配合LLDB調試器進行iOS代碼調試（二）

3.thread線程操作相關指令

     上面提到過，程式運作中會有多個激活的線程，每個線程中又有許多堆棧塊，frame相關指令用于綜合調試各個堆棧塊，thread指令則是用于綜合調試各個線程。首先Xcode左側導航區為我們列出的線程堆棧塊并不是目前線程中的所有堆棧塊，使用如下指令可以列印出目前線程的所有堆棧塊：

(lldb) thread backtrace

* thread #1: tid = 0x152f8, 0x0000000102497905 BreakPointTest`-[ViewController test](self=0x00007fcd5b413320, _cmd="test") + 37 at ViewController.m:39, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1

 * frame #0: 0x0000000102497905 BreakPointTest`-[ViewController test](self=0x00007fcd5b413320, _cmd="test") + 37 at ViewController.m:39

   frame #1: 0x00000001024978cb BreakPointTest`-[ViewController viewDidLoad](self=0x00007fcd5b413320, _cmd="viewDidLoad") + 91 at ViewController.m:31

   frame #2: 0x0000000103475984 UIKit`-[UIViewController loadViewIfRequired] + 1198

   frame #3: 0x0000000103475cd3 UIKit`-[UIViewController view] + 27

   frame #4: 0x000000010334bfb4 UIKit`-[UIWindow addRootViewControllerViewIfPossible] + 61

   frame #5: 0x000000010334c69d UIKit`-[UIWindow _setHidden:forced:] + 282

   frame #6: 0x000000010335e180 UIKit`-[UIWindow makeKeyAndVisible] + 42

   frame #7: 0x00000001032d2ed9 UIKit`-[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4131

   frame #8: 0x00000001032d9568 UIKit`-[UIApplication _runWithMainScene:transitionContext:completion:] + 1769

   frame #9: 0x00000001032d6714 UIKit`-[UIApplication workspaceDidEndTransaction:] + 188

   frame #10: 0x0000000105d438c8 FrontBoardServices`__FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 24

   frame #11: 0x0000000105d43741 FrontBoardServices`-[FBSSerialQueue _performNext] + 178

   frame #12: 0x0000000105d43aca FrontBoardServices`-[FBSSerialQueue _performNextFromRunLoopSource] + 45

   frame #13: 0x0000000102e4a301 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17

   frame #14: 0x0000000102e4022c CoreFoundation`__CFRunLoopDoSources0 + 556

   frame #15: 0x0000000102e3f6e3 CoreFoundation`__CFRunLoopRun + 867

   frame #16: 0x0000000102e3f0f8 CoreFoundation`CFRunLoopRunSpecific + 488

   frame #17: 0x00000001032d5f21 UIKit`-[UIApplication _run] + 402

   frame #18: 0x00000001032daf09 UIKit`UIApplicationMain + 171

   frame #19: 0x0000000102497c3f BreakPointTest`main(argc=1, argv=0x00007fff5d768668) + 111 at main.m:14

   frame #20: 0x00000001056fe92d libdyld.dylib`start + 1

   frame #21: 0x00000001056fe92d libdyld.dylib`start + 1

thread list指令則可以列印出目前所有激活的線程，如下：

(lldb) thread list

Process 1049 stopped

 thread #2: tid = 0x1531b, 0x0000000105a43ee2 libsystem_kernel.dylib`kevent64 + 10, queue = 'com.apple.libdispatch-manager'

 thread #3: tid = 0x1531c, 0x0000000105a435e2 libsystem_kernel.dylib`__workq_kernreturn + 10

 thread #4: tid = 0x15324, 0x0000000105a435e2 libsystem_kernel.dylib`__workq_kernreturn + 10

 thread #5: tid = 0x15328, 0x0000000105a435e2 libsystem_kernel.dylib`__workq_kernreturn + 10

thread info可以列印出目前選中調試的線程的資訊：

(lldb) thread info

thread #1: tid = 0x152f8, 0x0000000102497905 BreakPointTest`-[ViewController test](self=0x00007fcd5b413320, _cmd="test") + 37 at ViewController.m:39, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1

