fu_pool.hh revision 2292 
1/*
2 * Copyright (c) 2002-2005 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
29#ifndef __CPU_O3_FU_POOL_HH__
30#define __CPU_O3_FU_POOL_HH__
31
32#include <bitset>
33#include <list>
34#include <string>
35#include <vector>
36
37#include "base/sched_list.hh"
38#include "encumbered/cpu/full/op_class.hh"
39#include "sim/sim_object.hh"
40
41class FUDesc;
42class FuncUnit;
43
44/**
45 * Pool of FU's, specific to the new CPU model. The old FU pool had lists of
46 * free units and busy units, and whenever a FU was needed it would iterate
47 * through the free units to find a FU that provided the capability. This pool
48 * has lists of units specific to each of the capabilities, and whenever a FU
49 * is needed, it iterates through that list to find a free unit. The previous
50 * FU pool would have to be ticked each cycle to update which units became
51 * free. This FU pool lets the IEW stage handle freeing units, which frees
52 * them as their scheduled execution events complete. This limits units in this
53 * model to either have identical issue and op latencies, or 1 cycle issue
54 * latencies.
55 */
56class FUPool : public SimObject
57{
58  private:
59    /** Maximum op execution latencies, per op class. */
60    unsigned maxOpLatencies[Num_OpClasses];
61    /** Maximum issue latencies, per op class. */
62    unsigned maxIssueLatencies[Num_OpClasses];
63
64    /** Bitvector listing capabilities of this FU pool. */
65    std::bitset<Num_OpClasses> capabilityList;
66
67    /** Bitvector listing which FUs are busy. */
68    std::vector<bool> unitBusy;
69
70    /** List of units to be freed at the end of this cycle. */
71    std::vector<int> unitsToBeFreed;
72
73    /**
74     * Class that implements a circular queue to hold FU indices. The hope is
75     * that FUs that have been just used will be moved to the end of the queue
76     * by iterating through it, thus leaving free units at the head of the
77     * queue.
78     */
79    class FUIdxQueue {
80      public:
81        /** Constructs a circular queue of FU indices. */
82        FUIdxQueue()
83            : idx(0), size(0)
84        { }
85
86        /** Adds a FU to the queue. */
87        inline void addFU(int fu_idx);
88
89        /** Returns the index of the FU at the head of the queue, and changes
90         *  the index to the next element.
91         */
92        inline int getFU();
93
94      private:
95        /** Circular queue index. */
96        int idx;
97
98        /** Size of the queue. */
99        int size;
100
101        /** Queue of FU indices. */
102        std::vector<int> funcUnitsIdx;
103    };
104
105    /** Per op class queues of FUs that provide that capability. */
106    FUIdxQueue fuPerCapList[Num_OpClasses];
107
108    /** Number of FUs. */
109    int numFU;
110
111    /** Functional units. */
112    std::vector<FuncUnit *> funcUnits;
113
114    typedef std::vector<FuncUnit *>::iterator fuListIterator;
115
116  public:
117
118    /** Constructs a FU pool. */
119    FUPool(std::string name, std::vector<FUDesc *> l);
120    ~FUPool();
121
122    /** Annotates units that provide memory operations. Included only because
123     *  old FU pool provided this function.
124     */
125    void annotateMemoryUnits(unsigned hit_latency);
126
127    /**
128     * Gets a FU providing the requested capability. Will mark the unit as busy,
129     * but leaves the freeing of the unit up to the IEW stage.
130     * @param capability The capability requested.
131     * @return Returns -2 if the FU pool does not have the capability, -1 if
132     * there is no free FU, and the FU's index otherwise.
133     */
134    int getUnit(OpClass capability);
135
136    /** Frees a FU at the end of this cycle. */
137    void freeUnit(int fu_idx);
138
139    /** Frees all FUs on the list. */
140    void processFreeUnits();
141
142    /** Returns the total number of FUs. */
143    int size() { return numFU; }
144
145    /** Debugging function used to dump FU information. */
146    void dump();
147
148    /** Returns the operation execution latency of the given capability. */
149    unsigned getOpLatency(OpClass capability) {
150        return maxOpLatencies[capability];
151    }
152
153    /** Returns the issue latency of the given capability. */
154    unsigned getIssueLatency(OpClass capability) {
155        return maxIssueLatencies[capability];
156    }
157};
158
159#endif // __CPU_O3_FU_POOL_HH__
160