| /* |
| * Copyright 2000-2002 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| // This class provides the interface between a barrier implementation and |
| // the rest of the system. |
| |
| class BarrierSet: public CHeapObj { |
| friend class VMStructs; |
| public: |
| enum Name { |
| ModRef, |
| CardTableModRef, |
| CardTableExtension, |
| Other, |
| Uninit |
| }; |
| |
| protected: |
| int _max_covered_regions; |
| Name _kind; |
| |
| public: |
| |
| // To get around prohibition on RTTI. |
| virtual 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_prim_barrier() = 0; |
| |
| // These functions indicate whether a particular access of the given |
| // kinds requires a barrier. |
| virtual bool read_ref_needs_barrier(oop* field) = 0; |
| virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0; |
| virtual bool write_ref_needs_barrier(oop* field, oop new_val) = 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(oop* 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.) |
| inline void write_ref_field(oop* field, oop new_val); |
| protected: |
| virtual void write_ref_field_work(oop* 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_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; |
| |
| inline void write_ref_array(MemRegion mr); |
| 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: |
| |
| // The remaining sets of operations are called by compilers or other code |
| // generators to insert barriers into generated code. There may be |
| // several such code generators; the signatures of these |
| // barrier-generating functions may differ from generator to generator. |
| // There will be a set of four function signatures for each code |
| // generator, which accomplish the generation of barriers of the four |
| // kinds listed above. |
| |
| #ifdef TBD |
| // Generates code to invoke the barrier, if any, necessary when reading |
| // the ref field at "offset" in "obj". |
| virtual void gen_read_ref_field() = 0; |
| |
| // Generates code to invoke the barrier, if any, necessary when reading |
| // the primitive field of "bytes" bytes at offset" in "obj". |
| virtual void gen_read_prim_field() = 0; |
| |
| // Generates code to invoke the barrier, if any, necessary when writing |
| // "new_val" into the ref field at "offset" in "obj". |
| virtual void gen_write_ref_field() = 0; |
| |
| // Generates code to invoke the barrier, if any, necessary when writing |
| // the "bytes"-byte value "new_val" into the primitive field at "offset" |
| // in "obj". |
| virtual void gen_write_prim_field() = 0; |
| #endif |
| |
| // 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; |
| |
| }; |