store_set.cc revision 2665:a124942bacb8 
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 * Authors: Kevin Lim
29 */
30
31#include "base/trace.hh"
32#include "cpu/o3/store_set.hh"
33
34StoreSet::StoreSet(int _SSIT_size, int _LFST_size)
35    : SSIT_size(_SSIT_size), LFST_size(_LFST_size)
36{
37    DPRINTF(StoreSet, "StoreSet: Creating store set object.\n");
38    DPRINTF(StoreSet, "StoreSet: SSIT size: %i, LFST size: %i.\n",
39            SSIT_size, LFST_size);
40
41    SSIT = new SSID[SSIT_size];
42
43    validSSIT.resize(SSIT_size);
44
45    for (int i = 0; i < SSIT_size; ++i)
46        validSSIT[i] = false;
47
48    LFST = new InstSeqNum[LFST_size];
49
50    validLFST.resize(LFST_size);
51
52    SSCounters = new int[LFST_size];
53
54    for (int i = 0; i < LFST_size; ++i)
55    {
56        validLFST[i] = false;
57        SSCounters[i] = 0;
58    }
59
60    index_mask = SSIT_size - 1;
61
62    offset_bits = 2;
63}
64
65void
66StoreSet::violation(Addr store_PC, Addr load_PC)
67{
68    int load_index = calcIndex(load_PC);
69    int store_index = calcIndex(store_PC);
70
71    assert(load_index < SSIT_size && store_index < SSIT_size);
72
73    bool valid_load_SSID = validSSIT[load_index];
74    bool valid_store_SSID = validSSIT[store_index];
75
76    if (!valid_load_SSID && !valid_store_SSID) {
77        // Calculate a new SSID here.
78        SSID new_set = calcSSID(load_PC);
79
80        validSSIT[load_index] = true;
81
82        SSIT[load_index] = new_set;
83
84        validSSIT[store_index] = true;
85
86        SSIT[store_index] = new_set;
87
88        assert(new_set < LFST_size);
89
90        SSCounters[new_set]++;
91
92
93        DPRINTF(StoreSet, "StoreSet: Neither load nor store had a valid "
94                "storeset, creating a new one: %i for load %#x, store %#x\n",
95                new_set, load_PC, store_PC);
96    } else if (valid_load_SSID && !valid_store_SSID) {
97        SSID load_SSID = SSIT[load_index];
98
99        validSSIT[store_index] = true;
100
101        SSIT[store_index] = load_SSID;
102
103        assert(load_SSID < LFST_size);
104
105        SSCounters[load_SSID]++;
106
107        DPRINTF(StoreSet, "StoreSet: Load had a valid store set.  Adding "
108                "store to that set: %i for load %#x, store %#x\n",
109                load_SSID, load_PC, store_PC);
110    } else if (!valid_load_SSID && valid_store_SSID) {
111        SSID store_SSID = SSIT[store_index];
112
113        validSSIT[load_index] = true;
114
115        SSIT[load_index] = store_SSID;
116
117        // Because we are having a load point to an already existing set,
118        // the size of the store set is not incremented.
119
120        DPRINTF(StoreSet, "StoreSet: Store had a valid store set: %i for "
121                "load %#x, store %#x\n",
122                store_SSID, load_PC, store_PC);
123    } else {
124        SSID load_SSID = SSIT[load_index];
125        SSID store_SSID = SSIT[store_index];
126
127        assert(load_SSID < LFST_size && store_SSID < LFST_size);
128
129        int load_SS_size = SSCounters[load_SSID];
130        int store_SS_size = SSCounters[store_SSID];
131
132        // If the load has the bigger store set, then assign the store
133        // to the same store set as the load.  Otherwise vice-versa.
