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LLDB 小结

简介

LLDB 是新一代高性能调试器，其是一组可重用组件的集合，这些组件大多是 LLVM 工程中的类库，如 Clang 表达式解析器或 LLVM 反汇编程序等。LLDB 是 Xcode 中默认的调试器，并且支持调试 C／C++ 程序，详情参考。

LLDB 命令

LLDB 的命令格式不同于 GDB 的命令格式的随意，而是统一为如下格式：

<命令名称> <命令动作> [-可选项 [可选项的值]] [参数1 [参数2···]]

需要注意的是，不管是命令名称、命令动作、可选项还是参数，它们都是由空格分隔的，所以如果，参数本身包含由空格符号，那么，使用双引号来包裹参数，如果，参数中包含有反斜杠或双引号，那么使用反斜杠对它们进行转义。

多个可选项在命令行中的顺序并不是固定的，但是如果可选项后的参数是以 - 开始的，那么需要使用 -- 标记可选项的结束，如下面的命令：

(lldb) process launch --stop-at-entry -- -program_arg_1 value -program_arg_2 value//可选项顺序可以不固定(lldb) breakpoint set -l 34 -f UIView+Theme.m(lldb) breakpoint set -f UIView+Theme.m -l 35

开启调试

打开命令行，使用如下命令：

Martin-mini:Applications hanxuejian$ lldb zoom.us.app/(lldb) target create "zoom.us.app/"Current executable set to 'zoom.us.app/' (i386).

或者

Martin-mini:Applications hanxuejian$ lldb(lldb) file zoom.us.app/Current executable set to 'zoom.us.app/' (i386).(lldb) quitMartin-mini:Applications hanxuejian$

或者使用 Xcode 进入调试模式。

结束调试

(lldb) quit

设置命令别名

对于常用的命令，可以设置别名，使其简单化，如：

(lldb) breakpoint set --file foo.c --line 12(lldb) command alias bfl breakpoint set -f %1 -l %2 (lldb) bfl foo.c 12

取消命令的别名

(lldb) command unalias b(lldb) command alias b breakpoint

设置断点

1. 指定文件及代码行

   (lldb) breakpoint set --file foo.c --line 12 (lldb) breakpoint set -f foo.c -l 12

2. 指定函数名称

   (lldb) breakpoint set --name foo (lldb) breakpoint set -n foo(lldb) breakpoint set --name foo --name bar

3. 指定方法名称

   (lldb) breakpoint set --method foo (lldb) breakpoint set -M foo

4. 指定 OC 选择器

   (lldb) breakpoint set --selector alignLeftEdges: (lldb) breakpoint set -S alignLeftEdges:

5. 指定映像文件

   (lldb) breakpoint set --shlib foo.dylib --name foo (lldb) breakpoint set -s foo.dylib -n foo//--shlib 可以重复使用(lldb) breakpoint set --shlib foo.dylib --name foo --shlib foo1.dylib --name foo1

编辑断点

1. 查看设置的断点

   (lldb) breakpoint list

   如下面的例子：

   (lldb) breakpoint set -M loadBreakpoint 12: 25 locations.(lldb) breakpoint listCurrent breakpoints:12: name = 'load', locations = 25, resolved = 25, hit count = 0  12.1: where = MobileCoreServices`_LSPreferences::load(), address = 0x00000001072bc684, resolved, hit count = 0   12.2: where = libicucore.A.dylib`icu::CollationRoot::load(UErrorCode&), address = 0x00000001074eef18, resolved, hit count = 0   12.3: where = libicucore.A.dylib`icu::VTimeZone::load(icu::VTZReader&, UErrorCode&), address = 0x00000001075c2b34, resolved, hit count = 0   12.4: where = WebCore`WebCore::CachedFont::load(WebCore::CachedResourceLoader&, WebCore::ResourceLoaderOptions const&), address = 0x000000010aa16a20, resolved, hit count = 0   12.5: where = WebCore`WebCore::CachedImage::load(WebCore::CachedResourceLoader&, WebCore::ResourceLoaderOptions const&), address = 0x000000010aa18170, resolved, hit count = 0   12.6: where = WebCore`WebCore::CachedResource::load(WebCore::CachedResourceLoader&, WebCore::ResourceLoaderOptions const&), address = 0x000000010aa1dc40, resolved, hit count = 0   12.7: where = WebCore`WebCore::CachedSVGDocumentReference::load(WebCore::CachedResourceLoader&, WebCore::ResourceLoaderOptions const&), address = 0x000000010aa2ad20, resolved, hit count = 0   12.8: where = WebCore`WebCore::CSSFontFace::load(), address = 0x000000010aafab20, resolved, hit count = 0   12.9: where = WebCore`WebCore::CSSFontFaceSource::load(WebCore::CSSFontSelector&), address = 0x000000010ab028a0, resolved, hit count = 0   12.10: where = WebCore`WebCore::FontFace::load(), address = 0x000000010ad5a2a0, resolved, hit count = 0   12.11: where = WebCore`WebCore::FontFaceSet::load(WTF::String const&, WTF::String const&, WebCore::DOMPromise
        
