free_list.hh revision 2665:a124942bacb8 
1/*
2 * Copyright (c) 2004-2005 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 * Authors: Kevin Lim
29 */
30
31#ifndef __CPU_O3_CPU_FREE_LIST_HH__
32#define __CPU_O3_CPU_FREE_LIST_HH__
33
34#include <iostream>
35#include <queue>
36
37#include "arch/isa_traits.hh"
38#include "base/trace.hh"
39#include "base/traceflags.hh"
40#include "cpu/o3/comm.hh"
41
42/**
43 * FreeList class that simply holds the list of free integer and floating
44 * point registers.  Can request for a free register of either type, and
45 * also send back free registers of either type.  This is a very simple
46 * class, but it should be sufficient for most implementations.  Like all
47 * other classes, it assumes that the indices for the floating point
48 * registers starts after the integer registers end.  Hence the variable
49 * numPhysicalIntRegs is logically equivalent to the baseFP dependency.
50 * Note that
51 * while this most likely should be called FreeList, the name "FreeList"
52 * is used in a typedef within the CPU Policy, and therefore no class
53 * can be named simply "FreeList".
54 * @todo: Give a better name to the base FP dependency.
55 */
56class SimpleFreeList
57{
58  private:
59    /** The list of free integer registers. */
60    std::queue<PhysRegIndex> freeIntRegs;
61
62    /** The list of free floating point registers. */
63    std::queue<PhysRegIndex> freeFloatRegs;
64
65    /** Number of logical integer registers. */
66    int numLogicalIntRegs;
67
68    /** Number of physical integer registers. */
69    int numPhysicalIntRegs;
70
71    /** Number of logical floating point registers. */
72    int numLogicalFloatRegs;
73
74    /** Number of physical floating point registers. */
75    int numPhysicalFloatRegs;
76
77    /** Total number of physical registers. */
78    int numPhysicalRegs;
79
80    /** DEBUG stuff below. */
81    std::vector<int> freeIntRegsScoreboard;
82
83    std::vector<bool> freeFloatRegsScoreboard;
84
85  public:
86    SimpleFreeList(unsigned _numLogicalIntRegs,
87                   unsigned _numPhysicalIntRegs,
88                   unsigned _numLogicalFloatRegs,
89                   unsigned _numPhysicalFloatRegs);
90
91    inline PhysRegIndex getIntReg();
92
93    inline PhysRegIndex getFloatReg();
94
95    inline void addReg(PhysRegIndex freed_reg);
96
97    inline void addIntReg(PhysRegIndex freed_reg);
98
99    inline void addFloatReg(PhysRegIndex freed_reg);
100
101    bool hasFreeIntRegs()
102    { return !freeIntRegs.empty(); }
103
104    bool hasFreeFloatRegs()
105    { return !freeFloatRegs.empty(); }
106
107    int numFreeIntRegs()
108    { return freeIntRegs.size(); }
109
110    int numFreeFloatRegs()
111    { return freeFloatRegs.size(); }
112};
113
114inline PhysRegIndex
115SimpleFreeList::getIntReg()
116{
117    DPRINTF(Rename, "FreeList: Trying to get free integer register.\n");
118    if (freeIntRegs.empty()) {
119        panic("No free integer registers!");
120    }
121
122    PhysRegIndex free_reg = freeIntRegs.front();
123
124    freeIntRegs.pop();
125
126    // DEBUG
127    assert(freeIntRegsScoreboard[free_reg]);
128    freeIntRegsScoreboard[free_reg] = 0;
129
130    return(free_reg);
131}
132
133inline PhysRegIndex
134SimpleFreeList::getFloatReg()
135{
136    DPRINTF(Rename, "FreeList: Trying to get free float register.\n");
137    if (freeFloatRegs.empty()) {
138        panic("No free integer registers!");
139    }
140
141    PhysRegIndex free_reg = freeFloatRegs.front();
142
143    freeFloatRegs.pop();
144
145    // DEBUG
146    assert(freeFloatRegsScoreboard[free_reg]);
147    freeFloatRegsScoreboard[free_reg] = 0;
148
149    return(free_reg);
150}
151
152inline void
153SimpleFreeList::addReg(PhysRegIndex freed_reg)
154{
155    DPRINTF(Rename, "Freelist: Freeing register %i.\n", freed_reg);
156    //Might want to add in a check for whether or not this register is
157    //already in there.  A bit vector or something similar would be useful.
158    if (freed_reg < numPhysicalIntRegs) {
159        freeIntRegs.push(freed_reg);
160
161        // DEBUG
162        assert(freeIntRegsScoreboard[freed_reg] == false);
163        freeIntRegsScoreboard[freed_reg] = 1;
164    } else if (freed_reg < numPhysicalRegs) {
165        freeFloatRegs.push(freed_reg);
166
167        // DEBUG
168        assert(freeFloatRegsScoreboard[freed_reg] == false);
169        freeFloatRegsScoreboard[freed_reg] = 1;
170    }
171}
172
173inline void
174SimpleFreeList::addIntReg(PhysRegIndex freed_reg)
175{
176    DPRINTF(Rename, "Freelist: Freeing int register %i.\n", freed_reg);
177
178    // DEBUG
179    assert(!freeIntRegsScoreboard[freed_reg]);
180    freeIntRegsScoreboard[freed_reg] = 1;
181
182    freeIntRegs.push(freed_reg);
183}
184
185inline void
186SimpleFreeList::addFloatReg(PhysRegIndex freed_reg)
187{
188    DPRINTF(Rename, "Freelist: Freeing float register %i.\n", freed_reg);
189
190    // DEBUG
191    assert(!freeFloatRegsScoreboard[freed_reg]);
192    freeFloatRegsScoreboard[freed_reg] = 1;
193
194    freeFloatRegs.push(freed_reg);
195}
196
197#endif // __CPU_O3_CPU_FREE_LIST_HH__
198