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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
#!/usr/bin/env python3
# Copyright 2023 the V8 project authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can
# be found in the LICENSE file.
import sys
varint_mask = (1 << 5) - 1
varint_continue_bit = 1 << 5
varint_shift = 5
# We use the same VLQ-Base64 encoding as source maps, where each integer is
# first expressed as a variable length sequence of 6-bit items, and each item
# is then Base64-encoded individually.
# Index -> character
custom_base64_encoding = [0] * 64
# Character -> index
custom_base64_decoding = [-1] * 256
def fill_custom_base64_data():
base = 0
for i in range(ord('A'), ord('Z') + 1):
custom_base64_encoding[base + i - ord('A')] = chr(i)
base += 26
for i in range(ord('a'), ord('z') + 1):
custom_base64_encoding[base + i - ord('a')] = chr(i)
base += 26
for i in range(ord('0'), ord('9') + 1):
custom_base64_encoding[base + i - ord('0')] = chr(i)
base += 10
custom_base64_encoding[base] = '+'
custom_base64_encoding[base + 1] = '/'
for i in range(0, 64):
custom_base64_decoding[ord(custom_base64_encoding[i])] = i
fill_custom_base64_data()
def encode_varint(n):
# Encodes integer n as a varint the same way as in source maps.
# Add sign bit (the least significant bit):
if n < 0:
n = ((-n) << 1) | 1
else:
n = n << 1
# Each item represents varint_shift bits; the first item represents the
# least significant bits etc.
res = []
while n > 0:
current_item = n & varint_mask
n = n >> varint_shift
if n > 0:
current_item = current_item | varint_continue_bit
res.append(current_item)
return res
def custom_b64encode(items):
result = []
for item in items:
result.append(custom_base64_encoding[item])
return ''.join(result)
def custom_b64decode(s):
result = []
for c in s:
index = custom_base64_decoding[ord(c)]
if index < 0 or index > 64:
raise 'Corrupt data'
result.append(index)
return result
def encode_delta_varint_base64(start_positions):
bytes = []
prev_pos = 0
for p in start_positions:
bytes.extend(encode_varint(p - prev_pos))
prev_pos = p
return custom_b64encode(bytes)
def decode_varints(bytes):
ints = []
current = 0
byte_ix = 0
while byte_ix < len(bytes):
# Start parsing the new varint.
n = bytes[byte_ix]
byte_ix += 1
current = n & varint_mask
current_shift = 0
while n & varint_continue_bit != 0:
# Read another item.
if byte_ix >= len(bytes):
raise 'Corrupt data'
n = bytes[byte_ix]
byte_ix += 1
current_shift = current_shift + varint_shift
current = current | ((n & varint_mask) << current_shift)
if current & 1 != 0:
sign = -1
else:
sign = 1
current = sign * (current >> 1)
ints.append(current)
return ints
def decode_delta_varint_base64(comment):
bytes = custom_b64decode(comment)
deltas = decode_varints(bytes)
prev_pos = 0
positions = []
for d in deltas:
prev_pos += d
positions.append(prev_pos)
return positions
def generate_compile_hints(script_name_to_start_positions):
for script_name, start_positions in script_name_to_start_positions.items():
start_positions = list(start_positions)
start_positions.sort()
print(script_name)
magic_comment = encode_delta_varint_base64(start_positions)
back = decode_delta_varint_base64(magic_comment)
if start_positions != back:
print('Decoding failed!')
exit(1)
print(f"//# functionsCalledOnLoad={magic_comment}\n")
def process_v8_log(filename):
script_id_to_name = {}
script_name_to_start_positions = {}
with open(filename, 'r') as log_file:
for line in log_file:
fields = line.strip().split(',')
if len(fields) >= 3:
if fields[0] == 'script-details':
script_id = int(fields[1])
script_name = fields[2]
script_id_to_name[script_id] = script_name
elif fields[0] == 'function' and fields[1] == 'parse-function':
script_id = int(fields[2])
start_position = int(fields[3])
script_name = script_id_to_name[script_id]
if script_name in script_name_to_start_positions:
script_name_to_start_positions[script_name].add(start_position)
else:
script_name_to_start_positions[script_name] = {start_position}
generate_compile_hints(script_name_to_start_positions)
def process_text(filename):
# Format:
# file1, pos1
# file2, pos2
# file1, pos1
# ...
script_name_to_start_positions = {}
with open(filename, 'r') as log_file:
for line in log_file:
fields = line.strip().split(',')
if len(fields) >= 2:
script_name = fields[0]
start_position = int(fields[1])
if script_name in script_name_to_start_positions:
script_name_to_start_positions[script_name].add(start_position)
else:
script_name_to_start_positions[script_name] = {start_position}
generate_compile_hints(script_name_to_start_positions)
def print_usage():
print(
'Usage: python3 generate-explicit-function-compile-hints.py --v8log v8.log'
)
print(
'or: python3 generate-explicit-function-compile-hints.py --text data.txt'
)
def main():
if len(sys.argv) < 3 or '--help' in sys.argv:
print_usage()
exit(1)
if sys.argv[1] == '--v8log':
process_v8_log(sys.argv[2])
elif sys.argv[1] == '--text':
process_text(sys.argv[2])
else:
print_usage()
exit(1)
if __name__ == '__main__':
main()
|