         
          
           , 0ul, WTF::CrashOnOverflow, 16ul> >&&), address = 0x000000010ad5ad60, resolved, hit count = 0   12.12: where = WebCore`WebCore::FrameLoader::load(WebCore::DocumentLoader*), address = 0x000000010ad9fc70, resolved, hit count = 0   12.13: where = WebCore`WebCore::HRTFDatabaseLoader::load(), address = 0x000000010ae22e20, resolved, hit count = 0   12.14: where = WebCore`WebCore::HTMLMediaElement::load(), address = 0x000000010ae7e7f0, resolved, hit count = 0   12.15: where = WebCore`WebCore::JSFontFace::load(JSC::ExecState&), address = 0x000000010b1017f0, resolved, hit count = 0   12.16: where = WebCore`WebCore::MediaPlayer::load(WebCore::URL const&, WebCore::ContentType const&, WTF::String const&), address = 0x000000010b3d3ad0, resolved, hit count = 0   12.17: where = WebCore`WebCore::NullMediaPlayerPrivate::load(WTF::String const&), address = 0x000000010b3d6820, resolved, hit count = 0   12.18: where = WebCore`WebCore::MediaPlayerPrivateAVFoundation::load(WTF::String const&), address = 0x000000010b3d7880, resolved, hit count = 0   12.19: where = WebCore`WebCore::TextTrackLoader::load(WebCore::URL const&, WTF::String const&, bool), address = 0x000000010b8d89d0, resolved, hit count = 0   12.20: where = WebCore`WebCore::FrameLoader::load(WebCore::FrameLoadRequest const&), address = 0x000000010ada2570, resolved, hit count = 0   12.21: where = NLP`NL::SpotlightQueryConverter::load(NLSearchAppContext), address = 0x000000010fc3a4ca, resolved, hit count = 0   12.22: where = NLP`NL::SearchDateDisplayFormatter::load(), address = 0x000000010fc7c354, resolved, hit count = 0   12.23: where = libmarisa.dylib`marisa::Trie::load(char const*), address = 0x000000010fda4618, resolved, hit count = 0   12.24: where = JavaScriptCore`JSC::DFG::ByteCodeParser::load(unsigned int, unsigned int, JSC::DFG::GetByOffsetMethod const&, JSC::DFG::NodeType), address = 0x0000000110184900, resolved, hit count = 0   12.25: where = JavaScriptCore`JSC::DFG::ByteCodeParser::load(unsigned int, JSC::ObjectPropertyConditionSet const&, JSC::DFG::NodeType), address = 0x0000000110184ad0, resolved, hit count = 0 (lldb)
          
         
        

   在使用命令设置断点时，符合条件的断点可能不止一个，并且，如果新加载文件后，符合条件的断点可能还会增加。当然，设置不存在的断点，断点信息也可以查看得到，但是其 locations 为 0 。

   (lldb) breakpoint set --file test.m --line 100Breakpoint 13: no locations (pending).WARNING:  Unable to resolve breakpoint to any actual locations.(lldb) breakpoint listCurrent breakpoints:13: file = 'test.m', line = 100, exact_match = 0, locations = 0 (pending)

2. 将断点置为不可用

   (lldb) breakpoint disable 11 breakpoints disabled.

3. 将断点置为可用

   (lldb) breakpoint enable 11 breakpoints enabled.

4. 删除断点

   (lldb) breakpoint delete 11 breakpoints deleted; 0 breakpoint locations disabled.

5. 为断点添加命令或脚本

   (lldb) breakpoint command addEnter your debugger command(s).  Type 'DONE' to end.> bt> DONE(lldb) breakpoint command list 2Breakpoint 2:    Breakpoint commands:      bt(lldb)

   从下面的错误命令可知断点所支持的语言：

   (lldb) breakpoint command add -s OCerror: invalid enumeration value, valid values are: "command", "python", "default-script"

观察变量

1. 设置观察变量

   (lldb) watchpoint set variable backgroundColorWatchpoint created: Watchpoint 2: addr = 0x7fff52dcdb38 size = 8 state = enabled type = w    declare @ '/Users/hanxuejian/Downloads/ThemeChange-master/TestTheme/TestTheme/UIView+Theme.m:31'    watchpoint spec = 'backgroundColor'    new value: 0x000061000007e780

2. 查看观察变量

   (lldb) watchpoint listNumber of supported hardware watchpoints: 4Current watchpoints:Watchpoint 1: addr = 0x7fff52dcd6d8 size = 8 state = disabled type = w    declare @ '/Users/hanxuejian/Downloads/ThemeChange-master/TestTheme/TestTheme/UIView+Theme.m:31'    watchpoint spec = 'backgroundColor'    old value: 0xffff8067ddcff720    new value: 0xffff8067ddcff720Watchpoint 2: addr = 0x7fff52dcdb38 size = 8 state = enabled type = w    declare @ '/Users/hanxuejian/Downloads/ThemeChange-master/TestTheme/TestTheme/UIView+Theme.m:31'    watchpoint spec = 'backgroundColor'    new value: 0x000061000007e780

