Fancy debug tips with LLDB

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DEBUG 蕕䌷瞲ܖ ᮎ犚፡蚏㬵ṛ羷ጱLLDBಋ玊 Pofat

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LLDB膏౯ҁጱ獮獋ଙ҂

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Compiling was like…

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矦کSwift 盅…

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Print Commands • p , print, call : expression —    • po: expression -O —     

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Not Only ‘Print Commands’

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婘䌃کࠔӞ蟴䌘ܨݢ • 犥ӥ獋ᘏ缛㰷       

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ݢਯޞ虋碍 $樄毣ԏ虋碍ݢਂࣁෝ lldb ጱ绚樌

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ݢਯޞ虋碍

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襑ᥝ瞲ਧࣳ獨

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襑ᥝ瞲ਧࣳ獨 ObjC Swift

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窕纷矒ګ

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窕纷矒ګ

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thread backtrace

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瑽ᛔ http://condor.depaul.edu/slytinen/406s16/ch3.html

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瑽ᛔ http://condor.depaul.edu/slytinen/406s16/ch3.html

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Frame

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Breakpoints • -n : func or symbol name        • li : list all breakpoints     

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help & apropos

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Who did this?

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Print? Think again!

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Print? Think again! 暱࿆硲Ԫ֦碁מ牫  กॠᥝӤ娄牧merge盅ጱcode 犋Ꭳ螇ெ讕ԧ  薟䌃ԧ礓㮆 customs view ጱ _layer

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Print? Think again! Watchpoint

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Better way to log

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Better way to log maybe • Breakpoints will minimize the aﬀect to ﬂow • Need a way to import/export breakpoints     

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UI 砺֢ - present VC

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UI 砺֢ - view hierarchy

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Viva la Python

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.lldbinit ~/command.py ~/.lldbinit

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Chisel

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Chisel • border                   

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Chisel • visualize                   

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Chisel • bmessage                   

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Chisel in Swift context • error: error: use of undeclared identiﬁer ‘CGFloat' • CGFloat is deﬁned by macro in objc. In Swift, it’s not. 

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Target ~/.lldbinit

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瑽 by David Lin

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Image lookup

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Image lookup • ݢತᐺ磪 API • 犖ݢࣁ lldb 愊狶 method swizzling       

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Image lookup • ݢತᐺ磪 API • 犖ݢࣁ lldb 愊狶 method swizzling       

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Registers • $rip : Current instruct pointer • $rdi: First argument • $rsi, $rdx, $rcx, $R8, $R9: Second, third, forth, ﬁfth and sixth arguments • Others will be on stack

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Registers • $rip : Current instruct pointer • $rdi: First argument • $rsi, $rdx, $rcx, $R8, $R9: Second, third, forth, ﬁfth and sixth arguments • Others will be on stack

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Registers • $rsp : head of current frame ( head is smaller than bottom) • $rbp: bottom of current frame • $rax: Return register

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Registers 瑽ᛔ http://condor.depaul.edu/slytinen/406s16/ch3.html

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瑽ᛔ http://condor.depaul.edu/slytinen/406s16/ch3.html

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Witness “Witness Table”

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Witness “Witness Table” legs: 8 heads: 2 Metadata Witness Table

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Witness “Witness Table” legs: 8 heads: 2 Metadata Witness Table walk()

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Output all current state

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薹硯֦ጱᨗᚣ毣

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獊ᶎcommand line ࠩ

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Which one is better?

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Reference • Dancing in the Debugger - A waltz with LLDB • ဤ䋊ҁ盄羊䋿ጱӾ㾴硽䋊翕ᒊ҂ • WWDC 2014 Session 410 : Advanced Debugging in LLDB

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眤蘛ݱ֖