同樣也可以使用thread select指令來切換選中調試的線程：

(lldb) thread select 2

thread continue指令用于繼續執行目前的線程：

(lldb) thread continue

2016-04-24 12:29:54.562 BreakPointTest[1049:86776] 1

Resuming thread 0x152f8 in process 1049

Process 1049 resuming

4.disassemble代碼反彙編相關指令

     disassemble相關指令用于輸出某段程式的彙編代碼，執行disassemble指令将會反彙編目前函數：

BreakPointTest`-[ViewController test]:

   0x10aab7940 <+0>:  pushq  %rbp

   0x10aab7941 <+1>:  movq   %rsp, %rbp

   0x10aab7944 <+4>:  subq   $0x20, %rsp

   0x10aab7948 <+8>:  leaq   0x1711(%rip), %rax        ; @"%d"

   0x10aab794f <+15>: movq   %rdi, -0x8(%rbp)

   0x10aab7953 <+19>: movq   %rsi, -0x10(%rbp)

   0x10aab7957 <+23>: movl   $0x0, -0x14(%rbp)

   0x10aab795e <+30>: movl   $0x1, -0x18(%rbp)

->  0x10aab7965 <+37>: movl   -0x14(%rbp), %ecx

   0x10aab7968 <+40>: addl   -0x18(%rbp), %ecx

   0x10aab796b <+43>: movl   %ecx, -0x1c(%rbp)

   0x10aab796e <+46>: movl   -0x1c(%rbp), %esi

   0x10aab7971 <+49>: movq   %rax, %rdi

   0x10aab7974 <+52>: movb   $0x0, %al

   0x10aab7976 <+54>: callq  0x10aab7c80               ; symbol stub for: NSLog

   0x10aab797b <+59>: addq   $0x20, %rsp

   0x10aab797f <+63>: popq   %rbp

   0x10aab7980 <+64>: retq

    使用disassemble -b則會輸出帶位元組資訊的彙編代碼：

(lldb) disassemble -b

   0x10aab7940 <+0>:  55                    pushq  %rbp

   0x10aab7941 <+1>:  48 89 e5              movq   %rsp, %rbp

   0x10aab7944 <+4>:  48 83 ec 20           subq   $0x20, %rsp

   0x10aab7948 <+8>:  48 8d 05 11 17 00 00  leaq   0x1711(%rip), %rax        ; @"%d"

   0x10aab794f <+15>: 48 89 7d f8           movq   %rdi, -0x8(%rbp)

   0x10aab7953 <+19>: 48 89 75 f0           movq   %rsi, -0x10(%rbp)

   0x10aab7957 <+23>: c7 45 ec 00 00 00 00  movl   $0x0, -0x14(%rbp)

   0x10aab795e <+30>: c7 45 e8 01 00 00 00  movl   $0x1, -0x18(%rbp)

->  0x10aab7965 <+37>: 8b 4d ec              movl   -0x14(%rbp), %ecx

   0x10aab7968 <+40>: 03 4d e8              addl   -0x18(%rbp), %ecx

   0x10aab796b <+43>: 89 4d e4              movl   %ecx, -0x1c(%rbp)

   0x10aab796e <+46>: 8b 75 e4              movl   -0x1c(%rbp), %esi

   0x10aab7971 <+49>: 48 89 c7              movq   %rax, %rdi

   0x10aab7974 <+52>: b0 00                 movb   $0x0, %al

   0x10aab7976 <+54>: e8 05 03 00 00        callq  0x10aab7c80               ; symbol stub for: NSLog

   0x10aab797b <+59>: 48 83 c4 20           addq   $0x20, %rsp

   0x10aab797f <+63>: 5d                    popq   %rbp

   0x10aab7980 <+64>: c3                    retq

     使用disassemble -c 指令可以設定輸出彙編代碼的行數，如下：

(lldb) disassemble -c 5

     使用disassemble -l隻輸出目前斷點處彙編代碼：

BreakPointTest`-[ViewController test] + 37 at ViewController.m:30

  29       int b = 1;

