free_list.hh revision 14025 
1/*
2 * Copyright (c) 2016-2018 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
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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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/logging.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, [this](typename InputIt::value_type& reg) {
83            this->freeRegs.push(&reg);
84        });
85    }
86
87    /** Get the next available register from the free list */
88    PhysRegIdPtr getReg()
89    {
90        assert(!freeRegs.empty());
91        PhysRegIdPtr free_reg = freeRegs.front();
92        freeRegs.pop();
93        return free_reg;
94    }
95
96    /** Return the number of free registers on the list. */
97    unsigned numFreeRegs() const { return freeRegs.size(); }
98
99    /** True iff there are free registers on the list. */
100    bool hasFreeRegs() const { return !freeRegs.empty(); }
101};
102
103
104/**
105 * FreeList class that simply holds the list of free integer and floating
106 * point registers.  Can request for a free register of either type, and
107 * also send back free registers of either type.  This is a very simple
108 * class, but it should be sufficient for most implementations.  Like all
109 * other classes, it assumes that the indices for the floating point
110 * registers starts after the integer registers end.  Hence the variable
111 * numPhysicalIntRegs is logically equivalent to the baseFP dependency.
112 * Note that while this most likely should be called FreeList, the name
113 * "FreeList" is used in a typedef within the CPU Policy, and therefore no
114 * class can be named simply "FreeList".
115 * @todo: Give a better name to the base FP dependency.
116 */
117class UnifiedFreeList
118{
119  private:
120
121    /** The object name, for DPRINTF.  We have to declare this
122     *  explicitly because Scoreboard is not a SimObject. */
123    const std::string _name;
124
125    /** The list of free integer registers. */
126    SimpleFreeList intList;
127
128    /** The list of free floating point registers. */
129    SimpleFreeList floatList;
130
131    /** The following two are exclusive interfaces. */
132    /** @{ */
133    /** The list of free vector registers. */
134    SimpleFreeList vecList;
135
136    /** The list of free vector element registers. */
137    SimpleFreeList vecElemList;
138    /** @} */
139
140    /** The list of free predicate registers. */
141    SimpleFreeList predList;
142
143    /** The list of free condition-code registers. */
144    SimpleFreeList ccList;
145
146    /**
147     * The register file object is used only to distinguish integer
148     * from floating-point physical register indices.
149     */
150    PhysRegFile *regFile;
151
152    /*
153     * We give UnifiedRenameMap internal access so it can get at the
154     * internal per-class free lists and associate those with its
155     * per-class rename maps. See UnifiedRenameMap::init().
156     */
157    friend class UnifiedRenameMap;
158
159  public:
160    /** Constructs a free list.
161     *  @param _numPhysicalIntRegs Number of physical integer registers.
162     *  @param reservedIntRegs Number of integer registers already
163     *                         used by initial mappings.
164     *  @param _numPhysicalFloatRegs Number of physical fp registers.
165     *  @param reservedFloatRegs Number of fp registers already
166     *                           used by initial mappings.
167     */
168    UnifiedFreeList(const std::string &_my_name, PhysRegFile *_regFile);
169
170    /** Gives the name of the freelist. */
171    std::string name() const { return _name; };
172
173    /** Returns a pointer to the condition-code free list */
174    SimpleFreeList *getCCList() { return &ccList; }
175
176    /** Gets a free integer register. */
177    PhysRegIdPtr getIntReg() { return intList.getReg(); }
178
179    /** Gets a free fp register. */
180    PhysRegIdPtr getFloatReg() { return floatList.getReg(); }
181
182    /** Gets a free vector register. */
183    PhysRegIdPtr getVecReg() { return vecList.getReg(); }
184
185    /** Gets a free vector elemenet register. */
186    PhysRegIdPtr getVecElem() { return vecElemList.getReg(); }
187
188    /** Gets a free predicate register. */
189    PhysRegIdPtr getVecPredReg() { return predList.getReg(); }
190
191    /** Gets a free cc register. */
192    PhysRegIdPtr getCCReg() { return ccList.getReg(); }
193
194    /** Adds a register back to the free list. */
195    void addReg(PhysRegIdPtr freed_reg);
196
197    /** Adds a register back to the free list. */
198    template<class InputIt>
199    void addRegs(InputIt first, InputIt last);
200
201    /** Adds an integer register back to the free list. */
202    void addIntReg(PhysRegIdPtr freed_reg) { intList.addReg(freed_reg); }
203
204    /** Adds a fp register back to the free list. */
205    void addFloatReg(PhysRegIdPtr freed_reg) { floatList.addReg(freed_reg); }
206
207    /** Adds a vector register back to the free list. */
