How to Play LLDB in iOS runtime?

Transcript

1. How to play with LLDB in iOS runtime? @stinge

2. • slide url
 https://ppt.cc/fhdtqx • QR Code

3. Background stinge • Mercari iOS Engineer • twitter: @StingeSu •

   hobby: traveling & cooking

4. Outline • Why LLDB(Low Level Debugger)? • How LLDB works?

   • LLDB OSS • Custom LLDB command

5. Why LLDB? • high-performance debugger • Clang expression parser &

   LLVM disassembler • Default debugger in Xcode • Run Swift REPL & python supported • Save your time

6. Clang v.s GCC(GNU Compiler Collection) Clang • Apple official compiler

   • Frontend for LLVM • High performance • BSD license • …… GCC • Linux based • Support more languages • GPL license

7. Clang (Xcode 10.2.1) GCC (Darwin Kernel on Raspberry Pi)

8. • How Apple deprecated GCC Front-end Back-end Xcode 3 GCC

   GCC Xcode 4 GCC LLVM Xcode 5 Clang LLVM

9. • gcc hello.c

10. Is it good for iOS?

11. Is it good for iOS? NO 

12. build process

13. Clang-Swift • The compiler process of swift cmd+B

14. Clang-Swift • The compiler process of swift Clang AST Reference

    https://ppt.cc/fnA4Qx

15. Clang-Swift • The compiler process of swift

16. How LLDB works?

17. How LLDB works? command action option argument

18. None

19. • p(print) → expr -- expr -- foo • po(print

    object) → expr -O -- expr -O -- foo

20. p v.s po

21. None

22. • Changes the value of variables • Creates temporary variables

    • Validates the values

23. • DEMO • Tasks 1. Changes UIButton title into red

    2. Moves UIView up

24. • Can we use a efficient way to finish these

    commands?
 - YES

25. LLDB Python API https://lldb.llvm.org/python_reference/index.html

26. LLDB OSS • Facebook/chisel • DEMO

27. Customized command • nudge(swift) • DEMO https://gist.github.com/sTinGe/059dc4c15347b7fef4ee537efdcc6e53