decode_cache.hh (9022:bb25e7646c41) decode_cache.hh (9024:5851586f399c)
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;

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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"
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.hh"
38#include "cpu/static_inst_fwd.hh"
39
40namespace TheISA
41{
42 class Decoder;
43}
44
39
40namespace TheISA
41{
42 class Decoder;
43}
44
45class DecodeCache
45namespace DecodeCache
46{
46{
47 private:
48 typedef TheISA::ExtMachInst ExtMachInst;
49
47
50 /// Hash of decoded instructions.
51 typedef m5::hash_map<ExtMachInst, StaticInstPtr> InstMap;
52 InstMap instMap;
53 struct DecodePage {
54 StaticInstPtr insts[TheISA::PageBytes];
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];
55 };
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;
56
66
57 /// A store of DecodePages. Basically a slightly smarter hash_map.
58 class DecodePages
67 /// Update the mini cache of recent lookups.
68 /// @param recentest The most recent result;
69 void
70 update(PageIt recentest)
59 {
71 {
60 protected:
61 typedef typename m5::hash_map<Addr, DecodePage *> PageMap;
62 typedef typename PageMap::iterator PageIt;
63 PageIt recent[2];
64 PageMap pageMap;
72 recent[1] = recent[0];
73 recent[0] = recentest;
74 }
65
75
66 /// Update the small cache of recent lookups.
67 /// @param recentest The most recent result;
68 void update(PageIt recentest);
69 void addPage(Addr addr, DecodePage *page);
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);
70
84
71 public:
72 /// Constructor
73 DecodePages();
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 }
74
96
75 /// Attempt to find the DecodePage which goes with a particular
76 /// address. First check the small cache of recent results, then
77 /// actually look in the hash_map.
78 /// @param addr The address to look up.
79 DecodePage *getPage(Addr addr);
80 } decodePages;
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 }
81
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
82 public:
112 public:
83 /// Decode a machine instruction.
84 /// @param mach_inst The binary instruction to decode.
85 /// @retval A pointer to the corresponding StaticInst object.
86 StaticInstPtr decode(TheISA::Decoder * const decoder,
87 ExtMachInst mach_inst, Addr addr);
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 }
88};
89
125};
126
127} // namespace DecodeCache
128
90#endif // __CPU_DECODE_CACHE_HH__
129#endif // __CPU_DECODE_CACHE_HH__