Lldb

mohitmishra786/low-level-dev-skills/skills/debuggers/lldb

作者 mohitmishra786bdc58472fa9f无许可证253 个星标收录于 2026年10月9日更新于 2026年10月9日仓库3个月前更新

LLDB debugger skill for C/C++/Swift/Objective-C programs. Use when debugging with LLDB on macOS, FreeBSD, or Linux-clang environments, mapping GDB mental models to LLDB commands, using LLDB in Xcode or VS Code, or debugging Swift/Objective-C. Activates on queries about LLDB commands, GDB to LLDB migration, Apple platform debugging, LLDB Python scripting, or IDE-integrated debugging with clang-built binaries.

仅含说明Software Development

AI 生成的概览

指导 LLDB 调试会话，并将 GDB 命令映射到 LLDB，适用于 C、C++、Swift 和 Objective-C 程序。

功能: 该技能提供运行 LLDB 调试会话的说明，包括启动 LLDB、设置断点和监视点、查看变量、内存和寄存器，以及管理线程。它包含 GDB 到 LLDB 的命令对照表、Apple/macOS 相关内容（如 Objective-C 对象打印和 image lookup）、VS Code CodeLLDB 启动配置，以及 LLDB Python 脚本示例。它还指向一个包含更完整 GDB-LLDB 命令对照的参考文件。
适用场景: 适用于使用 LLDB 调试 C、C++、Swift 或 Objective-C 程序，尤其是在 macOS、FreeBSD 或基于 clang 的 Linux 环境中。也适合将已有的 GDB 知识转换为 LLDB 命令、调试 Apple 平台代码，或在 Xcode 或 VS Code 中配置 LLDB。
运行要求: 不附带脚本，仅为说明文档。使用所述工作流需要 LLDB 调试器和带调试信息的已编译二进制文件；VS Code 部分假定已安装 CodeLLDB 扩展。

LLDB

Purpose

Guide agents through LLDB sessions and map existing GDB knowledge to LLDB. Covers command differences, Apple specifics, Python scripting, and IDE integration.

Triggers

"I'm on macOS and need to debug a C++ program"
"How does LLDB differ from GDB?"
"How do I do [GDB command] in LLDB?"
"LLDB shows <unavailable> for variables"
"How do I use LLDB in VS Code?"
"How do I write an LLDB Python script?"

Workflow

1. Start LLDB

bash

lldb ./prog                         # load binarylldb ./prog -- arg1 arg2            # with argumentslldb -p 12345                       # attach to PIDlldb -c core.1234                   # load core dumplldb ./prog core.1234               # binary + core

lldb ./prog                         # load binarylldb ./prog -- arg1 arg2            # with argumentslldb -p 12345                       # attach to PIDlldb -c core.1234                   # load core dumplldb ./prog core.1234               # binary + core

2. GDB → LLDB command map

Source: https://lldb.llvm.org/use/map.html

GDB	LLDB	Notes
`run [args]`	`process launch [args]` / `r`
`continue`	`process continue` / `c`
`next`	`thread step-over` / `n`
`step`	`thread step-in` / `s`
`nexti`	`thread step-inst-over` / `ni`
`stepi`	`thread step-inst` / `si`
`finish`	`thread step-out` / `finish`
`break main`	`breakpoint set -n main` / `b main`
`break file.c:42`	`breakpoint set -f file.c -l 42` / `b file.c:42`
`break *0x400abc`	`breakpoint set -a 0x400abc` / `b -a 0x400abc`
`watch x`	`watchpoint set variable x` / `wa s v x`
`print x`	`frame variable x` / `p x`
`print/x x`	`p/x x`
`info locals`	`frame variable` / `fr v`
`info args`	`frame variable --arguments`
`backtrace`	`thread backtrace` / `bt`
`frame N`	`frame select N` / `f N`
`info threads`	`thread list`
`thread N`	`thread select N`
`thread apply all bt`	`thread backtrace all`
`x/10wx addr`	`memory read -s4 -fx -c10 addr` / `x/10xw addr`
`set var = 42`	`expression var = 42` / `expr var = 42`
`quit`	`quit` / `q`

3. Breakpoints

lldb

# By nameb mainbreakpoint set --name foobreakpoint set --name foo --condition 'x > 0'
# By file:lineb file.c:42breakpoint set --file file.c --line 42
# By addressb -a 0x100003f20
# By regexbreakpoint set --func-regex '^MyClass::'
# Listbreakpoint list / br l
# Deletebreakpoint delete 2
# Disable/enablebreakpoint disable 1breakpoint enable 1
# Commands on hitbreakpoint command add 1  > p x  > continue  > DONE

# By nameb mainbreakpoint set --name foobreakpoint set --name foo --condition 'x > 0'
# By file:lineb file.c:42breakpoint set --file file.c --line 42
# By addressb -a 0x100003f20
# By regexbreakpoint set --func-regex '^MyClass::'
# Listbreakpoint list / br l
# Deletebreakpoint delete 2
# Disable/enablebreakpoint disable 1breakpoint enable 1
# Commands on hitbreakpoint command add 1  > p x  > continue  > DONE

