barrierSet.hpp revision 113
2362N/A * Copyright 2000-2002 Sun Microsystems, Inc. All Rights Reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 0N/A * published by the Free Software Foundation. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 2362N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 0N/A * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 0N/A * CA 95054 USA or visit www.sun.com if you need additional information or 0N/A * have any questions. 0N/A// This class provides the interface between a barrier implementation and 0N/A// the rest of the system. 0N/A // To get around prohibition on RTTI. 0N/A // These operations indicate what kind of barriers the BarrierSet has. 0N/A // These functions indicate whether a particular access of the given 0N/A // kinds requires a barrier. 0N/A // The first four operations provide a direct implementation of the 0N/A // barrier set. An interpreter loop, for example, could call these 0N/A // directly, as appropriate. 0N/A // Invoke the barrier, if any, necessary when reading the given ref field. 0N/A // Invoke the barrier, if any, necessary when reading the given primitive 0N/A // "field" of "bytes" bytes in "obj". 0N/A // Invoke the barrier, if any, necessary when writing "new_val" into the 0N/A // ref field at "offset" in "obj". 0N/A // (For efficiency reasons, this operation is specialized for certain 0N/A // barrier types. Semantically, it should be thought of as a call to the 0N/A // virtual "_work" function below, which must implement the barrier.) 0N/A // Invoke the barrier, if any, necessary when writing the "bytes"-byte 0N/A // value(s) "val1" (and "val2") into the primitive "field". // 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. // 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. // (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.) // 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 // Generates code to invoke the barrier, if any, necessary when reading // the ref field at "offset" in "obj". // Generates code to invoke the barrier, if any, necessary when reading // the primitive field of "bytes" bytes at offset" in "obj". // Generates code to invoke the barrier, if any, necessary when writing // "new_val" into the ref field at "offset" in "obj". // Generates code to invoke the barrier, if any, necessary when writing // the "bytes"-byte value "new_val" into the primitive field at "offset" // 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 // Inform the BarrierSet that the the covered heap region that starts // with "base" has been changed to have the given size (possibly from 0, // If the barrier set imposes any alignment restrictions on boundaries // within the heap, this function tells whether they are met.