-
-
Notifications
You must be signed in to change notification settings - Fork 1.6k
/
line_numbers.cr
392 lines (342 loc) · 13.1 KB
/
line_numbers.cr
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
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
module Crystal
module DWARF
# :nodoc:
#
# Standard Line Number opcodes.
enum LNS : UInt8
Copy = 1
AdvancePc = 2
AdvanceLine = 3
SetFile = 4
SetColumn = 5
NegateStmt = 6
SetBasicBlock = 7
ConstAddPc = 8
FixedAdvancePc = 9
SetPrologueEnd = 10
SetEpiloqueBegin = 11
SetIsa = 12
end
# :nodoc:
#
# Extended Line Number opcodes.
enum LNE : UInt8
EndSequence = 1
SetAddress = 2
DefineFile = 3
SetDiscriminator = 4
end
# DWARF Line Numbers parser. Supports DWARF versions 2, 3 and 4.
#
# Usually located in the `.debug_line` section of ELF executables, or the
# `__debug_line` section of Mach-O files.
#
# Documentation:
# - [DWARF2](http://dwarfstd.org/doc/dwarf-2.0.0.pdf) section 6.2
# - [DWARF3](http://dwarfstd.org/doc/Dwarf3.pdf) section 6.2
# - [DWARF4](http://dwarfstd.org/doc/DWARF4.pdf) section 6.2
struct LineNumbers
# :nodoc:
#
# The state machine registers used to decompress the line number
# sequences.
struct Register
# The Program Counter (PC) value corresponding to a machine instruction
# generated by the compiler.
property address : UInt64
# The index of an operation inside a Very Long Instruction Word (VLIW)
# instruction. Together with `address` they reference an individual
# operation.
property op_index : UInt32
# Source file for the instruction.
property file : UInt32
# Line number within the source file. Starting at 1; the value 0 means
# that the instruction can't be attributed to any source line.
property line : UInt32
# Column number within the source file. Starting at 1; the value 0 means
# that a statement begins at the "left edge" of the line.
property column : UInt32
# Recommended breakpoint location.
property is_stmt : Bool
# Indicates that the instruction is the beginning of a basic block.
property basic_block : Bool
# Terminates a sequence of lines. Other information in the same row (of
# the decoded matrix) isn't meaningful.
property end_sequence : Bool
# Indicates the instruction is one where execution should be
# suspended (for an entry breakpoint).
property prologue_end : Bool
# Indicates the instruction is one where execution should be
# suspended (for an exit breakpoint).
property epilogue_begin : Bool
# Applicable Instruction Set Architecture for the instruction.
property isa : UInt32
# Identifies the block to which the instruction belongs.
property discriminator : UInt32
def initialize(@is_stmt)
@address = 0_u64
@op_index = 0_u32
@file = 1_u32
@line = 1_u32
@column = 0_u32
@basic_block = false
@end_sequence = false
@prologue_end = false
@epilogue_begin = false
@isa = 0_u32
@discriminator = 0_u32
end
def reset
@basic_block = false
@prologue_end = false
@epilogue_begin = false
@discriminator = 0_u32
end
end
# The decoded line number information for an instruction.
record Row,
address : UInt64,
op_index : UInt32,
directory : String,
file : String,
line : Int32,
column : Int32,
end_sequence : Bool
# :nodoc:
#
# An individual compressed sequence.
struct Sequence
property! offset : LibC::OffT
property! unit_length : UInt32
property! version : UInt16
property! header_length : UInt32 # FIXME: UInt64 for DWARF64 (uncommon)
property! minimum_instruction_length : UInt8
property maximum_operations_per_instruction : UInt8
property! default_is_stmt : Bool
property! line_base : Int8
property! line_range : UInt8
property! opcode_base : UInt8
# An array of how many args an array. Starts at 1 because 0 means an
# extended opcode.
getter standard_opcode_lengths
# An array of directory names. Starts at 1; 0 means that the information
# is missing.
getter include_directories
# An array of file names. Starts at 1; 0 means that the information is
# missing.
getter file_names
def initialize
@maximum_operations_per_instruction = 1_u8
@include_directories = [""]
@file_names = [{"", 0, 0, 0}]
@standard_opcode_lengths = [0_u8]
end
# Returns the unit length, adding the size of the `unit_length`.
def total_length
unit_length + sizeof(typeof(unit_length))
end
end
# Matrix of decompressed `Row` to search line number informations from the
# address of an instruction.
#
# The matrix contains indexed references to `directories` and `files` to
# reduce the memory usage of repeating a String many times.
getter matrix : Array(Array(Row))
@offset : LibC::OffT
def initialize(@io : IO::FileDescriptor, size, @base_address : LibC::SizeT = 0)
@offset = @io.tell
@matrix = Array(Array(Row)).new
decode_sequences(size)
end
# Returns the `Row` for the given Program Counter (PC) address if found.
def find(address)
matrix.each do |rows|
if row = rows.first?
next if address < row.address
end
if row = rows.last?
next if address > row.address
end
rows.each_with_index do |current_row, index|
if current_row.address == address
return current_row
end
if address < current_row.address
if previous_row = rows[index - 1]?
return previous_row
end
end
end
end
nil
end
# Decodes the compressed matrix of addresses to line numbers.
private def decode_sequences(size)
while true
pos = @io.tell
offset = pos - @offset
break unless offset < size
sequence = Sequence.new
sequence.offset = offset
sequence.unit_length = @io.read_bytes(UInt32)
sequence.version = @io.read_bytes(UInt16)
sequence.header_length = @io.read_bytes(UInt32)
sequence.minimum_instruction_length = @io.read_byte.not_nil!