-> 30       int c = a+b;

  31       NSLog(@"%d",c);

     使用disassemble -m混合顯示彙編代碼：

(lldb) disassemble -m

BreakPointTest`-[ViewController test] at ViewController.m:27

  26   }

  27   -(void)test{

  28       int a = 0;

BreakPointTest`-[ViewController test] + 23 at ViewController.m:28

BreakPointTest`-[ViewController test] + 30 at ViewController.m:29

  30       int c = a+b;

BreakPointTest`-[ViewController test] + 40 at ViewController.m:30

BreakPointTest`-[ViewController test] + 43 at ViewController.m:30

BreakPointTest`-[ViewController test] + 46 at ViewController.m:31

  32   }

BreakPointTest`-[ViewController test] + 49 at ViewController.m:31

BreakPointTest`-[ViewController test] + 59 at ViewController.m:32

  33   @end

     使用disassemble -p進行目前行的彙編代碼輸出：

(lldb) disassemble -p

5.其他LLDB常用指令

       bt指令用于列印目前線程所有堆棧塊資訊：

(lldb) bt

* thread #1: tid = 0x19f11, 0x000000010aab7965 BreakPointTest`-[ViewController test](self=0x00007fee9c11e330, _cmd="test") + 37 at ViewController.m:30, queue = 'com.apple.main-thread', stop reason = breakpoint 2.1

 * frame #0: 0x000000010aab7965 BreakPointTest`-[ViewController test](self=0x00007fee9c11e330, _cmd="test") + 37 at ViewController.m:30

   frame #1: 0x000000010aab792b BreakPointTest`-[ViewController viewDidLoad](self=0x00007fee9c11e330, _cmd="viewDidLoad") + 91 at ViewController.m:22

   frame #2: 0x000000010ba95984 UIKit`-[UIViewController loadViewIfRequired] + 1198

   frame #3: 0x000000010ba95cd3 UIKit`-[UIViewController view] + 27

   frame #4: 0x000000010b96bfb4 UIKit`-[UIWindow addRootViewControllerViewIfPossible] + 61

   frame #5: 0x000000010b96c69d UIKit`-[UIWindow _setHidden:forced:] + 282

   frame #6: 0x000000010b97e180 UIKit`-[UIWindow makeKeyAndVisible] + 42

   frame #7: 0x000000010b8f2ed9 UIKit`-[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4131

   frame #8: 0x000000010b8f9568 UIKit`-[UIApplication _runWithMainScene:transitionContext:completion:] + 1769

   frame #9: 0x000000010b8f6714 UIKit`-[UIApplication workspaceDidEndTransaction:] + 188

   frame #10: 0x000000010e3638c8 FrontBoardServices`__FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 24

   frame #11: 0x000000010e363741 FrontBoardServices`-[FBSSerialQueue _performNext] + 178

   frame #12: 0x000000010e363aca FrontBoardServices`-[FBSSerialQueue _performNextFromRunLoopSource] + 45

   frame #13: 0x000000010b46a301 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17

   frame #14: 0x000000010b46022c CoreFoundation`__CFRunLoopDoSources0 + 556

   frame #15: 0x000000010b45f6e3 CoreFoundation`__CFRunLoopRun + 867

   frame #16: 0x000000010b45f0f8 CoreFoundation`CFRunLoopRunSpecific + 488

   frame #17: 0x000000010b8f5f21 UIKit`-[UIApplication _run] + 402

   frame #18: 0x000000010b8faf09 UIKit`UIApplicationMain + 171

   frame #19: 0x000000010aab7c5f BreakPointTest`main(argc=1, argv=0x00007fff55148668) + 111 at main.m:14

   frame #20: 0x000000010dd1e92d libdyld.dylib`start + 1

   frame #21: 0x000000010dd1e92d libdyld.dylib`start + 1