free_list.hh revision 12109 
1/*
2 * Copyright (c) 2016 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2004-2005 The Regents of The University of Michigan
15 * Copyright (c) 2013 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Kevin Lim
42 */
43
44#ifndef __CPU_O3_FREE_LIST_HH__
45#define __CPU_O3_FREE_LIST_HH__
46
47#include <iostream>
48#include <queue>
49#include <vector>
50
51#include "base/misc.hh"
52#include "base/trace.hh"
53#include "cpu/o3/comm.hh"
54#include "cpu/o3/regfile.hh"
55#include "debug/FreeList.hh"
56
57/**
58 * Free list for a single class of registers (e.g., integer
59 * or floating point).  Because the register class is implicitly
60 * determined by the rename map instance being accessed, all
61 * architectural register index parameters and values in this class
62 * are relative (e.g., %fp2 is just index 2).
63 */
64class SimpleFreeList
65{
66  private:
67
68    /** The actual free list */
69    std::queue<PhysRegIdPtr> freeRegs;
70
71  public:
72
73    SimpleFreeList() {};
74
75    /** Add a physical register to the free list */
76    void addReg(PhysRegIdPtr reg) { freeRegs.push(reg); }
77
78    /** Add physical registers to the free list */
79    template<class InputIt>
80    void
81    addRegs(InputIt first, InputIt last) {
82        std::for_each(first, last,
83            [this](const typename InputIt::value_type& reg) {
84                this->freeRegs.push(&reg);
85            });
86    }
87
88    /** Get the next available register from the free list */
89    PhysRegIdPtr getReg()
90    {
91        assert(!freeRegs.empty());
92        PhysRegIdPtr free_reg = freeRegs.front();
93        freeRegs.pop();
94        return free_reg;
95    }
96
97    /** Return the number of free registers on the list. */
98    unsigned numFreeRegs() const { return freeRegs.size(); }
99
100    /** True iff there are free registers on the list. */
101    bool hasFreeRegs() const { return !freeRegs.empty(); }
102};
103
104
105/**
106 * FreeList class that simply holds the list of free integer and floating
107 * point registers.  Can request for a free register of either type, and
108 * also send back free registers of either type.  This is a very simple
109 * class, but it should be sufficient for most implementations.  Like all
110 * other classes, it assumes that the indices for the floating point
111 * registers starts after the integer registers end.  Hence the variable
112 * numPhysicalIntRegs is logically equivalent to the baseFP dependency.
113 * Note that while this most likely should be called FreeList, the name
114 * "FreeList" is used in a typedef within the CPU Policy, and therefore no
115 * class can be named simply "FreeList".
116 * @todo: Give a better name to the base FP dependency.
117 */
118class UnifiedFreeList
119{
120  private:
121
122    /** The object name, for DPRINTF.  We have to declare this
123     *  explicitly because Scoreboard is not a SimObject. */
124    const std::string _name;
125
126    /** The list of free integer registers. */
127    SimpleFreeList intList;
128
129    /** The list of free floating point registers. */
130    SimpleFreeList floatList;
131
132    /** The following two are exclusive interfaces. */
133    /** @{ */
134    /** The list of free vector registers. */
135    SimpleFreeList vecList;
136
137    /** The list of free vector element registers. */
138    SimpleFreeList vecElemList;
139    /** @} */
140
141    /** The list of free condition-code registers. */
142    SimpleFreeList ccList;
143
144    /**
145     * The register file object is used only to distinguish integer
146     * from floating-point physical register indices.
147     */
148    PhysRegFile *regFile;
149
150    /*
151     * We give UnifiedRenameMap internal access so it can get at the
152     * internal per-class free lists and associate those with its
153     * per-class rename maps. See UnifiedRenameMap::init().
154     */
155    friend class UnifiedRenameMap;
156
157  public:
158    /** Constructs a free list.
159     *  @param _numPhysicalIntRegs Number of physical integer registers.
160     *  @param reservedIntRegs Number of integer registers already
161     *                         used by initial mappings.
162     *  @param _numPhysicalFloatRegs Number of physical fp registers.
163     *  @param reservedFloatRegs Number of fp registers already
164     *                           used by initial mappings.
