free_list.hh revision 2292 
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_FREE_LIST_HH__
30#define __CPU_O3_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 while this most likely should be called FreeList, the name
49 * "FreeList" is used in a typedef within the CPU Policy, and therefore no
50 * class can be named simply "FreeList".
51 * @todo: Give a better name to the base FP dependency.
52 */
53class SimpleFreeList
54{
55  private:
56    /** The list of free integer registers. */
57    std::queue<PhysRegIndex> freeIntRegs;
58
59    /** The list of free floating point registers. */
60    std::queue<PhysRegIndex> freeFloatRegs;
61
62    /** Number of logical integer registers. */
63    int numLogicalIntRegs;
64
65    /** Number of physical integer registers. */
66    int numPhysicalIntRegs;
67
68    /** Number of logical floating point registers. */
69    int numLogicalFloatRegs;
70
71    /** Number of physical floating point registers. */
72    int numPhysicalFloatRegs;
73
74    /** Total number of physical registers. */
75    int numPhysicalRegs;
76
77  public:
78    /** Constructs a free list.
79     *  @param activeThreads Number of active threads.
80     *  @param _numLogicalIntRegs Number of logical integer registers.
81     *  @param _numPhysicalIntRegs Number of physical integer registers.
82     *  @param _numLogicalFloatRegs Number of logical fp registers.
83     *  @param _numPhysicalFloatRegs Number of physical fp registers.
84     */
85    SimpleFreeList(unsigned activeThreads,
86                   unsigned _numLogicalIntRegs,
87                   unsigned _numPhysicalIntRegs,
88                   unsigned _numLogicalFloatRegs,
89                   unsigned _numPhysicalFloatRegs);
90
91    /** Gives the name of the freelist. */
92    std::string name() const;
93
94    /** Gets a free integer register. */
95    inline PhysRegIndex getIntReg();
96
97    /** Gets a free fp register. */
98    inline PhysRegIndex getFloatReg();
99
100    /** Adds a register back to the free list. */
101    inline void addReg(PhysRegIndex freed_reg);
102
103    /** Adds an integer register back to the free list. */
104    inline void addIntReg(PhysRegIndex freed_reg);
105
106    /** Adds a fp register back to the free list. */
107    inline void addFloatReg(PhysRegIndex freed_reg);
108
109    /** Checks if there are any free integer registers. */
110    bool hasFreeIntRegs()
111    { return !freeIntRegs.empty(); }
112
113    /** Checks if there are any free fp registers. */
114    bool hasFreeFloatRegs()
115    { return !freeFloatRegs.empty(); }
116
117    /** Returns the number of free integer registers. */
118    int numFreeIntRegs()
119    { return freeIntRegs.size(); }
120
121    /** Returns the number of free fp registers. */
122    int numFreeFloatRegs()
123    { return freeFloatRegs.size(); }
124};
125
126inline PhysRegIndex
127SimpleFreeList::getIntReg()
128{
129    DPRINTF(FreeList, "Trying to get free integer register.\n");
130
131    if (freeIntRegs.empty()) {
132        panic("No free integer registers!");
133    }
134
135    PhysRegIndex free_reg = freeIntRegs.front();
136
137    freeIntRegs.pop();
138
139    return(free_reg);
140}
141
142inline PhysRegIndex
143SimpleFreeList::getFloatReg()
144{
145    DPRINTF(FreeList, "Trying to get free float register.\n");
146
147    if (freeFloatRegs.empty()) {
148        panic("No free integer registers!");
149    }
150
151    PhysRegIndex free_reg = freeFloatRegs.front();
152
153    freeFloatRegs.pop();
154
155    return(free_reg);
156}
157
158inline void
159SimpleFreeList::addReg(PhysRegIndex freed_reg)
160{
161    DPRINTF(FreeList,"Freeing register %i.\n", freed_reg);
162    //Might want to add in a check for whether or not this register is
163    //already in there.  A bit vector or something similar would be useful.
164    if (freed_reg < numPhysicalIntRegs) {
165        if (freed_reg != TheISA::ZeroReg)
166            freeIntRegs.push(freed_reg);
167    } else if (freed_reg < numPhysicalRegs) {
168        if (freed_reg != (TheISA::ZeroReg + numPhysicalIntRegs))
169            freeFloatRegs.push(freed_reg);
170    }
171}
172
173inline void
174SimpleFreeList::addIntReg(PhysRegIndex freed_reg)
175{
176    DPRINTF(FreeList,"Freeing int register %i.\n", freed_reg);
177
178    freeIntRegs.push(freed_reg);
179}
180
181inline void
182SimpleFreeList::addFloatReg(PhysRegIndex freed_reg)
183{
184    DPRINTF(FreeList,"Freeing float register %i.\n", freed_reg);
185
186    freeFloatRegs.push(freed_reg);
187}
188
189#endif // __CPU_O3_FREE_LIST_HH__
190