if sequence.version >= 4
sequence.maximum_operations_per_instruction = @io.read_byte.not_nil!
end
sequence.default_is_stmt = @io.read_byte.not_nil! == 1
sequence.line_base = @io.read_bytes(Int8)
sequence.line_range = @io.read_byte.not_nil!
sequence.opcode_base = @io.read_byte.not_nil!
read_opcodes(sequence)
read_directory_table(sequence)
read_filename_table(sequence)
if @io.tell - @offset < sequence.offset + sequence.total_length
read_statement_program(sequence)
end
end
end
private def read_opcodes(sequence)
1.upto(sequence.opcode_base - 1) do
sequence.standard_opcode_lengths << @io.read_byte.not_nil!
end
end
private def read_directory_table(sequence)
loop do
name = @io.gets('\0', chomp: true).to_s
break if name.empty?
sequence.include_directories << name
end
end
private def read_filename_table(sequence)
loop do
name = @io.gets('\0', chomp: true).to_s
break if name.empty?
dir = DWARF.read_unsigned_leb128(@io)
time = DWARF.read_unsigned_leb128(@io)
length = DWARF.read_unsigned_leb128(@io)
sequence.file_names << {name, dir.to_i, time.to_i, length.to_i}
end
end
private macro increment_address_and_op_index(operation_advance)
if sequence.maximum_operations_per_instruction == 1
registers.address += {{operation_advance}} * sequence.minimum_instruction_length
else
registers.address += sequence.minimum_instruction_length *
((registers.op_index + operation_advance) // sequence.maximum_operations_per_instruction)
registers.op_index = (registers.op_index + operation_advance) % sequence.maximum_operations_per_instruction
end
end
# TODO: support LNE::DefineFile (manually register file, uncommon)
private def read_statement_program(sequence)
registers = Register.new(sequence.default_is_stmt)
loop do
opcode = @io.read_byte.not_nil!
if opcode >= sequence.opcode_base
# special opcode
adjusted_opcode = opcode - sequence.opcode_base
operation_advance = adjusted_opcode // sequence.line_range
increment_address_and_op_index(operation_advance)
registers.line &+= sequence.line_base + (adjusted_opcode % sequence.line_range)
register_to_matrix(sequence, registers)
registers.reset
elsif opcode == 0
# extended opcode
len = DWARF.read_unsigned_leb128(@io) - 1 # -1 accounts for the opcode
extended_opcode = LNE.new(@io.read_byte.not_nil!)
case extended_opcode
when LNE::EndSequence
registers.end_sequence = true
register_to_matrix(sequence, registers)
if (@io.tell - @offset - sequence.offset) < sequence.total_length
registers = Register.new(sequence.default_is_stmt)
else
break
end
when LNE::SetAddress
case len
when 8 then registers.address = @io.read_bytes(UInt64)
when 4 then registers.address = @io.read_bytes(UInt32).to_u64
else @io.skip(len)
end
registers.op_index = 0_u32
when LNE::SetDiscriminator
registers.discriminator = DWARF.read_unsigned_leb128(@io)
else
# skip unsupported opcode
@io.read_fully(Bytes.new(len))
end
else
# standard opcode
standard_opcode = LNS.new(opcode)
case standard_opcode
when LNS::Copy
register_to_matrix(sequence, registers)
registers.reset
when LNS::AdvancePc
operation_advance = DWARF.read_unsigned_leb128(@io)
increment_address_and_op_index(operation_advance)
when LNS::AdvanceLine
registers.line &+= DWARF.read_signed_leb128(@io)
when LNS::SetFile
registers.file = DWARF.read_unsigned_leb128(@io)
when LNS::SetColumn
registers.column = DWARF.read_unsigned_leb128(@io)
when LNS::NegateStmt
registers.is_stmt = !registers.is_stmt
when LNS::SetBasicBlock
registers.basic_block = true
when LNS::ConstAddPc
adjusted_opcode = 255 - sequence.opcode_base
operation_advance = adjusted_opcode // sequence.line_range
increment_address_and_op_index(operation_advance)
when LNS::FixedAdvancePc
registers.address += @io.read_bytes(UInt16).not_nil!
registers.op_index = 0_u32
when LNS::SetPrologueEnd
registers.prologue_end = true
when LNS::SetEpiloqueBegin
registers.epilogue_begin = true
when LNS::SetIsa
registers.isa = DWARF.read_unsigned_leb128(@io)
else
# consume unknown opcode args
n_args = sequence.standard_opcode_lengths[opcode.to_i]
n_args.times { DWARF.read_unsigned_leb128(@io) }
end
end
end
end
@current_sequence_matrix : Array(Row)?
private def register_to_matrix(sequence, registers)
# checking is_stmt should be enough to avoid "non statement" operations
# some of which have confusing line number 0.
# but some operations within macros seem to be useful and marked as !is_stmt
# so attempt to include them also
if registers.is_stmt || (registers.line.to_i > 0 && registers.column.to_i > 0)
file = sequence.file_names[registers.file]
path = sequence.include_directories[file[1]]
row = Row.new(
registers.address + @base_address,
registers.op_index,
path,
file[0],
registers.line.to_i,
registers.column.to_i,
registers.end_sequence
)
if rows = @current_sequence_matrix
rows << row
else
matrix << (rows = [row])
@current_sequence_matrix = rows
end
end
if registers.end_sequence
@current_sequence_matrix = nil
end
end
end
end
end