134        if (load_SS_size > store_SS_size) {
135            SSIT[store_index] = load_SSID;
136
137            SSCounters[load_SSID]++;
138            SSCounters[store_SSID]--;
139
140            DPRINTF(StoreSet, "StoreSet: Load had bigger store set: %i; "
141                    "for load %#x, store %#x\n",
142                    load_SSID, load_PC, store_PC);
143        } else {
144            SSIT[load_index] = store_SSID;
145
146            SSCounters[store_SSID]++;
147            SSCounters[load_SSID]--;
148
149            DPRINTF(StoreSet, "StoreSet: Store had bigger store set: %i; "
150                    "for load %#x, store %#x\n",
151                    store_SSID, load_PC, store_PC);
152        }
153    }
154}
155
156void
157StoreSet::insertLoad(Addr load_PC, InstSeqNum load_seq_num)
158{
159    // Does nothing.
160    return;
161}
162
163void
164StoreSet::insertStore(Addr store_PC, InstSeqNum store_seq_num)
165{
166    int index = calcIndex(store_PC);
167
168    int store_SSID;
169
170    assert(index < SSIT_size);
171
172    if (!validSSIT[index]) {
173        // Do nothing if there's no valid entry.
174        return;
175    } else {
176        store_SSID = SSIT[index];
177
178        assert(store_SSID < LFST_size);
179
180        // Update the last store that was fetched with the current one.
181        LFST[store_SSID] = store_seq_num;
182
183        validLFST[store_SSID] = 1;
184
185        DPRINTF(StoreSet, "Store %#x updated the LFST, SSID: %i\n",
186                store_PC, store_SSID);
187    }
188}
189
190InstSeqNum
191StoreSet::checkInst(Addr PC)
192{
193    int index = calcIndex(PC);
194
195    int inst_SSID;
196
197    assert(index < SSIT_size);
198
199    if (!validSSIT[index]) {
200        DPRINTF(StoreSet, "Inst %#x with index %i had no SSID\n",
201                PC, index);
202
203        // Return 0 if there's no valid entry.
204        return 0;
205    } else {
206        inst_SSID = SSIT[index];
207
208        assert(inst_SSID < LFST_size);
209
210        if (!validLFST[inst_SSID]) {
211
212            DPRINTF(StoreSet, "Inst %#x with index %i and SSID %i had no "
213                    "dependency\n", PC, index, inst_SSID);
214
215            return 0;
216        } else {
217            DPRINTF(StoreSet, "Inst %#x with index %i and SSID %i had LFST "
218                    "inum of %i\n", PC, index, inst_SSID, LFST[inst_SSID]);
219
220            return LFST[inst_SSID];
221        }
222    }
223}
224
225void
226StoreSet::issued(Addr issued_PC, InstSeqNum issued_seq_num, bool is_store)
227{
228    // This only is updated upon a store being issued.
229    if (!is_store) {
230        return;
231    }
232
233    int index = calcIndex(issued_PC);
234
235    int store_SSID;
236
237    assert(index < SSIT_size);
238
239    // Make sure the SSIT still has a valid entry for the issued store.
240    if (!validSSIT[index]) {
241        return;
242    }
243
244    store_SSID = SSIT[index];
245
246    assert(store_SSID < LFST_size);
247
248    // If the last fetched store in the store set refers to the store that
249    // was just issued, then invalidate the entry.
250    if (validLFST[store_SSID] && LFST[store_SSID] == issued_seq_num) {
251        DPRINTF(StoreSet, "StoreSet: store invalidated itself in LFST.\n");
252        validLFST[store_SSID] = false;
253    }
254}
255
256void
257StoreSet::squash(InstSeqNum squashed_num)
258{
259    // Not really sure how to do this well.
260    // Generally this is small enough that it should be okay; short circuit
261    // evaluation should take care of invalid entries.
262
263    DPRINTF(StoreSet, "StoreSet: Squashing until inum %i\n",
264            squashed_num);
265
266    for (int i = 0; i < LFST_size; ++i) {
267        if (validLFST[i] && LFST[i] < squashed_num) {
268            validLFST[i] = false;
269        }
270    }
271}
272
273void
274StoreSet::clear()
275{
276    for (int i = 0; i < SSIT_size; ++i) {
277        validSSIT[i] = false;
278    }
279
280    for (int i = 0; i < LFST_size; ++i) {
281        validLFST[i] = false;
282    }
283}
284
285