3. 设置查看条件

   (lldb) watchpoint set variable numWatchpoint created: Watchpoint 1: addr = 0x10f932558 size = 4 state = enabled type = w    declare @ '/Users/hanxuejian/Downloads/ThemeChange-master/TestTheme/TestTheme/UIView+Theme.m:31'    watchpoint spec = 'num'    new value: 16//添加条件(lldb) watchpoint modify -c "(num == 25)"(lldb) watchpoint listNumber of supported hardware watchpoints: 4Current watchpoints:Watchpoint 1: addr = 0x10f932558 size = 4 state = enabled type = w    declare @ '/Users/hanxuejian/Downloads/ThemeChange-master/TestTheme/TestTheme/UIView+Theme.m:31'    watchpoint spec = 'num'    old value: 20    new value: 21    condition = '(num == 25)'//条件达成2018-03-21 19:11:44.302 TestTheme[6938:828079] XPC connection interruptedWatchpoint 1 hit:old value: 21new value: 25

开始程序

使用 LLDB 调试程序，可以直接加载可执行程序，或者绑定已经在执行的程序，而后开始进行调试。

如下面的例子，先创建一个简单 C 程序。

#include 
   
    int main(int argc, char const *argv[]){     int i = 1;    while(true) {        char *c = "this is a test";        printf("%s %i\n", c,i++);       }    return 0;}
   

编辑后，保存为 test.cpp 文件，然后在命令行中执行下面的命令：

gcc test.cpp -o test

得到可执行文件，而后执行下面的命令。

(lldb) target create testCurrent executable set to 'test' (x86_64).(lldb) process launch testProcess 7169 launched: '/Users/hanxuejian/Desktop/Temp/test' (x86_64)this is a test 1this is a test 2this is a test 3this is a test 4

当然，也可以先运行 test 可执行文件，而后使用下面的命令进行调试绑定。

(lldb) process attach --pid 7232 (lldb) process attach --name test (lldb) process attach --name test --waitfor

但是要注意的是，如果存在两个名称相同的进程，那么绑定是无法成功的。

线程控制

在加载进程开始调试后，当执行到设置断点时，可以使用 thread 命令控制代码的执行。

1. 线程继续执行

   (lldb) thread continue Resuming thread 0x2c03 in process 46915 Resuming process 46915 (lldb)

2. 线程进入、单步执行或跳出

   (lldb) thread step-in    (lldb) thread step-over  (lldb) thread step-out

3. 单步指令的执行

   (lldb) thread step-inst  (lldb) thread step-over-ins

4. 执行指定代码行数直到退出当前帧

   (lldb) thread until 100

5. 查看线程列表，第一个线程为当前执行线程

   (lldb) thread listProcess 46915 state is Stopped* thread #1: tid = 0x2c03, 0x00007fff85cac76a, where = libSystem.B.dylib`__getdirentries64 + 10, stop reason = signal = SIGSTOP, queue = com.apple.main-thread  thread #2: tid = 0x2e03, 0x0000

6. 查看当前线程栈

   (lldb) thread backtracethread #1: tid = 0x2c03, stop reason = breakpoint 1.1, queue = com.apple.main-thread frame #0: 0x0000000100010d5b, where = Sketch`-[SKTGraphicView alignLeftEdges:] + 33 at /Projects/Sketch/SKTGraphicView.m:1405 frame #1: 0x00007fff8602d152, where = AppKit`-[NSApplication sendAction:to:from:] + 95 frame #2: 0//查看所有线程的调用栈(lldb) thread backtrace all

7. 设置当前线程

   (lldb) thread select 2

帧状态

查看当前线程中当前帧（或者说方法/函数）中的变量/参数，可以使用 frame 命令。

1. 查看本地变量及参数

   (lldb) frame variable (ViewController *) self = 0x00007f8289d08b50(SEL) _cmd = "testCoreGraphics"(TestView *) view = 0x00007f828c102760//指定要查看的变量((lldb) frame variable self->isa(Class) self->isa = ViewController

2. 打印对象

   (lldb) frame variable -o self(ViewController *) self = 0x00007f8289d08b50 
        

3. 选择栈中的方法

   (lldb) frame select 2frame #2: 0x000000010ca7446c UIKit`-[UIViewController loadViewIfRequired] + 1235UIKit`-[UIViewController loadViewIfRequired]:    0x10ca7446c <+1235>: movl   (%r14), %eax    0x10ca7446f <+1238>: testl  %eax, %eax    0x10ca74471 <+1240>: je     0x10ca7447f               ; <+1254>    0x10ca74473 <+1242>: cmpl   $0x70000, %eax            ; imm = 0x70000 (lldb)

修改变量或调用函数

使用 expression 命令可以在调试过程中修改变量的值，或者执行函数。

1. 修改变量值

   (lldb) expression a(int) $0 = 9(lldb) frame variable a(int) a = 9(lldb) expression a=10(int) $1 = 10(lldb) frame variable a(int) a = 10(lldb)

2. 调用函数

   (lldb) expression printf("execute function %i",a)(int) $2 = 19execute function 10

   对于执行结果都会自动保存，以备他用。

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