208    void addVecReg(PhysRegIdPtr freed_reg) { vecList.addReg(freed_reg); }
209
210    /** Adds a vector element register back to the free list. */
211    void addVecElem(PhysRegIdPtr freed_reg) {
212        vecElemList.addReg(freed_reg);
213    }
214
215    /** Adds a predicate register back to the free list. */
216    void addVecPredReg(PhysRegIdPtr freed_reg) { predList.addReg(freed_reg); }
217
218    /** Adds a cc register back to the free list. */
219    void addCCReg(PhysRegIdPtr freed_reg) { ccList.addReg(freed_reg); }
220
221    /** Checks if there are any free integer registers. */
222    bool hasFreeIntRegs() const { return intList.hasFreeRegs(); }
223
224    /** Checks if there are any free fp registers. */
225    bool hasFreeFloatRegs() const { return floatList.hasFreeRegs(); }
226
227    /** Checks if there are any free vector registers. */
228    bool hasFreeVecRegs() const { return vecList.hasFreeRegs(); }
229
230    /** Checks if there are any free vector registers. */
231    bool hasFreeVecElems() const { return vecElemList.hasFreeRegs(); }
232
233    /** Checks if there are any free predicate registers. */
234    bool hasFreeVecPredRegs() const { return predList.hasFreeRegs(); }
235
236    /** Checks if there are any free cc registers. */
237    bool hasFreeCCRegs() const { return ccList.hasFreeRegs(); }
238
239    /** Returns the number of free integer registers. */
240    unsigned numFreeIntRegs() const { return intList.numFreeRegs(); }
241
242    /** Returns the number of free fp registers. */
243    unsigned numFreeFloatRegs() const { return floatList.numFreeRegs(); }
244
245    /** Returns the number of free vector registers. */
246    unsigned numFreeVecRegs() const { return vecList.numFreeRegs(); }
247
248    /** Returns the number of free vector registers. */
249    unsigned numFreeVecElems() const { return vecElemList.numFreeRegs(); }
250
251    /** Returns the number of free predicate registers. */
252    unsigned numFreeVecPredRegs() const { return predList.numFreeRegs(); }
253
254    /** Returns the number of free cc registers. */
255    unsigned numFreeCCRegs() const { return ccList.numFreeRegs(); }
256};
257
258template<class InputIt>
259inline void
260UnifiedFreeList::addRegs(InputIt first, InputIt last)
261{
262    // Are there any registers to add?
263    if (first == last)
264        return;
265
266    panic_if((first != last) &&
267            first->classValue() != (last-1)->classValue(),
268            "Attempt to add mixed type regs: %s and %s",
269            first->className(),
270            (last-1)->className());
271    switch (first->classValue()) {
272        case IntRegClass:
273            intList.addRegs(first, last);
274            break;
275        case FloatRegClass:
276            floatList.addRegs(first, last);
277            break;
278        case VecRegClass:
279            vecList.addRegs(first, last);
280            break;
281        case VecElemClass:
282            vecElemList.addRegs(first, last);
283            break;
284        case VecPredRegClass:
285            predList.addRegs(first, last);
286            break;
287        case CCRegClass:
288            ccList.addRegs(first, last);
289            break;
290        default:
291            panic("Unexpected RegClass (%s)",
292                                   first->className());
293    }
294
295}
296
297inline void
298UnifiedFreeList::addReg(PhysRegIdPtr freed_reg)
299{
300    DPRINTF(FreeList,"Freeing register %i (%s).\n", freed_reg->index(),
301            freed_reg->className());
302    //Might want to add in a check for whether or not this register is
303    //already in there.  A bit vector or something similar would be useful.
304    switch (freed_reg->classValue()) {
305        case IntRegClass:
306            intList.addReg(freed_reg);
307            break;
308        case FloatRegClass:
309            floatList.addReg(freed_reg);
310            break;
311        case VecRegClass:
312            vecList.addReg(freed_reg);
313            break;
314        case VecElemClass:
315            vecElemList.addReg(freed_reg);
316            break;
317        case VecPredRegClass:
318            predList.addReg(freed_reg);
319            break;
320        case CCRegClass:
321            ccList.addReg(freed_reg);
322            break;
323        default:
324            panic("Unexpected RegClass (%s)",
325                                   freed_reg->className());
326    }
327
328    // These assert conditions ensure that the number of free
329    // registers are not more than the # of total Physical  Registers.
330    // If this were false, it would mean that registers
331    // have been freed twice, overflowing the free register
332    // pool and potentially crashing SMT workloads.
333    // ----
334    // Comment out for now so as to not potentially break
335    // CMP and single-threaded workloads
336    // ----
337    // assert(freeIntRegs.size() <= numPhysicalIntRegs);
338    // assert(freeFloatRegs.size() <= numPhysicalFloatRegs);
339}
340
341
342#endif // __CPU_O3_FREE_LIST_HH__
343