1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
/*
* Copyright (c) 2014 The University of Wisconsin
*
* Copyright (c) 2006 INRIA (Institut National de Recherche en
* Informatique et en Automatique / French National Research Institute
* for Computer Science and Applied Mathematics)
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Authors: Vignyan Reddy, Dibakar Gope and Arthur Perais,
* from André Seznec's code.
*/
/* @file
* Implementation of a TAGE branch predictor
*/
#include "cpu/pred/tage.hh"
#include "base/intmath.hh"
#include "base/logging.hh"
#include "base/random.hh"
#include "base/trace.hh"
#include "debug/Fetch.hh"
#include "debug/Tage.hh"
TAGE::TAGE(const TAGEParams *params) : BPredUnit(params), tage(params->tage)
{
}
// PREDICTOR UPDATE
void
TAGE::update(ThreadID tid, Addr branch_pc, bool taken, void* bp_history,
bool squashed, const StaticInstPtr & inst, Addr corrTarget)
{
assert(bp_history);
TageBranchInfo *bi = static_cast<TageBranchInfo*>(bp_history);
TAGEBase::BranchInfo *tage_bi = bi->tageBranchInfo;
assert(corrTarget != MaxAddr);
if (squashed) {
// This restores the global history, then update it
// and recomputes the folded histories.
tage->squash(tid, taken, tage_bi, corrTarget);
return;
}
int nrand = random_mt.random<int>() & 3;
if (bi->tageBranchInfo->condBranch) {
DPRINTF(Tage, "Updating tables for branch:%lx; taken?:%d\n",
branch_pc, taken);
tage->updateStats(taken, bi->tageBranchInfo);
tage->condBranchUpdate(tid, branch_pc, taken, tage_bi, nrand,
corrTarget, bi->tageBranchInfo->tagePred);
}
// optional non speculative update of the histories
tage->updateHistories(tid, branch_pc, taken, tage_bi, false, inst,
corrTarget);
delete bi;
}
void
TAGE::squash(ThreadID tid, void *bp_history)
{
TageBranchInfo *bi = static_cast<TageBranchInfo*>(bp_history);
DPRINTF(Tage, "Deleting branch info: %lx\n", bi->tageBranchInfo->branchPC);
delete bi;
}
bool
TAGE::predict(ThreadID tid, Addr branch_pc, bool cond_branch, void* &b)
{
TageBranchInfo *bi = new TageBranchInfo(*tage);//nHistoryTables+1);
b = (void*)(bi);
return tage->tagePredict(tid, branch_pc, cond_branch, bi->tageBranchInfo);
}
bool
TAGE::lookup(ThreadID tid, Addr branch_pc, void* &bp_history)
{
bool retval = predict(tid, branch_pc, true, bp_history);
TageBranchInfo *bi = static_cast<TageBranchInfo*>(bp_history);
DPRINTF(Tage, "Lookup branch: %lx; predict:%d\n", branch_pc, retval);
tage->updateHistories(tid, branch_pc, retval, bi->tageBranchInfo, true);
return retval;
}
void
TAGE::btbUpdate(ThreadID tid, Addr branch_pc, void* &bp_history)
{
TageBranchInfo *bi = static_cast<TageBranchInfo*>(bp_history);
tage->btbUpdate(tid, branch_pc, bi->tageBranchInfo);
}
void
TAGE::uncondBranch(ThreadID tid, Addr br_pc, void* &bp_history)
{
DPRINTF(Tage, "UnConditionalBranch: %lx\n", br_pc);
predict(tid, br_pc, false, bp_history);
TageBranchInfo *bi = static_cast<TageBranchInfo*>(bp_history);
tage->updateHistories(tid, br_pc, true, bi->tageBranchInfo, true);
}
TAGE*
TAGEParams::create()
{
return new TAGE(this);
}
|
