fu_pool.hh revision 8229:78bf55f23338 
1/*
2 * Copyright (c) 2006 The Regents of The University of Michigan
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: Kevin Lim
29 */
30
31#ifndef __CPU_O3_FU_POOL_HH__
32#define __CPU_O3_FU_POOL_HH__
33
34#include <bitset>
35#include <list>
36#include <string>
37#include <vector>
38
39#include "cpu/op_class.hh"
40#include "cpu/sched_list.hh"
41#include "params/FUPool.hh"
42#include "sim/sim_object.hh"
43
44class FUDesc;
45class FuncUnit;
46
47/**
48 * Pool of FU's, specific to the new CPU model. The old FU pool had lists of
49 * free units and busy units, and whenever a FU was needed it would iterate
50 * through the free units to find a FU that provided the capability. This pool
51 * has lists of units specific to each of the capabilities, and whenever a FU
52 * is needed, it iterates through that list to find a free unit. The previous
53 * FU pool would have to be ticked each cycle to update which units became
54 * free. This FU pool lets the IEW stage handle freeing units, which frees
55 * them as their scheduled execution events complete. This limits units in this
56 * model to either have identical issue and op latencies, or 1 cycle issue
57 * latencies.
58 */
59class FUPool : public SimObject
60{
61  private:
62    /** Maximum op execution latencies, per op class. */
63    unsigned maxOpLatencies[Num_OpClasses];
64    /** Maximum issue latencies, per op class. */
65    unsigned maxIssueLatencies[Num_OpClasses];
66
67    /** Bitvector listing capabilities of this FU pool. */
68    std::bitset<Num_OpClasses> capabilityList;
69
70    /** Bitvector listing which FUs are busy. */
71    std::vector<bool> unitBusy;
72
73    /** List of units to be freed at the end of this cycle. */
74    std::vector<int> unitsToBeFreed;
75
76    /**
77     * Class that implements a circular queue to hold FU indices. The hope is
78     * that FUs that have been just used will be moved to the end of the queue
79     * by iterating through it, thus leaving free units at the head of the
80     * queue.
81     */
82    class FUIdxQueue {
83      public:
84        /** Constructs a circular queue of FU indices. */
85        FUIdxQueue()
86            : idx(0), size(0)
87        { }
88
89        /** Adds a FU to the queue. */
90        inline void addFU(int fu_idx);
91
92        /** Returns the index of the FU at the head of the queue, and changes
93         *  the index to the next element.
94         */
95        inline int getFU();
96
97      private:
98        /** Circular queue index. */
99        int idx;
100
101        /** Size of the queue. */
102        int size;
103
104        /** Queue of FU indices. */
105        std::vector<int> funcUnitsIdx;
106    };
107
108    /** Per op class queues of FUs that provide that capability. */
109    FUIdxQueue fuPerCapList[Num_OpClasses];
110
111    /** Number of FUs. */
112    int numFU;
113
114    /** Functional units. */
115    std::vector<FuncUnit *> funcUnits;
116
117    typedef std::vector<FuncUnit *>::iterator fuListIterator;
118
119  public:
120    typedef FUPoolParams Params;
121    /** Constructs a FU pool. */
122    FUPool(const Params *p);
123    ~FUPool();
124
125    /** Annotates units that provide memory operations. Included only because
126     *  old FU pool provided this function.
127     */
128    void annotateMemoryUnits(unsigned hit_latency);
129
130    /**
131     * Gets a FU providing the requested capability. Will mark the unit as busy,
132     * but leaves the freeing of the unit up to the IEW stage.
133     * @param capability The capability requested.
134     * @return Returns -2 if the FU pool does not have the capability, -1 if
135     * there is no free FU, and the FU's index otherwise.
136     */
137    int getUnit(OpClass capability);
138
139    /** Frees a FU at the end of this cycle. */
140    void freeUnitNextCycle(int fu_idx);
141
142    /** Frees all FUs on the list. */
143    void processFreeUnits();
144
145    /** Returns the total number of FUs. */
146    int size() { return numFU; }
147
148    /** Debugging function used to dump FU information. */
149    void dump();
150
151    /** Returns the operation execution latency of the given capability. */
152    unsigned getOpLatency(OpClass capability) {
153        return maxOpLatencies[capability];
154    }
155
156    /** Returns the issue latency of the given capability. */
157    unsigned getIssueLatency(OpClass capability) {
158        return maxIssueLatencies[capability];
159    }
160
161    /** Switches out functional unit pool. */
162    void switchOut();
163
164    /** Takes over from another CPU's thread. */
165    void takeOverFrom();
166};
167
168#endif // __CPU_O3_FU_POOL_HH__
169