19df4e94ee
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
130 lines
4.1 KiB
C++
130 lines
4.1 KiB
C++
/*
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* Copyright (c) 2011 Google
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Gabe Black
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*/
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#ifndef __CPU_DECODE_CACHE_HH__
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#define __CPU_DECODE_CACHE_HH__
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#include "arch/isa_traits.hh"
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#include "arch/types.hh"
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#include "base/hashmap.hh"
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#include "config/the_isa.hh"
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#include "cpu/static_inst_fwd.hh"
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namespace TheISA
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{
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class Decoder;
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}
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namespace DecodeCache
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{
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/// Hash for decoded instructions.
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typedef m5::hash_map<TheISA::ExtMachInst, StaticInstPtr> InstMap;
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/// A sparse map from an Addr to a Value, stored in page chunks.
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template<class Value>
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class AddrMap
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{
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protected:
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// A pages worth of cache entries.
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struct CachePage {
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Value items[TheISA::PageBytes];
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};
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// A map of cache pages which allows a sparse mapping.
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typedef typename m5::hash_map<Addr, CachePage *> PageMap;
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typedef typename PageMap::iterator PageIt;
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// Mini cache of recent lookups.
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PageIt recent[2];
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PageMap pageMap;
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/// Update the mini cache of recent lookups.
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/// @param recentest The most recent result;
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void
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update(PageIt recentest)
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{
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recent[1] = recent[0];
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recent[0] = recentest;
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}
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/// Attempt to find the CacheePage which goes with a particular
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/// address. First check the small cache of recent results, then
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/// actually look in the hash_map.
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/// @param addr The address to look up.
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CachePage *
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getPage(Addr addr)
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{
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Addr page_addr = addr & ~(TheISA::PageBytes - 1);
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// Check against recent lookups.
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if (recent[0] != pageMap.end()) {
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if (recent[0]->first == page_addr)
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return recent[0]->second;
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if (recent[1] != pageMap.end() &&
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recent[1]->first == page_addr) {
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update(recent[1]);
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// recent[1] has just become recent[0].
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return recent[0]->second;
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}
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}
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// Actually look in the has_map.
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PageIt it = pageMap.find(page_addr);
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if (it != pageMap.end()) {
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update(it);
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return it->second;
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}
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// Didn't find an existing page, so add a new one.
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CachePage *newPage = new CachePage;
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page_addr = page_addr & ~(TheISA::PageBytes - 1);
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typename PageMap::value_type to_insert(page_addr, newPage);
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update(pageMap.insert(to_insert).first);
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return newPage;
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}
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public:
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/// Constructor
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AddrMap()
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{
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recent[0] = recent[1] = pageMap.end();
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}
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Value &
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lookup(Addr addr)
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{
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CachePage *page = getPage(addr);
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return page->items[addr & (TheISA::PageBytes - 1)];
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}
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};
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} // namespace DecodeCache
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#endif // __CPU_DECODE_CACHE_HH__
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