1 /*
   2  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  23  */
  24 
  25 #ifndef SHARE_VM_RUNTIME_PREFETCH_HPP
  26 #define SHARE_VM_RUNTIME_PREFETCH_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 
  30 // If calls to prefetch methods are in a loop, the loop should be cloned
  31 // such that if Prefetch{Scan,Copy}Interval and/or PrefetchFieldInterval
  32 // say not to do prefetching, these methods aren't called.  At the very
  33 // least, they take up a memory issue slot.  They should be implemented
  34 // as inline assembly code: doing an actual call isn't worth the cost.
  35 
  36 class Prefetch : AllStatic {
  37  public:
  38   enum style {
  39     do_none,  // Do no prefetching
  40     do_read,  // Do read prefetching
  41     do_write  // Do write prefetching
  42   };
  43 
  44   // Prefetch anticipating read; must not fault, semantically a no-op
  45   static void read(void* loc, intx interval);
  46 
  47   // Prefetch anticipating write; must not fault, semantically a no-op
  48   static void write(void* loc, intx interval);
  49 };
  50 
  51 #endif // SHARE_VM_RUNTIME_PREFETCH_HPP