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; --- 21 unchanged lines hidden (view full) --- 30 31#ifndef __CPU_DECODE_CACHE_HH__ 32#define __CPU_DECODE_CACHE_HH__ 33 34#include "arch/isa_traits.hh" 35#include "arch/types.hh" 36#include "base/hashmap.hh" 37#include "config/the_isa.hh" |
38#include "cpu/static_inst_fwd.hh" |
39 40namespace TheISA 41{ 42 class Decoder; 43} 44 |
45namespace DecodeCache |
46{ |
47 |
48/// Hash for decoded instructions. 49typedef m5::hash_map<TheISA::ExtMachInst, StaticInstPtr> InstMap; 50 51/// A sparse map from an Addr to a Value, stored in page chunks. 52template<class Value> 53class AddrMap 54{ 55 protected: 56 // A pages worth of cache entries. 57 struct CachePage { 58 Value items[TheISA::PageBytes]; |
59 }; |
60 // A map of cache pages which allows a sparse mapping. 61 typedef typename m5::hash_map<Addr, CachePage *> PageMap; 62 typedef typename PageMap::iterator PageIt; 63 // Mini cache of recent lookups. 64 PageIt recent[2]; 65 PageMap pageMap; |
66 |
67 /// Update the mini cache of recent lookups. 68 /// @param recentest The most recent result; 69 void 70 update(PageIt recentest) |
71 { |
72 recent[1] = recent[0]; 73 recent[0] = recentest; 74 } |
75 |
76 /// Attempt to find the CacheePage which goes with a particular 77 /// address. First check the small cache of recent results, then 78 /// actually look in the hash_map. 79 /// @param addr The address to look up. 80 CachePage * 81 getPage(Addr addr) 82 { 83 Addr page_addr = addr & ~(TheISA::PageBytes - 1); |
84 |
85 // Check against recent lookups. 86 if (recent[0] != pageMap.end()) { 87 if (recent[0]->first == page_addr) 88 return recent[0]->second; 89 if (recent[1] != pageMap.end() && 90 recent[1]->first == page_addr) { 91 update(recent[1]); 92 // recent[1] has just become recent[0]. 93 return recent[0]->second; 94 } 95 } |
96 |
97 // Actually look in the has_map. 98 PageIt it = pageMap.find(page_addr); 99 if (it != pageMap.end()) { 100 update(it); 101 return it->second; 102 } |
103 |
104 // Didn't find an existing page, so add a new one. 105 CachePage *newPage = new CachePage; 106 page_addr = page_addr & ~(TheISA::PageBytes - 1); 107 typename PageMap::value_type to_insert(page_addr, newPage); 108 update(pageMap.insert(to_insert).first); 109 return newPage; 110 } 111 |
112 public: |
113 /// Constructor 114 AddrMap() 115 { 116 recent[0] = recent[1] = pageMap.end(); 117 } 118 119 Value & 120 lookup(Addr addr) 121 { 122 CachePage *page = getPage(addr); 123 return page->items[addr & (TheISA::PageBytes - 1)]; 124 } |
125}; 126 |
127} // namespace DecodeCache 128 |
129#endif // __CPU_DECODE_CACHE_HH__ |