decode_cache.hh revision 9022:bb25e7646c41 
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 "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"
39
40namespace TheISA
41{
42    class Decoder;
43}
44
45class DecodeCache
46{
47  private:
48    typedef TheISA::ExtMachInst ExtMachInst;
49
50    /// Hash of decoded instructions.
51    typedef m5::hash_map<ExtMachInst, StaticInstPtr> InstMap;
52    InstMap instMap;
53    struct DecodePage {
54        StaticInstPtr insts[TheISA::PageBytes];
55    };
56
57    /// A store of DecodePages. Basically a slightly smarter hash_map.
58    class DecodePages
59    {
60      protected:
61        typedef typename m5::hash_map<Addr, DecodePage *> PageMap;
62        typedef typename PageMap::iterator PageIt;
63        PageIt recent[2];
64        PageMap pageMap;
65
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);
70
71      public:
72        /// Constructor
73        DecodePages();
74
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;
81
82  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);
88};
89
90#endif // __CPU_DECODE_CACHE_HH__
91