1 /*

     2  * Copyright 1997-2004 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 // Interface for updating the instruction cache.  Whenever the VM modifies

    26 // code, part of the processor instruction cache potentially has to be flushed.

    27 

    28 // On the x86, this is a no-op -- the I-cache is guaranteed to be consistent

    29 // after the next jump, and the VM never modifies instructions directly ahead

    30 // of the instruction fetch path.

    31 

    32 // [phh] It's not clear that the above comment is correct, because on an MP

    33 // system where the dcaches are not snooped, only the thread doing the invalidate

    34 // will see the update.  Even in the snooped case, a memory fence would be

    35 // necessary if stores weren't ordered.  Fortunately, they are on all known

    36 // x86 implementations.

    37 

    38 class ICache : public AbstractICache {

    39  public:

    40 #ifdef AMD64

    41   enum {

    42     stub_size      = 64, // Size of the icache flush stub in bytes

    43     line_size      = 32, // Icache line size in bytes

    44     log2_line_size = 5   // log2(line_size)

    45   };

    46 

    47   // Use default implementation

    48 #else

    49   enum {

    50     stub_size      = 16,                 // Size of the icache flush stub in bytes

    51     line_size      = BytesPerWord,      // conservative

    52     log2_line_size = LogBytesPerWord    // log2(line_size)

    53   };

    54 #endif // AMD64

    55 };