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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
#include <torch/csrc/jit/passes/liveness.h>
#include <torch/csrc/jit/ir/alias_analysis.h>
#include <torch/csrc/jit/ir/ir_views.h>
#include <torch/csrc/jit/passes/constant_pooling.h>
#include <memory>
namespace torch {
namespace jit {
// LivenessAnalyzer computes "bailout" liveness which is equivalent to
// "{LIVE_IN} or {GEN}" or "{LIVE_OUT} - {KILL}"
struct LivenessAnalyzer {
explicit LivenessAnalyzer(std::shared_ptr<Graph> graph)
: graph_(std::move(graph)), changed_(false) {}
std::unordered_map<Node*, std::vector<Value*>> run() {
std::vector<Node*> counters;
insertExplicitUsesOfLoopCounters(graph_->block(), counters);
// we implement the canonical fixed-point liveness
// the analysis is run until there are no more changes
// to liveness sets for each node
do {
changed_ = false;
processBlock(graph_->block(), SparseBitVector{});
} while (changed_);
removeCounterNodes(counters);
std::unordered_map<Node*, std::vector<Value*>> result;
for (const auto& e : liveness_sets_) {
result.insert({e.first, toValueVector(e.second)});
}
return result;
}
// temporary make loop counts live for the duration of the loop
// as they are needed by BailOuts in the loop
void insertExplicitUsesOfLoopCounters(
Block* b,
std::vector<Node*>& counters) {
for (auto it : b->nodes()) {
if (it->kind() == prim::Loop) {
LoopView lv(it);
WithInsertPoint guard(lv.bodyBlock());
auto ctc = graph_->create(prim::Store, {lv.currentTripCount()}, 0);
graph_->insertNode(ctc);
counters.push_back(ctc);
auto mtc = graph_->create(prim::Store, {lv.maxTripCount()}, 0);
graph_->insertNode(mtc);
counters.push_back(mtc);
}
for (auto ib : it->blocks()) {
insertExplicitUsesOfLoopCounters(ib, counters);
}
}
}
void removeCounterNodes(std::vector<Node*>& counters) {
for (auto n : counters) {
n->destroy();
}
}
void dump(
const std::unordered_map<Node*, std::vector<Value*>>& liveness_sets) {
std::cout << "Liveness info:\n";
for (auto e : liveness_sets) {
if (e.first->outputs().size() > 0) {
std::cout << e.first->outputs()[0]->debugName();
}
std::cout << " " << e.first->kind().toQualString();
std::cout << " = ";
dump(e.second);
std::cout << std::endl;
}
std::cout << "graph :\n";
graph_->dump();
}
void dump(const std::vector<Value*>& set) {
bool first = true;
std::cout << "[";
for (auto el : set) {
if (first) {
first = false;
} else {
std::cout << ", ";
}
std::cout << el->debugName() << "(" << el->unique() << ")";
}
std::cout << "]";
}
private:
SparseBitVector toSparseBitVector(at::ArrayRef<Value*> values) {
SparseBitVector sbv;
for (auto v : values) {
ids_to_values_[v->unique()] = v;
sbv.set(v->unique());
}
return sbv;
}
std::vector<Value*> toValueVector(const SparseBitVector& sbv) {
std::vector<Value*> vec;
for (auto id : sbv) {
vec.push_back(ids_to_values_[id]);
}
return vec;
}
SparseBitVector processBlock(Block* b, SparseBitVector liveness) {
// block outputs are the uses
auto block_outputs = toSparseBitVector(b->outputs());
liveness |= block_outputs;
SparseBitVector defs;
for (Node* it : b->nodes().reverse()) {
// kill outputs
liveness -= toSparseBitVector(it->outputs());
if (it->kind() == prim::Loop) {
LoopView lv(it);
// N.B. merge in changes from the loop header
auto loop_header = *lv.bodyBlock()->nodes().begin();
auto loop_block = liveness | liveness_sets_[loop_header];
loop_block = processBlock(lv.bodyBlock(), loop_block);
// loop block's inputs die outside loop's block
loop_block -= toSparseBitVector(lv.bodyBlock()->inputs());
liveness |= loop_block;
} else if (it->kind() == prim::If) {
IfView iv(it);
auto true_liveness = processBlock(iv.thenBlock(), liveness);
auto false_liveness = processBlock(iv.elseBlock(), liveness);
liveness |= true_liveness;
liveness |= false_liveness;
}
liveness |= toSparseBitVector(it->inputs());
// `|=` returns true if new bits were set in LHS
// after or/union with `liveness`
auto changed = liveness_sets_[it] |= liveness;
changed_ = changed_ | changed;
}
return liveness;
}
std::shared_ptr<Graph> graph_;
bool changed_;
std::map<Node*, SparseBitVector> liveness_sets_;
std::map<size_t, Value*> ids_to_values_;
};
std::unordered_map<Node*, std::vector<Value*>> BuildLivenessSets(
std::shared_ptr<Graph> graph) {
LivenessAnalyzer la(std::move(graph));
return la.run();
}
} // namespace jit
} // namespace torch
|
