Adding gem5 source to svn.

git-svn-id: https://www4.informatik.uni-erlangen.de/i4svn/danceos/trunk/devel/fail@1819 8c4709b5-6ec9-48aa-a5cd-a96041d1645a

simulators/gem5/src/cpu/decode_cache.hh

@@ -0,0 +1,129 @@
+/*
+ * Copyright (c) 2011 Google
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#ifndef __CPU_DECODE_CACHE_HH__
+#define __CPU_DECODE_CACHE_HH__
+
+#include "arch/isa_traits.hh"
+#include "arch/types.hh"
+#include "base/hashmap.hh"
+#include "config/the_isa.hh"
+#include "cpu/static_inst_fwd.hh"
+
+namespace TheISA
+{
+    class Decoder;
+}
+
+namespace DecodeCache
+{
+
+/// Hash for decoded instructions.
+typedef m5::hash_map<TheISA::ExtMachInst, StaticInstPtr> InstMap;
+
+/// A sparse map from an Addr to a Value, stored in page chunks.
+template<class Value>
+class AddrMap
+{
+  protected:
+    // A pages worth of cache entries.
+    struct CachePage {
+        Value items[TheISA::PageBytes];
+    };
+    // A map of cache pages which allows a sparse mapping.
+    typedef typename m5::hash_map<Addr, CachePage *> PageMap;
+    typedef typename PageMap::iterator PageIt;
+    // Mini cache of recent lookups.
+    PageIt recent[2];
+    PageMap pageMap;
+
+    /// Update the mini cache of recent lookups.
+    /// @param recentest The most recent result;
+    void
+    update(PageIt recentest)
+    {
+        recent[1] = recent[0];
+        recent[0] = recentest;
+    }
+
+    /// Attempt to find the CacheePage which goes with a particular
+    /// address. First check the small cache of recent results, then
+    /// actually look in the hash_map.
+    /// @param addr The address to look up.
+    CachePage *
+    getPage(Addr addr)
+    {
+        Addr page_addr = addr & ~(TheISA::PageBytes - 1);
+
+        // Check against recent lookups.
+        if (recent[0] != pageMap.end()) {
+            if (recent[0]->first == page_addr)
+                return recent[0]->second;
+            if (recent[1] != pageMap.end() &&
+                    recent[1]->first == page_addr) {
+                update(recent[1]);
+                // recent[1] has just become recent[0].
+                return recent[0]->second;
+            }
+        }
+
+        // Actually look in the has_map.
+        PageIt it = pageMap.find(page_addr);
+        if (it != pageMap.end()) {
+            update(it);
+            return it->second;
+        }
+
+        // Didn't find an existing page, so add a new one.
+        CachePage *newPage = new CachePage;
+        page_addr = page_addr & ~(TheISA::PageBytes - 1);
+        typename PageMap::value_type to_insert(page_addr, newPage);
+        update(pageMap.insert(to_insert).first);
+        return newPage;
+    }
+
+  public:
+    /// Constructor
+    AddrMap()
+    {
+        recent[0] = recent[1] = pageMap.end();
+    }
+
+    Value &
+    lookup(Addr addr)
+    {
+        CachePage *page = getPage(addr);
+        return page->items[addr & (TheISA::PageBytes - 1)];
+    }
+};
+
+} // namespace DecodeCache
+
+#endif // __CPU_DECODE_CACHE_HH__