store_set.cc revision 2632:1bb2f91485ea 
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#include "base/trace.hh"
30#include "cpu/o3/store_set.hh"
31
32StoreSet::StoreSet(int _SSIT_size, int _LFST_size)
33    : SSIT_size(_SSIT_size), LFST_size(_LFST_size)
34{
35    DPRINTF(StoreSet, "StoreSet: Creating store set object.\n");
36    DPRINTF(StoreSet, "StoreSet: SSIT size: %i, LFST size: %i.\n",
37            SSIT_size, LFST_size);
38
39    SSIT = new SSID[SSIT_size];
40
41    validSSIT.resize(SSIT_size);
42
43    for (int i = 0; i < SSIT_size; ++i)
44        validSSIT[i] = false;
45
46    LFST = new InstSeqNum[LFST_size];
47
48    validLFST.resize(LFST_size);
49
50    SSCounters = new int[LFST_size];
51
52    for (int i = 0; i < LFST_size; ++i)
53    {
54        validLFST[i] = false;
55        SSCounters[i] = 0;
56    }
57
58    index_mask = SSIT_size - 1;
59
60    offset_bits = 2;
61}
62
63void
64StoreSet::violation(Addr store_PC, Addr load_PC)
65{
66    int load_index = calcIndex(load_PC);
67    int store_index = calcIndex(store_PC);
68
69    assert(load_index < SSIT_size && store_index < SSIT_size);
70
71    bool valid_load_SSID = validSSIT[load_index];
72    bool valid_store_SSID = validSSIT[store_index];
73
74    if (!valid_load_SSID && !valid_store_SSID) {
75        // Calculate a new SSID here.
76        SSID new_set = calcSSID(load_PC);
77
78        validSSIT[load_index] = true;
79
80        SSIT[load_index] = new_set;
81
82        validSSIT[store_index] = true;
83
84        SSIT[store_index] = new_set;
85
86        assert(new_set < LFST_size);
87
88        SSCounters[new_set]++;
89
90
91        DPRINTF(StoreSet, "StoreSet: Neither load nor store had a valid "
92                "storeset, creating a new one: %i for load %#x, store %#x\n",
93                new_set, load_PC, store_PC);
94    } else if (valid_load_SSID && !valid_store_SSID) {
95        SSID load_SSID = SSIT[load_index];
96
97        validSSIT[store_index] = true;
98
99        SSIT[store_index] = load_SSID;
100
101        assert(load_SSID < LFST_size);
102
103        SSCounters[load_SSID]++;
104
105        DPRINTF(StoreSet, "StoreSet: Load had a valid store set.  Adding "
106                "store to that set: %i for load %#x, store %#x\n",
107                load_SSID, load_PC, store_PC);
108    } else if (!valid_load_SSID && valid_store_SSID) {
109        SSID store_SSID = SSIT[store_index];
110
111        validSSIT[load_index] = true;
112
113        SSIT[load_index] = store_SSID;
114
115        // Because we are having a load point to an already existing set,
116        // the size of the store set is not incremented.
117
118        DPRINTF(StoreSet, "StoreSet: Store had a valid store set: %i for "
119                "load %#x, store %#x\n",
120                store_SSID, load_PC, store_PC);
121    } else {
122        SSID load_SSID = SSIT[load_index];
123        SSID store_SSID = SSIT[store_index];
124
125        assert(load_SSID < LFST_size && store_SSID < LFST_size);
126
127        int load_SS_size = SSCounters[load_SSID];
128        int store_SS_size = SSCounters[store_SSID];
129
130        // If the load has the bigger store set, then assign the store
131        // to the same store set as the load.  Otherwise vice-versa.
