers the BarrierSet has.
duke@435:   virtual bool has_read_ref_barrier() = 0;
duke@435:   virtual bool has_read_prim_barrier() = 0;
duke@435:   virtual bool has_write_ref_barrier() = 0;
ysr@777:   virtual bool has_write_ref_pre_barrier() = 0;
duke@435:   virtual bool has_write_prim_barrier() = 0;
duke@435: 
duke@435:   // These functions indicate whether a particular access of the given
duke@435:   // kinds requires a barrier.
coleenp@548:   virtual bool read_ref_needs_barrier(void* field) = 0;
duke@435:   virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0;
coleenp@548:   virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;
ysr@777:   virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
ysr@777:                                         juint val1, juint val2) = 0;
duke@435: 
duke@435:   // The first four operations provide a direct implementation of the
duke@435:   // barrier set.  An interpreter loop, for example, could call these
duke@435:   // directly, as appropriate.
duke@435: 
duke@435:   // Invoke the barrier, if any, necessary when reading the given ref field.
coleenp@548:   virtual void read_ref_field(void* field) = 0;
duke@435: 
duke@435:   // Invoke the barrier, if any, necessary when reading the given primitive
duke@435:   // "field" of "bytes" bytes in "obj".
duke@435:   virtual void read_prim_field(HeapWord* field, size_t bytes) = 0;
duke@435: 
duke@435:   // Invoke the barrier, if any, necessary when writing "new_val" into the
duke@435:   // ref field at "offset" in "obj".
duke@435:   // (For efficiency reasons, this operation is specialized for certain
duke@435:   // barrier types.  Semantically, it should be thought of as a call to the
duke@435:   // virtual "_work" function below, which must implement the barrier.)
ysr@777:   // First the pre-write versions...
ysr@1280:   template <class T> inline void write_ref_field_pre(T* field, oop new_val);
ysr@1280: private:
ysr@1280:   // Keep this private so as to catch violations at build time.
ysr@1280:   virtual void write_ref_field_pre_work(     void* field, oop new_val) { guarantee(false, "Not needed"); };
ysr@777: protected:
ysr@1280:   virtual void write_ref_field_pre_work(      oop* field, oop new_val) {};
ysr@1280:   virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {};
ysr@777: public:
ysr@777: 
ysr@777:   // ...then the post-write version.
coleenp@548:   inline void write_ref_field(void* field, oop new_val);
duke@435: protected:
coleenp@548:   virtual void write_ref_field_work(void* field, oop new_val) = 0;
duke@435: public:
duke@435: 
duke@435:   // Invoke the barrier, if any, necessary when writing the "bytes"-byte
duke@435:   // value(s) "val1" (and "val2") into the primitive "field".
duke@435:   virtual void write_prim_field(HeapWord* field, size_t bytes,
duke@435:                                 juint val1, juint val2) = 0;
duke@435: 
duke@435:   // Operations on arrays, or general regions (e.g., for "clone") may be
duke@435:   // optimized by some barriers.
duke@435: 
duke@435:   // The first six operations tell whether such an optimization exists for
duke@435:   // the particular barrier.
duke@435:   virtual bool has_read_ref_array_opt() = 0;
duke@435:   virtual bool has_read_prim_array_opt() = 0;
ysr@777:   virtual bool has_write_ref_array_pre_opt() { return true; }
duke@435:   virtual bool has_write_ref_array_opt() = 0;
duke@435:   virtual bool has_write_prim_array_opt() = 0;
duke@435: 
duke@435:   virtual bool has_read_region_opt() = 0;
duke@435:   virtual bool has_write_region_opt() = 0;
duke@435: 
duke@435:   // These operations should assert false unless the correponding operation
duke@435:   // above returns true.  Otherwise, they should perform an appropriate
duke@435:   // barrier for an array whose elements are all in the given memory region.
duke@435:   virtual void read_ref_array(MemRegion mr) = 0;
duke@435:   virtual void read_prim_array(MemRegion mr) = 0;
duke@435: 
ysr@1280:   virtual void write_ref_array_pre(      oop* dst, int length) {}
ysr@1280:   virtual void write_ref_array_pre(narrowOop* dst, int length) {}
duke@435:   inline void write_ref_array(MemRegion mr);
ysr@777: 
ysr@777:   // Static versions, suitable for calling from generated code.
ysr@777:   static void static_write_ref_array_pre(HeapWord* start, size_t count);
ysr@777:   static void static_write_ref_array_post(HeapWord* start, size_t count);
ysr@1280:   // Narrow oop versions of the above; count is # of array elements being written,
ysr@1280:   // starting with "start", which is HeapWord-aligned.
ysr@1280:   static void static_write_ref_array_pre_narrow(HeapWord* start, size_t count);
ysr@1280:   static void static_write_ref_array_post_narrow(HeapWord* start, size_t count);
ysr@777: 
duke@435: protected:
duke@435:   virtual void write_ref_array_work(MemRegion mr) = 0;
duke@435: public:
duke@435:   virtual void write_prim_array(MemRegion mr) = 0;
duke@435: 
duke@435:   virtual void read_region(MemRegion mr) = 0;
duke@435: 
duke@435:   // (For efficiency reasons, this operation is specialized for certain
duke@435:   // barrier types.  Semantically, it should be thought of as a call to the
duke@435:   // virtual "_work" function below, which must implement the barrier.)
duke@435:   inline void write_region(MemRegion mr);
duke@435: protected:
duke@435:   virtual void write_region_work(MemRegion mr) = 0;
duke@435: public:
duke@435: 
duke@435:   // Some barrier sets create tables whose elements correspond to parts of
duke@435:   // the heap; the CardTableModRefBS is an example.  Such barrier sets will
duke@435:   // normally reserve space for such tables, and commit parts of the table
duke@435:   // "covering" parts of the heap that are committed.  The constructor is
duke@435:   // passed the maximum number of independently committable subregions to
duke@435:   // be covered, and the "resize_covoered_region" function allows the
duke@435:   // sub-parts of the heap to inform the barrier set of changes of their
duke@435:   // sizes.
duke@435:   BarrierSet(int max_covered_regions) :
duke@435:     _max_covered_regions(max_covered_regions) {}
duke@435: 
duke@435:   // Inform the BarrierSet that the the covered heap region that starts
duke@435:   // with "base" has been changed to have the given size (possibly from 0,
duke@435:   // for initialization.)
duke@435:   virtual void resize_covered_region(MemRegion new_region) = 0;
duke@435: 
duke@435:   // If the barrier set imposes any alignment restrictions on boundaries
duke@435:   // within the heap, this function tells whether they are met.
duke@435:   virtual bool is_aligned(HeapWord* addr) = 0;
duke@435: 
duke@435: };