free_list.hh revision 2669 
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/misc.hh"
37#include "base/trace.hh"
38#include "base/traceflags.hh"
39#include "cpu/o3/comm.hh"
40
41/**
42 * FreeList class that simply holds the list of free integer and floating
43 * point registers.  Can request for a free register of either type, and
44 * also send back free registers of either type.  This is a very simple
45 * class, but it should be sufficient for most implementations.  Like all
46 * other classes, it assumes that the indices for the floating point
47 * registers starts after the integer registers end.  Hence the variable
48 * numPhysicalIntRegs is logically equivalent to the baseFP dependency.
49 * Note that while this most likely should be called FreeList, the name
50 * "FreeList" is used in a typedef within the CPU Policy, and therefore no
51 * class 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  public:
79    /** Constructs a free list.
80     *  @param activeThreads Number of active threads.
81     *  @param _numLogicalIntRegs Number of logical integer registers.
82     *  @param _numPhysicalIntRegs Number of physical integer registers.
83     *  @param _numLogicalFloatRegs Number of logical fp registers.
84     *  @param _numPhysicalFloatRegs Number of physical fp registers.
85     */
86    SimpleFreeList(unsigned activeThreads,
87                   unsigned _numLogicalIntRegs,
88                   unsigned _numPhysicalIntRegs,
89                   unsigned _numLogicalFloatRegs,
90                   unsigned _numPhysicalFloatRegs);
91
92    /** Gives the name of the freelist. */
93    std::string name() const;
94
95    /** Gets a free integer register. */
96    inline PhysRegIndex getIntReg();
97
98    /** Gets a free fp register. */
99    inline PhysRegIndex getFloatReg();
100
101    /** Adds a register back to the free list. */
102    inline void addReg(PhysRegIndex freed_reg);
103
104    /** Adds an integer register back to the free list. */
105    inline void addIntReg(PhysRegIndex freed_reg);
106
107    /** Adds a fp register back to the free list. */
108    inline void addFloatReg(PhysRegIndex freed_reg);
109
110    /** Checks if there are any free integer registers. */
111    bool hasFreeIntRegs()
112    { return !freeIntRegs.empty(); }
113
114    /** Checks if there are any free fp registers. */
115    bool hasFreeFloatRegs()
116    { return !freeFloatRegs.empty(); }
117
118    /** Returns the number of free integer registers. */
119    int numFreeIntRegs()
120    { return freeIntRegs.size(); }
121
122    /** Returns the number of free fp registers. */
123    int numFreeFloatRegs()
124    { return freeFloatRegs.size(); }
125};
126
127inline PhysRegIndex
128SimpleFreeList::getIntReg()
129{
130    DPRINTF(FreeList, "Trying to get free integer register.\n");
131
132    if (freeIntRegs.empty()) {
133        panic("No free integer registers!");
134    }
135
136    PhysRegIndex free_reg = freeIntRegs.front();
137
138    freeIntRegs.pop();
139
140    return(free_reg);
141}
142
143inline PhysRegIndex
144SimpleFreeList::getFloatReg()
145{
146    DPRINTF(FreeList, "Trying to get free float register.\n");
147
148    if (freeFloatRegs.empty()) {
149        panic("No free integer registers!");
150    }
151
152    PhysRegIndex free_reg = freeFloatRegs.front();
153
154    freeFloatRegs.pop();
155
156    return(free_reg);
157}
158
159inline void
160SimpleFreeList::addReg(PhysRegIndex freed_reg)
161{
162    DPRINTF(FreeList,"Freeing register %i.\n", freed_reg);
163    //Might want to add in a check for whether or not this register is
164    //already in there.  A bit vector or something similar would be useful.
165    if (freed_reg < numPhysicalIntRegs) {
166        if (freed_reg != TheISA::ZeroReg)
167            freeIntRegs.push(freed_reg);
168    } else if (freed_reg < numPhysicalRegs) {
169        if (freed_reg != (TheISA::ZeroReg + numPhysicalIntRegs))
170            freeFloatRegs.push(freed_reg);
171    }
172}
173
174inline void
175SimpleFreeList::addIntReg(PhysRegIndex freed_reg)
176{
177    DPRINTF(FreeList,"Freeing int register %i.\n", freed_reg);
178
179    freeIntRegs.push(freed_reg);
180}
181
182inline void
183SimpleFreeList::addFloatReg(PhysRegIndex freed_reg)
184{
185    DPRINTF(FreeList,"Freeing float register %i.\n", freed_reg);
186
187    freeFloatRegs.push(freed_reg);
188}
189
190#endif // __CPU_O3_FREE_LIST_HH__
191