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
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package callgraph
import "golang.org/x/tools/go/ssa"
// This file provides various utilities over call graphs, such as
// visitation and path search.
// CalleesOf returns a new set containing all direct callees of the
// caller node.
func CalleesOf(caller *Node) map[*Node]bool {
callees := make(map[*Node]bool)
for _, e := range caller.Out {
callees[e.Callee] = true
}
return callees
}
// GraphVisitEdges visits all the edges in graph g in depth-first order.
// The edge function is called for each edge in postorder. If it
// returns non-nil, visitation stops and GraphVisitEdges returns that
// value.
func GraphVisitEdges(g *Graph, edge func(*Edge) error) error {
seen := make(map[*Node]bool)
var visit func(n *Node) error
visit = func(n *Node) error {
if !seen[n] {
seen[n] = true
for _, e := range n.Out {
if err := visit(e.Callee); err != nil {
return err
}
if err := edge(e); err != nil {
return err
}
}
}
return nil
}
for _, n := range g.Nodes {
if err := visit(n); err != nil {
return err
}
}
return nil
}
// PathSearch finds an arbitrary path starting at node start and
// ending at some node for which isEnd() returns true. On success,
// PathSearch returns the path as an ordered list of edges; on
// failure, it returns nil.
func PathSearch(start *Node, isEnd func(*Node) bool) []*Edge {
stack := make([]*Edge, 0, 32)
seen := make(map[*Node]bool)
var search func(n *Node) []*Edge
search = func(n *Node) []*Edge {
if !seen[n] {
seen[n] = true
if isEnd(n) {
return stack
}
for _, e := range n.Out {
stack = append(stack, e) // push
if found := search(e.Callee); found != nil {
return found
}
stack = stack[:len(stack)-1] // pop
}
}
return nil
}
return search(start)
}
// DeleteSyntheticNodes removes from call graph g all nodes for
// functions that do not correspond to source syntax. For historical
// reasons, nodes for g.Root and package initializers are always
// kept.
//
// As nodes are removed, edges are created to preserve the
// reachability relation of the remaining nodes.
func (g *Graph) DeleteSyntheticNodes() {
// Measurements on the standard library and go.tools show that
// resulting graph has ~15% fewer nodes and 4-8% fewer edges
// than the input.
//
// Inlining a wrapper of in-degree m, out-degree n adds m*n
// and removes m+n edges. Since most wrappers are monomorphic
// (n=1) this results in a slight reduction. Polymorphic
// wrappers (n>1), e.g. from embedding an interface value
// inside a struct to satisfy some interface, cause an
// increase in the graph, but they seem to be uncommon.
// Hash all existing edges to avoid creating duplicates.
edges := make(map[Edge]bool)
for _, cgn := range g.Nodes {
for _, e := range cgn.Out {
edges[*e] = true
}
}
for fn, cgn := range g.Nodes {
if cgn == g.Root || isInit(cgn.Func) || fn.Syntax() != nil {
continue // keep
}
for _, eIn := range cgn.In {
for _, eOut := range cgn.Out {
newEdge := Edge{eIn.Caller, eIn.Site, eOut.Callee}
if edges[newEdge] {
continue // don't add duplicate
}
AddEdge(eIn.Caller, eIn.Site, eOut.Callee)
edges[newEdge] = true
}
}
g.DeleteNode(cgn)
}
}
func isInit(fn *ssa.Function) bool {
return fn.Pkg != nil && fn.Pkg.Func("init") == fn
}
// DeleteNode removes node n and its edges from the graph g.
// (NB: not efficient for batch deletion.)
func (g *Graph) DeleteNode(n *Node) {
n.deleteIns()
n.deleteOuts()
delete(g.Nodes, n.Func)
}
// deleteIns deletes all incoming edges to n.
func (n *Node) deleteIns() {
for _, e := range n.In {
removeOutEdge(e)
}
n.In = nil
}
// deleteOuts deletes all outgoing edges from n.
func (n *Node) deleteOuts() {
for _, e := range n.Out {
removeInEdge(e)
}
n.Out = nil
}
// removeOutEdge removes edge.Caller's outgoing edge 'edge'.
func removeOutEdge(edge *Edge) {
caller := edge.Caller
n := len(caller.Out)
for i, e := range caller.Out {
if e == edge {
// Replace it with the final element and shrink the slice.
caller.Out[i] = caller.Out[n-1]
caller.Out[n-1] = nil // aid GC
caller.Out = caller.Out[:n-1]
return
}
}
panic("edge not found: " + edge.String())
}
// removeInEdge removes edge.Callee's incoming edge 'edge'.
func removeInEdge(edge *Edge) {
caller := edge.Callee
n := len(caller.In)
for i, e := range caller.In {
if e == edge {
// Replace it with the final element and shrink the slice.
caller.In[i] = caller.In[n-1]
caller.In[n-1] = nil // aid GC
caller.In = caller.In[:n-1]
return
}
}
panic("edge not found: " + edge.String())
}
|
