/*

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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).

 *

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 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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#ifndef CPU_X86_VM_ICACHE_X86_HPP

#define CPU_X86_VM_ICACHE_X86_HPP

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

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

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

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

// of the instruction fetch path.

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

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

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

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

// x86 implementations.

class ICache : public AbstractICache {

 public:

#ifdef AMD64

  enum {

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

    line_size      = 32, // Icache line size in bytes

    log2_line_size = 5   // log2(line_size)

  };

  // Use default implementation

#else

  enum {

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

    line_size      = BytesPerWord,      // conservative

    log2_line_size = LogBytesPerWord    // log2(line_size)

  };

#endif // AMD64

};

#endif // CPU_X86_VM_ICACHE_X86_HPP