4. Inspect state

lldb

# Print variablep xframe variable xp *ptrp arr[0]
# Print expressionexpression x * 2 + 1expr (int)sqrt(9.0)
# All localsframe variablefr v -a          # include arguments
# Registersregister readregister read rip rsp
# Memorymemory read --size 4 --format x --count 10 0x7fff0000x/10xw 0x7fff0000          # GDB-compatible syntax
# Type infoimage lookup --type MyClasstype lookup MyClass

# Print variablep xframe variable xp *ptrp arr[0]
# Print expressionexpression x * 2 + 1expr (int)sqrt(9.0)
# All localsframe variablefr v -a          # include arguments
# Registersregister readregister read rip rsp
# Memorymemory read --size 4 --format x --count 10 0x7fff0000x/10xw 0x7fff0000          # GDB-compatible syntax
# Type infoimage lookup --type MyClasstype lookup MyClass

5. Watchpoints

lldb

watchpoint set variable x           # write watchpointwatchpoint set variable -w read x   # read watchpointwatchpoint set variable -w read_write xwatchpoint set expression -- &x     # by address
watchpoint listwatchpoint delete 1

watchpoint set variable x           # write watchpointwatchpoint set variable -w read x   # read watchpointwatchpoint set variable -w read_write xwatchpoint set expression -- &x     # by address
watchpoint listwatchpoint delete 1

6. Threads

lldb

thread listthread select 3thread backtrace allthread backtrace --count 5           # limit depth
# Per-thread steppingthread step-over                     # step this thread only

thread listthread select 3thread backtrace allthread backtrace --count 5           # limit depth
# Per-thread steppingthread step-over                     # step this thread only

7. macOS / Apple specifics

lldb

# Symbol lookup in shared cacheimage lookup --address 0x18ab12345image lookup --name objc_msgSend
# Objective-C method breakpointb "-[NSArray objectAtIndex:]"b "+[NSString stringWithFormat:]"
# Inspect Objective-C objectpo myObject                          # print-object (calls -description)po [arr count]
# Show loaded librariesimage listimage list -b                        # brief (names only)

# Symbol lookup in shared cacheimage lookup --address 0x18ab12345image lookup --name objc_msgSend
# Objective-C method breakpointb "-[NSArray objectAtIndex:]"b "+[NSString stringWithFormat:]"
# Inspect Objective-C objectpo myObject                          # print-object (calls -description)po [arr count]
# Show loaded librariesimage listimage list -b                        # brief (names only)

8. VS Code integration

Install the CodeLLDB extension. .vscode/launch.json:

json

{  "version": "0.2.0",  "configurations": [    {      "name": "Debug (lldb)",      "type": "lldb",      "request": "launch",      "program": "${workspaceFolder}/build/prog",      "args": [],      "cwd": "${workspaceFolder}",      "preLaunchTask": "build"    }  ]}

{  "version": "0.2.0",  "configurations": [    {      "name": "Debug (lldb)",      "type": "lldb",      "request": "launch",      "program": "${workspaceFolder}/build/prog",      "args": [],      "cwd": "${workspaceFolder}",      "preLaunchTask": "build"    }  ]}

9. LLDB Python scripting

python

import lldb
def print_all_threads(debugger, command, result, internal_dict):    target = debugger.GetSelectedTarget()    process = target.GetProcess()    for thread in process:        print(f"Thread {thread.GetIndexID()}: {thread.GetName()}")        for frame in thread:            print(f"  {frame}")
def __lldb_init_module(debugger, internal_dict):    debugger.HandleCommand('command script add -f myscript.print_all_threads pthreads')

import lldb
def print_all_threads(debugger, command, result, internal_dict):    target = debugger.GetSelectedTarget()    process = target.GetProcess()    for thread in process:        print(f"Thread {thread.GetIndexID()}: {thread.GetName()}")        for frame in thread:            print(f"  {frame}")
def __lldb_init_module(debugger, internal_dict):    debugger.HandleCommand('command script add -f myscript.print_all_threads pthreads')

Load: command script import /path/to/myscript.py

For a full GDB↔LLDB command map, see references/gdb-lldb-map.md [blocked].

Related skills

Use skills/debuggers/gdb for GDB workflows
Use skills/debuggers/core-dumps for core dump analysis
Use skills/compilers/clang for building with debug info

来源与署名

来源：mohitmishra786/low-level-dev-skills位于skills/debuggers/lldb提交bdc5847

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Lldb

LLDB

Purpose

Triggers

Workflow

1. Start LLDB

2. GDB → LLDB command map

3. Breakpoints

4. Inspect state

5. Watchpoints

6. Threads

7. macOS / Apple specifics

8. VS Code integration

9. LLDB Python scripting

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