fu_pool.hh revision 8737:770ccf3af571 
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 "params/FUPool.hh"
41#include "sim/sim_object.hh"
42
43class FUDesc;
44class FuncUnit;
45
46/**
47 * Pool of FU's, specific to the new CPU model. The old FU pool had lists of
48 * free units and busy units, and whenever a FU was needed it would iterate
49 * through the free units to find a FU that provided the capability. This pool
50 * has lists of units specific to each of the capabilities, and whenever a FU
51 * is needed, it iterates through that list to find a free unit. The previous
52 * FU pool would have to be ticked each cycle to update which units became
53 * free. This FU pool lets the IEW stage handle freeing units, which frees
54 * them as their scheduled execution events complete. This limits units in this
55 * model to either have identical issue and op latencies, or 1 cycle issue
56 * latencies.
57 */
58class FUPool : public SimObject
59{
60  private:
61    /** Maximum op execution latencies, per op class. */
62    unsigned maxOpLatencies[Num_OpClasses];
63    /** Maximum issue latencies, per op class. */
64    unsigned maxIssueLatencies[Num_OpClasses];
65
66    /** Bitvector listing capabilities of this FU pool. */
67    std::bitset<Num_OpClasses> capabilityList;
68
69    /** Bitvector listing which FUs are busy. */
70    std::vector<bool> unitBusy;
71
72    /** List of units to be freed at the end of this cycle. */
73    std::vector<int> unitsToBeFreed;
74
75    /**
76     * Class that implements a circular queue to hold FU indices. The hope is
77     * that FUs that have been just used will be moved to the end of the queue
78     * by iterating through it, thus leaving free units at the head of the
79     * queue.
80     */
81    class FUIdxQueue {
82      public:
83        /** Constructs a circular queue of FU indices. */
84        FUIdxQueue()
85            : idx(0), size(0)
86        { }
87
88        /** Adds a FU to the queue. */
89        inline void addFU(int fu_idx);
90
91        /** Returns the index of the FU at the head of the queue, and changes
92         *  the index to the next element.
93         */
94        inline int getFU();
95
96      private:
97        /** Circular queue index. */
98        int idx;
99
100        /** Size of the queue. */
101        int size;
102
103        /** Queue of FU indices. */
104        std::vector<int> funcUnitsIdx;
105    };
106
107    /** Per op class queues of FUs that provide that capability. */
108    FUIdxQueue fuPerCapList[Num_OpClasses];
109
110    /** Number of FUs. */
111    int numFU;
112
113    /** Functional units. */
114    std::vector<FuncUnit *> funcUnits;
115
116    typedef std::vector<FuncUnit *>::iterator fuListIterator;
117
118  public:
119    typedef FUPoolParams Params;
120    /** Constructs a FU pool. */
121    FUPool(const Params *p);
122    ~FUPool();
123
124    /** Annotates units that provide memory operations. Included only because
125     *  old FU pool provided this function.
126     */
127    void annotateMemoryUnits(unsigned hit_latency);
128
129    /**
130     * Gets a FU providing the requested capability. Will mark the unit as busy,
131     * but leaves the freeing of the unit up to the IEW stage.
132     * @param capability The capability requested.
133     * @return Returns -2 if the FU pool does not have the capability, -1 if
134     * there is no free FU, and the FU's index otherwise.
135     */
136    int getUnit(OpClass capability);
137
138    /** Frees a FU at the end of this cycle. */
139    void freeUnitNextCycle(int fu_idx);
140
141    /** Frees all FUs on the list. */
142    void processFreeUnits();
143
144    /** Returns the total number of FUs. */
145    int size() { return numFU; }
146
147    /** Debugging function used to dump FU information. */
148    void dump();
149
150    /** Returns the operation execution latency of the given capability. */
151    unsigned getOpLatency(OpClass capability) {
152        return maxOpLatencies[capability];
153    }
154
155    /** Returns the issue latency of the given capability. */
156    unsigned getIssueLatency(OpClass capability) {
157        return maxIssueLatencies[capability];
158    }
159
160    /** Switches out functional unit pool. */
161    void switchOut();
162
163    /** Takes over from another CPU's thread. */
164    void takeOver();
165};
166
167#endif // __CPU_O3_FU_POOL_HH__
168