free_list.hh revision 2107 
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
29#ifndef __CPU_O3_CPU_FREE_LIST_HH__
30#define __CPU_O3_CPU_FREE_LIST_HH__
31
32#include <iostream>
33#include <queue>
34
35#include "arch/isa_traits.hh"
36#include "base/trace.hh"
37#include "base/traceflags.hh"
38#include "cpu/o3/comm.hh"
39
40/**
41 * FreeList class that simply holds the list of free integer and floating
42 * point registers.  Can request for a free register of either type, and
43 * also send back free registers of either type.  This is a very simple
44 * class, but it should be sufficient for most implementations.  Like all
45 * other classes, it assumes that the indices for the floating point
46 * registers starts after the integer registers end.  Hence the variable
47 * numPhysicalIntRegs is logically equivalent to the baseFP dependency.
48 * Note that
49 * while this most likely should be called FreeList, the name "FreeList"
50 * is used in a typedef within the CPU Policy, and therefore no class
51 * can be named simply "FreeList".
52 * @todo: Give a better name to the base FP dependency.
53 */
54class SimpleFreeList
55{
56  private:
57    /** The list of free integer registers. */
58    std::queue<PhysRegIndex> freeIntRegs;
59
60    /** The list of free floating point registers. */
61    std::queue<PhysRegIndex> freeFloatRegs;
62
63    /** Number of logical integer registers. */
64    int numLogicalIntRegs;
65
66    /** Number of physical integer registers. */
67    int numPhysicalIntRegs;
68
69    /** Number of logical floating point registers. */
70    int numLogicalFloatRegs;
71
72    /** Number of physical floating point registers. */
73    int numPhysicalFloatRegs;
74
75    /** Total number of physical registers. */
76    int numPhysicalRegs;
77
78    /** DEBUG stuff below. */
79    std::vector<int> freeIntRegsScoreboard;
80
81    std::vector<bool> freeFloatRegsScoreboard;
82
83  public:
84    SimpleFreeList(unsigned _numLogicalIntRegs,
85                   unsigned _numPhysicalIntRegs,
86                   unsigned _numLogicalFloatRegs,
87                   unsigned _numPhysicalFloatRegs);
88
89    inline PhysRegIndex getIntReg();
90
91    inline PhysRegIndex getFloatReg();
92
93    inline void addReg(PhysRegIndex freed_reg);
94
95    inline void addIntReg(PhysRegIndex freed_reg);
96
97    inline void addFloatReg(PhysRegIndex freed_reg);
98
99    bool hasFreeIntRegs()
100    { return !freeIntRegs.empty(); }
101
102    bool hasFreeFloatRegs()
103    { return !freeFloatRegs.empty(); }
104
105    int numFreeIntRegs()
106    { return freeIntRegs.size(); }
107
108    int numFreeFloatRegs()
109    { return freeFloatRegs.size(); }
110};
111
112inline PhysRegIndex
113SimpleFreeList::getIntReg()
114{
115    DPRINTF(Rename, "FreeList: Trying to get free integer register.\n");
116    if (freeIntRegs.empty()) {
117        panic("No free integer registers!");
118    }
119
120    PhysRegIndex free_reg = freeIntRegs.front();
121
122    freeIntRegs.pop();
123
124    // DEBUG
125    assert(freeIntRegsScoreboard[free_reg]);
126    freeIntRegsScoreboard[free_reg] = 0;
127
128    return(free_reg);
129}
130
131inline PhysRegIndex
132SimpleFreeList::getFloatReg()
133{
134    DPRINTF(Rename, "FreeList: Trying to get free float register.\n");
135    if (freeFloatRegs.empty()) {
136        panic("No free integer registers!");
137    }
138
139    PhysRegIndex free_reg = freeFloatRegs.front();
140
141    freeFloatRegs.pop();
142
143    // DEBUG
144    assert(freeFloatRegsScoreboard[free_reg]);
145    freeFloatRegsScoreboard[free_reg] = 0;
146
147    return(free_reg);
148}
149
150inline void
151SimpleFreeList::addReg(PhysRegIndex freed_reg)
152{
153    DPRINTF(Rename, "Freelist: Freeing register %i.\n", freed_reg);
154    //Might want to add in a check for whether or not this register is
155    //already in there.  A bit vector or something similar would be useful.
156    if (freed_reg < numPhysicalIntRegs) {
157        freeIntRegs.push(freed_reg);
158
159        // DEBUG
160        assert(freeIntRegsScoreboard[freed_reg] == false);
161        freeIntRegsScoreboard[freed_reg] = 1;
162    } else if (freed_reg < numPhysicalRegs) {
163        freeFloatRegs.push(freed_reg);
164
165        // DEBUG
166        assert(freeFloatRegsScoreboard[freed_reg] == false);
167        freeFloatRegsScoreboard[freed_reg] = 1;
168    }
169}
170
171inline void
172SimpleFreeList::addIntReg(PhysRegIndex freed_reg)
173{
174    DPRINTF(Rename, "Freelist: Freeing int register %i.\n", freed_reg);
175
176    // DEBUG
177    assert(!freeIntRegsScoreboard[freed_reg]);
178    freeIntRegsScoreboard[freed_reg] = 1;
179
180    freeIntRegs.push(freed_reg);
181}
182
183inline void
184SimpleFreeList::addFloatReg(PhysRegIndex freed_reg)
185{
186    DPRINTF(Rename, "Freelist: Freeing float register %i.\n", freed_reg);
187
188    // DEBUG
189    assert(!freeFloatRegsScoreboard[freed_reg]);
190    freeFloatRegsScoreboard[freed_reg] = 1;
191
192    freeFloatRegs.push(freed_reg);
193}
194
195#endif // __CPU_O3_CPU_FREE_LIST_HH__
196