scoreboard.hh revision 9916 
1/*
2 * Copyright (c) 2005-2006 The Regents of The University of Michigan
3 * Copyright (c) 2013 Advanced Micro Devices, Inc.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Korey Sewell
30 *          Kevin Lim
31 *          Steve Reinhardt
32 */
33
34#ifndef __CPU_O3_SCOREBOARD_HH__
35#define __CPU_O3_SCOREBOARD_HH__
36
37#include <iostream>
38#include <utility>
39#include <vector>
40
41#include "base/trace.hh"
42#include "config/the_isa.hh"
43#include "cpu/o3/comm.hh"
44#include "debug/Scoreboard.hh"
45
46/**
47 * Implements a simple scoreboard to track which registers are
48 * ready. This class operates on the unified physical register space,
49 * so integer and floating-point registers are not distinguished.  For
50 * convenience, it also accepts operations on the physical-space
51 * mapping of misc registers, which are numbered starting after the
52 * end of the actual physical register file.  However, there is no
53 * actual scoreboard for misc registers, and they are always
54 * considered ready.
55 */
56class Scoreboard
57{
58  private:
59    /** The object name, for DPRINTF.  We have to declare this
60     *  explicitly because Scoreboard is not a SimObject. */
61    const std::string _name;
62
63    /** Scoreboard of physical integer registers, saying whether or not they
64     *  are ready. */
65    std::vector<bool> regScoreBoard;
66
67    /** The number of actual physical registers */
68    unsigned numPhysRegs;
69
70    /**
71     * The total number of registers which can be indexed, including
72     * the misc registers that come after the physical registers and
73     * which are hardwired to be always considered ready.
74     */
75    unsigned numTotalRegs;
76
77    /** The index of the zero register. */
78    PhysRegIndex zeroRegIdx;
79
80    /** The index of the FP zero register. */
81    PhysRegIndex fpZeroRegIdx;
82
83    bool isZeroReg(PhysRegIndex idx) const
84    {
85        return (idx == zeroRegIdx ||
86                (THE_ISA == ALPHA_ISA && idx == fpZeroRegIdx));
87    }
88
89  public:
90    /** Constructs a scoreboard.
91     *  @param _numPhysicalRegs Number of physical registers.
92     *  @param _numMiscRegs Number of miscellaneous registers.
93     *  @param _zeroRegIdx Index of the zero register.
94     *  @param _fpZeroRegIdx Index of the FP zero register (if any, currently
95     *                       used only for Alpha).
96     */
97    Scoreboard(const std::string &_my_name,
98               unsigned _numPhysicalRegs,
99               unsigned _numMiscRegs,
100               PhysRegIndex _zeroRegIdx,
101               PhysRegIndex _fpZeroRegIdx);
102
103    /** Destructor. */
104    ~Scoreboard() {}
105
106    /** Returns the name of the scoreboard. */
107    std::string name() const { return _name; };
108
109    /** Checks if the register is ready. */
110    bool getReg(PhysRegIndex reg_idx) const
111    {
112        assert(reg_idx < numTotalRegs);
113
114        if (reg_idx >= numPhysRegs) {
115            // misc regs are always ready
116            return true;
117        }
118
119        bool ready = regScoreBoard[reg_idx];
120
121        if (isZeroReg(reg_idx))
122            assert(ready);
123
124        return ready;
125    }
126
127    /** Sets the register as ready. */
128    void setReg(PhysRegIndex reg_idx)
129    {
130        assert(reg_idx < numTotalRegs);
131
132        if (reg_idx >= numPhysRegs) {
133            // misc regs are always ready, ignore attempts to change that
134            return;
135        }
136
137        DPRINTF(Scoreboard, "Setting reg %i as ready\n", reg_idx);
138
139        assert(reg_idx < numTotalRegs);
140        regScoreBoard[reg_idx] = true;
141    }
142
143    /** Sets the register as not ready. */
144    void unsetReg(PhysRegIndex reg_idx)
145    {
146        assert(reg_idx < numTotalRegs);
147
148        if (reg_idx >= numPhysRegs) {
149            // misc regs are always ready, ignore attempts to change that
150            return;
151        }
152
153        // zero reg should never be marked unready
154        if (isZeroReg(reg_idx))
155            return;
156
157        regScoreBoard[reg_idx] = false;
158    }
159
160};
161
162#endif
163