ISA,CPU: Generalize and split out the components of the decode cache.

This will allow it to be specialized by the ISAs. The existing caching scheme
is provided by the BasicDecodeCache in the GenericISA namespace and is built
from the generalized components.

--HG--
rename : src/cpu/decode_cache.cc => src/arch/generic/decode_cache.cc

3 files changed, 73 insertions, 148 deletions

diff --git a/src/cpu/SConscript b/src/cpu/SConscript
index 4b327f8a1..e1ba59b8b 100644
--- a/src/cpu/SConscript
+++ b/src/cpu/SConscript
@@ -108,7 +108,6 @@ SimObject('NativeTrace.py')
 Source('activity.cc')
 Source('base.cc')
 Source('cpuevent.cc')
-Source('decode_cache.cc')
 Source('exetrace.cc')
 Source('func_unit.cc')
 Source('inteltrace.cc')
diff --git a/src/cpu/decode_cache.cc b/src/cpu/decode_cache.cc
deleted file mode 100644
index 636bf9284..000000000
--- a/src/cpu/decode_cache.cc
+++ /dev/null
@@ -1,113 +0,0 @@
-/*
- * Copyright (c) 2011-2012 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
- */
-
-#include "arch/decoder.hh"
-#include "arch/isa_traits.hh"
-#include "arch/types.hh"
-#include "base/hashmap.hh"
-#include "config/the_isa.hh"
-#include "cpu/static_inst.hh"
-
-void
-DecodeCache::DecodePages::update(PageIt recentest)
-{
-    recent[1] = recent[0];
-    recent[0] = recentest;
-}
-
-void
-DecodeCache::DecodePages::addPage(Addr addr, DecodePage *page)
-{
-    Addr page_addr = addr & ~(TheISA::PageBytes - 1);
-    typename PageMap::value_type to_insert(page_addr, page);
-    update(pageMap.insert(to_insert).first);
-}
-
-DecodeCache::DecodePages::DecodePages()
-{
-    recent[0] = recent[1] = pageMap.end();
-}
-
-DecodeCache::DecodePage *
-DecodeCache::DecodePages::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.
-    DecodePage *newPage = new DecodePage;
-    addPage(page_addr, newPage);
-    return newPage;
-}
-
-StaticInstPtr
-DecodeCache::decode(TheISA::Decoder *decoder,
-        ExtMachInst mach_inst, Addr addr)
-{
-    // Try to find a matching address based table of instructions.
-    DecodePage *page = decodePages.getPage(addr);
-
-    // Use the table to decode the instruction. It will fall back to other
-    // mechanisms if it needs to.
-    Addr offset = addr & (TheISA::PageBytes - 1);
-    StaticInstPtr si = page->insts[offset];
-    if (si && (si->machInst == mach_inst))
-        return si;
-
-    InstMap::iterator iter = instMap.find(mach_inst);
-    if (iter != instMap.end()) {
-        si = iter->second;
-        page->insts[offset] = si;
-        return si;
-    }
-
-    si = decoder->decodeInst(mach_inst);
-    instMap[mach_inst] = si;
-    page->insts[offset] = si;
-    return si;
-}
diff --git a/src/cpu/decode_cache.hh b/src/cpu/decode_cache.hh
index 473340586..34387419f 100644
--- a/src/cpu/decode_cache.hh
+++ b/src/cpu/decode_cache.hh
@@ -35,56 +35,95 @@
 #include "arch/types.hh"
 #include "base/hashmap.hh"
 #include "config/the_isa.hh"
-#include "cpu/static_inst.hh"
+#include "cpu/static_inst_fwd.hh"
 
 namespace TheISA
 {
     class Decoder;
 }
 
-class DecodeCache
+namespace DecodeCache
 {
-  private:
-    typedef TheISA::ExtMachInst ExtMachInst;
 
-    /// Hash of decoded instructions.
-    typedef m5::hash_map<ExtMachInst, StaticInstPtr> InstMap;
-    InstMap instMap;
-    struct DecodePage {
-        StaticInstPtr insts[TheISA::PageBytes];
+/// 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;
+    }
 
-    /// A store of DecodePages. Basically a slightly smarter hash_map.
-    class DecodePages
+    /// 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)
     {
-      protected:
-        typedef typename m5::hash_map<Addr, DecodePage *> PageMap;
-        typedef typename PageMap::iterator PageIt;
-        PageIt recent[2];
-        PageMap pageMap;
+        Addr page_addr = addr & ~(TheISA::PageBytes - 1);
 
-        /// Update the small cache of recent lookups.
-        /// @param recentest The most recent result;
-        void update(PageIt recentest);
-        void addPage(Addr addr, DecodePage *page);
+        // 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;
+            }
+        }
 
-      public:
-        /// Constructor
-        DecodePages();
+        // Actually look in the has_map.
+        PageIt it = pageMap.find(page_addr);
+        if (it != pageMap.end()) {
+            update(it);
+            return it->second;
+        }
 
-        /// Attempt to find the DecodePage 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.
-        DecodePage *getPage(Addr addr);
-    } decodePages;
+        // 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:
-    /// Decode a machine instruction.
-    /// @param mach_inst The binary instruction to decode.
-    /// @retval A pointer to the corresponding StaticInst object.
-    StaticInstPtr decode(TheISA::Decoder * const decoder,
-            ExtMachInst mach_inst, Addr addr);
+    /// 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__