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;

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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

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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__