The document discusses debugging and evaluating expressions in LLDB. It provides examples of common LLDB commands for threads, stack backtraces, stepping, and evaluating expressions. It also discusses how commands like "po", "p", and "v" work under the hood to evaluate expressions by compiling and executing code. Additional tips are provided for using Chisel to add advanced debugging capabilities to LLDB. Links to external resources on advanced LLDB debugging techniques are also included.

3. • 現 iOS (16.10 ~ )
• : minsone.github.io

4. • LLDB
• LLDB
• Execution Commands
• Evaluating Expression
• Script - Python REPL
• Chisel
• QA

5. LLDB

6. • Apple Xcode LLVM
• LLVM - LLDB
• https://lldb.llvm.org/
LLDB

7. LLDB
(Execution Commands)

8. Execution Commands

9. Execution Commands

10. # Thread
(lldb) thread list

11. # Thread 2
(lldb) thread select 2
(lldb) t 2

12. # stack backtrace
(lldb) thread backtrace
(lldb) bt

13. # stack backtrace
(lldb) thread backtrace all
(lldb) bt all

14. # stack backtrace frame
(lldb) thread backtrace -c 5 # 0~4 frame
(lldb) bt 5 # 0~4 frame
(lldb) thread backtrace -s 5 -c 10 # 5~14 frame

15. frame

16. # frame index
(lldb) frame select 3 # 3 Frame
(lldb) frame info
(lldb) fr s 0 # 0 Frame
(lldb) fr info

17. # frame
(lldb) up # frame select -relative=1
(lldb) up 3 #fr s -r3
(lldb) down # frame select -relative=-1
(lldb) down 4 # fr s -r-4

18. # frame
(lldb) frame variable [ ] # fr v [ ]
(lldb) frame variable --format x [ ] # fr v -f x [ ]
(lldb) frame variable -o [ ] # fr v -o [ ]

19. # global
(lldb) target variable
(lldb) target variable [ ]

20. #
(lldb) thread step-over
(lldb) next
(lldb) n

21. # frame
(lldb) thread step-in
(lldb) step
(lldb) s

22. # frame
(lldb) thread step-out
(lldb) finish

23. # /
(lldb) thread until 23
(lldb) thread until --frame 2 10

24. # / (1) - Command
(lldb) thread until 21
(lldb) thread jump --line 19
(lldb) thread jump --by -2

25. # (2) - Drag

26. LLDB
(Evaluating Expression)

27. • LLDB .
• .
• Pause Swift .
• p, po, fr v .
Evaluating Expression

28. • Expression
•
• LLDB .
Evaluating Expression

29. #

30. # Expression
# Print
# Print Object

31. Evaluating Expression
Command Alias for Execute
po [expession] expression -Object-description --
Code ,
debugDescription
description
LLDB formatter
p [expression] expression --
Code
LLDB formatter
v / fr v [name] frame variable
Code , LLDB
formatter

32. Evaluating Expression
Command Alias for Execute
po [expession] expression -Object-description --
Code ,
debugDescription
description
LLDB formatter
p [expression] expression --
Code
LLDB formatter
v / fr v [name] frame variable
Code , LLDB
formatter

33. “po” Under the Hood
(lldb) po view
: WWDC19 - LLDB: Beyond “po"

34. “po” Under the Hood
(lldb) po view
Create
compilable code
: WWDC19 - LLDB: Beyond “po"

35. func __lldb_expr() {
__lldb_res = view
}
“po” Under the Hood
(lldb) po view
Create
compilable code
: WWDC19 - LLDB: Beyond “po"

36. “po” Under the Hood
(lldb) po view
Create
compilable code
Compile
: WWDC19 - LLDB: Beyond “po"

37. “po” Under the Hood
(lldb) po view
Create
compilable code
Compile Execute
Get result
: WWDC19 - LLDB: Beyond “po"

38. func __lldb_expr2 -> String() {
return __lldb_res.description
}
“po” Under the Hood
(lldb) po view
Create
compilable code
Compile Execute
Create code to
access
description
Get result
: WWDC19 - LLDB: Beyond “po"

39. “po” Under the Hood
(lldb) po view
Create
compilable code
Compile Execute
Create code to
access
description
CompileGet result
: WWDC19 - LLDB: Beyond “po"

40. “po” Under the Hood
(lldb) po view
Create
compilable code
Compile Execute
Create code to
access
description
Compile ExecuteGet result
: WWDC19 - LLDB: Beyond “po"

41. “po” Under the Hood
(lldb) po view
Create
compilable code
Compile Execute
Create code to
access
description
Compile ExecuteGet result
“<UIView: 0x12345678>”
: WWDC19 - LLDB: Beyond “po"

