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/intmath.hh"
32#include "base/trace.hh"
33#include "cpu/pred/btb.hh"
34
35DefaultBTB::DefaultBTB(unsigned _numEntries,
36 unsigned _tagBits,
37 unsigned _instShiftAmt)
38 : numEntries(_numEntries),
39 tagBits(_tagBits),
40 instShiftAmt(_instShiftAmt)
41{
42 DPRINTF(Fetch, "BTB: Creating BTB object.\n");
43
44 if (!isPowerOf2(numEntries)) {
45 fatal("BTB entries is not a power of 2!");
46 }
47
48 btb.resize(numEntries);
49
| 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/intmath.hh"
32#include "base/trace.hh"
33#include "cpu/pred/btb.hh"
34
35DefaultBTB::DefaultBTB(unsigned _numEntries,
36 unsigned _tagBits,
37 unsigned _instShiftAmt)
38 : numEntries(_numEntries),
39 tagBits(_tagBits),
40 instShiftAmt(_instShiftAmt)
41{
42 DPRINTF(Fetch, "BTB: Creating BTB object.\n");
43
44 if (!isPowerOf2(numEntries)) {
45 fatal("BTB entries is not a power of 2!");
46 }
47
48 btb.resize(numEntries);
49
|
65 btb[i].valid = false;
66 }
67}
68
69inline
70unsigned
71DefaultBTB::getIndex(const Addr &inst_PC)
72{
73 // Need to shift PC over by the word offset.
74 return (inst_PC >> instShiftAmt) & idxMask;
75}
76
77inline
78Addr
79DefaultBTB::getTag(const Addr &inst_PC)
80{
81 return (inst_PC >> tagShiftAmt) & tagMask;
82}
83
84bool
85DefaultBTB::valid(const Addr &inst_PC, ThreadID tid)
86{
87 unsigned btb_idx = getIndex(inst_PC);
88
89 Addr inst_tag = getTag(inst_PC);
90
91 assert(btb_idx < numEntries);
92
93 if (btb[btb_idx].valid
94 && inst_tag == btb[btb_idx].tag
95 && btb[btb_idx].tid == tid) {
96 return true;
97 } else {
98 return false;
99 }
100}
101
102// @todo Create some sort of return struct that has both whether or not the
103// address is valid, and also the address. For now will just use addr = 0 to
104// represent invalid entry.
105Addr
106DefaultBTB::lookup(const Addr &inst_PC, ThreadID tid)
107{
108 unsigned btb_idx = getIndex(inst_PC);
109
110 Addr inst_tag = getTag(inst_PC);
111
112 assert(btb_idx < numEntries);
113
114 if (btb[btb_idx].valid
115 && inst_tag == btb[btb_idx].tag
116 && btb[btb_idx].tid == tid) {
117 return btb[btb_idx].target;
118 } else {
119 return 0;
120 }
121}
122
123void
124DefaultBTB::update(const Addr &inst_PC, const Addr &target, ThreadID tid)
125{
126 unsigned btb_idx = getIndex(inst_PC);
127
128 assert(btb_idx < numEntries);
129
130 btb[btb_idx].tid = tid;
131 btb[btb_idx].valid = true;
132 btb[btb_idx].target = target;
133 btb[btb_idx].tag = getTag(inst_PC);
134}
| 65 btb[i].valid = false;
66 }
67}
68
69inline
70unsigned
71DefaultBTB::getIndex(const Addr &inst_PC)
72{
73 // Need to shift PC over by the word offset.
74 return (inst_PC >> instShiftAmt) & idxMask;
75}
76
77inline
78Addr
79DefaultBTB::getTag(const Addr &inst_PC)
80{
81 return (inst_PC >> tagShiftAmt) & tagMask;
82}
83
84bool
85DefaultBTB::valid(const Addr &inst_PC, ThreadID tid)
86{
87 unsigned btb_idx = getIndex(inst_PC);
88
89 Addr inst_tag = getTag(inst_PC);
90
91 assert(btb_idx < numEntries);
92
93 if (btb[btb_idx].valid
94 && inst_tag == btb[btb_idx].tag
95 && btb[btb_idx].tid == tid) {
96 return true;
97 } else {
98 return false;
99 }
100}
101
102// @todo Create some sort of return struct that has both whether or not the
103// address is valid, and also the address. For now will just use addr = 0 to
104// represent invalid entry.
105Addr
106DefaultBTB::lookup(const Addr &inst_PC, ThreadID tid)
107{
108 unsigned btb_idx = getIndex(inst_PC);
109
110 Addr inst_tag = getTag(inst_PC);
111
112 assert(btb_idx < numEntries);
113
114 if (btb[btb_idx].valid
115 && inst_tag == btb[btb_idx].tag
116 && btb[btb_idx].tid == tid) {
117 return btb[btb_idx].target;
118 } else {
119 return 0;
120 }
121}
122
123void
124DefaultBTB::update(const Addr &inst_PC, const Addr &target, ThreadID tid)
125{
126 unsigned btb_idx = getIndex(inst_PC);
127
128 assert(btb_idx < numEntries);
129
130 btb[btb_idx].tid = tid;
131 btb[btb_idx].valid = true;
132 btb[btb_idx].target = target;
133 btb[btb_idx].tag = getTag(inst_PC);
134}
|