mem_dep_unit_impl.hh revision 1061 
1
2#include <map>
3
4#include "cpu/beta_cpu/mem_dep_unit.hh"
5
6// Hack: dependence predictor sizes are hardcoded.
7template <class MemDepPred, class Impl>
8MemDepUnit<MemDepPred, Impl>::MemDepUnit(Params &params)
9    : depPred(4028, 128)
10{
11    DPRINTF(MemDepUnit, "MemDepUnit: Creating MemDepUnit object.\n");
12}
13
14template <class MemDepPred, class Impl>
15void
16MemDepUnit<MemDepPred, Impl>::insert(DynInstPtr &inst)
17{
18    InstSeqNum inst_seq_num = inst->seqNum;
19
20
21    InstSeqNum producing_store = depPred.checkInst(inst->readPC());
22
23    if (producing_store == 0 ||
24        dependencies.find(producing_store) == dependencies.end()) {
25        readyInsts.insert(inst_seq_num);
26    } else {
27        // If it's not already ready, then add it to the renamed
28        // list and the dependencies.
29        renamedInsts.insert(inst_seq_num);
30
31        dependencies[producing_store].push_back(inst_seq_num);
32    }
33
34    if (inst->isStore()) {
35        depPred.insertStore(inst->readPC(), inst_seq_num);
36
37        // Make sure this store isn't already in this list.
38        assert(dependencies.find(inst_seq_num) == dependencies.end());
39
40        // Put a dependency entry in at the store's sequence number.
41        // Uh, not sure how this works...I want to create an entry but
42        // I don't have anything to put into the value yet.
43        dependencies[inst_seq_num];
44    } else if (!inst->isLoad()) {
45        panic("MemDepUnit: Unknown type! (most likely a barrier).");
46    }
47}
48
49template <class MemDepPred, class Impl>
50bool
51MemDepUnit<MemDepPred, Impl>::readyToIssue(DynInstPtr &inst)
52{
53    InstSeqNum inst_seq_num = inst->seqNum;
54
55    if (readyInsts.find(inst_seq_num) == readyInsts.end()) {
56        return false;
57    } else {
58        return true;
59    }
60}
61
62template <class MemDepPred, class Impl>
63void
64MemDepUnit<MemDepPred, Impl>::issue(DynInstPtr &inst)
65{
66    assert(readyInsts.find(inst->seqNum) != readyInsts.end());
67
68    // Remove the instruction from the ready list.
69    readyInsts.erase(inst->seqNum);
70}
71
72template <class MemDepPred, class Impl>
73void
74MemDepUnit<MemDepPred, Impl>::wakeDependents(DynInstPtr &inst)
75{
76    // Wake any dependencies.
77    dep_it_t dep_it = dependencies.find(inst);
78
79    // If there's no entry, then return.  Really there should only be
80    // no entry if the instruction is a load.
81    if (dep_it == dependencies.end()) {
82        return;
83    }
84
85    assert(inst->isStore());
86
87    for(int i = 0; i < (*dep_it).second.size(); ++i ) {
88        InstSeqNum woken_inst = (*dep_it).second[i];
89
90        // Should we have reached instructions that are actually squashed,
91        // there will be no more useful instructions in this dependency
92        // list.  Break out early.
93        if (renamedInsts.find(woken_inst) == renamedInsts.end()) {
94            DPRINTF(MemDepUnit, "MemDepUnit: Dependents on inst PC %#x "
95                    "are squashed, starting at SN %i.  Breaking early.\n",
96                    inst->readPC(), woken_inst);
97            break;
98        }
99
100        // Remove it from the renamed instructions.
101        renamedInsts.erase(woken_inst);
102
103        // Add it to the ready list.
104        readyInsts.insert(woken_inst);
105    }
106
107    dependencies.erase(dep_it);
108}
109
110template <class MemDepPred, class Impl>
111void
112MemDepUnit<MemDepPred, Impl>::squash(const InstSeqNum &squashed_num)
113{
114
115    if (!renamedInsts.empty()) {
116        sn_it_t renamed_it = renamedInsts.end();
117
118        --renamed_it;
119
120        // Remove entries from the renamed list as long as we haven't reached
121        // the end and the entries continue to be younger than the squashed.
122        while (!renamedInsts.empty() &&
123               (*renamed_it) > squashed_num)
124        {
125            renamedInsts.erase(renamed_it--);
126        }
127    }
128
129    if (!readyInsts.empty()) {
130        sn_it_t ready_it = readyInsts.end();
131
132        --ready_it;
133
134        // Same for the ready list.
135        while (!readyInsts.empty() &&
136               (*ready_it) > squashed_num)
137        {
138            readyInsts.erase(ready_it--);
139        }
140    }
141
142    if (!dependencies.empty()) {
143        dep_it_t dep_it = dependencies.end();
144
145        --dep_it;
146
147        // Same for the dependencies list.
148        while (!dependencies.empty() &&
149               (*dep_it).first > squashed_num)
150        {
151            dependencies.erase(dep_it--);
152        }
153    }
154
155    // Tell the dependency predictor to squash as well.
156    depPred.squash(squashed_num);
157}
158
159template <class MemDepPred, class Impl>
160void
161MemDepUnit<MemDepPred, Impl>::violation(DynInstPtr &store_inst,
162                                        DynInstPtr &violating_load)
163{
164    // Tell the memory dependence unit of the violation.
165    depPred.violation(violating_load->readPC(), store_inst->readPC());
166}
167