132        if (load_SS_size > store_SS_size) {
133            SSIT[store_index] = load_SSID;
134
135            SSCounters[load_SSID]++;
136            SSCounters[store_SSID]--;
137
138            DPRINTF(StoreSet, "StoreSet: Load had bigger store set: %i; "
139                    "for load %#x, store %#x\n",
140                    load_SSID, load_PC, store_PC);
141        } else {
142            SSIT[load_index] = store_SSID;
143
144            SSCounters[store_SSID]++;
145            SSCounters[load_SSID]--;
146
147            DPRINTF(StoreSet, "StoreSet: Store had bigger store set: %i; "
148                    "for load %#x, store %#x\n",
149                    store_SSID, load_PC, store_PC);
150        }
151    }
152}
153
154void
155StoreSet::insertLoad(Addr load_PC, InstSeqNum load_seq_num)
156{
157    // Does nothing.
158    return;
159}
160
161void
162StoreSet::insertStore(Addr store_PC, InstSeqNum store_seq_num)
163{
164    int index = calcIndex(store_PC);
165
166    int store_SSID;
167
168    assert(index < SSIT_size);
169
170    if (!validSSIT[index]) {
171        // Do nothing if there's no valid entry.
172        return;
173    } else {
174        store_SSID = SSIT[index];
175
176        assert(store_SSID < LFST_size);
177
178        // Update the last store that was fetched with the current one.
179        LFST[store_SSID] = store_seq_num;
180
181        validLFST[store_SSID] = 1;
182
183        DPRINTF(StoreSet, "Store %#x updated the LFST, SSID: %i\n",
184                store_PC, store_SSID);
185    }
186}
187
188InstSeqNum
189StoreSet::checkInst(Addr PC)
190{
191    int index = calcIndex(PC);
192
193    int inst_SSID;
194
195    assert(index < SSIT_size);
196
197    if (!validSSIT[index]) {
198        DPRINTF(StoreSet, "Inst %#x with index %i had no SSID\n",
199                PC, index);
200
201        // Return 0 if there's no valid entry.
202        return 0;
203    } else {
204        inst_SSID = SSIT[index];
205
206        assert(inst_SSID < LFST_size);
207
208        if (!validLFST[inst_SSID]) {
209
210            DPRINTF(StoreSet, "Inst %#x with index %i and SSID %i had no "
211                    "dependency\n", PC, index, inst_SSID);
212
213            return 0;
214        } else {
215            DPRINTF(StoreSet, "Inst %#x with index %i and SSID %i had LFST "
216                    "inum of %i\n", PC, index, inst_SSID, LFST[inst_SSID]);
217
218            return LFST[inst_SSID];
219        }
220    }
221}
222
223void
224StoreSet::issued(Addr issued_PC, InstSeqNum issued_seq_num, bool is_store)
225{
226    // This only is updated upon a store being issued.
227    if (!is_store) {
228        return;
229    }
230
231    int index = calcIndex(issued_PC);
232
233    int store_SSID;
234
235    assert(index < SSIT_size);
236
237    // Make sure the SSIT still has a valid entry for the issued store.
238    if (!validSSIT[index]) {
239        return;
240    }
241
242    store_SSID = SSIT[index];
243
244    assert(store_SSID < LFST_size);
245
246    // If the last fetched store in the store set refers to the store that
247    // was just issued, then invalidate the entry.
248    if (validLFST[store_SSID] && LFST[store_SSID] == issued_seq_num) {
249        DPRINTF(StoreSet, "StoreSet: store invalidated itself in LFST.\n");
250        validLFST[store_SSID] = false;
251    }
252}
253
254void
255StoreSet::squash(InstSeqNum squashed_num)
256{
257    // Not really sure how to do this well.
258    // Generally this is small enough that it should be okay; short circuit
259    // evaluation should take care of invalid entries.
260
261    DPRINTF(StoreSet, "StoreSet: Squashing until inum %i\n",
262            squashed_num);
263
264    for (int i = 0; i < LFST_size; ++i) {
265        if (validLFST[i] && LFST[i] < squashed_num) {
266            validLFST[i] = false;
267        }
268    }
269}
270
271void
272StoreSet::clear()
273{
274    for (int i = 0; i < SSIT_size; ++i) {
275        validSSIT[i] = false;
276    }
277
278    for (int i = 0; i < LFST_size; ++i) {
279        validLFST[i] = false;
280    }
281}
282
283