free_list.hh revision 1061 
1#ifndef __FREE_LIST_HH__
2#define __FREE_LIST_HH__
3
4#include <iostream>
5#include <queue>
6
7#include "arch/alpha/isa_traits.hh"
8#include "cpu/beta_cpu/comm.hh"
9#include "base/trace.hh"
10
11// Question: Do I even need the number of logical registers?
12// How to avoid freeing registers instantly?  Same with ROB entries.
13
14/**
15 * FreeList class that simply holds the list of free integer and floating
16 * point registers.  Can request for a free register of either type, and
17 * also send back free registers of either type.  This is a very simple
18 * class, but it should be sufficient for most implementations.  Like all
19 * other classes, it assumes that the indices for the floating point
20 * registers starts after the integer registers end.  Hence the variable
21 * numPhysicalIntRegs is logically equivalent to the baseFP dependency.
22 * Note that
23 * while this most likely should be called FreeList, the name "FreeList"
24 * is used in a typedef within the CPU Policy, and therefore no class
25 * can be named simply "FreeList".
26 * @todo: Give a better name to the base FP dependency.
27 */
28class SimpleFreeList
29{
30  public:
31
32  private:
33    /** The list of free integer registers. */
34    std::queue<PhysRegIndex> freeIntRegs;
35
36    /** The list of free floating point registers. */
37    std::queue<PhysRegIndex> freeFloatRegs;
38
39    /** Number of logical integer registers. */
40    int numLogicalIntRegs;
41
42    /** Number of physical integer registers. */
43    int numPhysicalIntRegs;
44
45    /** Number of logical floating point registers. */
46    int numLogicalFloatRegs;
47
48    /** Number of physical floating point registers. */
49    int numPhysicalFloatRegs;
50
51    /** Total number of physical registers. */
52    int numPhysicalRegs;
53
54    /** DEBUG stuff below. */
55    std::vector<int> freeIntRegsScoreboard;
56
57    std::vector<bool> freeFloatRegsScoreboard;
58
59  public:
60    SimpleFreeList(unsigned _numLogicalIntRegs,
61                   unsigned _numPhysicalIntRegs,
62                   unsigned _numLogicalFloatRegs,
63                   unsigned _numPhysicalFloatRegs);
64
65    PhysRegIndex getIntReg();
66
67    PhysRegIndex getFloatReg();
68
69    void addReg(PhysRegIndex freed_reg);
70
71    void addIntReg(PhysRegIndex freed_reg);
72
73    void addFloatReg(PhysRegIndex freed_reg);
74
75    bool hasFreeIntRegs()
76    { return !freeIntRegs.empty(); }
77
78    bool hasFreeFloatRegs()
79    { return !freeFloatRegs.empty(); }
80
81    int numFreeIntRegs()
82    { return freeIntRegs.size(); }
83
84    int numFreeFloatRegs()
85    { return freeFloatRegs.size(); }
86};
87
88inline PhysRegIndex
89SimpleFreeList::getIntReg()
90{
91    DPRINTF(Rename, "FreeList: Trying to get free integer register.\n");
92    if (freeIntRegs.empty()) {
93        panic("No free integer registers!");
94    }
95
96    PhysRegIndex free_reg = freeIntRegs.front();
97
98    freeIntRegs.pop();
99
100    // DEBUG
101    assert(freeIntRegsScoreboard[free_reg]);
102    freeIntRegsScoreboard[free_reg] = 0;
103
104    return(free_reg);
105}
106
107inline PhysRegIndex
108SimpleFreeList::getFloatReg()
109{
110    DPRINTF(Rename, "FreeList: Trying to get free float register.\n");
111    if (freeFloatRegs.empty()) {
112        panic("No free integer registers!");
113    }
114
115    PhysRegIndex free_reg = freeFloatRegs.front();
116
117    freeFloatRegs.pop();
118
119    // DEBUG
120    assert(freeFloatRegsScoreboard[free_reg]);
121    freeFloatRegsScoreboard[free_reg] = 0;
122
123    return(free_reg);
124}
125
126inline void
127SimpleFreeList::addReg(PhysRegIndex freed_reg)
128{
129    DPRINTF(Rename, "Freelist: Freeing register %i.\n", freed_reg);
130    //Might want to add in a check for whether or not this register is
131    //already in there.  A bit vector or something similar would be useful.
132    if (freed_reg < numPhysicalIntRegs) {
133        freeIntRegs.push(freed_reg);
134
135        // DEBUG
136        assert(freeIntRegsScoreboard[freed_reg] == false);
137        freeIntRegsScoreboard[freed_reg] = 1;
138    } else if (freed_reg < numPhysicalRegs) {
139        freeFloatRegs.push(freed_reg);
140
141        // DEBUG
142        assert(freeFloatRegsScoreboard[freed_reg] == false);
143        freeFloatRegsScoreboard[freed_reg] = 1;
144    }
145}
146
147inline void
148SimpleFreeList::addIntReg(PhysRegIndex freed_reg)
149{
150    DPRINTF(Rename, "Freelist: Freeing int register %i.\n", freed_reg);
151
152    // DEBUG
153    assert(!freeIntRegsScoreboard[freed_reg]);
154    freeIntRegsScoreboard[freed_reg] = 1;
155
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    freeIntRegs.push(freed_reg);
159}
160
161inline void
162SimpleFreeList::addFloatReg(PhysRegIndex freed_reg)
163{
164    DPRINTF(Rename, "Freelist: Freeing float register %i.\n", freed_reg);
165
166    // DEBUG
167    assert(!freeFloatRegsScoreboard[freed_reg]);
168    freeFloatRegsScoreboard[freed_reg] = 1;
169
170    //Might want to add in a check for whether or not this register is
171    //already in there.  A bit vector or something similar would be useful.
172    freeFloatRegs.push(freed_reg);
173}
174
175#endif // __FREE_LIST_HH__
176