42. “po” Under the Hood
(lldb) po view
Get string result
Create
compilable code
Compile Execute
Create code to
access
description
Compile ExecuteGet result
Display result
string
: WWDC19 - LLDB: Beyond “po"

43. Evaluating Expression
Command Alias for Execute
po [expession] expression -Object-description --
Code ,
debugDescription
description
LLDB formatter
p [expression] expression --
Code
LLDB formatter
v / fr v [name] frame variable
Code , LLDB
formatter

44. “p” Under the Hood
(lldb) p cruise
: WWDC19 - LLDB: Beyond “po"

45. “p” Under the Hood
Create
compilable code
Compile Execute
Get result
(lldb) p cruise
: WWDC19 - LLDB: Beyond “po"

46. “p” Under the Hood
Dynamic type
resolution
Create
compilable code
Compile Execute
Get result
(lldb) p cruise
: WWDC19 - LLDB: Beyond “po"

47. “p” Under the Hood
(lldb) p cruise
Create
compilable code
Compile Execute
Get result Formatter
Dynamic type
resolution
: WWDC19 - LLDB: Beyond “po"

48. Evaluating Expression
Command Alias for Execute
po [expession] expression -Object-description --
Code ,
debugDescription
description
LLDB formatter
p [expression] expression --
Code
LLDB formatter
v / fr v [name] frame variable
Code , LLDB
formatter

49. “v” Under the Hood
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

50. “v” Under the Hood
(lldb) v variable
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

51. “v” Under the Hood
Examine
program state
(lldb) v variable
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

52. “v” Under the Hood
Examine
program state
Read value from
memory
(lldb) v variable
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

53. “v” Under the Hood
Examine
program state
Read value from
memory
Dynamic type
resolution
(lldb) v variable
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

54. “v” Under the Hood
Examine
program state
Read value from
memory
Dynamic type
resolution
(lldb) v variable.field1
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

55. “v” Under the Hood
Examine
program state
Read value from
memory
Dynamic type
resolution
(lldb) v variable.field1 .field2
(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

56. “v” Under the Hood
Examine
program state
Read value from
memory
Dynamic type
resolution
(lldb) v variable.field1 .field2
Formatter(lldb) v variable
: WWDC19 - LLDB: Beyond “po"

57. •
• .
• .
Evaluating Expression

58. # Evaluating Expression -

59. # Evaluating Expression - Push

60. #

61. LLDB
(Script - Python REPL)

62. • Python LLDB Script .
Script - Python REPL
# Execute Script
# Import
# Default import

63. Chisel

64. • Facebook (https://github.com/facebook/
chisel)
• .
• iOS LLDB
Chisel

66. Advanced Apple Debugging
and Reverse Engineering
from. Raywenderlich

67. LLDB: Beyond "po" - https://developer.apple.com/videos/play/wwdc2019/429/
[Apple - LLDB Quick Start Guide](https://developer.apple.com/library/archive/documentation/IDEs/Conceptual/
gdb_to_lldb_transition_guide/document/Introduction.html#//apple_ref/doc/uid/TP40012917-CH1-SW1)
[UIKonf18 – Day 1 – Carola Nitz – Advanced Debugging Techniques](https://www.youtube.com/watch?v=578YdS2sNqk)
[Advanced Debugging with Xcode and LLDB](https://developer.apple.com/videos/play/wwdc2018/412)
[Chisel](https://github.com/facebook/chisel)
[LLDB Chisel Commands](https://kapeli.com/cheat_sheets/LLDB_Chisel_Commands.docset/Contents/Resources/Documents/
index)
[More than `po`: Debugging in lldb](https://www.slideshare.net/micheletitolo/more-than-po-debugging-in-lldb)
[Debugging RubyMotion applications](http://ruby-korea.github.io/RubyMotionDocumentation/articles/debugging/)
[Xcode LLDB ](https://www.letmecompile.com/xcode-lldb-%EB%94%94%EB%B2%84%EA%B9%85-
%ED%85%8C%ED%81%AC%EB%8B%89/)
[LLDB Debugging Cheat Sheet](https://gist.github.com/alanzeino/82713016fd6229ea43a8)
[Debugging a Debugger](http://idrisr.com/2015/10/12/debugging-a-debugger.html)
https://kapeli.com/cheat_sheets/LLDB_Chisel_Commands.docset/Contents/Resources/Documents/index
http://ios.137422.xyz/83589/
https://jayeshkawli.ghost.io/advanced-debugging-in-ios/
https://www.slideshare.net/YiyingTseng/debug-lldb-86558535
https://medium.com/flawless-app-stories/debugging-swift-code-with-lldb-b30c5cf2fd49
https://dailyhotel.io/advanced-debugging-with-xcode-and-lldb-8e8dc5326167
https://pspdfkit.com/blog/2018/how-to-extend-lldb-to-provide-a-better-debugging-experience/

68. QnA