decode_cache.hh revision 11168
1/* 2 * Copyright (c) 2011 Google 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Gabe Black 29 */ 30 31#ifndef __CPU_DECODE_CACHE_HH__ 32#define __CPU_DECODE_CACHE_HH__ 33 34#include <unordered_map> 35 36#include "arch/isa_traits.hh" 37#include "arch/types.hh" 38#include "config/the_isa.hh" 39#include "cpu/static_inst_fwd.hh" 40 41namespace TheISA 42{ 43 class Decoder; 44} 45 46namespace DecodeCache 47{ 48 49/// Hash for decoded instructions. 50typedef std::unordered_map<TheISA::ExtMachInst, StaticInstPtr> InstMap; 51 52/// A sparse map from an Addr to a Value, stored in page chunks. 53template<class Value> 54class AddrMap 55{ 56 protected: 57 // A pages worth of cache entries. 58 struct CachePage { 59 Value items[TheISA::PageBytes]; 60 }; 61 // A map of cache pages which allows a sparse mapping. 62 typedef typename std::unordered_map<Addr, CachePage *> PageMap; 63 typedef typename PageMap::iterator PageIt; 64 // Mini cache of recent lookups. 65 PageIt recent[2]; 66 PageMap pageMap; 67 68 /// Update the mini cache of recent lookups. 69 /// @param recentest The most recent result; 70 void 71 update(PageIt recentest) 72 { 73 recent[1] = recent[0]; 74 recent[0] = recentest; 75 } 76 77 /// Attempt to find the CacheePage which goes with a particular 78 /// address. First check the small cache of recent results, then 79 /// actually look in the hash map. 80 /// @param addr The address to look up. 81 CachePage * 82 getPage(Addr addr) 83 { 84 Addr page_addr = addr & ~(TheISA::PageBytes - 1); 85 86 // Check against recent lookups. 87 if (recent[0] != pageMap.end()) { 88 if (recent[0]->first == page_addr) 89 return recent[0]->second; 90 if (recent[1] != pageMap.end() && 91 recent[1]->first == page_addr) { 92 update(recent[1]); 93 // recent[1] has just become recent[0]. 94 return recent[0]->second; 95 } 96 } 97 98 // Actually look in the has_map. 99 PageIt it = pageMap.find(page_addr); 100 if (it != pageMap.end()) { 101 update(it); 102 return it->second; 103 } 104 105 // Didn't find an existing page, so add a new one. 106 CachePage *newPage = new CachePage; 107 page_addr = page_addr & ~(TheISA::PageBytes - 1); 108 typename PageMap::value_type to_insert(page_addr, newPage); 109 update(pageMap.insert(to_insert).first); 110 return newPage; 111 } 112 113 public: 114 /// Constructor 115 AddrMap() 116 { 117 recent[0] = recent[1] = pageMap.end(); 118 } 119 120 Value & 121 lookup(Addr addr) 122 { 123 CachePage *page = getPage(addr); 124 return page->items[addr & (TheISA::PageBytes - 1)]; 125 } 126}; 127 128} // namespace DecodeCache 129 130#endif // __CPU_DECODE_CACHE_HH__ 131