165     */
166    UnifiedFreeList(const std::string &_my_name, PhysRegFile *_regFile);
167
168    /** Gives the name of the freelist. */
169    std::string name() const { return _name; };
170
171    /** Returns a pointer to the condition-code free list */
172    SimpleFreeList *getCCList() { return &ccList; }
173
174    /** Gets a free integer register. */
175    PhysRegIdPtr getIntReg() { return intList.getReg(); }
176
177    /** Gets a free fp register. */
178    PhysRegIdPtr getFloatReg() { return floatList.getReg(); }
179
180    /** Gets a free vector register. */
181    PhysRegIdPtr getVecReg() { return vecList.getReg(); }
182
183    /** Gets a free vector elemenet register. */
184    PhysRegIdPtr getVecElem() { return vecElemList.getReg(); }
185
186    /** Gets a free cc register. */
187    PhysRegIdPtr getCCReg() { return ccList.getReg(); }
188
189    /** Adds a register back to the free list. */
190    void addReg(PhysRegIdPtr freed_reg);
191
192    /** Adds a register back to the free list. */
193    template<class InputIt>
194    void addRegs(InputIt first, InputIt last);
195
196    /** Adds an integer register back to the free list. */
197    void addIntReg(PhysRegIdPtr freed_reg) { intList.addReg(freed_reg); }
198
199    /** Adds a fp register back to the free list. */
200    void addFloatReg(PhysRegIdPtr freed_reg) { floatList.addReg(freed_reg); }
201
202    /** Adds a vector register back to the free list. */
203    void addVecReg(PhysRegIdPtr freed_reg) { vecList.addReg(freed_reg); }
204
205    /** Adds a vector element register back to the free list. */
206    void addVecElem(PhysRegIdPtr freed_reg) {
207        vecElemList.addReg(freed_reg);
208    }
209
210    /** Adds a cc register back to the free list. */
211    void addCCReg(PhysRegIdPtr freed_reg) { ccList.addReg(freed_reg); }
212
213    /** Checks if there are any free integer registers. */
214    bool hasFreeIntRegs() const { return intList.hasFreeRegs(); }
215
216    /** Checks if there are any free fp registers. */
217    bool hasFreeFloatRegs() const { return floatList.hasFreeRegs(); }
218
219    /** Checks if there are any free vector registers. */
220    bool hasFreeVecRegs() const { return vecList.hasFreeRegs(); }
221
222    /** Checks if there are any free vector registers. */
223    bool hasFreeVecElems() const { return vecElemList.hasFreeRegs(); }
224
225    /** Checks if there are any free cc registers. */
226    bool hasFreeCCRegs() const { return ccList.hasFreeRegs(); }
227
228    /** Returns the number of free integer registers. */
229    unsigned numFreeIntRegs() const { return intList.numFreeRegs(); }
230
231    /** Returns the number of free fp registers. */
232    unsigned numFreeFloatRegs() const { return floatList.numFreeRegs(); }
233
234    /** Returns the number of free vector registers. */
235    unsigned numFreeVecRegs() const { return vecList.numFreeRegs(); }
236
237    /** Returns the number of free cc registers. */
238    unsigned numFreeCCRegs() const { return ccList.numFreeRegs(); }
239};
240
241template<class InputIt>
242inline void
243UnifiedFreeList::addRegs(InputIt first, InputIt last)
244{
245    // Are there any registers to add?
246    if (first == last)
247        return;
248
249    panic_if((first != last) &&
250            first->classValue() != (last-1)->classValue(),
251            "Attempt to add mixed type regs: %s and %s",
252            first->className(),
253            (last-1)->className());
254    switch (first->classValue()) {
255        case IntRegClass:
256            intList.addRegs(first, last);
257            break;
258        case FloatRegClass:
259            floatList.addRegs(first, last);
260            break;
261        case VecRegClass:
262            vecList.addRegs(first, last);
263            break;
264        case VecElemClass:
265            vecElemList.addRegs(first, last);
266            break;
267        case CCRegClass:
268            ccList.addRegs(first, last);
269            break;
270        default:
271            panic("Unexpected RegClass (%s)",
272                                   first->className());
273    }
274
275}
276
277inline void
278UnifiedFreeList::addReg(PhysRegIdPtr freed_reg)
279{
280    DPRINTF(FreeList,"Freeing register %i (%s).\n", freed_reg->index(),
281            freed_reg->className());
282    //Might want to add in a check for whether or not this register is
283    //already in there.  A bit vector or something similar would be useful.
284    switch (freed_reg->classValue()) {
285        case IntRegClass:
286            intList.addReg(freed_reg);
287            break;
288        case FloatRegClass:
289            floatList.addReg(freed_reg);
290            break;
291        case VecRegClass:
292            vecList.addReg(freed_reg);
293            break;
294        case VecElemClass:
295            vecElemList.addReg(freed_reg);
296            break;
297        case CCRegClass:
298            ccList.addReg(freed_reg);
299            break;
300        default:
301            panic("Unexpected RegClass (%s)",
302                                   freed_reg->className());
303    }
304
305    // These assert conditions ensure that the number of free
306    // registers are not more than the # of total Physical  Registers.
307    // If this were false, it would mean that registers
308    // have been freed twice, overflowing the free register
309    // pool and potentially crashing SMT workloads.
310    // ----
311    // Comment out for now so as to not potentially break
312    // CMP and single-threaded workloads
313    // ----
314    // assert(freeIntRegs.size() <= numPhysicalIntRegs);
315    // assert(freeFloatRegs.size() <= numPhysicalFloatRegs);
316}
317
318
319#endif // __CPU_O3_FREE_LIST_HH__
320